wrote:\\n\\n> I don't think we're that far from having all of these though. To start\\n> with, we remove from CREATEROLE the random things that it does which go\\n> beyond what folks tend to expect- remove the whole 'grant any role to\\n> any other' stuff, remove the 'drop role' exception, remove the\\n> 'alter role' stuff. Do make it so that when you create a role, however,\\n> the above GRANT is effectively done. Now, for the items above where we\\n> removed the checks against have_createrole_privilege() we go back and\\n> add in checks using is_admin_of_role(). Of course, also remove the role\\n> self-administration bug.\\n>\\n> That's step #1, but it gets us more-or-less what you're looking for, I\\n> think, and brings us a lot closer to what the spec has.\\n>\\n\\nThat still leaves attribute specification in place: e.g., REPLICATION,\\nCREATEROLE, CREATEDB, etc... (I see BYPASSRLS already is SUPERUSER only)\\n\\nI dislike changing the documented behavior of CREATEROLE to the degree\\nsuggested here. However, there are three choices here, only one of which\\ncan be chosen:\\n\\n1. Leave CREATEROLE alone entirely\\n2. Make it so CREATEROLE cannot assign membership to the predefined roles\\nor superuser (inheritance included), but leave the rest alone. This would\\nbe the hard-coded version, not the role attribute one.\\n3. Make it so CREATEROLE can only assign membership to roles for which it\\nhas been made an admin; as well as the other things mentioned\\n\\nMoving forward I'd prefer options 1 or 2, leaving the ability to\\ncreate/alter/drop a role to be vested via predefined roles.\\n\\nThe rest seems fine at an initial glance.\\n\\nDavid J.\\n\\nOn Thu, Mar 10, 2022 at 12:58 PM Stephen Frost <sfrost@snowman.net> wrote:I don't think we're that far from having all of these though. To start\\nwith, we remove from CREATEROLE the random things that it does which go\\nbeyond what folks tend to expect- remove the whole 'grant any role to\\nany other' stuff, remove the 'drop role' exception, remove the\\n'alter role' stuff. Do make it so that when you create a role, however,\\nthe above GRANT is effectively done. Now, for the items above where we\\nremoved the checks against have_createrole_privilege() we go back and\\nadd in checks using is_admin_of_role(). Of course, also remove the role\\nself-administration bug.\\n\\nThat's step #1, but it gets us more-or-less what you're looking for, I\\nthink, and brings us a lot closer to what the spec has.That still leaves attribute specification in place: e.g., REPLICATION, CREATEROLE, CREATEDB, etc... (I see BYPASSRLS already is SUPERUSER only)I dislike changing the documented behavior of CREATEROLE to the degree suggested here. However, there are three choices here, only one of which can be chosen:1. Leave CREATEROLE alone entirely2. Make it so CREATEROLE cannot assign membership to the predefined roles or superuser (inheritance included), but leave the rest alone. This would be the hard-coded version, not the role attribute one.3. Make it so CREATEROLE can only assign membership to roles for which it has been made an admin; as well as the other things mentionedMoving forward I'd prefer options 1 or 2, leaving the ability to create/alter/drop a role to be vested via predefined roles.The rest seems fine at an initial glance.David J.\",\n \"msg_date\": \"Thu, 10 Mar 2022 14:00:41 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 3:41 PM Stephen Frost <sfrost@snowman.net> wrote:\\n> > Gosh, I feel like I've spelled that out approximately 463,121 times\\n> > already. That estimate might be slightly off though; I've been known\\n> > to make mistakes from time to time....\\n>\\n> If there's a specific message that details it closely on the lists\\n> somewhere, I'm happy to go review it. I admit that I didn't go back and\\n> look for such.\\n\\nProbably easier to just say it again: I want to have users that can\\ncreate roles and then have superuser-like powers with respect to those\\nroles. They can freely exercise the privileges of those roles, and\\nthey can do all the things that a superuser can do but only with\\nrespect to those roles. They cannot break out to the OS. I think it's\\npretty similar to what you are describing, with a couple of possible\\nexceptions. For example, would you imagine that being an admin of a\\nlogin role would let you change that user's password? Because that\\nwould be desirable behavior from where I sit.\\n\\n> Errr, just to be clear, ALTER ROLE doesn't exist *in the spec*. I\\n> wasn't suggesting that we get rid of it, just that it doesn't exist in\\n> the spec and therefore the spec doesn't have anything to say about it.\\n\\nOh, OK.\\n\\n> > Basically, in this sketch, ADMIN OPTION on a role involves the ability\\n> > to DROP it, which means we don't need a separate role owner concept.\\n>\\n> Right. The above doesn't include any specifics about what to do with\\n> ALTER ROLE, but my thought would be to have it also be under ADMIN\\n> OPTION rather than under CREATEROLE, as I tried to outline (though not\\n> very well, I'll admit) below.\\n\\nThis sentence really confused me at first, but I think you're saying\\nthat the right to alter a role would be dependent on having ADMIN\\nOPTION on the role rather than on having the CREATEROLE attribute.\\nThat seems like a reasonable idea to me.\\n\\n> > It also involves membership, meaning that you can freely exercise the\\n> > privileges of the role without SET ROLE. While I'm totally down with\\n> > having other possible behaviors as options, that particular behavior\\n> > seems very useful to me, so, sounds great.\\n>\\n> Well, yes and no- by default you're right, presuming everything is set\\n> as inheirited, but I'd wish for us to keep the option of creating roles\\n> which are noinherit and having that work just as it does today.\\n\\nHmm, so if I have membership WITH ADMIN OPTION in a role, but my role\\nis marked NOINHERIT, that means I can't exercise the privileges of\\nthat role without SET ROLE. But, can I still do other things to that\\nrole, such as dropping it? Given the current coding of\\nroles_is_member_of(), it seems like I can't. I don't like that, but\\nthen I don't like much of anything about NOINHERIT. Do you have any\\nsuggestions for how this could be improved?\\n\\nTo make this more concrete, suppose the superuser does \\\"CREATE USER\\nalice CREATEROLE\\\". Alice will have INHERIT, so she'll have control\\nover any roles she creates. But if she does \\\"CREATE USER bob\\nCREATEROLE NOINHERIT\\\" then neither she nor Bob will be able to control\\nthe roles bob creates. I'd like to have a way to make it so that\\nneither Alice nor any other CREATEROLE users she spins up can create\\nroles over which they no longer have control. Because otherwise people\\nwill do dumb stuff like that and then have to call the superuser to\\nsort it out, and the superuser won't like that because s/he is a super\\nbusy person.\\n\\n> > What do you mean by the 'drop role' exception?\\n>\\n> 'ability' was probably a better word there. What I'm talking about is\\n> changing in DropRole:\\n>\\n> to be, more or less:\\n>\\n> if (!is_admin_of_role(role))\\n> ereport(ERROR,\\n> (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n> errmsg(\\\"permission denied to drop role\\\")));\\n\\nSounds good.\\n\\n> > I don't like removing 'alter role'.\\n>\\n> Ditto above but for AlterRole. Taking it away from users with\\n> CREATEROLE being able to run those commands on $anyrole and instead\\n> making it so that the role running DROP ROLE or ALTER ROLE needs to have\\n> ADMIN on the role they're messing with. I do think we may also need to\\n> make some adjustments in terms of what a regular user WITH ADMIN on a\\n> given role is able to do when it comes to ALTER ROLE, in particular, I\\n> don't think we'll want to remove the existing is-superuser checks\\n> against a user settings bypassrls or replication or superuser on some\\n> other role. Maybe we can provide a way for a non-superuser to be given\\n> the ability to set those attributes for roles they create, but that\\n> would be a separate thing.\\n\\nThis too.\\n\\n> > > Step #2 is also in-line with the spec: track GRANTORs and care about\\n> > > them, for everything. We really should have been doing this all along.\\n> >\\n> > There are details to work out here, but in general, I like it.\\n>\\n> Cool. Note that superusers would still be able to do $anything,\\n> including removing someone's ADMIN rights on a role even if that\\n> superuser didn't GRANT it (at least, that's my thinking on this).\\n\\nAgree. I also think that it would be a good idea to attribute grants\\nperformed by any superuser to the bootstrap superuser, or leave them\\nunattributed somehow. Because otherwise dropping superusers becomes a\\npain in the tail for no good reason.\\n\\nWe might also need to think carefully about what happens if for\\nexample the table owner is changed. If bob owns the table and we\\nchange the owner to mary, but bob's previous grants are still\\nattributed to bob, I'm not sure that's going to be very convenient.\\nPossibly if the table owner changes we also change the owner of all\\ngrants attributed to the old table owner to be attributed to the new\\ntable owner?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 16:51:01 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 02:22:05PM -0500, Robert Haas wrote:\\n> I mean, I didn't design pg_hba.conf, but I think it's part of the\\n> database doing a reasonable thing, not an external system doing a\\n> nonsensical thing.\\n\\nFYI, I think pg_hba.conf gets away with having negative/reject\\npermissions only because it is strictly ordered.\\n\\n-- \\n Bruce Momjian <bruce@momjian.us> https://momjian.us\\n EDB https://enterprisedb.com\\n\\n If only the physical world exists, free will is an illusion.\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 17:00:11 -0500\",\n \"msg_from\": \"Bruce Momjian <bruce@momjian.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 4:00 PM David G. Johnston\\n<david.g.johnston@gmail.com> wrote:\\n> I dislike changing the documented behavior of CREATEROLE to the degree suggested here. However, there are three choices here, only one of which can be chosen:\\n>\\n> 1. Leave CREATEROLE alone entirely\\n> 2. Make it so CREATEROLE cannot assign membership to the predefined roles or superuser (inheritance included), but leave the rest alone. This would be the hard-coded version, not the role attribute one.\\n> 3. Make it so CREATEROLE can only assign membership to roles for which it has been made an admin; as well as the other things mentioned\\n>\\n> Moving forward I'd prefer options 1 or 2, leaving the ability to create/alter/drop a role to be vested via predefined roles.\\n\\nIt sounds like you prefer a behavior where CREATEROLE gives power over\\nall non-superusers, but that seems pretty limiting to me. Why can't\\nsomeone want to create a user with power over some users but not\\nothers? For example, the superuser might want to give alice the\\nability to set up new users in the accounting department, but NOT give\\nalice the right to tinker with the backup user (who is not a\\nsuperuser, but doesn't have the replication privilege). How would they\\naccomplish that in your view?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 17:01:43 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 5:00 PM Bruce Momjian <bruce@momjian.us> wrote:\\n> On Thu, Mar 10, 2022 at 02:22:05PM -0500, Robert Haas wrote:\\n> > I mean, I didn't design pg_hba.conf, but I think it's part of the\\n> > database doing a reasonable thing, not an external system doing a\\n> > nonsensical thing.\\n>\\n> FYI, I think pg_hba.conf gets away with having negative/reject\\n> permissions only because it is strictly ordered.\\n\\nI agree.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 17:02:05 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 3:01 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n\\n> On Thu, Mar 10, 2022 at 4:00 PM David G. Johnston\\n> <david.g.johnston@gmail.com> wrote:\\n> > I dislike changing the documented behavior of CREATEROLE to the degree\\n> suggested here. However, there are three choices here, only one of which\\n> can be chosen:\\n> >\\n> > 1. Leave CREATEROLE alone entirely\\n> > 2. Make it so CREATEROLE cannot assign membership to the predefined\\n> roles or superuser (inheritance included), but leave the rest alone. This\\n> would be the hard-coded version, not the role attribute one.\\n> > 3. Make it so CREATEROLE can only assign membership to roles for which\\n> it has been made an admin; as well as the other things mentioned\\n> >\\n> > Moving forward I'd prefer options 1 or 2, leaving the ability to\\n> create/alter/drop a role to be vested via predefined roles.\\n>\\n> It sounds like you prefer a behavior where CREATEROLE gives power over\\n> all non-superusers, but that seems pretty limiting to me.\\n>\\n\\nDoh! I edited out the part where I made clear I considered options 1 and 2\\nas basically being done for a limited period of time while deprecating the\\nCREATEROLE attribute altogether in favor of the fine-grained and predefined\\nrole based permission granting. I don't want to nerf CREATEROLE as part of\\nadding this new feature, instead leave it as close to status quo as\\nreasonable so as not to mess up existing setups that make use of it. We\\ncan note in the release notes and documentation that we consider CREATEROLE\\nto be deprecated and that the new predefined role should be used to give a\\nuser the ability to create/alter/drop roles, etc... DBAs should consider\\nrevoking CREATEROLE from their users and granting them proper memberships\\nin the predefined roles and the groups those roles should be administering.\\n\\nDavid J.\\n\\nOn Thu, Mar 10, 2022 at 3:01 PM Robert Haas <robertmhaas@gmail.com> wrote:On Thu, Mar 10, 2022 at 4:00 PM David G. Johnston\\n<david.g.johnston@gmail.com> wrote:\\n> I dislike changing the documented behavior of CREATEROLE to the degree suggested here. However, there are three choices here, only one of which can be chosen:\\n>\\n> 1. Leave CREATEROLE alone entirely\\n> 2. Make it so CREATEROLE cannot assign membership to the predefined roles or superuser (inheritance included), but leave the rest alone. This would be the hard-coded version, not the role attribute one.\\n> 3. Make it so CREATEROLE can only assign membership to roles for which it has been made an admin; as well as the other things mentioned\\n>\\n> Moving forward I'd prefer options 1 or 2, leaving the ability to create/alter/drop a role to be vested via predefined roles.\\n\\nIt sounds like you prefer a behavior where CREATEROLE gives power over\\nall non-superusers, but that seems pretty limiting to me.Doh! I edited out the part where I made clear I considered options 1 and 2 as basically being done for a limited period of time while deprecating the CREATEROLE attribute altogether in favor of the fine-grained and predefined role based permission granting. I don't want to nerf CREATEROLE as part of adding this new feature, instead leave it as close to status quo as reasonable so as not to mess up existing setups that make use of it. We can note in the release notes and documentation that we consider CREATEROLE to be deprecated and that the new predefined role should be used to give a user the ability to create/alter/drop roles, etc... DBAs should consider revoking CREATEROLE from their users and granting them proper memberships in the predefined roles and the groups those roles should be administering.David J.\",\n \"msg_date\": \"Thu, 10 Mar 2022 15:12:27 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> Probably easier to just say it again: I want to have users that can\\n> create roles and then have superuser-like powers with respect to those\\n> roles. They can freely exercise the privileges of those roles, and\\n> they can do all the things that a superuser can do but only with\\n> respect to those roles.\\n\\nThis seems reasonable in isolation, but\\n\\n(1) it implies a persistent relationship between creating and created\\nroles. Whether you want to call that ownership or not, it sure walks\\nand quacks like ownership.\\n\\n(2) it seems exactly contradictory to your later point that\\n\\n> Agree. I also think that it would be a good idea to attribute grants\\n> performed by any superuser to the bootstrap superuser, or leave them\\n> unattributed somehow. Because otherwise dropping superusers becomes a\\n> pain in the tail for no good reason.\\n\\nEither there's a persistent relationship or there's not. I don't\\nthink it's sensible to treat superusers differently here.\\n\\nI think that this argument about the difficulty of dropping superusers\\nmay in fact be the motivation for the existing behavior that object-\\npermissions GRANTs done by superusers are attributed to the object\\nowner; something you were unhappy about upthread.\\n\\nIn the end these requirements seem mutually contradictory. Either\\nwe can have a persistent ownership relationship or not, but I don't\\nthink we can have it apply in some cases and not others without\\ncreating worse problems than we solve. I'm inclined to toss overboard\\nthe requirement that superusers need to be an easy thing to drop.\\nWhy is that important, anyway?\\n\\n> We might also need to think carefully about what happens if for\\n> example the table owner is changed. If bob owns the table and we\\n> change the owner to mary, but bob's previous grants are still\\n> attributed to bob, I'm not sure that's going to be very convenient.\\n\\nThat's already handled, is it not?\\n\\nregression=# create user alice;\\nCREATE ROLE\\nregression=# create user bob;\\nCREATE ROLE\\nregression=# create user charlie;\\nCREATE ROLE\\nregression=# \\\\c - alice\\nYou are now connected to database \\\"regression\\\" as user \\\"alice\\\".\\nregression=> create table alices_table (f1 int);\\nCREATE TABLE\\nregression=> grant select on alices_table to bob;\\nGRANT\\nregression=> \\\\c - postgres\\nYou are now connected to database \\\"regression\\\" as user \\\"postgres\\\".\\nregression=# alter table alices_table owner to charlie;\\nALTER TABLE\\nregression=# \\\\dp alices_table\\n Access privileges\\n Schema | Name | Type | Access privileges | Column privileges | Policies \\n--------+--------------+-------+-------------------------+-------------------+----------\\n public | alices_table | table | charlie=arwdDxt/charlie+| | \\n | | | bob=r/charlie | | \\n(1 row)\\n\\nI'm a bit disturbed that parts of this discussion seem to be getting\\nconducted with little understanding of the system's existing behaviors.\\nWe should not be reinventing things we already have perfectly good\\nsolutions for in the object-privileges domain.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 17:14:36 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 10, 2022, at 2:01 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> It sounds like you prefer a behavior where CREATEROLE gives power over\\n> all non-superusers, but that seems pretty limiting to me. Why can't\\n> someone want to create a user with power over some users but not\\n> others?\\n\\nI agree with Robert on this.\\n\\nOver at [1], I introduced a patch series to (a) change CREATEROLE and (b) introduce role ownership. Part (a) wasn't that controversial. The patch series failed to make it for postgres 15 on account of (b). The patch didn't go quite far enough, but with it applied, this is an example of a min-superuser \\\"lord\\\" operating within database \\\"fiefdom\\\":\\n\\nfiefdom=# -- mini-superuser who can create roles and write all data\\nfiefdom=# CREATE ROLE lord\\nfiefdom-# WITH CREATEROLE\\nfiefdom-# IN ROLE pg_write_all_data;\\nCREATE ROLE\\nfiefdom=# \\nfiefdom=# -- group which \\\"lord\\\" belongs to\\nfiefdom=# CREATE GROUP squire\\nfiefdom-# ROLE lord;\\nCREATE ROLE\\nfiefdom=# \\nfiefdom=# -- group which \\\"lord\\\" has no connection to\\nfiefdom=# CREATE GROUP paladin;\\nCREATE ROLE\\nfiefdom=# \\nfiefdom=# SET SESSION AUTHORIZATION lord;\\nSET\\nfiefdom=> \\nfiefdom=> -- fail, merely a member of \\\"squire\\\"\\nfiefdom=> CREATE ROLE peon IN ROLE squire;\\nERROR: must have admin option on role \\\"squire\\\"\\nfiefdom=> \\nfiefdom=> -- fail, no privilege to grant CREATEDB \\nfiefdom=> CREATE ROLE peon CREATEDB;\\nERROR: must have createdb privilege to create createdb users\\nfiefdom=> \\nfiefdom=> RESET SESSION AUTHORIZATION;\\nRESET\\nfiefdom=# \\nfiefdom=# -- grant admin over \\\"squire\\\" to \\\"lord\\\"\\nfiefdom=# GRANT squire\\nfiefdom-# TO lord\\nfiefdom-# WITH ADMIN OPTION;\\nGRANT ROLE\\nfiefdom=# \\nfiefdom=# SET SESSION AUTHORIZATION lord;\\nSET\\nfiefdom=> \\nfiefdom=> -- ok, have both \\\"CREATEROLE\\\" and admin option for \\\"squire\\\"\\nfiefdom=> CREATE ROLE peon IN ROLE squire;\\nCREATE ROLE\\nfiefdom=> \\nfiefdom=> -- fail, no privilege to grant CREATEDB\\nfiefdom=> CREATE ROLE peasant CREATEDB IN ROLE squire;\\nERROR: must have createdb privilege to create createdb users\\nfiefdom=> \\nfiefdom=> RESET SESSION AUTHORIZATION;\\nRESET\\nfiefdom=# \\nfiefdom=# -- Give lord the missing privilege\\nfiefdom=# GRANT CREATEDB TO lord;\\nERROR: role \\\"createdb\\\" does not exist\\nfiefdom=# \\nfiefdom=# RESET SESSION AUTHORIZATION;\\nRESET\\nfiefdom=# \\nfiefdom=# -- ok, have \\\"CREATEROLE\\\", \\\"CREATEDB\\\", and admin option for \\\"squire\\\"\\nfiefdom=# CREATE ROLE peasant CREATEDB IN ROLE squire;\\nCREATE ROLE\\n\\nThe problem with this is that \\\"lord\\\" needs CREATEDB to grant CREATEDB, but really it should need something like grant option on \\\"CREATEDB\\\". But that's hard to do with the existing system, given the way these privilege bits are represented. If we added a few more built-in pg_* roles, such as pg_create_db, it would just work. CREATEROLE itself could be reimagined as pg_create_role, and then users could be granted into this role with or without admin option, meaning they could/couldn't further give it away. I think that would be a necessary component to Joshua's \\\"bot\\\" use-case, since the bot must itself have the privilege to create roles, but shouldn't necessarily be trusted with the privilege to create additional roles who have it.\\n\\n[1] https://www.postgresql.org/message-id/53C7DF4C-8463-4647-9DFD-779B5E1861C4@amazon.com\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 14:17:08 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 10, 2022 at 5:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> This seems reasonable in isolation, but\\n>\\n> (1) it implies a persistent relationship between creating and created\\n> roles. Whether you want to call that ownership or not, it sure walks\\n> and quacks like ownership.\\n\\nI agree. It's been obvious to me from the beginning that we needed\\nsuch a persistent relationship, and also that it needed to be a\\nrelationship from which the created role couldn't simply walk away.\\nYet, more than six months after the first discussions of this topic,\\nwe still don't have any kind of agreement on what that thing should be\\ncalled. I like my TENANT idea best, but I'm perfectly willing to call\\nit ownership as you seem to prefer or WITH ADMIN OPTION as Stephen\\nseems to prefer if one of those ideas gains consensus. But we've\\nmanaged to waste all hope of making any significant progress here for\\nan entire release cycle for lack of ability to agree on spelling. I\\nthink that's unfair to Mark, who put a lot of work into this area and\\ngot nothing out of it, and I think it sucks for users of PostgreSQL,\\ntoo.\\n\\n> (2) it seems exactly contradictory to your later point that\\n>\\n> > Agree. I also think that it would be a good idea to attribute grants\\n> > performed by any superuser to the bootstrap superuser, or leave them\\n> > unattributed somehow. Because otherwise dropping superusers becomes a\\n> > pain in the tail for no good reason.\\n>\\n> Either there's a persistent relationship or there's not. I don't\\n> think it's sensible to treat superusers differently here.\\n>\\n> I think that this argument about the difficulty of dropping superusers\\n> may in fact be the motivation for the existing behavior that object-\\n> permissions GRANTs done by superusers are attributed to the object\\n> owner; something you were unhappy about upthread.\\n>\\n> In the end these requirements seem mutually contradictory. Either\\n> we can have a persistent ownership relationship or not, but I don't\\n> think we can have it apply in some cases and not others without\\n> creating worse problems than we solve. I'm inclined to toss overboard\\n> the requirement that superusers need to be an easy thing to drop.\\n> Why is that important, anyway?\\n\\nWell, I think you're looking at it the wrong way. Compared to getting\\nuseful functionality, the relative ease of dropping users is\\ncompletely unimportant. I'm happy to surrender it in exchange for\\nsomething else. I just don't see why we should give it up for nothing.\\nIf Alice creates non-superusers Bob and Charlie, and Charlie creates\\nDoug, we need the persistent relationship to know that Charlie is\\nallowed to drop Doug and Bob is not. But if Charlie is a superuser\\nanyway, then the persistent relationship is of no use. I don't see the\\npoint of cluttering up the system with such dependencies. Will I do it\\nthat way, if that's what it takes to get the patch accepted? Sure. But\\nI can't imagine any end-user actually liking it.\\n\\n> I'm a bit disturbed that parts of this discussion seem to be getting\\n> conducted with little understanding of the system's existing behaviors.\\n> We should not be reinventing things we already have perfectly good\\n> solutions for in the object-privileges domain.\\n\\nI did wonder whether that might be the existing behavior, but stopping\\nto check right at that moment didn't seem that important to me. Maybe\\nI should have taken the time, but it's not like we're writing the\\nfinal patch for commit next Tuesday at this point. It's more important\\nat this point to get agreement on the principles. That said, I do\\nagree that there have been times when we haven't thought hard enough\\nabout the existing behavior in proposing new behavior. On the third\\nhand, though, part of the problem here is that neither Stephen nor I\\nare entirely happy with the existing behavior, if for somewhat\\ndifferent reasons. It really isn't \\\"perfectly good.\\\" On the one hand,\\nfrom a purely technical standpoint, a lot of the behavior around roles\\nin particular seems well below the standard that anyone would consider\\ncommittable today. On the other hand, even the parts of the code that\\nare in reasonable shape from a code quality point of view don't\\nactually do the things that we think users want done.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 08:55:16 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Thu, Mar 10, 2022 at 5:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > This seems reasonable in isolation, but\\n> >\\n> > (1) it implies a persistent relationship between creating and created\\n> > roles. Whether you want to call that ownership or not, it sure walks\\n> > and quacks like ownership.\\n\\nI agree that there would be a recorded relationship (that is, one that\\nwe write into the catalog and keep around until and unless it's removed\\nby an admin) between creating and created roles and that's probably the\\ndefault when CREATE ROLE is run but, unlike tables or such objects in\\nthe system, I don't agree that we should require this to exist at\\nabsolutely all times for every role (what would it be for the bootstrap\\nsuperuser..?). At least today, that's distinct from how ownership in\\nthe system works. I also don't believe that this is necessarily an\\nissue for Robert's use-case, as long as there are appropriate\\nrestrictions around who is allowed to remove or modify these\\nrelationships.\\n\\n> I agree. It's been obvious to me from the beginning that we needed\\n> such a persistent relationship, and also that it needed to be a\\n> relationship from which the created role couldn't simply walk away.\\n> Yet, more than six months after the first discussions of this topic,\\n> we still don't have any kind of agreement on what that thing should be\\n> called. I like my TENANT idea best, but I'm perfectly willing to call\\n> it ownership as you seem to prefer or WITH ADMIN OPTION as Stephen\\n> seems to prefer if one of those ideas gains consensus. But we've\\n> managed to waste all hope of making any significant progress here for\\n> an entire release cycle for lack of ability to agree on spelling. I\\n> think that's unfair to Mark, who put a lot of work into this area and\\n> got nothing out of it, and I think it sucks for users of PostgreSQL,\\n> too.\\n\\nWell ... one of those actually already exists and also happens to be in\\nthe SQL spec. I don't necessarily agree that we should absolutely\\nrequire that the system always enforce that this relationship exist (I'd\\nlike a superuser to be able to get rid of it and to be able to change it\\ntoo if they want) and that seems a bit saner than having the bootstrap\\nsuperuser be special in some way here as would seem to otherwise be\\nrequired. I also feel that it would be generally useful to have more\\nthan one of these relationships, if the user wishes, and that's\\nsomething that ownership doesn't (directly) support today. Further,\\nthat's supported and expected by the SQL spec too. Even if we invented\\nsome concept of ownership of roles, it seems like we should make most of\\nthe other changes discussed here to bring us closer to what the spec\\nsays about CREATE ROLE, DROP ROLE, GRANT, REVOKE, etc. At that point\\nthough, what's the point of having ownership?\\n\\n> > (2) it seems exactly contradictory to your later point that\\n> >\\n> > > Agree. I also think that it would be a good idea to attribute grants\\n> > > performed by any superuser to the bootstrap superuser, or leave them\\n> > > unattributed somehow. Because otherwise dropping superusers becomes a\\n> > > pain in the tail for no good reason.\\n> >\\n> > Either there's a persistent relationship or there's not. I don't\\n> > think it's sensible to treat superusers differently here.\\n> >\\n> > I think that this argument about the difficulty of dropping superusers\\n> > may in fact be the motivation for the existing behavior that object-\\n> > permissions GRANTs done by superusers are attributed to the object\\n> > owner; something you were unhappy about upthread.\\n> >\\n> > In the end these requirements seem mutually contradictory. Either\\n> > we can have a persistent ownership relationship or not, but I don't\\n> > think we can have it apply in some cases and not others without\\n> > creating worse problems than we solve. I'm inclined to toss overboard\\n> > the requirement that superusers need to be an easy thing to drop.\\n> > Why is that important, anyway?\\n> \\n> Well, I think you're looking at it the wrong way. Compared to getting\\n> useful functionality, the relative ease of dropping users is\\n> completely unimportant. I'm happy to surrender it in exchange for\\n> something else. I just don't see why we should give it up for nothing.\\n> If Alice creates non-superusers Bob and Charlie, and Charlie creates\\n> Doug, we need the persistent relationship to know that Charlie is\\n> allowed to drop Doug and Bob is not. But if Charlie is a superuser\\n> anyway, then the persistent relationship is of no use. I don't see the\\n> point of cluttering up the system with such dependencies. Will I do it\\n> that way, if that's what it takes to get the patch accepted? Sure. But\\n> I can't imagine any end-user actually liking it.\\n\\nWe need to know that Charlie is allowed to drop Doug and Bob isn't but\\nthat doesn't make it absolutely required that this be tracked\\npermanently or that Alice can't decide later to make it such that Doug\\ncan't be dropped by Charlie for whatever reason she has. Also, I don't\\nthink it would be such an issue to have a CASCADE for DROP ROLE which\\nwould handle this case if we want it (and pg_auth_members is shared, so\\nthere isn't an issue with multi-database concerns). We could also call\\nit something else if people feel CASCADE would be confusing since it\\nwouldn't cascade to owned objects. Or we could consider extending GRANT\\nto make this situation something that could be handled more easily.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 10:27:52 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 6:55 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n\\n> On Thu, Mar 10, 2022 at 5:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > This seems reasonable in isolation, but\\n> >\\n> > (1) it implies a persistent relationship between creating and created\\n> > roles. Whether you want to call that ownership or not, it sure walks\\n> > and quacks like ownership.\\n>\\n\\n\\n> I like my TENANT idea best, but I'm perfectly willing to call\\n> it ownership as you seem to prefer or WITH ADMIN OPTION as Stephen\\n> seems to prefer if one of those ideas gains consensus.\\n\\n\\nIf WITH ADMIN OPTION is sufficient to meet our immediate goals I do not see\\nthe benefit of adding an ownership concept where there is not one today.\\nIf added, I'd much rather have it be ownership as to fit in with the rest\\nof the existing system rather than introduce an entirely new term.\\n\\n\\n> If Alice creates non-superusers Bob and Charlie, and Charlie creates\\n> Doug, we need the persistent relationship to know that Charlie is\\n> allowed to drop Doug and Bob is not\\n>\\n\\nThe interesting question seems to be whether Alice can drop Doug, not\\nwhether Bob can.\\n\\n> It's more important\\n> at this point to get agreement on the principles.\\n>\\n\\nWhat are the principles you want to get agreement on and how do they differ\\nfrom what we have in place today? What are the proposed changes you would\\nmake to enforce the new principles. Which principles are now obsolete and\\nwhat do you want to do about the features that were built to enforce them\\n(including backward compatibility concerns)?\\n\\nDavid J.\\n\\nOn Fri, Mar 11, 2022 at 6:55 AM Robert Haas <robertmhaas@gmail.com> wrote:On Thu, Mar 10, 2022 at 5:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> This seems reasonable in isolation, but\\n>\\n> (1) it implies a persistent relationship between creating and created\\n> roles. Whether you want to call that ownership or not, it sure walks\\n> and quacks like ownership. I like my TENANT idea best, but I'm perfectly willing to call\\nit ownership as you seem to prefer or WITH ADMIN OPTION as Stephen\\nseems to prefer if one of those ideas gains consensus.If WITH ADMIN OPTION is sufficient to meet our immediate goals I do not see the benefit of adding an ownership concept where there is not one today. If added, I'd much rather have it be ownership as to fit in with the rest of the existing system rather than introduce an entirely new term.\\nIf Alice creates non-superusers Bob and Charlie, and Charlie creates\\nDoug, we need the persistent relationship to know that Charlie is\\nallowed to drop Doug and Bob is notThe interesting question seems to be whether Alice can drop Doug, not whether Bob can.It's more important\\nat this point to get agreement on the principles.What are the principles you want to get agreement on and how do they differ from what we have in place today? What are the proposed changes you would make to enforce the new principles. Which principles are now obsolete and what do you want to do about the features that were built to enforce them (including backward compatibility concerns)?David J.\",\n \"msg_date\": \"Fri, 11 Mar 2022 08:27:56 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* David G. Johnston (david.g.johnston@gmail.com) wrote:\\n> On Thu, Mar 10, 2022 at 3:01 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> > On Thu, Mar 10, 2022 at 4:00 PM David G. Johnston\\n> > <david.g.johnston@gmail.com> wrote:\\n> > > I dislike changing the documented behavior of CREATEROLE to the degree\\n> > suggested here. However, there are three choices here, only one of which\\n> > can be chosen:\\n> > >\\n> > > 1. Leave CREATEROLE alone entirely\\n> > > 2. Make it so CREATEROLE cannot assign membership to the predefined\\n> > roles or superuser (inheritance included), but leave the rest alone. This\\n> > would be the hard-coded version, not the role attribute one.\\n> > > 3. Make it so CREATEROLE can only assign membership to roles for which\\n> > it has been made an admin; as well as the other things mentioned\\n> > >\\n> > > Moving forward I'd prefer options 1 or 2, leaving the ability to\\n> > create/alter/drop a role to be vested via predefined roles.\\n> >\\n> > It sounds like you prefer a behavior where CREATEROLE gives power over\\n> > all non-superusers, but that seems pretty limiting to me.\\n> \\n> Doh! I edited out the part where I made clear I considered options 1 and 2\\n> as basically being done for a limited period of time while deprecating the\\n> CREATEROLE attribute altogether in favor of the fine-grained and predefined\\n> role based permission granting. I don't want to nerf CREATEROLE as part of\\n> adding this new feature, instead leave it as close to status quo as\\n> reasonable so as not to mess up existing setups that make use of it. We\\n> can note in the release notes and documentation that we consider CREATEROLE\\n> to be deprecated and that the new predefined role should be used to give a\\n> user the ability to create/alter/drop roles, etc... DBAs should consider\\n> revoking CREATEROLE from their users and granting them proper memberships\\n> in the predefined roles and the groups those roles should be administering.\\n\\nI disagree entirely with the idea that we should push the out however\\nmany years it'd take to get through some deprecation period. We are\\nabsolutely terrible when it comes to that and what we're talking about\\nhere, at this point anyway, is making changes that get us closer to what\\nthe spec says. I agree that we can't back-patch these changes, but I\\ndon't think we need a deprecation period. If we were just getting rid\\nof CREATEROLE, I don't think we'd have a deprecation period. If we need\\nto get rid of CREATEROLE and introduce something new that more-or-less\\nmeans the same thing, to make it so that people's scripts break in a\\nmore obvious way, maybe we can consider that, but I don't really think\\nthat's actually the case here. Such scripts as will break will still\\nbreak in a pretty clear way with a clear answer as to how to fix them\\nand I don't think there's some kind of data corruption or something that\\nwould happen.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 10:32:07 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 8:32 AM Stephen Frost <sfrost@snowman.net> wrote:\\n\\n>\\n> Such scripts as will break will still\\n> break in a pretty clear way with a clear answer as to how to fix them\\n> and I don't think there's some kind of data corruption or something that\\n> would happen.\\n>\\n>\\nI largely agree and am perfectly fine with going with the majority on this\\npoint. My vote would just fall on the conservative side. But as so far no\\none else seems to be overly concerned, nerfing CREATEROLE seems to be the\\npath forward.\\n\\nDavid J.\\n\\nOn Fri, Mar 11, 2022 at 8:32 AM Stephen Frost <sfrost@snowman.net> wrote:Such scripts as will break will still\\nbreak in a pretty clear way with a clear answer as to how to fix them\\nand I don't think there's some kind of data corruption or something that\\nwould happen.I largely agree and am perfectly fine with going with the majority on this point. My vote would just fall on the conservative side. But as so far no one else seems to be overly concerned, nerfing CREATEROLE seems to be the path forward.David J.\",\n \"msg_date\": \"Fri, 11 Mar 2022 08:36:44 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 10:27 AM Stephen Frost <sfrost@snowman.net> wrote:\\n> I agree that there would be a recorded relationship (that is, one that\\n> we write into the catalog and keep around until and unless it's removed\\n> by an admin) between creating and created roles and that's probably the\\n> default when CREATE ROLE is run but, unlike tables or such objects in\\n> the system, I don't agree that we should require this to exist at\\n> absolutely all times for every role (what would it be for the bootstrap\\n> superuser..?). At least today, that's distinct from how ownership in\\n> the system works. I also don't believe that this is necessarily an\\n> issue for Robert's use-case, as long as there are appropriate\\n> restrictions around who is allowed to remove or modify these\\n> relationships.\\n\\nI agree.\\n\\n> > I agree. [ but we need to get consensus ]\\n>\\n> Well ... [ how about we do it my way? ]\\n\\nRepeating the same argument over again isn't necessarily going to help\\nanything here. I read your argument and I can believe there could be a\\nsolution along those lines, although you haven't addressed my concern\\nabout NOINHERIT. Tom is apparently less convinced, and you know, I\\nthink that's OK. Not everybody has to agree with the way you want to\\ndo it.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 10:41:17 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Fri, Mar 11, 2022 at 10:27 AM Stephen Frost <sfrost@snowman.net> wrote:\\n>> I agree that there would be a recorded relationship (that is, one that\\n>> we write into the catalog and keep around until and unless it's removed\\n>> by an admin) between creating and created roles and that's probably the\\n>> default when CREATE ROLE is run but, unlike tables or such objects in\\n>> the system, I don't agree that we should require this to exist at\\n>> absolutely all times for every role (what would it be for the bootstrap\\n>> superuser..?). At least today, that's distinct from how ownership in\\n>> the system works. I also don't believe that this is necessarily an\\n>> issue for Robert's use-case, as long as there are appropriate\\n>> restrictions around who is allowed to remove or modify these\\n>> relationships.\\n\\n> I agree.\\n\\nThe bootstrap superuser clearly must be a special case in some way.\\nI'm not convinced that that means there should be other special\\ncases. Maybe there is a use-case for other \\\"unowned\\\" roles, but in\\nexactly what way would that be different from deeming such roles\\nto be owned by the bootstrap superuser?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 10:46:55 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 10:37 AM David G. Johnston\\n<david.g.johnston@gmail.com> wrote:\\n> I largely agree and am perfectly fine with going with the majority on this point. My vote would just fall on the conservative side. But as so far no one else seems to be overly concerned, nerfing CREATEROLE seems to be the path forward.\\n\\nThis kind of thing is always a judgement call. If we were talking\\nabout breaking 'SELECT * from table', I'm sure it would be hard to\\nconvince anybody to agree to do that at all, let alone with no\\ndeprecation period. Fortunately, CREATEROLE is less used, so breaking\\nit will inconvenience fewer people. Moreover, unlike 'SELECT * FROM\\ntable', CREATEROLE is kinda broken, and it's less scary to make\\nchanges to behavior that sucks in the first place than it is to make\\nchanges to the behavior of things that are working well. For all of\\nthat, there's no hard-and-fast rule that we couldn't keep the existing\\nbehavior around, introduce a substitute, and eventually drop the old\\nthing. I'm just not clear that it's really worth it in this case. It'd\\ncertainly be interesting to hear from anyone who is finding some\\nutility in the current system. It looks pretty crap to me, but it's\\neasy to bring too much of one's own bias to such judgements.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 10:58:18 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 11, 2022, at 7:58 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> This kind of thing is always a judgement call. If we were talking\\n> about breaking 'SELECT * from table', I'm sure it would be hard to\\n> convince anybody to agree to do that at all, let alone with no\\n> deprecation period. Fortunately, CREATEROLE is less used, so breaking\\n> it will inconvenience fewer people.\\n\\nThis issue of how much backwards compatibility breakage we're willing to tolerate is just as important as questions about how we would want roles to work in a green-field development project. The sense I got a year ago, on this list, was that changing CREATEROLE was acceptable, but changing other parts of the system, such as how ADMIN OPTION works, would go too far.\\n\\nRole ownership did not yet exist, and that was a big motivation in introducing that concept, because you couldn't credibly say it broke other existing features. It introduces the new notion that when a superuser creates a role, the superuser owns it, which is identical to how things implicitly work today; and when a CREATEROLE non-superuser creates a role, that role owns the new role, which is different from how it works today, arguably breaking CREATEROLE's prior behavior. *But it doesn't break anything else*.\\n\\nIf we're going to change how ADMIN OPTION works, or how role membership works, or how inherit/noinherit works, let's first be clear that we are willing to accept whatever backwards incompatibility that entails. This is not a green-field development project. The constant spinning around with regard to how much compatibility we need to preserve is giving me vertigo.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 08:12:03 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 10:46 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> The bootstrap superuser clearly must be a special case in some way.\\n> I'm not convinced that that means there should be other special\\n> cases. Maybe there is a use-case for other \\\"unowned\\\" roles, but in\\n> exactly what way would that be different from deeming such roles\\n> to be owned by the bootstrap superuser?\\n\\nI think that just boils down to how many useless catalog entries you\\nwant to make.\\n\\nIf we implement the link between the creating role and the created\\nrole as role ownership, then we are surely just going to add a\\nrolowner column to pg_authid, and when the role is owned by nobody, I\\nthink we should always just store a valid OID in it, rather than\\nsometimes storing 0. It just seems simpler. Any time we would store 0,\\nstore the bootstrap superuser's pg_authid.oid value instead. That way\\nthe OID is always valid, which probably lets us get by with fewer\\nspecial cases in the code.\\n\\nIf we implement the link between the creating role and the created\\nrole as an automatically-granted WITH ADMIN OPTION, then we could\\nchoose to put (CREATOR_OID, CREATED_OID, whatever, TRUE) into\\npg_auth_members for the creating superuser or, indeed, every superuser\\nin the system. Or we can leave it out. The result will be exactly the\\nsame. Here, I would favor leaving it out, because extra catalog\\nentries that don't do anything are usually a thing that we do not\\nwant. See a49d081235997c67e8aab7a523b17e8d1cb93184, for example.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:13:00 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> If we implement the link between the creating role and the created\\n> role as role ownership, then we are surely just going to add a\\n> rolowner column to pg_authid, and when the role is owned by nobody, I\\n> think we should always just store a valid OID in it, rather than\\n> sometimes storing 0. It just seems simpler. Any time we would store 0,\\n> store the bootstrap superuser's pg_authid.oid value instead. That way\\n> the OID is always valid, which probably lets us get by with fewer\\n> special cases in the code.\\n\\n+1.\\n\\nNote that either case would also involve making entries in pg_shdepend;\\nalthough for the case of roles owned by/granted to the bootstrap\\nsuperuser, we could omit those on the usual grounds that we don't need\\nto record dependencies on pinned objects.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:34:36 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 11:12 AM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> This issue of how much backwards compatibility breakage we're willing to tolerate is just as important as questions about how we would want roles to work in a green-field development project. The sense I got a year ago, on this list, was that changing CREATEROLE was acceptable, but changing other parts of the system, such as how ADMIN OPTION works, would go too far.\\n>\\n> Role ownership did not yet exist, and that was a big motivation in introducing that concept, because you couldn't credibly say it broke other existing features. It introduces the new notion that when a superuser creates a role, the superuser owns it, which is identical to how things implicitly work today; and when a CREATEROLE non-superuser creates a role, that role owns the new role, which is different from how it works today, arguably breaking CREATEROLE's prior behavior. *But it doesn't break anything else*.\\n>\\n> If we're going to change how ADMIN OPTION works, or how role membership works, or how inherit/noinherit works, let's first be clear that we are willing to accept whatever backwards incompatibility that entails. This is not a green-field development project. The constant spinning around with regard to how much compatibility we need to preserve is giving me vertigo.\\n\\nI mean, I agree that the backward compatibility ramifications of every\\nidea need to be considered, but I agree even more that the amount of\\nspinning around here is pretty insane. My feeling is that neither role\\nowners nor tenants introduce any real concerns about\\nbackward-compatibility or, for that matter, SQL standards compliance,\\nnonwithstanding Stephen's argument to the contrary. Every vendor\\nextends the standard with their own stuff, and we've done that as\\nwell, as we can do it in more places.\\n\\nOn the other hand, changing ADMIN OPTION does have compatibility and\\nspec-compliance ramifications. I think Stephen is arguing that we can\\nsolve this problem while coming closer to the spec, and I think we\\nusually consider getting closer to the spec to be a sufficient reason\\nfor breaking backward compatibility (cf. standard_conforming_strings).\\nBut I don't know whether he is correct when he argues that the spec\\nmakes admin option on a role sufficient to drop the role. I've never\\nhad any luck understanding what the SQL specification is saying about\\nany topic.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:36:21 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Tom Lane (tgl@sss.pgh.pa.us) wrote:\\n> Robert Haas <robertmhaas@gmail.com> writes:\\n> > If we implement the link between the creating role and the created\\n> > role as role ownership, then we are surely just going to add a\\n> > rolowner column to pg_authid, and when the role is owned by nobody, I\\n> > think we should always just store a valid OID in it, rather than\\n> > sometimes storing 0. It just seems simpler. Any time we would store 0,\\n> > store the bootstrap superuser's pg_authid.oid value instead. That way\\n> > the OID is always valid, which probably lets us get by with fewer\\n> > special cases in the code.\\n\\nWe haven't got any particularly special cases in the code today for what\\nhappens if we run up the role hierarchy to a point that it ends and so\\nI'm not sure why adding in a whole new concept around role ownership,\\nwhich doesn't exist in the spec, would somehow leave us with fewer such\\nspecial cases.\\n\\n> +1.\\n> \\n> Note that either case would also involve making entries in pg_shdepend;\\n> although for the case of roles owned by/granted to the bootstrap\\n> superuser, we could omit those on the usual grounds that we don't need\\n> to record dependencies on pinned objects.\\n\\nThat we aren't discussing the issues with the current GRANT ... WITH\\nADMIN OPTION and how we deviate from what the spec calls for when it\\ncomes to DROP ROLE, which seems to be the largest thing that's\\n'solved' with this ownership concept, is concerning to me.\\n\\nIf we go down the route of adding role ownership, are we going to\\ndocument that we explicitly go against the SQL standard when it comes to\\nhow DROP ROLE works? Or are we going to fix DROP ROLE? I'd much prefer\\nthe latter, but doing so then largely negates the point of this role\\nownership concept. I don't see how it makes sense to do both.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:41:05 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Fri, Mar 11, 2022 at 11:12 AM Mark Dilger\\n> <mark.dilger@enterprisedb.com> wrote:\\n> > This issue of how much backwards compatibility breakage we're willing to tolerate is just as important as questions about how we would want roles to work in a green-field development project. The sense I got a year ago, on this list, was that changing CREATEROLE was acceptable, but changing other parts of the system, such as how ADMIN OPTION works, would go too far.\\n\\nThat we deviate as far as we do when it comes to the SQL spec is\\nsomething that I don't feel like I had a good handle on when discussing\\nthis previously (that the spec doesn't talk about 'admin option' really\\nbut rather 'grantable authorization identifiers' or whatever it is\\ndoesn't help... but still, that's on me, sorry about that).\\n\\n> > Role ownership did not yet exist, and that was a big motivation in introducing that concept, because you couldn't credibly say it broke other existing features. It introduces the new notion that when a superuser creates a role, the superuser owns it, which is identical to how things implicitly work today; and when a CREATEROLE non-superuser creates a role, that role owns the new role, which is different from how it works today, arguably breaking CREATEROLE's prior behavior. *But it doesn't break anything else*.\\n> >\\n> > If we're going to change how ADMIN OPTION works, or how role membership works, or how inherit/noinherit works, let's first be clear that we are willing to accept whatever backwards incompatibility that entails. This is not a green-field development project. The constant spinning around with regard to how much compatibility we need to preserve is giving me vertigo.\\n\\nI agree that it would have an impact on backwards compatibility to\\nchange how WITH ADMIN works- but it would also get us more in line with\\nwhat the SQL standard says for how WITH ADMIN is supposed to work and\\nthat seems worth the change to me.\\n\\n> On the other hand, changing ADMIN OPTION does have compatibility and\\n> spec-compliance ramifications. I think Stephen is arguing that we can\\n> solve this problem while coming closer to the spec, and I think we\\n> usually consider getting closer to the spec to be a sufficient reason\\n> for breaking backward compatibility (cf. standard_conforming_strings).\\n\\nIndeed.\\n\\n> But I don't know whether he is correct when he argues that the spec\\n> makes admin option on a role sufficient to drop the role. I've never\\n> had any luck understanding what the SQL specification is saying about\\n> any topic.\\n\\nI'm happy to point you to what the spec says and to discuss it further\\nif that would be helpful, or to get other folks to comment on it. I\\nagree that it's definitely hard to grok at times. In this particular\\ncase what I'm looking at is, under DROP ROLE / Access Rules, there's\\nonly one sentence:\\n\\nThere shall exist at least one grantable role authorization descriptor\\nwhose role name is R and whose grantee is an enabled authorization\\nidentifier.\\n\\nA bit of decoding: 'grantable role authorization descriptor' is a GRANT\\nof a role WITH ADMIN OPTION. The role name 'R' is the role specified.\\nThe 'grantee' is who that role R was GRANT'd to, and 'enabled\\nauthorization identifier' is basically \\\"has_privs_of_role()\\\" (note that\\nyou can in the spec hvae roles that you're a member of but which are\\n*not* currently enabled).\\n\\nHopefully that helps.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:48:08 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 11:34 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Note that either case would also involve making entries in pg_shdepend;\\n> although for the case of roles owned by/granted to the bootstrap\\n> superuser, we could omit those on the usual grounds that we don't need\\n> to record dependencies on pinned objects.\\n\\nThat makes sense to me, but it still doesn't solve the problem of\\nagreeing on role ownership vs. WITH ADMIN OPTION vs. something else.\\n\\nI find it ironic (and frustrating) that Mark implemented what I think\\nis basically what you're arguing for, it got stuck because Stephen\\ndidn't like it, we then said OK so let's try to find out what Stephen\\nwould like, only to have you show up and say that it's right the way\\nhe already had it. I'm not saying that you're wrong, or for that\\nmatter that he's wrong. I'm just saying that if both of you are\\nabsolutely bent on having it the way you want it, either one of you is\\ngoing to be sad, or we're not going to make any progress.\\n\\nNever mind the fact that neither of you seem interested in even giving\\na hearing to my preferred way of doing it. :-(\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 11:51:38 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 11, 2022, at 8:48 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> I agree that it would have an impact on backwards compatibility to\\n> change how WITH ADMIN works- but it would also get us more in line with\\n> what the SQL standard says for how WITH ADMIN is supposed to work and\\n> that seems worth the change to me.\\n\\nI'm fine with giving up some backwards compatibility to get some SQL standard compatibility, as long as we're clear that is what we're doing. What you say about the SQL spec isn't great, though, because too much power is vested in \\\"ADMIN\\\". I see \\\"ADMIN\\\" as at least three separate privileges together. Maybe it would be spec compliant to implement \\\"ADMIN\\\" as a synonym for a set of separate privileges? \\n\\n> On Mar 11, 2022, at 8:41 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> That we aren't discussing the issues with the current GRANT ... WITH\\n> ADMIN OPTION and how we deviate from what the spec calls for when it\\n> comes to DROP ROLE, which seems to be the largest thing that's\\n> 'solved' with this ownership concept, is concerning to me.\\n\\nSure, let's discuss that a bit more. Here is my best interpretation of your post about the spec, when applied to postgres with an eye towards not doing any more damage than necessary:\\n\\n> On Mar 10, 2022, at 11:58 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> let's look at what the spec says:\\n> \\n> CREATE ROLE\\n> - Who is allowed to run CREATE ROLE is implementation-defined\\n\\nThis should be anyone with membership in pg_create_role. \\n\\n> - After creation, this is effictively run:\\n> GRANT new_role TO creator_role WITH ADMIN, GRANTOR \\\"_SYSTEM\\\"\\n\\nThis should internally be implemented as three separate privileges, one which means you can grant the role, another which means you can drop the role, and a third that means you're a member of the role. That way, they can be independently granted and revoked. We could make \\\"WITH ADMIN\\\" a short-hand for \\\"WITH G, D, M\\\" where G, D, and M are whatever we name the independent privileges Grant, Drop, and Member-of.\\n\\nSplitting G and D helps with backwards compatibility, because it gives people who want the traditional postgres \\\"admin\\\" a way to get there, by granting \\\"G+M\\\". Splitting M from G and D makes it simpler to implement the \\\"bot\\\" idea, since the bot shouldn't have M. But it does raise a question about always granting G+D+M to the creator, since the bot is the creator and we don't want the bot to have M. This isn't a problem I've invented from thin air, mind you, as G+D+M is just the definition of ADMIN per the SQL spec, if I've understood you correctly. So we need to think a bit more about the pg_create_role built-in role and whether that needs to be further refined to distinguish those who can get membership in roles they create vs. those who cannot. This line of reasoning takes me in the direction of what I think you were calling #5 upthread, but you'd have to elaborate on that, and how it interacts with the spec, for us to have a useful conversation about it.\\n\\n> DROP ROLE\\n> - Any user who has been GRANT'd a role with ADMIN option is able to\\n> DROP that role.\\n\\nChange this to \\\"Any role who has D on the role\\\". That's spec compliant, because anyone granted ADMIN necessarily has D.\\n\\n> GRANT ROLE\\n> - No cycles allowed\\n> - A role must have ADMIN rights on the role to be able to GRANT it to\\n> another role.\\n\\nChange this to \\\"Any role who has G on the role\\\". That's spec compliant, because anyone grant ADMIN necessarily has G.\\n\\nWe should also fix the CREATE ROLE command to require the grantor have G on a role in order to give it to the new role as part of the command. Changing the CREATEROLE, CREATEDB, REPLICATION, and BYPASSRLS attributes into pg_create_role, pg_create_db, pg_replication, and pg_bypassrls, the creator could only give them to the created role if the creator has G on the roles. If we do this, we could keep the historical privilege bits and their syntax support for backward compatibility, or we could rip them out, but the decision between those two options is independent of the rest of the design.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 09:31:58 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\nOn Fri, Mar 11, 2022 at 12:32 Mark Dilger <mark.dilger@enterprisedb.com>\\nwrote:\\n\\n>\\n>\\n> > On Mar 11, 2022, at 8:48 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> >\\n> > I agree that it would have an impact on backwards compatibility to\\n> > change how WITH ADMIN works- but it would also get us more in line with\\n> > what the SQL standard says for how WITH ADMIN is supposed to work and\\n> > that seems worth the change to me.\\n>\\n> I'm fine with giving up some backwards compatibility to get some SQL\\n> standard compatibility, as long as we're clear that is what we're doing.\\n> What you say about the SQL spec isn't great, though, because too much power\\n> is vested in \\\"ADMIN\\\". I see \\\"ADMIN\\\" as at least three separate privileges\\n> together. Maybe it would be spec compliant to implement \\\"ADMIN\\\" as a\\n> synonym for a set of separate privileges?\\n\\n\\nI do think that’s reasonable … and believe I suggested it about 3 messages\\nago in this thread. ;) (step #3 I think it was? Or maybe 4).\\n\\n> On Mar 11, 2022, at 8:41 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> >\\n> > That we aren't discussing the issues with the current GRANT ... WITH\\n> > ADMIN OPTION and how we deviate from what the spec calls for when it\\n> > comes to DROP ROLE, which seems to be the largest thing that's\\n> > 'solved' with this ownership concept, is concerning to me.\\n>\\n> Sure, let's discuss that a bit more. Here is my best interpretation of\\n> your post about the spec, when applied to postgres with an eye towards not\\n> doing any more damage than necessary:\\n>\\n> > On Mar 10, 2022, at 11:58 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> >\\n> > let's look at what the spec says:\\n> >\\n> > CREATE ROLE\\n> > - Who is allowed to run CREATE ROLE is implementation-defined\\n>\\n> This should be anyone with membership in pg_create_role.\\n\\n\\nThat could be the case if we wished to go that route. I’d think in such\\ncase we’d then also remove CREATEROLE as otherwise the documentation feels\\nlike it’d be quite confusing.\\n\\n> - After creation, this is effictively run:\\n> > GRANT new_role TO creator_role WITH ADMIN, GRANTOR \\\"_SYSTEM\\\"\\n>\\n> This should internally be implemented as three separate privileges, one\\n> which means you can grant the role, another which means you can drop the\\n> role, and a third that means you're a member of the role. That way, they\\n> can be independently granted and revoked. We could make \\\"WITH ADMIN\\\" a\\n> short-hand for \\\"WITH G, D, M\\\" where G, D, and M are whatever we name the\\n> independent privileges Grant, Drop, and Member-of.\\n\\n\\nI mean, sure, we can get there, and possibly add more like if you’re\\nallowed to change or reset that role’s password and other things, but I\\ndon’t see that this piece is required as part of the very first change in\\nthis area. Further, WITH ADMIN already gives grant and member today, so\\nyou’re saying the only thing this change does that makes “WITH ADMIN” too\\npowerful is adding DROP to it, yet that’s explicitly what the spec calls\\nfor. In short, I disagree that moving the DROP ROLE right from CREATEROLE\\nroles having that across the entire system (excluding superusers) to WITH\\nADMIN where the role who has that right can:\\n\\nA) already become that role and drop all their objects\\nB) already GRANT that role to some other role\\n\\nis a big issue.\\n\\nSplitting G and D helps with backwards compatibility, because it gives\\n> people who want the traditional postgres \\\"admin\\\" a way to get there, by\\n> granting \\\"G+M\\\". Splitting M from G and D makes it simpler to implement the\\n> \\\"bot\\\" idea, since the bot shouldn't have M. But it does raise a question\\n> about always granting G+D+M to the creator, since the bot is the creator\\n> and we don't want the bot to have M. This isn't a problem I've invented\\n> from thin air, mind you, as G+D+M is just the definition of ADMIN per the\\n> SQL spec, if I've understood you correctly. So we need to think a bit more\\n> about the pg_create_role built-in role and whether that needs to be further\\n> refined to distinguish those who can get membership in roles they create\\n> vs. those who cannot. This line of reasoning takes me in the direction of\\n> what I think you were calling #5 upthread, but you'd have to elaborate on\\n> that, and how it interacts with the spec, for us to have a useful\\n> conversation about it.\\n\\n\\nAll that said, as I said before, I’m in favor of splitting things up and so\\nif you want to do that as part of this initial work, sure. Idk that it’s\\nabsolutely required as part of this but I’m not going to complain if it’s\\nincluded either. I agree that would allow folks to get something similar\\nto what they could get today if they want.\\n\\nI agree that the split up helps with the “bot” idea, as we could at least\\nthen create a security definer function that the bot runs and which creates\\nroles that the bot then has G for but not M or D. Even better would be to\\nalso provide a way for the “bot” to be able to create roles without the\\nneed for a security definer function where it doesn’t automatically get all\\nthree, and that was indeed what I was thinking about with the template\\nidea. The general thought there being that an admin could define a template\\nalong the lines of:\\n\\nCREATE TEMPLATE employee_template\\nCREATOR WITH ADMIN, NOMEMBERSHIP\\nROLE IN employee;\\n\\nAnd then provide a way for the bot to be given the right to use this\\ntemplate. Thinking on it a bit further, I’m guessing that we wouldn’t\\nactually give the bot pg_create_role in this case and instead would leave\\nthat to mean “able to create arbitrary roles and have all privs in that”\\nsimilar to what we are talking about where ADMIN implies the full set of\\nrights.\\n\\n> DROP ROLE\\n> > - Any user who has been GRANT'd a role with ADMIN option is able to\\n> > DROP that role.\\n>\\n> Change this to \\\"Any role who has D on the role\\\". That's spec compliant,\\n> because anyone granted ADMIN necessarily has D.\\n\\n\\nYeah.\\n\\n> GRANT ROLE\\n> > - No cycles allowed\\n> > - A role must have ADMIN rights on the role to be able to GRANT it to\\n> > another role.\\n>\\n> Change this to \\\"Any role who has G on the role\\\". That's spec compliant,\\n> because anyone grant ADMIN necessarily has G.\\n\\n\\nSure.\\n\\nWe should also fix the CREATE ROLE command to require the grantor have G on\\n> a role in order to give it to the new role as part of the command.\\n\\n\\n… or just get rid of it, which seems saner to me.\\n\\nChanging the CREATEROLE, CREATEDB, REPLICATION, and BYPASSRLS attributes\\n> into pg_create_role, pg_create_db, pg_replication, and pg_bypassrls, the\\n> creator could only give them to the created role if the creator has G on\\n> the roles. If we do this, we could keep the historical privilege bits and\\n> their syntax support for backward compatibility, or we could rip them out,\\n> but the decision between those two options is independent of the rest of\\n> the design.\\n\\n\\nYeah, turning those into predefined roles which an admin can then decide to\\ngive out (and to allow ADMIN on them to be given to folks who could then\\npass that along if they wanted) is another thought I’ve had though one\\nthat’s somewhat independent of the rest of this, but also shows how we\\ncould make those be things that a superuser could choose to give out, or\\nnot, to some set of roles who would then be able to create roles of their\\nown with those privileges.\\n\\nOn the whole, using predefined roles as the source of certain capabilities,\\nand the options discussed here which would allow an admin to grant those\\ncapabilities out with or without the ability to grant them further, plus\\nthe splitting out of the individual role-relationship rights (membership,\\ngrantable, drop, etc) strikes me as being quite flexible and extendable and\\ngenerally in the direction that we’ve been trending and which seems to be\\nreasonably successful so far.\\n\\nThanks,\\n\\nStephen\\n\\n>\\n\\nGreetings,On Fri, Mar 11, 2022 at 12:32 Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n\\n> On Mar 11, 2022, at 8:48 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> I agree that it would have an impact on backwards compatibility to\\n> change how WITH ADMIN works- but it would also get us more in line with\\n> what the SQL standard says for how WITH ADMIN is supposed to work and\\n> that seems worth the change to me.\\n\\nI'm fine with giving up some backwards compatibility to get some SQL standard compatibility, as long as we're clear that is what we're doing. What you say about the SQL spec isn't great, though, because too much power is vested in \\\"ADMIN\\\". I see \\\"ADMIN\\\" as at least three separate privileges together. Maybe it would be spec compliant to implement \\\"ADMIN\\\" as a synonym for a set of separate privileges?I do think that’s reasonable … and believe I suggested it about 3 messages ago in this thread. ;) (step #3 I think it was? Or maybe 4).\\n> On Mar 11, 2022, at 8:41 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> That we aren't discussing the issues with the current GRANT ... WITH\\n> ADMIN OPTION and how we deviate from what the spec calls for when it\\n> comes to DROP ROLE, which seems to be the largest thing that's\\n> 'solved' with this ownership concept, is concerning to me.\\n\\nSure, let's discuss that a bit more. Here is my best interpretation of your post about the spec, when applied to postgres with an eye towards not doing any more damage than necessary:\\n\\n> On Mar 10, 2022, at 11:58 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> let's look at what the spec says:\\n> \\n> CREATE ROLE\\n> - Who is allowed to run CREATE ROLE is implementation-defined\\n\\nThis should be anyone with membership in pg_create_role.That could be the case if we wished to go that route. I’d think in such case we’d then also remove CREATEROLE as otherwise the documentation feels like it’d be quite confusing.\\n> - After creation, this is effictively run:\\n> GRANT new_role TO creator_role WITH ADMIN, GRANTOR \\\"_SYSTEM\\\"\\n\\nThis should internally be implemented as three separate privileges, one which means you can grant the role, another which means you can drop the role, and a third that means you're a member of the role. That way, they can be independently granted and revoked. We could make \\\"WITH ADMIN\\\" a short-hand for \\\"WITH G, D, M\\\" where G, D, and M are whatever we name the independent privileges Grant, Drop, and Member-of.I mean, sure, we can get there, and possibly add more like if you’re allowed to change or reset that role’s password and other things, but I don’t see that this piece is required as part of the very first change in this area. Further, WITH ADMIN already gives grant and member today, so you’re saying the only thing this change does that makes “WITH ADMIN” too powerful is adding DROP to it, yet that’s explicitly what the spec calls for. In short, I disagree that moving the DROP ROLE right from CREATEROLE roles having that across the entire system (excluding superusers) to WITH ADMIN where the role who has that right can:A) already become that role and drop all their objectsB) already GRANT that role to some other roleis a big issue.\\nSplitting G and D helps with backwards compatibility, because it gives people who want the traditional postgres \\\"admin\\\" a way to get there, by granting \\\"G+M\\\". Splitting M from G and D makes it simpler to implement the \\\"bot\\\" idea, since the bot shouldn't have M. But it does raise a question about always granting G+D+M to the creator, since the bot is the creator and we don't want the bot to have M. This isn't a problem I've invented from thin air, mind you, as G+D+M is just the definition of ADMIN per the SQL spec, if I've understood you correctly. So we need to think a bit more about the pg_create_role built-in role and whether that needs to be further refined to distinguish those who can get membership in roles they create vs. those who cannot. This line of reasoning takes me in the direction of what I think you were calling #5 upthread, but you'd have to elaborate on that, and how it interacts with the spec, for us to have a useful conversation about it.All that said, as I said before, I’m in favor of splitting things up and so if you want to do that as part of this initial work, sure. Idk that it’s absolutely required as part of this but I’m not going to complain if it’s included either. I agree that would allow folks to get something similar to what they could get today if they want.I agree that the split up helps with the “bot” idea, as we could at least then create a security definer function that the bot runs and which creates roles that the bot then has G for but not M or D. Even better would be to also provide a way for the “bot” to be able to create roles without the need for a security definer function where it doesn’t automatically get all three, and that was indeed what I was thinking about with the template idea. The general thought there being that an admin could define a template along the lines of:CREATE TEMPLATE employee_templateCREATOR WITH ADMIN, NOMEMBERSHIPROLE IN employee;And then provide a way for the bot to be given the right to use this template. Thinking on it a bit further, I’m guessing that we wouldn’t actually give the bot pg_create_role in this case and instead would leave that to mean “able to create arbitrary roles and have all privs in that” similar to what we are talking about where ADMIN implies the full set of rights.\\n> DROP ROLE\\n> - Any user who has been GRANT'd a role with ADMIN option is able to\\n> DROP that role.\\n\\nChange this to \\\"Any role who has D on the role\\\". That's spec compliant, because anyone granted ADMIN necessarily has D.Yeah.\\n> GRANT ROLE\\n> - No cycles allowed\\n> - A role must have ADMIN rights on the role to be able to GRANT it to\\n> another role.\\n\\nChange this to \\\"Any role who has G on the role\\\". That's spec compliant, because anyone grant ADMIN necessarily has G.Sure.\\nWe should also fix the CREATE ROLE command to require the grantor have G on a role in order to give it to the new role as part of the command. … or just get rid of it, which seems saner to me. Changing the CREATEROLE, CREATEDB, REPLICATION, and BYPASSRLS attributes into pg_create_role, pg_create_db, pg_replication, and pg_bypassrls, the creator could only give them to the created role if the creator has G on the roles. If we do this, we could keep the historical privilege bits and their syntax support for backward compatibility, or we could rip them out, but the decision between those two options is independent of the rest of the design.Yeah, turning those into predefined roles which an admin can then decide to give out (and to allow ADMIN on them to be given to folks who could then pass that along if they wanted) is another thought I’ve had though one that’s somewhat independent of the rest of this, but also shows how we could make those be things that a superuser could choose to give out, or not, to some set of roles who would then be able to create roles of their own with those privileges.On the whole, using predefined roles as the source of certain capabilities, and the options discussed here which would allow an admin to grant those capabilities out with or without the ability to grant them further, plus the splitting out of the individual role-relationship rights (membership, grantable, drop, etc) strikes me as being quite flexible and extendable and generally in the direction that we’ve been trending and which seems to be reasonably successful so far.Thanks,Stephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 17:46:59 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 11, 2022, at 2:46 PM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> I do think that’s reasonable … and believe I suggested it about 3 messages ago in this thread. ;) (step #3 I think it was? Or maybe 4).\\n\\nYes, and you mentioned it to me off-list.\\n\\nI'm soliciting a more concrete specification for what you are proposing. To me, that means understanding how the SQL spec behavior that you champion translates into specific changes. You specified some of this in steps #1 through #5, but I'd like a clearer indication of how many of those (#1 alone, both #1 and #2, or what?) constitute a competing idea to the idea of role ownership, and greater detail about how each of those steps translate into specific behavior changes in postgres. Your initial five-step email seems to be claiming that #1 by itself is competitive, but to me it seems at least #1 and #2 would be required.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 16:03:06 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\nOn Fri, Mar 11, 2022 at 19:03 Mark Dilger <mark.dilger@enterprisedb.com>\\nwrote:\\n\\n> > On Mar 11, 2022, at 2:46 PM, Stephen Frost <sfrost@snowman.net> wrote:\\n> >\\n> > I do think that’s reasonable … and believe I suggested it about 3\\n> messages ago in this thread. ;) (step #3 I think it was? Or maybe 4).\\n>\\n> Yes, and you mentioned it to me off-list.\\n\\n\\nIndeed.\\n\\nI'm soliciting a more concrete specification for what you are proposing.\\n> To me, that means understanding how the SQL spec behavior that you champion\\n> translates into specific changes. You specified some of this in steps #1\\n> through #5, but I'd like a clearer indication of how many of those (#1\\n> alone, both #1 and #2, or what?) constitute a competing idea to the idea of\\n> role ownership, and greater detail about how each of those steps translate\\n> into specific behavior changes in postgres. Your initial five-step email\\n> seems to be claiming that #1 by itself is competitive, but to me it seems\\n> at least #1 and #2 would be required.\\n\\n\\nFirst … I outlined a fair bit of further description in the message you\\njust responded to but neglected to include in your response, which strikes\\nme as odd that you’re now asking for further explanation. When it comes to\\ncompleting the idea of role ownership- I didn’t come up with that idea nor\\nchampion it and therefore I’m not really sure how many of the steps are\\nrequired to fully support that concept..? For my part, I would think that\\nthose steps necessary to satisfy the spec would get us pretty darn close to\\nwhat true folks advocating for role ownership are asking for, but that\\ndoesn’t include the superuser-only alter role attributes piece. Is that\\nincluded in role ownership? I wouldn’t think so, but some might argue\\notherwise, and I don’t know that it is actually useful to divert into a\\ndiscussion about what is or isn’t in that.\\n\\nIf we agree that the role attribute bits are independent then I think I\\nagree that we need 1 and 2 to get the capabilities that the folks asking\\nfor role ownership want, as 2 is where we make sure that one admin of a\\nrole can’t revoke another admin’s rights over that role. Perhaps 2 isn’t\\nstrictly necessary in a carefully managed environment where no one else is\\ngiven admin rights over the mini-superuser roles, but I’d rather not have\\nfolks depending on that. I’d still push back though and ask those\\nadvocating for this if it meets what they’re asking for. I got the\\nimpression that it did but maybe I misunderstood.\\n\\nIn terms of exactly how things would work with these changes… I thought I\\nexplained it pretty clearly, so it’s kind of hard to answer that further\\nwithout a specific question to answer. Did you have something specific in\\nmind? Perhaps I could answer a specific question and provide more clarity\\nthat way.\\n\\nThanks,\\n\\nStephen\\n\\n>\\n\\nGreetings,On Fri, Mar 11, 2022 at 19:03 Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> On Mar 11, 2022, at 2:46 PM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> I do think that’s reasonable … and believe I suggested it about 3 messages ago in this thread. ;) (step #3 I think it was? Or maybe 4).\\n\\nYes, and you mentioned it to me off-list.Indeed.\\nI'm soliciting a more concrete specification for what you are proposing. To me, that means understanding how the SQL spec behavior that you champion translates into specific changes. You specified some of this in steps #1 through #5, but I'd like a clearer indication of how many of those (#1 alone, both #1 and #2, or what?) constitute a competing idea to the idea of role ownership, and greater detail about how each of those steps translate into specific behavior changes in postgres. Your initial five-step email seems to be claiming that #1 by itself is competitive, but to me it seems at least #1 and #2 would be required.First … I outlined a fair bit of further description in the message you just responded to but neglected to include in your response, which strikes me as odd that you’re now asking for further explanation. When it comes to completing the idea of role ownership- I didn’t come up with that idea nor champion it and therefore I’m not really sure how many of the steps are required to fully support that concept..? For my part, I would think that those steps necessary to satisfy the spec would get us pretty darn close to what true folks advocating for role ownership are asking for, but that doesn’t include the superuser-only alter role attributes piece. Is that included in role ownership? I wouldn’t think so, but some might argue otherwise, and I don’t know that it is actually useful to divert into a discussion about what is or isn’t in that.If we agree that the role attribute bits are independent then I think I agree that we need 1 and 2 to get the capabilities that the folks asking for role ownership want, as 2 is where we make sure that one admin of a role can’t revoke another admin’s rights over that role. Perhaps 2 isn’t strictly necessary in a carefully managed environment where no one else is given admin rights over the mini-superuser roles, but I’d rather not have folks depending on that. I’d still push back though and ask those advocating for this if it meets what they’re asking for. I got the impression that it did but maybe I misunderstood.In terms of exactly how things would work with these changes… I thought I explained it pretty clearly, so it’s kind of hard to answer that further without a specific question to answer. Did you have something specific in mind? Perhaps I could answer a specific question and provide more clarity that way.Thanks,Stephen\",\n \"msg_date\": \"Fri, 11 Mar 2022 19:56:19 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 11, 2022, at 4:56 PM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> First … I outlined a fair bit of further description in the message you just responded to but neglected to include in your response, which strikes me as odd that you’re now asking for further explanation.\\n\\n\\n\\n> When it comes to completing the idea of role ownership- I didn’t come up with that idea nor champion it\\n\\nSorry, not \\\"completing\\\", but \\\"competing\\\". It seems we're discussing different ways to fix how roles and CREATEROLE work, and we have several ideas competing against each other. (This differs from *people* competing against each other, as I don't necessarily like the patch I wrote better than I like your idea.)\\n\\n> and therefore I’m not really sure how many of the steps are required to fully support that concept..?\\n\\nThere are problems that the ownership concepts solve. I strongly suspect that your proposal could also solve those same problems, and just trying to identify the specific portions of your proposal necessary to do so.\\n\\n> For my part, I would think that those steps necessary to satisfy the spec would get us pretty darn close to what true folks advocating for role ownership are asking for\\n\\nI have little idea what \\\"true folks\\\" means in this context. As for \\\"advocating for role ownership\\\", I'm not in that group. Whether role ownership or something else, I just want some solution to a set of problems, mostly to do with needing superuser to do role management tasks.\\n\\n> , but that doesn’t include the superuser-only alter role attributes piece. Is that included in role ownership? I wouldn’t think so, but some might argue otherwise, and I don’t know that it is actually useful to divert into a discussion about what is or isn’t in that.\\n\\nIntroducing the idea of role ownership doesn't fix that. But a patch which introduces role ownership is useless unless CREATEROLE is also fixed. There isn't any point having non-superusers create and own roles if, to do so, they need a privilege which can break into superuser. But that argument is no different with a patch along the lines of what you are proposing. CREATEROLE needs fixing either way.\\n\\n> If we agree that the role attribute bits are independent\\n\\nYes.\\n\\n> then I think I agree that we need 1 and 2 to get the capabilities that the folks asking for role ownership want\\n\\nYes.\\n\\n> as 2 is where we make sure that one admin of a role can’t revoke another admin’s rights over that role.\\n\\nExactly, so #2 is part of the competing proposal. (I get the sense you might not see these as competing proposals, but I find that framing useful for deciding which approach to pursue.)\\n\\n> Perhaps 2 isn’t strictly necessary in a carefully managed environment where no one else is given admin rights over the mini-superuser roles, but I’d rather not have folks depending on that.\\n\\nI think it is necessary, and for the reason you say.\\n\\n> I’d still push back though and ask those advocating for this if it meets what they’re asking for. I got the impression that it did but maybe I misunderstood.\\n> \\n> In terms of exactly how things would work with these changes… I thought I explained it pretty clearly, so it’s kind of hard to answer that further without a specific question to answer. Did you have something specific in mind? Perhaps I could answer a specific question and provide more clarity that way.\\n\\nYour emails contained a lot of \\\"we could do this or that depending on what people want, and maybe this other thing, but that isn't really necessary, and ....\\\" which left me unclear on the proposal. I don't mean to disparage your communication style; it's just that when trying to distill technical details, high level conversation can be hard to grok.\\n\\nI have the sense that you aren't going to submit a patch, so I wanted this thread to contain enough detail for somebody else to do so. Thanks.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 11 Mar 2022 18:08:36 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Mark Dilger (mark.dilger@enterprisedb.com) wrote:\\n> > On Mar 11, 2022, at 4:56 PM, Stephen Frost <sfrost@snowman.net> wrote:\\n> > First … I outlined a fair bit of further description in the message you just responded to but neglected to include in your response, which strikes me as odd that you’re now asking for further explanation.\\n> \\n> > When it comes to completing the idea of role ownership- I didn’t come up with that idea nor champion it\\n> \\n> Sorry, not \\\"completing\\\", but \\\"competing\\\". It seems we're discussing different ways to fix how roles and CREATEROLE work, and we have several ideas competing against each other. (This differs from *people* competing against each other, as I don't necessarily like the patch I wrote better than I like your idea.)\\n> \\n> > and therefore I’m not really sure how many of the steps are required to fully support that concept..?\\n> \\n> There are problems that the ownership concepts solve. I strongly suspect that your proposal could also solve those same problems, and just trying to identify the specific portions of your proposal necessary to do so.\\n\\nI'm happy to help try to identify those, but it seems we'd need to have\\nthe exact problems that ownership solves defined first. Robert defined\\nwhat he's looking for as:\\n\\nRobert Haas <robertmhaas@gmail.com> wrote:\\n> Probably easier to just say it again: I want to have users that can\\n> create roles and then have superuser-like powers with respect to those\\n> roles. They can freely exercise the privileges of those roles, and\\n> they can do all the things that a superuser can do but only with\\n> respect to those roles. They cannot break out to the OS. I think it's\\n> pretty similar to what you are describing, with a couple of possible\\n> exceptions. For example, would you imagine that being an admin of a\\n> login role would let you change that user's password? Because that\\n> would be desirable behavior from where I sit.\\n\\nWhich sure sounds like it's just about covered in step #1 of what I\\noutlined before, except that the above description implies that one\\ncan't \\\"get away\\\" from the user who created their role, in which case we\\ndo need step #2 also.\\n\\n> > For my part, I would think that those steps necessary to satisfy the spec would get us pretty darn close to what true folks advocating for role ownership are asking for\\n> \\n> I have little idea what \\\"true folks\\\" means in this context. As for \\\"advocating for role ownership\\\", I'm not in that group. Whether role ownership or something else, I just want some solution to a set of problems, mostly to do with needing superuser to do role management tasks.\\n\\n... I'm not entirely sure what I meant there either, my hunch is that\\n'true' was actually just a leftover word from some other framing of that\\nsentence and I had meant to remove it. Apologies for that. What I was\\ntrying to get at there is that steps #1 & #2 are the ones that I view as\\ngetting us closer to spec compliance and that doing so would get us to\\nwhere Robert's ask above would be answered.\\n\\n> > , but that doesn’t include the superuser-only alter role attributes piece. Is that included in role ownership? I wouldn’t think so, but some might argue otherwise, and I don’t know that it is actually useful to divert into a discussion about what is or isn’t in that.\\n> \\n> Introducing the idea of role ownership doesn't fix that. But a patch which introduces role ownership is useless unless CREATEROLE is also fixed. There isn't any point having non-superusers create and own roles if, to do so, they need a privilege which can break into superuser. But that argument is no different with a patch along the lines of what you are proposing. CREATEROLE needs fixing either way.\\n\\nThere's a few ways to have the 'CREATEROLE' role attribute be fixed-\\n\\n- Remove it entirely (replacing with pg_create_role or such)\\n- Remove its ability to GRANT out rights that the role running it\\n doesn't have\\n- Make it superfluous (leave it as-is, but add in pg_create_role which\\n allows a role to create another role but doesn't include the magic\\n GRANT whatever-role TO whatever-role that CREATEROLE has)\\n\\nI agree that we need to do something here to allow roles to create other\\nroles while not having or being able to trivially get superuser\\nthemselves.\\n\\n> > If we agree that the role attribute bits are independent\\n> \\n> Yes.\\n\\nGreat.\\n\\n> > then I think I agree that we need 1 and 2 to get the capabilities that the folks asking for role ownership want\\n> \\n> Yes.\\n\\nOk.\\n\\n> > as 2 is where we make sure that one admin of a role can’t revoke another admin’s rights over that role.\\n> \\n> Exactly, so #2 is part of the competing proposal. (I get the sense you might not see these as competing proposals, but I find that framing useful for deciding which approach to pursue.)\\n\\n... and is also part of getting us closer to the spec.\\n\\n> > Perhaps 2 isn’t strictly necessary in a carefully managed environment where no one else is given admin rights over the mini-superuser roles, but I’d rather not have folks depending on that.\\n> \\n> I think it is necessary, and for the reason you say.\\n\\nGreat.\\n\\n> > I’d still push back though and ask those advocating for this if it meets what they’re asking for. I got the impression that it did but maybe I misunderstood.\\n> > \\n> > In terms of exactly how things would work with these changes… I thought I explained it pretty clearly, so it’s kind of hard to answer that further without a specific question to answer. Did you have something specific in mind? Perhaps I could answer a specific question and provide more clarity that way.\\n> \\n> Your emails contained a lot of \\\"we could do this or that depending on what people want, and maybe this other thing, but that isn't really necessary, and ....\\\" which left me unclear on the proposal. I don't mean to disparage your communication style; it's just that when trying to distill technical details, high level conversation can be hard to grok.\\n\\nFeel free to quote me explicitly in such places that you're looking for\\nclarification and I'd be happy to drill down on those.\\n\\n> I have the sense that you aren't going to submit a patch, so I wanted this thread to contain enough detail for somebody else to do so. Thanks.\\n\\nSo ... do you feel like that's now the case? Or were you looking for\\nmore?\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 14 Mar 2022 10:38:10 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Mar 14, 2022, at 7:38 AM, Stephen Frost <sfrost@snowman.net> wrote:\\n> \\n> So ... do you feel like that's now the case? Or were you looking for\\n> more?\\n\\nI don't have any more questions at the moment. Thanks!\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 14 Mar 2022 08:45:14 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 11, 2022 at 11:51 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Fri, Mar 11, 2022 at 11:34 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > Note that either case would also involve making entries in pg_shdepend;\\n> > although for the case of roles owned by/granted to the bootstrap\\n> > superuser, we could omit those on the usual grounds that we don't need\\n> > to record dependencies on pinned objects.\\n>\\n> That makes sense to me, but it still doesn't solve the problem of\\n> agreeing on role ownership vs. WITH ADMIN OPTION vs. something else.\\n\\nNotwithstanding the lack of agreement on that point, I believe that\\nwhat we should do for v15 is remove the session user\\nself-administration exception. We have pretty much established that it\\nwas originally introduced in error. It later was found to be a\\nsecurity vulnerability, and that resulted in the exception being\\nnarrowed without removing it altogether. While there are differences\\nof opinion on what the larger plan here ought to be, nobody's proposal\\nplan involves retaining that exception. Neither has anyone offered a\\nplausible use case for the current behavior, so there's no reason to\\nthink that removing it would break anything.\\n\\nHowever, it might. And if it does, I think it would be best if\\nremoving that exception were the *only* change in this area made by\\nthat release. If for v16 or v17 or v23 we implement Plan Tom or Plan\\nStephen or Plan Robert or something else, and along the way we remove\\nthat self-administration exception, we're going to have a real fire\\ndrill if it turns out that the self-administration exception was\\nimportant for some reason we're not seeing right now. If, on the other\\nhand, we remove that exception in v15, then if anything breaks, it'll\\nbe a lot easier to deal with. Worst case scenario we just revert the\\nremoval of that exception, which will be a very localized change if\\nnothing else has been done that depends heavily on its having been\\nremoved.\\n\\nSo I propose to commit something like what I posted here:\\n\\nhttp://postgr.es/m/CA+TgmobgeK0JraOwQVPqhSXcfBdFitXSomoebHMMMhmJ4gLonw@mail.gmail.com\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 12:46:43 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> Notwithstanding the lack of agreement on that point, I believe that\\n> what we should do for v15 is remove the session user\\n> self-administration exception. We have pretty much established that it\\n> was originally introduced in error.\\n\\nAgreed.\\n\\n> However, it might. And if it does, I think it would be best if\\n> removing that exception were the *only* change in this area made by\\n> that release.\\n\\nGood idea, especially since it's getting to be too late to consider\\nanything more invasive anyway.\\n\\n> So I propose to commit something like what I posted here:\\n> http://postgr.es/m/CA+TgmobgeK0JraOwQVPqhSXcfBdFitXSomoebHMMMhmJ4gLonw@mail.gmail.com\\n\\n+1, although the comments might need some more work. In particular,\\nI'm not sure that this bit is well stated:\\n\\n+\\t * A role cannot have WITH ADMIN OPTION on itself, because that would\\n+\\t * imply a membership loop.\\n\\nWe already do consider a role to be a member of itself:\\n\\nregression=# create role r;\\nCREATE ROLE\\nregression=# grant r to r;\\nERROR: role \\\"r\\\" is a member of role \\\"r\\\"\\nregression=# grant r to r with admin option;\\nERROR: role \\\"r\\\" is a member of role \\\"r\\\"\\n\\nIt might be better to just say \\\"By policy, a role cannot have WITH ADMIN\\nOPTION on itself\\\". But if you want to write a defense of that policy,\\nthis isn't a very good one.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 13:10:26 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 24, 2022 at 1:10 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > However, it might. And if it does, I think it would be best if\\n> > removing that exception were the *only* change in this area made by\\n> > that release.\\n>\\n> Good idea, especially since it's getting to be too late to consider\\n> anything more invasive anyway.\\n\\nI'd say it's definitely too late at this point.\\n\\n> > So I propose to commit something like what I posted here:\\n> > http://postgr.es/m/CA+TgmobgeK0JraOwQVPqhSXcfBdFitXSomoebHMMMhmJ4gLonw@mail.gmail.com\\n>\\n> +1, although the comments might need some more work. In particular,\\n> I'm not sure that this bit is well stated:\\n>\\n> + * A role cannot have WITH ADMIN OPTION on itself, because that would\\n> + * imply a membership loop.\\n>\\n> We already do consider a role to be a member of itself:\\n>\\n> regression=# create role r;\\n> CREATE ROLE\\n> regression=# grant r to r;\\n> ERROR: role \\\"r\\\" is a member of role \\\"r\\\"\\n> regression=# grant r to r with admin option;\\n> ERROR: role \\\"r\\\" is a member of role \\\"r\\\"\\n>\\n> It might be better to just say \\\"By policy, a role cannot have WITH ADMIN\\n> OPTION on itself\\\". But if you want to write a defense of that policy,\\n> this isn't a very good one.\\n\\nThat sentence is present in the current code, along with a bunch of\\nother sentences, which the patch renders irrelevant. So I just deleted\\nall of the other stuff and kept the sentence that is still relevant to\\nthe revised code. I think your proposed replacement is an improvement,\\nbut let's be careful not to get sucked into too much of a wordsmithing\\nexercise in a patch that's here to make a functional change.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 13:26:48 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Thu, Mar 24, 2022 at 1:10 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > > However, it might. And if it does, I think it would be best if\\n> > > removing that exception were the *only* change in this area made by\\n> > > that release.\\n> >\\n> > Good idea, especially since it's getting to be too late to consider\\n> > anything more invasive anyway.\\n> \\n> I'd say it's definitely too late at this point.\\n\\nAgreed.\\n\\n> > > So I propose to commit something like what I posted here:\\n> > > http://postgr.es/m/CA+TgmobgeK0JraOwQVPqhSXcfBdFitXSomoebHMMMhmJ4gLonw@mail.gmail.com\\n> >\\n> > +1, although the comments might need some more work. In particular,\\n> > I'm not sure that this bit is well stated:\\n\\nAlso +1 on this.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 28 Mar 2022 10:51:37 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 28, 2022 at 10:51 AM Stephen Frost <sfrost@snowman.net> wrote:\\n> > > > So I propose to commit something like what I posted here:\\n> > > > http://postgr.es/m/CA+TgmobgeK0JraOwQVPqhSXcfBdFitXSomoebHMMMhmJ4gLonw@mail.gmail.com\\n> > >\\n> > > +1, although the comments might need some more work. In particular,\\n> > > I'm not sure that this bit is well stated:\\n>\\n> Also +1 on this.\\n\\nOK, done using Tom's proposed wording.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 14:31:04 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: role self-revocation\"\n },\n {\n \"msg_contents\": \"The cfbot is testing the last patch posted to this thread which is the\\nremove-self-own patch which was already committed. I gather that\\nthere's still (at least one) patch under discussion.\\n\\nCould I suggest reposting the last version of the main patch, perhaps\\nrebasing it. That way the cfbot would at least continue to test for\\nconflicts.\\n\\n\\n\",\n \"msg_date\": \"Fri, 1 Apr 2022 10:46:07 -0400\",\n \"msg_from\": \"Greg Stark <stark@mit.edu>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: CREATEROLE and role ownership hierarchies\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 1, 2022 at 10:46 AM Greg Stark <stark@mit.edu> wrote:\\n> The cfbot is testing the last patch posted to this thread which is the\\n> remove-self-own patch which was already committed. I gather that\\n> there's still (at least one) patch under discussion.\\n>\\n> Could I suggest reposting the last version of the main patch, perhaps\\n> rebasing it. That way the cfbot would at least continue to test for\\n> conflicts.\\n\\nWe should move this patch to the next CF or maybe even mark it\\nreturned with feedback. We're not going to get anything else done here\\nfor v15, and I'm not sure whether what we do beyond that will take\\nthis form or not.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 1 Apr 2022 10:56:35 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: CREATEROLE and role ownership hierarchies\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 4, 2022 at 4:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> If we are not tracking the grantors of role authorizations,\\n> then we are doing it wrong and we ought to fix that.\\n\\nWe are definitely doing it wrong. It's not that we aren't doing it at\\nall, but we are doing it incorrectly. If user foo executes \\\"GRANT foo\\nTO bar GRANTED BY quux\\\", pg_auth_members.grantor gets the OID of role\\n\\\"quux\\\". Without the \\\"GRANTED BY\\\" clause, it gets the OID of role\\n\\\"foo\\\". But no dependency is created; therefore, the OID of that column\\ncan point to a role that no longer exists, or potentially to a role\\nthat did exist at one point, was dropped, and was later replaced by\\nsome other role that happens to get the same OID. pg_dump handles this\\nby dumping \\\"GRANTED BY whoever\\\" if pg_auth_members.grantor is a\\nstill-extant role and omitting the clause if not. This would be a\\nsecurity vulnerability if there were any logic in the backend that\\nactually did anything with pg_auth_members.grantor, because if the\\noriginal grantor is removed and replaced by another role with the same\\nOID, a dump/restore could change the notional grantor. Since there is\\nno such logic, I don't think it's insecure, but it's still really\\nlame.\\n\\nSo let's talk about how we could fix this. In a vacuum I'd say this is\\njust a feature that never got finished and we should rip the whole\\nthing out. That is, remove pg_auth_members.grantor entirely and at\\nmost keep some do-nothing syntax around for backward compatibility.\\nHowever, what Tom is saying in the text quoted above is that we ought\\nto have something that actually works, which is more challenging.\\nApparently, the desired behavior here is for this to work like grants\\non non-role objects, where executing \\\"GRANT SELECT ON TABLE s1 TO foo\\\"\\nunder two different user accounts bar and baz that both have\\npermissions to grant that privilege creates two independent grants\\nthat can be independently revoked. To get there, we'll have to change\\na good few things -- not only will we need a dependency to prevent a\\ngrantor from being dropped without revoking the grant, but we need to\\nchange the primary key of pg_auth_members from (roleid, member) to\\n(roleid, member, grantor). Then we'll also have to change the behavior\\nof the GRANT and REVOKE commands at the SQL level, and also the\\nbehavior of pg_dump, which will need to dump and restore all grants.\\n\\nI'm open to other proposals, but my thought is that it might be\\nsimplest to try to clean this up in two steps. In step one, the only\\ngoal would be to make pg_auth_members.grantor reliably sane. In other\\nwords, we'd add a dependency on the grantor when a role is granted to\\nanother role. You could still only have one grant of role A to role B,\\nbut the notional grantor C would always be a user that actually\\nexists. I suspect it would be a really good idea to also patch pg_dump\\nto not ever dump the grantor when working from an older release,\\nbecause the information is not necessarily reliable and I fear that\\npropagating it forward could lead to broken stuff or maybe even\\nsecurity hazards as noted above. Then, in step two, we change things\\naround to allow multiple grants of the same role to the same other\\nrole, one per grantor. Now you've achieved parity between the behavior\\nwe have for roles and the behavior we have for permissions on other\\nkinds of SQL objects.\\n\\nThere may be other improvements we want to make in this area -\\nprevious discussions have suggested various ideas - but it seems to me\\nthat making the behavior sane and consistent with other types of\\nobjects would be a good start. That way, if we decide we do want to\\nchange anything else, we will be starting from a firm foundation,\\nrather than building on sand.\\n\\nThoughts?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Jun 2022 14:31:24 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Fri, Mar 4, 2022 at 4:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> If we are not tracking the grantors of role authorizations,\\n>> then we are doing it wrong and we ought to fix that.\\n\\n> So let's talk about how we could fix this. In a vacuum I'd say this is\\n> just a feature that never got finished and we should rip the whole\\n> thing out. That is, remove pg_auth_members.grantor entirely and at\\n> most keep some do-nothing syntax around for backward compatibility.\\n> However, what Tom is saying in the text quoted above is that we ought\\n> to have something that actually works, which is more challenging.\\n> Apparently, the desired behavior here is for this to work like grants\\n> on non-role objects, where executing \\\"GRANT SELECT ON TABLE s1 TO foo\\\"\\n> under two different user accounts bar and baz that both have\\n> permissions to grant that privilege creates two independent grants\\n> that can be independently revoked.\\n\\nMaybe. What I was pointing out is that this is SQL-standard syntax\\nand there are SQL-standard semantics that it ought to be implementing.\\nProbably those semantics match what you describe here, but we ought\\nto dive into the spec and make sure before we spend a lot of effort.\\nIt's not quite clear to me whether the spec defines any particular\\nunique key (identity) for the set of role authorizations.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 02 Jun 2022 15:15:13 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Thu, Jun 2, 2022 at 3:15 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Maybe. What I was pointing out is that this is SQL-standard syntax\\n> and there are SQL-standard semantics that it ought to be implementing.\\n> Probably those semantics match what you describe here, but we ought\\n> to dive into the spec and make sure before we spend a lot of effort.\\n> It's not quite clear to me whether the spec defines any particular\\n> unique key (identity) for the set of role authorizations.\\n\\nI sort of thought http://postgr.es/m/3981966.1646429663@sss.pgh.pa.us\\nconstituted a completed investigation of this sort. No?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Jun 2022 15:40:37 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Thu, Jun 2, 2022 at 3:15 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Maybe. What I was pointing out is that this is SQL-standard syntax\\n>> and there are SQL-standard semantics that it ought to be implementing.\\n>> Probably those semantics match what you describe here, but we ought\\n>> to dive into the spec and make sure before we spend a lot of effort.\\n>> It's not quite clear to me whether the spec defines any particular\\n>> unique key (identity) for the set of role authorizations.\\n\\n> I sort of thought http://postgr.es/m/3981966.1646429663@sss.pgh.pa.us\\n> constituted a completed investigation of this sort. No?\\n\\nI didn't think so. It's clear that the spec expects us to track the\\ngrantor, but I didn't chase down what it expects us to *do* with that\\ninformation, nor what it thinks the rules are for merging multiple\\nauthorizations.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 02 Jun 2022 15:50:58 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Thu, Jun 2, 2022 at 3:51 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > I sort of thought http://postgr.es/m/3981966.1646429663@sss.pgh.pa.us\\n> > constituted a completed investigation of this sort. No?\\n>\\n> I didn't think so. It's clear that the spec expects us to track the\\n> grantor, but I didn't chase down what it expects us to *do* with that\\n> information, nor what it thinks the rules are for merging multiple\\n> authorizations.\\n\\nHmm, OK. Well, one problem is that I've never had any luck\\ninterpreting what the spec says about anything, and I've sort of given\\nup. But even if that were not so, I'm a little unclear what other\\nconclusion is possible here. The spec either wants the same behavior\\nthat we already have for other object types, which is what I am here\\nproposing that we do, or it wants something different. If it wants\\nsomething different, it probably wants that for all object types, not\\njust roles. Since I doubt we would want the behavior for roles to be\\ninconsistent with what we do for all other object types, in that case\\nwe would probably either change the behavior for all other object\\ntypes to something new, and then clean up the role stuff afterwards,\\nor else first do what I proposed here and then later change it all at\\nonce. In which case the proposal that I've made is as good a way to\\nstart as any.\\n\\nNow, if it happens to be the case that the spec proposes a different\\nbehavior for roles than for non-role objects, and if the behavior for\\nroles is something other than the only we currently have for non-role\\nobjects, then I'd agree that the plan I propose here needs revision. I\\nsuspect that's unlikely but I can't make anything of the spec so ....\\nmaybe?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Jun 2022 16:44:02 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Thu, Jun 2, 2022 at 3:51 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > > I sort of thought http://postgr.es/m/3981966.1646429663@sss.pgh.pa.us\\n> > > constituted a completed investigation of this sort. No?\\n> >\\n> > I didn't think so. It's clear that the spec expects us to track the\\n> > grantor, but I didn't chase down what it expects us to *do* with that\\n> > information, nor what it thinks the rules are for merging multiple\\n> > authorizations.\\n> \\n> Hmm, OK. Well, one problem is that I've never had any luck\\n> interpreting what the spec says about anything, and I've sort of given\\n> up. But even if that were not so, I'm a little unclear what other\\n> conclusion is possible here. The spec either wants the same behavior\\n> that we already have for other object types, which is what I am here\\n> proposing that we do, or it wants something different. If it wants\\n> something different, it probably wants that for all object types, not\\n> just roles. Since I doubt we would want the behavior for roles to be\\n> inconsistent with what we do for all other object types, in that case\\n> we would probably either change the behavior for all other object\\n> types to something new, and then clean up the role stuff afterwards,\\n> or else first do what I proposed here and then later change it all at\\n> once. In which case the proposal that I've made is as good a way to\\n> start as any.\\n> \\n> Now, if it happens to be the case that the spec proposes a different\\n> behavior for roles than for non-role objects, and if the behavior for\\n> roles is something other than the only we currently have for non-role\\n> objects, then I'd agree that the plan I propose here needs revision. I\\n> suspect that's unlikely but I can't make anything of the spec so ....\\n> maybe?\\n\\nThankfully, at least from my reading, the spec isn't all that\\ncomplicated on this particular point. The spec talks about \\\"role\\nauthorization descriptor\\\"s and those are \\\"created with role name,\\ngrantee, and grantor\\\" and then further says \\\"redundant duplicate role\\nauthorization descriptors are destroyed\\\", presumably meaning that the\\nentire thing has to be identical. In other words, yeah, the PK should\\ninclude the grantor. There's a further comment that the 'set of\\ninvolved grantees' is the union of all the 'grantees', clearly\\nindicating that you can have multiple GRANT 'foo' to 'bar's with\\ndistinct grantees.\\n\\nIn terms of how that's then used, yeah, it's during REVOKE because a\\nREVOKE is only able to 'find' role authorization descriptors which match\\nthe triple of role revoked, grantee, grantor (though there's a caveat in\\nthat the 'grantor' role could be the current role, or the current user).\\n\\nInterestingly, at least in my looking it over today, it doesn't seem\\nthat the 'grantor' could be 'any applicable role' (which is what's\\nusually used to indicate that it could be any role that the current role\\ninherits), meaning you have to include the GRANTED BY in the REVOKE\\nstatement or do a SET ROLE first when doing a REVOKE if it's for a role\\nthat you aren't currently running as (but which you are a member of).\\n\\nAnyhow, in other words, I do think Robert's got it right here. Happy to\\ndiscuss further though if there are doubts.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 6 Jun 2022 19:41:02 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Mon, Jun 6, 2022 at 7:41 PM Stephen Frost <sfrost@snowman.net> wrote:\\n> Thankfully, at least from my reading, the spec isn't all that\\n> complicated on this particular point. The spec talks about \\\"role\\n> authorization descriptor\\\"s and those are \\\"created with role name,\\n> grantee, and grantor\\\" and then further says \\\"redundant duplicate role\\n> authorization descriptors are destroyed\\\", presumably meaning that the\\n> entire thing has to be identical. In other words, yeah, the PK should\\n> include the grantor. There's a further comment that the 'set of\\n> involved grantees' is the union of all the 'grantees', clearly\\n> indicating that you can have multiple GRANT 'foo' to 'bar's with\\n> distinct grantees.\\n>\\n> In terms of how that's then used, yeah, it's during REVOKE because a\\n> REVOKE is only able to 'find' role authorization descriptors which match\\n> the triple of role revoked, grantee, grantor (though there's a caveat in\\n> that the 'grantor' role could be the current role, or the current user).\\n\\nWhat is supposed to happen if someone tries to execute DROP ROLE on a\\nrole that has previously been used as a grantor?\\n\\nConsider:\\n\\ncreate role foo;\\ncreate role bar;\\ncreate role baz;\\ngrant foo to bar granted by baz;\\ndrop role baz;\\n\\nUpthread, I proposed that \\\"drop role baz\\\" should fail here, but\\nthere's at least one other option: it could silently remove the grant,\\nas we would do if either foo or bar were dropped. The situation is not\\nquite comparable, though: a grant from foo to bar makes no logical\\nsense if either of those roles cease to exist, but it does make at\\nleast some sense if baz ceases to exist. Therefore I think someone\\ncould argue either for an error or for removing the grant -- or\\npossibly even for some other behavior, though the other behaviors that\\nI can think of don't make much sense in a world where the primary key\\nof pg_auth_members is (roleid, member, grantor).\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Jun 2022 16:19:34 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, Jun 24, 2022 at 1:19 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n\\n> On Mon, Jun 6, 2022 at 7:41 PM Stephen Frost <sfrost@snowman.net> wrote:\\n> >\\n> > In terms of how that's then used, yeah, it's during REVOKE because a\\n> > REVOKE is only able to 'find' role authorization descriptors which match\\n> > the triple of role revoked, grantee, grantor (though there's a caveat in\\n> > that the 'grantor' role could be the current role, or the current user).\\n>\\n> What is supposed to happen if someone tries to execute DROP ROLE on a\\n> role that has previously been used as a grantor?\\n>\\n> Upthread, I proposed that \\\"drop role baz\\\" should fail here\\n>\\n\\nI concur with this.\\n\\nI think that the grantor owns the grant, and that REASSIGNED OWNED should\\nbe able to move those grants to someone else.\\n\\nBy extension, DROP OWNED should remove them.\\n\\nDavid J.\\n\\nOn Fri, Jun 24, 2022 at 1:19 PM Robert Haas <robertmhaas@gmail.com> wrote:On Mon, Jun 6, 2022 at 7:41 PM Stephen Frost <sfrost@snowman.net> wrote:>\\n> In terms of how that's then used, yeah, it's during REVOKE because a\\n> REVOKE is only able to 'find' role authorization descriptors which match\\n> the triple of role revoked, grantee, grantor (though there's a caveat in\\n> that the 'grantor' role could be the current role, or the current user).\\n\\nWhat is supposed to happen if someone tries to execute DROP ROLE on a\\nrole that has previously been used as a grantor?\\nUpthread, I proposed that \\\"drop role baz\\\" should fail hereI concur with this.I think that the grantor owns the grant, and that REASSIGNED OWNED should be able to move those grants to someone else.By extension, DROP OWNED should remove them.David J.\",\n \"msg_date\": \"Fri, 24 Jun 2022 13:29:47 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, Jun 24, 2022 at 4:30 PM David G. Johnston\\n<david.g.johnston@gmail.com> wrote:\\n>> Upthread, I proposed that \\\"drop role baz\\\" should fail here\\n>\\n> I concur with this.\\n>\\n> I think that the grantor owns the grant, and that REASSIGNED OWNED should be able to move those grants to someone else.\\n>\\n> By extension, DROP OWNED should remove them.\\n\\nInteresting. I hadn't thought about changing the behavior of DROP\\nOWNED BY and REASSIGN OWNED BY. A quick experiment supports your\\ninterpretation:\\n\\nrhaas=# grant select on table foo to bar;\\nGRANT\\nrhaas=# revoke select on table foo from bar;\\nREVOKE\\nrhaas=# grant select on table foo to bar with grant option;\\nGRANT\\nrhaas=# set role bar;\\nSET\\nrhaas=> grant select on table foo to baz;\\nGRANT\\nrhaas=> reset role;\\nRESET\\nrhaas=# drop role bar;\\nERROR: role \\\"bar\\\" cannot be dropped because some objects depend on it\\nDETAIL: privileges for table foo\\nrhaas=# drop owned by bar;\\nDROP OWNED\\nrhaas=# drop role bar;\\nDROP ROLE\\n\\nSo, privileges on tables (and presumably all other SQL objects)\\nalready work the way that you propose here. If we choose to make role\\nmemberships work in some other way then the two will be inconsistent.\\nProbably we shouldn't do that. There is still the question of what the\\nSQL specification says about this, but I would guess that it mandates\\nthe same behavior for all kinds of privileges rather than treating\\nrole memberships and table permissions in different ways. I could be\\nwrong, though.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Jun 2022 16:46:42 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, Jun 24, 2022 at 4:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> Interesting. I hadn't thought about changing the behavior of DROP\\n> OWNED BY and REASSIGN OWNED BY. A quick experiment supports your\\n> interpretation:\\n\\nHere is a minimal patch fixing exactly $SUBJECT. Granting a role to\\nanother role now creates a dependency on the grantor, so if you try to\\ndrop the grantor you get an ERROR. You can resolve that by revoking\\nthe grant, or by using DROP OWNED BY or REASSIGN OWNED BY. To make\\nthis work, I had to make role memberships participate in the\\ndependency system, which means pg_auth_members gains an OID column.\\nThe tricky part is that removing either of the two roles directly\\ninvolved in a grant currently does, and should still, silently remove\\nthe grant. So, if you do \\\"GRANT foo TO bar GRANTED BY baz\\\", and then\\ntry to \\\"DROP ROLE baz\\\", that should fail, but if you instead try to\\n\\\"DROP ROLE baz, bar\\\", that should work, because when bar is removed,\\nthe grant is silently removed, and then it's OK to drop baz. If these\\nwere database-local objects I think this could have all been sorted\\nout quite easily by creating dependencies on all three roles involved\\nin the GRANT and using the right deptype for each, but shared objects\\nhave their own set of deptypes which seemed to present no easy\\nsolution to this problem. I resolved the issue by having DropRole()\\nmake two loops over the list of roles to be dropped rather than one;\\nsee patch for details.\\n\\nThere are several things that I think ought to be changed which this\\npatch does not change. Most likely, I'll try to write separate patches\\nfor those things rather than making this one bigger.\\n\\nFirst, as discussed upthread, I think we ought to change things so\\nthat you can have multiple simultaneous grants of role A to role B\\neach with a different grantor. That is what we do for other types of\\ngrants and Stephen at least thinks it's what the SQL standard\\nspecifies.\\n\\nSecond, I think we ought to enforce that the grantor has to be a role\\nwhich has the ability to perform the grant, just as we do for other\\nobject types. This is a little thorny, though, because we play some\\ntricks with other types of objects that don't work for roles. If\\nsuperuser alice executes \\\"GRANT SELECT ON bobs_table TO fred\\\" we\\nrecord the owner of the grant as being the table owner and update the\\nownership of the grant each time the table owner is changed. That way,\\neven if alice ceases to be a superuser, we maintain the invariant that\\nthe grantor of record must have privileges to perform the grant. But\\nif superuser alice executes \\\"GRANT accounting TO fred\\\", we can't use\\nthe same trick, because the \\\"accounting\\\" role doesn't have an owner.\\nIf we attribute the grant to alice and she ceases to be a superuser\\n(and also doesn't have CREATEROLE) then the invariant is violated.\\nAttributing the grant to the bootstrap superuser doesn't help, as that\\nuser can also be made not a superuser. Attributing the grant to\\naccounting is no good, as accounting doesn't and can't have ADMIN\\nOPTION on itself; and fred doesn't have to have ADMIN OPTION on\\naccounting either.\\n\\nOne way to fix this problem would be to prohibit the removal of\\nsuperuser privileges from the booststrap superuser. Then, we could\\nattribute grants made by users who lack ADMIN OPTION on the granted\\nrole to the bootstrap superuser. Grants made by users who do possess\\nADMIN OPTION would be attributed to the actual grantor (unless GRANTED\\nBY was used) and removing ADMIN OPTION from such a user could be made\\nto fail if they had outstanding role grants. I think that's probably\\nthe nearest analogue of what we do for other object types, but if\\nyou've got another idea what to do here, I'd love to hear it.\\n\\nThoughts on this patch would be great, too.\\n\\nThanks,\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Thu, 30 Jun 2022 11:23:19 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, Jun 24, 2022 at 4:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Fri, Jun 24, 2022 at 4:30 PM David G. Johnston\\n> <david.g.johnston@gmail.com> wrote:\\n> >> Upthread, I proposed that \\\"drop role baz\\\" should fail here\\n> >\\n> > I concur with this.\\n> >\\n> > I think that the grantor owns the grant, and that REASSIGNED OWNED should be able to move those grants to someone else.\\n> >\\n> > By extension, DROP OWNED should remove them.\\n>\\n> Interesting. I hadn't thought about changing the behavior of DROP\\n> OWNED BY and REASSIGN OWNED BY. A quick experiment supports your\\n> interpretation:\\n\\nThis experiment was insufficiently thorough. I see now that, for other\\nobject types, DROP OWNED BY does work in the way that you propose, but\\nREASSIGN OWNED BY does not. Here's a better test:\\n\\nrhaas=# create table foo();\\nCREATE TABLE\\nrhaas=# create role bar;\\nCREATE ROLE\\nrhaas=# create role baz;\\nCREATE ROLE\\nrhaas=# grant select on table foo to bar with grant option;\\nGRANT\\nrhaas=# set role bar;\\nSET\\nrhaas=> grant select on table foo to baz;\\nGRANT\\nrhaas=> reset role;\\nRESET\\nrhaas=# drop role bar;\\nERROR: role \\\"bar\\\" cannot be dropped because some objects depend on it\\nDETAIL: privileges for table foo\\nrhaas=# create role quux;\\nCREATE ROLE\\nrhaas=# reassign owned by bar to quux;\\nREASSIGN OWNED\\nrhaas=# drop role bar;\\nERROR: role \\\"bar\\\" cannot be dropped because some objects depend on it\\nDETAIL: privileges for table foo\\nrhaas=# drop owned by bar;\\nDROP OWNED\\nrhaas=# drop role bar;\\nDROP ROLE\\n\\nThis behavior might look somewhat bizarre, but there's actually a good\\nreason for it: the system guarantees that whoever is listed as the\\ngrantor of a privilege has the *current* right to grant that\\nprivilege. It can't categorically change the grantor of every\\nprivilege given by bar to quux because quux might not and in fact does\\nnot have the right to grant select on table foo to baz. Now, you might\\nbe thinking, ah, but what if the superuser performed the grant? They\\ncould cease to be the superuser later, and then the rule would be\\nviolated! But actually not, because a grant by the superuser is\\nimputed to the table owner, who always has the right to grant all\\nrights on the table, and if the table owner is ever changed, all the\\ngrants imputed to the old table owner are changed to have their\\ngrantor as the new table owner. Similarly, trying to revoke select, or\\nthe grant option on it, from bar would fail. So it looks pretty\\nintentional, and pretty tightly-enforced, that every role listed as a\\ngrantor must be one which is currently able to grant that privilege.\\n\\nAnd that means that REASSIGN OWNED can't just do a blanket change to\\nthe recorded grantor. It could try to do so, I suppose, and just throw\\nan error if it doesn't work out, but that might make REASSIGN OWNED\\nfail a lot more often, which could suck. In any event, the implemented\\nbehavior is that REASSIGN OWNED does nothing about permissions, but\\nDROP OWNED cascades to grantors. This is SORT OF documented, although\\nthe documentation only mentions that DROP OWNED cascades to privileges\\ngranted *to* the target role, and does not mention that it also\\ncascades to privileges granted *by* the target role.\\n\\nThe previous version of the patch makes both DROP OWNED and REASSIGN\\nOWNED cascade to grantors, but I now think that, for consistency, I'd\\nbetter look into changing it so that only DROP OWNED cascades. I think\\nperhaps I should be using SHARED_DEPENDENCY_ACL instead of\\nSHARED_DEPENDENCY_OWNER.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 20 Jul 2022 15:11:09 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Wed, Jul 20, 2022 at 3:11 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> The previous version of the patch makes both DROP OWNED and REASSIGN\\n> OWNED cascade to grantors, but I now think that, for consistency, I'd\\n> better look into changing it so that only DROP OWNED cascades. I think\\n> perhaps I should be using SHARED_DEPENDENCY_ACL instead of\\n> SHARED_DEPENDENCY_OWNER.\\n\\nAll right, here's a new patch set, now with a second patch added to the series.\\n\\n0001, as before, is a minimal fix for $SUBJECT, but it now uses\\nSHARED_DEPENDENCY_ACL instead of SHARED_DEPENDENCY_OWNER, because that\\ngives behavior which is more like what we do for other object types.\\nHowever, it confines itself to making sure that\\npg_auth_members.grantor is a valid user, and that's it.\\n\\n0002 then revises the behavior substantially further to make role\\ngrants work like other grants. The grantor of record is required to be\\na user with ADMIN OPTION on the grant, or the bootstrap superuser,\\njust as for other object types the grantor of record must have GRANT\\nOPTION or be the object owner (but roles don't have owners). Dependent\\ngrants are tracked and must be revoked before the grants upon which\\nthey depend, but REVOKE .. CASCADE now works. Dependent grants must be\\nacyclic: you can't have alice getting ADMIN OPTION from bob and bob\\ngetting it from alice; somebody's got to get it from the bootstrap\\nsuperuser. This is all just by analogy with what we do for grants on\\nobject types, and making role grants do something similar instead of\\nthe completely random treatment we have at present.\\n\\nI believe that these patches are mostly complete, but I think that\\ndumpRoleMembership() probably needs some more work. I don't know what\\nexactly, but there's nothing to cause it to dump the role grants in an\\norder that will create dependent grants after the things that they\\ndepend on, which seems essential.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 26 Jul 2022 12:46:07 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> I believe that these patches are mostly complete, but I think that\\n> dumpRoleMembership() probably needs some more work. I don't know what\\n> exactly, but there's nothing to cause it to dump the role grants in an\\n> order that will create dependent grants after the things that they\\n> depend on, which seems essential.\\n\\nOK, so I fixed that, and also updated the documentation a bit more. I\\nthink these patches are basically done, and I'd like to get them\\ncommitted before too much more time goes by, because I have other\\nthings that depend on this which I also want to get done for this\\nrelease. Anybody object?\\n\\nI'm hoping not, because, while this is a behavior change, the current\\nstate of play in this area is just terrible. To my knowledge, this is\\nthe only place in the system where we allow a dangling OID reference\\nin a catalog table to persist after the object to which it refers has\\nbeen dropped. I believe it's also the object type where multiple\\ngrants by different grantors aren't tracked separately, and where the\\ngrantor need not themselves have the permission being granted. It\\ndoesn't really look like any of these things were intentional behavior\\nso much as just ... nobody ever bothered to write the code to make it\\nwork properly. I'm hoping the fact that I have now done that will be\\nviewed as a good thing, but maybe that won't turn out to be the case.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Thu, 28 Jul 2022 15:09:32 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Thu, Jul 28, 2022 at 12:09 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n\\n> On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com>\\n> wrote:\\n> > I believe that these patches are mostly complete, but I think that\\n> > dumpRoleMembership() probably needs some more work. I don't know what\\n> > exactly, but there's nothing to cause it to dump the role grants in an\\n> > order that will create dependent grants after the things that they\\n> > depend on, which seems essential.\\n>\\n> OK, so I fixed that, and also updated the documentation a bit more. I\\n> think these patches are basically done, and I'd like to get them\\n> committed before too much more time goes by, because I have other\\n> things that depend on this which I also want to get done for this\\n> release. Anybody object?\\n>\\n> I'm hoping not, because, while this is a behavior change, the current\\n> state of play in this area is just terrible. To my knowledge, this is\\n> the only place in the system where we allow a dangling OID reference\\n> in a catalog table to persist after the object to which it refers has\\n> been dropped. I believe it's also the object type where multiple\\n> grants by different grantors aren't tracked separately, and where the\\n> grantor need not themselves have the permission being granted. It\\n> doesn't really look like any of these things were intentional behavior\\n> so much as just ... nobody ever bothered to write the code to make it\\n> work properly. I'm hoping the fact that I have now done that will be\\n> viewed as a good thing, but maybe that won't turn out to be the case.\\n>\\n>\\nI suggest changing \\\\du memberof to output something like this:\\n\\nselect r.rolname,\\narray(\\n select format('%s:%s/%s',\\n b.rolname,\\n case when m.admin_option then 'admin' else 'member' end,\\n g.rolname)\\n from pg_catalog.pg_auth_members m\\n join pg_catalog.pg_roles b on (m.roleid = b.oid)\\n join pg_catalog.pg_roles g on (m.grantor = g.oid)\\n where m.member = r.oid\\n) as memberof\\nfrom pg_catalog.pg_roles r where r.rolname !~ '^pg_';\\n\\n rolname | memberof\\n---------+------------------------------------\\n vagrant | {}\\n o | {}\\n a | {o:admin/p,o:admin/vagrant}\\n x | {o:admin/a,p:member/vagrant}\\n b | {o:admin/a}\\n p | {o:admin/vagrant}\\n y | {x:member/vagrant}\\n q | {}\\n r | {q:admin/vagrant}\\n s | {}\\n t | {q:admin/vagrant,s:member/vagrant}\\n\\n\\n(needs sorting, tried to model it after ACL - column privileges\\nspecifically)\\n\\n=> \\\\dp mytable\\n Access privileges\\n Schema | Name | Type | Access privileges | Column privileges |\\nPolicies\\n--------+---------+-------+-----------------------+-----------------------+----------\\n public | mytable | table | miriam=arwdDxt/miriam+| col1: +|\\n | | | =r/miriam +| miriam_rw=rw/miriam |\\n | | | admin=arw/miriam | |\\n(1 row)\\n\\nIf we aren't dead set on having \\\\du and \\\\dg be aliases for each other I'd\\nrather redesign \\\\dg (or add a new meta-command) to be a group-centric view\\nof this exact same data instead of user-centric one. Namely it has a\\n\\\"members\\\" column instead of \\\"memberof\\\" and have it output, one line per\\nmember:\\n\\nuser=[admin|member]/grantor\\n\\nI looked over the rest of the patch and played with the circularity a bit,\\nwhich motivated the expanded info in \\\\du, and the confirmation that two\\nseparate admin grants that are not circular can exist.\\n\\nI don't have any meaningful insight as to breaking things with these\\nchanges but I am strongly in favor of tightening this up and formalizing it.\\n\\nDavid J.\\n\\nOn Thu, Jul 28, 2022 at 12:09 PM Robert Haas <robertmhaas@gmail.com> wrote:On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> I believe that these patches are mostly complete, but I think that\\n> dumpRoleMembership() probably needs some more work. I don't know what\\n> exactly, but there's nothing to cause it to dump the role grants in an\\n> order that will create dependent grants after the things that they\\n> depend on, which seems essential.\\n\\nOK, so I fixed that, and also updated the documentation a bit more. I\\nthink these patches are basically done, and I'd like to get them\\ncommitted before too much more time goes by, because I have other\\nthings that depend on this which I also want to get done for this\\nrelease. Anybody object?\\n\\nI'm hoping not, because, while this is a behavior change, the current\\nstate of play in this area is just terrible. To my knowledge, this is\\nthe only place in the system where we allow a dangling OID reference\\nin a catalog table to persist after the object to which it refers has\\nbeen dropped. I believe it's also the object type where multiple\\ngrants by different grantors aren't tracked separately, and where the\\ngrantor need not themselves have the permission being granted. It\\ndoesn't really look like any of these things were intentional behavior\\nso much as just ... nobody ever bothered to write the code to make it\\nwork properly. I'm hoping the fact that I have now done that will be\\nviewed as a good thing, but maybe that won't turn out to be the case.I suggest changing \\\\du memberof to output something like this:select r.rolname, array( select format('%s:%s/%s', b.rolname, case when m.admin_option then 'admin' else 'member' end, g.rolname) from pg_catalog.pg_auth_members m join pg_catalog.pg_roles b on (m.roleid = b.oid) join pg_catalog.pg_roles g on (m.grantor = g.oid) where m.member = r.oid) as memberoffrom pg_catalog.pg_roles r where r.rolname !~ '^pg_'; rolname | memberof ---------+------------------------------------ vagrant | {} o | {} a | {o:admin/p,o:admin/vagrant} x | {o:admin/a,p:member/vagrant} b | {o:admin/a} p | {o:admin/vagrant} y | {x:member/vagrant} q | {} r | {q:admin/vagrant} s | {} t | {q:admin/vagrant,s:member/vagrant}(needs sorting, tried to model it after ACL - column privileges specifically)=> \\\\dp mytable Access privileges Schema | Name | Type | Access privileges | Column privileges | Policies--------+---------+-------+-----------------------+-----------------------+---------- public | mytable | table | miriam=arwdDxt/miriam+| col1: +| | | | =r/miriam +| miriam_rw=rw/miriam | | | | admin=arw/miriam | |(1 row)If we aren't dead set on having \\\\du and \\\\dg be aliases for each other I'd rather redesign \\\\dg (or add a new meta-command) to be a group-centric view of this exact same data instead of user-centric one. Namely it has a \\\"members\\\" column instead of \\\"memberof\\\" and have it output, one line per member:user=[admin|member]/grantorI looked over the rest of the patch and played with the circularity a bit, which motivated the expanded info in \\\\du, and the confirmation that two separate admin grants that are not circular can exist.I don't have any meaningful insight as to breaking things with these changes but I am strongly in favor of tightening this up and formalizing it.David J.\",\n \"msg_date\": \"Thu, 28 Jul 2022 14:17:06 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Thu, Jul 28, 2022 at 5:17 PM David G. Johnston\\n<david.g.johnston@gmail.com> wrote:\\n> I suggest changing \\\\du memberof to output something like this:\\n>\\n> rolname | memberof\\n> ---------+------------------------------------\\n> vagrant | {}\\n> r | {q:admin/vagrant}\\n> t | {q:admin/vagrant,s:member/vagrant}\\n>\\n> (needs sorting, tried to model it after ACL - column privileges specifically)\\n\\nI don't know. I agree with you that we should probably think about\\nchanging the \\\\du output, but I'm not sure if I like this particular\\nidea about how to do it. I mean, the ACL format that we use for tables\\nand other objects is basically an internal format which we throw at\\nthe user, hoping they'll know how to interpret it. I don't know if\\nit's what we should pick when we don't have that kind of internal\\nformat already. On the other hand, consistency is worth something, and\\nI'm not sure that I have a better idea.\\n\\nhttps://commitfest.postgresql.org/38/3744/ might affect what we want\\nto do here, too.\\n\\n> If we aren't dead set on having \\\\du and \\\\dg be aliases for each other I'd rather redesign \\\\dg (or add a new meta-command) to be a group-centric view of this exact same data instead of user-centric one. Namely it has a \\\"members\\\" column instead of \\\"memberof\\\" and have it output, one line per member:\\n>\\n> user=[admin|member]/grantor\\n\\nThat seems like a topic for a separate thread, but I agree that a\\nflipped view of this data would be more useful than using two letters\\nof the alphabet for exactly the same thing, especially given that\\nwe're pretty short on unused letters.\\n\\n> I don't have any meaningful insight as to breaking things with these changes but I am strongly in favor of tightening this up and formalizing it.\\n\\nCool.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 29 Jul 2022 08:46:06 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > I believe that these patches are mostly complete, but I think that\\n> > dumpRoleMembership() probably needs some more work. I don't know what\\n> > exactly, but there's nothing to cause it to dump the role grants in an\\n> > order that will create dependent grants after the things that they\\n> > depend on, which seems essential.\\n> \\n> OK, so I fixed that, and also updated the documentation a bit more. I\\n> think these patches are basically done, and I'd like to get them\\n> committed before too much more time goes by, because I have other\\n> things that depend on this which I also want to get done for this\\n> release. Anybody object?\\n\\nThanks for working on this.\\n\\nSubject: [PATCH v3 1/2] Ensure that pg_auth_members.grantor is always valid.\\n\\ndiff --git a/src/backend/commands/user.c b/src/backend/commands/user.c\\nindex 94135fdd6b..258943094a 100644\\n--- a/src/backend/commands/user.c\\n+++ b/src/backend/commands/user.c\\n@@ -919,7 +920,7 @@ DropRole(DropRoleStmt *stmt)\\n \\n \\t/*\\n \\t * Scan the pg_authid relation to find the Oid of the role(s) to be\\n-\\t * deleted.\\n+\\t * deleted and perform prleliminary permissions and sanity checks.\\n\\nShould be preliminary, I'm guessing.\\n\\nOverall, this looks like a solid improvement.\\n\\nSubject: [PATCH v3 2/2] Make role grant system more consistent with other\\n privileges.\\n\\n> Previously, only the superuser could specify GRANTED BY with a user\\n> other than the current user. Relax that rule to allow the grantor\\n> to be any role whose privileges the current user posseses. This\\n> doesn't improve compatibility with what we do for other object types,\\n> where support for GRANTED BY is entirely vestigial, but it makes this\\n> feature more usable and seems to make sense to change at the same time\\n> we're changing related behaviors.\\n\\nPresumably the GRANTED BY user in this case still has to have the\\nability to have performed the GRANT themselves? Looks that way below\\nand it's just the commit message, but was the first question that came\\nto mind when I read through this.\\n\\ndiff --git a/doc/src/sgml/ref/grant.sgml b/doc/src/sgml/ref/grant.sgml\\nindex f744b05b55..1f828d386a 100644\\n--- a/doc/src/sgml/ref/grant.sgml\\n+++ b/doc/src/sgml/ref/grant.sgml\\n@@ -267,8 +267,14 @@ GRANT <replaceable class=\\\"parameter\\\">role_name</replaceable> [, ...] TO <replace\\n \\n <para>\\n If <literal>GRANTED BY</literal> is specified, the grant is recorded as\\n- having been done by the specified role. Only database superusers may\\n- use this option, except when it names the same role executing the command.\\n+ having been done by the specified role. A user can only attribute a grant\\n+ to another role if they possess the privileges of that role. A role can\\n+ only be recorded as a grantor if has <literal>ADMIN OPTION</literal> on\\n\\nShould be: if they have\\n\\n+ a role or is the bootstrap superuser. When a grant is recorded as having\\n\\non *that* role seems like it'd be better. And maybe 'or if they are the\\nbootstrap superuser'?\\n\\ndiff --git a/src/backend/commands/user.c b/src/backend/commands/user.c\\nindex 258943094a..8ab2fecf3a 100644\\n--- a/src/backend/commands/user.c\\n+++ b/src/backend/commands/user.c\\n@@ -805,11 +842,12 @@ AlterRole(ParseState *pstate, AlterRoleStmt *stmt)\\n \\t\\tif (stmt->action == +1) /* add members to role */\\n \\t\\t\\tAddRoleMems(rolename, roleid,\\n \\t\\t\\t\\t\\t\\trolemembers, roleSpecsToIds(rolemembers),\\n-\\t\\t\\t\\t\\t\\tGetUserId(), false);\\n+\\t\\t\\t\\t\\t\\tInvalidOid, false);\\n \\t\\telse if (stmt->action == -1)\\t/* drop members from role */\\n \\t\\t\\tDelRoleMems(rolename, roleid,\\n \\t\\t\\t\\t\\t\\trolemembers, roleSpecsToIds(rolemembers),\\n-\\t\\t\\t\\t\\t\\tfalse);\\n+\\t\\t\\t\\t\\t\\tInvalidOid, false, DROP_RESTRICT);\\t/* XXX sketchy - hint\\n+\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t * may mislead */\\n \\t}\\n\\nThis comment seems a little concerning..? Also isn't very clear.\\n\\n@@ -1027,7 +1065,7 @@ DropRole(DropRoleStmt *stmt)\\n \\n \\t\\twhile (HeapTupleIsValid(tmp_tuple = systable_getnext(sscan)))\\n \\t\\t{\\n-\\t\\t\\tForm_pg_auth_members\\tauthmem_form;\\n+\\t\\t\\tForm_pg_auth_members authmem_form;\\n \\n \\t\\t\\tauthmem_form = (Form_pg_auth_members) GETSTRUCT(tmp_tuple);\\n \\t\\t\\tdeleteSharedDependencyRecordsFor(AuthMemRelationId,\\n\\nSome random whitespace changes that seems a bit odd given that they\\nshould have been already correct thanks to pgindent- will these end up\\njust getting undone again?\\n\\n@@ -1543,14 +1578,94 @@ AddRoleMems(const char *rolename, Oid roleid,\\n \\t\\t\\t\\t\\t(errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n \\t\\t\\t\\t\\t errmsg(\\\"role \\\\\\\"%s\\\\\\\" is a member of role \\\\\\\"%s\\\\\\\"\\\",\\n \\t\\t\\t\\t\\t\\t\\trolename, get_rolespec_name(memberRole))));\\n+\\t}\\n+\\n+\\t/*\\n+\\t * Disallow attempts to grant ADMIN OPTION back to a user who granted it\\n+\\t * to you, similar to what check_circularity does for ACLs. We want the\\n+\\t * chains of grants to remain acyclic, so that it's always possible to use\\n+\\t * REVOKE .. CASCADE to clean up all grants that depend on the one being\\n+\\t * revoked.\\n+\\t *\\n+\\t * NB: This check might look redundant with the check for membership\\n+\\t * loops above, but it isn't. That's checking for role-member loop (e.g.\\n+\\t * A is a member of B and B is a member of A) while this is checking for\\n+\\t * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and now B, who\\n+\\t * has no other source of ADMIN OPTION on X, tries to give ADMIN OPTION\\n+\\t * on X back to A).\\n+\\t */\\n\\nWith this exact scenario, wouldn't it just be a no-op as A must have\\nADMIN OPTION already on X? The spec says that no cycles of role\\nauthorizations are allowed. Presumably we'd continue this for other\\nGRANT'able things which can be further GRANT'd (should we add them) in\\nthe future? Just trying to think ahead a bit here in case it's\\nworthwhile. Those would likely be ABC WITH GRANT OPTION too, right?\\n\\n+\\tif (admin_opt && grantorId != BOOTSTRAP_SUPERUSERID)\\n+\\t{\\n+\\t\\tCatCList *memlist;\\n+\\t\\tRevokeRoleGrantAction *actions;\\n+\\t\\tint\\t\\t\\ti;\\n+\\n+\\t\\t/* Get the list of members for this role. */\\n+\\t\\tmemlist = SearchSysCacheList1(AUTHMEMROLEMEM,\\n+\\t\\t\\t\\t\\t\\t\\t\\t\\t ObjectIdGetDatum(roleid));\\n+\\n+\\t\\t/*\\n+\\t\\t * Figure out what would happen if we removed all existing grants to\\n+\\t\\t * every role to which we've been asked to make a new grant.\\n+\\t\\t */\\n+\\t\\tactions = initialize_revoke_actions(memlist);\\n+\\t\\tforeach(iditem, memberIds)\\n+\\t\\t{\\n+\\t\\t\\tOid\\t\\t\\tmemberid = lfirst_oid(iditem);\\n+\\n+\\t\\t\\tif (memberid == BOOTSTRAP_SUPERUSERID)\\n+\\t\\t\\t\\tereport(ERROR,\\n+\\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n+\\t\\t\\t\\t\\t\\t errmsg(\\\"grants with admin options cannot be circular\\\")));\\n+\\t\\t\\tplan_member_revoke(memlist, actions, memberid);\\n+\\t\\t}\\n\\nI don't see a regression test added which produces the above error\\nmessage. The memberid == BOOTSTRAP_SUPERUSERID seems odd too?\\n\\n+\\t\\t/*\\n+\\t\\t * If the result would be that the grantor role would no longer have\\n+\\t\\t * the ability to perform the grant, then the proposed grant would\\n+\\t\\t * create a circularity.\\n+\\t\\t */\\n+\\t\\tfor (i = 0; i < memlist->n_members; ++i)\\n+\\t\\t{\\n+\\t\\t\\tHeapTuple\\tauthmem_tuple;\\n+\\t\\t\\tForm_pg_auth_members authmem_form;\\n+\\n+\\t\\t\\tauthmem_tuple = &memlist->members[i]->tuple;\\n+\\t\\t\\tauthmem_form = (Form_pg_auth_members) GETSTRUCT(authmem_tuple);\\n+\\n+\\t\\t\\tif (actions[i] == RRG_NOOP &&\\n+\\t\\t\\t\\tauthmem_form->member == grantorId &&\\n+\\t\\t\\t\\tauthmem_form->admin_option)\\n+\\t\\t\\t\\tbreak;\\n+\\t\\t}\\n+\\t\\tif (i >= memlist->n_members)\\n+\\t\\t\\tereport(ERROR,\\n+\\t\\t\\t\\t\\t(errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n+\\t\\t\\t\\t\\t errmsg(\\\"admin options cannot be granted back to your own grantor\\\")));\\n\\nI do see this in the regression tests. There though, the GRANTs are\\nbeing performed by someone else, so saying 'your' isn't quite right.\\nI'm trying to get this review out sooner than later and so I might be\\nmissing something, but looking at the regression test for this and these\\nerror messages, feels like the 'circular' error message makes more sense\\nthan the 'your own grantor' message that actually ends up being\\nreturned in that regression test.\\n\\n@@ -1637,17 +1737,22 @@ AddRoleMems(const char *rolename, Oid roleid,\\n * roleid: OID of role to del from\\n * memberSpecs: list of RoleSpec of roles to del (used only for error messages)\\n * memberIds: OIDs of roles to del\\n+ * grantorId: who is revoking the membership\\n * admin_opt: remove admin option only?\\n */\\n static void\\n DelRoleMems(const char *rolename, Oid roleid,\\n \\t\\t\\tList *memberSpecs, List *memberIds,\\n-\\t\\t\\tbool admin_opt)\\n+\\t\\t\\tOid grantorId, bool admin_opt, DropBehavior behavior)\\n\\n\\nThe comment above DropRoleMems missed adding a description for\\nthe 'behavior' parameter.\\n\\n@@ -1669,40 +1774,69 @@ DelRoleMems(const char *rolename, Oid roleid,\\n+\\t/*\\n+\\t * We may need to recurse to dependent privileges if DROP_CASCADE was\\n+\\t * specified, or refuse to perform the operation if dependent privileges\\n+\\t * exist and DROP_RECURSE was specified. plan_single_revoke() will\\n+\\t * figure out what to do with each catalog tuple.\\n+\\t */\\n\\nPretty sure that should be DROP_RESTRICT, not DROP_RECURSE.\\n\\n+/*\\n+ * Sanity-check, or infer, the grantor for a GRANT or REVOKE statement\\n+ * targeting a role.\\n+ *\\n+ * The grantor must always be either a role with ADMIN OPTION on the role in\\n+ * which membership is being granted, or the bootstrap superuser. This is\\n+ * similar to the restriction enforced by select_best_grantor, except that\\n+ * roles don't have owners, so we regard the bootstrap superuser as the\\n+ * implicit owner.\\n+ *\\n+ * The return value is the OID to be regarded as the grantor when executing\\n+ * the operation.\\n+ */\\n+static Oid\\n+check_role_grantor(Oid currentUserId, Oid roleid, Oid grantorId, bool is_grant)\\n\\nAs this also does some permission checks, it seems like it'd be good to\\nmention that in the function description. Maybe also in the places that\\ncall into this function with the expectation that the privilege check\\nwill be taken care of here.\\n\\nIndeed, I wonder if maybe we should really split this function into two\\nas the \\\"give me what the best grantor is\\\" is a fair bit different from\\n\\\"check if this user has permission to grant as this role\\\". As noted in\\nthe comments, the current function also only does privilege checking in\\nsome case- when InvalidOid is passed in we've also already done\\npermissions checks to make sure that the GRANT will succeed.\\n\\n+/*\\n+ * Initialize an array of RevokeRoleGrantAction objects.\\n+ *\\n+ * 'memlist' should be a list of all grants for the target role.\\n+ *\\n+ * We here construct an array indicating that no actions are to be performed;\\n+ * that is, every element is intiially RRG_NOOP.\\n+ */\\n\\n\\\"We here construct\\\" seems odd wording to me. Maybe \\\"Here we construct\\\"?\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Sun, 31 Jul 2022 14:18:27 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Stephen Frost <sfrost@snowman.net> writes:\\n> * Robert Haas (robertmhaas@gmail.com) wrote:\\n>> OK, so I fixed that, and also updated the documentation a bit more. I\\n>> think these patches are basically done, and I'd like to get them\\n>> committed before too much more time goes by, because I have other\\n>> things that depend on this which I also want to get done for this\\n>> release. Anybody object?\\n\\n> Thanks for working on this.\\n\\nIndeed. I've not read the patch, but I just wanted to mention that\\nthe cfbot shows it as failing regression tests on all platforms.\\nPossibly a conflict with some recent commit?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 31 Jul 2022 14:33:54 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Sun, Jul 31, 2022 at 11:18 AM Stephen Frost <sfrost@snowman.net> wrote:\\n\\n> Greetings,\\n>\\n> * Robert Haas (robertmhaas@gmail.com) wrote:\\n> > On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com>\\n> wrote:\\n>\\n> + }\\n> +\\n> + /*\\n> + * Disallow attempts to grant ADMIN OPTION back to a user who\\n> granted it\\n> + * to you, similar to what check_circularity does for ACLs. We\\n> want the\\n> + * chains of grants to remain acyclic, so that it's always\\n> possible to use\\n> + * REVOKE .. CASCADE to clean up all grants that depend on the one\\n> being\\n> + * revoked.\\n> + *\\n> + * NB: This check might look redundant with the check for\\n> membership\\n> + * loops above, but it isn't. That's checking for role-member loop\\n> (e.g.\\n> + * A is a member of B and B is a member of A) while this is\\n> checking for\\n> + * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and\\n> now B, who\\n> + * has no other source of ADMIN OPTION on X, tries to give ADMIN\\n> OPTION\\n> + * on X back to A).\\n> + */\\n>\\n> With this exact scenario, wouldn't it just be a no-op as A must have\\n> ADMIN OPTION already on X? The spec says that no cycles of role\\n> authorizations are allowed.\\n\\n\\nRole A must have admin option for X to grant membership in X (with or\\nwithout admin option) to B. But that doesn't preclude A from getting\\nanother admin option from someone else. That someone else cannot be\\nsomeone to whom they gave admin option to however. So B cannot grant admin\\noption back to A but role P could if it was basically a sibling of A (i.e.,\\nboth getting their initial admin option from someone else).\\n\\nIf they do have admin option twice it should be possible to drop one of\\nthem, the prohibition should be on dropping the only admin option\\npermission a role has for some other role. The commit message for 2\\ncontemplates this though I haven't gone through the revocation code in\\ndetail.\\n\\n\\n> I'm trying to get this review out sooner than later and so I might be\\n> missing something, but looking at the regression test for this and these\\n> error messages, feels like the 'circular' error message makes more sense\\n> than the 'your own grantor' message that actually ends up being\\n> returned in that regression test.\\n>\\n\\nHaving a more specific error seems reasonable, faster to track down what\\nthe problem is.\\n\\nI think that the whole graph dynamic of this might need some presentation\\nwork (messages and/or psql and/or functions) ; but assuming the errors are\\nhandled improved messages and/or presentation of graphs can be a separate\\nenhancement.\\n\\nDavid J.\\n\\nOn Sun, Jul 31, 2022 at 11:18 AM Stephen Frost <sfrost@snowman.net> wrote:Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n+ }\\n+\\n+ /*\\n+ * Disallow attempts to grant ADMIN OPTION back to a user who granted it\\n+ * to you, similar to what check_circularity does for ACLs. We want the\\n+ * chains of grants to remain acyclic, so that it's always possible to use\\n+ * REVOKE .. CASCADE to clean up all grants that depend on the one being\\n+ * revoked.\\n+ *\\n+ * NB: This check might look redundant with the check for membership\\n+ * loops above, but it isn't. That's checking for role-member loop (e.g.\\n+ * A is a member of B and B is a member of A) while this is checking for\\n+ * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and now B, who\\n+ * has no other source of ADMIN OPTION on X, tries to give ADMIN OPTION\\n+ * on X back to A).\\n+ */\\n\\nWith this exact scenario, wouldn't it just be a no-op as A must have\\nADMIN OPTION already on X? The spec says that no cycles of role\\nauthorizations are allowed.Role A must have admin option for X to grant membership in X (with or without admin option) to B. But that doesn't preclude A from getting another admin option from someone else. That someone else cannot be someone to whom they gave admin option to however. So B cannot grant admin option back to A but role P could if it was basically a sibling of A (i.e., both getting their initial admin option from someone else).If they do have admin option twice it should be possible to drop one of them, the prohibition should be on dropping the only admin option permission a role has for some other role. The commit message for 2 contemplates this though I haven't gone through the revocation code in detail. \\nI'm trying to get this review out sooner than later and so I might be\\nmissing something, but looking at the regression test for this and these\\nerror messages, feels like the 'circular' error message makes more sense\\nthan the 'your own grantor' message that actually ends up being\\nreturned in that regression test.Having a more specific error seems reasonable, faster to track down what the problem is.I think that the whole graph dynamic of this might need some presentation work (messages and/or psql and/or functions) ; but assuming the errors are handled improved messages and/or presentation of graphs can be a separate enhancement.David J.\",\n \"msg_date\": \"Sun, 31 Jul 2022 11:43:48 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\nOn Sun, Jul 31, 2022 at 11:44 David G. Johnston <david.g.johnston@gmail.com>\\nwrote:\\n\\n> On Sun, Jul 31, 2022 at 11:18 AM Stephen Frost <sfrost@snowman.net> wrote:\\n>\\n>> Greetings,\\n>>\\n>> * Robert Haas (robertmhaas@gmail.com) wrote:\\n>> > On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com>\\n>> wrote:\\n>>\\n>> + }\\n>> +\\n>> + /*\\n>> + * Disallow attempts to grant ADMIN OPTION back to a user who\\n>> granted it\\n>> + * to you, similar to what check_circularity does for ACLs. We\\n>> want the\\n>> + * chains of grants to remain acyclic, so that it's always\\n>> possible to use\\n>> + * REVOKE .. CASCADE to clean up all grants that depend on the\\n>> one being\\n>> + * revoked.\\n>> + *\\n>> + * NB: This check might look redundant with the check for\\n>> membership\\n>> + * loops above, but it isn't. That's checking for role-member\\n>> loop (e.g.\\n>> + * A is a member of B and B is a member of A) while this is\\n>> checking for\\n>> + * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and\\n>> now B, who\\n>> + * has no other source of ADMIN OPTION on X, tries to give ADMIN\\n>> OPTION\\n>> + * on X back to A).\\n>> + */\\n>>\\n>> With this exact scenario, wouldn't it just be a no-op as A must have\\n>> ADMIN OPTION already on X? The spec says that no cycles of role\\n>> authorizations are allowed.\\n>\\n>\\nI’ve realized that what I hadn’t been contemplating here is actually that\\nthe GRANT from B to A for X wouldn’t be redundant because grantor is part\\nof the key (A got the right from someone else, but this would be giving it\\nto A from B and therefore would be distinct and would also create a loop\\nwhich is no good). Haven’t got a good idea on how to improve on the\\ncomment based off of that though it still feels like it could be clearer.\\nIf I think of something, I’ll share it.\\n\\nRole A must have admin option for X to grant membership in X (with or\\n> without admin option) to B. But that doesn't preclude A from getting\\n> another admin option from someone else. That someone else cannot be\\n> someone to whom they gave admin option to however. So B cannot grant admin\\n> option back to A but role P could if it was basically a sibling of A (i.e.,\\n> both getting their initial admin option from someone else).\\n>\\n\\nRight but that wasn’t what I had been trying to get at above.\\n\\nIf they do have admin option twice it should be possible to drop one of\\n> them, the prohibition should be on dropping the only admin option\\n> permission a role has for some other role. The commit message for 2\\n> contemplates this though I haven't gone through the revocation code in\\n> detail.\\n>\\n\\nYes, think I agree with this also- if A has been given the WITH ADMIN right\\nfrom Q and P to GRANT X to other roles, and uses that to GRANT X to B, then\\nthe GRANT of X to B should be retained even if Q decides to revoke their\\nGRANT as A still has the right from P. If both remove the right, however,\\neither B should lose the right (if CASCADE was passed in) or an error\\nshould be returned saying that there’s a dependent GRANT and CASCADE wasn’t\\ngiven.\\n\\nI'm trying to get this review out sooner than later and so I might be\\n>> missing something, but looking at the regression test for this and these\\n>> error messages, feels like the 'circular' error message makes more sense\\n>> than the 'your own grantor' message that actually ends up being\\n>> returned in that regression test.\\n>>\\n>\\n> Having a more specific error seems reasonable, faster to track down what\\n> the problem is.\\n>\\n\\nYeah, but also making sure that all the error messages we have in this area\\nare in the regression test output would be good.\\n\\nMakes me wonder if we might try to figure out a way to globally check for\\nthat. I suppose one could review coverage.p.o for any ereport() calls that\\naren’t ever called. I wonder what that would turn up.\\n\\nI think that the whole graph dynamic of this might need some presentation\\n> work (messages and/or psql and/or functions) ; but assuming the errors are\\n> handled improved messages and/or presentation of graphs can be a separate\\n> enhancement.\\n>\\n\\nYes, we can further improve this later too but that doesn’t mean we should\\njust commit this as-is when some deficiencies have been pointed out. If the\\nonly comments were “would be good to improve this error message but I\\nhaven’t got a great idea how”, then sure, but there were other items\\npointed out which were clear corrections and we should make sure to cover\\nin the regression tests all these scenarios that we are checking for and\\nerroring on, lest we end up breaking them unintentionally later.\\n\\nThanks,\\n\\nStephen\\n\\n>\\n\\nGreetings,On Sun, Jul 31, 2022 at 11:44 David G. Johnston <david.g.johnston@gmail.com> wrote:On Sun, Jul 31, 2022 at 11:18 AM Stephen Frost <sfrost@snowman.net> wrote:Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Tue, Jul 26, 2022 at 12:46 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n+ }\\n+\\n+ /*\\n+ * Disallow attempts to grant ADMIN OPTION back to a user who granted it\\n+ * to you, similar to what check_circularity does for ACLs. We want the\\n+ * chains of grants to remain acyclic, so that it's always possible to use\\n+ * REVOKE .. CASCADE to clean up all grants that depend on the one being\\n+ * revoked.\\n+ *\\n+ * NB: This check might look redundant with the check for membership\\n+ * loops above, but it isn't. That's checking for role-member loop (e.g.\\n+ * A is a member of B and B is a member of A) while this is checking for\\n+ * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and now B, who\\n+ * has no other source of ADMIN OPTION on X, tries to give ADMIN OPTION\\n+ * on X back to A).\\n+ */\\n\\nWith this exact scenario, wouldn't it just be a no-op as A must have\\nADMIN OPTION already on X? The spec says that no cycles of role\\nauthorizations are allowed.I’ve realized that what I hadn’t been contemplating here is actually that the GRANT from B to A for X wouldn’t be redundant because grantor is part of the key (A got the right from someone else, but this would be giving it to A from B and therefore would be distinct and would also create a loop which is no good). Haven’t got a good idea on how to improve on the comment based off of that though it still feels like it could be clearer. If I think of something, I’ll share it.Role A must have admin option for X to grant membership in X (with or without admin option) to B. But that doesn't preclude A from getting another admin option from someone else. That someone else cannot be someone to whom they gave admin option to however. So B cannot grant admin option back to A but role P could if it was basically a sibling of A (i.e., both getting their initial admin option from someone else).Right but that wasn’t what I had been trying to get at above.If they do have admin option twice it should be possible to drop one of them, the prohibition should be on dropping the only admin option permission a role has for some other role. The commit message for 2 contemplates this though I haven't gone through the revocation code in detail.Yes, think I agree with this also- if A has been given the WITH ADMIN right from Q and P to GRANT X to other roles, and uses that to GRANT X to B, then the GRANT of X to B should be retained even if Q decides to revoke their GRANT as A still has the right from P. If both remove the right, however, either B should lose the right (if CASCADE was passed in) or an error should be returned saying that there’s a dependent GRANT and CASCADE wasn’t given.\\nI'm trying to get this review out sooner than later and so I might be\\nmissing something, but looking at the regression test for this and these\\nerror messages, feels like the 'circular' error message makes more sense\\nthan the 'your own grantor' message that actually ends up being\\nreturned in that regression test.Having a more specific error seems reasonable, faster to track down what the problem is.Yeah, but also making sure that all the error messages we have in this area are in the regression test output would be good.Makes me wonder if we might try to figure out a way to globally check for that. I suppose one could review coverage.p.o for any ereport() calls that aren’t ever called. I wonder what that would turn up.I think that the whole graph dynamic of this might need some presentation work (messages and/or psql and/or functions) ; but assuming the errors are handled improved messages and/or presentation of graphs can be a separate enhancement.Yes, we can further improve this later too but that doesn’t mean we should just commit this as-is when some deficiencies have been pointed out. If the only comments were “would be good to improve this error message but I haven’t got a great idea how”, then sure, but there were other items pointed out which were clear corrections and we should make sure to cover in the regression tests all these scenarios that we are checking for and erroring on, lest we end up breaking them unintentionally later.Thanks,Stephen\",\n \"msg_date\": \"Sun, 31 Jul 2022 14:19:34 -0700\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Sun, Jul 31, 2022 at 2:18 PM Stephen Frost <sfrost@snowman.net> wrote:\\n> Thanks for working on this.\\n\\nThanks for the review.\\n\\n> > Previously, only the superuser could specify GRANTED BY with a user\\n> > other than the current user. Relax that rule to allow the grantor\\n> > to be any role whose privileges the current user posseses. This\\n> > doesn't improve compatibility with what we do for other object types,\\n> > where support for GRANTED BY is entirely vestigial, but it makes this\\n> > feature more usable and seems to make sense to change at the same time\\n> > we're changing related behaviors.\\n>\\n> Presumably the GRANTED BY user in this case still has to have the\\n> ability to have performed the GRANT themselves? Looks that way below\\n> and it's just the commit message, but was the first question that came\\n> to mind when I read through this.\\n\\nYes. The previous paragraph in this commit message seems to cover this\\npoint pretty thoroughly.\\n\\n> <para>\\n> If <literal>GRANTED BY</literal> is specified, the grant is recorded as\\n> - having been done by the specified role. Only database superusers may\\n> - use this option, except when it names the same role executing the command.\\n> + having been done by the specified role. A user can only attribute a grant\\n> + to another role if they possess the privileges of that role. A role can\\n> + only be recorded as a grantor if has <literal>ADMIN OPTION</literal> on\\n>\\n> Should be: if they have\\n>\\n> + a role or is the bootstrap superuser. When a grant is recorded as having\\n>\\n> on *that* role seems like it'd be better. And maybe 'or if they are the\\n> bootstrap superuser'?\\n\\nWill fix.\\n\\n> diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c\\n> index 258943094a..8ab2fecf3a 100644\\n> --- a/src/backend/commands/user.c\\n> +++ b/src/backend/commands/user.c\\n> @@ -805,11 +842,12 @@ AlterRole(ParseState *pstate, AlterRoleStmt *stmt)\\n> if (stmt->action == +1) /* add members to role */\\n> AddRoleMems(rolename, roleid,\\n> rolemembers, roleSpecsToIds(rolemembers),\\n> - GetUserId(), false);\\n> + InvalidOid, false);\\n> else if (stmt->action == -1) /* drop members from role */\\n> DelRoleMems(rolename, roleid,\\n> rolemembers, roleSpecsToIds(rolemembers),\\n> - false);\\n> + InvalidOid, false, DROP_RESTRICT); /* XXX sketchy - hint\\n> + * may mislead */\\n> }\\n>\\n> This comment seems a little concerning..? Also isn't very clear.\\n\\nOh right. That was a note to myself to look into that more. And then I\\ndidn't. I'll look into that more and report back.\\n\\n> @@ -1027,7 +1065,7 @@ DropRole(DropRoleStmt *stmt)\\n>\\n> while (HeapTupleIsValid(tmp_tuple = systable_getnext(sscan)))\\n> {\\n> - Form_pg_auth_members authmem_form;\\n> + Form_pg_auth_members authmem_form;\\n>\\n> authmem_form = (Form_pg_auth_members) GETSTRUCT(tmp_tuple);\\n> deleteSharedDependencyRecordsFor(AuthMemRelationId,\\n>\\n> Some random whitespace changes that seems a bit odd given that they\\n> should have been already correct thanks to pgindent- will these end up\\n> just getting undone again?\\n\\nWill fix.\\n\\n> @@ -1543,14 +1578,94 @@ AddRoleMems(const char *rolename, Oid roleid,\\n> (errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n> errmsg(\\\"role \\\\\\\"%s\\\\\\\" is a member of role \\\\\\\"%s\\\\\\\"\\\",\\n> rolename, get_rolespec_name(memberRole))));\\n> + }\\n> +\\n> + /*\\n> + * Disallow attempts to grant ADMIN OPTION back to a user who granted it\\n> + * to you, similar to what check_circularity does for ACLs. We want the\\n> + * chains of grants to remain acyclic, so that it's always possible to use\\n> + * REVOKE .. CASCADE to clean up all grants that depend on the one being\\n> + * revoked.\\n> + *\\n> + * NB: This check might look redundant with the check for membership\\n> + * loops above, but it isn't. That's checking for role-member loop (e.g.\\n> + * A is a member of B and B is a member of A) while this is checking for\\n> + * a member-grantor loop (e.g. A gave ADMIN OPTION to X to B and now B, who\\n> + * has no other source of ADMIN OPTION on X, tries to give ADMIN OPTION\\n> + * on X back to A).\\n> + */\\n>\\n> With this exact scenario, wouldn't it just be a no-op as A must have\\n> ADMIN OPTION already on X? The spec says that no cycles of role\\n> authorizations are allowed. Presumably we'd continue this for other\\n> GRANT'able things which can be further GRANT'd (should we add them) in\\n> the future? Just trying to think ahead a bit here in case it's\\n> worthwhile. Those would likely be ABC WITH GRANT OPTION too, right?\\n\\nI don't believe there's anything novel here - at least there isn't\\nsupposed to be. Here's the equivalent with table privileges:\\n\\nrhaas=# create table t1();\\nCREATE TABLE\\nrhaas=# create role foo;\\nCREATE ROLE\\nrhaas=# create role bar;\\nCREATE ROLE\\nrhaas=# grant select on t1 to foo with grant option;\\nGRANT\\nrhaas=# set role foo;\\nSET\\nrhaas=> grant select on t1 to bar with grant option;\\nGRANT\\nrhaas=> set role bar;\\nSET\\nrhaas=> grant select on t1 to foo with grant option;\\nERROR: grant options cannot be granted back to your own grantor\\n\\n\\n> + if (admin_opt && grantorId != BOOTSTRAP_SUPERUSERID)\\n> + {\\n> + CatCList *memlist;\\n> + RevokeRoleGrantAction *actions;\\n> + int i;\\n> +\\n> + /* Get the list of members for this role. */\\n> + memlist = SearchSysCacheList1(AUTHMEMROLEMEM,\\n> + ObjectIdGetDatum(roleid));\\n> +\\n> + /*\\n> + * Figure out what would happen if we removed all existing grants to\\n> + * every role to which we've been asked to make a new grant.\\n> + */\\n> + actions = initialize_revoke_actions(memlist);\\n> + foreach(iditem, memberIds)\\n> + {\\n> + Oid memberid = lfirst_oid(iditem);\\n> +\\n> + if (memberid == BOOTSTRAP_SUPERUSERID)\\n> + ereport(ERROR,\\n> + (errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n> + errmsg(\\\"grants with admin options cannot be circular\\\")));\\n> + plan_member_revoke(memlist, actions, memberid);\\n> + }\\n>\\n> I don't see a regression test added which produces the above error\\n> message. The memberid == BOOTSTRAP_SUPERUSERID seems odd too?\\n\\nDo we guarantee that the regression tests are running as the bootstrap\\nsuperuser, or just as some superuser? I am a bit reluctant to add a\\nregression test that assumes the former unless we're assuming it\\nalready. For 'make check' it doesn't matter but 'make installcheck' is\\nanother story.\\n\\nThe memberid == BOOTSTRAP_SUPERUSERID case is very much intentional.\\nThe code will detect any loops in the catalog, but the implicit grant\\nto the bootstrap superuser doesn't exist in the catalog\\nrepresentation, so it needs a separate check. I think I should sync\\nthe two error messages though, i.e. this should say \\\"admin options\\ncannot be granted back to your own grantor\\\" like the other one just\\nbelow.\\n\\n> I do see this in the regression tests. There though, the GRANTs are\\n> being performed by someone else, so saying 'your' isn't quite right.\\n> I'm trying to get this review out sooner than later and so I might be\\n> missing something, but looking at the regression test for this and these\\n> error messages, feels like the 'circular' error message makes more sense\\n> than the 'your own grantor' message that actually ends up being\\n> returned in that regression test.\\n\\nI think it's a bit off too, but I didn't invent it. See check_circularity():\\n\\n if ((ACLITEM_GET_GOPTIONS(*mod_aip) & ~own_privs) != 0)\\n ereport(ERROR,\\n (errcode(ERRCODE_INVALID_GRANT_OPERATION),\\n errmsg(\\\"grant options cannot be granted back to your\\nown grantor\\\")));\\n\\nLooks like Tom Lane, vintage 2004, 4b2dafcc0b1a579ef5daaa2728223006d1ff98e9.\\n\\n> The comment above DropRoleMems missed adding a description for\\n> the 'behavior' parameter.\\n\\nWill fix.\\n\\n> @@ -1669,40 +1774,69 @@ DelRoleMems(const char *rolename, Oid roleid,\\n> + /*\\n> + * We may need to recurse to dependent privileges if DROP_CASCADE was\\n> + * specified, or refuse to perform the operation if dependent privileges\\n> + * exist and DROP_RECURSE was specified. plan_single_revoke() will\\n> + * figure out what to do with each catalog tuple.\\n> + */\\n>\\n> Pretty sure that should be DROP_RESTRICT, not DROP_RECURSE.\\n\\nI'm pretty sure you are right.\\n\\n> +/*\\n> + * Sanity-check, or infer, the grantor for a GRANT or REVOKE statement\\n> + * targeting a role.\\n> + *\\n> + * The grantor must always be either a role with ADMIN OPTION on the role in\\n> + * which membership is being granted, or the bootstrap superuser. This is\\n> + * similar to the restriction enforced by select_best_grantor, except that\\n> + * roles don't have owners, so we regard the bootstrap superuser as the\\n> + * implicit owner.\\n> + *\\n> + * The return value is the OID to be regarded as the grantor when executing\\n> + * the operation.\\n> + */\\n> +static Oid\\n> +check_role_grantor(Oid currentUserId, Oid roleid, Oid grantorId, bool is_grant)\\n>\\n> As this also does some permission checks, it seems like it'd be good to\\n> mention that in the function description. Maybe also in the places that\\n> call into this function with the expectation that the privilege check\\n> will be taken care of here.\\n>\\n> Indeed, I wonder if maybe we should really split this function into two\\n> as the \\\"give me what the best grantor is\\\" is a fair bit different from\\n> \\\"check if this user has permission to grant as this role\\\". As noted in\\n> the comments, the current function also only does privilege checking in\\n> some case- when InvalidOid is passed in we've also already done\\n> permissions checks to make sure that the GRANT will succeed.\\n\\nI'll think about this some more, but I don't want to commit to\\nchanging it very much. IMHO, the whole split into AddRoleMems() and\\nDelRoleMems() for what is basically the same operation seems pretty\\ndubious, but this commit's intended purpose is to clean up the\\nbehavior rather than to rewrite the code. So I left the existing logic\\nin AddRoleMems() and DelRoleMems() alone, and when I realized I needed\\nsomething else that was mostly common to both, I made this function\\ninstead of duplicating the logic in two places. I realize there are\\nother ways that it could be split up, and maybe some of those are\\nbetter in theory, but they'd likely also expand the scope of the patch\\nto things that it doesn't quite need to touch. I'm not real keen to go\\nthere. That can be done later, in a separate patch, or never, and I\\ndon't think we'll really be any the worse for it.\\n\\n> +/*\\n> + * Initialize an array of RevokeRoleGrantAction objects.\\n> + *\\n> + * 'memlist' should be a list of all grants for the target role.\\n> + *\\n> + * We here construct an array indicating that no actions are to be performed;\\n> + * that is, every element is intiially RRG_NOOP.\\n> + */\\n>\\n> \\\"We here construct\\\" seems odd wording to me. Maybe \\\"Here we construct\\\"?\\n\\nIt seems completely fine to me, but I'll change it somehow to avoid\\nannoying you. :-)\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Aug 2022 13:00:43 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Sun, Jul 31, 2022 at 2:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Indeed. I've not read the patch, but I just wanted to mention that\\n> the cfbot shows it as failing regression tests on all platforms.\\n> Possibly a conflict with some recent commit?\\n\\nI can't see this on cfbot - either I don't know how to use it\\nproperly, which is quite possible, or the results aren't showing up\\nbecause of the close of the July CommitFest.\\n\\nI tried a rebase locally and it didn't seem to change anything\\nmaterial, not even context lines.\\n\\nCan you provide a link or something that I can look at?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Aug 2022 13:33:12 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Sun, Jul 31, 2022 at 2:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Indeed. I've not read the patch, but I just wanted to mention that\\n>> the cfbot shows it as failing regression tests on all platforms.\\n>> Possibly a conflict with some recent commit?\\n\\n> I can't see this on cfbot - either I don't know how to use it\\n> properly, which is quite possible, or the results aren't showing up\\n> because of the close of the July CommitFest.\\n\\nI think the latter --- the cfbot thinks the July CF is no longer relevant,\\nbut Jacob hasn't yet moved your patches forward. You could wait for\\nhim to do that, or do it yourself.\\n\\n(Probably our nonexistent SOP manual for CFMs ought to say \\\"don't\\nclose the old CF till you've moved everything forward\\\".)\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 01 Aug 2022 13:38:35 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Mon, Aug 1, 2022 at 1:38 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> I think the latter --- the cfbot thinks the July CF is no longer relevant,\\n> but Jacob hasn't yet moved your patches forward. You could wait for\\n> him to do that, or do it yourself.\\n\\nDone. New patches attached.\\n\\nChanges in v4, for 0001:\\n\\n- Typo fix.\\n- Whitespace fixes.\\n\\nChanges in v4, for 0002:\\n\\n- Remove \\\"XXX sketchy\\\" comment because the thing in question turns out\\nnot to be sketchy. It has to do with the behavior of ALTER GROUP ..\\nDROP USER and, having investigated the situation, I think the\\nmessaging is clear enough.\\n- But just to be sure, add a note to the ALTER GROUP documentation to\\ntry to make things more clear.\\n- Wording fixes to the \\\"If <literal>GRANTED BY</literal> is\\nspecified...\\\" paragraph of the GRANT documentation. I reworded this a\\nbit more extensively than what Stephen proposed. Hopefully this is\\nclearer now, or at least no longer missing any words.\\n- Change message to \\\"admin option cannot be granted back to your own\\ngrantor\\\". The choice of message is intended to be consistent with the\\nexisting message \\\"grant options cannot be granted back to your own\\ngrantor,\\\" but while there's one grant option per privilege, there's\\nonly one admin option. Stephen suggested adopting a message that I had\\nmeant to take out of the version I posted, but which ended up\\nsurviving in one place, \\\"grants with admin options cannot be\\ncircular\\\". And we could still decide to do something like that, but my\\nenthusiasm for that direction was considerably reduced when I realized\\nthat \\\"circular\\\" is not very clear at all, because there are multiple\\nkinds of circularities (role-member, member-grantor).\\n- Fix comment to say DROP_RESTRICT instead of DROP_RECURSE.\\n- Make the comment for check_role_grantor() longer so that it can\\nbetter explain itself.\\n- Rephrase part of the header comment for initialize_revoke_actions()\\nbecause Stephen found it awkward.\\n- Whitespace fixes.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 1 Aug 2022 15:51:03 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Mon, Aug 1, 2022 at 10:38 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > I can't see this on cfbot - either I don't know how to use it\\n> > properly, which is quite possible, or the results aren't showing up\\n> > because of the close of the July CommitFest.\\n>\\n> I think the latter --- the cfbot thinks the July CF is no longer relevant,\\n> but Jacob hasn't yet moved your patches forward. You could wait for\\n> him to do that, or do it yourself.\\n>\\n> (Probably our nonexistent SOP manual for CFMs ought to say \\\"don't\\n> close the old CF till you've moved everything forward\\\".)\\n\\nSorry about that. I've made a note to add this to the manual later.\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Aug 2022 10:48:53 -0700\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Mon, Aug 1, 2022 at 3:51 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Mon, Aug 1, 2022 at 1:38 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> >> I think the latter --- the cfbot thinks the July CF is no longer relevant,\\n> > but Jacob hasn't yet moved your patches forward. You could wait for\\n> > him to do that, or do it yourself.\\n>\\n> Done. New patches attached.\\n\\nWell, CI isn't happy with this, and for good reason:\\n\\n ALTER GROUP regress_priv_group2 ADD USER regress_priv_user2; -- duplicate\\n-NOTICE: role \\\"regress_priv_user2\\\" has already been granted\\nmembership in role \\\"regress_priv_group2\\\" by role \\\"rhaas\\\"\\n+NOTICE: role \\\"regress_priv_user2\\\" has already been granted\\nmembership in role \\\"regress_priv_group2\\\" by role \\\"postgres\\\"\\n\\nThe problem here is that I revised the error message to include the\\nname of the grantor, since that's now a part of the identity of the\\ngrant. It would be misleading to say, as we did previously...\\n\\nNOTICE: role \\\"regress_priv_user2\\\" is already a member of role\\n\\\"regress_priv_group2\\\"\\n\\n...because them being in the group isn't relevant so much as them\\nbeing in the group by means of the same grantor. However, I suspect\\nthat I can't persuade all of you that we should hard-code the name of\\nthe bootstrap superuser as \\\"rhaas\\\", so this test case needs some\\nalteration. I found, however, that the original intent of the test\\ncase couldn't be preserved with the patch as written, because when you\\ngrant membership in one role to another role as the superuser or a\\nCREATEROLE user, the grant is attributed to the bootstrap superuser,\\nwhose name is variable, as this test failure shows. Therefore, to fix\\nthe test, I needed to use ALTER GROUP as a non-CREATEROLE user, some\\nuser created as part of the test, for the results to be stable. But\\nthat was impossible, because even though \\\"GRANT user_name TO\\ngroup_name\\\" requires *either* CREATEROLE *or* ADMIN OPTION on the\\ngroup, the equivalent command \\\"ALTER GROUP group_name ADD USER\\nuser_name\\\" requires specifically CREATEROLE.\\n\\nI debated whether to fix that inconsistency or just remove this test\\ncase and eventually came down on the side of fixing the inconsistency,\\nso the attached version does it that way.\\n\\n--\\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 10 Aug 2022 16:28:45 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Wed, Aug 10, 2022 at 4:28 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> Well, CI isn't happy with this, and for good reason:\\n\\nCI is happier with this version, so I've committed 0001. If no major\\nproblems emerge, I'll proceed with 0002 as well.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Aug 2022 13:26:08 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Thu, Aug 18, 2022 at 1:26 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Wed, Aug 10, 2022 at 4:28 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > Well, CI isn't happy with this, and for good reason:\\n>\\n> CI is happier with this version, so I've committed 0001. If no major\\n> problems emerge, I'll proceed with 0002 as well.\\n\\nDone.\\n\\n--\\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Aug 2022 11:47:00 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Mon, 2022-08-22 at 11:47 -0400, Robert Haas wrote:\\n> On Thu, Aug 18, 2022 at 1:26 PM Robert Haas <robertmhaas@gmail.com>\\n> wrote:\\n> > On Wed, Aug 10, 2022 at 4:28 PM Robert Haas <robertmhaas@gmail.com>\\n> > wrote:\\n> > > Well, CI isn't happy with this, and for good reason:\\n> > \\n> > CI is happier with this version, so I've committed 0001. If no\\n> > major\\n> > problems emerge, I'll proceed with 0002 as well.\\n> \\n> Done.\\n\\nIt's still on the CF, so I took a look.\\n\\nThere's still some weirdness around superusers:\\n\\n1. \\\"GRANTED BY current_user\\\" differs from not specifying \\\"GRANTED BY\\\"\\nat all.\\n\\n a. With GRANTED BY current_user, weird because current_user is a\\nsuperuser:\\n\\n CREATE USER su1 SUPERUSER;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n \\\\c - su1\\n GRANT u2 TO u1 GRANTED BY current_user;\\n ERROR: grantor must have ADMIN OPTION on \\\"u2\\\"\\n\\n b. Without GRANTED BY:\\n\\n CREATE USER su1 SUPERUSER;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n \\\\c - su1\\n GRANT u2 TO u1;\\n -- grantor is bootstrap superuser\\n\\n2. Grantor can depend on the path to get there:\\n\\n a. Already superuser:\\n\\n CREATE USER su1 SUPERUSER;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n GRANT u2 TO su1 WITH ADMIN OPTION;\\n \\\\c - su1\\n GRANT u2 TO u1;\\n -- grantor is bootstrap superuser\\n\\n b. Becomes superuser after GRANT:\\n\\n CREATE USER su1;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n GRANT u2 TO su1 WITH ADMIN OPTION;\\n \\\\c - su1\\n GRANT u2 TO u1;\\n \\\\c - bootstrap_superuser\\n ALTER ROLE su1 SUPERUSER;\\n -- grantor is su1\\n\\n3. Another case where \\\"GRANTED BY current_user\\\" differs from no\\n\\\"GRANTED BY\\\" at all, with slightly different consequences:\\n\\n a. GRANTED BY current_user, throws error:\\n\\n CREATE USER su1 SUPERUSER;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n GRANT u2 TO su1 WITH ADMIN OPTION;\\n \\\\c - su1\\n GRANT u2 TO u1 GRANTED BY current_user;\\n -- grantor is su1\\n \\\\c - bootstrap_superuser\\n REVOKE ADMIN OPTION FOR u2 FROM su1;\\n ERROR: dependent privileges exist\\n\\n b. No GRANTED BY, no error:\\n\\n CREATE USER su1 SUPERUSER;\\n CREATE ROLE u1;\\n CREATE ROLE u2;\\n GRANT u2 TO su1 WITH ADMIN OPTION;\\n \\\\c - su1\\n GRANT u2 TO u1;\\n -- grantor is bootstrap superuser\\n \\\\c - boostrap_superuser\\n REVOKE ADMIN OPTION FOR u2 FROM su1;\\n\\n\\n\\nWe seem to be trying very hard to satisfy two things that seem\\nimpossible to satisfy:\\n\\n i. \\\"ALTER ROLE ... NOSUPERUSER\\\" must always succeed, and probably\\nexecute quickly, too.\\n ii. We want to maintain catalog invariants that are based, in part,\\non roles having superuser privileges or not.\\n\\nThe hacks we are using to try to make this work are just that: hacks.\\nAnd it's all to satisfy a fairly rare case: removing superuser\\nprivileges and expecting the catalogs to be consistent.\\n\\nI think we'd be better off without these hacks. I'm not sure exactly\\nhow, but the benefit doesn't seem to be worth the cost. Some\\nalternative ideas:\\n\\n * Have a \\\"safe\\\" version of removing superuser that can error or\\ncascade, and an \\\"unsafe\\\" version that always succeeds but might leave\\ninconsistent catalogs.\\n * Ignore the problems with removing superuser, but issue a WARNING\\n * Superusers would auto-grant themselves the privileges that a normal\\nuser would need to do something before doing it. For instance, if a\\nsuperuser did \\\"GRANT u2 TO u1\\\", it would first automatically issue a\\n\\\"GRANT u2 TO current_user WITH ADMIN OPTION GRANTED BY\\nbootstrap_superuser\\\", then do the grant normally. If the superuser\\nprivileges are removed, then the catalogs would still be consistent.\\nThis is a new idea and I didn't think it through very carefully, but\\nmight be an interesting approach.\\n\\nAlso, it would be nice to have REASSIGN OWNED work with grants, perhaps\\nby adding a \\\"WITH[OUT] GRANT\\\" or something.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 01 Sep 2022 13:34:06 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Thanks for having a look.\\n\\nOn Thu, Sep 1, 2022 at 4:34 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> There's still some weirdness around superusers:\\n>\\n> 1. \\\"GRANTED BY current_user\\\" differs from not specifying \\\"GRANTED BY\\\"\\n> at all.\\n\\nYes. I figured that, when GRANTED BY is not specified, it is OK to\\ninfer a valid grantor, but if it is specified, it does not seem right\\nto infer a grantor other than the one specified. Admittedly, this case\\nis without precedent elsewhere in the system, because nobody has made\\nGRANTED BY work for other object types, outside of trivial cases.\\nStill, it seems like the right behavior to me.\\n\\n> 2. Grantor can depend on the path to get there:\\n>\\n> a. Already superuser:\\n>\\n> CREATE USER su1 SUPERUSER;\\n> CREATE ROLE u1;\\n> CREATE ROLE u2;\\n> GRANT u2 TO su1 WITH ADMIN OPTION;\\n> \\\\c - su1\\n> GRANT u2 TO u1;\\n> -- grantor is bootstrap superuser\\n>\\n> b. Becomes superuser after GRANT:\\n>\\n> CREATE USER su1;\\n> CREATE ROLE u1;\\n> CREATE ROLE u2;\\n> GRANT u2 TO su1 WITH ADMIN OPTION;\\n> \\\\c - su1\\n> GRANT u2 TO u1;\\n> \\\\c - bootstrap_superuser\\n> ALTER ROLE su1 SUPERUSER;\\n> -- grantor is su1\\n\\nThis also seems correct to me, and here I believe you could construct\\nsimilar examples with other object types. We infer the grantor based\\non the state of the system at the time the grant was performed. We\\ncan't change our mind later even if things have changed that would\\ncause us to make a different inference. In the case of a table, for\\nexample, consider:\\n\\ncreate role p1;\\ncreate role p2;\\ncreate role a;\\ncreate table t1 (a int);\\ncreate role b;\\ngrant select on table t1 to p1 with grant option;\\ngrant select on table t1 to p2 with grant option;\\ngrant p1 to a;\\nset session authorization a;\\ngrant select on table t1 to b;\\n\\nAt this point, b has SELECT permission on table t1 and the grantor of\\nrecord is p1. But if you had done \\\"GRANT p2 TO a\\\" then the grantor of\\nrecord would be p2 rather than p1. And you can still \\\"REVOKE p1 FROM\\na;\\\" and then \\\"GRANT p2 to a;\\\". As in your example, doing so won't\\nchange the grantor recorded for the grant already made.\\n\\n> 3. Another case where \\\"GRANTED BY current_user\\\" differs from no\\n> \\\"GRANTED BY\\\" at all, with slightly different consequences:\\n\\nIt's extremely difficult for me to imagine what other behavior would\\nbe sane here. In this example, the inferred best grantor is different\\nfrom the current user, so forcing the grantor to be the current user\\nchanges the behavior. There are only two ways that anything different\\ncan happen: either we'd have to change the algorithm for inferring the\\nbest grantor, or we'd have to be willing to disregard the user's\\nexplicit specification that the grantor be the current user rather\\nthan somebody else.\\n\\nAs to the first, the algorithm being used to select the best grantor\\nhere is analogous to the one we use for privileges on other object\\ntypes, such as tables, namely, we prefer to create a grant that is not\\ndependent on some other grant, rather than one that is. Maybe that's\\nthe best policy and maybe it isn't, but I can't see it being\\nreasonable to have one policy for grants on tables, functions, etc.\\nand another policy for grants on roles.\\n\\nAs to the second, this is somewhat similar to the case you already\\nraised in your example #1. However, in that case, the\\nexplicitly-specified grantor wasn't valid, so the grant failed. I\\ndon't think it's right to allow inference in the presence of an\\nexplicit specification, but if the consensus was that we really ought\\nto make that case succeed, I suppose we could. Here, however, the\\nexplicitly-specified grantor *is a legal grantor*. I think it would be\\nextremely surprising if we just ignored that and selected some other\\nvalid grantor instead.\\n\\n> We seem to be trying very hard to satisfy two things that seem\\n> impossible to satisfy:\\n>\\n> i. \\\"ALTER ROLE ... NOSUPERUSER\\\" must always succeed, and probably\\n> execute quickly, too.\\n> ii. We want to maintain catalog invariants that are based, in part,\\n> on roles having superuser privileges or not.\\n>\\n> The hacks we are using to try to make this work are just that: hacks.\\n> And it's all to satisfy a fairly rare case: removing superuser\\n> privileges and expecting the catalogs to be consistent.\\n\\nI guess I don't really agree with that view of it. The primary purpose\\nof the patch was to make the handing of role grants consistent with\\nthe handling of grants on other object types. I did extend the\\nexisting functionality, because the GRANTED BY <whoever> clause works\\nfor role grants and does not work for other grants. However, that also\\nworked for role grants before these patches, whereas it's never worked\\nfor other object types. So I chose to restrict that functionality as\\nlittle as possible, and basically make it work, rather than removing\\nit completely, which would have been the most consistent with what we\\ndo elsewhere.\\n\\nWhen you view this in the context of how other types of grants work,\\nALTER ROLE ... NOSUPERUSER isn't as much of a special case. Just as we\\nwant ALTER ROLE ... NOSUPERUSER to succeed quickly, we also insist\\nthat REVOKE role1 FROM role2 to succeed quickly. It isn't allowed to\\nfail due to the existence of dependent privileges, because there\\naren't allowed to be any dependent privileges. GRANT role1 TO role2\\ndoesn't really give role2 the privileges of role1; what it does is\\nallow role2 to act on behalf of role1. Similarly, ALTER ROLE ...\\nSUPERUSER lets the target role act on behalf of any user at all,\\nincluding the bootstrap superuser. In either case, actions are\\nattributed to the user on behalf of whom they were performed, not the\\nuser who actually typed the command.\\n\\nAs another example, consider a superuser (the bootstrap superuser or\\nany other one) who executes GRANT SELECT ON some_random_table TO\\nsome_random_user. Who will be recorded as the grantor? The answer is\\nthat the table owner will be recorded as the grantor, because the\\ntable owner is the one who actually has permission to perform the\\noperation. The superuser doesn't, except by virtue of their ability to\\nact on behalf of any other user in the system. In most cases, that's\\njust an academic distinction, because the question is only whether or\\nnot the operation can be performed, and not who has to perform it. But\\ngrants are different: it matters who does it, and when someone uses\\nsuperuser powers or other special privileges to perform an operation,\\nwe have to ask on whose behalf they are acting.\\n\\n> I think we'd be better off without these hacks. I'm not sure exactly\\n> how, but the benefit doesn't seem to be worth the cost. Some\\n> alternative ideas:\\n>\\n> * Have a \\\"safe\\\" version of removing superuser that can error or\\n> cascade, and an \\\"unsafe\\\" version that always succeeds but might leave\\n> inconsistent catalogs.\\n> * Ignore the problems with removing superuser, but issue a WARNING\\n\\nI don't like either of these. I think the fact that we have strong\\nintegrity constraints around who can be recorded as the grantor of a\\nprivilege is a good thing, and, again, the purpose of this patch was\\nto bring role grants up to the level of other parts of the system.\\n\\n> * Superusers would auto-grant themselves the privileges that a normal\\n> user would need to do something before doing it. For instance, if a\\n> superuser did \\\"GRANT u2 TO u1\\\", it would first automatically issue a\\n> \\\"GRANT u2 TO current_user WITH ADMIN OPTION GRANTED BY\\n> bootstrap_superuser\\\", then do the grant normally. If the superuser\\n> privileges are removed, then the catalogs would still be consistent.\\n> This is a new idea and I didn't think it through very carefully, but\\n> might be an interesting approach.\\n\\nIf we did this, we ought to do it for all object types, so that if a\\nsuperuser grants privileges on a table they don't own, they implicitly\\ngrant themselves those privileges with grant option and then grant\\nthem to the requested recipient. I doubt that behavior change would be\\npopular, and I bet somebody would complain about the SQL standard or\\nsomething, but it seems more theoretically sound than the previous two\\nideas, because it doesn't just throw the idea of integrity constraints\\nout the window.\\n\\n> Also, it would be nice to have REASSIGN OWNED work with grants, perhaps\\n> by adding a \\\"WITH[OUT] GRANT\\\" or something.\\n\\nI thought about this, too. It's a bit tricky. Right now, DROP OWNED\\ndrops grants, but REASSIGN OWNED doesn't change their owner. On first\\nglance, this seems inconsistent: either grants are a kind of object\\nand DROP OWNED and REASSIGN OWNED ought to apply to them like anything\\nelse, or they are not a type of object and neither command should\\ntouch them. However, there's a pretty significant difference between\\n(1) a table and (2) a grant of privileges on a table. Ownership on the\\ntable itself can be freely changed to any role in the system at any\\ntime. We rewrite the table's ACL on the fly to preserve the invariants\\nabout who can be listed as the grantor. But for the grant of\\nprivileges on the table, we can't freely change the grantor of record\\nto an arbitrary user at any time: the set of valid grantors is\\nconstrained.\\n\\nWhat might be useful is a command that says \\\"OK, for every existing\\ngrant that is attributed to user A, change the recorded grantor to\\nuser B, if that's allowable, for the others, do nothing\\\". Or maybe\\nthere's some possible idea where we try to somehow make B into a valid\\ngrantor, but it's not clear to me what the algorithm would be.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 2 Sep 2022 09:30:24 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, 2022-09-02 at 09:30 -0400, Robert Haas wrote:\\n> Thanks for having a look.\\n\\nThanks for doing the work.\\n\\n> Yes. I figured that, when GRANTED BY is not specified, it is OK to\\n> infer a valid grantor\\n\\nThe spec is clear that the grantor should be either the current user or\\nthe current role. We also have a concept of INHERIT, which allows us to\\nchoose a role we're a member of if the current one does not suffice.\\n\\nBut to choose a different role (the bootstrap superuser) even when the\\ncurrent (super) user role *does* suffice seems like an outright\\nviolation of both the spec and the principle of least surprise.\\n> \\n\\n> set session authorization a;\\n> grant select on table t1 to b;\\n> \\n> At this point, b has SELECT permission on table t1 and the grantor of\\n> record is p1\\n\\nThat's because \\\"a\\\" does not have permision to grant select on t1, so\\nINHERIT kicks in to implicitly \\\"SET ROLE p1\\\". What keeps INHERIT sane\\nis that it only kicks in when required (i.e. it would otherwise result\\nin failure).\\n\\nBut in the case I raised, the current user is an entirely valid\\ngrantor, so it doesn't make sense to me to infer a different grantor.\\n\\n> \\n\\n> As to the first, the algorithm being used to select the best grantor\\n> here is analogous to the one we use for privileges on other object\\n> types, such as tables, namely, we prefer to create a grant that is\\n> not\\n> dependent on some other grant, rather than one that is.\\n\\nI don't quite follow. It seems like we're conflating a policy based on\\nINHERIT with the policy around grants by superusers.\\n\\nIn the case of role membership and INHERIT, our current behavior seems\\nwise (and closer to the standard): to prefer a grantor that is closer\\nto the current user/role, and therefore less dependent on other grants.\\n\\nBut for the new policy around superusers, the current superuser is a\\ncompletely valid grantor, and we instead preferring the bootstrap\\nsuperuser. That doesn't seem consistent or wise to me.\\n\\n\\n> \\n> The primary purpose\\n> of the patch was to make the handing of role grants consistent with\\n> the handling of grants on other object types.\\n\\nI certainly don't want to pin every weird thing about our privilege\\nsystem on you just because you're the last one to touch it. But your\\nchanges did extend the behavior, and create some new analogous\\nbehavior, so it seems like a reasonable time to discuss whether those\\nextensions are in the right direction.\\n\\n> When you view this in the context of how other types of grants work,\\n> ALTER ROLE ... NOSUPERUSER isn't as much of a special case. Just as\\n> we\\n> want ALTER ROLE ... NOSUPERUSER to succeed quickly, we also insist\\n> that REVOKE role1 FROM role2 to succeed quickly. It isn't allowed to\\n> fail due to the existence of dependent privileges, because there\\n> aren't allowed to be any dependent privileges.\\n\\n create user u1;\\n create user u2;\\n create user u3;\\n grant u2 to u1 with admin option;\\n \\\\c - u1\\n grant u2 to u3;\\n \\\\c - bootstrap_superuser\\n revoke u2 from u1;\\n ERROR: dependent privileges exist\\n\\n> But\\n> grants are different: it matters who does it, and when someone uses\\n> superuser powers or other special privileges to perform an operation,\\n> we have to ask on whose behalf they are acting.\\n\\nIf superusers merely act on behalf of others, then:\\n\\n 1. Why can the bootstrap superuser be a grantor?\\n 2. Why can non-bootstrap superusers specify themselves in GRANTED BY\\nif they are not suitable grantors?\\n\\n> \\n> I think the fact that we have strong\\n> integrity constraints around who can be recorded as the grantor of a\\n> privilege is a good thing, and, again, the purpose of this patch was\\n> to bring role grants up to the level of other parts of the system.\\n\\nI like integrity constriants, too. But it feels like we're recording\\nthe wrong information (losing the actual grantor) because it's easier\\nto keep it \\\"consistent\\\", which doesn't necessarily seem like a win.\\n\\nAnd the whole reason we are jumping through all of these hoops is\\nbecause we want to allow the removal of superuser privileges quickly\\nwithout the possibility of failure. In other words, we don't have time\\nto do the work of cascading to dependent objects, or erroring when we\\nfind them. I'm not entirely sure I agree that's a hard requirement,\\nbecause dropping a superuser can fail. But even if it is a requirement,\\nare we even meeting it if we preserve the grants that the former\\nsuperuser created? I'd like to know more about this requirement, and\\nwhether we are still meeting it, and whether there are alternatives.\\n\\nIt just feels like this edge case requirement about dropping superuser\\nprivileges is driving the whole design, and that feels wrong to me.\\n\\n> > * Superusers would auto-grant themselves the privileges that a\\n> > normal\\n> > user would need to do something before doing it. For instance, if a\\n> > superuser did \\\"GRANT u2 TO u1\\\", it would first automatically issue\\n> > a\\n> > \\\"GRANT u2 TO current_user WITH ADMIN OPTION GRANTED BY\\n> > bootstrap_superuser\\\", then do the grant normally. \\n\\n...\\n\\n> it seems more theoretically sound than the previous two\\n> ideas, because it doesn't just throw the idea of integrity\\n> constraints\\n> out the window.\\n\\nPerhaps it's worth considering further. Would be a separate patch, of\\ncourse.\\n\\n> > Also, it would be nice to have REASSIGN OWNED work with grants,\\n> > perhaps\\n> > by adding a \\\"WITH[OUT] GRANT\\\" or something.\\n\\n...\\n\\n> What might be useful is a command that says \\\"OK, for every existing\\n> grant that is attributed to user A, change the recorded grantor to\\n> user B, if that's allowable, for the others, do nothing\\\". Or maybe\\n> there's some possible idea where we try to somehow make B into a\\n> valid\\n> grantor, but it's not clear to me what the algorithm would be.\\n\\nI was thinking that if the new grantor is not allowable, and \\\"WITH\\nGRANT\\\" (or whatever) was specified, then it would throw an error.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 02 Sep 2022 15:01:10 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Fri, Sep 2, 2022 at 6:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > Yes. I figured that, when GRANTED BY is not specified, it is OK to\\n> > infer a valid grantor\\n>\\n> The spec is clear that the grantor should be either the current user or\\n> the current role. We also have a concept of INHERIT, which allows us to\\n> choose a role we're a member of if the current one does not suffice.\\n>\\n> But to choose a different role (the bootstrap superuser) even when the\\n> current (super) user role *does* suffice seems like an outright\\n> violation of both the spec and the principle of least surprise.\\n\\nI don't think that the current superuser role suffices. For non-role\\nobjects, privileges originate in the table owner and can then be\\ngranted to others. Roles don't have an explicit owner, so I treated\\nthe bootstrap superuser as the implicit owner of every role. Perhaps\\nthere is some other way we could go here - e.g. it's been proposed by\\nmultiple people that maybe roles should have owners - but I do not\\nthink it is viable to regard the owner of a role as being anyone who\\nhappens to be a superuser right at the moment. To some extent that's\\nrelated to your concern about whether ALTER USER .. NOSUPERUSER should\\nbe fast and immune to failure, but I also think that it is a good idea\\nto have all of the privileges originating from a single owner. That\\nensures, for example, that anyone who can act as the object owner can\\nrevoke any privilege, which wouldn't necessarily be true if the object\\nhad multiple owners. Now if all of the owners are themselves\\nsuperusers who all have the power to become any of the other owners\\nthen perhaps it wouldn't end up mattering too much, but it doesn't\\nseem like a good idea to rely on that. In fact, part of my goal here\\nis to get to a world where there's less need to rely on superuser\\npowers to do system administration. I also just think it's less\\nconfusing if objects have single owners rather than nebulous groups of\\nowners.\\n\\n> > set session authorization a;\\n> > grant select on table t1 to b;\\n> >\\n> > At this point, b has SELECT permission on table t1 and the grantor of\\n> > record is p1\\n>\\n> That's because \\\"a\\\" does not have permision to grant select on t1, so\\n> INHERIT kicks in to implicitly \\\"SET ROLE p1\\\". What keeps INHERIT sane\\n> is that it only kicks in when required (i.e. it would otherwise result\\n> in failure).\\n>\\n> But in the case I raised, the current user is an entirely valid\\n> grantor, so it doesn't make sense to me to infer a different grantor.\\n\\nSee above, but also, see the first stanza of select_best_grantor(). If\\nalice is a table owner, and grants permissions to bob WITH GRANT\\nOPTION, and bob is a superuser and grants permissions on the table,\\nthe grantor will be alice, not bob.\\n\\n> > As to the first, the algorithm being used to select the best grantor\\n> > here is analogous to the one we use for privileges on other object\\n> > types, such as tables, namely, we prefer to create a grant that is\\n> > not\\n> > dependent on some other grant, rather than one that is.\\n>\\n> I don't quite follow. It seems like we're conflating a policy based on\\n> INHERIT with the policy around grants by superusers.\\n>\\n> In the case of role membership and INHERIT, our current behavior seems\\n> wise (and closer to the standard): to prefer a grantor that is closer\\n> to the current user/role, and therefore less dependent on other grants.\\n>\\n> But for the new policy around superusers, the current superuser is a\\n> completely valid grantor, and we instead preferring the bootstrap\\n> superuser. That doesn't seem consistent or wise to me.\\n\\nI hope that the above comments on treating the bootstrap superuser as\\nthe object owner explain why it works this way.\\n\\n> I certainly don't want to pin every weird thing about our privilege\\n> system on you just because you're the last one to touch it. But your\\n> changes did extend the behavior, and create some new analogous\\n> behavior, so it seems like a reasonable time to discuss whether those\\n> extensions are in the right direction.\\n\\nSure.\\n\\n> > When you view this in the context of how other types of grants work,\\n> > ALTER ROLE ... NOSUPERUSER isn't as much of a special case. Just as\\n> > we\\n> > want ALTER ROLE ... NOSUPERUSER to succeed quickly, we also insist\\n> > that REVOKE role1 FROM role2 to succeed quickly. It isn't allowed to\\n> > fail due to the existence of dependent privileges, because there\\n> > aren't allowed to be any dependent privileges.\\n>\\n> create user u1;\\n> create user u2;\\n> create user u3;\\n> grant u2 to u1 with admin option;\\n> \\\\c - u1\\n> grant u2 to u3;\\n> \\\\c - bootstrap_superuser\\n> revoke u2 from u1;\\n> ERROR: dependent privileges exist\\n\\nHmm, I stand corrected. I was thinking of a case in which the grant\\nwas used to perform an action on behalf of an inherited role. Here the\\ngrant from u2 to u3 is performed as u1 and attributed to u1.\\n\\n> And the whole reason we are jumping through all of these hoops is\\n> because we want to allow the removal of superuser privileges quickly\\n> without the possibility of failure. In other words, we don't have time\\n> to do the work of cascading to dependent objects, or erroring when we\\n> find them. I'm not entirely sure I agree that's a hard requirement,\\n> because dropping a superuser can fail. But even if it is a requirement,\\n> are we even meeting it if we preserve the grants that the former\\n> superuser created? I'd like to know more about this requirement, and\\n> whether we are still meeting it, and whether there are alternatives.\\n>\\n> It just feels like this edge case requirement about dropping superuser\\n> privileges is driving the whole design, and that feels wrong to me.\\n\\nI'm struggling to figure out how to reply to this exactly. I do agree\\nthat the way ALTER ROLE .. [NO]SUPERUSER thing works is something of a\\nwart, and if we were designing SQL from scratch all over again in\\n2022, I think it's reasonably likely that a lot of things would end up\\nworking quite a bit differently than they actually do. But, at the\\nsame time, it also seems to me that (1) the way ALTER ROLE ..\\n[NO]SUPERUSER works is pretty firmly entrenched at this point and we\\ncan't easily get away with changing it; (2) I don't really see an easy\\nway of changing it that wouldn't cause more problems than it solves;\\nand (3) it all seems relatively unrelated to this patch.\\n\\nLike, the logic to infer the grantor in check_role_grantor() and\\nselect_best_admin() is intended to be, and as far as I know actually\\nis, an exact clone of the logic in select_best_grantor(). It is\\ndifferent only in that we regard the bootstrap superuser as the object\\nowner because there is no other owner stored in the catalogs; and in\\nthat we check CREATEROLE permission rather than SUPERUSER permission.\\nEverything else is the same. To be unhappy with the patch, you have to\\nthink either that (1) treating the bootstrap superuser as the owner of\\nevery role is the wrong idea or (2) that role grants should not choose\\nan implicit grantor in the same way that other types of grants do or\\n(3) that the code has a bug.\\n\\nIf you don't think any of those things but believe that the way we've\\nmade superusers interact with the grant system is lame in general, I\\nsomewhat agree, but if we came up with some new paradigm for how it\\nshould work, we'd have to explain why it was sufficiently better than\\nthe status quo to justify breaking backward compatibility, and I think\\nthat would be a hard argument to make. The current system feels kind\\nof old-fashioned and awkward, but it's self-consistent on its terms\\nand I bet a lot of people are relying on it to keep working. And I\\nthink if we were going to replace it with something that feels fresh\\nand modern, focusing on the behavior of ALTER ROLE .. [NO]SUPERUSER\\nwould be the wrong place to start. That, to me, seems like it's a\\n*mostly* a consequence of much broader design choices, like:\\n\\n- Having hard-coded superuser checks in many places instead of making\\neverything a capability.\\n- Having potentially any number of superusers, instead of just one root user.\\n- Having granted privileges depend on the grantor continuing to hold\\nthe granted privilege, instead of existing independently.\\n\\nIf I were designing a privilege system for a new piece of software\\nthat didn't need to comply with the SQL standard, I think I'd throw at\\nleast some and maybe all of those things right out the window. But I\\ndesigned a system that had to work within that set of assumptions, I\\nthink I'd make it work pretty much the way it actually does.\\n\\n> > What might be useful is a command that says \\\"OK, for every existing\\n> > grant that is attributed to user A, change the recorded grantor to\\n> > user B, if that's allowable, for the others, do nothing\\\". Or maybe\\n> > there's some possible idea where we try to somehow make B into a\\n> > valid\\n> > grantor, but it's not clear to me what the algorithm would be.\\n>\\n> I was thinking that if the new grantor is not allowable, and \\\"WITH\\n> GRANT\\\" (or whatever) was specified, then it would throw an error.\\n\\nThat could be done too, but then every grant attributed to the target\\nrole would have to be validly reattributable to the same new grantor.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 6 Sep 2022 13:15:24 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Tue, 2022-09-06 at 13:15 -0400, Robert Haas wrote:\\n\\n\\n> Like, the logic to infer the grantor in check_role_grantor() and\\n> select_best_admin() is intended to be, and as far as I know actually\\n> is, an exact clone of the logic in select_best_grantor(). It is\\n> different only in that we regard the bootstrap superuser as the\\n> object\\n> owner because there is no other owner stored in the catalogs; and in\\n> that we check CREATEROLE permission rather than SUPERUSER permission.\\n\\nThere's at least one other difference: if you specify \\\"GRANTED BY su1\\\"\\nfor a table grant, it still selects the table owner as the grantor;\\nwhereas if you specify \\\"GRANTED BY su1\\\" for a role grant, it selects\\n\\\"su1\\\".\\n\\n grant all privileges on schema public to public;\\n create user su1 superuser;\\n create user u1;\\n create user u2;\\n create user aa;\\n grant u2 to su1 with admin option;\\n \\\\c - aa\\n create table t_aa(i int);\\n grant all privileges on t_aa to su1 with grant option;\\n \\\\c - su1\\n grant select on t_aa to u1 granted by su1;\\n -- grantor aa\\n select relname, relacl from pg_class where relname='t_aa';\\n grant u2 to u1 granted by su1; -- grantor su1\\n -- grantor su1\\n select grantor::regrole from pg_auth_members\\n where member='u1'::regrole;\\n\\n[ If you run the same example but where su1 is not a superuser, then\\nboth select \\\"su1\\\" as the grantor because that's the only valid grantor\\nthat can be inferred. ]\\n\\nNow that I understand the underlying philosophy better, and I've\\nexperimented with more cases, I propose the following grantor inference\\nbehavior which I believe is in the spirit of your changes:\\n\\n * Let the granting user be the one specified in the GRANTED BY clause\\nif it exists; otherwise the current user. In other words, omitting\\nGRANTED BY is the same as specifying \\\"GRANTED BY current_user\\\".\\n * If the granting user has privileges to be the grantor (ADMIN OPTION\\nfor roles, GRANT OPTION for other objects) then the granting user is\\nthe grantor.\\n * Else if the granting user inherits from a user with the privileges\\nto be the grantor, then it selects a role with the fewest inheritance\\nhops as the grantor.\\n * Else if the current user is any superuser:\\n - If the grant is a role grant, it selects the bootstrap superuser\\nas the grantor.\\n - Else the object owner is the grantor.\\n * Else error (or if an error would break important backwards\\ncompatibility, silently make it work like before or perhaps issue a\\nWARNING).\\n\\nIn other words, try to issue the grant normally if at all possible, and\\nplay the superuser card as a last resort. I believe that will lead to\\nthe fewest surprising cases, and make them easiest to explain, because\\nsuperuser-ness doesn't influence the outcome in as many cases.\\n\\nIt cements the idea that the bootstrap superuser is the \\\"real\\\"\\nsuperuser, and must always remain so, and that all other superusers are\\ntemporary stand-ins (kind of but not quite the same as inheritance).\\nAnd it leaves the ugliness that we lose the information about the\\n\\\"real\\\" grantor when we play the superuser card, but, as I say above,\\nthat would be a last resort.\\n\\nThe proposal would be a slight behavior change from v15 in the\\nfollowing case:\\n\\n grant all privileges on schema public to public;\\n create user su1 superuser;\\n create user u1;\\n create user aa;\\n \\\\c - aa\\n create table t_aa(i int);\\n grant all privileges on t_aa to su1 with grant option;\\n \\\\c - su1\\n grant select on t_aa to u1 granted by su1;\\n -- grantor \\\"aa\\\" in v15, grantor \\\"su1\\\" after my proposal\\n select relname, relacl from pg_class where relname='t_aa';\\n\\nAnother change in behavior would be that the bootstrap superuser could\\nbe the grantor for table privileges, if the bootstrap superuser has\\nWITH GRANT OPTION privileges.\\n\\nBut those seems minor to me.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 06 Sep 2022 16:26:12 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Tue, 2022-09-06 at 16:26 -0700, Jeff Davis wrote:\\n> In other words, omitting\\n> GRANTED BY is the same as specifying \\\"GRANTED BY current_user\\\".\\n\\nLet me correct this thinko to distinguish between specifying GRANTED BY\\nand not:\\n\\n * Let the granting user be the one specified in the GRANTED BY clause\\nif it exists; otherwise the current user.\\n * If the granting user has privileges to be the grantor (ADMIN OPTION\\nfor roles, GRANT OPTION for other objects) then the granting user is\\nthe grantor.\\n * Else if GRANTED BY was *not* specified, infer the grantor:\\n - If the granting user inherits from a role with the privileges\\nto be the grantor, then it selects a role with the fewest inheritance\\nhops as the grantor.\\n - Else if the current user is any superuser, the grantor is the top\\n\\\"owner\\\" (bootstrap superuser for roles; object owner for other objects)\\n * Else error (or if an error would break important backwards\\ncompatibility, silently make it work like before and perhaps issue a\\nWARNING).\\n\\nThe basic idea is to use superuser privileges as a last resort in order\\nto maximize the cases that work normally (independent of superuser-\\nness).\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 06 Sep 2022 18:27:32 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Tue, Sep 6, 2022 at 7:26 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> There's at least one other difference: if you specify \\\"GRANTED BY su1\\\"\\n> for a table grant, it still selects the table owner as the grantor;\\n> whereas if you specify \\\"GRANTED BY su1\\\" for a role grant, it selects\\n> \\\"su1\\\".\\n\\nRight. Personally, I'm inclined to view that as a defect in the\\n\\\"GRANTED BY whoever\\\" implementation for other object types, and I\\nthink it should be resolved by making other object types error out if\\nthe user explicitly mentioned in the \\\"GRANTED BY\\\" clause isn't a valid\\ngrantor. It also seems possible to view it as a defect in the new\\nimplementation, and argue that inference should always be performed\\nstarting at the named user. I find that a POLA violation, but someone\\ncould disagree.\\n\\nParenthetically, I think we should also fix GRANTED BY for other\\nobject types so that it actually works, but that is a bit of headache\\nbecause it doesn't seem like that code is relying as heavily on common\\ninfrastructure as some things, so I believe it's actually a fair\\namount of work to make that happen.\\n\\n> In other words, try to issue the grant normally if at all possible, and\\n> play the superuser card as a last resort. I believe that will lead to\\n> the fewest surprising cases, and make them easiest to explain, because\\n> superuser-ness doesn't influence the outcome in as many cases.\\n\\nIt seems to me that this policy would reverse select_best_grantor()'s\\ndecision about whether we should prefer to rely on superuser\\nprivileges or on privileges actually granted to the current user. I\\nthink either behavior is defensible, but the existing precedent is to\\nprefer relying on superuser privileges. Like you, I found that a bit\\nweird when I realized that's what it was doing, but it does have some\\nadvantages. In particular, it means that the privileges granted by a\\nsuperuser don't depend on any other grants, which is something that a\\nuser might value.\\n\\nNow that is not to say that we couldn't decide that\\nselect_best_grantor() got it wrong and choose to break backward\\ncompatibility in order to fix it ... but I'm not even convinced that\\nthe alternative behavior you propose is clearly better, let alone that\\nit's enough better to justify changing things. However, I don't\\npersonally have a strong preference about it one way or the other; if\\nthere's a strong consensus to change it, so be it.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 7 Sep 2022 09:39:05 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Wed, 2022-09-07 at 09:39 -0400, Robert Haas wrote:\\n> Now that is not to say that we couldn't decide that\\n> select_best_grantor() got it wrong and choose to break backward\\n> compatibility in order to fix it ... but I'm not even convinced that\\n> the alternative behavior you propose is clearly better, let alone\\n> that\\n> it's enough better to justify changing things.\\n\\nOK. I suppose the best path forward is to just try to improve the\\nability to administer the system without relying as much on superusers,\\nwhich will allow us to safely ignore some of the weirdness caused by\\nsuperusers issuing grants.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 07 Sep 2022 07:56:28 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"On Wed, Sep 7, 2022 at 10:56 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> OK. I suppose the best path forward is to just try to improve the\\n> ability to administer the system without relying as much on superusers,\\n> which will allow us to safely ignore some of the weirdness caused by\\n> superusers issuing grants.\\n\\nYeah, and I think we might not even be that far away from making that\\nhappen. There are still a few thorny design issues to work out, I\\nbelieve, and there's also some complexity that is introduced by the\\nfact that different people want different things. For example, last\\nrelease cycle, I believed that the NOINHERIT behavior was a weird wart\\nthat probably nobody cared about. That turned out to be false, really\\nfalse.\\n\\nWhat I *personally* want most as an alternative to superuser is an\\naccount that inherits all the privileges of the other accounts that it\\nmanages, which might not be all the accounts on the system, and which\\ncan also SET ROLE to those accounts. If you're logged into such an\\naccount, you can do many of the things a superuser can do and in the\\nsame ways that a superuser can do them. For example, if you've got\\nsome pg_dump output, you could probably restore the dump using such an\\naccount and privilege restoration would work, provided that the\\nrequired accounts exist and that they're among the accounts managed by\\nyour account.\\n\\nHowever, I think that other people want different things. For example,\\nI think that Joshua Brindle mentioned wanting to have a user-creation\\nbot that should be able to make new accounts but not access them in\\nany way, and I think Stephen Frost was interested in semantics where\\nyou could make accounts and be able to SET ROLE into them but not\\ninherit their privileges. Or maybe they were both proposing the same\\nthing: not quite sure. Anyway, it will perhaps turn out to be\\nimpossible to give everybody 100% of everything they would like, but\\nI'm thinking about a few ideas that might enable us to cater to a few\\ndifferent scenarios - and I'm hopeful that it will be possible to\\npropose something in time for inclusion in v16, but my ideas aren't\\nquite well enough formulated yet to make a concrete proposal just yet,\\nand when I do make such a proposal I want to do it on a new thread for\\nbetter visibility.\\n\\nIn the meantime, I think that what has already been committed is\\nclearly a step in the right direction. The patch which is the subject\\nof this thread has basically brought the role grant code up to the\\nlevel of other object types. I don't think it's an overstatement to\\nsay that the previous state of affairs was that this feature just\\ndidn't work properly and no one had cared enough to bother fixing it.\\nThat always makes discussions about future enhancements harder. The\\npatch to add grant-level control to the INHERIT option also seems to\\nme to be a step in the right direction, since, at least IMHO, it is\\nreally hard to reason about behavior when the heritability of a\\nparticular grant is a property of the grantee rather than something\\nwhich can be controlled by the grantor, or the system. If we can reach\\nagreement on some of the other things that I have proposed,\\nspecifically sorting out the issues under discussion on the\\n\\\"has_privs_of_role vs. is_member_of_role, redux\\\" thread and adding the\\nnew capability discussed on the \\\"allowing for control over SET ROLE\\\"\\nthread, I think will be a further, useful step.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 7 Sep 2022 13:00:39 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Thu, Aug 18, 2022 at 1:26 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>> CI is happier with this version, so I've committed 0001. If no major\\n>> problems emerge, I'll proceed with 0002 as well.\\n\\n> Done.\\n\\nShouldn't the CF entry [1] be closed as committed?\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://commitfest.postgresql.org/39/3745/\\n\\n\\n\",\n \"msg_date\": \"Wed, 21 Sep 2022 16:53:52 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_auth_members.grantor is bunk\"\n }\n]","isConversational":false}}},{"rowIdx":52973,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n\nThe purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables they lack privilege to write directly. This both allows subscriptions to be managed by non-superusers, and protects servers with subscriptions from malicious activity on the publisher side.\n\n\n\n\n\n\n\n[1] https://www.postgresql.org/message-id/flat/F9408A5A-B20B-42D2-9E7F-49CD3D1547BC%40enterprisedb.com\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Wed, 20 Oct 2021 11:40:39 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Non-superuser subscription owners"},{"msg_contents":"Le mercredi 20 octobre 2021, 20:40:39 CEST Mark Dilger a écrit :\n> These patches have been split off the now deprecated monolithic \"Delegating\n> superuser tasks to new security roles\" thread at [1].\n> \n> The purpose of these patches is to allow non-superuser subscription owners\n> without risk of them overwriting tables they lack privilege to write\n> directly. This both allows subscriptions to be managed by non-superusers,\n> and protects servers with subscriptions from malicious activity on the\n> publisher side.\n\nThank you Mark for splitting this.\n\nThis patch looks good to me, and provides both better security (by closing the \n\"dropping superuser role\" loophole) and usefule features. \n\n\n-- \nRonan Dunklau\n\n\n\n\n","msg_date":"Mon, 25 Oct 2021 09:26:30 +0200","msg_from":"Ronan Dunklau <ronan.dunklau@aiven.io>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 10/20/21 14:40, Mark Dilger wrote:\n> These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n>\n> The purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables they lack privilege to write directly. This both allows subscriptions to be managed by non-superusers, and protects servers with subscriptions from malicious activity on the publisher side.\n>\n> [1] https://www.postgresql.org/message-id/flat/F9408A5A-B20B-42D2-9E7F-49CD3D1547BC%40enterprisedb.com\n\n\nThese patches look good on their face. The code changes are very\nstraightforward.\n\n\nw.r.t. this:\n\n+ On the subscriber, the subscription owner's privileges are\nre-checked for\n+ each change record when applied, but beware that a change of\nownership for a\n+ subscription may not be noticed immediately by the replication workers.\n+ Changes made on the publisher may be applied on the subscriber as\n+ the old owner. In such cases, the old owner's privileges will be\nthe ones\n+ that matter. Worse still, it may be hard to predict when replication\n+ workers will notice the new ownership. Subscriptions created\ndisabled and\n+ only enabled after ownership has been changed will not be subject to\nthis\n+ race condition.\n\n\nmaybe we should disable the subscription before making such a change and\nthen re-enable it?\n\n\ncheers\n\n\nandrew\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 1 Nov 2021 10:18:24 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"> On Nov 1, 2021, at 7:18 AM, Andrew Dunstan <andrew@dunslane.net> wrote:\n> \n> w.r.t. this:\n> \n> + On the subscriber, the subscription owner's privileges are\n> re-checked for\n> + each change record when applied, but beware that a change of\n> ownership for a\n> + subscription may not be noticed immediately by the replication workers.\n> + Changes made on the publisher may be applied on the subscriber as\n> + the old owner. In such cases, the old owner's privileges will be\n> the ones\n> + that matter. Worse still, it may be hard to predict when replication\n> + workers will notice the new ownership. Subscriptions created\n> disabled and\n> + only enabled after ownership has been changed will not be subject to\n> this\n> + race condition.\n> \n> \n> maybe we should disable the subscription before making such a change and\n> then re-enable it?\n\nRight. I commented the code that way because there is a clear concern, but I was uncertain which way around the problem was best.\n\nALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n\nThe attached patch demonstrates the race condition. It sets up a publisher and subscriber, and toggles the subscription on and off on the subscriber node, interleaved with inserts and deletes on the publisher node. If the ALTER SUBSCRIPTION commands were synchronous, the test results would be deterministic, with only the inserts performed while the subscription is enabled being replicated, but because the ALTER commands are asynchronous, the results are nondeterministic.\n\nIt is unclear that I can make ALTER SUBSCRIPTION..OWNER TO synchronous without redesigning the way workers respond to pg_subscription catalog updates generally. That may be a good project to eventually tackle, but I don't see that it is more important to close the race condition in an OWNER TO than for a DISABLE.\n\nThoughts?\n\n\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Mon, 1 Nov 2021 10:58:25 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> \n> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n\nHaving discussed this with Andrew off-list, we've concluded that updating the documentation for logical replication to make this point more clear is probably sufficient, but I wonder if anyone thinks otherwise?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 1 Nov 2021 15:44:32 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Nov 1, 2021 at 6:44 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> > ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n>\n> Having discussed this with Andrew off-list, we've concluded that updating the documentation for logical replication to make this point more clear is probably sufficient, but I wonder if anyone thinks otherwise?\n\nThe question in my mind is whether there's some reasonable amount of\ntime that a user should expect to have to wait for the changes to take\neffect. If it could easily happen that the old permissions are still\nin use a month after the change is made, I think that's probably not\ngood. If there's reason to think that, barring unusual circumstances,\nchanges will be noticed within a few minutes, I think that's fine.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 2 Nov 2021 11:17:48 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> \n> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n\nI have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\n\nThe first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\n\n\n\n\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Wed, 3 Nov 2021 12:50:28 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2021-11-01 at 10:58 -0700, Mark Dilger wrote:\n> It is unclear that I can make ALTER SUBSCRIPTION..OWNER TO\n> synchronous without redesigning the way workers respond to\n> pg_subscription catalog updates generally. That may be a good\n> project to eventually tackle, but I don't see that it is more\n> important to close the race condition in an OWNER TO than for a\n> DISABLE.\n> \n> Thoughts?\n\nWhat if we just say that OWNER TO must be done by a superuser, changing\nfrom one superuser to another, just like today? That would preserve\nbackwards compatibility, but people with non-superuser subscriptions\nwould need to drop/recreate them.\n\nWhen we eventually do tackle the problem, we can lift the restriction.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 16 Nov 2021 10:08:06 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 16, 2021, at 10:08 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> On Mon, 2021-11-01 at 10:58 -0700, Mark Dilger wrote:\n>> It is unclear .....\n>> \n>> Thoughts?\n> \n> What if we just say that OWNER TO must be done by a superuser, changing\n> from one superuser to another, just like today? That would preserve\n> backwards compatibility, but people with non-superuser subscriptions\n> would need to drop/recreate them.\n\nThe paragraph I wrote on 11/01 and you are responding to is no longer relevant. The patch submission on 11/03 tackled the problem. Have you had a chance to take a look at the new design?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 16 Nov 2021 10:12:26 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 11/3/21 15:50, Mark Dilger wrote:\n>> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n>>\n>> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\n>\n> The first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\n\n\nI'm generally happier about this than the previous patch set. With the\nexception of some slight documentation modifications I think it's\nbasically committable. There doesn't seem to be a CF item for it but I'm\ninclined to commit it in a couple of days time.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 16 Nov 2021 15:06:23 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 16, 2021, at 12:06 PM, Andrew Dunstan <andrew@dunslane.net> wrote:\n> \n> There doesn't seem to be a CF item for it but I'm\n> inclined to commit it in a couple of days time.\n\nhttps://commitfest.postgresql.org/36/3414/\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 16 Nov 2021 12:08:04 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 11/16/21 15:08, Mark Dilger wrote:\n>\n>> On Nov 16, 2021, at 12:06 PM, Andrew Dunstan <andrew@dunslane.net> wrote:\n>>\n>> There doesn't seem to be a CF item for it but I'm\n>> inclined to commit it in a couple of days time.\n> https://commitfest.postgresql.org/36/3414/\n>\n\nOK, got it, thanks.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 16 Nov 2021 15:40:54 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-03 at 12:50 -0700, Mark Dilger wrote:\n> The first two patches are virtually unchanged. The third updates the\n> behavior of the apply workers, and updates the documentation to\n> match.\n\nv2-0001 corrects some surprises, but may create others. Why is renaming\nallowed, but not changing the options? What if we add new options, and\nsome of them seem benign for a non-superuser to change?\n\nThe commit message part of the patch says that it's to prevent non-\nsuperusers from being able to (effectively) create subscriptions, but\ndon't we want privileged non-superusers to be able to create\nsubscriptions?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 16 Nov 2021 20:11:59 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 16, 2021, at 8:11 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> On Wed, 2021-11-03 at 12:50 -0700, Mark Dilger wrote:\n>> The first two patches are virtually unchanged. The third updates the\n>> behavior of the apply workers, and updates the documentation to\n>> match.\n> \n> v2-0001 corrects some surprises, but may create others. Why is renaming\n> allowed, but not changing the options? What if we add new options, and\n> some of them seem benign for a non-superuser to change?\n\nThe patch cannot anticipate which logical replication options may be added to the project in some later commit. We can let that commit adjust the behavior to allow the option if we agree it is sensible for non-superusers to do so.\n\n> The commit message part of the patch says that it's to prevent non-\n> superusers from being able to (effectively) create subscriptions, but\n> don't we want privileged non-superusers to be able to create\n> subscriptions?\n\nPerhaps, but I don't think merely owning a subscription should entitle a role to create new subscriptions. Administrators may quite intentionally create low-power users, ones without access to anything but a single table, or a single schema, as a means of restricting the damage that a subscription might do (or more precisely, what the publisher might do via the subscription.) It would be surprising if that low-power user was then able to recreate the subscription into something different.\n\nWe should probably come back to this topic in a different patch, perhaps a patch that introduces a new pg_manage_subscriptions role or such.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 07:44:27 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 07:44 -0800, Mark Dilger wrote:\n> Administrators may quite\n> intentionally create low-power users, ones without access to anything\n> but a single table, or a single schema, as a means of restricting the\n> damage that a subscription might do (or more precisely, what the\n> publisher might do via the subscription.) It would be surprising if\n> that low-power user was then able to recreate the subscription into\n> something different.\n\nI am still trying to understand this use case. It doesn't feel like\n\"ownership\" to me, it feels more like some kind of delegation.\n\nIs GRANT a better fit here? That would allow more than one user to\nREFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\nRENAME, but I don't see why we'd separate privileges for\nCREATE/DROP/RENAME anyway.\n\nThis would not address the weirdness of the existing code where a\nsuperuser loses their superuser privileges but still owns a\nsubscription. But perhaps we can solve that a different way, like just\nperforming a check when someone loses their superuser privileges that\nthey don't own any subscriptions.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 09:33:24 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> I am still trying to understand this use case. It doesn't feel like\n> \"ownership\" to me, it feels more like some kind of delegation.\n> \n> Is GRANT a better fit here? That would allow more than one user to\n> REFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\n> RENAME, but I don't see why we'd separate privileges for\n> CREATE/DROP/RENAME anyway.\n\nWe may eventually allow non-superusers to create subscriptions, but there are lots of details to work out. Should there be limits on how many subscriptions they can create? Should there be limits to the number of simultaneously open connections they can create out to other database servers (publishers)? Should they need to be granted USAGE on a database publisher in order to use the connection string for that publisher in a subscription they create? Should they need to be granted USAGE on a publication in order to replicate it? Yes, there may be restrictions on the publisher side, too, but the user model on subscriber and publisher might differ, and the connection string used might not match the subscription owner, so some restriction on the subscriber side may be needed.\n\nThe implementation of [CREATE | ALTER] SUBSCRIPTION was designed at a time when only superusers could execute them, and as far as I can infer from the design, no effort to constrain the effects of those commands was made. Since we're trying to make subscriptions into things that non-superusers can use, we have to deal with some things in those functions. For example, ALTER SUBSCRIPTION can change the database connection parameter, or the publication subscribed, or whether synchronous_commit is used. I don't see that a subscription owner should necessarily be allowed to mess with that, at least not without some other privilege checks beyond mere ownership.\n\nI think this is pretty analogous to how security definer functions work. You might call those \"delegation\" also, but the basic idea is that the function will run under the privileges of the function's owner, who might be quite privileged if you want the function to do highly secure things for you, but who could also intentionally be limited in privilege. It wouldn't make much sense to say the owner of a security definer function can arbitrarily escalate their privileges to do things like open connections to other database servers, or have the transactions in which they run have a different setting of synchronous_commit. Yet with subscriptions, if the subscription owner can run all forms of ALTER SUBSCRIPTION, that's what they can do.\n\nI took a conservative position in the design of the patch to avoid giving away too much. I suspect that we'll come back to these design decisions and relax them at some point, but the exact way in which we relax them is not obvious. We could just agree to remove them (as you seem to propose), or we might agree to create predefined roles and say that the subscription owner can change certain aspects of the subscription if and only if they are members of one or more of those roles, or we may create new grantable privileges. Each of those debates may be long and hard fought, so I don't want to invite that as part of this thread, or this patch will almost surely miss the cutoff for v15.\n\n> This would not address the weirdness of the existing code where a\n> superuser loses their superuser privileges but still owns a\n> subscription. But perhaps we can solve that a different way, like just\n> performing a check when someone loses their superuser privileges that\n> they don't own any subscriptions.\n\nI gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 10:25:50 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> Is GRANT a better fit here? That would allow more than one user to\n> REFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\n> RENAME, but I don't see why we'd separate privileges for\n> CREATE/DROP/RENAME anyway.\n\nI don't think I answered this directly in my last reply.\n\nGRANT *might* be part of some solution, but it is unclear to me how best to do it. The various configuration parameters on subscriptions entail different security concerns. We might take a fine-grained approach and create a predefined role for each, or we might take a course-grained approach and create a single pg_manage_subscriptions role which can set any parameter on any subscription, or maybe just parameters on subscriptions that the role also owns, or we might do something else, like burn some privilege bits and define new privileges that can be granted per subscription rather than globally. (I think that last one is a non-starter, but just mention it as an example of another approach.)\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 10:48:44 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 11/16/21 15:06, Andrew Dunstan wrote:\n> On 11/3/21 15:50, Mark Dilger wrote:\n>>> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n>>>\n>>> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n>> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\n>>\n>> The first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\n>\n> I'm generally happier about this than the previous patch set. With the\n> exception of some slight documentation modifications I think it's\n> basically committable. There doesn't seem to be a CF item for it but I'm\n> inclined to commit it in a couple of days time.\n>\n>\n\nGiven there is some debate about the patch set I will hold off any\naction for the time being.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Wed, 17 Nov 2021 15:26:41 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 10:25 -0800, Mark Dilger wrote:\n> We may eventually allow non-superusers to create subscriptions, but\n> there are lots of details to work out.\n\nI am setting aside the idea of subscriptions created by non-superusers.\n\nMy comments were about your idea for \"low-power users\" that can still\ndo things with subscriptions. And for that, GRANT seems like a better\nfit than ownership.\n\nWith v2-0001, there are several things that seem weird to me:\n\n * Why can there be only one low-power user per subscription?\n * Why is RENAME a separate capability from CREATE/DROP?\n * What if you want to make the privileges more fine-grained, or make\nchanges in the future? Ownership is a single bit, so it requires that\neveryone agree. Maybe some people want RENAME to be a part of that, and\nothers don't.\n\nGRANT seems to provide better answers here.\n\n> Since we're trying to make subscriptions into things that non-\n> superusers can use, we have to deal with some things in those\n> functions.\n\nI understand the use case where a superuser isn't required anywhere in\nthe process, and some special users can create and own subscriptions. I\nalso understand that's not what these patches are trying to accomplish\n(though v2-0003 seems like a good step in that direction).\n\nI don't understand the use case as well where a non-superuser can\nmerely \"use\" a subscription. I'm sure such use cases exist and I'm fine\nto go along with that idea, but I'd like to understand why ownership\n(partial ownership?) is the right way to do this and GRANT is the wrong\nway.\n\n> For example, ALTER SUBSCRIPTION can change the database connection\n> parameter, or the publication subscribed, or whether\n> synchronous_commit is used. I don't see that a subscription owner\n> should necessarily be allowed to mess with that, at least not without\n> some other privilege checks beyond mere ownership.\n\nThat violates my expectations of what \"ownership\" means.\n\n> I think this is pretty analogous to how security definer functions\n> work.\n\nThe analogy to SECURITY DEFINER functions seems to support my\nsuggestion for GRANT at least as much as your modified definition of\nownership.\n\n> > This would not address the weirdness of the existing code where a\n> > superuser loses their superuser privileges but still owns a\n> > subscription. But perhaps we can solve that a different way, like\n> > just\n> > performing a check when someone loses their superuser privileges\n> > that\n> > they don't own any subscriptions.\n> \n> I gave that a slight amount of thought during the design of this\n> patch, but didn't think we could refuse to revoke superuser on such a\n> basis,\n\nI don't necessarily see a problem there, but I could be missing\nsomething.\n\n> and didn't see what we should do with the subscription other than\n> have it continue to be owned by the recently-non-superuser. If you\n> have a better idea, we can discuss it, but to some degree I think\n> that is also orthogonal to the purpose of this patch. The only sense\n> in which this patch depends on that issue is that this patch proposes\n> that non-superuser subscription owners are already an issue, and\n> therefore that this patch isn't creating a new issue, but rather\n> making more sane something that already can happen.\n\nBy introducing and documenting a way to get non-superusers to own a\nsubscription, it makes it more likely that people will do it, and\nharder for us to change. That means the standard should be \"this is\nwhat we really want\", rather than just \"more sane than before\".\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 13:06:32 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 10:48 -0800, Mark Dilger wrote:\n> GRANT *might* be part of some solution, but it is unclear to me how\n> best to do it. The various configuration parameters on subscriptions\n> entail different security concerns. We might take a fine-grained\n> approach and create a predefined role for each\n\nI think you misunderstood the idea: not using predefined roles, just\nplain old ordinary GRANT on a subscription object to ordinary roles.\n\n GRANT REFRESH ON SUBSCRIPTION sub1 TO nonsuper;\n\nThis should be easy enough because the subscription is a real object,\nright?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 13:10:20 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 17, 2021, at 1:10 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> I think you misunderstood the idea: not using predefined roles, just\n> plain old ordinary GRANT on a subscription object to ordinary roles.\n> \n> GRANT REFRESH ON SUBSCRIPTION sub1 TO nonsuper;\n> \n> This should be easy enough because the subscription is a real object,\n> right?\n\n/*\n * Grantable rights are encoded so that we can OR them together in a bitmask.\n * The present representation of AclItem limits us to 16 distinct rights,\n * even though AclMode is defined as uint32. See utils/acl.h.\n *\n * Caution: changing these codes breaks stored ACLs, hence forces initdb.\n */\ntypedef uint32 AclMode; /* a bitmask of privilege bits */\n\n#define ACL_INSERT (1<<0) /* for relations */\n#define ACL_SELECT (1<<1)\n#define ACL_UPDATE (1<<2)\n#define ACL_DELETE (1<<3)\n#define ACL_TRUNCATE (1<<4)\n#define ACL_REFERENCES (1<<5)\n#define ACL_TRIGGER (1<<6)\n#define ACL_EXECUTE (1<<7) /* for functions */\n#define ACL_USAGE (1<<8) /* for languages, namespaces, FDWs, and\n * servers */\n#define ACL_CREATE (1<<9) /* for namespaces and databases */\n#define ACL_CREATE_TEMP (1<<10) /* for databases */\n#define ACL_CONNECT (1<<11) /* for databases */\n\n\nWe only have 4 values left in the bitmask, and I doubt that burning those slots for multiple new types of rights that only have meaning for subscriptions is going to be accepted. For full disclosure, I'm proposing adding ACL_SET and ACL_ALTER_SYSTEM in another patch and my proposal there could get shot down for the same reasons, but I think your argument would be even harder to defend. Maybe others feel differently.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 15:07:10 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 15:07 -0800, Mark Dilger wrote:\n> We only have 4 values left in the bitmask, and I doubt that burning\n> those slots for multiple new types of rights that only have meaning\n> for subscriptions is going to be accepted. For full disclosure, I'm\n> proposing adding ACL_SET and ACL_ALTER_SYSTEM in another patch and my\n> proposal there could get shot down for the same reasons, but I think\n> your argument would be even harder to defend. Maybe others feel\n> differently.\n\nWhy not overload ACL_USAGE again, and say:\n\n GRANT USAGE ON SUBSCRIPTION sub1 TO nonsuper;\n\nwould allow ENABLE/DISABLE and REFRESH.\n\nAgain, I don't really understand the use case behind \"can use a\nsubscription but not create one\", so I'm not making a proposal. But\nassuming that the use case exists, GRANT seems like a much better\napproach.\n\n(Aside: for me to commit something like this I'd want to understand the\n\"can use a subscription but not create one\" use case better.)\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 15:46:55 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 17, 2021, at 1:06 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> On Wed, 2021-11-17 at 10:25 -0800, Mark Dilger wrote:\n>> We may eventually allow non-superusers to create subscriptions, but\n>> there are lots of details to work out.\n> \n> I am setting aside the idea of subscriptions created by non-superusers.\n\nOk, fair enough. I think eventually we'll want that, but I'm also setting that aside for this patch.\n\n> My comments were about your idea for \"low-power users\" that can still\n> do things with subscriptions. And for that, GRANT seems like a better\n> fit than ownership.\n\nThis patch has basically no value beyond the fact that it allows the replication to be *applied* as a user other than superuser. Throw that out, and there isn't any point. Everything else is window dressing. The real security problem with subscriptions is that they act with superuser power. That naturally means that they must be owned and operated by superuser, too, otherwise they serve as a privilege escalation attack vector. It really doesn't make any sense to think of subscriptions as operating under the permissions of multiple non-superusers. You must choose a single role you want the subscription to run under. What purpose would be served by GRANTing privileges on a subscription to more than one non-superuser? It still operates as just the one user. I agree you *could* give multiple users privileges to mess with it, but you'd still need to assign a single role as the one whose privileges matter for the purpose of applying replication changes. I'm using \"owner\" for that purpose, and I think that is consistent with how security definer functions work. They run as the owner, too. It's perfectly well-precedented to use \"owner\" for this.\n\nI think the longer term plan is that non-superusers who have some privileged role will be allowed to create subscriptions, and naturally they will own the subscriptions that they create, at least until an ALTER SUBSCRIPTION..OWNER TO is successfully executed to transfer ownership. Once that longer term plan is complete, non-superusers will be able to create publications of their tables on one database, and subscriptions to those publications on another database, all without needing the help of a superuser. This patch doesn't get us all the way there, but it heads directly toward that goal.\n\n> With v2-0001, there are several things that seem weird to me:\n> \n> * Why can there be only one low-power user per subscription?\n\nBecause the apply workers run as only one user. Currently it is always superuser. After this patch, it is always the owner, which amounts to the same thing for legacy subscriptions created and owned by superuser prior to upgrading to v15, but not necessarily for new ones or ones that have ownership transferred after upgrade.\n\nWe could think about subscriptions that act under multiple roles, perhaps taking role information as part of the data-stream from the publisher, but that's a pretty complicated proposal, and it is far from clear that we want it anyway. There is a security case to be made for *not* allowing the publisher to call all the shots, so such a proposal would at best be an alternate mode of operation, not the one and only mode.\n\n> * Why is RENAME a separate capability from CREATE/DROP?\n\nI don't care enough to argue this point. If you want me to remove RENAME privilege from the owner, I can resubmit with it removed. It just doesn't seem like it's dangerous to allow a non-superuser to rename their subscriptions, so I saw no compelling reason to disallow it.\n\nCREATE clearly must be disallowed since it gives the creator the ability to form network connections, set fsync modes, etc., and there is no reason to assume arbitrary non-superusers should be able to do that.\n\nThe argument against DROP is a bit weaker. It doesn't seem like a user who cannot bring subscriptions into existence should be able to drop them either. I was expecting to visit that issue in a follow-on patch which deals with non-superuser predefined roles that have some power to create and drop subscriptions. What that patch will propose to do is not obvious, since some of what you can do with subscriptions is so powerful we may not want non-superusers doing it, even with a privileged role. If you can't picture what I mean, consider that you might use a connection parameter that connects outside and embeds data into the connection string, with a server listening on the other end, not really to publish data, but to harvest the secret data that you are embedding in the network connection attempt.\n\n> * What if you want to make the privileges more fine-grained, or make\n> changes in the future? Ownership is a single bit, so it requires that\n> everyone agree.\n\nWe can modify the patch to have the subscription owner have zero privileges on the subscription, not even the ability to see how it is defined, and just have \"owner\" mean the role under whose privileges the logical replication workers apply changes. Would that be better? I would expect people to find that odd.\n\nThe problem is that we want a setuid/setgid type behavior. Actual setuid/setgid programs act as the user/group of the executable. There's no reason that user/group needs to be one that any real human uses to log into the system. Likewise, we need the subscription to act under a role, and we're establishing which role that is by having that role own the subscription. That is like how setuid/setgid programs work by executing as the user/group that owns the executable, except that postgres doesn't have separate user/group concepts, just roles. Isn't this design pattern completely commonplace?\n\n> Maybe some people want RENAME to be a part of that, and\n> others don't.\n\nFair enough. Should I remove RENAME from what the patch allows the owner to do? On this particular point, I genuinely don't care. I think it can be reasonably argued either way.\n\n> GRANT seems to provide better answers here.\n\nNo, because we don't have infinite privilege bits to burn.\n\n>> Since we're trying to make subscriptions into things that non-\n>> superusers can use, we have to deal with some things in those\n>> functions.\n> \n> I understand the use case where a superuser isn't required anywhere in\n> the process, and some special users can create and own subscriptions. I\n> also understand that's not what these patches are trying to accomplish\n> (though v2-0003 seems like a good step in that direction).\n\nThere is a cart-before-the-horse problem here. If I propose a patch with a privileged role for creating and owning subscriptions *before* I tighten down how non-superuser-owned subscriptions work, that patch would surely be rejected. So I either propose this first, and only if/when it gets accepted, propose the other, or I propose them together. That's a damned-if-you-do--damned-if-you-dont situation, because if I propose them together, I'll get arguments that they are clearly separable and should be proposed separately, and if I do them one before the other, I'll get the argument that you are making now. I fully expect the privileged role proposal to be made (possibly by me), though it is unclear if there will be time left to do it in v15.\n\n> I don't understand the use case as well where a non-superuser can\n> merely \"use\" a subscription. I'm sure such use cases exist and I'm fine\n> to go along with that idea, but I'd like to understand why ownership\n> (partial ownership?) is the right way to do this and GRANT is the wrong\n> way.\n\nEven if we had the privilege bits to burn, no spelling of that GRANT idea sounds all that great:\n\n\tGRANT RUN AS ON subscription TO role;\n\tGRANT RUN AS ON role TO subscription;\n\tGRANT SUDO ON subscription TO role;\n\tGRANT SETUID ON role TO subscription;\n\t...\n\nI just don't see how that really works. I'm not inclined to spend time being more clever, since I already know that privilege bits are in short supply, but if you want to propose something, go ahead. Elsewhere you proposed GRANT REFRESH or something, not looking at that email just now, but that's not the same thing as GRANT RUN AS, and burns another privilege bit, and still doesn't get us all the way there, because you presumably also want GRANT RENAME, GRANT ALTER CONNECTION SETTING, GRANT ALTER FSYNC SETTING, ..., and we're out of privilege bits before we're done.\n\n>> For example, ALTER SUBSCRIPTION can change the database connection\n>> parameter, or the publication subscribed, or whether\n>> synchronous_commit is used. I don't see that a subscription owner\n>> should necessarily be allowed to mess with that, at least not without\n>> some other privilege checks beyond mere ownership.\n> \n> That violates my expectations of what \"ownership\" means.\n\nI think that's because you're thinking of these settings as properties of the subscription. You may *own* the subscription, but the subscription doesn't *own* the right to make connections to arbitrary databases, nor *own* the right to change buffer cache settings, nor *own* the right to bring data from a publication on some other server which, if it existed on the local server, would violate site policy and possibly constitute a civil or criminal violation of data privacy laws. I may own my house, and the land it sits on, and my driveway, but that doesn't mean I own the ability to make my driveway go across my neighbor's field, down through town, and to the waterfront. But that's the kind of ownership definition you seem to be defending.\n\nSome of what I perceive as the screwiness of your argument I must admin is not your fault. The properties of subscriptions are defined in ways that don't make sense to me. It would be far more sensible if connection strings were objects in their own right, and you could grant USAGE on a connection string to a role, and USAGE on a subscription to a role, and only if the subscription worker's role had privileges on the connection string could they use it as part of fulfilling their task of replicating the data, and otherwise they'd error out in the attempt. Likewise, fsync modes could be proper objects, and only if the subscription's role had privileges on the fsync mode they wanted to use would they be able to use it. But we don't have these things as proper objects, with acl lists on them, so we're stuck trying to design around that. To my mind, that means subscription owners *do not own* properties associated with the subscription. To your mind, that's not what \"ownership\" means. What to do?\n\n>> I think this is pretty analogous to how security definer functions\n>> work.\n> \n> The analogy to SECURITY DEFINER functions seems to support my\n> suggestion for GRANT at least as much as your modified definition of\n> ownership.\n\nI don't see how. Can you please explain?\n\n>>> This would not address the weirdness of the existing code where a\n>>> superuser loses their superuser privileges but still owns a\n>>> subscription. But perhaps we can solve that a different way, like\n>>> just\n>>> performing a check when someone loses their superuser privileges\n>>> that\n>>> they don't own any subscriptions.\n>> \n>> I gave that a slight amount of thought during the design of this\n>> patch, but didn't think we could refuse to revoke superuser on such a\n>> basis,\n> \n> I don't necessarily see a problem there, but I could be missing\n> something.\n\nClose your eyes and imagine that I have superuser on your database... really picture it in your mind. Now, do you want the revoke command you are issuing to work?\n\n>> and didn't see what we should do with the subscription other than\n>> have it continue to be owned by the recently-non-superuser. If you\n>> have a better idea, we can discuss it, but to some degree I think\n>> that is also orthogonal to the purpose of this patch. The only sense\n>> in which this patch depends on that issue is that this patch proposes\n>> that non-superuser subscription owners are already an issue, and\n>> therefore that this patch isn't creating a new issue, but rather\n>> making more sane something that already can happen.\n> \n> By introducing and documenting a way to get non-superusers to own a\n> subscription, it makes it more likely that people will do it, and\n> harder for us to change. That means the standard should be \"this is\n> what we really want\", rather than just \"more sane than before\".\n\nOk, I'll wait to hear back from you on the points above.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 17 Nov 2021 16:17:42 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Nov 17, 2021 at 11:56 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> > On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> >\n>\n> > This would not address the weirdness of the existing code where a\n> > superuser loses their superuser privileges but still owns a\n> > subscription. But perhaps we can solve that a different way, like just\n> > performing a check when someone loses their superuser privileges that\n> > they don't own any subscriptions.\n>\n> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\n>\n\nDon't we want to close this gap irrespective of the other part of the\nfeature? I mean if we take out the part of your 0003 patch that checks\nwhether the current user has permission to perform a particular\noperation on the target table then the gap related to the owner losing\nsuperuser privileges should be addressed.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 18 Nov 2021 16:20:01 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Nov 4, 2021 at 1:20 AM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n>\n> > On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> >\n> > ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\n>\n> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record.\n>\n\nAre you talking about the below change in the above paragraph?\n\n@@ -2912,6 +2941,7 @@ maybe_reread_subscription(void)\n strcmp(newsub->slotname, MySubscription->slotname) != 0 ||\n newsub->binary != MySubscription->binary ||\n newsub->stream != MySubscription->stream ||\n+ newsub->owner != MySubscription->owner ||\n !equal(newsub->publications, MySubscription->publications))\n {\n\nIf so, I am not sure how it will ensure that we check the ownership\nchange before applying each change? I think this will be invoked at\neach transaction boundary, so, if there is a transaction with a large\nnumber of changes, all the changes will be processed under the\nprevious owner.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 18 Nov 2021 17:07:47 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 18, 2021, at 2:50 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n>> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\n>> \n> \n> Don't we want to close this gap irrespective of the other part of the\n> feature? I mean if we take out the part of your 0003 patch that checks\n> whether the current user has permission to perform a particular\n> operation on the target table then the gap related to the owner losing\n> superuser privileges should be addressed.\n\nI don't think there is a gap. The patch does the right thing, causing the subscription whose owner has had superuser revoked to itself no longer function with superuser privileges. Whether that causes the subscription to fail depends on whether the previously-superuser now non-superuser owner now lacks sufficient privileges on the target relation(s). I think removing that part of the patch would be a regression.\n\nLet's compare two scenarios. In the first, we have a regular user \"alice\" who owns a subscription which replicates into table \"accounting.receipts\" for which she has been granted privileges by the table's owner. What would you expect to happen after the table's owner revokes privileges from alice? I would expect that the subscription can no longer function, and periodic attempts to replicate into that table result in permission denied errors in the logs.\n\nIn the second, we have a superuser \"alice\" who owns a subscription that replicates into table \"accounting.receipts\", and she only has sufficient privileges to modify \"accounting.receipts\" by virtue of being superuser. I would expect that when she has superuser revoked, the subscription can likewise no longer function. \n\nNow, maybe I'm wrong in both cases, and both should continue to function. But I would find it really strange if the first situation behaved differently from the second.\n\nI think intuitions about how subscriptions behave differ depending on the reason you expect the subscription to be owned by a particular user. If the reason the user owns the subscription is that the user just happens to be the user who created it, but isn't in your mind associated with the subscription, then having the subscription continue to function regardless of what happens to the user, even the user being dropped, is probably consistent with your expectations. In a sense, you think of the user who creates the subscription as having gifted it to the universe rather than continuing to own it. Or perhaps you think of the creator of the subscription as a solicitor/lawyer/agent working on behalf of client, and once that legal transaction is completed, you don't expect the lawyer being disbarred should impact the subscription which exists for the benefit of the client.\n\nIf instead you think about the subscription owner as continuing to be closely associated with the subscription (as I do), then you expect changes in the owner's permissions to impact the subscription.\n\nI think the \"gifted to the universe\"/\"lawyer\" mental model is not consistent with how the system is already designed to work. You can't drop the subscription's owner without first running REASSIGN OWNED, or ALTER SUBSCRIPTION..OWNER TO, or simply dropping the subscription:\n\n DROP ROLE regress_subscription_user;\n ERROR: role \"regress_subscription_user\" cannot be dropped because some objects depend on it\n DETAIL: owner of subscription regress_testsub\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Thu, 18 Nov 2021 07:33:53 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 18, 2021, at 3:37 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n>> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record.\n>> \n> \n> Are you talking about the below change in the above paragraph?\n> \n> @@ -2912,6 +2941,7 @@ maybe_reread_subscription(void)\n> strcmp(newsub->slotname, MySubscription->slotname) != 0 ||\n> newsub->binary != MySubscription->binary ||\n> newsub->stream != MySubscription->stream ||\n> + newsub->owner != MySubscription->owner ||\n> !equal(newsub->publications, MySubscription->publications))\n> {\n> \n> If so, I am not sure how it will ensure that we check the ownership\n> change before applying each change? I think this will be invoked at\n> each transaction boundary, so, if there is a transaction with a large\n> number of changes, all the changes will be processed under the\n> previous owner.\n\nYes, your analysis appears correct. I was sloppy to say \"before applying the next record\". It will pick up the change before applying the next transaction.\n\nThe prior version of the patch only picked up the change if it happened to start a new worker, but could process multiple transactions without noticing the change. Now, it is limited to finishing the current transaction. Would you prefer that the worker noticed the change in ownership and aborted the transaction on the subscriber side? Or should the ALTER SUBSCRIPTION..OWNER TO block? I don't see much advantage to either of those options, but I also don't think I have any knock-down argument for my approach either. What do you think?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Thu, 18 Nov 2021 07:45:13 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\n> You must choose a single role you want the subscription to run\n> under.\n\nI think that was the source of a lot of my confusion: \n\nYour patches are creating the notion of a \"run as\" user by assigning\nownership-that-isn't-really-ownership. I got distracted wondering why\nyou would really care if some user could enable/disable/refresh/rename\na subscription, but the main point was to change who the subscription\nruns as.\n\nThat's a more general idea: I could see how \"run as\" could apply to\nsubscriptions as well as functions (right now it can only run as the\nowner or the invoker, not an arbitrary role). And I better understand\nyour analogy to security definer now.\n\nBut it's also not exactly a simple idea, and I think the current\npatches oversimplify it and conflate it with ownership. \n\n> I think the longer term plan is that non-superusers who have some\n> privileged role will be allowed to create subscriptions,\n\nYou earlier listed some challenges with that:\n\n\nhttps://postgr.es/m/CF56AC0D-7495-4E8D-A48F-FF38BD8074EB@enterprisedb.com\n\nBut it seems like it's really the right direction to go. Probably the\nbiggest concern is connection strings that read server files, but\ndblink solved that by requiring password auth.\n\nWhat are the reasonable steps to get there? Do you think anything is\ndoable for v15?\n\n> There is a cart-before-the-horse problem here.\n\nI don't think we need to hold up v2-0003. It seems like a step in the\nright direction, though I haven't looked closely yet.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Thu, 18 Nov 2021 10:29:26 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\n> Some of what I perceive as the screwiness of your argument I must\n> admin is not your fault. The properties of subscriptions are defined\n> in ways that don't make sense to me. It would be far more sensible\n> if connection strings were objects in their own right, and you could\n> grant USAGE on a connection string to a role,\n\nWe sort of have that with CREATE SERVER, in fact dblink can use a\nserver instead of a string. \n\nRegards,\n\tJeff Davis\n\n\n\n\n\n","msg_date":"Thu, 18 Nov 2021 10:50:29 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Nov 18, 2021 at 9:03 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> > On Nov 18, 2021, at 2:50 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >\n> >> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\n> >>\n> >\n> > Don't we want to close this gap irrespective of the other part of the\n> > feature? I mean if we take out the part of your 0003 patch that checks\n> > whether the current user has permission to perform a particular\n> > operation on the target table then the gap related to the owner losing\n> > superuser privileges should be addressed.\n>\n> I don't think there is a gap. The patch does the right thing, causing the subscription whose owner has had superuser revoked to itself no longer function with superuser privileges. Whether that causes the subscription to fail depends on whether the previously-superuser now non-superuser owner now lacks sufficient privileges on the target relation(s). I think removing that part of the patch would be a regression.\n>\n\nI think we are saying the same thing. I intend to say that your 0003*\npatch closes the current gap in the code and we should consider\napplying it irrespective of what we do with respect to changing the\n... OWNER TO .. behavior. Is there a reason why 0003* patch (or\nsomething on those lines) shouldn't be considered to be applied?\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 19 Nov 2021 15:14:40 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Nov 18, 2021 at 9:15 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> The prior version of the patch only picked up the change if it happened to start a new worker, but could process multiple transactions without noticing the change. Now, it is limited to finishing the current transaction. Would you prefer that the worker noticed the change in ownership and aborted the transaction on the subscriber side? Or should the ALTER SUBSCRIPTION..OWNER TO block? I don't see much advantage to either of those options, but I also don't think I have any knock-down argument for my approach either. What do you think?\n>\n\nHow about allowing to change ownership only for disabled\nsubscriptions? Basically, users need to first disable the subscription\nand then change its ownership. Now, disabling is an asynchronous\noperation but we won't allow the ownership change command to proceed\nunless the subscription is marked disabled and all the apply/sync\nworkers are not running. After the ownership is changed, users can\nenable it. We already have 'slot_name' parameter's dependency on\nwhether the subscription is marked enabled or not.\n\nThis will add some steps in changing the ownership of a subscription\nbut I think it will be predictable.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 19 Nov 2021 15:26:09 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Nov 19, 2021 at 12:00 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\n> > You must choose a single role you want the subscription to run\n> > under.\n>\n> I think that was the source of a lot of my confusion:\n>\n> Your patches are creating the notion of a \"run as\" user by assigning\n> ownership-that-isn't-really-ownership. I got distracted wondering why\n> you would really care if some user could enable/disable/refresh/rename\n> a subscription, but the main point was to change who the subscription\n> runs as.\n>\n> That's a more general idea: I could see how \"run as\" could apply to\n> subscriptions as well as functions (right now it can only run as the\n> owner or the invoker, not an arbitrary role). And I better understand\n> your analogy to security definer now.\n>\n\nI was thinking why not separate the ownership and \"run as\" privileges\nfor the subscriptions? We can introduce a new syntax in addition to\nthe current syntax for \"Owner\" for this as:\n\nCreate Subscription sub RUNAS <role_name> ...;\nAlter Subscription sub RUNAS <role_name>\n\nNow, RUNAS role will be used to apply changes and perform the initial\ntable sync. The owner will be tied to changing some of the other\nproperties (enabling, disabling, etc.) of the subscription. Now, we\nstill need a superuser to create subscription and change properties\nlike CONNECTION for a subscription but we can solve that by having\nroles specific to it as being indicated by Mark in some of his\nprevious emails.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 19 Nov 2021 15:53:08 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 19, 2021, at 1:44 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> I think we are saying the same thing. I intend to say that your 0003*\n> patch closes the current gap in the code and we should consider\n> applying it irrespective of what we do with respect to changing the\n> ... OWNER TO .. behavior. Is there a reason why 0003* patch (or\n> something on those lines) shouldn't be considered to be applied?\n\nJeff Davis and I had a long conversation off-list yesterday and reached the same conclusion. I will be submitting a version of 0003 which does not depend on the prior two patches.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Fri, 19 Nov 2021 07:25:49 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 19, 2021, at 1:56 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> How about allowing to change ownership only for disabled\n> subscriptions? Basically, users need to first disable the subscription\n> and then change its ownership.\n\nThere are some open issues about non-superuser owners that Jeff would like to address before allowing transfers of ownership to non-superusers. Your proposal about requiring the subscription to be disabled seems reasonable to me, but I'd like to see how it would interact with whatever Jeff proposes. So I think I will change the patch as you suggest, but consider it a WIP patch until then.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Fri, 19 Nov 2021 07:47:06 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 19, 2021, at 2:23 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> I was thinking why not separate the ownership and \"run as\" privileges\n> for the subscriptions? We can introduce a new syntax in addition to\n> the current syntax for \"Owner\" for this as:\n> \n> Create Subscription sub RUNAS <role_name> ...;\n> Alter Subscription sub RUNAS <role_name>\n> \n> Now, RUNAS role will be used to apply changes and perform the initial\n> table sync. The owner will be tied to changing some of the other\n> properties (enabling, disabling, etc.) of the subscription. Now, we\n> still need a superuser to create subscription and change properties\n> like CONNECTION for a subscription but we can solve that by having\n> roles specific to it as being indicated by Mark in some of his\n> previous emails.\n\nI feel disquieted about the \"runas\" idea. I can't really say why yet. Maybe it is ok, but it feels like a larger design decision than just an implementation detail about how subscriptions work. We should consider if we won't soon be doing the same thing for other parts of the system. If so, we should choose a solution that makes sense when applied more broadly.\n\nSecurity definer functions could benefit from splitting the owner from the runas role.\n\nEvent triggers might benefit from having a runas role. Currently, event triggers are always owned by superusers, but we've discussed allowing non-superuser owners. That proposal still has outstanding issues to be resolved, so I can't be sure if runas would be helpful, but it might.\n\nTable triggers might benefit from having a runas role. I don't have a proposal here, just an intuition that we should think about this before designing how \"runas\" works.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Fri, 19 Nov 2021 08:12:27 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"> On Nov 19, 2021, at 7:25 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> \n> Jeff Davis and I had a long conversation off-list yesterday and reached the same conclusion. I will be submitting a version of 0003 which does not depend on the prior two patches.\n\nRenamed as 0001 in version 3, as it is the only remaining patch. For anyone who reviewed the older patch set, please note that I made some changes to the src/test/subscription/t/026_nosuperuser.pl test case relative to the prior version.\n\n\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Fri, 19 Nov 2021 16:45:50 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, 2021-11-19 at 16:45 -0800, Mark Dilger wrote:\n> Renamed as 0001 in version 3, as it is the only remaining patch. For\n> anyone who reviewed the older patch set, please note that I made some\n> changes to the src/test/subscription/t/026_nosuperuser.pl test case\n> relative to the prior version.\n\nWe need to do permission checking for WITH CHECK OPTION and RLS. The\npatch right now allows the subscription to write data that an RLS\npolicy forbids.\n\nA couple other points:\n\n * We shouldn't refer to the behavior of previous versions in the docs\nunless there's a compelling reason\n * Do we need to be smarter about partitioned tables, where an insert\ncan turn into an update?\n * Should we refactor to borrow logic from ExecInsert so that it's less\nlikely that we miss something in the future?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Wed, 24 Nov 2021 16:30:06 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Nov 25, 2021 at 6:00 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Fri, 2021-11-19 at 16:45 -0800, Mark Dilger wrote:\n> > Renamed as 0001 in version 3, as it is the only remaining patch. For\n> > anyone who reviewed the older patch set, please note that I made some\n> > changes to the src/test/subscription/t/026_nosuperuser.pl test case\n> > relative to the prior version.\n>\n> We need to do permission checking for WITH CHECK OPTION and RLS. The\n> patch right now allows the subscription to write data that an RLS\n> policy forbids.\n>\n\nWon't it be better to just check if the current user is superuser\nbefore applying each change as a matter of this first patch? Sorry, I\nwas under impression that first, we want to close the current gap\nwhere we allow to proceed with replication if the user's superuser\nprivileges were revoked during replication. To allow non-superusers\nowners, I thought it might be better to first try to detect the change\nof ownership as soon as possible instead of at the transaction\nboundary.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 25 Nov 2021 09:51:22 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2021-11-25 at 09:51 +0530, Amit Kapila wrote:\n> Won't it be better to just check if the current user is superuser\n> before applying each change as a matter of this first patch? Sorry, I\n> was under impression that first, we want to close the current gap\n> where we allow to proceed with replication if the user's superuser\n> privileges were revoked during replication.\n\nThat could be a first step, and I don't oppose it. But it seems like a\nvery small first step that would be made obsolete when v3-0001 is\nready, which I think will be very soon.\n\n> To allow non-superusers\n> owners, I thought it might be better to first try to detect the\n> change\n> of ownership\n\nIn the case of revoked superuser privileges, there's no change in\nownership, just a change of privileges (SUPERUSER -> NOSUPERUSER). And\nif we're detecting a change of privileges, why not just do it in\nsomething closer to the right way, which is what v3-0001 is attempting\nto do.\n\n> as soon as possible instead of at the transaction\n> boundary.\n\nI don't understand why it's important to detect a loss of privileges\nfaster than a transaction boundary. Can you elaborate?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Thu, 25 Nov 2021 12:06:36 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> We need to do permission checking for WITH CHECK OPTION and RLS. The\n> patch right now allows the subscription to write data that an RLS\n> policy forbids.\n\nThanks for reviewing and for this observation! I can verify that RLS is not being honored on the subscriber side. I agree this is a problem for subscriptions owned by non-superusers.\n\nThe implementation of the table sync worker uses COPY FROM, which makes this problem hard to fix, because COPY FROM does not support row level security. We could do some work to honor the RLS policies during the apply workers' INSERT statements, but then some data would circumvent RLS during table sync and other data would honor RLS during worker apply, which would make the implementation not only wrong but inconsistently so.\n\nI think a more sensible approach for v15 is to raise an ERROR if a non-superuser owned subscription is trying to replicate into a table which has RLS enabled. We might try to be more clever and check whether the RLS policies could possibly reject the operation (by comparing the TO and FOR clauses of the policies against the role and operation type) but that seems like a partial re-implementation of RLS. It would be simpler and more likely correct if we just unconditionally reject replicating into tables which have RLS enabled.\n\nWhat do you think?\n\n> A couple other points:\n> \n> * We shouldn't refer to the behavior of previous versions in the docs\n> unless there's a compelling reason\n\nFair enough.\n\n> * Do we need to be smarter about partitioned tables, where an insert\n> can turn into an update?\n\nDo you mean an INSERT statement with an ON CONFLICT DO UPDATE clause that is running against a partitioned table? If so, I don't think we need to handle that on the subscriber side under the current logical replication design. I would expect the plain INSERT or UPDATE that ultimately executes on the publisher to be what gets replicated to the subscriber, and not the original INSERT .. ON CONFLICT DO UPDATE statement.\n\n> * Should we refactor to borrow logic from ExecInsert so that it's less\n> likely that we miss something in the future?\n\nHooking into the executor at a higher level, possibly ExecInsert or ExecModifyTable would do a lot more than what logical replication currently does. If we also always used INSERT/UPDATE/DELETE statements and never COPY FROM statements, we might solve several problems at once, including honoring RLS policies and honoring rules defined for the target table on the subscriber side.\n\nDoing this would clearly be a major design change, and possibly one we do not want. Can we consider this out of scope?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Sat, 27 Nov 2021 10:05:16 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Nov 26, 2021 at 1:36 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> > as soon as possible instead of at the transaction\n> > boundary.\n>\n> I don't understand why it's important to detect a loss of privileges\n> faster than a transaction boundary. Can you elaborate?\n>\n\nThe first reason is that way it would be consistent with what we can\nsee while doing the operations from the backend. For example, if we\nrevoke privileges from the user during the transaction, the results\nwill be reflected.\npostgres=> Begin;\nBEGIN\npostgres=*> insert into t1 values(1);\nINSERT 0 1\npostgres=*> insert into t1 values(2);\nERROR: permission denied for table t1\n\nIn this case, after the first insert, I have revoked the privileges of\nthe user from table t1 and the same is reflected in the very next\noperation. Another reason is to make behavior predictable as users can\nalways expect when exactly the privilege change will be reflected and\nit won't depend on the number of changes in the transaction.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Mon, 29 Nov 2021 09:43:41 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Nov 27, 2021 at 11:37 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n>\n>\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> >\n> > We need to do permission checking for WITH CHECK OPTION and RLS. The\n> > patch right now allows the subscription to write data that an RLS\n> > policy forbids.\n>\n> Thanks for reviewing and for this observation! I can verify that RLS is not being honored on the subscriber side. I agree this is a problem for subscriptions owned by non-superusers.\n>\n...\n>\n> > A couple other points:\n> >\n>\n> > * Do we need to be smarter about partitioned tables, where an insert\n> > can turn into an update?\n>\n> Do you mean an INSERT statement with an ON CONFLICT DO UPDATE clause that is running against a partitioned table? If so, I don't think we need to handle that on the subscriber side under the current logical replication design. I would expect the plain INSERT or UPDATE that ultimately executes on the publisher to be what gets replicated to the subscriber, and not the original INSERT .. ON CONFLICT DO UPDATE statement.\n>\n\nYeah, that is correct but I think the update case is more relevant\nhere. In ExecUpdate(), we convert Update to DELETE+INSERT when the\npartition constraint is failed whereas, on the subscriber-side, it\nwill simply fail in this case. It is not clear to me how that is\ndirectly related to this patch but surely it will be a good\nimprovement on its own and might help if that requires us to change\nsome infrastructure here like hooking into executor at a higher level.\n\n> > * Should we refactor to borrow logic from ExecInsert so that it's less\n> > likely that we miss something in the future?\n>\n> Hooking into the executor at a higher level, possibly ExecInsert or ExecModifyTable would do a lot more than what logical replication currently does. If we also always used INSERT/UPDATE/DELETE statements and never COPY FROM statements, we might solve several problems at once, including honoring RLS policies and honoring rules defined for the target table on the subscriber side.\n>\n> Doing this would clearly be a major design change, and possibly one we do not want. Can we consider this out of scope?\n>\n\nI agree that if we want to do all of this then that would require a\nlot of changes. However, giving an error for RLS-enabled tables might\nalso be too restrictive. The few alternatives could be that (a) we\nallow subscription owners to be either have \"bypassrls\" attribute or\nthey could be superusers. (b) don't allow initial table_sync for rls\nenabled tables. (c) evaluate/analyze what is required to allow Copy\n From to start respecting RLS policies. (d) reject replicating any\nchanges to tables that have RLS enabled.\n\nI see that you are favoring (d) which clearly has merits like lesser\ncode/design change but not sure if that is the best way forward or we\ncan do something better than that either by following one of (a), (b),\n(c), or something less restrictive than (d).\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Mon, 29 Nov 2021 11:26:01 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Nov 28, 2021, at 9:56 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> In ExecUpdate(), we convert Update to DELETE+INSERT when the\n> partition constraint is failed whereas, on the subscriber-side, it\n> will simply fail in this case. It is not clear to me how that is\n> directly related to this patch but surely it will be a good\n> improvement on its own and might help if that requires us to change\n> some infrastructure here like hooking into executor at a higher level.\n\nI would rather get a fix for non-superuser subscription owners committed than expand the scope of work and have this patch linger until the v16 development cycle. This particular DELETE+INSERT problem sounds important but unrelated and out of scope.\n\n> I agree that if we want to do all of this then that would require a\n> lot of changes. However, giving an error for RLS-enabled tables might\n> also be too restrictive. The few alternatives could be that (a) we\n> allow subscription owners to be either have \"bypassrls\" attribute or\n> they could be superusers. (b) don't allow initial table_sync for rls\n> enabled tables. (c) evaluate/analyze what is required to allow Copy\n> From to start respecting RLS policies. (d) reject replicating any\n> changes to tables that have RLS enabled.\n> \n> I see that you are favoring (d) which clearly has merits like lesser\n> code/design change but not sure if that is the best way forward or we\n> can do something better than that either by following one of (a), (b),\n> (c), or something less restrictive than (d).\n\nI was favoring option (d) only when RLS policies exist for one or more of the target relations.\n\nSkipping the table_sync step while replicating tables that have RLS policies for subscriptions that are owned by users who lack bypassrls is interesting. If we make that work, it will be a more complete solution than option (d).\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 29 Nov 2021 08:26:38 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2021-11-29 at 08:26 -0800, Mark Dilger wrote:\n> > On Nov 28, 2021, at 9:56 PM, Amit Kapila <amit.kapila16@gmail.com>\n> > wrote:\n> > \n> > In ExecUpdate(), we convert Update to DELETE+INSERT when the\n> > partition constraint is failed whereas, on the subscriber-side, it\n> > will simply fail in this case.\n\nThank you, yes, that's the more important case.\n\n> This particular DELETE+INSERT problem sounds important but unrelated\n> and out of scope.\n\n+1\n\n> > I agree that if we want to do all of this then that would require a\n> > lot of changes. However, giving an error for RLS-enabled tables\n> > might\n> > also be too restrictive. The few alternatives could be that (a) we\n> > allow subscription owners to be either have \"bypassrls\" attribute\n> > or\n> > they could be superusers. (b) don't allow initial table_sync for\n> > rls\n> > enabled tables. (c) evaluate/analyze what is required to allow Copy\n> > From to start respecting RLS policies. (d) reject replicating any\n> > changes to tables that have RLS enabled.\n\nMaybe a combination?\n\nAllow subscriptions with copy_data=true iff the subscription owner is\nbypassrls or superuser. And then enforce RLS+WCO during\ninsert/update/delete.\n\nI don't think it's a big change (correct me if I'm wrong), and it\nallows good functionality now, and room to improve in the future if we\nwant to bring in more of ExecInsert into logical replication.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 29 Nov 2021 10:22:47 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2021-11-29 at 09:43 +0530, Amit Kapila wrote:\n> The first reason is that way it would be consistent with what we can\n> see while doing the operations from the backend.\n\nLogical replication is not interactive, so it doesn't seem quite the\nsame.\n\nIf you have a long running INSERT INTO SELECT or COPY FROM, the\npermission checks just happen at the beginning. As a user, it wouldn't\nsurprise me if logical replication was similar.\n\n> operation. Another reason is to make behavior predictable as users\n> can\n> always expect when exactly the privilege change will be reflected and\n> it won't depend on the number of changes in the transaction.\n\nThis patch does detect ownership changes more quickly (at the\ntransaction boundary) than the current code (only when it reloads for\nsome other reason). Transaction boundary seems like a reasonable time\nto detect the change to me.\n\nDetecting faster might be nice, but I don't have a strong opinion about\nit and I don't see why it necessarily needs to happen before this patch\ngoes in.\n\nAlso, do you think the cost of doing maybe_reread_subscription() per-\ntuple instead of per-transaction would be detectable? If we lock\nourselves into semantics that detect changes quickly, it will be harder\nto optimize the per-tuple path later.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 29 Nov 2021 11:26:01 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Nov 29, 2021 at 11:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Mon, 2021-11-29 at 08:26 -0800, Mark Dilger wrote:\n>\n> > > I agree that if we want to do all of this then that would require a\n> > > lot of changes. However, giving an error for RLS-enabled tables\n> > > might\n> > > also be too restrictive. The few alternatives could be that (a) we\n> > > allow subscription owners to be either have \"bypassrls\" attribute\n> > > or\n> > > they could be superusers. (b) don't allow initial table_sync for\n> > > rls\n> > > enabled tables. (c) evaluate/analyze what is required to allow Copy\n> > > From to start respecting RLS policies. (d) reject replicating any\n> > > changes to tables that have RLS enabled.\n>\n> Maybe a combination?\n>\n> Allow subscriptions with copy_data=true iff the subscription owner is\n> bypassrls or superuser. And then enforce RLS+WCO during\n> insert/update/delete.\n>\n\nYeah, that sounds reasonable to me.\n\n> I don't think it's a big change (correct me if I'm wrong),\n>\n\nYeah, I also don't think it should be a big change.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 30 Nov 2021 17:19:13 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Nov 30, 2021 at 12:56 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Mon, 2021-11-29 at 09:43 +0530, Amit Kapila wrote:\n> > The first reason is that way it would be consistent with what we can\n> > see while doing the operations from the backend.\n>\n> Logical replication is not interactive, so it doesn't seem quite the\n> same.\n>\n> If you have a long running INSERT INTO SELECT or COPY FROM, the\n> permission checks just happen at the beginning. As a user, it wouldn't\n> surprise me if logical replication was similar.\n>\n> > operation. Another reason is to make behavior predictable as users\n> > can\n> > always expect when exactly the privilege change will be reflected and\n> > it won't depend on the number of changes in the transaction.\n>\n> This patch does detect ownership changes more quickly (at the\n> transaction boundary) than the current code (only when it reloads for\n> some other reason). Transaction boundary seems like a reasonable time\n> to detect the change to me.\n>\n> Detecting faster might be nice, but I don't have a strong opinion about\n> it and I don't see why it necessarily needs to happen before this patch\n> goes in.\n>\n\nI think it would be better to do it before we allow subscription\nowners to be non-superusers.\n\n> Also, do you think the cost of doing maybe_reread_subscription() per-\n> tuple instead of per-transaction would be detectable?\n>\n\nYeah, it is possible that is why I suggested in one of the emails\nabove to allow changing the owners only for disabled subscriptions.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 30 Nov 2021 17:25:40 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\n> I think it would be better to do it before we allow subscription\n> owners to be non-superusers.\n\nThere are a couple other things to consider before allowing non-\nsuperusers to create subscriptions anyway. For instance, a non-\nsuperuser shouldn't be able to use a connection string that reads the\ncertificate file from the server unless they also have\npg_read_server_files privs.\n\n> Yeah, it is possible that is why I suggested in one of the emails\n> above to allow changing the owners only for disabled subscriptions.\n\nThe current patch detects the following cases at the transaction\nboundary:\n\n * ALTER SUBSCRIPTION ... OWNER TO ...\n * ALTER ROLE ... NOSUPERUSER\n * privileges revoked one way or another (aside from the RLS/WCO\nproblems, which will be fixed)\n\nIf we want to detect at row boundaries we need to capture all of those\ncases too, or else we're being inconsistent. The latter two cannot be\ntied to whether the subscription is disabled or not, so I don't think\nthat's a complete solution.\n\nHow about (as a separate patch) we just do maybe_reread_subscription()\nevery K operations within a transaction? That would speed up\npermissions errors if a revoke happens.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 30 Nov 2021 12:42:13 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\n> > I think it would be better to do it before we allow subscription\n> > owners to be non-superusers.\n>\n> There are a couple other things to consider before allowing non-\n> superusers to create subscriptions anyway. For instance, a non-\n> superuser shouldn't be able to use a connection string that reads the\n> certificate file from the server unless they also have\n> pg_read_server_files privs.\n>\n\nIsn't allowing to create subscriptions via non-superusers and allowing\nto change the owner two different things? I am under the impression\nthat the latter one is more towards allowing the workers to apply\nchanges with a non-superuser role.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Wed, 1 Dec 2021 19:06:17 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 1, 2021, at 5:36 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>> \n>> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\n>>> I think it would be better to do it before we allow subscription\n>>> owners to be non-superusers.\n>> \n>> There are a couple other things to consider before allowing non-\n>> superusers to create subscriptions anyway. For instance, a non-\n>> superuser shouldn't be able to use a connection string that reads the\n>> certificate file from the server unless they also have\n>> pg_read_server_files privs.\n>> \n> \n> Isn't allowing to create subscriptions via non-superusers and allowing\n> to change the owner two different things? I am under the impression\n> that the latter one is more towards allowing the workers to apply\n> changes with a non-superuser role.\n\nThe short-term goal is to have logical replication workers respect the privileges of the role which owns the subscription.\n\nThe long-term work probably includes creating a predefined role with permission to create subscriptions, and the ability to transfer those subscriptions to roles who might be neither superuser nor members of any particular predefined role; the idea being that logical replication subscriptions can be established without any superuser involvement, and may thereafter run without any special privilege.\n\nThe more recent patches on this thread are not as ambitious as the earlier patch-sets. We are no longer trying to support transferring subscriptions to non-superusers.\n\nRight now, on HEAD, if a subscription owner has superuser revoked, the subscription can continue to operate as superuser in so far as its replication actions are concerned. That seems like a pretty big security hole.\n\nThis patch mostly plugs that hole by adding permissions checks, so that a subscription owned by a role who has privileges revoked cannot (for the most part) continue to act under the old privileges.\n\nThere are two problematic edge cases that can occur after transfer of ownership. Remember, the new owner is required to be superuser for the transfer of ownership to occur.\n\n1) A subscription is transferred to a new owner, and the new owner then has privilege revoked.\n\n2) A subscription is transferred to a new owner, and then the old owner has privileges increased.\n\nIn both cases, a currently running logical replication worker may finish a transaction in progress acting with the current privileges of the old owner. The clearest solution is, as you suggest, to refuse transfer of ownership of subscriptions that are enabled.\n\nDoing so will create a failure case for REASSIGN OWNED BY. Will that be ok?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 1 Dec 2021 11:21:35 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Dec 2, 2021 at 12:51 AM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n>\n> > On Dec 1, 2021, at 5:36 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >\n> > On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\n> >>\n> >> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\n> >>> I think it would be better to do it before we allow subscription\n> >>> owners to be non-superusers.\n> >>\n> >> There are a couple other things to consider before allowing non-\n> >> superusers to create subscriptions anyway. For instance, a non-\n> >> superuser shouldn't be able to use a connection string that reads the\n> >> certificate file from the server unless they also have\n> >> pg_read_server_files privs.\n> >>\n> >\n> > Isn't allowing to create subscriptions via non-superusers and allowing\n> > to change the owner two different things? I am under the impression\n> > that the latter one is more towards allowing the workers to apply\n> > changes with a non-superuser role.\n>\n> The short-term goal is to have logical replication workers respect the privileges of the role which owns the subscription.\n>\n> The long-term work probably includes creating a predefined role with permission to create subscriptions, and the ability to transfer those subscriptions to roles who might be neither superuser nor members of any particular predefined role; the idea being that logical replication subscriptions can be established without any superuser involvement, and may thereafter run without any special privilege.\n>\n> The more recent patches on this thread are not as ambitious as the earlier patch-sets. We are no longer trying to support transferring subscriptions to non-superusers.\n>\n> Right now, on HEAD, if a subscription owner has superuser revoked, the subscription can continue to operate as superuser in so far as its replication actions are concerned. That seems like a pretty big security hole.\n>\n> This patch mostly plugs that hole by adding permissions checks, so that a subscription owned by a role who has privileges revoked cannot (for the most part) continue to act under the old privileges.\n>\n\nIf we want to maintain the property that subscriptions can only be\nowned by superuser for your first version then isn't a simple check\nlike ((!superuser()) for each of the operations is sufficient?\n\n> There are two problematic edge cases that can occur after transfer of ownership. Remember, the new owner is required to be superuser for the transfer of ownership to occur.\n>\n> 1) A subscription is transferred to a new owner, and the new owner then has privilege revoked.\n>\n> 2) A subscription is transferred to a new owner, and then the old owner has privileges increased.\n>\n\nIn (2), I am not clear what do you mean by \"the old owner has\nprivileges increased\"? If the owners can only be superusers then what\ndoes it mean to increase the privileges.\n\n> In both cases, a currently running logical replication worker may finish a transaction in progress acting with the current privileges of the old owner. The clearest solution is, as you suggest, to refuse transfer of ownership of subscriptions that are enabled.\n>\n> Doing so will create a failure case for REASSIGN OWNED BY. Will that be ok?\n>\n\nI think so. Do we see any problem with that? I think we have some\nfailure cases currently as well like \"All Tables Publication\" can only\nbe owned by superusers whereas ownership for others can be to\nnon-superusers and similarly we can't change ownership for pinned\nobjects. I think the case being discussed is not exactly the same but\nI am not able to see a problem with it.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 2 Dec 2021 14:59:46 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 2, 2021, at 1:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> If we want to maintain the property that subscriptions can only be\n> owned by superuser for your first version then isn't a simple check\n> like ((!superuser()) for each of the operations is sufficient?\n\nAs things stand today, nothing prevents a superuser subscription owner from having superuser revoked. The patch does nothing to change this.\n\n> In (2), I am not clear what do you mean by \"the old owner has\n> privileges increased\"? If the owners can only be superusers then what\n> does it mean to increase the privileges.\n\nThe old owner may have had privileges reduced (no superuser, only permission to write into a specific schema, etc.) and the subscription enabled only after those privilege reductions were put in place. This is a usage pattern this patch is intended to support, by honoring those privilege restrictions.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Fri, 3 Dec 2021 05:31:46 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Dec 3, 2021 at 10:37 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> > On Dec 2, 2021, at 1:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >\n> > If we want to maintain the property that subscriptions can only be\n> > owned by superuser for your first version then isn't a simple check\n> > like ((!superuser()) for each of the operations is sufficient?\n>\n> As things stand today, nothing prevents a superuser subscription owner from having superuser revoked. The patch does nothing to change this.\n>\n\nI understand that but won't that get verified when we look up the\ninformation in pg_authid as part of superuser() check?\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Mon, 6 Dec 2021 15:49:52 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n>>> If we want to maintain the property that subscriptions can only be\n>>> owned by superuser\n\nWe don't want to maintain such a property, or at least, that's not what I want. I don't think that's what Jeff wants, either.\n\nTo clarify, I'm not entirely sure how to interpret the verb \"maintain\" in your question, since before the patch the property does not exist, and after the patch, it continues to not exist. We could *add* such a property, of course, though this patch does not attempt any such thing.\n\n> I understand that but won't that get verified when we look up the\n> information in pg_authid as part of superuser() check?\n\nIf we added a superuser() check, then yes, but that would take things in a direction I do not want to go.\n\nAs I perceive the roadmap:\n\n1) Fix the current bug wherein subscription changes are applied with superuser force after the subscription owner has superuser privileges revoked.\n2) Allow the transfer of subscriptions to non-superuser owners.\n3) Allow the creation of subscriptions by non-superusers who are members of some as yet to be created predefined role, say \"pg_create_subscriptions\"\n\nI may be wrong, but it sounds like you interpret the intent of this patch as enforcing superuserness. That's not so. This patch intends to correctly handle the situation where a subscription is owned by a non-superuser (task 1, above) without going so far as creating new paths by which that situation could arise (tasks 2 and 3, above).\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 6 Dec 2021 07:56:56 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Le lundi 6 décembre 2021, 16:56:56 CET Mark Dilger a écrit :\n> > On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >>> If we want to maintain the property that subscriptions can only be\n> >>> owned by superuser\n> \n> We don't want to maintain such a property, or at least, that's not what I\n> want. I don't think that's what Jeff wants, either.\n\nThat's not what I want either: the ability to run and refresh subscriptions as \na non superuser is a desirable feature. \n\nThe REFRESH part was possible before PG 14, when it was allowed to run REFRESH \nin a function, which could be made to run as security definer. \n\n\n> As I perceive the roadmap:\n> \n> 1) Fix the current bug wherein subscription changes are applied with\n> superuser force after the subscription owner has superuser privileges\n> revoked. 2) Allow the transfer of subscriptions to non-superuser owners.\n> 3) Allow the creation of subscriptions by non-superusers who are members of\n> some as yet to be created predefined role, say \"pg_create_subscriptions\"\n\nThis roadmap seems sensible.\n\n-- \nRonan Dunklau\n\n\n\n\n","msg_date":"Tue, 07 Dec 2021 10:39:43 +0100","msg_from":"Ronan Dunklau <ronan.dunklau@aiven.io>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Dec 6, 2021 at 9:26 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n>\n> > On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >\n> >>> If we want to maintain the property that subscriptions can only be\n> >>> owned by superuser\n>\n> We don't want to maintain such a property, or at least, that's not what I want. I don't think that's what Jeff wants, either.\n>\n> To clarify, I'm not entirely sure how to interpret the verb \"maintain\" in your question, since before the patch the property does not exist, and after the patch, it continues to not exist. We could *add* such a property, of course, though this patch does not attempt any such thing.\n>\n\nOkay, let me try to explain again. Following is the text from docs\n[1]: \" (a) To create a subscription, the user must be a superuser. (b)\nThe subscription apply process will run in the local database with the\nprivileges of a superuser. (c) Privileges are only checked once at the\nstart of a replication connection. They are not re-checked as each\nchange record is read from the publisher, nor are they re-checked for\neach change when applied.\n\nMy understanding is that we want to improve what is written as (c)\nwhich I think is the same as what you mentioned later as \"Fix the\ncurrent bug wherein subscription changes are applied with superuser\nforce after the subscription owner has superuser privileges revoked.\".\nAm I correct till here? If so, I think what I am suggesting should fix\nthis with the assumption that we still want to follow (b) at least for\nthe first patch. One possibility is that our understanding of the\nfirst problem is the same but you want to allow apply worker running\neven when superuser privileges are revoked provided the user with\nwhich it is running has appropriate privileges on the objects being\naccessed by apply worker.\n\nWe will talk about other points of the roadmap you mentioned once our\nunderstanding for the first one matches.\n\n[1] - https://www.postgresql.org/docs/devel/logical-replication-security.html\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 7 Dec 2021 15:59:17 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 7, 2021, at 2:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> \n> Okay, let me try to explain again. Following is the text from docs\n> [1]: \" (a) To create a subscription, the user must be a superuser. (b)\n> The subscription apply process will run in the local database with the\n> privileges of a superuser. (c) Privileges are only checked once at the\n> start of a replication connection. They are not re-checked as each\n> change record is read from the publisher, nor are they re-checked for\n> each change when applied.\n> \n> My understanding is that we want to improve what is written as (c)\n> which I think is the same as what you mentioned later as \"Fix the\n> current bug wherein subscription changes are applied with superuser\n> force after the subscription owner has superuser privileges revoked.\".\n> Am I correct till here? If so, I think what I am suggesting should fix\n> this with the assumption that we still want to follow (b) at least for\n> the first patch.\n\nOk, that's a point of disagreement. I was trying to fix both (b) and (c) in the first patch.\n\n> One possibility is that our understanding of the\n> first problem is the same but you want to allow apply worker running\n> even when superuser privileges are revoked provided the user with\n> which it is running has appropriate privileges on the objects being\n> accessed by apply worker.\n\nCorrect, that's what I'm trying to make safe.\n\n> We will talk about other points of the roadmap you mentioned once our\n> understanding for the first one matches.\n\nI am happy to have an off-list phone call with you, if you like.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 7 Dec 2021 06:55:51 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Dec 7, 2021 at 8:25 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n>\n> > On Dec 7, 2021, at 2:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >\n> > Okay, let me try to explain again. Following is the text from docs\n> > [1]: \" (a) To create a subscription, the user must be a superuser. (b)\n> > The subscription apply process will run in the local database with the\n> > privileges of a superuser. (c) Privileges are only checked once at the\n> > start of a replication connection. They are not re-checked as each\n> > change record is read from the publisher, nor are they re-checked for\n> > each change when applied.\n> >\n> > My understanding is that we want to improve what is written as (c)\n> > which I think is the same as what you mentioned later as \"Fix the\n> > current bug wherein subscription changes are applied with superuser\n> > force after the subscription owner has superuser privileges revoked.\".\n> > Am I correct till here? If so, I think what I am suggesting should fix\n> > this with the assumption that we still want to follow (b) at least for\n> > the first patch.\n>\n> Ok, that's a point of disagreement. I was trying to fix both (b) and (c) in the first patch.\n>\n\nBut, I think as soon as we are trying to fix (b), we seem to be\nallowing non-superusers to apply changes. If we want to do that then\nwe should be even allowed to change the owners to non-superusers. I\nwas thinking of the below order:\n1. First fix (c) from the above description \"Privileges are only\nchecked once at the start of a replication connection.\"\n2A. Allow the transfer of subscriptions to non-superuser owners. This\nwill be allowed only on disabled subscriptions to make this action\npredictable.\n2B. The apply worker should be able to apply the changes provided the\nuser has appropriate privileges on the objects being accessed by apply\nworker.\n3) Allow the creation of subscriptions by non-superusers who are\nmembers of some as yet to be created predefined role, say\n\"pg_create_subscriptions\"\n\nWe all seem to agree that (3) can be done later as an independent\nproject. 2A, 2B can be developed as separate patches but they need to\nbe considered together for commit. After 2A, 2B, the first one (1)\nwon't be required so, in fact, we can just ignore (1) but the only\nbenefit I see is that if we stuck with some design problem during the\ndevelopment of 2A, 2B, we would have at least something better than\nwhat we have now.\n\nYou seem to be indicating let's do 2B first as that will anyway be\nused later after 2A and 1 won't be required if we do that. I see that\nbut I personally feel either we should follow 1, 2(A, B) or just do\n2(A, B).\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 9 Dec 2021 10:28:24 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > This patch does detect ownership changes more quickly (at the\n> > transaction boundary) than the current code (only when it reloads for\n> > some other reason). Transaction boundary seems like a reasonable time\n> > to detect the change to me.\n> >\n> > Detecting faster might be nice, but I don't have a strong opinion about\n> > it and I don't see why it necessarily needs to happen before this patch\n> > goes in.\n>\n> I think it would be better to do it before we allow subscription\n> owners to be non-superusers.\n\nI think it would be better not to ever do it at any time.\n\nIt seems like a really bad idea to me to change the run-as user in the\nmiddle of a transaction. That seems prone to producing all sorts of\nconfusing behavior that's hard to understand, and hard to test. So\nwhat are we to do if a change occurs mid-transaction? I think we can\neither finish replicating the current transaction and then switch to\nthe new owner for the next transaction, or we could abort the current\nattempt to replicate the transaction and retry the whole transaction\nwith the new run-as user. My guess is that most users would prefer the\nformer behavior to the latter.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 9 Dec 2021 10:41:21 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Dec 8, 2021 at 11:58 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> But, I think as soon as we are trying to fix (b), we seem to be\n> allowing non-superusers to apply changes. If we want to do that then\n> we should be even allowed to change the owners to non-superusers. I\n> was thinking of the below order:\n> 1. First fix (c) from the above description \"Privileges are only\n> checked once at the start of a replication connection.\"\n> 2A. Allow the transfer of subscriptions to non-superuser owners. This\n> will be allowed only on disabled subscriptions to make this action\n> predictable.\n> 2B. The apply worker should be able to apply the changes provided the\n> user has appropriate privileges on the objects being accessed by apply\n> worker.\n> 3) Allow the creation of subscriptions by non-superusers who are\n> members of some as yet to be created predefined role, say\n> \"pg_create_subscriptions\"\n>\n> We all seem to agree that (3) can be done later as an independent\n> project. 2A, 2B can be developed as separate patches but they need to\n> be considered together for commit. After 2A, 2B, the first one (1)\n> won't be required so, in fact, we can just ignore (1) but the only\n> benefit I see is that if we stuck with some design problem during the\n> development of 2A, 2B, we would have at least something better than\n> what we have now.\n>\n> You seem to be indicating let's do 2B first as that will anyway be\n> used later after 2A and 1 won't be required if we do that. I see that\n> but I personally feel either we should follow 1, 2(A, B) or just do\n> 2(A, B).\n\n1 and 2B seem to require changing the same code, or related code. 1A\nseems to require a completely different set of changes. If I'm right\nabout that, it seems like a good reason for doing 1+2B first and\nleaving 2A for a separate patch.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 9 Dec 2021 10:47:03 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 9, 2021, at 7:41 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n>>> This patch does detect ownership changes more quickly (at the\n>>> transaction boundary) than the current code (only when it reloads for\n>>> some other reason). Transaction boundary seems like a reasonable time\n>>> to detect the change to me.\n>>> \n>>> Detecting faster might be nice, but I don't have a strong opinion about\n>>> it and I don't see why it necessarily needs to happen before this patch\n>>> goes in.\n>> \n>> I think it would be better to do it before we allow subscription\n>> owners to be non-superusers.\n> \n> I think it would be better not to ever do it at any time.\n> \n> It seems like a really bad idea to me to change the run-as user in the\n> middle of a transaction.\n\nI agree. We allow SET ROLE inside transactions, but faking one on the subscriber seems odd. No such role change was performed on the publisher side, nor is there a principled reason for assuming the old run-as role has membership in the new run-as role, so we'd be pretending to do something that might otherwise be impossible.\n\nThere was some discussion off-list about having the apply worker take out a lock on its subscription, thereby blocking ownership changes mid-transaction. I coded that and it seems to work fine, but I have a hard time seeing how the lock traffic would be worth expending. Between (a) changing roles mid-transaction, and (b) locking the subscription for each transaction, I'd prefer to do neither, but (b) seems far better than (a). Thoughts?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Thu, 9 Dec 2021 09:22:07 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Dec 9, 2021, at 7:47 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> 1 and 2B seem to require changing the same code, or related code. 1A\n> seems to require a completely different set of changes. If I'm right\n> about that, it seems like a good reason for doing 1+2B first and\n> leaving 2A for a separate patch.\n\nThere are unresolved problems with 2A and 3 which were discussed upthread. I don't want to include fixes for them in this patch, as it greatly expands the scope of this patch, and is a logically separate effort. We can come back to those problems after this first patch is committed.\n\n\nSpecifically, a non-superuser owner can perform ALTER SUBSCRIPTION and do things that are morally equivalent to creating a new subscription. This is problematic where things like the connection string are concerned, because it means the non-superuser owner can connect out to entirely different servers, without any access control checks to make sure the owner should be able to connect to these servers.\n\nThis problem already exists, right now. I'm not fixing it in this first patch, but I'm also not making it any worse.\n\nThe solution Jeff Davis proposed seems right to me. We change subscriptions to use a foreign server rather than a freeform connection string. When creating or altering a subscription, the role performing the action must have privileges on any foreign server they use.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Thu, 9 Dec 2021 09:48:59 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Dec 9, 2021 at 10:52 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> > On Dec 9, 2021, at 7:41 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> >\n> > On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >>> This patch does detect ownership changes more quickly (at the\n> >>> transaction boundary) than the current code (only when it reloads for\n> >>> some other reason). Transaction boundary seems like a reasonable time\n> >>> to detect the change to me.\n> >>>\n> >>> Detecting faster might be nice, but I don't have a strong opinion about\n> >>> it and I don't see why it necessarily needs to happen before this patch\n> >>> goes in.\n> >>\n> >> I think it would be better to do it before we allow subscription\n> >> owners to be non-superusers.\n> >\n> > I think it would be better not to ever do it at any time.\n> >\n> > It seems like a really bad idea to me to change the run-as user in the\n> > middle of a transaction.\n>\n> I agree. We allow SET ROLE inside transactions, but faking one on the subscriber seems odd. No such role change was performed on the publisher side, nor is there a principled reason for assuming the old run-as role has membership in the new run-as role, so we'd be pretending to do something that might otherwise be impossible.\n>\n> There was some discussion off-list about having the apply worker take out a lock on its subscription, thereby blocking ownership changes mid-transaction. I coded that and it seems to work fine, but I have a hard time seeing how the lock traffic would be worth expending. Between (a) changing roles mid-transaction, and (b) locking the subscription for each transaction, I'd prefer to do neither, but (b) seems far better than (a). Thoughts?\n>\n\nYeah, to me also (b) sounds better than (a). However, a few points\nthat we might want to consider in that regard are as follows: 1.\nlocking the subscription for each transaction will add new blocking\nareas considering we acquire AccessExclusiveLock to change any\nproperty of subscription. But as Alter Subscription won't be that\nfrequent operation it might be acceptable. 2. It might lead to adding\nsome cost to small transactions but not sure if that will be\nnoticeable. 3. Tomorrow, if we want to make the apply-process parallel\n(IIRC, we do have the patch for that somewhere in archives) especially\nfor large in-progress transactions then this locking will have\nadditional blocking w.r.t Altering Subscription. But again, this also\nmight be acceptable.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 10 Dec 2021 09:45:08 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> Yeah, to me also (b) sounds better than (a). However, a few points\n> that we might want to consider in that regard are as follows: 1.\n> locking the subscription for each transaction will add new blocking\n> areas considering we acquire AccessExclusiveLock to change any\n> property of subscription. But as Alter Subscription won't be that\n> frequent operation it might be acceptable.\n\nThe problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\nIt's the cost of locking and unlocking the relation for every\ntransaction we apply. Suppose it's a pgbench-type workload with a\nsingle UPDATE per transaction. You've just limited the maximum\npossible apply speed to about, I think, 30,000 transactions per second\nno matter how many parallel workers you use, because that's how fast\nthe lock manager is (or was, unless newer hardware or newer PG\nversions have changed things in a way I don't know about). That seems\nlike a poor idea. There's nothing wrong with noticing changes at the\nnext transaction boundary, as long as we document it. So why would we\nincur a possibly-significant performance cost to provide a stricter\nguarantee?\n\nI bet users wouldn't even like this behavior. It would mean that if\nyou are replicating a long-running transaction, an ALTER SUBSCRIPTION\ncommand might block for a long time until replication of that\ntransaction completes. I have a hard time understanding why anyone\nwould consider that an improvement.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 10 Dec 2021 09:09:26 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 12/10/21 09:09, Robert Haas wrote:\n> On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> Yeah, to me also (b) sounds better than (a). However, a few points\n>> that we might want to consider in that regard are as follows: 1.\n>> locking the subscription for each transaction will add new blocking\n>> areas considering we acquire AccessExclusiveLock to change any\n>> property of subscription. But as Alter Subscription won't be that\n>> frequent operation it might be acceptable.\n> The problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\n> It's the cost of locking and unlocking the relation for every\n> transaction we apply. Suppose it's a pgbench-type workload with a\n> single UPDATE per transaction. You've just limited the maximum\n> possible apply speed to about, I think, 30,000 transactions per second\n> no matter how many parallel workers you use, because that's how fast\n> the lock manager is (or was, unless newer hardware or newer PG\n> versions have changed things in a way I don't know about). That seems\n> like a poor idea. There's nothing wrong with noticing changes at the\n> next transaction boundary, as long as we document it. So why would we\n> incur a possibly-significant performance cost to provide a stricter\n> guarantee?\n>\n> I bet users wouldn't even like this behavior. It would mean that if\n> you are replicating a long-running transaction, an ALTER SUBSCRIPTION\n> command might block for a long time until replication of that\n> transaction completes. I have a hard time understanding why anyone\n> would consider that an improvement.\n>\n\n\n+1\n\n\nI think noticing changes at the transaction boundary is perfectly\nacceptable.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Fri, 10 Dec 2021 10:20:02 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Dec 10, 2021 at 7:39 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > Yeah, to me also (b) sounds better than (a). However, a few points\n> > that we might want to consider in that regard are as follows: 1.\n> > locking the subscription for each transaction will add new blocking\n> > areas considering we acquire AccessExclusiveLock to change any\n> > property of subscription. But as Alter Subscription won't be that\n> > frequent operation it might be acceptable.\n>\n> The problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\n> It's the cost of locking and unlocking the relation for every\n> transaction we apply.\n>\n\nThis point is not clear to me as we are already locking the relation\nwhile applying changes. I think here additional cost is to lock a\nparticular subscription as well in addition to the relation on which\nwe are going to perform apply. I agree that has a cost and that is why\nI mentioned it as one of the points above and then also the\nconcurrency effect as you also noted could make this idea moot.\n\n> Suppose it's a pgbench-type workload with a\n> single UPDATE per transaction. You've just limited the maximum\n> possible apply speed to about, I think, 30,000 transactions per second\n> no matter how many parallel workers you use, because that's how fast\n> the lock manager is (or was, unless newer hardware or newer PG\n> versions have changed things in a way I don't know about). That seems\n> like a poor idea. There's nothing wrong with noticing changes at the\n> next transaction boundary, as long as we document it.\n>\n\nIf we want to just document this then I think we should also keep in\nmind that these could be N transactions as well if say tomorrow we\nhave N parallel apply workers applying the N transactions in parallel.\nI think it might also be possible that RLS policies won't be applied\nfor initial table sync whereas those will be applied for later changes\neven though the ownership has changed before both operations and one\nof those happens to miss it. If that is possible, then it might be\nbetter to avoid the same as it could appear inconsistent as mentioned\nby Mark [1] as well. Now, it might be possible to avoid this by\nimplementation or we can say that we don't care about this or just\ndocument it. But it seems to me that if we have some way to detect the\nchange of ownership at each operation level then no such possibilities\nwould arise.\n\nThe other alternative we discussed was to allow a change of ownership\non disabled subscriptions that way the apply behavior will always be\npredictable.\n\nThere is clearly a merit in noticing the change of ownership at\ntransaction boundary but just wanted to consider other possibilities.\nIt could be that detecting at transaction-boundary is the best we can\ndo but I think there is no harm in considering other possibilities.\n\n> So why would we\n> incur a possibly-significant performance cost to provide a stricter\n> guarantee?\n>\n> I bet users wouldn't even like this behavior. It would mean that if\n> you are replicating a long-running transaction, an ALTER SUBSCRIPTION\n> command might block for a long time until replication of that\n> transaction completes.\n>\n\nAgreed and if we decide to lock the subscription during the initial\ntable sync phase then that could also take a long time for which again\nusers might not be happy.\n\n[1] - https://www.postgresql.org/message-id/FE7D7024-6723-4ACB-82AB-94F6A194BE0D%40enterprisedb.com\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Sat, 11 Dec 2021 10:25:36 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"> On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> We need to do permission checking for WITH CHECK OPTION and RLS. The\n> patch right now allows the subscription to write data that an RLS\n> policy forbids.\n\nVersion 4 of the patch, attached, no longer allows RLS to be circumvented, but does so in a course-grained fashion. If the target table has row-level security policies which are enforced against the subscription owner, the replication draws an error, much as with a permissions failure. This seems sufficient for now, as superusers, roles with bypassrls, and target table owners should be able to replicate as before. We may want to revisit this later, perhaps if/when we address your ExecInsert question, below.\n\n> \n> A couple other points:\n> \n> * We shouldn't refer to the behavior of previous versions in the docs\n> unless there's a compelling reason\n\nFixed.\n\n> * Do we need to be smarter about partitioned tables, where an insert\n> can turn into an update?\n\nIndeed, the logic of apply_handle_tuple_routing() required a bit of refactoring. Fixed in v4.\n\n> * Should we refactor to borrow logic from ExecInsert so that it's less\n> likely that we miss something in the future?\n\nLet's just punt on this for now.\n\n\n\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Wed, 15 Dec 2021 12:23:02 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Dec 16, 2021 at 1:53 AM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n>\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> >\n> > We need to do permission checking for WITH CHECK OPTION and RLS. The\n> > patch right now allows the subscription to write data that an RLS\n> > policy forbids.\n>\n> Version 4 of the patch, attached.\n>\n\nFor Update/Delete, we do read the table first via\nFindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\nbefore that?\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Sat, 8 Jan 2022 12:27:21 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\n> For Update/Delete, we do read the table first via\n> FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\n> before that?\n\nIf it's logically an update/delete, then I think ACL_UPDATE/DELETE is\nthe right one to check. Do you have a different opinion?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Fri, 07 Jan 2022 23:31:06 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2021-12-15 at 12:23 -0800, Mark Dilger wrote:\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\n> > \n> > We need to do permission checking for WITH CHECK OPTION and RLS.\n> > The\n> > patch right now allows the subscription to write data that an RLS\n> > policy forbids.\n> \n> Version 4 of the patch, attached, no longer allows RLS to be\n> circumvented, but does so in a course-grained fashion.\n\nCommitted.\n\nI tried to do some performance testing to see if there was any impact\nof the extra catalog + ACL checks. Logical replication seems slow\nenough -- something like 3X slower than local inserts -- that it didn't\nseem to make a difference.\n\nTo test it, I did the following:\n 1. sent a SIGSTOP to the logical apply worker\n 2. loaded more data in publisher\n 3. made the subscriber a sync replica\n 4. timed the following:\n a. sent a SIGCONT to the logical apply worker\n b. insert a single tuple on the publisher side\n c. wait for the insert to return, indicating that logical\n replication is done up to that point\n\nDoes anyone have a better way to measure logical replication\nperformance?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Fri, 07 Jan 2022 23:38:31 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Jan 8, 2022 at 1:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\n> > For Update/Delete, we do read the table first via\n> > FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\n> > before that?\n>\n> If it's logically an update/delete, then I think ACL_UPDATE/DELETE is\n> the right one to check. Do you have a different opinion?\n>\n\nBut shouldn't we do it the first time before accessing the table?\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Sat, 8 Jan 2022 15:35:08 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, 2022-01-08 at 15:35 +0530, Amit Kapila wrote:\n> On Sat, Jan 8, 2022 at 1:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > \n> > On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\n> > > For Update/Delete, we do read the table first via\n> > > FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\n> > > before that?\n> > \n> > If it's logically an update/delete, then I think ACL_UPDATE/DELETE\n> > is\n> > the right one to check. Do you have a different opinion?\n> > \n> \n> But shouldn't we do it the first time before accessing the table?\n\nI'm not sure I follow the reasoning. Are you saying that, to logically\nreplay a simple DELETE, the subscription owner should have SELECT\nprivileges on the destination table?\n\nIs there a way that a subscription owner could somehow exploit a DELETE\nprivilege to see the contents of a table on which they have no SELECT\nprivileges? Or is it purely an internal read, which is necessary for\nany ordinary local DELETE/UPDATE anyway?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sat, 08 Jan 2022 09:14:59 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Jeff Davis <pgsql@j-davis.com> writes:\n> I'm not sure I follow the reasoning. Are you saying that, to logically\n> replay a simple DELETE, the subscription owner should have SELECT\n> privileges on the destination table?\n\nWe consider that DELETE WHERE <condition> requires SELECT privilege\non the column(s) read by the <condition>. I suppose that the point\nhere is to enforce the same privilege checks that occur in normal\nSQL operation, so yes.\n\n> Is there a way that a subscription owner could somehow exploit a DELETE\n> privilege to see the contents of a table on which they have no SELECT\n> privileges?\n\nBEGIN;\nDELETE FROM tab WHERE col = 'foo';\n-- note deletion count\nROLLBACK;\n\nNow you have some information about whether \"col\" contains 'foo'.\nAdmittedly, it might be a pretty low-bandwidth way to extract data,\nbut we still regard it as a privilege issue.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sat, 08 Jan 2022 12:37:49 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"... btw, I'd like to complain that this new test script consumes\na completely excessive amount of time. On my fairly-new primary\nworkstation:\n\n[12:48:00] t/027_nosuperuser.pl ............... ok 22146 ms ( 0.02 usr 0.00 sys + 1.12 cusr 0.95 csys = 2.09 CPU)\n\nThe previously-slowest script in the subscription suite is\n\n[12:48:23] t/100_bugs.pl ...................... ok 7048 ms ( 0.00 usr 0.00 sys + 2.85 cusr 0.99 csys = 3.84 CPU)\n\nand the majority of the scripts clock in at more like 2 to 4 seconds.\nSo I don't think I'm out of line in saying that this test is consuming\nan order of magnitude more time than is justified. I do not wish to\nsee this much time added to every check-world run till kingdom come\nfor this one feature/issue.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sat, 08 Jan 2022 12:57:18 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, 2022-01-08 at 12:57 -0500, Tom Lane wrote:\n> ... btw, I'd like to complain that this new test script consumes\n> a completely excessive amount of time.\n\nShould be fixed now; I brought the number of tests down from 100 to 14.\nIt's not running in 2 seconds on my machine, but it's in line with the\nother tests.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sun, 09 Jan 2022 10:09:03 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Jeff Davis <pgsql@j-davis.com> writes:\n> On Sat, 2022-01-08 at 12:57 -0500, Tom Lane wrote:\n>> ... btw, I'd like to complain that this new test script consumes\n>> a completely excessive amount of time.\n\n> Should be fixed now; I brought the number of tests down from 100 to 14.\n> It's not running in 2 seconds on my machine, but it's in line with the\n> other tests.\n\nThanks, I appreciate that.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sun, 09 Jan 2022 14:10:22 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Jan 8, 2022 at 2:38 AM Jeff Davis <pgsql@j-davis.com> wrote:\n> Committed.\n\nI was just noticing that what was committed here didn't actually fix\nthe problem implied by the subject line. That is, non-superuser still\ncan't own subscriptions. To put that another way, there's no way for\nthe superuser to delegate the setup and administration of logical\nreplication to a non-superuser. That's a bummer.\n\nReading the thread, I'm not quite sure why we seemingly did all the\npreparatory work and then didn't actually fix the problem. It was\npreviously proposed that we introduce a new predefined role\npg_create_subscriptions and allow users who have the privileges of\nthat predefined role to create and alter subscriptions. There are a\nfew issues with that which, however, seem fairly solvable to me:\n\n1. Jeff pointed out that if you supply a connection string that is\ngoing to try to access local files, you'd better have\npg_read_server_files, or else we should not let you use that\nconnection string. I guess that's mostly a function of which\nparameters you specify, e.g. passfile, sslcert, sslkey, though maybe\nfor host it depends on whether the value starts with a slash. We might\nneed to think a bit here to make sure we get the rules right but it\nseems like a pretty solvable problem.\n\n2. There was also quite a bit of discussion of what to do if a user\nwho was previously eligible to own a subscription ceases to be\neligible, in particular around a superuser who is made into a\nnon-superuser, but the same problem would apply if you had\npg_create_subscriptions or pg_read_server_files and then lost it. My\nvote is to not worry about it too much. Specifically, I think we\nshould certainly check whether the user has permission to create a\nsubscription before letting them do so, but we could handle the case\nwhere the user already owns a subscription and tries to modify it by\neither allowing or denying the operation and I think either of those\nwould be fine. I even think we could do one of those in some cases and\nthe other in other cases and as long as there is some principle to the\nthing, it's fine. I argue that it's not a normal configuration and\ntherefore it doesn't have to work in a particularly useful way. It\nshouldn't break the world in some horrendous way, but that's about as\ngood as it needs to be. I'd argue for example that DROP SUBSCRIPTION\ncould just check whether you own the object, and that ALTER\nSUBSCRIPTION could check whether you own the object and, if you're\nchanging the connection string, also whether you would have privileges\nto set that new connection string on a new subscription.\n\n3. There was a bit of discussion of maybe wanting to allow users to\ncreate subscriptions with some connection strings but not others,\nperhaps by having some kind of intermediate object that owns the\nconnection string and is owned by a superuser or someone with lots of\nprivileges, and then letting a less-privileged user point a\nsubscription at that object. I agree that might be useful to somebody,\nbut I don't see why it's a hard requirement to get anything at all\ndone here. Right now, a subscription contains a connection string\ndirectly. If in the future someone wants to introduce a CREATE\nREPLICATION DESTINATION command (or whatever) and have a way to point\na subscription at a replication destination rather than a connection\nstring directly, cool. Or if someone wants to wire this into CREATE\nSERVER somehow, also cool. But if you don't care about restricting\nwhich IPs somebody can try to access by providing a connection string\nof their choice, then you would be happy if we just did something\nsimple here and left this problem for another day.\n\nI am very curious to know (a) why work on this was abandoned (perhaps\nthe answer is just lack of round tuits, in which case there is no more\nto be said), and (b) what people think of (1)-(3) above, and (c)\nwhether anyone knows of further problems that need to be considered\nhere.\n\nThanks,\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 18 Jan 2023 14:38:21 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 18, 2023, at 11:38 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> I was just noticing that what was committed here didn't actually fix\n> the problem implied by the subject line. That is, non-superuser still\n> can't own subscriptions.\n\nNot so. They can. See src/test/subscription/027_nosuperuser.pl\n\n> To put that another way, there's no way for\n> the superuser to delegate the setup and administration of logical\n> replication to a non-superuser.\n\nTrue.\n\n> That's a bummer.\n\nAlso true.\n\n> Reading the thread, I'm not quite sure why we seemingly did all the\n> preparatory work and then didn't actually fix the problem.\n\nPrior to the patch, if a superuser created a subscription, then later was demoted to non-superuser, the subscription apply workers still applied the changes with superuser force. So creating a superuser Alice, letting Alice create a subscription, then revoking superuser from Alice didn't accomplish anything interesting. But after the patch, it does. The superuser can now create non-superuser subscriptions. (I'm not sure this ability is well advertised.) But the problem of non-superuser roles creating non-superuser subscriptions is not solved.\n\nFrom a security perspective, the bit that was solved may be the more important part; from a usability perspective, perhaps not.\n\n> It was\n> previously proposed that we introduce a new predefined role\n> pg_create_subscriptions and allow users who have the privileges of\n> that predefined role to create and alter subscriptions. There are a\n> few issues with that which, however, seem fairly solvable to me:\n> \n> 1. Jeff pointed out that if you supply a connection string that is\n> going to try to access local files, you'd better have\n> pg_read_server_files, or else we should not let you use that\n> connection string. I guess that's mostly a function of which\n> parameters you specify, e.g. passfile, sslcert, sslkey, though maybe\n> for host it depends on whether the value starts with a slash. We might\n> need to think a bit here to make sure we get the rules right but it\n> seems like a pretty solvable problem.\n> \n> 2. There was also quite a bit of discussion of what to do if a user\n> who was previously eligible to own a subscription ceases to be\n> eligible, in particular around a superuser who is made into a\n> non-superuser, but the same problem would apply if you had\n> pg_create_subscriptions or pg_read_server_files and then lost it. My\n> vote is to not worry about it too much. Specifically, I think we\n> should certainly check whether the user has permission to create a\n> subscription before letting them do so, but we could handle the case\n> where the user already owns a subscription and tries to modify it by\n> either allowing or denying the operation and I think either of those\n> would be fine. I even think we could do one of those in some cases and\n> the other in other cases and as long as there is some principle to the\n> thing, it's fine. I argue that it's not a normal configuration and\n> therefore it doesn't have to work in a particularly useful way. It\n> shouldn't break the world in some horrendous way, but that's about as\n> good as it needs to be. I'd argue for example that DROP SUBSCRIPTION\n> could just check whether you own the object, and that ALTER\n> SUBSCRIPTION could check whether you own the object and, if you're\n> changing the connection string, also whether you would have privileges\n> to set that new connection string on a new subscription.\n> \n> 3. There was a bit of discussion of maybe wanting to allow users to\n> create subscriptions with some connection strings but not others,\n> perhaps by having some kind of intermediate object that owns the\n> connection string and is owned by a superuser or someone with lots of\n> privileges, and then letting a less-privileged user point a\n> subscription at that object. I agree that might be useful to somebody,\n> but I don't see why it's a hard requirement to get anything at all\n> done here. Right now, a subscription contains a connection string\n> directly. If in the future someone wants to introduce a CREATE\n> REPLICATION DESTINATION command (or whatever) and have a way to point\n> a subscription at a replication destination rather than a connection\n> string directly, cool. Or if someone wants to wire this into CREATE\n> SERVER somehow, also cool. But if you don't care about restricting\n> which IPs somebody can try to access by providing a connection string\n> of their choice, then you would be happy if we just did something\n> simple here and left this problem for another day.\n> \n> I am very curious to know (a) why work on this was abandoned (perhaps\n> the answer is just lack of round tuits, in which case there is no more\n> to be said)\n\nMostly, it was a lack of round-tuits. After the patch was committed, I quickly switched my focus elsewhere.\n\n> , and (b) what people think of (1)-(3) above\n\nThere are different ways of solving (1), and Jeff and I discussed them in Dec 2021. My recollection was that idea (3) was the cleanest. Other ideas might be simpler than (3), or they may just appear simpler but in truth turn into a can of worms. I don't know, since I never went as far as trying to implement either approach.\n\nIdea (2) seems to contemplate non-superuser subscription owners as a theoretical thing, but it's quite real already. Again, see 027_nosuperuser.pl.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 18 Jan 2023 12:26:43 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Jan 18, 2023 at 3:26 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> Prior to the patch, if a superuser created a subscription, then later was demoted to non-superuser, the subscription apply workers still applied the changes with superuser force. So creating a superuser Alice, letting Alice create a subscription, then revoking superuser from Alice didn't accomplish anything interesting. But after the patch, it does. The superuser can now create non-superuser subscriptions. (I'm not sure this ability is well advertised.) But the problem of non-superuser roles creating non-superuser subscriptions is not solved.\n\nAh, OK, thanks for the clarification!\n\n> There are different ways of solving (1), and Jeff and I discussed them in Dec 2021. My recollection was that idea (3) was the cleanest. Other ideas might be simpler than (3), or they may just appear simpler but in truth turn into a can of worms. I don't know, since I never went as far as trying to implement either approach.\n>\n> Idea (2) seems to contemplate non-superuser subscription owners as a theoretical thing, but it's quite real already. Again, see 027_nosuperuser.pl.\n\nI think the solution to the problem of a connection string trying to\naccess local files is to just look at the connection string, decide\nwhether it does that, and if yes, require the owner to have\npg_read_server_files as well as pg_create_subscription. (3) is about\ncreating some more sophisticated and powerful solution to that\nproblem, but that seems like a nice-to-have, not something essential,\nand a lot more complicated to implement.\n\nI guess what I listed as (2) is not relevant since I didn't understand\ncorrectly what the current state of things is.\n\nUnless I'm missing something, it seems like this could be a quite small patch.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 18 Jan 2023 15:51:08 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> Unless I'm missing something, it seems like this could be a quite small patch.\n\nI didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\n \n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 18 Jan 2023 12:58:26 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Jan 18, 2023 at 3:58 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> > On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\n> >\n> > Unless I'm missing something, it seems like this could be a quite small patch.\n>\n> I didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\n\nI wouldn't be OK with writing our own connection string parser for\nthis purpose, but using PQconninfoParse seems OK. We still have to\nembed knowledge of which connection string parameters can trigger\nlocal file access, but that doesn't seem like a massive problem to me.\nIf we already had (or have) that logic someplace else, it would\nprobably make sense to reuse it, but if we don't, writing new logic\ndoesn't seem prohibitively scary. I'm not 100% confident of my ability\nto get those rules right on the first try, but I feel like whatever\nproblems are there are just bugs that can be fixed with a few lines of\ncode changes. The basic idea that by looking at which connection\nstring properties are set we can tell what kinds of things the\nconnection string is going to do seems sound to me.\n\nIf there's some reason that it isn't, that would be good to discover\nnow rather than later.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 19 Jan 2023 10:45:35 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-01-18 at 14:38 -0500, Robert Haas wrote:\n> I was just noticing that what was committed here didn't actually fix\n> the problem implied by the subject line. That is, non-superuser still\n> can't own subscriptions. To put that another way, there's no way for\n> the superuser to delegate the setup and administration of logical\n> replication to a non-superuser. That's a bummer.\n\nRight, though as Mark pointed out, it does accomplish something even if\nit's a bit unsatisfying. We could certainly do better here.\n\n> 2. There was also quite a bit of discussion of what to do if a user\n> who was previously eligible to own a subscription ceases to be\n> eligible, in particular around a superuser who is made into a\n> non-superuser, but the same problem would apply\n\nCorrect, that's not a new problem, but exists in only a few places now.\nOur privilege system is focused on \"what action can the user take right\nnow?\", and gets weirder when it comes to object ownership, which is a\nmore permanent thing.\n\nExtending that system to a subscription object, which has its own\ncapabilities including a long-lived process, is cause for some\nhesitation. I agree it's not necessarily a blocker.\n\n> 3. There was a bit of discussion of maybe wanting to allow users to\n> create subscriptions with some connection strings but not others,\n\nThis was an alternative to trying to sanitize connection strings,\nbecause it's a bit difficult to reason about what might be \"safe\"\nconnection strings for a non-superuser, because it's environment-\ndependent. But if we do identify a reasonable set of sanitization\nrules, we can proceed without 3.\n\n> I am very curious to know (a) why work on this was abandoned (perhaps\n> the answer is just lack of round tuits, in which case there is no\n> more\n> to be said), and (b) what people think of (1)-(3) above, and (c)\n> whether anyone knows of further problems that need to be considered\n> here.\n\n(a) Mostly round-tuits. There are problems and questions; but there are\nwith any work, and they could be solved. Or, if they don't turn out to\nbe terribly serious, we could ignore them.\n\n(b) When I pick this up again I would be inclined towards the\nfollowing: try to solve 4-5 (listed below) first, which are\nindependently useful; then look at both 1 and 3 to see which one\npresents an agreeable solution faster. I'll probably ignore 2 because I\ncouldn't get agreement the last time around (I think Mark objected to\nthe idea of denying a drop in privileges).\n\n(c) Let me add:\n\n4. There are still differences between the subscription worker applying\na change and going through the ordinary INSERT paths, for instance with\nRLS. Also solvable.\n\n5. Andres raised in another thread the idea of switching to the table\nowner when applying changes (perhaps in a\nSECURITY_RESTRICTED_OPERATION?): \n\nhttps://www.postgresql.org/message-id/20230112033355.u5tiyr2bmuoc4jf4@awork3.anarazel.de\n\nThat seems related, and I like the idea.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Thu, 19 Jan 2023 10:32:45 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2023-01-19 at 10:45 -0500, Robert Haas wrote:\n> I wouldn't be OK with writing our own connection string parser for\n> this purpose, but using PQconninfoParse seems OK. We still have to\n> embed knowledge of which connection string parameters can trigger\n> local file access, but that doesn't seem like a massive problem to\n> me.\n\nAnother idea (I discussed with Andres some time ago) was to have an\noption to libpq to turn off file access entirely. That could be a new\nAPI function or a new connection option.\n\nThat would be pretty valuable by itself. Though we might want to\nsupport a way to pass SSL keys as values rather than file paths, so\nthat we can still do SSL.\n\nSo perhaps the answer is that it will be a small patch to get non-\nsuperuser subscription owners, but we need three or four preliminary\npatches first.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Thu, 19 Jan 2023 10:40:12 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Jan 19, 2023 at 1:40 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Thu, 2023-01-19 at 10:45 -0500, Robert Haas wrote:\n> > I wouldn't be OK with writing our own connection string parser for\n> > this purpose, but using PQconninfoParse seems OK. We still have to\n> > embed knowledge of which connection string parameters can trigger\n> > local file access, but that doesn't seem like a massive problem to\n> > me.\n>\n> Another idea (I discussed with Andres some time ago) was to have an\n> option to libpq to turn off file access entirely. That could be a new\n> API function or a new connection option.\n>\n> That would be pretty valuable by itself. Though we might want to\n> support a way to pass SSL keys as values rather than file paths, so\n> that we can still do SSL.\n\nMaybe all of that would be useful, but it doesn't seem that mandatory.\n\n> So perhaps the answer is that it will be a small patch to get non-\n> superuser subscription owners, but we need three or four preliminary\n> patches first.\n\nI guess I'm not quite seeing it. Why can't we write a small patch to\nget this working right now, probably in a few hours, and deal with any\nimprovements that people want at a later time?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 19 Jan 2023 14:11:46 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2023-01-19 at 14:11 -0500, Robert Haas wrote:\n> I guess I'm not quite seeing it. Why can't we write a small patch to\n> get this working right now, probably in a few hours, and deal with\n> any\n> improvements that people want at a later time?\n\nTo me, it's worrisome when there are more than a few loose ends, and\nhere it seems like there are more like five. No single issue is a\nblocker, but I believe we'd end up with a better user-facing solution\nif we solved a couple of these lower-level issues (and think a little\nmore about the other ones) before we expose new functionality to the\nuser.\n\nThe predefined role is probably the biggest user-facing part of the\nchange. Does it mean that members can create any number of any kind of\nsubscription? If so it may be hard to tighten down later, because we\ndon't know what existing setups might break.\n\nPerhaps we can just permit a superuser to \"ALTER SUBSCRIPTION ... OWNER\nTO <non-super>\", which makes it simpler to use while still leaving the\nresponisbility with the superuser to get it right. Maybe we even block\nthe user from altering their own subscription (would be weird but not\nmuch weirder than what we have now)? I don't know if that solves the\nproblem you're trying to solve, but it seems lower-risk.\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Thu, 19 Jan 2023 17:16:20 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-19 10:45:35 -0500, Robert Haas wrote:\n> On Wed, Jan 18, 2023 at 3:58 PM Mark Dilger\n> <mark.dilger@enterprisedb.com> wrote:\n> > > On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\n> > >\n> > > Unless I'm missing something, it seems like this could be a quite small patch.\n> >\n> > I didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\n> \n> I wouldn't be OK with writing our own connection string parser for\n> this purpose, but using PQconninfoParse seems OK. We still have to\n> embed knowledge of which connection string parameters can trigger\n> local file access, but that doesn't seem like a massive problem to me.\n\n> If we already had (or have) that logic someplace else, it would\n> probably make sense to reuse it\n\nWe hve. See at least postgres_fdw's check_conn_params(), dblink's\ndblink_connstr_check() and dblink_security_check().\n\nAs part of the fix for https://postgr.es/m/20220925232237.p6uskba2dw6fnwj2%40awork3.anarazel.de\nI am planning to introduce a bunch of server side helpers for dealing with\nlibpq (for establishing a connection while accepting interrupts). We could try\nto centralize knowledge for those checks there.\n\nThe approach of checking, after connection establishment (see\ndblink_security_check()), that we did in fact use the specified password,\nscares me somewhat. See also below.\n\n\n> The basic idea that by looking at which connection string properties are set\n> we can tell what kinds of things the connection string is going to do seems\n> sound to me.\n\nI don't think you *can* check it purely based on existing connection string\nproperties, unfortunately. Think of e.g. a pg_hba.conf line of \"local all user\npeer\" (quite reasonable config) or \"host all all 127.0.0.1/32 trust\" (less so).\n\nHence the hack with dblink_security_check().\n\n\nI think there might be a discussion somewhere about adding an option to force\nlibpq to not use certain auth methods, e.g. plaintext password/md5. It's\npossible this could be integrated.\n\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 19 Jan 2023 17:46:28 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-19 17:16:20 -0800, Jeff Davis wrote:\n> The predefined role is probably the biggest user-facing part of the\n> change. Does it mean that members can create any number of any kind of\n> subscription?\n\nI don't think we need to support complicated restriction schemes around this\nnow. I'm sure such needs exist, but I think there's more places where a simple\n\"allowed/not allowed\" suffices.\n\nYou'd presumably just grant such a permission to \"pseudo superuser\"\nusers. They can typically do a lot of bad things already, so I don't really\nsee the common need to prevent them from creating many subscriptions.\n\n\n> If so it may be hard to tighten down later, because we don't know what\n> existing setups might break.\n\nPresumably the unlimited number of subs case would still exist as an option\nlater - so I don't see the problem?\n\n\n> Perhaps we can just permit a superuser to \"ALTER SUBSCRIPTION ... OWNER\n> TO <non-super>\", which makes it simpler to use while still leaving the\n> responisbility with the superuser to get it right. Maybe we even block\n> the user from altering their own subscription (would be weird but not\n> much weirder than what we have now)? I don't know if that solves the\n> problem you're trying to solve, but it seems lower-risk.\n\nThat seems to not really get us very far. It's hard to use for users, and hard\nto make secure for the hosted PG providers.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 19 Jan 2023 17:51:22 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2023-01-19 at 17:51 -0800, Andres Freund wrote:\n> I don't think we need to support complicated restriction schemes\n> around this\n> now. I'm sure such needs exist, but I think there's more places where\n> a simple\n> \"allowed/not allowed\" suffices.\n\nIf we did follow a path like 3 (having some kind of other object\nrepresent the connection string), then it would create two different\nkinds of subscriptions that might be controlled different ways, and\nthere might be some rough edges. Might also be fine, or we might never\npursue 3.\n\nI feel like my words are being interpreted as though I don't want this\nfeature. I do, and I'm happy Robert re-raised it. I'm just trying to\nanswer his questions about why I set the work down, which is that I\nfelt some groundwork should be done before proceeding to a documented\nfeature, and I still feel that's the right thing.\n\nBut (a) that's not a very strong objection; and (b) my efforts are\nbetter spent doing some of that groundwork than arguing about the order\nin which the work should be done. So, time permitting, I may be able to\nput out a patch or two for the next 'fest.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Fri, 20 Jan 2023 00:04:12 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Jan 19, 2023 at 8:46 PM Andres Freund <andres@anarazel.de> wrote:\n> > I wouldn't be OK with writing our own connection string parser for\n> > this purpose, but using PQconninfoParse seems OK. We still have to\n> > embed knowledge of which connection string parameters can trigger\n> > local file access, but that doesn't seem like a massive problem to me.\n>\n> > If we already had (or have) that logic someplace else, it would\n> > probably make sense to reuse it\n>\n> We hve. See at least postgres_fdw's check_conn_params(), dblink's\n> dblink_connstr_check() and dblink_security_check().\n\nThat's not the same thing. It doesn't know anything about other\nparameters that might try to consult a local file, like sslcert,\nsslkey, sslrootcert, sslca, sslcrl, sslcrldir, and maybe service.\nMaybe you want to argue we don't need that, but that's what the\nearlier discussion was about.\n\n> As part of the fix for https://postgr.es/m/20220925232237.p6uskba2dw6fnwj2%40awork3.anarazel.de\n> I am planning to introduce a bunch of server side helpers for dealing with\n> libpq (for establishing a connection while accepting interrupts). We could try\n> to centralize knowledge for those checks there.\n\nMaybe. We could also add something into libpq, as Jeff proposed, e.g.\na new connection parameter\nthe_other_connection_parameters_might_try_to_trojan_the_local_host=1\nblocks all that stuff from doing anything.\n\n> The approach of checking, after connection establishment (see\n> dblink_security_check()), that we did in fact use the specified password,\n> scares me somewhat. See also below.\n\nYes, I find that extremely dubious. It blocks things that you might\nwant to do for legitimate reasons, including things that might be more\nsecure than using a password. And there's no guarantee that it\naccomplishes the intended objective either. The stated motivation for\nthat restriction was. I believe, that we don't want the outbound\nconnection to rely on the privileges available from the context in\nwhich PostgreSQL itself is running -- but for all we know the remote\nside has an IP filter that only allows the PostgreSQL host and no\nothers. Moreover, it relies on us knowing what the behavior of the\nremote server is, even though we have no way of knowing that that\nserver shares our security interests.\n\nWorse still, I have always felt that the security vulnerability that\nled to these controls being installed is pretty much fabricated: it's\nan imaginary problem. Today I went back and found the original CVE at\nhttps://nvd.nist.gov/vuln/detail/CVE-2007-3278 and it seems that at\nleast one other person agrees. The Red Hat vendor statement on that\npage says: \"Red Hat does not consider this do be a security issue.\ndblink is disabled in default configuration of PostgreSQL packages as\nshipped with Red Hat Enterprise Linux versions 2.1, 3, 4 and 5, and it\nis a configuration decision whether to grant local users arbitrary\naccess.\" I think whoever wrote that has an excellent point. I'm unable\nto discern any legitimate security purpose for this restriction. What\nI think it mostly does is (a) inconvenience users or (b) force them to\nrely on a less-secure authentication method than they would otherwise\nhave chosen.\n\n> > The basic idea that by looking at which connection string properties are set\n> > we can tell what kinds of things the connection string is going to do seems\n> > sound to me.\n>\n> I don't think you *can* check it purely based on existing connection string\n> properties, unfortunately. Think of e.g. a pg_hba.conf line of \"local all user\n> peer\" (quite reasonable config) or \"host all all 127.0.0.1/32 trust\" (less so).\n>\n> Hence the hack with dblink_security_check().\n>\n> I think there might be a discussion somewhere about adding an option to force\n> libpq to not use certain auth methods, e.g. plaintext password/md5. It's\n> possible this could be integrated.\n\nI still think you're talking about a different problem here. I'm\ntalking about the problem of knowing whether local files are going to\nbe accessed by the connection string.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 20 Jan 2023 08:25:46 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Jan 20, 2023 at 8:25 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> I still think you're talking about a different problem here. I'm\n> talking about the problem of knowing whether local files are going to\n> be accessed by the connection string.\n\nSo here's a dumb patch for this. At least in my mind, the connection\nstring sanitization/validation is the major design problem here, and\nI'm not at all sure that what I did in the attached patch is right.\nBut let's talk about that. This approach is inspired by Jeff's\ncomments about local file access upthread, but as Andres pointed out,\nthat's a completely different set of things than we worry about in\nother places. I'm not quite sure what the right model is here.\n\nThis patch incidentally allows ALTER SUBSCRIPTION .. SKIP for any\nsubscription owner, removing the existing check that limits that\noperation to superusers and replacing it with nothing. I can't really\nsee why this needs to be any more restricted than that, and\nregrettably neither the check in the existing code nor the commit that\nadded it have any comments explaining the logic behind that check. If,\nfor example, skipping a subscription could lead to a server crash,\nthat would be a reason to restrict the feature to superusers (or\nrevert it). If it's just a case of the operation being maybe not the\nright thing to do, that's not a sufficient reason to restrict it to\nsuperusers. This change is really independent of the rest of the patch\nand, if we want to do this, I will separate it into its own patch. But\nsince this is just for discussion, I didn't worry about that right\nnow.\n\nAside from the above, I don't yet see a problem here that I would\nconsider to be serious enough that we couldn't proceed. I'll try to\navoid too much repetition of what's already been said on this topic,\nbut I do want to add that I think that creating subscriptions is\nproperly viewed as a *slightly* scary operation, not a *very* scary\noperation. It lets you do two things that you couldn't otherwise. One\nis get background processes running that take up process slots and\nconsume resources -- but note that your ability to consume resources\nwith however many normal database connections you can make is\nvirtually unlimited. The other thing it lets you do is poke around the\nnetwork, maybe figure out whether some ports are open or closed, and\ntry to replicate data from any accessible servers you can find, which\ncould include ports or servers that you can't access directly. I think\nthat the superuser will be in a good position to evaluate whether that\nis a risk in a certain environment or not, and I think many superusers\nwill conclude that it isn't a big risk. I think that the main\nmotivation for NOT handing out pg_create_subscription will turn out to\nbe administrative rather than security-related i.e. they'll want to be\nsomething that falls under their authority rather than someone else's.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com","msg_date":"Fri, 20 Jan 2023 11:08:54 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-20 08:25:46 -0500, Robert Haas wrote:\n> Worse still, I have always felt that the security vulnerability that\n> led to these controls being installed is pretty much fabricated: it's\n> an imaginary problem. Today I went back and found the original CVE at\n> https://nvd.nist.gov/vuln/detail/CVE-2007-3278 and it seems that at\n> least one other person agrees. The Red Hat vendor statement on that\n> page says: \"Red Hat does not consider this do be a security issue.\n> dblink is disabled in default configuration of PostgreSQL packages as\n> shipped with Red Hat Enterprise Linux versions 2.1, 3, 4 and 5, and it\n> is a configuration decision whether to grant local users arbitrary\n> access.\" I think whoever wrote that has an excellent point. I'm unable\n> to discern any legitimate security purpose for this restriction. What\n> I think it mostly does is (a) inconvenience users or (b) force them to\n> rely on a less-secure authentication method than they would otherwise\n> have chosen.\n\nFWIW, I've certainly seen situations where having the checks prevented easy\npaths to privilege escalations. That's not to say that I like the checks, but\nI also don't think we can get away without them (or a better replacement, of\ncourse).\n\nThere are good reasons to have 'peer' authentication set up for the user\nrunning postgres, so admin scripts can connect without issues. Which\nunfortunately then also means that postgres_fdw etc can connect to the current\ndatabase as superuser, without that check. Which imo clearly is an issue.\n\nWhy do you think this is a fabricated issue?\n\n\nThe solution we have is quite bad, of course. Just because the user isn't a\nsuperuser \"immediately\" doesn't mean it doesn't have the rights to become\none somehow.\n\n\n> > > The basic idea that by looking at which connection string properties are set\n> > > we can tell what kinds of things the connection string is going to do seems\n> > > sound to me.\n> >\n> > I don't think you *can* check it purely based on existing connection string\n> > properties, unfortunately. Think of e.g. a pg_hba.conf line of \"local all user\n> > peer\" (quite reasonable config) or \"host all all 127.0.0.1/32 trust\" (less so).\n> >\n> > Hence the hack with dblink_security_check().\n> >\n> > I think there might be a discussion somewhere about adding an option to force\n> > libpq to not use certain auth methods, e.g. plaintext password/md5. It's\n> > possible this could be integrated.\n> \n> I still think you're talking about a different problem here. I'm\n> talking about the problem of knowing whether local files are going to\n> be accessed by the connection string.\n\nWhy is this only about local files, rather than e.g. also using the local\nuser?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Sat, 21 Jan 2023 14:01:34 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-20 11:08:54 -0500, Robert Haas wrote:\n> /*\n> - * Validate connection info string (just try to parse it)\n> + * Validate connection info string, and determine whether it might cause\n> + * local filesystem access to be attempted.\n> + *\n> + * If the connection string can't be parsed, this function will raise\n> + * an error and will not return. If it can, it will return true if local\n> + * filesystem access may be attempted and false otherwise.\n> */\n> -static void\n> +static bool\n> libpqrcv_check_conninfo(const char *conninfo)\n> {\n> \tPQconninfoOption *opts = NULL;\n> +\tPQconninfoOption *opt;\n> \tchar\t *err = NULL;\n> +\tbool\t\tresult = false;\n> \n> \topts = PQconninfoParse(conninfo, &err);\n> \tif (opts == NULL)\n> @@ -267,7 +274,40 @@ libpqrcv_check_conninfo(const char *conninfo)\n> \t\t\t\t errmsg(\"invalid connection string syntax: %s\", errcopy)));\n> \t}\n> \n> +\tfor (opt = opts; opt->keyword != NULL; ++opt)\n> +\t{\n> +\t\t/* Ignore connection options that are not present. */\n> +\t\tif (opt->val == NULL)\n> +\t\t\tcontinue;\n> +\n> +\t\t/* For all these parameters, the value is a local filename. */\n> +\t\tif (strcmp(opt->keyword, \"passfile\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"sslcert\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"sslkey\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"sslrootcert\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"sslcrl\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"sslcrldir\") == 0 ||\n> +\t\t\tstrcmp(opt->keyword, \"service\") == 0)\n> +\t\t{\n> +\t\t\tresult = true;\n> +\t\t\tbreak;\n> +\t\t}\n\nDo we need to think about 'options' allowing anything bad? I don't\nimmediately* see a problem, but ...\n\n\n> +\n> +\t\t/*\n> +\t\t * For the host parameter, the value might be a local filename.\n> +\t\t * It might also be a reference to the local host's abstract UNIX\n> +\t\t * socket namespace, which we consider equivalent to a local pathname\n> +\t\t * for security purporses.\n> +\t\t */\n> +\t\tif (strcmp(opt->keyword, \"host\") == 0 && is_unixsock_path(opt->val))\n> +\t\t{\n> +\t\t\tresult = true;\n> +\t\t\tbreak;\n> +\t\t}\n> +\t}\n\nHm, what about kerberos / gss / SSPI? Aren't those essentially also tied to\nthe local filesystem / user?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Sat, 21 Jan 2023 14:10:57 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, 2023-01-21 at 14:01 -0800, Andres Freund wrote:\n> There are good reasons to have 'peer' authentication set up for the\n> user\n> running postgres, so admin scripts can connect without issues. Which\n> unfortunately then also means that postgres_fdw etc can connect to\n> the current\n> database as superuser, without that check. Which imo clearly is an\n> issue.\n\nPerhaps we should have a way to directly turn on/off authentication\nmethods in libpq through API functions and/or options?\n\nThis reminds me of the \"channel_binding=required\" option. We considered\nsome similar alternatives for that feature.\n\n> Why is this only about local files, rather than e.g. also using the\n> local\n> user?\n\nIt's not, but we happen to already have pg_read_server_files, and it\nmakes sense to use that at least for files referenced directly in the\nconnection string. You're right that it's incomplete, and also that it\ndoesn't make a lot of sense for files accessed indirectly.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Sun, 22 Jan 2023 09:05:27 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-22 09:05:27 -0800, Jeff Davis wrote:\n> On Sat, 2023-01-21 at 14:01 -0800, Andres Freund wrote:\n> > There are good reasons to have 'peer' authentication set up for the\n> > user\n> > running postgres, so admin scripts can connect without issues. Which\n> > unfortunately then also means that postgres_fdw etc can connect to\n> > the current\n> > database as superuser, without that check. Which imo clearly is an\n> > issue.\n> \n> Perhaps we should have a way to directly turn on/off authentication\n> methods in libpq through API functions and/or options?\n\nYes. There's an in-progress patch adding, I think, pretty much what is\nrequired here:\nhttps://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\n\nrequire_auth=a,b,c\n\nI think an allowlist approach is the right thing for the subscription (and\npostgres_fdw/dblink) use case, otherwise we'll add some auth method down the\nline without updating what's disallowed in the subscription code.\n\n\n> > Why is this only about local files, rather than e.g. also using the local\n> > user?\n> \n> It's not, but we happen to already have pg_read_server_files, and it\n> makes sense to use that at least for files referenced directly in the\n> connection string. You're right that it's incomplete, and also that it\n> doesn't make a lot of sense for files accessed indirectly.\n\nI just meant that we need to pay attention to user-based permissions as well.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Sun, 22 Jan 2023 17:52:55 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Jan 21, 2023 at 5:01 PM Andres Freund <andres@anarazel.de> wrote:\n> There are good reasons to have 'peer' authentication set up for the user\n> running postgres, so admin scripts can connect without issues. Which\n> unfortunately then also means that postgres_fdw etc can connect to the current\n> database as superuser, without that check. Which imo clearly is an issue.\n>\n> Why do you think this is a fabricated issue?\n\nWell, if I have a bunch of PostgreSQL machines on the network that all\nallow each other to log in without requiring anything much in the way\nof passwords or closely-guarded SSL certificates or anything, and then\nI grant to the users on those machines the right to make connections\nto the other machines using arbitrary connection strings, whose fault\nis it when security is compromised? We seem to be taking the policy\nthat it's PostgreSQL's fault if it doesn't block something bad from\nhappening there, but it seems to me that if you gate incoming\nPostgreSQL connections only by source IP address and then also give\nunprivileged users the ability to choose their source IP address, you\nshould expect to have a problem.\n\nI will admit that this is not an open-and-shut case, because a\npasswordless login back to the bootstrap superuser account from the\nlocal machine is a pretty common scenario and doesn't feel\nintrinsically unreasonable to me, and I hadn't thought about that as a\npotential attack vector.\n\nHowever, I still think there's a problem with putting all the\nresponsibility on PostgreSQL. The problem, specifically, is that we're\nspeculating wildly as to the user's intent. If we say, as we currently\ndo, that we're only going to allow connections if they require a\npassword, then we're making a judgement that the superuser couldn't\nhave intended to allow the postgres_fdw to make a passwordless\nconnection. On the other hand, if we say, as we also currently do,\nthat the postgres_fdw user is free to set the sslcert parameter to\nanything they like, then we're making a judgement that the superuser\nis totally OK with that being set to any file on the local filesystem.\nNeither of those conclusions seems sound to me. The superuser may, or\nmay not, have intended to allow passwordless logins, and they may, or\nmay not, have intended for any SSL certificates stored locally to be\nusable by outbound connection attempts.\n\nAnd that's what I really dislike about the you-must-use-a-password\nrule that we have right now. It embeds a policy decision about what\nusers do or do not want to allow. We've uncritically copied that\npolicy decision around to more and more places, and we've added\nworkarounds in some places for the fact that, well, you know, it might\nnot actually be what everybody wants (6136e94d), but it doesn't seem\nlike we've ever really acknowledged that we *made* a policy decision.\nAnd that means we haven't really had a debate about the merits of this\n*particular* rule, which seems to me to be highly debatable. It looks\nto me like there's both stuff you might not want to allow that this\nrule does not block, and also stuff you might want to allow that this\nrule does block, and also that different people can want different\nthings yet this rule applies uniformly to everyone.\n\n> > I still think you're talking about a different problem here. I'm\n> > talking about the problem of knowing whether local files are going to\n> > be accessed by the connection string.\n>\n> Why is this only about local files, rather than e.g. also using the local\n> user?\n\nBecause there's nothing you can do about the local-user case.\n\nIf I'm asked to attempt to connect to a PostgreSQL server, and I\nchoose to do that, and the connection succeeds, all I know is that the\nconnection actually succeeded. I do not know why the remote machine\nchose to accept the connection. If I supplied a password or an SSL\ncertificate or some such thing, then it seems likely that the remote\nmachine accepted that connection because I supplied that particular\npassword or SSL certificate, but it could also be because the remote\nmachine accepts all connections from Robert, or all connections\nwhatsoever, or all connections on Mondays. I just don't know. If I'm\nworried that the person is asking me to make the connection is trying\nto trick me into doing something that they can't do themselves, I\ncould refuse to read a password from a local password store or an SSL\ncertificate from a local certificate file or otherwise refuse to do\nanything special to try to get their connection request accepted, and\nthen if it does get accepted anyway, I know that they weren't relying\non any of those resources that I refused to use. But, if I attempt a\nplain vanilla, totally password-less connection and it works, I have\nno way of knowing whether that happened because I'm Robert or for some\nother reason.\n\nTo put that another way, if I'm making a connection on behalf of an\nuntrusted party, I can choose not to supply an SSL certificate, or not\nto supply a password. But I cannot choose to not be myself.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 11:34:32 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sun, Jan 22, 2023 at 8:52 PM Andres Freund <andres@anarazel.de> wrote:\n> > Perhaps we should have a way to directly turn on/off authentication\n> > methods in libpq through API functions and/or options?\n>\n> Yes. There's an in-progress patch adding, I think, pretty much what is\n> required here:\n> https://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\n>\n> require_auth=a,b,c\n>\n> I think an allowlist approach is the right thing for the subscription (and\n> postgres_fdw/dblink) use case, otherwise we'll add some auth method down the\n> line without updating what's disallowed in the subscription code.\n\nSo what would we do here, exactly? We could force a require_auth\nparameter into the provided connection string, although I'm not quite\nsure of the details there, but what value should we force? Is that\ngoing to be something hard-coded, or something configurable? If\nconfigurable, where does that configuration get stored?\n\nRegardless, this only allows connection strings to be restricted along\none axis: authentication type. If you want to let people connect only\nto a certain subnet or whatever, you're still out of luck.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 12:39:50 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Jan 21, 2023 at 5:11 PM Andres Freund <andres@anarazel.de> wrote:\n> > + /* For all these parameters, the value is a local filename. */\n> > + if (strcmp(opt->keyword, \"passfile\") == 0 ||\n> > + strcmp(opt->keyword, \"sslcert\") == 0 ||\n> > + strcmp(opt->keyword, \"sslkey\") == 0 ||\n> > + strcmp(opt->keyword, \"sslrootcert\") == 0 ||\n> > + strcmp(opt->keyword, \"sslcrl\") == 0 ||\n> > + strcmp(opt->keyword, \"sslcrldir\") == 0 ||\n> > + strcmp(opt->keyword, \"service\") == 0)\n> > + {\n> > + result = true;\n> > + break;\n> > + }\n>\n> Do we need to think about 'options' allowing anything bad? I don't\n> immediately* see a problem, but ...\n\nIf it is, it'd be a different kind of bad. What these parameters all\nhave in common is that they allow you to read some local file and\nmaybe benefit from that during the authentication process. options\ndoesn't let you to do anything like that, and by definition kind of\ncan't, because it's just a string to be sent to the remote server. As\nI noted in my other responses, the local superuser could want to\nimpose any arbitrary restriction the connection strings users can\nchoose, and so it's just as plausible that they want to restrict\noptions as anything else; but this test is about something more\nspecific.\n\n> > + /*\n> > + * For the host parameter, the value might be a local filename.\n> > + * It might also be a reference to the local host's abstract UNIX\n> > + * socket namespace, which we consider equivalent to a local pathname\n> > + * for security purporses.\n> > + */\n> > + if (strcmp(opt->keyword, \"host\") == 0 && is_unixsock_path(opt->val))\n> > + {\n> > + result = true;\n> > + break;\n> > + }\n> > + }\n>\n> Hm, what about kerberos / gss / SSPI? Aren't those essentially also tied to\n> the local filesystem / user?\n\nUh, I don't know. It doesn't seem so directly true as in these cases,\nbut what's your thought?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 13:21:31 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-23 11:34:32 -0500, Robert Haas wrote:\n> I will admit that this is not an open-and-shut case, because a\n> passwordless login back to the bootstrap superuser account from the\n> local machine is a pretty common scenario and doesn't feel\n> intrinsically unreasonable to me, and I hadn't thought about that as a\n> potential attack vector.\n\nI think it's 90% of the problem... There's IMO no particularly good\nalternative to a passwordless login for the bootstrap superuser, and it's the\naccount you least want to expose...\n\n\n> > > I still think you're talking about a different problem here. I'm\n> > > talking about the problem of knowing whether local files are going to\n> > > be accessed by the connection string.\n> >\n> > Why is this only about local files, rather than e.g. also using the local\n> > user?\n> \n> Because there's nothing you can do about the local-user case.\n> \n> If I'm asked to attempt to connect to a PostgreSQL server, and I\n> choose to do that, and the connection succeeds, all I know is that the\n> connection actually succeeded.\n\nWell, there is PQconnectionUsedPassword()... Not that it's a great answer.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 23 Jan 2023 10:26:39 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> I will admit that this is not an open-and-shut case, because a\n> passwordless login back to the bootstrap superuser account from the\n> local machine is a pretty common scenario and doesn't feel\n> intrinsically unreasonable to me, and I hadn't thought about that as a\n> potential attack vector.\n\nIt seems to me like that's _the_ primary attack vector. I think I\nagree with you that the password requirement is an overly large\nhammer, but I don't think it's right (or safe/helpful to DBAs reading\nalong) to describe it as a manufactured concern.\n\n> If I'm asked to attempt to connect to a PostgreSQL server, and I\n> choose to do that, and the connection succeeds, all I know is that the\n> connection actually succeeded. I do not know why the remote machine\n> chose to accept the connection. If I supplied a password or an SSL\n> certificate or some such thing, then it seems likely that the remote\n> machine accepted that connection because I supplied that particular\n> password or SSL certificate, but it could also be because the remote\n> machine accepts all connections from Robert, or all connections\n> whatsoever, or all connections on Mondays. I just don't know.\n\nAs of SYSTEM_USER, I think this is no longer the case -- after\nconnection establishment, you can ask the server who was authenticated\nand why. (It doesn't explain why you were authorized to be that\nparticular user, but that seems maybe less important wen you're trying\nto disallow ambient authentication.)\n\nIf my require_auth patchset gets in, you'd be able to improve on this\nby rejecting all ambient forms of authentication at the protocol level\n(require_auth=password,md5,scram-sha-256). You could even go a step\nfurther and disable ambient transport authentication\n(sslcertmode=disable gssencmode=disable), which keeps a proxied\nconnection from making use of a client cert or a Kerberos cache. But\nfor postgres_fdw, at least, that carries a risk of disabling current\nuse cases. Stephen and I had a discussion about one such case in the\nKerberos delegation thread [1].\n\nIt doesn't help you if you want to differentiate one form of ambient\nauth (trust/peer/etc.) from another, since they look the same to the\nprotocol. But for e.g. postgres_fdw I'm not sure why you would want to\ndifferentiate between those cases, because they all seem bad.\n\n> To put that another way, if I'm making a connection on behalf of an\n> untrusted party, I can choose not to supply an SSL certificate, or not\n> to supply a password. But I cannot choose to not be myself.\n\n(IMO, you're driving towards a separation of the proxy identity from\nthe user identity. Other protocols do that too.)\n\n--Jacob\n\n[1] https://www.postgresql.org/message-id/flat/23337c51-7a48-d5a8-569d-ef3ce6fe235f%40timescale.com#38b4033256d9d95773963ce938cbe3ea\n\n\n","msg_date":"Mon, 23 Jan 2023 10:27:27 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-23 12:39:50 -0500, Robert Haas wrote:\n> On Sun, Jan 22, 2023 at 8:52 PM Andres Freund <andres@anarazel.de> wrote:\n> > > Perhaps we should have a way to directly turn on/off authentication\n> > > methods in libpq through API functions and/or options?\n> >\n> > Yes. There's an in-progress patch adding, I think, pretty much what is\n> > required here:\n> > https://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\n> >\n> > require_auth=a,b,c\n> >\n> > I think an allowlist approach is the right thing for the subscription (and\n> > postgres_fdw/dblink) use case, otherwise we'll add some auth method down the\n> > line without updating what's disallowed in the subscription code.\n> \n> So what would we do here, exactly? We could force a require_auth\n> parameter into the provided connection string, although I'm not quite\n> sure of the details there\n\nIf we parse the connection string first, we can ensure that our values take\nprecedence, that shouldn't be an issue, I think.\n\n\n> , but what value should we force? Is that going to be something hard-coded,\n> or something configurable? If configurable, where does that configuration\n> get stored?\n\nI would probably start with something hardcoded, perhaps with an adjusted\nvalue depending on things like pg_read_server_files.\n\nI'd say just allowing password (whichever submethod), ssl is a good start,\nwith something like your existing code to prevent file access for ssl unless\npg_read_server_files is granted.\n\n\nI don't think kerberos, gss, peer, sspi would be safe.\n\n\n> Regardless, this only allows connection strings to be restricted along\n> one axis: authentication type. If you want to let people connect only\n> to a certain subnet or whatever, you're still out of luck.\n\nTrue. But I think it'd get us a large percentage of the use cases.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 23 Jan 2023 10:35:33 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 23, 2023 at 1:26 PM Andres Freund <andres@anarazel.de> wrote:\n> > If I'm asked to attempt to connect to a PostgreSQL server, and I\n> > choose to do that, and the connection succeeds, all I know is that the\n> > connection actually succeeded.\n>\n> Well, there is PQconnectionUsedPassword()... Not that it's a great answer.\n\nSure, but that's making an inference about why the remote side did\nwhat it did. It's not fantastic to have a security model that relies\non connecting to a server chosen by the user and having it tell us\ntruthfully whether or not it relied on the password. Granted, it won't\nlie unless it's been hacked, and we're trying to protect it, not\nourselves, so the only thing that happens if it does lie is that it\ngets hacked a second time, so I guess there's no real vulnerability?\nBut I feel like we'd be on far sounder footing if we our security\npolicy were based on deciding what we are willing to do (are we\nwilling to read that file? are we willing to attempt that\nauthentication method?) and before we actually do it, rather than on\ntrying to decide after-the-fact whether what we did is OK based on\nwhat the remote side tells us about how things turned out.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 13:39:43 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-23 10:27:27 -0800, Jacob Champion wrote:\n> On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> > I will admit that this is not an open-and-shut case, because a\n> > passwordless login back to the bootstrap superuser account from the\n> > local machine is a pretty common scenario and doesn't feel\n> > intrinsically unreasonable to me, and I hadn't thought about that as a\n> > potential attack vector.\n> \n> It seems to me like that's _the_ primary attack vector. I think I\n> agree with you that the password requirement is an overly large\n> hammer, but I don't think it's right (or safe/helpful to DBAs reading\n> along) to describe it as a manufactured concern.\n\n+1\n\n\n> > If I'm asked to attempt to connect to a PostgreSQL server, and I\n> > choose to do that, and the connection succeeds, all I know is that the\n> > connection actually succeeded. I do not know why the remote machine\n> > chose to accept the connection. If I supplied a password or an SSL\n> > certificate or some such thing, then it seems likely that the remote\n> > machine accepted that connection because I supplied that particular\n> > password or SSL certificate, but it could also be because the remote\n> > machine accepts all connections from Robert, or all connections\n> > whatsoever, or all connections on Mondays. I just don't know.\n> \n> As of SYSTEM_USER, I think this is no longer the case -- after\n> connection establishment, you can ask the server who was authenticated\n> and why. (It doesn't explain why you were authorized to be that\n> particular user, but that seems maybe less important wen you're trying\n> to disallow ambient authentication.)\n\nThere's not enough documentation for SYSTEM_USER imo.\n\n\n\n> You could even go a step further and disable ambient transport\n> authentication (sslcertmode=disable gssencmode=disable), which keeps a\n> proxied connection from making use of a client cert or a Kerberos cache. But\n> for postgres_fdw, at least, that carries a risk of disabling current use\n> cases. Stephen and I had a discussion about one such case in the Kerberos\n> delegation thread [1].\n\nI did not find that very convincing for today's code. The likelihood of\nsomething useful being prevented seems far far lower than preventing privilege\nleakage...\n\n\n> It doesn't help you if you want to differentiate one form of ambient\n> auth (trust/peer/etc.) from another, since they look the same to the\n> protocol. But for e.g. postgres_fdw I'm not sure why you would want to\n> differentiate between those cases, because they all seem bad.\n\nIt might be possible to teach libpq to differentiate peer from trust (by\ndisabling passing the current user), or we could tell the server via an option\nto disable peer. But as you say, I don't think it'd buy us much.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 23 Jan 2023 11:05:33 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 23, 2023 at 1:27 PM Jacob Champion <jchampion@timescale.com> wrote:\n> On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> > I will admit that this is not an open-and-shut case, because a\n> > passwordless login back to the bootstrap superuser account from the\n> > local machine is a pretty common scenario and doesn't feel\n> > intrinsically unreasonable to me, and I hadn't thought about that as a\n> > potential attack vector.\n>\n> It seems to me like that's _the_ primary attack vector. I think I\n> agree with you that the password requirement is an overly large\n> hammer, but I don't think it's right (or safe/helpful to DBAs reading\n> along) to describe it as a manufactured concern.\n\nFirst, sorry about the wording. I try to get it right, but sometimes I don't.\n\nSecond, the reason why I described it as a manufactured issue is\nbecause it's a bit like asking someone to stand under a ladder and\nthen complaining when they get hit in the head by a falling object.\nIt's not that I think it's good for people to get a free exploit to\nsuperuser, or to get hit in the head by falling objects. It's just\nthat you can't have the things that together lead to some outcome\nwithout also getting the outcome. It seems to me that we basically let\nthe malicious connection to the target host succeed, and then say ...\noh, never mind, we may have made this connection under false\npretenses, so we shan't use it after all. What I was attempting to\nargue is that we shouldn't let things get that far. Either the victim\nshould be able to protect itself from the malicious connection, or the\nconnection attempt shouldn't be allowed in the first place, or both.\nBlocking the connection attempt after the fact feels like too little,\ntoo late.\n\nFor instance, what if the connection string itself caused SQL to be\nexecuted on the remote side, as in the case of target_session_attrs?\nOr what if we got those logon triggers that people have been wanting\nfor years? Or what if the remote server speaks the PostgreSQL protocol\nbut isn't really PostgreSQL and does ... whatever ... when you just\nconnect to it?\n\n> As of SYSTEM_USER, I think this is no longer the case -- after\n> connection establishment, you can ask the server who was authenticated\n> and why. (It doesn't explain why you were authorized to be that\n> particular user, but that seems maybe less important wen you're trying\n> to disallow ambient authentication.)\n\nI think this is too after-the-fact, as discussed above.\n\n> If my require_auth patchset gets in, you'd be able to improve on this\n> by rejecting all ambient forms of authentication at the protocol level\n> (require_auth=password,md5,scram-sha-256). You could even go a step\n> further and disable ambient transport authentication\n> (sslcertmode=disable gssencmode=disable), which keeps a proxied\n> connection from making use of a client cert or a Kerberos cache. But\n> for postgres_fdw, at least, that carries a risk of disabling current\n> use cases. Stephen and I had a discussion about one such case in the\n> Kerberos delegation thread [1].\n\nYes, this is why I think that the system administrator needs to have\nsome control over policy, instead of just having a hard-coded rule\nthat applies to everyone.\n\nI'm not completely sure that this is good enough in terms of blocking\nthe attack as early as I think we should. This is all happening in the\nmidst of a connection attempt. If the remote server says, \"hey, what's\nyour password?\" and we refuse to answer that question, well that seems\nsomewhat OK. But what if we're hoping to be asked for a password and\nthe remote server doesn't ask? Then we don't find out that things\naren't right until after we've already logged in, and that gets back\nto what I talk about above.\n\n> > To put that another way, if I'm making a connection on behalf of an\n> > untrusted party, I can choose not to supply an SSL certificate, or not\n> > to supply a password. But I cannot choose to not be myself.\n>\n> (IMO, you're driving towards a separation of the proxy identity from\n> the user identity. Other protocols do that too.)\n\nHmm, interesting.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 14:47:06 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 23, 2023 at 2:47 PM Robert Haas <robertmhaas@gmail.com> wrote:\n> Second, the reason why I described it as a manufactured issue is\n> because it's a bit like asking someone to stand under a ladder and\n> then complaining when they get hit in the head by a falling object.\n> It's not that I think it's good for people to get a free exploit to\n> superuser, or to get hit in the head by falling objects. It's just\n> that you can't have the things that together lead to some outcome\n> without also getting the outcome.\n\nI left out a sentence here. What I meant to say was we can't both\nallow passwordless loopback connections to the bootstrap superuser and\nalso allow postgres_fdw to connect to anything that the user requests\nand then be surprised when that user can get into the superuser\naccount. The natural outcome of combining those two things is that\nsuperuser gets hacked.\n\nThe password requirement just *barely* prevents that attack from\nworking, almost, maybe, while at the same time managing to block\nthings that people want to do for totally legitimate reasons. But\nIMHO, the real problem is that combining those two things is extremely\ndangerous.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 23 Jan 2023 14:52:25 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, 2023-01-20 at 11:08 -0500, Robert Haas wrote:\n> On Fri, Jan 20, 2023 at 8:25 AM Robert Haas <robertmhaas@gmail.com>\n> wrote:\n> > I still think you're talking about a different problem here. I'm\n> > talking about the problem of knowing whether local files are going\n> > to\n> > be accessed by the connection string.\n> \n> So here's a dumb patch for this. At least in my mind, the connection\n> string sanitization/validation is the major design problem here\n\nI believe your patch conflates two use cases:\n\n(A) Tightly-coupled servers that are managed by the administrator. In\nthis case, there are a finite number of connection strings to make, and\nthe admin knows about all of them. Validation is a poor solution for\nthis use case, because we get into the weeds trying to figure out\nwhat's safe or not, overriding the admin's better judgement in some\ncases and letting through connection strings that might be unsafe. A\nmuch better solution is to simply declare the connection strings as\nsome kind of object (perhaps a SERVER object), and hand out privileges\nor inherit them from a predefined role. Having connection string\nobjects is also just a better UI: it allows changes to connection\nstrings over time to adapt to changing security needs, and allows a\nsimple name that is much easier to type and read.\n\n(B) Loosely-coupled servers that the admin doesn't know about, but\nwhich might be perfectly safe to access. Validation is useful here, but\nit's a long road of fine-grained privileges around acceptable hosts,\nIPs, authentication types, file access, password sources, password\nprotocols, connection options, etc. The right solution here is to\nidentify the sub-usecases of loosely-coupled servers, and enable them\n(with the appropriate controls) one at a time. Arguably, that's already\nwhat's happened by demanding a password (even if we don't like the\nmechanism, it does seem to work for some important cases).\n\nIs your patch targeted at use case (A), (B), or both?\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Mon, 23 Jan 2023 12:50:04 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 1/23/23 11:05, Andres Freund wrote:\n> There's not enough documentation for SYSTEM_USER imo.\n\nIf we were to make use of SYSTEM_USER programmatically (and based on\nwhat Robert wrote downthread, that's probably not what's desired), I\nthink we'd have to make more guarantees about how it can be parsed and\nthe values that you can expect. Right now it's meant mostly for human\nconsumption.\n\n>> You could even go a step further and disable ambient transport\n>> authentication (sslcertmode=disable gssencmode=disable), which keeps a\n>> proxied connection from making use of a client cert or a Kerberos cache. But\n>> for postgres_fdw, at least, that carries a risk of disabling current use\n>> cases. Stephen and I had a discussion about one such case in the Kerberos\n>> delegation thread [1].\n> \n> I did not find that very convincing for today's code. The likelihood of\n> something useful being prevented seems far far lower than preventing privilege\n> leakage...\n\nFair enough. Preventing those credentials from being pulled in by\ndefault would effectively neutralize my concern for the delegation\npatchset, too.\n\n--Jacob\n\n\n\n","msg_date":"Mon, 23 Jan 2023 16:23:52 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 1/23/23 11:52, Robert Haas wrote:\n> On Mon, Jan 23, 2023 at 2:47 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>> Second, the reason why I described it as a manufactured issue is\n>> because it's a bit like asking someone to stand under a ladder and\n>> then complaining when they get hit in the head by a falling object.\n>> It's not that I think it's good for people to get a free exploit to\n>> superuser, or to get hit in the head by falling objects. It's just\n>> that you can't have the things that together lead to some outcome\n>> without also getting the outcome.\n>\n> I left out a sentence here. What I meant to say was we can't both\n> allow passwordless loopback connections to the bootstrap superuser and\n> also allow postgres_fdw to connect to anything that the user requests\n> and then be surprised when that user can get into the superuser\n> account. The natural outcome of combining those two things is that\n> superuser gets hacked.\n>\n> The password requirement just *barely* prevents that attack from\n> working, almost, maybe, while at the same time managing to block\n> things that people want to do for totally legitimate reasons. But\n> IMHO, the real problem is that combining those two things is extremely\n> dangerous.\n\nI don't disagree. I'm worried that the unspoken conclusion being\npresented is \"it's such an obvious problem that we should just leave it\nto the DBAs,\" which I very much disagree with, but I may be reading too\nmuch into it.\n\n> It seems to me that we basically let\n> the malicious connection to the target host succeed, and then say ...\n> oh, never mind, we may have made this connection under false\n> pretenses, so we shan't use it after all. What I was attempting to\n> argue is that we shouldn't let things get that far. Either the victim\n> should be able to protect itself from the malicious connection, or the\n> connection attempt shouldn't be allowed in the first place, or both.\n> Blocking the connection attempt after the fact feels like too little,\n> too late.\n\nExpanding on my previous comment, you could give the client a way to say\n\"I am a proxy, and I'm connecting on behalf of this user, and here are\nboth my credentials and their credentials. So if you were planning to,\nsay, authorize me as superuser based on my IP address... maybe don't do\nthat?\"\n\n(You can sort of implement this today, by giving the proxy a client\ncertificate for transport authn, having it provide the in-band authn for\nthe user, and requiring both at the server. It's not very flexible.)\n\nI think this has potential overlap with Magnus' PROXY proposal [1], and\nalso the case where we want pgbouncer to authenticate itself and then\nperform actions on behalf of someone else [2], and maybe SASL's authzid\nconcept. I don't think one solution will hit all of the desired use\ncases, but there are directions that can be investigated.\n\n> I'm not completely sure that this is good enough in terms of blocking\n> the attack as early as I think we should. This is all happening in the\n> midst of a connection attempt. If the remote server says, \"hey, what's\n> your password?\" and we refuse to answer that question, well that seems\n> somewhat OK. But what if we're hoping to be asked for a password and\n> the remote server doesn't ask?\n\nrequire_auth should still successfully mitigate the target_session_attrs\ncase (going back to the examples you provided). It looks like the SQL is\ninitiated from the client side, so require_auth will notice that there\nwas no authentication performed and bail out before we get there.\n\nFor the hypothetical logon trigger, or any case where the server does\nsomething on behalf of a user upon connection, I agree it doesn't help you.\n\n--Jacob\n\n[1]\nhttps://www.postgresql.org/message-id/flat/CABUevExJ0ifpUEiX4uOREy0s2kHBrBrb=pXLEHhpMTR1vVR1XA@mail.gmail.com\n[2]\nhttps://www.postgresql.org/message-id/CAMT0RQR2fxeaPLHXappBCGEjHJiPCBJMPOHoDWiaYLjuieR0sg%40mail.gmail.com\n\n\n","msg_date":"Mon, 23 Jan 2023 16:24:34 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 23, 2023 at 7:24 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > The password requirement just *barely* prevents that attack from\n> > working, almost, maybe, while at the same time managing to block\n> > things that people want to do for totally legitimate reasons. But\n> > IMHO, the real problem is that combining those two things is extremely\n> > dangerous.\n>\n> I don't disagree. I'm worried that the unspoken conclusion being\n> presented is \"it's such an obvious problem that we should just leave it\n> to the DBAs,\" which I very much disagree with, but I may be reading too\n> much into it.\n\nTo be honest, that was my first instinct here, but I see the problems\nbetter now than I did at the beginning of this discussion.\n\n> Expanding on my previous comment, you could give the client a way to say\n> \"I am a proxy, and I'm connecting on behalf of this user, and here are\n> both my credentials and their credentials. So if you were planning to,\n> say, authorize me as superuser based on my IP address... maybe don't do\n> that?\"\n>\n> (You can sort of implement this today, by giving the proxy a client\n> certificate for transport authn, having it provide the in-band authn for\n> the user, and requiring both at the server. It's not very flexible.)\n>\n> I think this has potential overlap with Magnus' PROXY proposal [1], and\n> also the case where we want pgbouncer to authenticate itself and then\n> perform actions on behalf of someone else [2], and maybe SASL's authzid\n> concept. I don't think one solution will hit all of the desired use\n> cases, but there are directions that can be investigated.\n\nI think this has some potential, but it's pretty complex, seeming to\nrequire protocol extensions and having backward-compatibility problems\nand so on. What do you think about something in the spirit of a\nreverse-pg_hba.conf? The idea being that PostgreSQL facilities that\nmake outbound connections are supposed to ask it whether those\nconnections are OK to initiate. Then you could have a default\nconfiguration that basically says \"don't allow loopback connections\"\nor \"require passwords all the time\" or whatever we like, and the DBA\ncan change that as desired. We could teach dblink, postgres_fdw, and\nCREATE SUBSCRIPTION to use this new thing, and third-party code could\nadopt it if it likes.\n\nEven if we do that, some kind of proxy protocol support might be very\ndesirable. I'm not against that. But I think that DBAs need better\ncontrol over what kind of outbound connections they want to permit,\ntoo.\n\n> For the hypothetical logon trigger, or any case where the server does\n> something on behalf of a user upon connection, I agree it doesn't help you.\n\nI don't think the logon trigger thing is all *that* hypothetical. We\ndon't have it yet, but there have been patches proposed repeatedly for\nmany years.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 24 Jan 2023 08:50:42 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\nOn 2023-01-24 Tu 08:50, Robert Haas wrote:\n>\n> What do you think about something in the spirit of a\n> reverse-pg_hba.conf? The idea being that PostgreSQL facilities that\n> make outbound connections are supposed to ask it whether those\n> connections are OK to initiate. Then you could have a default\n> configuration that basically says \"don't allow loopback connections\"\n> or \"require passwords all the time\" or whatever we like, and the DBA\n> can change that as desired. We could teach dblink, postgres_fdw, and\n> CREATE SUBSCRIPTION to use this new thing, and third-party code could\n> adopt it if it likes.\n>\n\nI kinda like this idea, especially if we could specify the context that\nrules are to apply in. e.g. postgres_fdw, mysql_fdw etc. I'd certainly\ngive it an outing in the redis_fdw if appropriate.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 24 Jan 2023 12:24:05 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Jan 24, 2023 at 5:50 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> I think this has some potential, but it's pretty complex, seeming to\n> require protocol extensions and having backward-compatibility problems\n> and so on.\n\nYeah.\n\n> What do you think about something in the spirit of a\n> reverse-pg_hba.conf? The idea being that PostgreSQL facilities that\n> make outbound connections are supposed to ask it whether those\n> connections are OK to initiate. Then you could have a default\n> configuration that basically says \"don't allow loopback connections\"\n> or \"require passwords all the time\" or whatever we like, and the DBA\n> can change that as desired.\n\nWell, I'll have to kick the idea around a little bit. Kneejerk reactions:\n\n- It's completely reasonable to let a proxy operator restrict how that\nproxy is used. I doubt very much that a typical DBA wants to be\noperating an open proxy.\n\n- I think the devil will be in the details of the configuration\ndesign. Lists of allowed destination authorities (in the URI sense),\noptions that must be present/absent/overridden, those sound great. But\nyour initial examples of allow-loopback and require-passwords options\nare in the \"make the DBA deal with it\" line of thinking, IMO. I think\nit's difficult for someone to reason through those correctly the first\ntime, even for experts. I'd like to instead see the core problem --\nthat *any* ambient authentication used by a proxy is inherently risky\n-- exposed as a highly visible concept in the config, so that it's\nhard to make mistakes.\n\n- I'm inherently skeptical of solutions that require all clients --\nproxies, in this case -- to be configured correctly in order for a\nserver to be able to protect itself. (But I also have a larger\nappetite for security options that break compatibility when turned on.\n:D)\n\n> > For the hypothetical logon trigger, or any case where the server does\n> > something on behalf of a user upon connection, I agree it doesn't help you.\n>\n> I don't think the logon trigger thing is all *that* hypothetical. We\n> don't have it yet, but there have been patches proposed repeatedly for\n> many years.\n\nOkay. I think this thread has applicable lessons -- if connection\nestablishment itself leads to side effects, all actors in the\necosystem (bouncers, proxies) have to be hardened against making those\nconnections passively. I know we're very different from HTTP, but it\nfeels similar to their concept of method safety and the consequences\nof violating it.\n\n--Jacob\n\n\n","msg_date":"Tue, 24 Jan 2023 11:18:44 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"[ Changing subject line to something more appropriate: This is\nbranched from the \"Non-superuser subscription owners\" thread, but the\ntopic has become connection security more generally for outbound\nconnections from a PostgreSQL instance, the inadequacies of just\ntrying to require that such connections always use a password, and\nrelated problems. I proposed some kind of \"reverse pg_hba.conf file\"\nas a way of allowing configurable limits on such outbound connections.\n]\n\nOn Tue, Jan 24, 2023 at 2:18 PM Jacob Champion <jchampion@timescale.com> wrote:\n> - It's completely reasonable to let a proxy operator restrict how that\n> proxy is used. I doubt very much that a typical DBA wants to be\n> operating an open proxy.\n\nThat's very well put. It's precisely what I was thinking, but\nexpressed much more clearly.\n\n> - I think the devil will be in the details of the configuration\n> design. Lists of allowed destination authorities (in the URI sense),\n> options that must be present/absent/overridden, those sound great. But\n> your initial examples of allow-loopback and require-passwords options\n> are in the \"make the DBA deal with it\" line of thinking, IMO. I think\n> it's difficult for someone to reason through those correctly the first\n> time, even for experts. I'd like to instead see the core problem --\n> that *any* ambient authentication used by a proxy is inherently risky\n> -- exposed as a highly visible concept in the config, so that it's\n> hard to make mistakes.\n\nI find the concept of \"ambient authentication\" problematic. I don't\nknow exactly what you mean by it. I hope you'll tell me, but I think\nthat I won't like it even after I know, because as I said before, it's\ndifficult to know why anyone else makes a decision, and asking an\nuntrusted third-party why they're deciding something is sketchy at\nbest. I think that the problems we have in this area can be solved by\neither (a) restricting the open proxy to be less open or (b)\nencouraging people to authenticate users in some way that won't admit\nconnections from an open proxy. The former needs to be configurable by\nthe DBA, and the latter is also a configuration choice by the DBA. We\ncan provide tools here that make it less likely that people will shoot\nthemselves in the foot, and we can ship default configurations that\nreduce the chance of inadvertent foot-shooting, and we can write\ndocumentation that says \"don't shoot yourself in the foot,\" but we\ncannot actually prevent people from shooting themselves in the foot\nexcept, perhaps, by massively nerfing the capabilities of the system.\n\nWhat I was thinking about in terms of a \"reverse pg_hba.conf\" was\nsomething in the vein of, e.g.:\n\nSOURCE_COMPONENT SOURCE_DATABASE SOURCE_USER DESTINATION_SUBNET\nDESTINATION_DATABASE DESTINATION_USER OPTIONS ACTION\n\ne.g.\n\nall all all local all all - deny # block access through UNIX sockets\nall all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\n\nOr:\n\npostgres_fdw all all all all all authentication=cleartext,md5,sasl\nallow # allow postgres_fdw with password-ish authentication\n\nDisallowing loopback connections feels quite tricky. You could use\n127.anything.anything.anything, but you could also loop back via IPv6,\nor you could loop back via any interface. But you can't use\nsubnet-based ACLs to rule out loop backs through IP/IPv6 interfaces\nunless you know what all your system's own IPs are. Maybe that's an\nargument in favor of having a dedicated deny-loopback facility built\ninto the system instead of relying on IP ACLs. But I am not sure that\nreally works either: how sure are we that we can discover all of the\nlocal IP addresses? Maybe it doesn't matter anyway, since the point is\njust to disallow anything that would be likely to use \"trust\" or\n\"ident\" authentication, and that's probably not going to include any\nnon-loopback network interfaces. But ... is that true in general? What\nabout on Windows?\n\n> - I'm inherently skeptical of solutions that require all clients --\n> proxies, in this case -- to be configured correctly in order for a\n> server to be able to protect itself. (But I also have a larger\n> appetite for security options that break compatibility when turned on.\n> :D)\n\nI (still) don't think that restricting the proxy is required, but you\ncan't both not restrict the proxy and also allow passwordless loopback\nsuperuser connections. You have to pick one or the other. The reason I\nkeep harping on the role of the DBA is that I don't think we can make\nthat choice unilaterally on behalf of everyone. We've tried doing that\nwith the current rules and we've discussed the weaknesses of that\napproach already.\n\n> > I don't think the logon trigger thing is all *that* hypothetical. We\n> > don't have it yet, but there have been patches proposed repeatedly for\n> > many years.\n>\n> Okay. I think this thread has applicable lessons -- if connection\n> establishment itself leads to side effects, all actors in the\n> ecosystem (bouncers, proxies) have to be hardened against making those\n> connections passively. I know we're very different from HTTP, but it\n> feels similar to their concept of method safety and the consequences\n> of violating it.\n\nI am not familiar with that concept in detail but that sounds right to me.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 24 Jan 2023 15:04:15 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Mon, Jan 23, 2023 at 3:50 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> I believe your patch conflates two use cases:\n>\n> (A) Tightly-coupled servers that are managed by the administrator. In\n> this case, there are a finite number of connection strings to make, and\n> the admin knows about all of them. Validation is a poor solution for\n> this use case, because we get into the weeds trying to figure out\n> what's safe or not, overriding the admin's better judgement in some\n> cases and letting through connection strings that might be unsafe. A\n> much better solution is to simply declare the connection strings as\n> some kind of object (perhaps a SERVER object), and hand out privileges\n> or inherit them from a predefined role. Having connection string\n> objects is also just a better UI: it allows changes to connection\n> strings over time to adapt to changing security needs, and allows a\n> simple name that is much easier to type and read.\n>\n> (B) Loosely-coupled servers that the admin doesn't know about, but\n> which might be perfectly safe to access. Validation is useful here, but\n> it's a long road of fine-grained privileges around acceptable hosts,\n> IPs, authentication types, file access, password sources, password\n> protocols, connection options, etc. The right solution here is to\n> identify the sub-usecases of loosely-coupled servers, and enable them\n> (with the appropriate controls) one at a time. Arguably, that's already\n> what's happened by demanding a password (even if we don't like the\n> mechanism, it does seem to work for some important cases).\n>\n> Is your patch targeted at use case (A), (B), or both?\n\nI suppose that I would say that the patch is a better fit for (B),\nbecause I'm not proposing to add any kind of intermediate object of\nthe type you postulate in (A). However, I don't really agree with the\nway you've split this up, either. It seems to me that the relevant\nquestion isn't \"are the servers tightly coupled?\" but rather \"could\nsome user make a mess if we let them use any arbitrary connection\nstring?\".\n\nIf you're running all of the machines involved on a private network\nthat is well-isolated from the Internet and in which only trusted\nactors operate, you could use what I'm proposing here for either (A)\nor (B) and it would be totally fine. If your server is sitting out on\nthe public Internet and is adequately secured against malicious\nloopback connections, you could also probably use it for either (A) or\n(B), unless you've got users who are really shady and you're worried\nthat the outbound connections that they make from your machine might\nget you into trouble, in which case you probably can't use it for\neither (A) or (B). Basically, the patch is suitable for cases where\nyou don't really need to restrict what connection strings people can\nuse, and unsuitable for cases where you do, but that doesn't have much\nto do with whether the servers involved are loosely or tightly\ncoupled.\n\nI think that you're basically trying to make an argument that some\nsort of complex outbound connection filtering is mandatory, and I\nstill don't really agree with that. We ship postgres_fdw with\nsomething extremely minimal - just a requirement that the password get\nused - and the same for dblink. I think those rules suck and are\nprobably bad and insecure in quite a number of cases, and overly\nstrict in others, but I can think of no reason why CREATE SUBSCRIPTION\nshould be held to a higher standard than anything else. The\nconnections that you can make using CREATE SUBSCRIPTION are strictly\nweaker than the ones you can make with dblink, which permits arbitrary\nSQL execution. It cannot be right to suppose that a less-exploitable\nsystem needs to be held to a higher security standard than a similar\nbut more-exploitable system.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 24 Jan 2023 17:00:52 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 1/24/23 12:04, Robert Haas wrote:\n> I find the concept of \"ambient authentication\" problematic. I don't\n> know exactly what you mean by it. I hope you'll tell me,\n\nSure: Ambient authority [1] means that something is granted access based\non some aspect of its existence that it can't remove (or even\nnecessarily enumerate). Up above, when you said \"I cannot choose not to\nbe myself,\" that's a clear marker that ambient authority is involved.\nExamples of ambient authn/z factors might include an originating IP\naddress, the user ID of a connected peer process, the use of a loopback\ninterface, a GPS location, and so on. So 'peer' and 'ident' are ambient\nauthentication methods.\n\nAnd, because I think it's useful, I'll extend the definition to include\nprivileges that _could_ be dropped by a proxy, but in practice are\nincluded because there's no easy way not to. Examples for libpq include\nthe automatic use of the client certificate in ~/.postgresql, or any\nKerberos credentials available in the local user cache. (Or even a\nPGPASSWORD set up and forgotten by a DBA.)\n\nAmbient authority is closely related to the confused deputy problem [2],\nand the proxy discussed here is a classic confused deputy. The proxy\ndoesn't know that a core piece of its identity has been used to\nauthenticate the request it's forwarding. It can't choose its IP\naddress, or its user ID.\n\nI'm most familiar with this in the context of HTTP, cookie-/IP-based\nauthn, and cross-site request forgeries. Whenever someone runs a local\nweb server with no authentication and says \"it's okay! we only respond\nto requests from the local host!\" they're probably about to be broken\nopen by the first person to successfully reflect a request through the\nvictim's (very local) web browser.\n\nWays to mitigate or solve this problem (that I know of) include\n\n1) Forwarding the original ambient context along with the request, so\nthe server can check it too. HTTP has the Origin header, so a browser\ncan say, \"This request is not coming from my end user; it's coming from\na page controlled by example.org. You can't necessarily treat attached\ncookies like they're authoritative.\" The PROXY protocol lets a proxy\nforward several ambient factors, including the originating IP address\n(or even the use of a UNIX socket) and information about the original\nTLS context.\n\n2) Explicitly combining the request with the proof of authority needed\nto make it, as in capability-based security [3]. Some web frameworks\npush secret \"CSRF tokens\" into URLs for this purpose, to tangle the\nauthorization into the request itself [4]. I'd argue that the \"password\nrequirement\" implemented by postgres_fdw and discussed upthread was an\nattempt at doing this, to try to ensure that the authentication comes\nfrom the user explicitly and not from the proxy. It's just not very strong.\n\n(require_auth would strengthen it quite a bit; a major feature of that\npatchset is to explicitly name the in-band authentication factors that a\nserver is allowed to pull out of a client. It's still not strong enough\nto make a true capability, for one because it's client-side only. But as\nlong as servers don't perform actions on behalf of users upon\nconnection, that's pretty good in practice.)\n\n3) Dropping as many implicitly-held privileges as possible before making\na request. This doesn't solve the problem but may considerably reduce\nthe practical attack surface. For example, if browsers didn't attach\ntheir user's cookies to cross-origin requests, cross-site request\nforgeries would probably be considerably less dangerous (and, in the\nyears since I left the space, it looks like browsers have finally\nstopped doing this by default). Upthread, Andres suggested disabling the\ndefault inclusion of client certs and GSS creds, and I would extend that\nto include really *anything* pulled in from the environment. Make the\nDBA explicitly allow those things.\n\n> but I think\n> that I won't like it even after I know, because as I said before, it's\n> difficult to know why anyone else makes a decision, and asking an\n> untrusted third-party why they're deciding something is sketchy at\n> best.\n\nI think that's a red herring. Setting aside that you can, in fact, prove\nthat the server has authenticated you (e.g. require_auth=scram-sha-256\nin my proposed patchset), I don't think \"untrusted servers, that we\ndon't control, doing something stupid\" is a very useful thing to focus\non. We're trying to secure the case where a server *is* authenticating\nus, using known useful factors, but those factors have been co-opted by\nan attacker via a proxy.\n\n> I think that the problems we have in this area can be solved by\n> either (a) restricting the open proxy to be less open or (b)\n> encouraging people to authenticate users in some way that won't admit\n> connections from an open proxy.\n\n(a) is an excellent mitigation, and we should do it. (b) starts getting\nshaky because I think peer auth is actually a very reasonable choice for\nmany people. So I hope we can also start solving the underlying problem\nwhile we implement (a).\n\n> we\n> cannot actually prevent people from shooting themselves in the foot\n> except, perhaps, by massively nerfing the capabilities of the system.\n\nBut I thought we already agreed that most DBAs do not want a massively\ncapable proxy? I don't think we have to massively nerf the system, but\nlet's say we did. Would that really be unacceptable for this use case?\n\n(You're still driving hard down the \"it's impossible for us to securely\nhandle both cases at the same time\" path. I don't think that's true from\na technical standpoint, because we hold nearly total control of the\nprotocol. I think we're in a much easier situation than HTTP was.)\n\n> What I was thinking about in terms of a \"reverse pg_hba.conf\" was\n> something in the vein of, e.g.:\n> \n> SOURCE_COMPONENT SOURCE_DATABASE SOURCE_USER DESTINATION_SUBNET\n> DESTINATION_DATABASE DESTINATION_USER OPTIONS ACTION\n> \n> e.g.\n> \n> all all all local all all - deny # block access through UNIX sockets\n> all all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\n> \n> Or:\n> \n> postgres_fdw all all all all all authentication=cleartext,md5,sasl\n> allow # allow postgres_fdw with password-ish authentication\n\nI think this style focuses on absolute configuration flexibility at the\nexpense of usability. It obfuscates the common use cases. (I have the\nexact same complaint about our HBA and ident configs, so I may be\nfighting uphill.)\n\nHow should a DBA decide what is correct, or audit a configuration they\ninherited from someone else? What makes it obvious why a proxy should\nrequire cleartext auth instead of peer auth (especially since peer auth\nseems to be inherently better, until you've read this thread)?\n\nI'd rather the configuration focus on the pieces of a proxy's identity\nthat can be assumed by a client. For example, if the config has an\noption for \"let a client steal the proxy's user ID\", and it's off by\ndefault, then we've given the problem a name. DBAs can educate\nthemselves on it.\n\nAnd if that option is off, then the implementation knows that\n\n1) If the client has supplied explicit credentials and we can force the\nserver to use them, we're safe.\n2) If the DBA says they're not running an ident server, or we can force\nthe server not to use ident authn, or the DBA pinky-swears that that\nserver isn't using ident authn, all IP connections are additionally safe.\n3) If we have a way to forward the client's \"origin\" and we know that\nthe server will pay attention to it, all UNIX socket connections are\nadditionally safe.\n4) Any *future* authentication method we add later needs to be\nrestricted in the same way.\n\nShould we allow the use of our default client cert? the Kerberos cache?\npasswords from the environment? All these are named and off by default.\nDBAs can look through those options and say \"oh, yeah, that seems like a\nreally bad idea because we have this one server over here...\" And we\n(the experts) now get to make the best decisions we can, based on a\nDBA's declared intent, so the implementation gets to improve over time.\n> Disallowing loopback connections feels quite tricky. You could use\n> 127.anything.anything.anything, but you could also loop back via IPv6,\n> or you could loop back via any interface. But you can't use\n> subnet-based ACLs to rule out loop backs through IP/IPv6 interfaces\n> unless you know what all your system's own IPs are. Maybe that's an\n> argument in favor of having a dedicated deny-loopback facility built\n> into the system instead of relying on IP ACLs. But I am not sure that\n> really works either: how sure are we that we can discover all of the\n> local IP addresses?\n\nWell, to follow you down that road a little bit, I think that a DBA that\nhas set up `samehost ... trust` in their HBA is going to expect a\ncorresponding concept here, and it seems important for us to use an\nidentical implementation of samehost and samenet.\n\nBut I don't really want to follow you down that road, because I think\nyou illustrated my point yourself. You're already thinking about making\nDisallowing Loopback Connections a first-class concept, but then you\nimmediately said\n\n> Maybe it doesn't matter anyway, since the point is\n> just to disallow anything that would be likely to use \"trust\" or\n> \"ident\" authentication\n\nI'd rather we enshrine that -- the point -- in the configuration, and\nhave the proxy disable everything that can't provably meet that intent.\n\nThanks,\n--Jacob\n\n[1] https://en.wikipedia.org/wiki/Ambient_authority\n[2] https://en.wikipedia.org/wiki/Confused_deputy_problem\n[3] https://en.wikipedia.org/wiki/Capability-based_security\n[4] https://www.rfc-editor.org/rfc/rfc6265#section-8.2\n\n\n","msg_date":"Wed, 25 Jan 2023 15:22:02 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Tue, 2023-01-24 at 17:00 -0500, Robert Haas wrote:\n> It seems to me that the relevant\n> question isn't \"are the servers tightly coupled?\" but rather \"could\n> some user make a mess if we let them use any arbitrary connection\n> string?\".\n\nThe split I created is much easier for an admin to answer: is the list\nof servers finite, or can users connect to new servers the admin isn't\neven aware of? If it's a finite list, I feel there's a much better\nsolution with both security and UI benefits.\n\nWith your question, I'm not entirely clear if that's a question that we\nalready have an answer for (require a password parameter), or that we\nwill answer in this thread, or that the admin will answer.\n\n> unless you've got users who are really shady \n\nOr compromised. Unfortunately, a role that's creating subscriptions has\na lot of surface area for escalation-of-privilege attacks, because they\nhave to trust all the owners of all the tables the subscriptions write\nto.\n\n\n> I think that you're basically trying to make an argument that some\n> sort of complex outbound connection filtering is mandatory\n\nNo, I'm not asking for the validation to be more complex.\n\nI believe use case (A) is a substantial use case, and I'd like to leave\nspace in the user interface to solve it a much better way than\nconnection string validation can offer. But to solve use case (A), we\nneed to separate the ability to create a subscription from the ability\nto create a connection string.\n\nRight now you see those as the same because they are done at the same\ntime in the same command; but I don't see it that way, because I had\nplans to allow a variant of CREATE SUBSCRIPTION that uses foreign\nservers. That plan would be consistent with dblink and postgres_fdw,\nwhich already allow specifying foreign servers.\n\nI propose that we have two predefined roles: pg_create_subscription,\nand pg_create_connection. If creating a subscription with a connection\nstring, you'd need to be a member of both roles. But to create a\nsubscription with a server object, you'd just need to be a member of\npg_create_subscription and have the USAGE privilege on the server\nobject.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Wed, 25 Jan 2023 19:45:09 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Jan 25, 2023 at 10:45 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> I propose that we have two predefined roles: pg_create_subscription,\n> and pg_create_connection. If creating a subscription with a connection\n> string, you'd need to be a member of both roles. But to create a\n> subscription with a server object, you'd just need to be a member of\n> pg_create_subscription and have the USAGE privilege on the server\n> object.\n\nI have no issue with that as a long-term plan. However, I think that\nfor right now we should just introduce pg_create_subscription. It\nwould make sense to add pg_create_connection in the same patch that\nadds a CREATE CONNECTION command (or whatever exact syntax we end up\nwith) -- and that patch can also change CREATE SUBSCRIPTION to require\nboth privileges where a connection string is specified directly.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 26 Jan 2023 09:43:09 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2023-01-26 at 09:43 -0500, Robert Haas wrote:\n> I have no issue with that as a long-term plan. However, I think that\n> for right now we should just introduce pg_create_subscription. It\n> would make sense to add pg_create_connection in the same patch that\n> adds a CREATE CONNECTION command (or whatever exact syntax we end up\n> with) -- and that patch can also change CREATE SUBSCRIPTION to\n> require\n> both privileges where a connection string is specified directly.\n\nI assumed it would be a problem to say that pg_create_subscription was\nenough to create a subscription today, and then later require\nadditional privileges (e.g. pg_create_connection).\n\nIf that's not a problem, then this sounds fine with me.\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Thu, 26 Jan 2023 09:36:11 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Jan 26, 2023 at 12:36 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Thu, 2023-01-26 at 09:43 -0500, Robert Haas wrote:\n> > I have no issue with that as a long-term plan. However, I think that\n> > for right now we should just introduce pg_create_subscription. It\n> > would make sense to add pg_create_connection in the same patch that\n> > adds a CREATE CONNECTION command (or whatever exact syntax we end up\n> > with) -- and that patch can also change CREATE SUBSCRIPTION to\n> > require\n> > both privileges where a connection string is specified directly.\n>\n> I assumed it would be a problem to say that pg_create_subscription was\n> enough to create a subscription today, and then later require\n> additional privileges (e.g. pg_create_connection).\n>\n> If that's not a problem, then this sounds fine with me.\n\nWonderful! I'm working on a patch, but due to various distractions,\nit's not done yet.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 26 Jan 2023 15:55:13 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Jan 19, 2023 at 8:46 PM Andres Freund <andres@anarazel.de> wrote:\n> > If we already had (or have) that logic someplace else, it would\n> > probably make sense to reuse it\n>\n> We hve. See at least postgres_fdw's check_conn_params(), dblink's\n> dblink_connstr_check() and dblink_security_check().\n\nIn the patch I posted previously, I had some other set of checks, more\nor less along the lines suggested by Jeff. I looked into revising that\napproach and making the behavior match exactly what we do in those\nplaces instead. I find that it breaks 027_nosuperuser.pl.\nSpecifically, where without the patch I get \"ok 6 - nosuperuser admin\nwith all table privileges can replicate into unpartitioned\", with the\npatch it goes boom, because the subscription can't connect any more\ndue to the password requirement.\n\nAt first, I found it a bit tempting to see this as a further\nindication that the force-a-password approach is not the right idea,\nbecause the test case clearly memorializes a desire *not* to require a\npassword in this situation. However, the loopback-to-superuser attack\nis just as viable for subscription as it in other cases, and my\nprevious patch would have done nothing to block it. So what I did\ninstead is add a password_required attribute, just like what\npostgres_fdw has. As in the case of postgres_fdw, the actual rule is\nthat if the attribute is false, a password is not required, and if the\nattribute is true, a password is required unless you are a superuser.\nIf you're a superuser, it still isn't. This is a slightly odd set of\nsemantics but it has precedent and practical advantages. Also, as in\nthe case of postgres_fdw, only a superuser can set\npassword_required=false, and a subscription that has that setting can\nonly be modified by a superuser, no matter who owns it.\n\nEven though I hate the require-a-password stuff with the intensity of\na thousand suns, I think this is better than the previous patch,\nbecause it's more consistent with what we do elsewhere and because it\nblocks the loopback-connection-to-superuser attack. I think we\n*really* need to develop a better system for restricting proxied\nconnections (no matter how proxied) and I hope that we do that soon.\nBut inventing something for this purpose that differs from what we do\nelsewhere will make that task harder, not easier.\n\nThoughts?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com","msg_date":"Fri, 27 Jan 2023 14:42:01 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Jan 25, 2023 at 6:22 PM Jacob Champion <jchampion@timescale.com> wrote:\n> Sure: Ambient authority [1] means that something is granted access based\n> on some aspect of its existence that it can't remove (or even\n> necessarily enumerate). Up above, when you said \"I cannot choose not to\n> be myself,\" that's a clear marker that ambient authority is involved.\n> Examples of ambient authn/z factors might include an originating IP\n> address, the user ID of a connected peer process, the use of a loopback\n> interface, a GPS location, and so on. So 'peer' and 'ident' are ambient\n> authentication methods.\n\nOK.\n\n> 1) Forwarding the original ambient context along with the request, so\n> the server can check it too.\n\nRight, so a protocol extension. Reasonable idea, but a big lift. Not\nonly do you need everyone to be running a new enough version of\nPostgreSQL, but existing proxies like pgpool and pgbouncer need\nupdates, too.\n\n> 2) Explicitly combining the request with the proof of authority needed\n> to make it, as in capability-based security [3].\n\nAs far as I can see, that link doesn't address how you'd make this\napproach work across a network.\n\n> 3) Dropping as many implicitly-held privileges as possible before making\n> a request. This doesn't solve the problem but may considerably reduce\n> the practical attack surface.\n\nRight. I definitely don't object to this kind of approach, but I don't\nthink it can ever be sufficient by itself.\n\n> > e.g.\n> >\n> > all all all local all all - deny # block access through UNIX sockets\n> > all all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\n> >\n> > Or:\n> >\n> > postgres_fdw all all all all all authentication=cleartext,md5,sasl\n> > allow # allow postgres_fdw with password-ish authentication\n>\n> I think this style focuses on absolute configuration flexibility at the\n> expense of usability. It obfuscates the common use cases. (I have the\n> exact same complaint about our HBA and ident configs, so I may be\n> fighting uphill.)\n\nThat's probably somewhat true, but on the other hand, it also is more\npowerful than what you're describing. In your system, is there some\nway the DBA can say \"hey, you can connect to any of the machines on\nthis list of subnets, but nothing else\"? Or equally, \"hey, you may NOT\nconnect to any machine on this list of subnets, but anything else is\nfine\"? Or \"you can connect to these subnets without SSL, but if you\nwant to talk to anything else, you need to use SSL\"? I would feel a\nbit bad saying that those are just use cases we don't care about. Most\npeople likely wouldn't use that kind of flexibility, so maybe it\ndoesn't really matter, but it seems kind of nice to have. Your idea\nseems to rely on us being able to identify all of the policies that a\nuser is likely to want and give names to each one, and I don't feel\nvery confident that that's realistic. But maybe I'm misinterpreting\nyour idea?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 27 Jan 2023 16:08:38 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"Hi,\n\nOn 2023-01-27 14:42:01 -0500, Robert Haas wrote:\n> At first, I found it a bit tempting to see this as a further\n> indication that the force-a-password approach is not the right idea,\n> because the test case clearly memorializes a desire *not* to require a\n> password in this situation. However, the loopback-to-superuser attack\n> is just as viable for subscription as it in other cases, and my\n> previous patch would have done nothing to block it.\n\nHm, compared to postgres_fdw, the user has far less control over what's\nhappening using that connection. Is there a way a subscription owner can\ntrigger evaluation of near-arbitrary SQL on the publisher side?\n\n\n> So what I did instead is add a password_required attribute, just like what\n> postgres_fdw has. As in the case of postgres_fdw, the actual rule is that if\n> the attribute is false, a password is not required, and if the attribute is\n> true, a password is required unless you are a superuser. If you're a\n> superuser, it still isn't. This is a slightly odd set of semantics but it\n> has precedent and practical advantages. Also, as in the case of\n> postgres_fdw, only a superuser can set password_required=false, and a\n> subscription that has that setting can only be modified by a superuser, no\n> matter who owns it.\n\nI started out asking what benefits it provides to own a subscription one\ncannot modify. But I think it is a good capability to have, to restrict the\nset of relations that replication could target. Although perhaps it'd be\nbetter to set the \"replay user\" as a separate property on the subscription?\n\nDoes owning a subscription one isn't allowed to modify useful outside of that?\n\n\n\n> Even though I hate the require-a-password stuff with the intensity of\n> a thousand suns, I think this is better than the previous patch,\n> because it's more consistent with what we do elsewhere and because it\n> blocks the loopback-connection-to-superuser attack. I think we\n> *really* need to develop a better system for restricting proxied\n> connections (no matter how proxied) and I hope that we do that soon.\n> But inventing something for this purpose that differs from what we do\n> elsewhere will make that task harder, not easier.\n> \n> Thoughts?\n\nI think it's reasonable to mirror behaviour from elsewhere, and it'd let us\nhave this feature relatively soon - I think it's a common need to do this as a\nnon-superuser. It's IMO a very good idea to not subscribe as a superuser, even\nif set up by a superuser...\n\nBut I also would understand if you / somebody else chose to focus on\nimplementing a less nasty connection model.\n\n\n> Subject: [PATCH v2] Add new predefined role pg_create_subscriptions.\n\nMaybe a daft question:\n\nHave we considered using a \"normal grant\", e.g. on the database, instead of a\nrole? Could it e.g. be useful to grant a user the permission to create a\nsubscription in one database, but not in another?\n\n\n> @@ -1039,6 +1082,16 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,\n> \n> \tsub = GetSubscription(subid, false);\n> \n> +\t/*\n> +\t * Don't allow non-superuser modification of a subscription with\n> +\t * password_required=false.\n> +\t */\n> +\tif (!sub->passwordrequired && !superuser())\n> +\t\tereport(ERROR,\n> +\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n> +\t\t\t\t\t\t errmsg(\"password_required=false is superuser-only\"),\n> +\t\t\t\t\t\t errhint(\"Subscriptions with the password_required option set to false may only be created or modified by the superuser.\")));\n> +\n> \t/* Lock the subscription so nobody else can do anything with it. */\n> \tLockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);\n\nThe subscription code already does ownership checks before locking and now\nthere's also the passwordrequired before. Is it possible that this could open\nup some sort of race? Could e.g. the user change the ownership to the\nsuperuser in one session, do an ALTER in the other?\n\nIt looks like your change won't increase the danger of that, as the\nsuperuser() check just checks the current users permissions.\n\n\n> @@ -180,6 +180,13 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,\n> \tif (PQstatus(conn->streamConn) != CONNECTION_OK)\n> \t\tgoto bad_connection_errmsg;\n> \n> +\tif (must_use_password && !PQconnectionUsedPassword(conn->streamConn))\n> +\t\tereport(ERROR,\n> +\t\t\t\t(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),\n> +\t\t\t\t errmsg(\"password is required\"),\n> +\t\t\t\t errdetail(\"Non-superuser cannot connect if the server does not request a password.\"),\n> +\t\t\t\t errhint(\"Target server's authentication method must be changed.\")));\n> +\n\nThe documentation of libpqrcv_connect() says that:\n * Returns NULL on error and fills the err with palloc'ed error message.\n\nand throwing an error like that will at the very least leak the connection,\nfd, fd reservation. Which I just had fixed :). At the very least you'd need to\ncopy the stuff that \"bad_connection:\" does.\n\n\nI did wonder whether we should make libpqrcv_connect() use errsave() to return\nerrors. Or whether we should make libpqrcv register a memory context reset\ncallback that'd close the libpq connection.\n\n\n> /*\n> - * Validate connection info string (just try to parse it)\n> + * Validate connection info string, and determine whether it might cause\n> + * local filesystem access to be attempted.\n> + *\n> + * If the connection string can't be parsed, this function will raise\n> + * an error and will not return. If it can, it will return true if this\n> + * connection string specifies a password and false otherwise.\n> */\n> -static void\n> +static bool\n> libpqrcv_check_conninfo(const char *conninfo)\n\nThat is a somewhat odd API. Why does it throw for some things, but not\nothers? Seems a bit cleaner to pass in a parameter indicating whether it\nshould throw when not finding a password? Particularly because you already\npass that to walrcv_connect().\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Fri, 27 Jan 2023 13:09:11 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Jan 27, 2023 at 4:09 PM Andres Freund <andres@anarazel.de> wrote:\n> Hm, compared to postgres_fdw, the user has far less control over what's\n> happening using that connection. Is there a way a subscription owner can\n> trigger evaluation of near-arbitrary SQL on the publisher side?\n\nI'm not aware of one, but what I think it would let you do is\nexfiltrate data you're not entitled to see.\n\n> I started out asking what benefits it provides to own a subscription one\n> cannot modify. But I think it is a good capability to have, to restrict the\n> set of relations that replication could target. Although perhaps it'd be\n> better to set the \"replay user\" as a separate property on the subscription?\n\nThat's been proposed previously, but for reasons I don't quite\nremember it seems not to have happened. I don't think it achieved\nconsensus.\n\n> Does owning a subscription one isn't allowed to modify useful outside of that?\n\nUh, possibly that's a question for Mark or Jeff. I don't know. I can't\nsee what they would be, but I just work here.\n\n> Maybe a daft question:\n>\n> Have we considered using a \"normal grant\", e.g. on the database, instead of a\n> role? Could it e.g. be useful to grant a user the permission to create a\n> subscription in one database, but not in another?\n\nPotentially, but I didn't think we'd want to burn through permissions\nbits that fast, even given 7b378237aa805711353075de142021b1d40ff3b0.\nStill, if the consensus is otherwise, I can change it. Then I guess\nwe'd end up with GRANT CREATE ON DATABASE and GRANT CREATE\nSUBSCRIPTION ON DATABASE, which I'm sure wouldn't be confusing at all.\n\nOr, another thought, maybe this should be checking for CREATE on the\ncurrent database + also pg_create_subscription. That seems like it\nmight be the right idea, actually.\n\n> The subscription code already does ownership checks before locking and now\n> there's also the passwordrequired before. Is it possible that this could open\n> up some sort of race? Could e.g. the user change the ownership to the\n> superuser in one session, do an ALTER in the other?\n>\n> It looks like your change won't increase the danger of that, as the\n> superuser() check just checks the current users permissions.\n\nI'm not entirely clear whether there's a hazard there. If there is, I\nthink we could fix it by moving the LockSharedObject call up higher,\nabove object_ownercheck. The only problem with that is it lets you\nlock an object on which you have no permissions: see\n2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd\nneed an analogue of RangeVarGetRelidExtended.\n\n> and throwing an error like that will at the very least leak the connection,\n> fd, fd reservation. Which I just had fixed :). At the very least you'd need to\n> copy the stuff that \"bad_connection:\" does.\n\nOK.\n\n> I did wonder whether we should make libpqrcv_connect() use errsave() to return\n> errors. Or whether we should make libpqrcv register a memory context reset\n> callback that'd close the libpq connection.\n\nYeah. Using errsave() might be better, but not sure I want to tackle\nthat just now.\n\n> That is a somewhat odd API. Why does it throw for some things, but not\n> others? Seems a bit cleaner to pass in a parameter indicating whether it\n> should throw when not finding a password? Particularly because you already\n> pass that to walrcv_connect().\n\nWill look into that.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 27 Jan 2023 16:35:11 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-27 16:35:11 -0500, Robert Haas wrote:\n> > Maybe a daft question:\n> >\n> > Have we considered using a \"normal grant\", e.g. on the database, instead of a\n> > role? Could it e.g. be useful to grant a user the permission to create a\n> > subscription in one database, but not in another?\n> \n> Potentially, but I didn't think we'd want to burn through permissions\n> bits that fast, even given 7b378237aa805711353075de142021b1d40ff3b0.\n> Still, if the consensus is otherwise, I can change it.\n\nI don't really have an opinion on what's better. I looked briefly whether\nthere was discussion around ithis but I didn't see anything.\n\npg_create_subcription feels a bit different than most of the other pg_*\nroles. For most of those there is no schema object to tie permissions to. But\nhere there is.\n\nBut I think there's good arguments against a GRANT approach, too. GRANT ALL ON\nDATABASE would suddenly be dangerous. How does it interact with database\nownership? Etc.\n\n\n> Then I guess we'd end up with GRANT CREATE ON DATABASE and GRANT CREATE\n> SUBSCRIPTION ON DATABASE, which I'm sure wouldn't be confusing at all.\n\nHeh. I guess it could just be GRANT SUBSCRIBE.\n\n\n\n> Or, another thought, maybe this should be checking for CREATE on the\n> current database + also pg_create_subscription. That seems like it\n> might be the right idea, actually.\n\nYes, that seems like a good idea.\n\n\n\n> > The subscription code already does ownership checks before locking and now\n> > there's also the passwordrequired before. Is it possible that this could open\n> > up some sort of race? Could e.g. the user change the ownership to the\n> > superuser in one session, do an ALTER in the other?\n> >\n> > It looks like your change won't increase the danger of that, as the\n> > superuser() check just checks the current users permissions.\n> \n> I'm not entirely clear whether there's a hazard there.\n\nI'm not at all either. It's just a code pattern that makes me anxious - I\nsuspect there's a few places it makes us more vulnerable.\n\n\n> If there is, I think we could fix it by moving the LockSharedObject call up\n> higher, above object_ownercheck. The only problem with that is it lets you\n> lock an object on which you have no permissions: see\n> 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\n> analogue of RangeVarGetRelidExtended.\n\nYea, we really should have something like RangeVarGetRelidExtended() for other\nkinds of objects. It'd take a fair bit of work / time to use it widely, but\nit'll take even longer if we start in 5 years ;)\n\nPerhaps the bulk of RangeVarGetRelidExtended() could be generalized by having\na separate name->oid lookup callback?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Fri, 27 Jan 2023 14:00:35 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 27, 2023, at 1:35 PM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n>> I started out asking what benefits it provides to own a subscription one\n>> cannot modify. But I think it is a good capability to have, to restrict the\n>> set of relations that replication could target. Although perhaps it'd be\n>> better to set the \"replay user\" as a separate property on the subscription?\n> \n> That's been proposed previously, but for reasons I don't quite\n> remember it seems not to have happened. I don't think it achieved\n> consensus.\n> \n>> Does owning a subscription one isn't allowed to modify useful outside of that?\n> \n> Uh, possibly that's a question for Mark or Jeff. I don't know. I can't\n> see what they would be, but I just work here.\n\nIf the owner cannot modify the subscription, then the owner degenerates into a mere \"run-as\" user. Note that this isn't how things work now, and even if we disallowed owners from modifying the connection string, there would still be other attributes the owner could modify, such as the set of publications subscribed.\n\n\nMore generally, my thinking on this thread is that there needs to be two nosuperuser roles: A higher privileged role which can create a subscription, and a lower privileged role serving the \"run-as\" function. Those shouldn't be the same, because the \"run-as\" concept doesn't logically need to have subscription creation power, and likely *shouldn't* have that power. Depending on which sorts of attributes a subscription object has, such as the connection string, the answer differs for whether the owner/\"run-as\" user should get to change those attributes. One advantage of Jeff's idea of using a server object rather than a string is that it becomes more plausibly safe to allow the subscription owner to make changes to that attribute of the subscription.\n\n\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Fri, 27 Jan 2023 14:56:04 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Jan 27, 2023 at 5:56 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> If the owner cannot modify the subscription, then the owner degenerates into a mere \"run-as\" user. Note that this isn't how things work now, and even if we disallowed owners from modifying the connection string, there would still be other attributes the owner could modify, such as the set of publications subscribed.\n\nThe proposed patch blocks every form of ALTER SUBSCRIPTION if\npassword_required false is set and you aren't a superuser. Is there\nsome other DML command that could be used to modify the set of\npublications subscribed?\n\n> More generally, my thinking on this thread is that there needs to be two nosuperuser roles: A higher privileged role which can create a subscription, and a lower privileged role serving the \"run-as\" function. Those shouldn't be the same, because the \"run-as\" concept doesn't logically need to have subscription creation power, and likely *shouldn't* have that power. Depending on which sorts of attributes a subscription object has, such as the connection string, the answer differs for whether the owner/\"run-as\" user should get to change those attributes. One advantage of Jeff's idea of using a server object rather than a string is that it becomes more plausibly safe to allow the subscription owner to make changes to that attribute of the subscription.\n\nThere's some question in my mind about what these different mechanisms\nare intended to accomplish.\n\nOn a technical level, I think that the idea of having a separate\nobjection for the connection string vs. the subscription itself is\nperfectly sound, and to repeat what I said earlier, if someone wants\nto implement that, cool. I also agree that it has the advantage that\nyou specify, namely, that someone can have rights to modify one of\nthose objects but not the other. What that lets you do is define a\nshort list of known systems and say, hey, you can replicate whatever\ntables you want with whatever options you want, but only between these\nsystems. I'm not quite sure what problem that solves, though.\n\n From my point of view, the two things that the superuser is most\nlikely to want to do are (1) control the replication setup themselves\nand delegate nothing to any non-superuser or (2) give a non-superuser\npretty much complete control over replication with just enough\nrestrictions to avoid letting them do things that would compromise\nsecurity, such as hacking the local superuser account. In other words,\nI expect that delegation of the logical replication configuration is\nusually going to be all or nothing. Jeff's system allows for a\nsituation where you want to delegate some stuff but not everything,\nand specifically where you want to dedicate control over the\nsubscription options and the tables being replicated, but not the\nconnection strings. To me, that feels like a bit of an awkward\nconfiguration; I don't really understand in what situation that\ndivision of responsibility would be particularly useful. I trust that\nJeff is proposing it because he knows of such a situation, but I don't\nknow what it is. I feel like, even if I wanted to let people use some\nconnection strings and not others, I'd probably want that control in\nsome form other than listing a specific list of allowable connection\nstrings -- I'd want to say things like \"you have to use SSL\" or \"no\nconnecting back to the local host,\" because that lets me enforce some\ngeneral organizational policy without having to care specifically\nabout how each subscription is being set up.\n\nUnfortunately, I have even less of an idea about what the run-as\nconcept is supposed to accomplish. I mean, at one level, I see it\nquite clearly: the user creating the subscription wants replication to\nhave restricted privileges when it's running, and so they make the\nrun-as user some role with fewer privileges than their own. Brilliant.\nBut then I get stuck: against what kind of attack does that actually\nprotect us? If I'm a high privilege user, perhaps even a superuser,\nand it's not safe to have logical replication running as me, then it\nseems like the security model of logical replication is fundamentally\nbusted and we need to fix that. It can't be right to say that if you\nhave 263 users in a database and you want to replicate the whole\ndatabase to some other node, you need 263 different subscriptions with\na different run-as user for each. You need to be able to run all of\nthat logical replication as the superuser or some other high-privilege\nuser and not end up with a security compromise. And if we suppose that\nthat already works and is safe, well then what's the case where I do\nneed a run-as user?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 30 Jan 2023 10:44:29 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 30, 2023, at 7:44 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> And if we suppose that\n> that already works and is safe, well then what's the case where I do\n> need a run-as user?\n\nA) Alice publishes tables, and occasionally adds new tables to existing publications.\n\nB) Bob manages subscriptions, and periodically runs \"refresh publication\". Bob also creates new subscriptions for people when a row is inserted into the \"please create a subscription for me\" table which Bob owns, using a trigger that Bob created on that table.\n\nC) Alice creates a \"please create a subscription for me\" table on the publishing database, adds lots of malicious requests, and adds that table to the publication.\n\nD) Bob replicates the table, fires the trigger, creates the malicious subscriptions, and starts replicating all that stuff, too.\n\nI think that having Charlie, not Bob, as the \"run-as\" user helps somewhere right around (D). \n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 30 Jan 2023 08:11:03 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 30, 2023 at 11:11 AM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> > On Jan 30, 2023, at 7:44 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> >\n> > And if we suppose that\n> > that already works and is safe, well then what's the case where I do\n> > need a run-as user?\n>\n> A) Alice publishes tables, and occasionally adds new tables to existing publications.\n>\n> B) Bob manages subscriptions, and periodically runs \"refresh publication\". Bob also creates new subscriptions for people when a row is inserted into the \"please create a subscription for me\" table which Bob owns, using a trigger that Bob created on that table.\n>\n> C) Alice creates a \"please create a subscription for me\" table on the publishing database, adds lots of malicious requests, and adds that table to the publication.\n>\n> D) Bob replicates the table, fires the trigger, creates the malicious subscriptions, and starts replicating all that stuff, too.\n>\n> I think that having Charlie, not Bob, as the \"run-as\" user helps somewhere right around (D).\n\nI suppose it does, but I have some complaints.\n\nFirst, it doesn't seem to make a lot of sense to have one person\nmanaging the publications and someone else managing the subscriptions,\nand especially if those parties are mutually untrusting. I can't think\nof any real reason to set things up that way. Sure, you could, but why\nwould you? You could, equally, decide that one member of your\nhousehold was going to decide what's for dinner every night, and some\nother member of your household was going to decide what gets purchased\nat the grocery store each week. If those two people exercise their\nresponsibilities without tight coordination, or with hostile intent\ntoward each other, things are going to go badly, but that's not an\nargument for putting a combination lock on the flour canister. It's an\nargument for getting along better, or not having such a dumb system in\nthe first place. I don't quite see how the situation you postulate in\n(A) and (B) is any different. Publications and subscriptions are as\nclosely connected as food purchases and meals. The point of a\npublication is for it to connect up to a subscription. In what\ncircumstances would be it be reasonable to give responsibility for\nthose objects to different and especially mutually untrusting users?\n\nSecond, in step (B), we may ask why Bob is doing this with a trigger.\nIf he's willing to create any subscription for which Alice asks, we\ncould have just given Alice the authority to do those actions herself.\nPresumably, therefore, Bob is willing to create some subscriptions for\nwhich Alice may ask and not others. Perhaps this whole arrangement is\njust a workaround for the lack of a sensible system for controlling\nwhich connection strings Alice can use, in which case what is really\nneeded here might be something like the separate connection object\nwhich Jeff postulated or my idea of a reverse pg_hba.conf. That kind\nof approach would give a better user interface to Alice, who wouldn't\nhave to rephrase all of her CREATE SUBSCRIPTION commands as insert\nstatements. Conversely, if Alice and Bob are truly dedicated to this\nconvoluted system of creating subscriptions, then Bob needs to put\nlogic into his trigger that's smart enough to block any malicious\nrequests that Alice may make. He really brought this problem on\nhimself by not doing that.\n\nThird, in step (C), it seems to me that whoever set up Alice's\npermissions has really messed up. Either the schema Bob is using for\nhis create-me-a-subscription table exists on the primary and Alice has\npermission to create tables in that schema, or else that schema does\nnot exist on the primary and Alice has permission to create it. Either\nway, that's a bad setup. Bob's table should be located in a schema for\nwhich Alice has only USAGE permissions and shouldn't have excess\npermissions on the table, either. Then this step can't happen. This\nstep could also be blocked if, instead of using a table with a\ntrigger, Bob wrote a security definer function or procedure and\ngranted EXECUTE permission on that function or procedure to Alice.\nHe's still going to need sanity checks, though, and if the function or\nprocedure inserts into a logging table or something, he'd better make\nsure that table is adequately secured rather than being, say, a table\nowned by Alice with malicious triggers on it.\n\nSo basically this doesn't really feel like a valid scenario to me.\nWe're supposed to believe that Alice is hostile to Bob, but the\nsuperuser doesn't seem to have thought very carefully about how Bob is\nsupposed to defend himself against Alice, and Bob doesn't even seem to\nbe trying. Maybe we should rename the users to Samson and Delilah? :-)\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 30 Jan 2023 12:26:31 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 30, 2023, at 9:26 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> First, it doesn't seem to make a lot of sense to have one person\n> managing the publications and someone else managing the subscriptions,\n> and especially if those parties are mutually untrusting. I can't think\n> of any real reason to set things up that way. Sure, you could, but why\n> would you? You could, equally, decide that one member of your\n> household was going to decide what's for dinner every night, and some\n> other member of your household was going to decide what gets purchased\n> at the grocery store each week. If those two people exercise their\n> responsibilities without tight coordination, or with hostile intent\n> toward each other, things are going to go badly, but that's not an\n> argument for putting a combination lock on the flour canister. It's an\n> argument for getting along better, or not having such a dumb system in\n> the first place. I don't quite see how the situation you postulate in\n> (A) and (B) is any different. Publications and subscriptions are as\n> closely connected as food purchases and meals. The point of a\n> publication is for it to connect up to a subscription.\n\nI have a grim view of the requirement that publishers and subscribers trust each other. Even when they do trust each other, they can firewall attacks by acting as if they do not.\n\n> In what\n> circumstances would be it be reasonable to give responsibility for\n> those objects to different and especially mutually untrusting users?\n\nWhen public repositories of data, such as the IANA whois database, publish their data via postgres publications.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 30 Jan 2023 10:46:07 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 30, 2023, at 9:26 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> So basically this doesn't really feel like a valid scenario to me.\n> We're supposed to believe that Alice is hostile to Bob, but the\n> superuser doesn't seem to have thought very carefully about how Bob is\n> supposed to defend himself against Alice, and Bob doesn't even seem to\n> be trying. Maybe we should rename the users to Samson and Delilah? :-)\n\nNo, Atahualpa and Pizarro.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 30 Jan 2023 11:09:26 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 30, 2023 at 1:46 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> I have a grim view of the requirement that publishers and subscribers trust each other. Even when they do trust each other, they can firewall attacks by acting as if they do not.\n\nI think it's OK if the CREATE PUBLICATION user doesn't particularly\ntrust the CREATE SUBSCRIPTION user, because the publication is just a\ngrouping of tables to which somebody can pay attention or not. The\nCREATE PUBLICATION user isn't compromised either way. But, at least as\nthings stand, I don't see how the CREATE SUBSCRIPTION user get away\nwith not trusting the CREATE PUBLICATION user. CREATE SUBSCRIPTION\nprovides no tools at all for filtering the data that the subscriber\nchooses to send.\n\nNow that can be changed, I suppose, and a run-as user would be one way\nto make progress in that direction. But I'm not sure how viable that\nis, because...\n\n> > In what\n> > circumstances would be it be reasonable to give responsibility for\n> > those objects to different and especially mutually untrusting users?\n>\n> When public repositories of data, such as the IANA whois database, publish their data via postgres publications.\n\n... for that to work, IANA would need to set up the database so that\nuntrusted parties can create logical replication slots on their\nPostgreSQL server. And I think that granting REPLICATION privilege on\nyour database to random people on the Internet is not really viable,\nnor intended to be viable. As the CREATE ROLE documentation says, \"A\nrole having the REPLICATION attribute is a very highly privileged\nrole.\"\n\nConcretely, this kind of setup would have the problem that you could\nkill the IANA database by just creating a replication slot and then\nnot using it (or replicating from it only very very slowly).\nEventually, the replication slot would either hold back xmin enough\nthat you got a lot of bloat, or cause enough WAL to be retained that\nyou ran out of disk space. Maybe you could protect yourself against\nthat kind of problem by cutting off users who get too far behind, but\nthat also cuts off people who just have an outage for longer than your\ncutoff.\n\nAlso, anyone who can connection to a replication slot can also connect\nto any other replication slot, and drop any replication slot. So if\nIANA did grant REPLICATION privilege to random people on the Internet,\none of them could jump into the system and screw things up for all the\nothers.\n\nThis kind of setup just doesn't seem viable to me.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 30 Jan 2023 14:30:27 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Jan 30, 2023, at 11:30 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> CREATE SUBSCRIPTION\n> provides no tools at all for filtering the data that the subscriber\n> chooses to send.\n> \n> Now that can be changed, I suppose, and a run-as user would be one way\n> to make progress in that direction. But I'm not sure how viable that\n> is, because...\n> \n>>> In what\n>>> circumstances would be it be reasonable to give responsibility for\n>>> those objects to different and especially mutually untrusting users?\n>> \n>> When public repositories of data, such as the IANA whois database, publish their data via postgres publications.\n> \n> ... for that to work, IANA would need to set up the database so that\n> untrusted parties can create logical replication slots on their\n> PostgreSQL server. And I think that granting REPLICATION privilege on\n> your database to random people on the Internet is not really viable,\n> nor intended to be viable.\n\nThat was an aspirational example in which there's infinite daylight between the publisher and subscriber. I, too, doubt that's ever going to be possible. But I still think we should aspire to some extra daylight between the two. Perhaps IANA doesn't publish to the whole world, but instead publishes only to subscribers who have a contract in place, and have agreed to monetary penalties should they abuse the publishing server. Whatever. There's going to be some amount of daylight possible if we design for it, and none otherwise.\n\nMy real argument here isn't against your goal of having non-superusers who can create subscriptions. That part seems fine to me.\n\nGiven that my work last year made it possible for subscriptions to run as somebody other than the subscription creator, it annoys me that you now want the subscription creator's privileges to be what the subscription runs as. That seems to undo what I worked on. In my mental model of a (superuser-creator, non-superuser-owner) pair, it seems you're logically only touching the lefthand side, so you should then have a (nonsuperuser-creator, nonsuperuser-owner) pair. But you don't. You go the apparently needless extra step of just squashing them together. I just don't see why it needs to be like that.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 30 Jan 2023 12:27:02 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Jan 27, 2023 at 5:00 PM Andres Freund <andres@anarazel.de> wrote:\n> > Or, another thought, maybe this should be checking for CREATE on the\n> > current database + also pg_create_subscription. That seems like it\n> > might be the right idea, actually.\n>\n> Yes, that seems like a good idea.\n\nDone in this version. I also changed check_conninfo to take an extra\nargument instead of returning a Boolean, as per your suggestion.\n\nI had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\nTO in terms of permissions checks. The previous version required that\nthe new owner have permissions of pg_create_subscription, but there\nseems to be no particular reason for that rule except that it happens\nto be what I made the code do. So I changed it to say that the current\nowner must have CREATE privilege on the database, and must be able to\nSET ROLE to the new owner. This matches the rule for CREATE SCHEMA.\nPossibly we should *additionally* require that the person performing\nthe rename still have pg_create_subscription, but that shouldn't be\nthe only requirement. This change means that you can't just randomly\ngive your subscription to the superuser (with or without concurrently\nattempting some other change as per your other comments) which is good\nbecause you can't do that with other object types either.\n\nThere seems to be a good deal of inconsistency here. If you want to\ngive someone a schema, YOU need CREATE on the database. But if you\nwant to give someone a table, THEY need CREATE on the containing\nschema. It make sense that we check permissions on the containing\nobject, which could be a database or a schema depending on what you're\nrenaming, but it's unclear to me why we sometimes check on the person\nperforming the ALTER command and at other times on the recipient. It's\nalso somewhat unclear to me why we are checking CREATE in the first\nplace, especially on the donor. It might make sense to have a rule\nthat you can't own an object in a place where you couldn't have\ncreated it, but there is no such rule, because you can give someone\nCREATE on a schema, they can create an object, and they you can take\nCREATE a way and they still own an object there. So it kind of looks\nto me like we made it up as we went along and that the result isn't\nvery consistent, but I'm inclined to follow CREATE SCHEMA here unless\nthere's some reason to do otherwise.\n\nAnother question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\nSUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\nsuperuser and password_required false is set. They are separate code\npaths from the rest of the ALTER SUBSCRIPTION cases, so if we want\nthat to be a rule we need dedicated code for it. I'm not quite sure\nwhat's right. There's no comparable case for ALTER USER MAPPING\nbecause a user mapping doesn't have an owner and so can't be\nreassigned to a new owner. I don't see what the harm is, especially\nfor RENAME, but I might be missing something, and it certainly seems\narguable.\n\n> > I'm not entirely clear whether there's a hazard there.\n>\n> I'm not at all either. It's just a code pattern that makes me anxious - I\n> suspect there's a few places it makes us more vulnerable.\n\nIt looks likely to me that it was cut down from the CREATE SCHEMA code, FWIW.\n\n> > If there is, I think we could fix it by moving the LockSharedObject call up\n> > higher, above object_ownercheck. The only problem with that is it lets you\n> > lock an object on which you have no permissions: see\n> > 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\n> > analogue of RangeVarGetRelidExtended.\n>\n> Yea, we really should have something like RangeVarGetRelidExtended() for other\n> kinds of objects. It'd take a fair bit of work / time to use it widely, but\n> it'll take even longer if we start in 5 years ;)\n\nWe actually have something sort of like that in the form of\nget_object_address(). It doesn't allow for a callback, but it does\nhave a retry loop.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com","msg_date":"Mon, 30 Jan 2023 15:32:34 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Jan 27, 2023 at 1:08 PM Robert Haas <robertmhaas@gmail.com> wrote:\n> > 1) Forwarding the original ambient context along with the request, so\n> > the server can check it too.\n>\n> Right, so a protocol extension. Reasonable idea, but a big lift. Not\n> only do you need everyone to be running a new enough version of\n> PostgreSQL, but existing proxies like pgpool and pgbouncer need\n> updates, too.\n\nRight.\n\n> > 2) Explicitly combining the request with the proof of authority needed\n> > to make it, as in capability-based security [3].\n>\n> As far as I can see, that link doesn't address how you'd make this\n> approach work across a network.\n\nThe CSRF-token example I gave is one. But that's HTTP-specific\n(stateless, server-driven) and probably doesn't make a lot of sense\nfor our case.\n\nFor our case, assuming that connections have side effects, one\nsolution could be for the client to signal to the server that the\nconnection should use in-band authentication only; i.e. fail the\nconnection if the credentials provided aren't good enough by\nthemselves to authenticate the client. (This has some overlap with\nSASL negotiation, maybe.)\n\nBut that still requires server support. I don't know if there's a\nclever way to tie the authentication to the request on the client side\nonly, using existing server implementations. (If connections don't\nhave side effects, require_auth should be sufficient.)\n\n> > 3) Dropping as many implicitly-held privileges as possible before making\n> > a request. This doesn't solve the problem but may considerably reduce\n> > the practical attack surface.\n>\n> Right. I definitely don't object to this kind of approach, but I don't\n> think it can ever be sufficient by itself.\n\nI agree. (But for the record, I think that an outbound proxy filter is\nalso insufficient. Someone, somewhere, is going to want to safely\nproxy through localhost _and_ have peer authentication set up.)\n\n> > I think this style focuses on absolute configuration flexibility at the\n> > expense of usability. It obfuscates the common use cases. (I have the\n> > exact same complaint about our HBA and ident configs, so I may be\n> > fighting uphill.)\n>\n> That's probably somewhat true, but on the other hand, it also is more\n> powerful than what you're describing. In your system, is there some\n> way the DBA can say \"hey, you can connect to any of the machines on\n> this list of subnets, but nothing else\"? Or equally, \"hey, you may NOT\n> connect to any machine on this list of subnets, but anything else is\n> fine\"? Or \"you can connect to these subnets without SSL, but if you\n> want to talk to anything else, you need to use SSL\"?\n\nI guess I didn't call it out explicitly, so it was fair to assume that\nit did not. I don't think we should ignore those cases.\n\nBut if we let the configuration focus on policies instead, and\nsimultaneously improve the confused-deputy problem, then any IP/host\nfilter functionality that we provide becomes an additional safety\nmeasure instead of your only viable line of defense. \"I screwed up our\nIP filter, but we're still safe because the proxy refused to forward\nits client cert to the backend.\" Or, \"this other local application\nrequires peer authentication, but it's okay because the proxy\ndisallows those connections by default.\"\n\n> Your idea\n> seems to rely on us being able to identify all of the policies that a\n> user is likely to want and give names to each one, and I don't feel\n> very confident that that's realistic. But maybe I'm misinterpreting\n> your idea?\n\nNo, that's pretty accurate. But I'm used to systems that provide a\nridiculous number of policies [1, 2] via what's basically a scoped\nproperty bag. \"Turn off option 1 and 2 globally. For host A and IP\naddress B, turn on option 1 as an exception.\" And I don't really\nexpect us to need as many options as those systems do.\n\nI think that configuration style evolves well, it focuses on the right\nthings, and it can still handle IP lists intuitively [3], if that's\nthe way a DBA really wants to set up policies.\n\n--Jacob\n\n[1] https://httpd.apache.org/docs/2.4/mod/mod_proxy.html\n[2] https://www.haproxy.com/documentation/hapee/latest/onepage/#4\n[3] https://docs.nginx.com/nginx/admin-guide/security-controls/controlling-access-proxied-tcp/\n\n\n","msg_date":"Mon, 30 Jan 2023 13:12:31 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Mon, Jan 30, 2023 at 3:27 PM Mark Dilger\n<mark.dilger@enterprisedb.com> wrote:\n> That was an aspirational example in which there's infinite daylight between the publisher and subscriber. I, too, doubt that's ever going to be possible. But I still think we should aspire to some extra daylight between the two. Perhaps IANA doesn't publish to the whole world, but instead publishes only to subscribers who have a contract in place, and have agreed to monetary penalties should they abuse the publishing server. Whatever. There's going to be some amount of daylight possible if we design for it, and none otherwise.\n>\n> My real argument here isn't against your goal of having non-superusers who can create subscriptions. That part seems fine to me.\n>\n> Given that my work last year made it possible for subscriptions to run as somebody other than the subscription creator, it annoys me that you now want the subscription creator's privileges to be what the subscription runs as. That seems to undo what I worked on. In my mental model of a (superuser-creator, non-superuser-owner) pair, it seems you're logically only touching the lefthand side, so you should then have a (nonsuperuser-creator, nonsuperuser-owner) pair. But you don't. You go the apparently needless extra step of just squashing them together. I just don't see why it needs to be like that.\n\nI feel like you're accusing me of removing functionality that has\nnever existed. A subscription doesn't run as the subscription creator.\nIt runs as the subscription owner. If you or anyone else had added the\ncapability for it to run as someone other than the subscription owner,\nI certainly wouldn't be trying to back that capability out as part of\nthis patch, and because there isn't, I'm not proposing to add that as\npart of this patch. I don't see how that makes me guilty of squashing\nanything together. The current state of affairs, where the run-as user\nis taken from pg_subscription.subowner, the same field that is updated\nby ALTER SUBSCRIPTION ... OWNER TO, is the result of your work, not\nanything that I have done or am proposing to do.\n\nI also *emphatically* disagree with the idea that this undoes what you\nworked on. My patch would be *impossible* without your work. Prior to\nyour work, the run-as user was always, basically, the superuser, and\nso the idea of allowing anyone other than a superuser to execute\nCREATE SUBSCRIPTION would be flat-out nuts. Because of your work,\nthat's now a thing that we may be able to reasonably allow, if we can\nwork through the remaining issues. So I'm grateful to you, and also\nsorry to hear that you're annoyed with me. But I still don't think\nthat the fact that the division you want doesn't exist is somehow my\nfault.\n\nI'm kind of curious why you *didn't* make this distinction at the time\nthat you were did the other work in this area. Maybe my memory is\nplaying tricks on me again, but I seem to recall talking about the\nidea with you at the time, and I seem to recall thinking that it\nsounded like an OK idea. I seem to vaguely recall us discussing\nhazards like: well, what if replication causes code to get executed as\nthe subscription owner that that causes something bad to happen? But I\nthink the only way that happens is if they put triggers on the tables\nthat are being replicated, which is their choice, and they can avoid\ninstalling problematic code there if they want. I think there might\nhave been some other scenarios, too, but I just can't remember. In any\ncase, I don't think the idea is completely without merit. I think it\ncould very well be something that we want to have for one reason or\nanother. But I don't currently understand exactly what those reasons\nare, and I don't see any reason why one patch should both split owner\nfrom run-as user and also allow the owner to be a non-superuser. That\nseems like two different efforts to me.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 30 Jan 2023 16:29:06 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 30, 2023 at 4:12 PM Jacob Champion <jchampion@timescale.com> wrote:\n> For our case, assuming that connections have side effects, one\n> solution could be for the client to signal to the server that the\n> connection should use in-band authentication only; i.e. fail the\n> connection if the credentials provided aren't good enough by\n> themselves to authenticate the client. (This has some overlap with\n> SASL negotiation, maybe.)\n\nI'm not an expert on this stuff, but to me that feels like a weak and\nfuzzy concept. If the client is going to tell the server something,\nI'd much rather have it say something like \"i'm proxying a request\nfrom my local user rhaas, who authenticated using such and such a\nmethod and connected from such and such an IP yadda yadda\". That feels\nto me like really clear communication that the server can then be\nconfigured to something about via pg_hba.conf or similar. Saying \"use\nin-band authentication only\", to me, feels much murkier. As the\nrecipient of that message, I don't know exactly what to do about it,\nand it feels like whatever heuristic I adopt might end up being wrong\nand something bad happens anyway.\n\n> I agree. (But for the record, I think that an outbound proxy filter is\n> also insufficient. Someone, somewhere, is going to want to safely\n> proxy through localhost _and_ have peer authentication set up.)\n\nWell then they're indeed going to need some way to distinguish a\nproxied connection from a non-proxied one. You can't send identical\nconnection requests in different scenarios and get different\nresults....\n\n> I guess I didn't call it out explicitly, so it was fair to assume that\n> it did not. I don't think we should ignore those cases.\n\nOK, cool.\n\n> But if we let the configuration focus on policies instead, and\n> simultaneously improve the confused-deputy problem, then any IP/host\n> filter functionality that we provide becomes an additional safety\n> measure instead of your only viable line of defense. \"I screwed up our\n> IP filter, but we're still safe because the proxy refused to forward\n> its client cert to the backend.\" Or, \"this other local application\n> requires peer authentication, but it's okay because the proxy\n> disallows those connections by default.\"\n\nDefense in depth is good.\n\n> > Your idea\n> > seems to rely on us being able to identify all of the policies that a\n> > user is likely to want and give names to each one, and I don't feel\n> > very confident that that's realistic. But maybe I'm misinterpreting\n> > your idea?\n>\n> No, that's pretty accurate. But I'm used to systems that provide a\n> ridiculous number of policies [1, 2] via what's basically a scoped\n> property bag. \"Turn off option 1 and 2 globally. For host A and IP\n> address B, turn on option 1 as an exception.\" And I don't really\n> expect us to need as many options as those systems do.\n>\n> I think that configuration style evolves well, it focuses on the right\n> things, and it can still handle IP lists intuitively [3], if that's\n> the way a DBA really wants to set up policies.\n\nI think what we really need here is an example or three of a proposed\nconfiguration file syntax. I think it would be good if we could pick a\nsyntax that doesn't require a super-complicated parser, and that maybe\nhas something in common with our existing configuration file syntaxes.\nBut if we have to invent something new, then we can do that.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 30 Jan 2023 17:21:22 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"\n\n> On Jan 30, 2023, at 1:29 PM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> I feel like you're accusing me of removing functionality that has\n> never existed. A subscription doesn't run as the subscription creator.\n> It runs as the subscription owner. If you or anyone else had added the\n> capability for it to run as someone other than the subscription owner,\n> I certainly wouldn't be trying to back that capability out as part of\n> this patch, and because there isn't, I'm not proposing to add that as\n> part of this patch. I don't see how that makes me guilty of squashing\n> anything together. The current state of affairs, where the run-as user\n> is taken from pg_subscription.subowner, the same field that is updated\n> by ALTER SUBSCRIPTION ... OWNER TO, is the result of your work, not\n> anything that I have done or am proposing to do.\n> \n> I also *emphatically* disagree with the idea that this undoes what you\n> worked on. My patch would be *impossible* without your work. Prior to\n> your work, the run-as user was always, basically, the superuser, and\n> so the idea of allowing anyone other than a superuser to execute\n> CREATE SUBSCRIPTION would be flat-out nuts. Because of your work,\n> that's now a thing that we may be able to reasonably allow, if we can\n> work through the remaining issues. So I'm grateful to you, and also\n> sorry to hear that you're annoyed with me. But I still don't think\n> that the fact that the division you want doesn't exist is somehow my\n> fault.\n> \n> I'm kind of curious why you *didn't* make this distinction at the time\n> that you were did the other work in this area. Maybe my memory is\n> playing tricks on me again, but I seem to recall talking about the\n> idea with you at the time, and I seem to recall thinking that it\n> sounded like an OK idea. I seem to vaguely recall us discussing\n> hazards like: well, what if replication causes code to get executed as\n> the subscription owner that that causes something bad to happen? But I\n> think the only way that happens is if they put triggers on the tables\n> that are being replicated, which is their choice, and they can avoid\n> installing problematic code there if they want. I think there might\n> have been some other scenarios, too, but I just can't remember. In any\n> case, I don't think the idea is completely without merit. I think it\n> could very well be something that we want to have for one reason or\n> another. But I don't currently understand exactly what those reasons\n> are, and I don't see any reason why one patch should both split owner\n> from run-as user and also allow the owner to be a non-superuser. That\n> seems like two different efforts to me.\n\nI don't have a concrete problem with your patch, and wouldn't object if you committed it. My concerns were more how you were phrasing things, but it seems not worth any additional conversation, because it's probably a distinction without a difference.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 31 Jan 2023 03:32:38 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-30 10:44:29 -0500, Robert Haas wrote:\n> On a technical level, I think that the idea of having a separate\n> objection for the connection string vs. the subscription itself is\n> perfectly sound, and to repeat what I said earlier, if someone wants\n> to implement that, cool. I also agree that it has the advantage that\n> you specify, namely, that someone can have rights to modify one of\n> those objects but not the other. What that lets you do is define a\n> short list of known systems and say, hey, you can replicate whatever\n> tables you want with whatever options you want, but only between these\n> systems. I'm not quite sure what problem that solves, though.\n\nThat does seem somewhat useful, but also fairly limited, at least as\nlong as it's really just a single connection, rather than a \"pattern\" of\nsafe connections.\n\n\n> Unfortunately, I have even less of an idea about what the run-as\n> concept is supposed to accomplish. I mean, at one level, I see it\n> quite clearly: the user creating the subscription wants replication to\n> have restricted privileges when it's running, and so they make the\n> run-as user some role with fewer privileges than their own. Brilliant.\n> But then I get stuck: against what kind of attack does that actually\n> protect us? If I'm a high privilege user, perhaps even a superuser,\n> and it's not safe to have logical replication running as me, then it\n> seems like the security model of logical replication is fundamentally\n> busted and we need to fix that.\n\nI don't really understand that - the run-as approach seems like a\nnecessary piece of improving the security model.\n\nI think it's perfectly reasonable to want to replicate from one system\nin another, but to not want to allow logical replication to insert into\npg_class or whatnot. So not using superuser to execute the replication\nmakes sense.\n\nThis is particularly the case if you're just replicating a small part of\nthe tables from one system to another. E.g. in a sharded setup, you may\nwant to replicate metadata too servers.\n\nEven if all the systems are operated by people you trust (including\npossibly even yourself, if you want to go that far), you may want to\nreduce the blast radius of privilege escalation, or even just bugs, to a\nsmaller amount of data.\n\n\nI think we'll need two things to improve upon the current situation:\n\n1) run-as user, to reduce the scope of potential danger\n\n2) Option to run the database inserts as the owner of the table, with a\n check that the run-as is actually allowed to perform work as the\n owning role. That prevents escalation from table owner (who could add\n default expressions etc) from gettng the privs of the\n run-as/replication owner.\n\n\nI think it makes sense for 1) to be a fairly privileged user, but I\nthink it's good practice for that user to not be allowed to change the\nsystem configuration etc.\n\n\n> It can't be right to say that if you have 263 users in a database and\n> you want to replicate the whole database to some other node, you need\n> 263 different subscriptions with a different run-as user for each. You\n> need to be able to run all of that logical replication as the\n> superuser or some other high-privilege user and not end up with a\n> security compromise.\n\nI'm not quite following along here - are you thinking of 263 tables\nowned by 263 users? If yes, that's why I am thinking that we need the\noption to perform each table modification as the owner of that table\n(with the same security restrictions we use for REINDEX etc).\n\n\n> And if we suppose that that already works and is safe, well then\n> what's the case where I do need a run-as user?\n\nIt's not at all safe today, IMO. You need to trust that nothing bad will\nbe replicated, otherwise the owner of the subscription has to be\nconsidered compromised.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 31 Jan 2023 16:01:16 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Jan 31, 2023 at 7:01 PM Andres Freund <andres@anarazel.de> wrote:\n> I don't really understand that - the run-as approach seems like a\n> necessary piece of improving the security model.\n>\n> I think it's perfectly reasonable to want to replicate from one system\n> in another, but to not want to allow logical replication to insert into\n> pg_class or whatnot. So not using superuser to execute the replication\n> makes sense.\n>\n> This is particularly the case if you're just replicating a small part of\n> the tables from one system to another. E.g. in a sharded setup, you may\n> want to replicate metadata too servers.\n\nI don't think that a system catalog should be considered a valid\nreplication target, no matter who owns the subscription, so ISTM that\nwriting to pg_class should be blocked regardless. The thing I'm\nstruggling to understand is: if you only want to replicate into tables\nthat Alice can write, why not just make Alice own the subscription?\nFor a run-as user to make sense, you need a scenario where we want the\nreplication to target only tables that Alice can touch, but we also\ndon't want Alice herself to be able to touch the subscription, so you\nmake Alice the run-as user and yourself the owner, or something like\nthat. But I'm not sure what that scenario is exactly.\n\nMark was postulating a scenario where the publisher and subscriber\ndon't trust each other. I was thinking a little bit more about that. I\nstill maintain that the current system is poorly set up to make that\nwork, but suppose we wanted to do better. We could add filtering on\nthe subscriber side, like you list schemas or specific relations that\nyou are or are not willing to replicate into. Then you could, for\nexample, connect your subscription to a certain remote publication,\nbut with the restriction that you're only willing to replicate into\nthe \"headquarters\" schema. Then we'll replicate whatever tables they\nsend us, but if the dorks at headquarters mess up the publications on\ntheir end (intentionally or otherwise) and add some tables from the\n\"locally_controlled_stuff\" schema, we'll refuse to replicate that into\nour eponymous schema. I don't think this kind of system is well-suited\nto environments where people are totally hostile to each other,\nbecause you still need to have replication slots on the remote side\nand stuff. Also, having the remote side decode stuff and ignoring it\nlocally is expensive, and I bet if we add stuff like this then people\nwill misuse it and be sad. But it would make the system easier to\nreason about: I know for sure that this subscription will only write\nto these places, because that's all I've given it permission to do.\n\nIn the sharding scenario you mention, if you want to provide\naccidental writes to unrelated tables due to the publication being not\nwhat we expect, you can either make the subscription owned by the same\nrole that owns the sharded tables, or a special-purpose role that has\npermission to write to exactly the set of tables that you expect to be\ntouched and no others. Or, if you had something like what I posited in\nthe last paragraph, you could use that instead. But I don't see how a\nseparate run-as user helps. If I'm just being super-dense here, I hope\nthat one of you will explain using short words. :-)\n\n> I think we'll need two things to improve upon the current situation:\n>\n> 1) run-as user, to reduce the scope of potential danger\n>\n> 2) Option to run the database inserts as the owner of the table, with a\n> check that the run-as is actually allowed to perform work as the\n> owning role. That prevents escalation from table owner (who could add\n> default expressions etc) from gettng the privs of the\n> run-as/replication owner.\n\nI'm not quite sure what we do here now, but I agree that trigger\nfiring seems like a problem. It might be that we need to worry about\nthe user on the origin server, too. If Alice inserts a row that causes\na replicated table owned by Bob to fire a trigger or evaluate a\ndefault expression or whatever due the presence of a subscription\nowned by Charlie, there is a risk that Alice might try to attack\neither Bob or Charlie, or that Bob might try to attack Charlie.\n\n> > And if we suppose that that already works and is safe, well then\n> > what's the case where I do need a run-as user?\n>\n> It's not at all safe today, IMO. You need to trust that nothing bad will\n> be replicated, otherwise the owner of the subscription has to be\n> considered compromised.\n\nWhat kinds of things are bad to replicate?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 1 Feb 2023 09:43:39 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Feb 1, 2023, at 6:43 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n\n> The thing I'm\n> struggling to understand is: if you only want to replicate into tables\n> that Alice can write, why not just make Alice own the subscription?\n> For a run-as user to make sense, you need a scenario where we want the\n> replication to target only tables that Alice can touch, but we also\n> don't want Alice herself to be able to touch the subscription, so you\n> make Alice the run-as user and yourself the owner, or something like\n> that. But I'm not sure what that scenario is exactly.\n\nThis \"run-as\" idea came about because we didn't want arbitrary roles to be able to change the subscription's connection string. A competing idea was to have a server object rather than a string, with roles like Alice being able to use the server object if they have been granted usage privilege, and not otherwise. So the \"run-as\" and \"server\" ideas were somewhat competing.\n\n> Mark was postulating a scenario where the publisher and subscriber\n> don't trust each other. I was thinking a little bit more about that. I\n> still maintain that the current system is poorly set up to make that\n> work, but suppose we wanted to do better. We could add filtering on\n> the subscriber side, like you list schemas or specific relations that\n> you are or are not willing to replicate into. Then you could, for\n> example, connect your subscription to a certain remote publication,\n> but with the restriction that you're only willing to replicate into\n> the \"headquarters\" schema. Then we'll replicate whatever tables they\n> send us, but if the dorks at headquarters mess up the publications on\n> their end (intentionally or otherwise) and add some tables from the\n> \"locally_controlled_stuff\" schema, we'll refuse to replicate that into\n> our eponymous schema.\n\nThat example is good, though I don't see how \"filters\" are better than roles+privileges. Care to elaborate?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 1 Feb 2023 09:22:31 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Jan 30, 2023 at 2:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\n> On Mon, Jan 30, 2023 at 4:12 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > For our case, assuming that connections have side effects, one\n> > solution could be for the client to signal to the server that the\n> > connection should use in-band authentication only; i.e. fail the\n> > connection if the credentials provided aren't good enough by\n> > themselves to authenticate the client. (This has some overlap with\n> > SASL negotiation, maybe.)\n>\n> I'm not an expert on this stuff, but to me that feels like a weak and\n> fuzzy concept. If the client is going to tell the server something,\n> I'd much rather have it say something like \"i'm proxying a request\n> from my local user rhaas, who authenticated using such and such a\n> method and connected from such and such an IP yadda yadda\". That feels\n> to me like really clear communication that the server can then be\n> configured to something about via pg_hba.conf or similar. Saying \"use\n> in-band authentication only\", to me, feels much murkier. As the\n> recipient of that message, I don't know exactly what to do about it,\n> and it feels like whatever heuristic I adopt might end up being wrong\n> and something bad happens anyway.\n\nIs it maybe just a matter of terminology? If a proxy tells the server,\n\"This user is logging in. Here's the password I have for them. DO NOT\nauthenticate using anything else,\" and the HBA says to use ident auth\nfor that user, then the server fails the connection. That's what I\nmean by in-band -- the proxy says, \"here are the credentials for this\nconnection.\" That's it.\n\nAlternatively, if you really don't like making this server-side: any\nfuture \"connection side effects\" we add, such as logon triggers, could\neither be opted into by the client or explicitly invoked by the client\nafter it's happy with the authentication exchange. Or it could be\ndisabled at the server side for forms of ambient authn. (This is\ngetting closer to HTTP's method safety concept.)\n\n> > I agree. (But for the record, I think that an outbound proxy filter is\n> > also insufficient. Someone, somewhere, is going to want to safely\n> > proxy through localhost _and_ have peer authentication set up.)\n>\n> Well then they're indeed going to need some way to distinguish a\n> proxied connection from a non-proxied one. You can't send identical\n> connection requests in different scenarios and get different\n> results....\n\nYeah. Most of these solutions require explicitly labelling things that\nwere implicit before.\n\n> I think what we really need here is an example or three of a proposed\n> configuration file syntax. I think it would be good if we could pick a\n> syntax that doesn't require a super-complicated parser\n\nAgreed. The danger from my end is, I'm trained on configuration\nformats that have infinite bells and whistles. I don't really want to\ngo too crazy with it.\n\n> and that maybe\n> has something in common with our existing configuration file syntaxes.\n> But if we have to invent something new, then we can do that.\n\nOkay. Personally I'd like\n- the ability to set options globally (so filters are optional)\n- the ability to maintain many options for a specific scope (host? IP\nrange?) without making my config lines grow without bound\n- the ability to audit a configuration without trusting its comments\n\nBut getting all of my wishlist into a sane configuration format that\nhandles all the use cases is the tricky part. I'll think about it.\n\n--Jacob\n\n\n","msg_date":"Wed, 1 Feb 2023 12:37:26 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"Hi,\n\nOn 2023-02-01 09:43:39 -0500, Robert Haas wrote:\n> On Tue, Jan 31, 2023 at 7:01 PM Andres Freund <andres@anarazel.de> wrote:\n> > I don't really understand that - the run-as approach seems like a\n> > necessary piece of improving the security model.\n> >\n> > I think it's perfectly reasonable to want to replicate from one system\n> > in another, but to not want to allow logical replication to insert into\n> > pg_class or whatnot. So not using superuser to execute the replication\n> > makes sense.\n> >\n> > This is particularly the case if you're just replicating a small part of\n> > the tables from one system to another. E.g. in a sharded setup, you may\n> > want to replicate metadata too servers.\n> \n> I don't think that a system catalog should be considered a valid\n> replication target, no matter who owns the subscription, so ISTM that\n> writing to pg_class should be blocked regardless.\n\nThe general point is that IMO is that in many setups you should use a\nuser with fewer privileges than a superuser. It doesn't really matter\nwhether we have an ad-hoc restriction for system catalogs. More often\nthan not being able to modify other tables will give you a lot of\nprivileges too.\n\n\n> The thing I'm struggling to understand is: if you only want to\n> replicate into tables that Alice can write, why not just make Alice\n> own the subscription?\n\nBecause it implies that the replication happens as a user that's\nprivileged enough to change the configuration of replication.\n\n\n> Mark was postulating a scenario where the publisher and subscriber\n> don't trust each other.\n\nFWIW, I don't this this is mainly about \"trust\", but instead about\nlayering security / the principle of least privilege. The \"run-as\" user\n(i.e. currently owner) is constantly performing work on behalf of a\nremote node, including executing code (default clauses etc). To make it\nharder to use such a cross-system connection to move from one system to\nthe next, it's a good idea to execute it in the least privileged context\npossible. And I don't see why it'd need the permission to modify the\ndefinition of the subscription and similar \"admin\" tasks.\n\nIt's not that such an extra layer would necessarily completely stop an\nattacker. But it might delay them and make their attack more noisy.\n\n\nSimilarly, if I were to operate an important production environment\nagain, I'd not have relations owned by the [pseudo]superuser, but by a\nuser controlled by the [pseudo]superuser. That way somebody tricking the\nsuperuser into a REINDEX or such only gets the ability to execute code\nin a less privileged context.\n\n\n\n\n> I was thinking a little bit more about that. I\n> still maintain that the current system is poorly set up to make that\n> work, but suppose we wanted to do better. We could add filtering on\n> the subscriber side, like you list schemas or specific relations that\n> you are or are not willing to replicate into.\n\nIsn't that largely a duplication of the ACLs on relations etc?\n\n\n> > I think we'll need two things to improve upon the current situation:\n> >\n> > 1) run-as user, to reduce the scope of potential danger\n> >\n> > 2) Option to run the database inserts as the owner of the table, with a\n> > check that the run-as is actually allowed to perform work as the\n> > owning role. That prevents escalation from table owner (who could add\n> > default expressions etc) from gettng the privs of the\n> > run-as/replication owner.\n> \n> I'm not quite sure what we do here now, but I agree that trigger\n> firing seems like a problem. It might be that we need to worry about\n> the user on the origin server, too. If Alice inserts a row that causes\n> a replicated table owned by Bob to fire a trigger or evaluate a\n> default expression or whatever due the presence of a subscription\n> owned by Charlie, there is a risk that Alice might try to attack\n> either Bob or Charlie, or that Bob might try to attack Charlie.\n\nThe attack on Bob exists without logical replication too - a REINDEX or\nsuch is executed as the owner of the relation and re-evaluates index\nexpressions, constraints etc. Given our security model I don't think we\ncan protect the relation owner if they trust somebody to insert rows, so\nI don't really know what we can do to protect Charlie against Bob.\n\n\n\n> > > And if we suppose that that already works and is safe, well then\n> > > what's the case where I do need a run-as user?\n> >\n> > It's not at all safe today, IMO. You need to trust that nothing bad will\n> > be replicated, otherwise the owner of the subscription has to be\n> > considered compromised.\n> \n> What kinds of things are bad to replicate?\n\nI think that's unfortunately going to be specific to a setup.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 1 Feb 2023 12:37:28 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-01-30 15:32:34 -0500, Robert Haas wrote:\n> I had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\n> TO in terms of permissions checks. The previous version required that\n> the new owner have permissions of pg_create_subscription, but there\n> seems to be no particular reason for that rule except that it happens\n> to be what I made the code do. So I changed it to say that the current\n> owner must have CREATE privilege on the database, and must be able to\n> SET ROLE to the new owner. This matches the rule for CREATE SCHEMA.\n> Possibly we should *additionally* require that the person performing\n> the rename still have pg_create_subscription, but that shouldn't be\n> the only requirement.\n\nAs long as owner and run-as are the same, I think it's strongly\npreferrable to *not* require pg_create_subscription.\n\n\n> There seems to be a good deal of inconsistency here. If you want to\n> give someone a schema, YOU need CREATE on the database. But if you\n> want to give someone a table, THEY need CREATE on the containing\n> schema. It make sense that we check permissions on the containing\n> object, which could be a database or a schema depending on what you're\n> renaming, but it's unclear to me why we sometimes check on the person\n> performing the ALTER command and at other times on the recipient. It's\n> also somewhat unclear to me why we are checking CREATE in the first\n> place, especially on the donor. It might make sense to have a rule\n> that you can't own an object in a place where you couldn't have\n> created it, but there is no such rule, because you can give someone\n> CREATE on a schema, they can create an object, and they you can take\n> CREATE a way and they still own an object there. So it kind of looks\n> to me like we made it up as we went along and that the result isn't\n> very consistent, but I'm inclined to follow CREATE SCHEMA here unless\n> there's some reason to do otherwise.\n\nYuck. No idea what the best policy around this is.\n\n\n> Another question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\n> SUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\n> superuser and password_required false is set.\n\nI don't really see a benefit in allowing it, so I'm inclined to go for\nthe more restrictive option. But this is a really weakly held opinion.\n\n\n\n> > > If there is, I think we could fix it by moving the LockSharedObject call up\n> > > higher, above object_ownercheck. The only problem with that is it lets you\n> > > lock an object on which you have no permissions: see\n> > > 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\n> > > analogue of RangeVarGetRelidExtended.\n> >\n> > Yea, we really should have something like RangeVarGetRelidExtended() for other\n> > kinds of objects. It'd take a fair bit of work / time to use it widely, but\n> > it'll take even longer if we start in 5 years ;)\n>\n> We actually have something sort of like that in the form of\n> get_object_address(). It doesn't allow for a callback, but it does\n> have a retry loop.\n\nHm, sure looks like that code doesn't do any privilege checking...\n\n\n> @@ -1269,13 +1270,19 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)\n> \t\t\t\t\t\t\t\t\tslotname,\n> \t\t\t\t\t\t\t\t\tNAMEDATALEN);\n>\n> +\t/* Is the use of a password mandatory? */\n> +\tmust_use_password = MySubscription->passwordrequired &&\n> +\t\t!superuser_arg(MySubscription->owner);\n\nThere's a few repetitions of this - perhaps worth putting into a helper?\n\n\n> @@ -180,6 +181,13 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,\n> if (PQstatus(conn->streamConn) != CONNECTION_OK)\n> goto bad_connection_errmsg;\n>\n> + if (must_use_password && !PQconnectionUsedPassword(conn->streamConn))\n> + ereport(ERROR,\n> + (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),\n> + errmsg(\"password is required\"),\n> + errdetail(\"Non-superuser cannot connect if the server does not request a password.\"),\n> + errhint(\"Target server's authentication method must be changed. or set password_required=false in the subscription attributes\\\n.\")));\n> +\n> if (logical)\n> {\n> PGresult *res;\n\nThis still leaks the connection on error, no?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 1 Feb 2023 13:02:29 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Feb 1, 2023 at 1:09 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\n> > On Feb 1, 2023, at 6:43 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> > The thing I'm\n> > struggling to understand is: if you only want to replicate into tables\n> > that Alice can write, why not just make Alice own the subscription?\n> > For a run-as user to make sense, you need a scenario where we want the\n> > replication to target only tables that Alice can touch, but we also\n> > don't want Alice herself to be able to touch the subscription, so you\n> > make Alice the run-as user and yourself the owner, or something like\n> > that. But I'm not sure what that scenario is exactly.\n>\n> This \"run-as\" idea came about because we didn't want arbitrary roles to be able to change the subscription's connection string. A competing idea was to have a server object rather than a string, with roles like Alice being able to use the server object if they have been granted usage privilege, and not otherwise. So the \"run-as\" and \"server\" ideas were somewhat competing.\n\nAs far as not changing the connection string goes, a few more ideas\nhave entered the fray: the current patch uses a password_required\nproperty that is modelled on postgres_fdw, and I've elsewhere proposed\na reverse pg_hba.conf.\n\nIMHO, for the use cases that I can imagine, the reverse pg_hba.conf\nidea feels better than all competitors, because it's the only idea\nthat lets you define a class of acceptable connection strings. Jeff's\nidea of a separate connection object is fine if you have a specific,\nshort list of connection strings and you want to allow those and\ndisallow everything else, and there may be cases where people want\nthat, and that's fine, but my guess is that it's overly restrictive in\na lot of environments. The password_required property has the virtue\nof being compatible with what we do in other places right now, and of\npreventing wraparound-to-superuser attacks effectively, but it's\ntotally unconfigurable and that sucks. The runas user idea gives you\nsome control over who is allowed to set the connection string, but it\ndoesn't help you delegate that to a non-superuser, because the idea\nthere is that you want the non-superuser to be able to set connection\nstrings that are OK with the actual superuser but not others.\n\nI think part of my confusion here is that I thought that the point of\nthe runas user was to defend against logical replication itself\nchanging the connection string, and I don't see how it would do that.\nIt's just moving rows around. If the point is that somebody who can\nlog in as the runas user might change the connection string to\nsomething we don't like, that makes somewhat more sense. I think I had\nin my head that you wouldn't use someone's actual login role to run\nlogical replication, but rather some role specifically set up for that\npurpose. In that scenario, nobody's running SQL commands as the runas\nuser, so even if they also own the subscription, there's no way for it\nto get modified.\n\n> > Mark was postulating a scenario where the publisher and subscriber\n> > don't trust each other. I was thinking a little bit more about that. I\n> > still maintain that the current system is poorly set up to make that\n> > work, but suppose we wanted to do better. We could add filtering on\n> > the subscriber side, like you list schemas or specific relations that\n> > you are or are not willing to replicate into. Then you could, for\n> > example, connect your subscription to a certain remote publication,\n> > but with the restriction that you're only willing to replicate into\n> > the \"headquarters\" schema. Then we'll replicate whatever tables they\n> > send us, but if the dorks at headquarters mess up the publications on\n> > their end (intentionally or otherwise) and add some tables from the\n> > \"locally_controlled_stuff\" schema, we'll refuse to replicate that into\n> > our eponymous schema.\n>\n> That example is good, though I don't see how \"filters\" are better than roles+privileges. Care to elaborate?\n\nI'm not sure that they are. Are we assuming that the user who is\ncreating subscriptions is also powerful enough to create roles and\ngive them just the required amount of privilege? If so, it seems like\nthey might as well just do it that way. And maybe we should assume\nthat, because in most cases, a dedication replication role makes more\nsense to me than running replication under some role that you're also\nusing for other things. On the other hand, I bet a lot of people today\nare just running replication as a superuser, in which case maybe this\ncould be useful? This whole idea was mostly just me spitballing to see\nwhat other people thought. I'm not wild about the complexity involved\nfor what you get out of it, so if we don't need it, that's more than\nfine with me.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 2 Feb 2023 09:11:17 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Feb 1, 2023 at 3:37 PM Andres Freund <andres@anarazel.de> wrote:\n> The general point is that IMO is that in many setups you should use a\n> user with fewer privileges than a superuser. It doesn't really matter\n> whether we have an ad-hoc restriction for system catalogs. More often\n> than not being able to modify other tables will give you a lot of\n> privileges too.\n\nI don't know what you mean by this. DML doesn't confer privileges. If\ncode gets executed and runs with the replication user's credentials,\nthat could lead to privilege escalation, but just moving rows around\ndoesn't, at least not in the database sense. It might confer\nunanticipated real-world benefits, like if you can update your own\nsalary or something, but in the context of replication you have to\nhave had the ability to do that on some other node anyway. If that\nchange wasn't supposed to get replicated to the local node, then why\nare we using replication? Or why is that table in the publication? I'm\nconfused.\n\n> > The thing I'm struggling to understand is: if you only want to\n> > replicate into tables that Alice can write, why not just make Alice\n> > own the subscription?\n>\n> Because it implies that the replication happens as a user that's\n> privileged enough to change the configuration of replication.\n\nBut again, replication is just about inserting, updating, and deleting\nrows. To change the replication configuration, you have to be able to\nparlay that into the ability to execute code. That's why I think\ntrigger security is really important. But I'm wondering if there's\nsome way we can handle that that doesn't require us to make a decision\nabout arun-as user. For instance, if firing triggers as the table\nowner is an acceptable solution, then the only thing that the run-as\nuser is actually controlling is which tables we're willing to\nreplicate into in the first place (unless there's some other way that\nlogical replication can run arbitrary code). The name almost becomes a\nmisnomer in that case. It's not a run-as user, it's\nuse-this-user's-permissions-to-see-if-I-should-fail-replication user.\n\n> > I was thinking a little bit more about that. I\n> > still maintain that the current system is poorly set up to make that\n> > work, but suppose we wanted to do better. We could add filtering on\n> > the subscriber side, like you list schemas or specific relations that\n> > you are or are not willing to replicate into.\n>\n> Isn't that largely a duplication of the ACLs on relations etc?\n\nYeah, maybe.\n\n> > I'm not quite sure what we do here now, but I agree that trigger\n> > firing seems like a problem. It might be that we need to worry about\n> > the user on the origin server, too. If Alice inserts a row that causes\n> > a replicated table owned by Bob to fire a trigger or evaluate a\n> > default expression or whatever due the presence of a subscription\n> > owned by Charlie, there is a risk that Alice might try to attack\n> > either Bob or Charlie, or that Bob might try to attack Charlie.\n>\n> The attack on Bob exists without logical replication too - a REINDEX or\n> such is executed as the owner of the relation and re-evaluates index\n> expressions, constraints etc. Given our security model I don't think we\n> can protect the relation owner if they trust somebody to insert rows, so\n> I don't really know what we can do to protect Charlie against Bob.\n\nYikes.\n\n> > > > And if we suppose that that already works and is safe, well then\n> > > > what's the case where I do need a run-as user?\n> > >\n> > > It's not at all safe today, IMO. You need to trust that nothing bad will\n> > > be replicated, otherwise the owner of the subscription has to be\n> > > considered compromised.\n> >\n> > What kinds of things are bad to replicate?\n>\n> I think that's unfortunately going to be specific to a setup.\n\nCan you give an example?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 2 Feb 2023 09:28:03 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-02-02 09:28:03 -0500, Robert Haas wrote:\n> I don't know what you mean by this. DML doesn't confer privileges. If\n> code gets executed and runs with the replication user's credentials,\n> that could lead to privilege escalation, but just moving rows around\n> doesn't, at least not in the database sense.\n\nExecuting DML ends up executing code. Think predicated/expression\nindexes, triggers, default expressions etc. If a badly written trigger\netc can be tricked to do arbitrary code exec, an attack will be able to\nrun with the privs of the run-as user. How bad that is is influenced to\nsome degree by the amount of privileges that user has.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Fri, 3 Feb 2023 00:47:48 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Feb 1, 2023 at 3:37 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > I'm not an expert on this stuff, but to me that feels like a weak and\n> > fuzzy concept. If the client is going to tell the server something,\n> > I'd much rather have it say something like \"i'm proxying a request\n> > from my local user rhaas, who authenticated using such and such a\n> > method and connected from such and such an IP yadda yadda\". That feels\n> > to me like really clear communication that the server can then be\n> > configured to something about via pg_hba.conf or similar. Saying \"use\n> > in-band authentication only\", to me, feels much murkier. As the\n> > recipient of that message, I don't know exactly what to do about it,\n> > and it feels like whatever heuristic I adopt might end up being wrong\n> > and something bad happens anyway.\n>\n> Is it maybe just a matter of terminology? If a proxy tells the server,\n> \"This user is logging in. Here's the password I have for them. DO NOT\n> authenticate using anything else,\" and the HBA says to use ident auth\n> for that user, then the server fails the connection. That's what I\n> mean by in-band -- the proxy says, \"here are the credentials for this\n> connection.\" That's it.\n\nI don't think that's quite the right concept. It seems to me that the\nclient is responsible for informing the server of what the situation\nis, and the server is responsible for deciding whether to allow the\nconnection. In your scenario, the client is not only communicating\ninformation (\"here's the password I have got\") but also making demands\non the server (\"DO NOT authenticate using anything else\"). I like the\nfirst part fine, but not the second part.\n\nConsider the scenario where somebody wants to allow a connection that\nis proxied and does not require a password. For example, maybe I have\na group of three machines that all mutually trust each other and the\nnetwork is locked down so that we need not worry about IP spoofing or\nwhatever. Just be doubly sure, they all have SSL certificates so that\nthey can verify that an incoming connection is from one of the other\ntrusted machines. I, as the administrator, want to configure things so\nthat each machine will proxy connections to the others as long as\nlocal user = remote user. When the remote machine receives the\nconnection, it can trust that the request is legitimate provided that\nthe SSL certificate is successfully verified.\n\nThe way I think this should work is, first, on each machine, in the\nproxy configuration, there should be a rule that says \"only proxy\nconnections where local user = remote user\" (and any other rules I\nwant to enforce). Second, in the HBA configuration, there should be a\nrule that says \"if somebody is trying to proxy a connection, it has to\nbe for one of these IPs and they have to authenticate using an SSL\ncertificate\". In this kind of scenario, the client has no business\ndemanding that the server authenticate using the password rather than\nanything else. The server, not the client, is in charge of deciding\nwhich connections to accept; the client's job is only to decide which\nconnections to proxy. And the human being is responsible for making\nsure that the combination of those two things implements the intended\nsecurity policy.\n\n> Agreed. The danger from my end is, I'm trained on configuration\n> formats that have infinite bells and whistles. I don't really want to\n> go too crazy with it.\n\nYeah. If I remember my math well enough, the time required to\nimplement infinite bells and whistles will also be infinite, and as a\nwise man once said, real artists ship.\n\nIt does seem like a good idea, if we can, to make the configuration\nfile format flexible enough that we can easily extend it with more\nbells and whistles later if we so choose. But realistically most\npeople are going to have very simple configurations.\n\n> > and that maybe\n> > has something in common with our existing configuration file syntaxes.\n> > But if we have to invent something new, then we can do that.\n>\n> Okay. Personally I'd like\n> - the ability to set options globally (so filters are optional)\n> - the ability to maintain many options for a specific scope (host? IP\n> range?) without making my config lines grow without bound\n> - the ability to audit a configuration without trusting its comments\n>\n> But getting all of my wishlist into a sane configuration format that\n> handles all the use cases is the tricky part. I'll think about it.\n\nNobody seemed too keen on my proposal of a bunch of tab-separated\nfields; maybe we're all traumatized from pg_hba.conf and should look\nfor something more complex with a real parser. I thought that\ntab-separated fields might be good enough and simple to implement, but\nit doesn't matter how simple it is to implement if nobody likes it. We\ncould do something that looks more like a series of if-then rules,\ne.g.\n\ntarget-host 127.0.0.0/8 => reject\nauthentication-method scram => accept\nreject\n\nBut it's only a hop, skip and a jump from there to something that\nlooks an awful lot like a full-blown programing language, and maybe\nthat's even the right idea, but, oh, the bike-shedding!\n\nCue someone to suggest that it's about time we embed a Lua interpreter.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 6 Feb 2023 11:22:11 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Fri, Feb 3, 2023 at 3:47 AM Andres Freund <andres@anarazel.de> wrote:\n> On 2023-02-02 09:28:03 -0500, Robert Haas wrote:\n> > I don't know what you mean by this. DML doesn't confer privileges. If\n> > code gets executed and runs with the replication user's credentials,\n> > that could lead to privilege escalation, but just moving rows around\n> > doesn't, at least not in the database sense.\n>\n> Executing DML ends up executing code. Think predicated/expression\n> indexes, triggers, default expressions etc. If a badly written trigger\n> etc can be tricked to do arbitrary code exec, an attack will be able to\n> run with the privs of the run-as user. How bad that is is influenced to\n> some degree by the amount of privileges that user has.\n\nI spent some time studying this today. I think you're right. What I'm\nconfused about is: why do we consider this situation even vaguely\nacceptable? Isn't this basically an admission that our logical\nreplication security model is completely and totally broken and we\nneed to fix it somehow and file for a CVE number? Like, in released\nbranches, you can't even have a subscription owned by a non-superuser.\nBut any non-superuser can set a default expression or create an enable\nalways trigger and sure enough, if that table is replicated, the\nsystem will run that trigger as the subscription owner, who is a\nsuperuser. Which AFAICS means that if a non-superuser owns a table\nthat is part of a subscription, they can instantly hack superuser.\nWhich seems, uh, extremely bad. Am I missing something?\n\nBased on other remarks you made upthread, it seems like we ought to be\ndoing the actual replication as the table owner, since the table owner\nhas to be prepared for executable code attached to the table to be\nre-run on rows in the table at any table when somebody does a REINDEX.\nAnd then, in master, where there's some provision for non-superuser\nsubscription owners, we maybe need to re-think the privileges required\nto replicate into a table in the first place. I don't think that\nhaving I/U/D permissions on a table is really sufficient to justify\nperforming those operations *as the table owner*; perhaps the check\nought to be whether you have the privileges of the table owner.\n\n--\nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 6 Feb 2023 14:07:39 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-02-06 14:07:39 -0500, Robert Haas wrote:\n> On Fri, Feb 3, 2023 at 3:47 AM Andres Freund <andres@anarazel.de> wrote:\n> > On 2023-02-02 09:28:03 -0500, Robert Haas wrote:\n> > > I don't know what you mean by this. DML doesn't confer privileges. If\n> > > code gets executed and runs with the replication user's credentials,\n> > > that could lead to privilege escalation, but just moving rows around\n> > > doesn't, at least not in the database sense.\n> >\n> > Executing DML ends up executing code. Think predicated/expression\n> > indexes, triggers, default expressions etc. If a badly written trigger\n> > etc can be tricked to do arbitrary code exec, an attack will be able to\n> > run with the privs of the run-as user. How bad that is is influenced to\n> > some degree by the amount of privileges that user has.\n> \n> I spent some time studying this today. I think you're right. What I'm\n> confused about is: why do we consider this situation even vaguely\n> acceptable? Isn't this basically an admission that our logical\n> replication security model is completely and totally broken and we\n> need to fix it somehow and file for a CVE number? Like, in released\n> branches, you can't even have a subscription owned by a non-superuser.\n> But any non-superuser can set a default expression or create an enable\n> always trigger and sure enough, if that table is replicated, the\n> system will run that trigger as the subscription owner, who is a\n> superuser. Which AFAICS means that if a non-superuser owns a table\n> that is part of a subscription, they can instantly hack superuser.\n> Which seems, uh, extremely bad. Am I missing something?\n\nIt's decidedly not great, yes. I don't know if it's quite a CVE type issue,\nafter all, the same is true for any other type of query the superuser\nexecutes. But at the very least the documentation needs to be better, with a\nbig red box making sure the admin is aware of the problem.\n\nI think we need some more fundamental ways to deal with this issue, including\nbut not restricted to the replication context. Some potentially relevant\ndiscussion is in this thread:\nhttps://postgr.es/m/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel%40j-davis.com\n\nI don't agree with Jeff's proposal, but I think there's some worthwhile ideas\nin the idea + followups.\n\n\n> And then, in master, where there's some provision for non-superuser\n> subscription owners, we maybe need to re-think the privileges required\n> to replicate into a table in the first place. I don't think that\n> having I/U/D permissions on a table is really sufficient to justify\n> performing those operations *as the table owner*; perhaps the check\n> ought to be whether you have the privileges of the table owner.\n\nYes, I think we ought to check role membership, including non-inherited\nmemberships.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 6 Feb 2023 11:18:38 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Feb 6, 2023 at 2:18 PM Andres Freund <andres@anarazel.de> wrote:\n> It's decidedly not great, yes. I don't know if it's quite a CVE type issue,\n> after all, the same is true for any other type of query the superuser\n> executes. But at the very least the documentation needs to be better, with a\n> big red box making sure the admin is aware of the problem.\n\nI don't think that's the same thing at all. A superuser executing a\nquery interactively can indeed cause all sorts of bad things to\nhappen, but you don't have to log in as superuser and run DML queries\non tables owned by unprivileged users, and you shouldn't.\n\nBut what we're talking about here is -- the superuser comes along and\nsets up logical replication in the configuration in what seems to be\nexactly the way it was intended to be used, and now any user who can\nlog into the subscriber node can become superuser for free whenever\nthey want, without the superuser doing anything at all, even logging\nin. Saying it's \"not ideal\" seems like you're putting it in the same\ncategory as \"the cheese got moldy in the fridge\" but to me it sounds\nmore like \"the fridge exploded and the house is on fire.\"\n\nIf we were to document this, I assume that the warning we would add to\nthe documentation would look like this:\n\n<-- begin documentation text -->\nPretty much don't ever use logical replication. In any normal\nconfiguration, it lets every user on your system escalate to superuser\nwhenever they want. It is possible to make it safe, if you make sure\nall the tables on the replica are owned by the superuser and none of\nthem have any triggers, defaults, expression indexes, or anything else\nassociated with them that might execute any code while replicating.\nBut notice that this makes logical replication pretty much useless for\none of its intended purposes, which is high availability, because if\nyou actually fail over, you're going to then have to change the owners\nof all of those tables and apply any missing triggers, defaults,\nexpression indexes, or anything like that which you may want to have.\nAnd then to fail back you're going to have to remove all of that stuff\nagain and once again make the tables superuser-owned. That's obviously\npretty impractical, so you probably shouldn't use logical replication\nat all until we get around to fixing this. You might wonder why we\nimplemented a feature that can't be used in any kind of normal way\nwithout completely and totally breaking your system security -- but\ndon't ask us, we don't know, either!\n<-- end documentation text -->\n\nHonestly, this makes the CREATEROLE exploit that I fixed recently in\nmaster look like a walk in the park. Sure, it's a pain for service\nproviders, who might otherwise use it, but most normal users don't and\nwouldn't no matter how it worked, and really are not going to care.\nBut people do use logical replication, and it seems to me that the\nissue you're describing here means that approximately 100% of those\ninstallations have a vulnerability allowing any local user who owns a\ntable or can create one to escalate to superuser. Far from being not\nquite a CVE issue, that seems substantially more serious than most\nthings we get CVEs for.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 6 Feb 2023 14:40:18 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Feb 1, 2023 at 4:02 PM Andres Freund <andres@anarazel.de> wrote:\n> On 2023-01-30 15:32:34 -0500, Robert Haas wrote:\n> > I had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\n> > TO in terms of permissions checks.\n>\n> As long as owner and run-as are the same, I think it's strongly\n> preferrable to *not* require pg_create_subscription.\n\nOK.\n\n> > Another question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\n> > SUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\n> > superuser and password_required false is set.\n>\n> I don't really see a benefit in allowing it, so I'm inclined to go for\n> the more restrictive option. But this is a really weakly held opinion.\n\nI went back and forth on this and ended up with what you propose here.\nIt's simpler to explain this way.\n\n> > + /* Is the use of a password mandatory? */\n> > + must_use_password = MySubscription->passwordrequired &&\n> > + !superuser_arg(MySubscription->owner);\n>\n> There's a few repetitions of this - perhaps worth putting into a helper?\n\nI don't think so. It's slightly different each time, because it's\npulling data out of different data structures.\n\n> This still leaks the connection on error, no?\n\nI've attempted to fix this in v4, attached.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com","msg_date":"Tue, 7 Feb 2023 16:56:55 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 2/6/23 08:22, Robert Haas wrote:\n> I don't think that's quite the right concept. It seems to me that the\n> client is responsible for informing the server of what the situation\n> is, and the server is responsible for deciding whether to allow the\n> connection. In your scenario, the client is not only communicating\n> information (\"here's the password I have got\") but also making demands\n> on the server (\"DO NOT authenticate using anything else\"). I like the\n> first part fine, but not the second part.\n\nFor what it's worth, making a negative demand during authentication is\npretty standard: if you visit example.com and it tells you \"I need your\nOS login password and Social Security Number to authenticate you,\" you\nhave the option of saying \"no thanks\" and closing the tab.\n\nIt's not really about protecting the server at that point; the server\ncan protect itself. It's about protecting *you*. Allowing the proxy to\npin a specific set of authentication details to the connection is just a\nway for it to close the tab on a server that would otherwise pull some\nother piece of ambient authority out of it.\n\nIn a hypothetical world where the server presented the client with a\nlist of authentication options before allowing any access, this would\nmaybe be a little less convoluted to solve. For example, a proxy seeing\na SASL list of\n\n- ANONYMOUS\n- EXTERNAL\n\ncould understand that both methods allow the client to assume the\nauthority of the proxy itself. So if its client isn't allowed to do\nthat, the proxy realizes something is wrong (either it, or its target\nserver, has been misconfigured or is under attack), and it can close the\nconnection *before* the server runs login triggers.\n\n> In this kind of scenario, the client has no business\n> demanding that the server authenticate using the password rather than\n> anything else. The server, not the client, is in charge of deciding\n> which connections to accept; the client's job is only to decide which\n> connections to proxy.\n\nThis sounds like a reasonable separation of responsibilities on the\nsurface, but I think it's subtly off. The entire confused-deputy problem\nspace revolves around the proxy being unable to correctly decide which\nconnections to allow unless it also knows why the connections are being\nauthorized.\n\nYou've constructed an example where that's not a concern: everything's\nsymmetrical, all proxies operate with the same authority, and internal\nusers are identical to external users. But the CVE that led to the\npassword requirement, as far as I can tell, dealt with asymmetry. The\nproxy had the authority to connect locally to a user, and the clients\nhad the authority to connect to other machines' users, but those users\nweren't the same and were not mutually trusting.\n\n> And the human being is responsible for making\n> sure that the combination of those two things implements the intended\n> security policy.\n\nSure, but upthread it was illustrated how difficult it is for even the\npeople implementing the protocol to reason through what's safe and\nwhat's not.\n\nThe primitives we're providing in the protocol are, IMO, difficult to\nwield safely for more complex use cases. We can provide mitigations, and\ndemand that the DBA reason through every combination, and tell them\n\"don't do that\" when they screw up or come across a situation that our\nmitigations can't paper over. But I think we can solve the root problem\ninstead.\n\n> We\n> could do something that looks more like a series of if-then rules,\n> e.g.\n> \n> target-host 127.0.0.0/8 => reject\n> authentication-method scram => accept\n> reject\n\nYeah, I think something based on allow/deny is going to be the most\nintuitive.\n\n> But it's only a hop, skip and a jump from there to something that\n> looks an awful lot like a full-blown programing language, and maybe\n> that's even the right idea, but, oh, the bike-shedding!\n\nEh. Someone will demand Turing-completeness eventually, but you don't\nhave to listen. :D\n\n--Jacob\n\n\n","msg_date":"Thu, 9 Feb 2023 13:46:04 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Mon, 2023-02-06 at 14:40 -0500, Robert Haas wrote:\n> On Mon, Feb 6, 2023 at 2:18 PM Andres Freund <andres@anarazel.de>\n> wrote:\n> > It's decidedly not great, yes. I don't know if it's quite a CVE\n> > type issue,\n> > after all, the same is true for any other type of query the\n> > superuser\n> > executes. But at the very least the documentation needs to be\n> > better, with a\n> > big red box making sure the admin is aware of the problem.\n> \n> I don't think that's the same thing at all. A superuser executing a\n> query interactively can indeed cause all sorts of bad things to\n> happen, but you don't have to log in as superuser and run DML queries\n> on tables owned by unprivileged users, and you shouldn't.\n\nThere are two questions:\n\n1. Is the security situation with logical replication bad? Yes. You\nnicely summarized just how bad.\n\n2. Is it the same situation as accessing a table owned by a user you\ndon't absolutely trust? \n\nRegardless of how the second question is answered, it won't diminish\nyour point that logical replication is in a bad state. If another\nsituation is also bad, we should fix that too.\n\nAnd I think the DML situation is really bad, too. Anyone reading our\ndocumentation would find extensive explanations about GRANT/REVOKE, and\npuzzle over the fine details of exactly how much they trust user foo.\nDo I trust foo enough for WITH GRANT OPTION? Does foo really need to\nsee all of the columns of this table, or just a subset?\n\nBut there's no obvious mention that user foo must trust you absolutely\nin order to exercise the GRANT at all, because you (as table owner) can\ntrivially cause foo to execute arbitrary code. There's no warning or\nhint or suggestion at runtime to know that you are about to execute\nsomeone else's code with your privileges or that it might be dangerous.\n\nIt gets worse. Let's say that user foo figures that out, and they're\nextra cautious to SET SESSION AUTHORIZATION or SET ROLE to drop their\nprivileges before accessing a table. No good: the table owner can just\ncraft their arbitrary code with a \"RESET SESSION AUTHORIZATION\" or a\n\"RESET ROLE\" at the top, and the code will still execute with the\nprivileges of user foo.\n\nSo I don't think \"shouldn't\" is quite good enough. In the first place,\nthe user needs to know that the risk exists. Second, what if they\nactually do want to access a table owned by someone else for whatever\nreason -- how do they do that safely?\n\nI can't resist mentioning that these are all SECURITY INVOKER problems.\nSECURITY INVOKER is insecure unless the invoker absolutely trusts the\ndefiner, and that only really makes sense if the definer is a superuser\n(or something very close). That's why we keep adding exceptions with\nSECURITY_RESTRICTED_OPERATION, which is really just a way to silently\nignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\n\nAt some point we need to ask: \"when is SECURITY INVOKER both safe and\nuseful?\" and contain it to those cases, rather than silently ignoring\nit in an expanding list of cases.\n\nI know that the response here is that SECURITY DEFINER is somehow\nworse. Maybe for superuser-defined functions, it is. But basically, the\nproblems with SECURITY DEFINER all amount to \"the author of the code\nneeds to be careful\", which is a lot more intuitive than the problems\nwith SECURITY INVOKER.\n\nAnother option is having some kind SECURITY NONE that would run the\ncode as a very limited-privilege user that can basically only access\nthe catalog. That would be useful for running default expressions and\nthe like without the definer or invoker needing to be careful.\n\n\n-- \nJeff Davis\nPostgreSQL Contributor Team - AWS\n\n\n\n\n","msg_date":"Wed, 22 Feb 2023 09:18:34 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Feb 22, 2023, at 9:18 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> Another option is having some kind SECURITY NONE that would run the\n> code as a very limited-privilege user that can basically only access\n> the catalog. That would be useful for running default expressions and\n> the like without the definer or invoker needing to be careful.\n\nAnother option is to execute under the intersection of their privileges, where both the definer and the invoker need the privileges in order for the action to succeed. That would be more permissive than the proposed SECURITY NONE, while still preventing either party from hijacking privileges of the other.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 22 Feb 2023 09:27:19 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\n> Another option is to execute under the intersection of their\n> privileges, where both the definer and the invoker need the\n> privileges in order for the action to succeed. That would be more\n> permissive than the proposed SECURITY NONE, while still preventing\n> either party from hijacking privileges of the other.\n\nInteresting idea, I haven't heard of something like that being done\nbefore. Is there some precedent for that or a use case where it's\nhelpful?\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Wed, 22 Feb 2023 10:49:42 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"\n\n> On Feb 22, 2023, at 10:49 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n> \n> On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\n>> Another option is to execute under the intersection of their\n>> privileges, where both the definer and the invoker need the\n>> privileges in order for the action to succeed. That would be more\n>> permissive than the proposed SECURITY NONE, while still preventing\n>> either party from hijacking privileges of the other.\n> \n> Interesting idea, I haven't heard of something like that being done\n> before. Is there some precedent for that or a use case where it's\n> helpful?\n\nNo current use case comes to mind, but I proposed it for event triggers one or two development cycles ago, to allow for non-superuser event trigger owners. The problems associated with allowing non-superusers to create and own event triggers were pretty similar to the problems being discussed in this thread.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Wed, 22 Feb 2023 11:12:05 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 2/22/23 14:12, Mark Dilger wrote:\n>> On Feb 22, 2023, at 10:49 AM, Jeff Davis <pgsql@j-davis.com> wrote:\n>> On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\n>>> Another option is to execute under the intersection of their\n>>> privileges, where both the definer and the invoker need the\n>>> privileges in order for the action to succeed. That would be more\n>>> permissive than the proposed SECURITY NONE, while still preventing\n>>> either party from hijacking privileges of the other.\n>> \n>> Interesting idea, I haven't heard of something like that being done\n>> before. Is there some precedent for that or a use case where it's\n>> helpful?\n> > No current use case comes to mind, but I proposed it for event\n> triggers one or two development cycles ago, to allow for\n> non-superuser event trigger owners. The problems associated with\n> allowing non-superusers to create and own event triggers were pretty\n> similar to the problems being discussed in this thread.\n\n\nThe intersection of privileges is used, for example, in multi-level \nsecurity contexts where the intersection of the network-allowed levels \nand the subject allowed levels is used to bracket what can be accessed \nand how.\n\nOther examples I found with a quick search:\n\nhttps://docs.oracle.com/javase/8/docs/api/java/security/AccessController.html#doPrivileged-java.security.PrivilegedAction-java.security.AccessControlContext-\n\nhttps://learn.microsoft.com/en-us/dotnet/api/system.security.permissions.dataprotectionpermission.intersect?view=dotnet-plat-ext-7.0\n\n\n-- \nJoe Conway\nPostgreSQL Contributors Team\nRDS Open Source Databases\nAmazon Web Services: https://aws.amazon.com\n\n\n\n","msg_date":"Wed, 22 Feb 2023 15:25:44 -0500","msg_from":"Joe Conway <mail@joeconway.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Feb 22, 2023 at 12:18 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> There are two questions:\n>\n> 1. Is the security situation with logical replication bad? Yes. You\n> nicely summarized just how bad.\n>\n> 2. Is it the same situation as accessing a table owned by a user you\n> don't absolutely trust?\n>\n> Regardless of how the second question is answered, it won't diminish\n> your point that logical replication is in a bad state. If another\n> situation is also bad, we should fix that too.\n\nWell said.\n\n> So I don't think \"shouldn't\" is quite good enough. In the first place,\n> the user needs to know that the risk exists. Second, what if they\n> actually do want to access a table owned by someone else for whatever\n> reason -- how do they do that safely?\n\nGood question. I don't think we currently have a good answer.\n\n> I can't resist mentioning that these are all SECURITY INVOKER problems.\n> SECURITY INVOKER is insecure unless the invoker absolutely trusts the\n> definer, and that only really makes sense if the definer is a superuser\n> (or something very close). That's why we keep adding exceptions with\n> SECURITY_RESTRICTED_OPERATION, which is really just a way to silently\n> ignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\n\nThat's an interesting way to look at it. I think there are perhaps two\ndifferent possible perspectives here. One possibility is to take the\nview that you've adopted here, and blame it on SECURITY INVOKER. The\nother possibility, at least as I see it, is to blame it on the fact\nthat we have so many places to attach executable code to tables and\nvery few ways for people using those tables to limit their exposure to\nsuch code. Suppose Alice owns a table and attaches a trigger to it. If\nBob inserts into that table, I think we have to run the trigger,\nbecause Alice is entitled to assume that, for example, any BEFORE\ntriggers she might have defined that block certain kinds of inserts\nare actually going to block those inserts; any constraints that she\nhas applied to the table are going to be enforced against all new\nrows; and any default expressions she supplies are actually going to\nwork. I think Bob has to be OK with those things too; otherwise, he\njust shouldn't insert anything into the table.\n\nBut Bob doesn't have to be OK with Alice's code changing the session\nstate, or executing DML or DDL with his permissions. I wonder if\nthat's where we should be trying to insert restrictions here. Right\nnow, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\nfunction or procedure that runs under a different user ID than the\nsession user from poisoning the session state. But I'm thinking that\nmaybe the problem isn't really with code running under a different\nuser ID. It's with running code *provided by* a different user ID.\nMaybe we should stop thinking about the security context as something\nthat you set when you switch to running as a different user ID, and\nstart thinking about it as something that needs to be set based on the\nrelationship between the user that provided the code and the session\nuser. If they're not the same, some restrictions are probably\nappropriate, except I think in the case where the user who provided\nthe code can become the session user anyway.\n\n> Another option is having some kind SECURITY NONE that would run the\n> code as a very limited-privilege user that can basically only access\n> the catalog. That would be useful for running default expressions and\n> the like without the definer or invoker needing to be careful.\n\nThis might be possible, but I have some doubts about how difficult it\nwould be to get all the details right. We'd need to make sure that\nthis limited-privilege user couldn't ever create a table, or own one,\nor be granted any privileges to do anything other than the minimal set\nof things it's supposed to be able to do, or poison the session state,\netc. And it would have weird results like current_user returning the\nname of the limited-privilege user rather than any of the users\ninvolved in the operation. Maybe that's all OK, but I find it more\nappealing to try to think about what kinds of operations can be\nperformed in what contexts than to invent entirely new users.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 27 Feb 2023 10:45:06 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2023-02-27 at 10:45 -0500, Robert Haas wrote:\n\n> Suppose Alice owns a table and attaches a trigger to it. If\n> Bob inserts into that table, I think we have to run the trigger,\n> because Alice is entitled to assume that, for example, any BEFORE\n> triggers she might have defined that block certain kinds of inserts\n> are actually going to block those inserts; any constraints that she\n> has applied to the table are going to be enforced against all new\n> rows; and any default expressions she supplies are actually going to\n> work.\n\nTrue, but I still find myself suspending my disbelief. Which of these\nuse cases make sense for SECURITY INVOKER?\n\n> I think Bob has to be OK with those things too; otherwise, he\n> just shouldn't insert anything into the table.\n\nRight, but why should Bob's privileges be needed to do any of those\nthings? Any difference in privileges, for those use cases, could only\neither get in the way of achieving Alice's goals, or cause a security\nproblem for Bob.\n\n> But Bob doesn't have to be OK with Alice's code changing the session\n> state, or executing DML or DDL with his permissions.\n\nWhat's left? Should Bob be OK with Alice's code using his permissions\nfor anything?\n\n> I wonder if\n> that's where we should be trying to insert restrictions here. Right\n> now, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\n> function or procedure that runs under a different user ID than the\n> session user from poisoning the session state. But I'm thinking that\n> maybe the problem isn't really with code running under a different\n> user ID. It's with running code *provided by* a different user ID.\n> Maybe we should stop thinking about the security context as something\n> that you set when you switch to running as a different user ID, and\n> start thinking about it as something that needs to be set based on\n> the\n> relationship between the user that provided the code and the session\n> user. If they're not the same, some restrictions are probably\n> appropriate, except I think in the case where the user who provided\n> the code can become the session user anyway.\n\nI think you are saying that we should still run Alice's code with the\nprivileges of Bob, but somehow make that safe(r) for Bob. Is that\nright?\n\nThat sounds hard, and I'm still stuck at the \"why\" question. Why do we\nwant to run Alice's code with Bob's permissions?\n\nThe answers I have so far are abstract. For instance, maybe it's a\nclever SRF that takes table names as inputs and you want people to only\nbe able to use the clever SRF with tables they have privileges on. But\nthat's not what most functions do, and it's certainly not what most\ndefault expressions do.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 27 Feb 2023 10:25:29 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Mon, 2023-02-27 at 10:45 -0500, Robert Haas wrote:\n> > Suppose Alice owns a table and attaches a trigger to it. If\n> > Bob inserts into that table, I think we have to run the trigger,\n> > because Alice is entitled to assume that, for example, any BEFORE\n> > triggers she might have defined that block certain kinds of inserts\n> > are actually going to block those inserts; any constraints that she\n> > has applied to the table are going to be enforced against all new\n> > rows; and any default expressions she supplies are actually going to\n> > work.\n> \n> True, but I still find myself suspending my disbelief. Which of these\n> use cases make sense for SECURITY INVOKER?\n\nI do think there are some use-cases for it, but agree that it'd be\nbetter to encourage more use of SECURITY DEFINER and one approach to\nthat might be to have a way for users to explicitly say \"don't run code\nthat isn't mine or a superuser's with my privileges.\" Of course, we\nneed to make sure it's possible to write safe SECURITY DEFINER functions\nand to be clear about how to do that to avoid the risk in the other\ndirection. We also need to provide some additonal functions along the\nlines of \"calling_role()\" or similar (so that the function can know who\nthe actual role is that's running the trigger) for the common case of\nauditing or needing to know the calling role for RLS or similar.\n\nI don't think we'd be able to get away with just getting rid of SECURITY\nINVOKER entirely or even in changing the current way triggers (or\nfunctions in views, etc) are run by default.\n\n> > I think Bob has to be OK with those things too; otherwise, he\n> > just shouldn't insert anything into the table.\n> \n> Right, but why should Bob's privileges be needed to do any of those\n> things? Any difference in privileges, for those use cases, could only\n> either get in the way of achieving Alice's goals, or cause a security\n> problem for Bob.\n> \n> > But Bob doesn't have to be OK with Alice's code changing the session\n> > state, or executing DML or DDL with his permissions.\n> \n> What's left? Should Bob be OK with Alice's code using his permissions\n> for anything?\n\nI don't know about trying to define that X things are ok and Y things\nare not, that seems like it would be more confusing and difficult to\nwork with. Regular SELECT queries that pull data that Bob has access to\nbut Alice doesn't is a security issue too, were Alice to install a\nfunction that Bob calls which writes that data into a place that Alice\ncould then access it. Perhaps if we could allow Bob to say \"these\nthings are ok for Alice's code to access\" then it could work ... but if\nthat's what is going on then the code could run with Alice's permissions\nand Bob could use our nice and granular GRANT/RLS system to say what\nAlice is allowed to access.\n\n> > I wonder if\n> > that's where we should be trying to insert restrictions here. Right\n> > now, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\n> > function or procedure that runs under a different user ID than the\n> > session user from poisoning the session state. But I'm thinking that\n> > maybe the problem isn't really with code running under a different\n> > user ID. It's with running code *provided by* a different user ID.\n> > Maybe we should stop thinking about the security context as something\n> > that you set when you switch to running as a different user ID, and\n> > start thinking about it as something that needs to be set based on\n> > the\n> > relationship between the user that provided the code and the session\n> > user. If they're not the same, some restrictions are probably\n> > appropriate, except I think in the case where the user who provided\n> > the code can become the session user anyway.\n> \n> I think you are saying that we should still run Alice's code with the\n> privileges of Bob, but somehow make that safe(r) for Bob. Is that\n> right?\n> \n> That sounds hard, and I'm still stuck at the \"why\" question. Why do we\n> want to run Alice's code with Bob's permissions?\n> \n> The answers I have so far are abstract. For instance, maybe it's a\n> clever SRF that takes table names as inputs and you want people to only\n> be able to use the clever SRF with tables they have privileges on. But\n> that's not what most functions do, and it's certainly not what most\n> default expressions do.\n\ncurrent_role / current_user are certainly common as a default\nexpression. I agree that that's more of an edge case that would be nice\nto solve in a different way though. I do think there's some other use\ncases for SECURITY INVOKER but not enough folks understand the security\nrisk associated with it and it'd be good for us to improve on that\nsituation.\n\nThanks,\n\nStephen","msg_date":"Mon, 27 Feb 2023 14:10:02 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> I think you are saying that we should still run Alice's code with the\n> privileges of Bob, but somehow make that safe(r) for Bob. Is that\n> right?\n\nYeah. That's the idea I was floating, at least.\n\n> That sounds hard, and I'm still stuck at the \"why\" question. Why do we\n> want to run Alice's code with Bob's permissions?\n>\n> The answers I have so far are abstract. For instance, maybe it's a\n> clever SRF that takes table names as inputs and you want people to only\n> be able to use the clever SRF with tables they have privileges on. But\n> that's not what most functions do, and it's certainly not what most\n> default expressions do.\n\nI guess I have a pretty hard time imagining that we can just\nobliterate SECURITY INVOKER entirely. It seems fundamentally\nreasonable to me that Alice might want to make some code available to\nbe executed in the form of a function or procedure but without\noffering to execute it with her own privileges. But I think maybe\nyou're asking a different question, which is whether when the code is\nattached to a table we ought to categorically switch to the table\nowner before executing it. I'm less sure about the answer to that\nquestion. We already take the position that VACUUM always runs as the\ntable owner, and while VACUUM runs index expressions but not for\nexample triggers, why not just be consistent and run all code that is\ntied to the table as the table owner, all the time?\n\nMaybe that's the right thing to do, but I think it would inevitably\nbreak some things for some users. Alice might choose to write her\ntriggers or default expressions in ways that rely on them running with\nBob's permissions in any number of ways. For instance, maybe those\nfunctions issue a SELECT query against an RLS-enabled table, such that\nthe answer depends on whose privileges are used to run the query. More\nsimply, she might refer to CURRENT_ROLE, say to record who inserted\nany particular row into her table, which seems like a totally\nreasonable thing to want to do. If she was feeling really clever, she\nmight even have designed queries that she's using inside those\ntriggers or default expressions to fail if Bob doesn't have enough\npermissions to do some particular modification that he's attempting,\nand thus block certain kinds of access to her own tables. That would\nbe pretty weird and perhaps too clever by half, but the point is that\nthe current behavior is probably known to many, many users and we\nreally can't know what they've done that depends on that. If we change\nany behavior here, some people are going to notice those changes, and\nthey may not like them.\n\nTo put that another way, we're not talking about a black-and-white\nsecurity vulnerability here, like a buffer overrun that allows for\narbitrary code execution. We're talking about a set of semantics that\nseem to be somewhat fragile and vulnerable to spawning security\nproblems. Nobody wants those security problems, for sure. But it\ndoesn't follow that nobody is relying on the semantics.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 27 Feb 2023 16:13:59 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2023-02-27 at 14:10 -0500, Stephen Frost wrote:\n> I do think there are some use-cases for it, but agree that it'd be\n> better to encourage more use of SECURITY DEFINER and one approach to\n> that might be to have a way for users to explicitly say \"don't run\n> code\n> that isn't mine or a superuser's with my privileges.\" \n\nI tried that:\n\nhttps://www.postgresql.org/message-id/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel@j-davis.com\n\nbut Andres pointed out some problems with my implementation. They\ndidn't seem easily fixable, but perhaps with more effort it could work\n(run all the expressions as security definer, as well?).\n\n> Of course, we\n> need to make sure it's possible to write safe SECURITY DEFINER\n> functions\n> and to be clear about how to do that to avoid the risk in the other\n> direction.\n\nAgreed. Perhaps we can force search_path to be set for SECURITY\nDEFINER, and require that the temp schema be explicitly included rather\nthan the current \"must be at the end\". We could also provide a way to\nturn public access off in the same statement, so that you don't need to\nuse a transaction block to keep the function private.\n\n> I don't think we'd be able to get away with just getting rid of\n> SECURITY\n> INVOKER entirely or even in changing the current way triggers (or\n> functions in views, etc) are run by default.\n\nI didn't propose anything radical. I'm just trying to get some\nagreement that SECURITY INVOKER is central to a lot of our security\nwoes, and that we should be treating it with skepticism on a\nfundamental level.\n\nIndividual proposals for how to get away from SECURITY INVOKER should\nbe evaluated on their merits (i.e. don't break a bunch of stuff).\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Mon, 27 Feb 2023 16:03:15 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2023-02-27 at 16:13 -0500, Robert Haas wrote:\n> On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > I think you are saying that we should still run Alice's code with\n> > the\n> > privileges of Bob, but somehow make that safe(r) for Bob. Is that\n> > right?\n> \n> Yeah. That's the idea I was floating, at least.\n\nIsn't that a hard problem; maybe impossible?\n\n> \n> I guess I have a pretty hard time imagining that we can just\n> obliterate SECURITY INVOKER entirely.\n\nOf course not.\n\n> It seems fundamentally\n> reasonable to me that Alice might want to make some code available to\n> be executed in the form of a function or procedure but without\n> offering to execute it with her own privileges.\n\nIt also seems fundamentally reasonable that if someone grants you\nprivileges on one of their tables, it might be safe to access it.\n\nI'm sure there are a few use cases for SECURITY INVOKER, but they are\nquite narrow.\n\nPerhaps most frustratingly, even if none of the users on a system has\nany use case for SECURITY INVOKER, they still must all live in fear of\naccessing each others' tables, because at any time a SECURITY INVOKER\nfunction could be attached to one of the tables.\n\nI feel like we are giving up mainstream utility and safety in exchange\nfor contrived or exceptional cases. That's not a good trade.\n\n> We already take the position that VACUUM always runs as the\n> table owner, and while VACUUM runs index expressions but not for\n> example triggers, why not just be consistent and run all code that is\n> tied to the table as the table owner, all the time?\n\nI'd also extend this to default expressions and other code that can be\nexecuted implicitly.\n\n> Maybe that's the right thing to do\n\nIf it's the right place to go, then I think we should consider\nreasonable steps to take in that direction that don't cause unnecessary\nbreakage.\n\n> , but I think it would inevitably\n> break some things for some users.\n\nNot all steps would be breaking changes, and a lot of those steps are\nthings we should do anyway. We could make it easier to write safe\nSECURITY DEFINER functions, provide more tools for users to opt-out of\nexecuting SECURITY INVOKER code, provide a way for superusers to safely\ndrop privileges, document the problems with security invoker and what\nto do about them, etc.\n\n> Alice might choose to write her\n> triggers or default expressions in ways that rely on them running\n> with\n> Bob's permissions in any number of ways.\n\nSure, breakage is possible, and we should mitigate it.\n\nBut we also shouldn't exaggerate it -- for instance, others have\nproposed that we run code as the table owner for logical subscriptions,\nand that's going to break things in the same way. Arguably, if we are\ngoing to break something, it's better to break it consistently rather\nthan one subsystem at a time.\n\nBack to the $SUBJECT, if we allow non-superusers to run subscriptions,\nand the subscription runs the code as the table owner, that might also\nlead to some weird behavior for triggers that rely on SECURITY INVOKER\nsemantics.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 27 Feb 2023 16:37:26 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Mon, 2023-02-27 at 14:10 -0500, Stephen Frost wrote:\n> > I do think there are some use-cases for it, but agree that it'd be\n> > better to encourage more use of SECURITY DEFINER and one approach to\n> > that might be to have a way for users to explicitly say \"don't run\n> > code\n> > that isn't mine or a superuser's with my privileges.\" \n> \n> I tried that:\n> \n> https://www.postgresql.org/message-id/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel@j-davis.com\n> \n> but Andres pointed out some problems with my implementation. They\n> didn't seem easily fixable, but perhaps with more effort it could work\n> (run all the expressions as security definer, as well?).\n\nPresumably. Ultimately, I tend to agree it won't be easy. That doesn't\nmean it's not a worthwhile effort.\n\n> > Of course, we\n> > need to make sure it's possible to write safe SECURITY DEFINER\n> > functions\n> > and to be clear about how to do that to avoid the risk in the other\n> > direction.\n> \n> Agreed. Perhaps we can force search_path to be set for SECURITY\n> DEFINER, and require that the temp schema be explicitly included rather\n> than the current \"must be at the end\". We could also provide a way to\n> turn public access off in the same statement, so that you don't need to\n> use a transaction block to keep the function private.\n\nWe do pretty strongly encourage a search_path setting for SECURITY\nDEFINER today.. That said, I'm not against pushing on that harder. The\nissue about temporary schemas is a more difficult issue... but frankly,\nI'd like an option to say \"no temporary schemas should be allowed in my\nsearch path\" when it comes to a security definer function.\n\n> > I don't think we'd be able to get away with just getting rid of\n> > SECURITY\n> > INVOKER entirely or even in changing the current way triggers (or\n> > functions in views, etc) are run by default.\n> \n> I didn't propose anything radical. I'm just trying to get some\n> agreement that SECURITY INVOKER is central to a lot of our security\n> woes, and that we should be treating it with skepticism on a\n> fundamental level.\n\nSure, but if we want to make progress then we have to provide a\ndirection for folks to go in that's both secure and convenient.\n\n> Individual proposals for how to get away from SECURITY INVOKER should\n> be evaluated on their merits (i.e. don't break a bunch of stuff).\n\nOf course. That said ... we don't want to spend a lot of time\ngoing in a direction that won't bear fruit; I'm hopeful that this\ndirection will though.\n\nThanks,\n\nStephen","msg_date":"Mon, 27 Feb 2023 21:31:47 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> Not all steps would be breaking changes, and a lot of those steps are\n> things we should do anyway. We could make it easier to write safe\n> SECURITY DEFINER functions, provide more tools for users to opt-out of\n> executing SECURITY INVOKER code, provide a way for superusers to safely\n> drop privileges, document the problems with security invoker and what\n> to do about them, etc.\n\nAgreed.\n\n> But we also shouldn't exaggerate it -- for instance, others have\n> proposed that we run code as the table owner for logical subscriptions,\n> and that's going to break things in the same way. Arguably, if we are\n> going to break something, it's better to break it consistently rather\n> than one subsystem at a time.\n\nI tend to agree with this.\n\n> Back to the $SUBJECT, if we allow non-superusers to run subscriptions,\n> and the subscription runs the code as the table owner, that might also\n> lead to some weird behavior for triggers that rely on SECURITY INVOKER\n> semantics.\n\nIndeed.\n\nThanks,\n\nStephen","msg_date":"Mon, 27 Feb 2023 21:38:35 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > Yeah. That's the idea I was floating, at least.\n>\n> Isn't that a hard problem; maybe impossible?\n\nIt doesn't seem that hard to me; maybe I'm missing something.\n\nThe existing SECURITY_RESTRICTED_OPERATION flag basically prevents you\nfrom tinkering with the session state. If we also had a similar flags\nlike DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or just\na combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\npretty close to what we need. The idea would be that, when a user\nexecutes a function or procedure owned by a user that they don't trust\ncompletely, we'd set\nSECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRITES_PROHIBITED.\nAnd we could provide a user with a way to express the degree of trust\nthey have in some other user or perhaps even some specific function,\ne.g.\n\nSET trusted_roles='alice:read';\n\n...could mean that I trust alice to read from the database with my\npermissions, should I happen to run code provided by her in SECURITY\nINVOKER modacke.\n\nI'm sure there's some details to sort out here, e.g. around security\nrelated to the trusted_roles GUC itself. But I don't really see a\nfundamental problem. We can invent arbitrary flags that prohibit\nclasses of operations that are of concern, set them by default in\ncases where concern is justified, and then give users who want the\ncurrent behavior some kind of escape hatch that causes those flags to\nnot get set after all. Not only does such a solution not seem\nimpossible, I can possibly even imagine back-patching it, depending on\nexactly what the shape of the final solution is, how important we\nthink it is to get a fix out there, and how brave I'm feeling that\nday.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 28 Feb 2023 08:37:02 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-02-22 09:18:34 -0800, Jeff Davis wrote:\n> I can't resist mentioning that these are all SECURITY INVOKER problems.\n> SECURITY INVOKER is insecure unless the invoker absolutely trusts the\n> definer, and that only really makes sense if the definer is a superuser\n> (or something very close). That's why we keep adding exceptions with\n> SECURITY_RESTRICTED_OPERATION, which is really just a way to silently\n> ignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\n> \n> At some point we need to ask: \"when is SECURITY INVOKER both safe and\n> useful?\" and contain it to those cases, rather than silently ignoring\n> it in an expanding list of cases.\n\nI can only repeat myself in stating that SECURITY DEFINER solves none of the\nrelevant issues. I included several examples of why it doesn't in the recent\nthread about \"blocking SECURITY INVOKER\". E.g. that default arguments of\nSECDEF functions are evaluated with the current user's privileges, not the\nfunction owner's privs:\n\nhttps://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 28 Feb 2023 11:28:30 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, 2023-02-28 at 11:28 -0800, Andres Freund wrote:\n> I can only repeat myself in stating that SECURITY DEFINER solves none\n> of the\n> relevant issues. I included several examples of why it doesn't in the\n> recent\n> thread about \"blocking SECURITY INVOKER\". E.g. that default arguments\n> of\n> SECDEF functions are evaluated with the current user's privileges,\n> not the\n> function owner's privs:\n> \n> https://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\n\nI was speaking a bit loosely, using \"SECURITY DEFINER\" to mean the\nsemantics of executing code as the one who wrote it. I didn't\nspecifically mean the function marker, because as you pointed out in\nthe other thread, that's not enough.\n\n From your email it looks like there is still a path forward:\n\n\"The proposal to not trust any expressions controlled by untrusted\nusers at least allows to prevent execution of code, even if it doesn't\nprovide a way to execute the code in a safe manner. Given that we\ndon't have the former, it seems foolish to shoot for the latter.\"\n\nAnd later:\n\n\"I think the combination of\na) a setting that restricts evaluation of any non-trusted expressions,\n independent of the origin\nb) an easy way to execute arbitrary statements within\n SECURITY_RESTRICTED_OPERATION\"\n\nMy takeaway from that thread was that we need a mechanism to deal with\nnon-function code (e.g. default expressions) first; but once we have\nthat, it opens up the design space to better solutions or at least\nmitigations. Is that right?\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Tue, 28 Feb 2023 12:36:38 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, 2023-02-28 at 08:37 -0500, Robert Haas wrote:\n> The existing SECURITY_RESTRICTED_OPERATION flag basically prevents\n> you\n> from tinkering with the session state.\n\nCurrently, every time we set that flag we also run all the code as the\ntable owner.\n\nYou're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\nwith the new security flags, but not switch to the table owner, right?\n\n> If we also had a similar flags\n> like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or\n> just\n> a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\n> pretty close to what we need. The idea would be that, when a user\n> executes a function or procedure \n\nOr default expressions, I presume. If we at least agree on this point,\nthen I think we should try to find a way to treat these other hunks of\ncode in a secure way (which I think is what Andres was suggesting).\n\n> owned by a user that they don't trust\n> completely, we'd set\n> SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRIT\n> ES_PROHIBITED.\n\nIt seems like you're saying to basically just keep the user ID the\nsame, and maybe keep USAGE privileges, but not be able to do anything\nelse? Might be useful. Kind of like running it as a nobody user but\nwithout the problems you mentioned. Some details to think about, I'm\nsure.\n\n> And we could provide a user with a way to express the degree of trust\n> they have in some other user or perhaps even some specific function,\n> e.g.\n> \n> SET trusted_roles='alice:read';\n> \n> ...could mean that I trust alice to read from the database with my\n> permissions, should I happen to run code provided by her in SECURITY\n> INVOKER modacke.\n\nI'm not very excited about inventing a new privilege language inside a\nGUC, but perhaps a simpler form could be a reasonable mitigation (or at\nleast a starting place).\n\n> I'm sure there's some details to sort out here, e.g. around security\n> related to the trusted_roles GUC itself. But I don't really see a\n> fundamental problem. We can invent arbitrary flags that prohibit\n> classes of operations that are of concern, set them by default in\n> cases where concern is justified, and then give users who want the\n> current behavior some kind of escape hatch that causes those flags to\n> not get set after all. Not only does such a solution not seem\n> impossible, I can possibly even imagine back-patching it, depending\n> on\n> exactly what the shape of the final solution is, how important we\n> think it is to get a fix out there, and how brave I'm feeling that\n> day.\n\nUnless the trusted roles defaults to '*', then I think it will still\nbreak some things.\n\n\nOne of my key tests for user-facing proposals is whether the\ndocumentation will be reasonable or not. Most of these proposals to\nmake SECURITY INVOKER less bad fail that test.\n\nEach of these ideas and sub-ideas affect the semantics, and should be\ndocumented. But how do we document that some code runs as you, some as\nthe person who wrote it, sometimes we obey SECURITY INVOKER and\nsometimes we ignore it and use DEFINER semantics, some code is outside\na function and always executes as the invoker, some code has some\nsecurity flags, and some code has more security flags, code can change\nbetween the time you look at it and the time it runs, and it's all\nfiltered through GUCs with their own privilege sub-language?\n\nOK, let's assume that we have all of that documented, then how do we\nguide users on what reasonable best practices are for the GUC settings,\netc.? Or do we just say \"this is mechanically how all these parts work,\ngood luck assembling it into a secure system!\". [ Note: I feel like\nthis is the state we are in now. Even if technically we don't have live\nsecurity bugs that I'm aware of, we are setting users up for security\nproblems. ]\n\nOn the other hand, if we focus on executing code as the user who wrote\nit in most places, then the documentation will be something like: \"you\ndefined the table, you wrote the code, it runs as you, here are some\nbest practices for writing secure code\". And we have some different\ndocumentation for writing a cool SECURITY INVOKER function and how to\nget other users to trust you enough to run it. That sounds a LOT more\nunderstandable for users.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Tue, 28 Feb 2023 13:01:05 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Tue, 2023-02-28 at 08:37 -0500, Robert Haas wrote:\n> > The existing SECURITY_RESTRICTED_OPERATION flag basically prevents\n> > you\n> > from tinkering with the session state.\n> \n> Currently, every time we set that flag we also run all the code as the\n> table owner.\n> \n> You're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\n> with the new security flags, but not switch to the table owner, right?\n\nI'm having trouble following this too, I have to admit. If we aren't\nchanging who we're running the code under.. but making it so that the\ncode isn't actually able to do anything then that doesn't strike me as\nlikely to actually be useful? Surely things like triggers which are\nused to update another table or insert into another table what happened\non the table with the trigger need to be allowed to modify the database-\nhow do we make that possible while the code runs as the invoker and not\nthe table owner when the table owner is the one who gets to write the\ncode?\n\n> > If we also had a similar flags\n> > like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or\n> > just\n> > a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\n> > pretty close to what we need. The idea would be that, when a user\n> > executes a function or procedure \n> \n> Or default expressions, I presume. If we at least agree on this point,\n> then I think we should try to find a way to treat these other hunks of\n> code in a secure way (which I think is what Andres was suggesting).\n\nWould need to apply to functions in views and functions in RLS too,\nalong wth default expressions and everything else that could be defined\nby one person and run by another.\n\n> > owned by a user that they don't trust\n> > completely, we'd set\n> > SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRIT\n> > ES_PROHIBITED.\n> \n> It seems like you're saying to basically just keep the user ID the\n> same, and maybe keep USAGE privileges, but not be able to do anything\n> else? Might be useful. Kind of like running it as a nobody user but\n> without the problems you mentioned. Some details to think about, I'm\n> sure.\n\nWhile there's certainly some use-cases where a completely unprivileged\nuser would work, there's certainly an awful lot where it wouldn't.\nHaving that as an option might be interesting for those much more\nlimited use-cases and maybe you could even say \"only run functions which\nare owned by a superuser or X roles\" but it's certainly not a general\nsolution to the problem.\n\n> > And we could provide a user with a way to express the degree of trust\n> > they have in some other user or perhaps even some specific function,\n> > e.g.\n> > \n> > SET trusted_roles='alice:read';\n> > \n> > ...could mean that I trust alice to read from the database with my\n> > permissions, should I happen to run code provided by her in SECURITY\n> > INVOKER modacke.\n> \n> I'm not very excited about inventing a new privilege language inside a\n> GUC, but perhaps a simpler form could be a reasonable mitigation (or at\n> least a starting place).\n\nI'm pretty far down the path of \"wow that looks really difficult to work\nwith\", to put it nicely.\n\n> > I'm sure there's some details to sort out here, e.g. around security\n> > related to the trusted_roles GUC itself. But I don't really see a\n> > fundamental problem. We can invent arbitrary flags that prohibit\n> > classes of operations that are of concern, set them by default in\n> > cases where concern is justified, and then give users who want the\n> > current behavior some kind of escape hatch that causes those flags to\n> > not get set after all. Not only does such a solution not seem\n> > impossible, I can possibly even imagine back-patching it, depending\n> > on\n> > exactly what the shape of the final solution is, how important we\n> > think it is to get a fix out there, and how brave I'm feeling that\n> > day.\n> \n> Unless the trusted roles defaults to '*', then I think it will still\n> break some things.\n\nDefaulting to an option that is \"don't break anything\" while giving\nusers flexibility to test out other, more secure, options seems like it\nwould be a pretty reasonable way forward, generally. That said.. I\ndon't really think this particular approach ends up being a good\ndirection to go in...\n\n> One of my key tests for user-facing proposals is whether the\n> documentation will be reasonable or not. Most of these proposals to\n> make SECURITY INVOKER less bad fail that test.\n\nand this is certainly a very good point as to why.\n\nThanks,\n\nStephen","msg_date":"Tue, 28 Feb 2023 21:22:48 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Feb 28, 2023 at 4:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> You're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\n> with the new security flags, but not switch to the table owner, right?\n\nCorrect.\n\n> Or default expressions, I presume. If we at least agree on this point,\n> then I think we should try to find a way to treat these other hunks of\n> code in a secure way (which I think is what Andres was suggesting).\n\nYeah, or any other expressions. Basically impose restrictions when the\nuser running the code is not the same as the user who provided the\ncode.\n\n> It seems like you're saying to basically just keep the user ID the\n> same, and maybe keep USAGE privileges, but not be able to do anything\n> else? Might be useful. Kind of like running it as a nobody user but\n> without the problems you mentioned. Some details to think about, I'm\n> sure.\n\nYep.\n\n> I'm not very excited about inventing a new privilege language inside a\n> GUC, but perhaps a simpler form could be a reasonable mitigation (or at\n> least a starting place).\n\nI'm not very sure about this part, either. I think we need some way of\nshutting off whatever new controls we impose, but the shape of it is\nunclear to me and I think there are a bunch of problems.\n\n> Unless the trusted roles defaults to '*', then I think it will still\n> break some things.\n\nDefinitely. IMHO, it's OK to break some things, certainly in a major\nrelease and maybe even in a minor release. But we don't want to break\nmore things that we really need to break. And as you say, we want the\nrestrictions to be comprehensible.\n\n> Each of these ideas and sub-ideas affect the semantics, and should be\n> documented. But how do we document that some code runs as you, some as\n> the person who wrote it, sometimes we obey SECURITY INVOKER and\n> sometimes we ignore it and use DEFINER semantics, some code is outside\n> a function and always executes as the invoker, some code has some\n> security flags, and some code has more security flags, code can change\n> between the time you look at it and the time it runs, and it's all\n> filtered through GUCs with their own privilege sub-language?\n>\n> OK, let's assume that we have all of that documented, then how do we\n> guide users on what reasonable best practices are for the GUC settings,\n> etc.? Or do we just say \"this is mechanically how all these parts work,\n> good luck assembling it into a secure system!\". [ Note: I feel like\n> this is the state we are in now. Even if technically we don't have live\n> security bugs that I'm aware of, we are setting users up for security\n> problems. ]\n>\n> On the other hand, if we focus on executing code as the user who wrote\n> it in most places, then the documentation will be something like: \"you\n> defined the table, you wrote the code, it runs as you, here are some\n> best practices for writing secure code\". And we have some different\n> documentation for writing a cool SECURITY INVOKER function and how to\n> get other users to trust you enough to run it. That sounds a LOT more\n> understandable for users.\n\nWhat I was imagining is that we would document something like: A table\ncan have executable code associated with it in a variety of ways. For\nexample, it can have triggers, default expressions, check constraints,\nor row-level security filters. In most cases, these expressions are\nexecuted with the privileges of the user performing the operation on\nthe table, except when SECURITY DEFINER functions are used. Because\nthese expressions are set by the table owner and executed by the users\naccessing the table, there is a risk that the table owner could\ninclude malicious code that usurps the privileges of the user\naccessing the table. For this reason, these expressions are, by\ndefault, restricted from doing <things>. If you want to allow those\noperations, you can <something>.\n\nI agree that running code as the table owner is helpful in a bunch of\nscenarios, but I also don't think it fixes everything. You earlier\nmentioned that switching to the table owner seems to be just a way of\nturning SECURITY INVOKER into SECURITY DEFINER in random places, or\nmaybe that's not exactly what you said but that's what I took from it.\nAnd I think that's right. If we just slather user context switches\neverywhere, I'm not actually very sure that's going to be\ncomprehensible behavior: if my trigger function is SECURITY INVOKER,\nwhy is it getting executed as me, not the inserting user? I also think\nthere are plenty of cases where that could just replace the current\nset of security problems with a new set of security problems. If the\ntrigger function is SECURITY INVOKER, then the user who wrote it\ndoesn't have to worry about securing it against attacks by users\naccessing the table; it's just running with the permissions of the\nuser performing the DML. Maybe there are correctness issues if you\ndon't lock down search_path etc., but there's no security compromise\nbecause there's no user ID switching. As soon as you magically turn\nthat into a SECURITY DEFINER function, you've provided a way for the\nusers performing DML to attack the table owner.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 1 Mar 2023 10:05:42 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Robert Haas (robertmhaas@gmail.com) wrote:\n> On Tue, Feb 28, 2023 at 4:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > Or default expressions, I presume. If we at least agree on this point,\n> > then I think we should try to find a way to treat these other hunks of\n> > code in a secure way (which I think is what Andres was suggesting).\n> \n> Yeah, or any other expressions. Basically impose restrictions when the\n> user running the code is not the same as the user who provided the\n> code.\n\nWould this have carve-outs for things like \"except if the user providing\nthe code is trusted/superuser\"? Seems like that would be necessary for\nthe function to be able to do more-or-less anything, but then I worry\nthat there's superuser-owned code which could leak information or be\nused by a malicious owner as that code would still be running as the\ninvoking user.. Perhaps we could say that the function also has to be\nleakproof, but that isn't quite the same issue and therefore it seems\nlike we'd need to decorate all of the functions with another flag that's\nallowed to be run in this manner.\n\nRandom thought- what if the function has a NOTIFY in it with a payload\nof some kind of sensitive information?\n\n> > Unless the trusted roles defaults to '*', then I think it will still\n> > break some things.\n> \n> Definitely. IMHO, it's OK to break some things, certainly in a major\n> release and maybe even in a minor release. But we don't want to break\n> more things that we really need to break. And as you say, we want the\n> restrictions to be comprehensible.\n\nReally hard to say if whatever this is is OK for back-patching and\nbreaking minor releases without knowing exactly what is getting broken\n... but it'd have to be a very clear edge case of what gets broken for\nit to be sensible for breaking in a minor release without a very clear\nvulnerability or such that's being fixed with a simple work-around.\nJust making all auditing triggers break in a minor release certainly\nwouldn't be acceptable, as an example that I imagine we all agree with.\n\n> > Each of these ideas and sub-ideas affect the semantics, and should be\n> > documented. But how do we document that some code runs as you, some as\n> > the person who wrote it, sometimes we obey SECURITY INVOKER and\n> > sometimes we ignore it and use DEFINER semantics, some code is outside\n> > a function and always executes as the invoker, some code has some\n> > security flags, and some code has more security flags, code can change\n> > between the time you look at it and the time it runs, and it's all\n> > filtered through GUCs with their own privilege sub-language?\n> >\n> > OK, let's assume that we have all of that documented, then how do we\n> > guide users on what reasonable best practices are for the GUC settings,\n> > etc.? Or do we just say \"this is mechanically how all these parts work,\n> > good luck assembling it into a secure system!\". [ Note: I feel like\n> > this is the state we are in now. Even if technically we don't have live\n> > security bugs that I'm aware of, we are setting users up for security\n> > problems. ]\n> >\n> > On the other hand, if we focus on executing code as the user who wrote\n> > it in most places, then the documentation will be something like: \"you\n> > defined the table, you wrote the code, it runs as you, here are some\n> > best practices for writing secure code\". And we have some different\n> > documentation for writing a cool SECURITY INVOKER function and how to\n> > get other users to trust you enough to run it. That sounds a LOT more\n> > understandable for users.\n> \n> What I was imagining is that we would document something like: A table\n> can have executable code associated with it in a variety of ways. For\n> example, it can have triggers, default expressions, check constraints,\n> or row-level security filters. In most cases, these expressions are\n> executed with the privileges of the user performing the operation on\n> the table, except when SECURITY DEFINER functions are used. Because\n> these expressions are set by the table owner and executed by the users\n> accessing the table, there is a risk that the table owner could\n> include malicious code that usurps the privileges of the user\n> accessing the table. For this reason, these expressions are, by\n> default, restricted from doing <things>. If you want to allow those\n> operations, you can <something>.\n\nWell, one possible answer to 'something' might be 'use SECURITY DEFINER\nfunctions which are owned by a role allowed to do <things>'. Note that\nthat doesn't have to be the table owner though, it could be a much more\nconstrained role. That approach would allow us to leverage the existing\nGRANT/RLS/et al system for what's allowed and avoid having to create new\nthings like a complex permission system inside of a GUC for users to\nhave to understand.\n\n> I agree that running code as the table owner is helpful in a bunch of\n> scenarios, but I also don't think it fixes everything. You earlier\n> mentioned that switching to the table owner seems to be just a way of\n> turning SECURITY INVOKER into SECURITY DEFINER in random places, or\n> maybe that's not exactly what you said but that's what I took from it.\n> And I think that's right. If we just slather user context switches\n> everywhere, I'm not actually very sure that's going to be\n> comprehensible behavior: if my trigger function is SECURITY INVOKER,\n> why is it getting executed as me, not the inserting user? I also think\n> there are plenty of cases where that could just replace the current\n> set of security problems with a new set of security problems. If the\n> trigger function is SECURITY INVOKER, then the user who wrote it\n> doesn't have to worry about securing it against attacks by users\n> accessing the table; it's just running with the permissions of the\n> user performing the DML. Maybe there are correctness issues if you\n> don't lock down search_path etc., but there's no security compromise\n> because there's no user ID switching. As soon as you magically turn\n> that into a SECURITY DEFINER function, you've provided a way for the\n> users performing DML to attack the table owner.\n\nI agree that we don't want to just turn \"SECURITY INVOKER function when\nrun as a trigger\" into SECURITY DEFINER, and that SECURITY DEFINER\nfunctions need to be able to be written in a mannor that limits the risk\nof them being able to be abused to gain control of the role which owns\nthe function (the latter being something we've worked on but should\ncertainly continue to improve on, independently of any of this..).\n\nAlong the same general vein of \"don't break things\", perhaps an approach\nwould be a GUC that users can enable that says \"don't allow code that\ndoes something dangerous (again, need to figure out how to do that..)\nwhen it's written by someone else to run with my privileges (and\ntherefore isn't a SECURITY DEFINER function)\". The idea here being that\nwe want to encourage users to enable that, maybe we eventually enable it\nby default in a new major version, and push people in the direction of\nwriting secure SECURITY DEFINER functions for the cases where they\nactually need the trigger, or such, to do something beyond whatever we\ndefine as being 'safe'. This keeps the GUC as a simple on/off or enum\nlike row_security, fails the action when something not-safe is being\nattempted, and gives the flexibility of our existing GRANT/RLS system\nfor the case where a SECURITY DEFINER function is created to perform the\noperation. This does still need some supporting functions like 'calling\nrole' or such because there could be many many roles doing an INSERT\ninto a table which runs a trigger and that trigger runs as some other\nrole, but the other role could be one that has more privileges than the\nINSERT'ing role and therefore it needs to implement additional checks on\nthe operation to limit what the INSERT'ing role is allowed to do.\n\nI do worry about asking function authors to effectively rewrite these\nkinds of permission checks and wonder if there's a way we could make it\neasier for them- perhaps a kind of function that's SECURITY DEFINER in\nthat it runs as the owner of the function, but it sets a flag saying\n\"only allow things that the function owner is allowed to do AND the\ncalling user is allowed to do\", similar to the 'intersection of\nprivileges' idea mentioned elsewhere on this thread.\n\nThanks,\n\nStephen","msg_date":"Wed, 1 Mar 2023 10:48:22 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Mar 1, 2023 at 10:48 AM Stephen Frost <sfrost@snowman.net> wrote:\n> > Yeah, or any other expressions. Basically impose restrictions when the\n> > user running the code is not the same as the user who provided the\n> > code.\n>\n> Would this have carve-outs for things like \"except if the user providing\n> the code is trusted/superuser\"? Seems like that would be necessary for\n> the function to be able to do more-or-less anything, but then I worry\n> that there's superuser-owned code which could leak information or be\n> used by a malicious owner as that code would still be running as the\n> invoking user.. Perhaps we could say that the function also has to be\n> leakproof, but that isn't quite the same issue and therefore it seems\n> like we'd need to decorate all of the functions with another flag that's\n> allowed to be run in this manner.\n\nYes, I think there can be carve-outs based on the relationship of the\nusers involved -- if the user who provided the code is the superuser\nor some other user who can anyway run whatever they want as the user\nperforming the operation, then there's no point in imposing any\nrestrictions -- and I think there can also be some way of setting\npolicy. I proposed a GUC in an earlier email, and you proposed one\nwith somewhat different semantics in this email, and I'm not sure that\neither of those things in particular is right or that we ought to be\nusing a GUC for this at all. However, there should almost certainly be\nSOME way for the superuser to turn any new restrictions off, and there\nshould probably also be some way for an unprivileged user to say \"you\nknow, I am totally OK with running any code that alice provides --\njust go with it.\"\n\nI don't think we're at a point where we can conclude on what those\nmechanisms should look like just yet, but I think that everyone who\nhas spoken up agrees that they ought to exist, assuming we go in this\ndirection at all.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 1 Mar 2023 12:33:10 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-03-01 at 10:05 -0500, Robert Haas wrote:\n> For this reason, these expressions are, by\n> default, restricted from doing <things>.\n\nThe hard part is defining <things> without resorting to a bunch of\nspecial cases, and also in a way that doesn't break a bunch of stuff.\n\n> You earlier\n> mentioned that switching to the table owner seems to be just a way of\n> turning SECURITY INVOKER into SECURITY DEFINER in random places, or\n> maybe that's not exactly what you said but that's what I took from\n> it.\n\nYeah, though I glossed over some details, see below.\n\n> If we just slather user context switches\n> everywhere, I'm not actually very sure that's going to be\n> comprehensible behavior: if my trigger function is SECURITY INVOKER,\n> why is it getting executed as me, not the inserting user?\n\nLet's consider other expressions first. The proposal is that all\nexpressions attached to a table should run as the table owner (set\naside compatibility concerns for a moment). If those expressions call a\nSECURITY INVOKER function, the invoker would need to be the table owner\nas well. Users could get confused by that, but I think it's\ndocumentable and understandable; and it's really the only thing that\nmakes sense -- otherwise changing the user is completely useless.\n\nWe should consider triggers as just another expression being executed,\nand the invoker is the table owner. The problem is that it's a little\nannoying to users because they probably defined the function for the\nsole purpose of being a trigger function for a single table, and it\nmight look as though the SECURITY INVOKER label was ignored.\n\nBut there is a difference, which I glossed over before: SECURITY\nINVOKER on a trigger function would still have significance, because\nthe function owner (definer) and table owner (invoker) could still be\ndifferent in the case of a trigger, just like in an expression.\n\nThis goes back to my point that SECURITY INVOKER is more complex for us\nto document and for users to understand. The user *must* understand who\nthe invoker is in various contexts. That's the situation today and\nthere's no escaping it. We aren't making things any worse, at least as\nlong as we can sort out compatibility in a reasonable way.\n\n(Aside: I'm having some serious concerns about how the invoker of a\nfunction called in a view is not the view definer. That's another thing\nwe'll need to fix, because it's another way of putting SECURITY INVOKER\ncode in front of someone without them knowing.)\n\n(Aside: We should take a second look at the security invoker views\nbefore we release them. I know that I learned some things during this\ndiscussion and a fresh look might be useful.)\n\n> As soon as you magically turn\n> that into a SECURITY DEFINER function, you've provided a way for the\n> users performing DML to attack the table owner.\n\nI don't think it's magic, as I said above. But I assume that your more\ngeneral point is that if we take some responsibility away from the\ninvoker and place it on the definer, then it creates room for new kinds\nof problems. And I agree.\n\nThe point of moving responsibility to the definer is that the definer\ncan actually do something to protect themselves (nail down search_path,\nrestrict USAGE privs, and avoid dynamic SQL); whereas the invoker is\nnearly helpless.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Wed, 01 Mar 2023 10:13:55 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Mar 1, 2023 at 1:13 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> I don't think it's magic, as I said above. But I assume that your more\n> general point is that if we take some responsibility away from the\n> invoker and place it on the definer, then it creates room for new kinds\n> of problems. And I agree.\n>\n> The point of moving responsibility to the definer is that the definer\n> can actually do something to protect themselves (nail down search_path,\n> restrict USAGE privs, and avoid dynamic SQL); whereas the invoker is\n> nearly helpless.\n\nI think there's some truth to that allegation, but I think it largely\ncomes from the fact that we've given very little thought or attention\nto this problem. We have a section in the documentation on writing\nSECURITY DEFINER functions safely because we've known for a long time\nthat it's dangerous and we've provided some (imperfect) tools for\ndealing with it, like allowing a SET search_path clause to be attached\nto a function definition. We have no comparable documentation section\nabout SECURITY INVOKER because we haven't historically taken that\nseriously as a security hazard and we have no tools to make it safe.\nBut we could, as with what I'm proposing here, or the user/function\ntrust mechanism previously proposed by Noah, or various other ideas\nthat we might have.\n\nI don't like the idea of saying that we're not going to try to invent\nanything new and just push people into using the stuff we already\nhave. The stuff we have for security SECURITY DEFINER functions is not\nvery good. True, it's better than what we have for protecting against\nthe risks inherent in SECURITY INVOKER, but that's not saying much:\nanything at all is better than nothing. But it's easy to forget a SET\nsearch_path clause on one of your functions, or to include something\nin that search path that's not actually safe, or to have a problem\nthat isn't blocked by just setting search_path. Also, not that it's\nthe most important consideration here, but putting a SET clause on\nyour functions is really kind of expensive if what the function does\nis trivial, which if you're using it in an index expression or a\ndefault expression, will often be the case. I don't want to pretend\nlike I have all the answers here, but I find it really hard to believe\nthat pushing people to do the same kind of nonsense that's currently\nrequired when writing a SECURITY DEFINER function for a lot of their\nother functions as well is going to be a win. I think it will probably\nsuck.\n\nTo be fair, it's possible that there's no solution to this class of\nproblems that *doesn't* suck, but I think we should look a lot harder\nbefore coming to that conclusion. I've come to agree with your\ncontention that we're not taking the hazards of SECURITY INVOKER\nnearly seriously enough, but I think you're underestimating the\nhazards that SECURITY DEFINER poses, and overestimating how easy it is\nto avoid them.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 1 Mar 2023 16:06:14 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-03-01 at 16:06 -0500, Robert Haas wrote:\n\n> To be fair, it's possible that there's no solution to this class of\n> problems that *doesn't* suck, but I think we should look a lot harder\n> before coming to that conclusion.\n\nFair enough. The situation is bad enough that I'm willing to consider a\npretty wide range of solutions and mitigations that might otherwise be\nunappealing.\n\nI think there might be something promising in your idea to highly\nrestrict the privileges of code attached to a table. A lot of\nexpressions are really simple and don't need much to be both useful and\nsafe. We may not need the exact same solution for both default\nexpressions and triggers. Some details to work through, though.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Wed, 01 Mar 2023 14:27:25 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-02-28 12:36:38 -0800, Jeff Davis wrote:\n> On Tue, 2023-02-28 at 11:28 -0800, Andres Freund wrote:\n> > I can only repeat myself in stating that SECURITY DEFINER solves none\n> > of the\n> > relevant issues. I included several examples of why it doesn't in the\n> > recent\n> > thread about \"blocking SECURITY INVOKER\". E.g. that default arguments\n> > of\n> > SECDEF functions are evaluated with the current user's privileges,\n> > not the\n> > function owner's privs:\n> > \n> > https://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\n> \n> I was speaking a bit loosely, using \"SECURITY DEFINER\" to mean the\n> semantics of executing code as the one who wrote it. I didn't\n> specifically mean the function marker, because as you pointed out in\n> the other thread, that's not enough.\n\nOh, ok.\n\n\n> From your email it looks like there is still a path forward:\n> \n> \"The proposal to not trust any expressions controlled by untrusted\n> users at least allows to prevent execution of code, even if it doesn't\n> provide a way to execute the code in a safe manner. Given that we\n> don't have the former, it seems foolish to shoot for the latter.\"\n> \n> And later:\n> \n> \"I think the combination of\n> a) a setting that restricts evaluation of any non-trusted expressions,\n> independent of the origin\n> b) an easy way to execute arbitrary statements within\n> SECURITY_RESTRICTED_OPERATION\"\n> \n> My takeaway from that thread was that we need a mechanism to deal with\n> non-function code (e.g. default expressions) first; but once we have\n> that, it opens up the design space to better solutions or at least\n> mitigations. Is that right?\n\nI doubt it's realistic to change the user for all kinds of expressions\nindividually. A query can involve expressions controlled by many users,\nchanging the current user in a super granular way seems undesirable from a\nperformance and complexity pov.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 1 Mar 2023 16:14:30 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-02-28 08:37:02 -0500, Robert Haas wrote:\n> On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > > Yeah. That's the idea I was floating, at least.\n> >\n> > Isn't that a hard problem; maybe impossible?\n>\n> It doesn't seem that hard to me; maybe I'm missing something.\n>\n> The existing SECURITY_RESTRICTED_OPERATION flag basically prevents you\n> from tinkering with the session state. If we also had a similar flags\n> like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or just\n> a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\n> pretty close to what we need. The idea would be that, when a user\n> executes a function or procedure owned by a user that they don't trust\n> completely, we'd set\n> SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRITES_PROHIBITED.\n> And we could provide a user with a way to express the degree of trust\n> they have in some other user or perhaps even some specific function,\n> e.g.\n\nISTM that this would require annotating most functions in the system. There's\nmany problems besides accessing database contents. Just a few examples:\n\n- dblink functions to access another system / looping back\n- pg_read_file()/pg_file_write() allows almost arbitrary mischief\n- pg_stat_reset[_shared]()\n- creating/dropping logical replication slots\n- use untrusted PL functions\n- many more\n\nA single wrongly annotated function would be sufficient to escape. This\nincludes user defined functions.\n\n\nThis basically proposes that we can implement a safe sandbox for executing\narbitrary code in a privileged context. IMO history suggests that that's a\nhard thing to do.\n\nAm I missing something?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 1 Mar 2023 16:34:40 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Mar 1, 2023 at 7:34 PM Andres Freund <andres@anarazel.de> wrote:\n> ISTM that this would require annotating most functions in the system. There's\n> many problems besides accessing database contents. Just a few examples:\n>\n> - dblink functions to access another system / looping back\n> - pg_read_file()/pg_file_write() allows almost arbitrary mischief\n> - pg_stat_reset[_shared]()\n> - creating/dropping logical replication slots\n> - use untrusted PL functions\n> - many more\n>\n> A single wrongly annotated function would be sufficient to escape. This\n> includes user defined functions.\n>\n> This basically proposes that we can implement a safe sandbox for executing\n> arbitrary code in a privileged context. IMO history suggests that that's a\n> hard thing to do.\n\nYeah, that's true, but I don't think switching users all the time is\ngoing to be great either. And it's not like other people haven't gone\nthis way: that's what plperl (not plperlu) is all about, and\nJavaScript running in your browser, and so on. Those things aren't\nproblem-free, of course, but we're all using them.\n\nWhen I was initially thinking about this, I thought that maybe we\ncould just block access to tables and utility statements. That's got\nproblems in both directions. On the one hand, there are functions like\nthe ones you propose here that have side effects which we might not\nwant to allow, and on the other hand, somebody might have an index\nexpression that does a lookup in a table that they \"never change\". The\nlatter case is problematic for non-security reasons, because there's\nan invisible dump-ordering constraint that must be obeyed for\ndump/restore to work at all, but there's no security issue. Still, I'm\nnot sure this idea is completely dead in the water. It doesn't seem\nunreasonable to me that if you have that kind of case, you have to\nsomehow opt into the behavior: yeah, I know that index functions I'm\nexecuting are going to read from tables, and I consent to that. And\nsimilarly, if your index expression calls pg_stat_reset_shared(), that\nprobably ought to be blocked by default too, and if you want to allow\nit, you have to say so. Yes, that does require labelling functions, or\nmaybe putting run-time checks in them:\n\nRequireAvailableCapability(CAP_MODIFY_DATABASE_STATE);\n\nIf that capability isn't available in the present context, the call\nerrors out. That way, it's possible for the required capabilities to\ndepend on the arguments to the function, and we can change markings in\nminor releases without needing catalog changes.\n\nThere's another way of thinking about this problem, which involves\nsupposing that the invoker should only be induced to do things that\nthe definer could also have done. Basically do every privilege check\ntwice, and require that both pass. The problem I have with that is\nthat there are various operations which depend on your identity, not\njust your privileges. For instance, a GRANT statement records a\ngrantor, and a REVOKE statement infers a grantor whose grant is to be\nrevoked. The operation isn't just allowed or disallowed based on who\nperformed it -- it actually does something different depending on who\nperforms it. I believe we have a number of cases like that, and I\nthink that they suggest that that whole model is pretty flawed. Even\nif that were no issue, this also seems extremely complex to implement,\nbecause we have an absolute crap-ton of places that perform privilege\nchecks and getting all of those places to check privileges as a second\nuser seems nightmarish. I also think that it might be lead to\nconfusing error messages: alice tried to do X but we're not allowing\nit because bob isn't allowed to do X. Eh, what? As opposed to the\nsandboxing approach, where I think you get something more like:\n\nERROR: database state cannot be modified now\nDETAIL: The database system is evaluating an index expression.\nHINT: Do $SOMETHING to allow this.\n\nI don't want to press too hard on my idea here. I'm sure it has a\nbunch of problems apart from those already mentioned, and those\nalready mentioned are not trivial. However, I do think there might be\nways to make it work, and I'm not at all convinced that trying to\nswitch users all over the place is going to be be better, either for\nsecurity or usability. Is there some other whole kind of approach we\ncan take here that we haven't discussed yet?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 3 Mar 2023 09:43:21 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Feb 9, 2023 at 4:46 PM Jacob Champion <jchampion@timescale.com> wrote:\n> On 2/6/23 08:22, Robert Haas wrote:\n> > I don't think that's quite the right concept. It seems to me that the\n> > client is responsible for informing the server of what the situation\n> > is, and the server is responsible for deciding whether to allow the\n> > connection. In your scenario, the client is not only communicating\n> > information (\"here's the password I have got\") but also making demands\n> > on the server (\"DO NOT authenticate using anything else\"). I like the\n> > first part fine, but not the second part.\n>\n> For what it's worth, making a negative demand during authentication is\n> pretty standard: if you visit example.com and it tells you \"I need your\n> OS login password and Social Security Number to authenticate you,\" you\n> have the option of saying \"no thanks\" and closing the tab.\n\nNo, that's the opposite, and exactly the point I'm trying to make. In\nthat case, the SERVER says what it's willing to accept, and the CLIENT\ndecides whether or not to provide that. In your proposal, the client\ntells the server which authentication methods to accept.\n\n> In a hypothetical world where the server presented the client with a\n> list of authentication options before allowing any access, this would\n> maybe be a little less convoluted to solve. For example, a proxy seeing\n> a SASL list of\n>\n> - ANONYMOUS\n> - EXTERNAL\n>\n> could understand that both methods allow the client to assume the\n> authority of the proxy itself. So if its client isn't allowed to do\n> that, the proxy realizes something is wrong (either it, or its target\n> server, has been misconfigured or is under attack), and it can close the\n> connection *before* the server runs login triggers.\n\nYep, that totally makes sense to me, but I don't think it's what you proposed.\n\n> This sounds like a reasonable separation of responsibilities on the\n> surface, but I think it's subtly off. The entire confused-deputy problem\n> space revolves around the proxy being unable to correctly decide which\n> connections to allow unless it also knows why the connections are being\n> authorized.\n\nI agree.\n\n> You've constructed an example where that's not a concern: everything's\n> symmetrical, all proxies operate with the same authority, and internal\n> users are identical to external users. But the CVE that led to the\n> password requirement, as far as I can tell, dealt with asymmetry. The\n> proxy had the authority to connect locally to a user, and the clients\n> had the authority to connect to other machines' users, but those users\n> weren't the same and were not mutually trusting.\n\nYeah, agreed. So, I think the point here is that the proxy\nconfiguration (and pg_hba.conf) need to be sufficiently powerful that\neach user can permit the things that make sense in their environment\nand block the things that don't.\n\nI don't think we're really very far apart here, but for some reason\nthe terminology seems to be giving us some trouble. Of course, there's\nalso the small problem of actually finding the time to do some\nmeaningful work on this stuff, rather than just talking....\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 7 Mar 2023 14:04:14 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Tue, Mar 7, 2023 at 11:04 AM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Thu, Feb 9, 2023 at 4:46 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > On 2/6/23 08:22, Robert Haas wrote:\n> > > I don't think that's quite the right concept. It seems to me that the\n> > > client is responsible for informing the server of what the situation\n> > > is, and the server is responsible for deciding whether to allow the\n> > > connection. In your scenario, the client is not only communicating\n> > > information (\"here's the password I have got\") but also making demands\n> > > on the server (\"DO NOT authenticate using anything else\"). I like the\n> > > first part fine, but not the second part.\n> >\n> > For what it's worth, making a negative demand during authentication is\n> > pretty standard: if you visit example.com and it tells you \"I need your\n> > OS login password and Social Security Number to authenticate you,\" you\n> > have the option of saying \"no thanks\" and closing the tab.\n>\n> No, that's the opposite, and exactly the point I'm trying to make. In\n> that case, the SERVER says what it's willing to accept, and the CLIENT\n> decides whether or not to provide that. In your proposal, the client\n> tells the server which authentication methods to accept.\n\nAh, that's a (the?) sticking point. In my example, the client doesn't\ntell the server which methods to accept. The client tells the server\nwhich method the *client* has the ability to use. (Or, implicitly,\nwhich methods it refuses to use.)\n\nThat shouldn't lose any power, security-wise, because the server is\nlooking for an intersection of the two sets. And the client already\nhas the power to do that for almost every form of authentication,\nexcept the ambient methods.\n\nI don't think I necessarily like that option better than SASL-style,\nbut hopefully that clarifies it somewhat?\n\n> I don't think we're really very far apart here, but for some reason\n> the terminology seems to be giving us some trouble.\n\nAgreed.\n\n> Of course, there's\n> also the small problem of actually finding the time to do some\n> meaningful work on this stuff, rather than just talking....\n\nAgreed :)\n\n--Jacob\n\n\n","msg_date":"Wed, 8 Mar 2023 11:30:15 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > No, that's the opposite, and exactly the point I'm trying to make. In\n> > that case, the SERVER says what it's willing to accept, and the CLIENT\n> > decides whether or not to provide that. In your proposal, the client\n> > tells the server which authentication methods to accept.\n>\n> Ah, that's a (the?) sticking point. In my example, the client doesn't\n> tell the server which methods to accept. The client tells the server\n> which method the *client* has the ability to use. (Or, implicitly,\n> which methods it refuses to use.)\n>\n> That shouldn't lose any power, security-wise, because the server is\n> looking for an intersection of the two sets. And the client already\n> has the power to do that for almost every form of authentication,\n> except the ambient methods.\n>\n> I don't think I necessarily like that option better than SASL-style,\n> but hopefully that clarifies it somewhat?\n\nHmm, yeah, I guess that's OK. I still don't love it, though. It feels\nmore solid to me if the proxy can actually block the connections\nbefore they even happen, without having to rely on a server\ninteraction to figure out what is permissible.\n\nI don't know what you mean by SASL-style, exactly.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 8 Mar 2023 14:40:42 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"Hi,\n\nOn 2023-02-07 16:56:55 -0500, Robert Haas wrote:\n> On Wed, Feb 1, 2023 at 4:02 PM Andres Freund <andres@anarazel.de> wrote:\n> > > + /* Is the use of a password mandatory? */\n> > > + must_use_password = MySubscription->passwordrequired &&\n> > > + !superuser_arg(MySubscription->owner);\n> >\n> > There's a few repetitions of this - perhaps worth putting into a helper?\n> \n> I don't think so. It's slightly different each time, because it's\n> pulling data out of different data structures.\n> \n> > This still leaks the connection on error, no?\n> \n> I've attempted to fix this in v4, attached.\n\nHm - it still feels wrong that we error out in case of failure, despite the\ncomment to the function saying:\n * Returns NULL on error and fills the err with palloc'ed error message.\n\nOther than this, the change looks ready to me.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 8 Mar 2023 11:47:43 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Mar 8, 2023 at 11:40 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > I don't think I necessarily like that option better than SASL-style,\n> > but hopefully that clarifies it somewhat?\n>\n> Hmm, yeah, I guess that's OK.\n\nOkay, cool.\n\n> I still don't love it, though. It feels\n> more solid to me if the proxy can actually block the connections\n> before they even happen, without having to rely on a server\n> interaction to figure out what is permissible.\n\nSure. I don't see a way for the proxy to figure that out by itself,\nthough, going back to my asymmetry argument from before. Only the\nserver truly knows, at time of HBA processing, whether the proxy\nitself has authority. If the proxy knew, it wouldn't be confused.\n\n> I don't know what you mean by SASL-style, exactly.\n\nThat's the one where the server explicitly names all forms of\nauthentication, including the ambient ones (ANONYMOUS, EXTERNAL,\netc.), and requires the client to choose one before running any\nactions on their behalf. That lets the require_auth machinery work for\nthis case, too.\n\n--Jacob\n\n\n","msg_date":"Wed, 8 Mar 2023 14:44:26 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Wed, Mar 8, 2023 at 5:44 PM Jacob Champion <jchampion@timescale.com> wrote:\n>\n> On Wed, Mar 8, 2023 at 11:40 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> > On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\n> > > I don't think I necessarily like that option better than SASL-style,\n> > > but hopefully that clarifies it somewhat?\n> >\n> > Hmm, yeah, I guess that's OK.\n>\n> Okay, cool.\n>\n> > I still don't love it, though. It feels\n> > more solid to me if the proxy can actually block the connections\n> > before they even happen, without having to rely on a server\n> > interaction to figure out what is permissible.\n>\n> Sure. I don't see a way for the proxy to figure that out by itself,\n> though, going back to my asymmetry argument from before. Only the\n> server truly knows, at time of HBA processing, whether the proxy\n> itself has authority. If the proxy knew, it wouldn't be confused.\n>\n> > I don't know what you mean by SASL-style, exactly.\n>\n> That's the one where the server explicitly names all forms of\n> authentication, including the ambient ones (ANONYMOUS, EXTERNAL,\n> etc.), and requires the client to choose one before running any\n> actions on their behalf. That lets the require_auth machinery work for\n> this case, too.\n>\n> --Jacob\n\n\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 9 Mar 2023 09:12:37 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Wed, Mar 8, 2023 at 5:44 PM Jacob Champion <jchampion@timescale.com> wrote:\n> Sure. I don't see a way for the proxy to figure that out by itself,\n> though, going back to my asymmetry argument from before. Only the\n> server truly knows, at time of HBA processing, whether the proxy\n> itself has authority. If the proxy knew, it wouldn't be confused.\n\nThat seems like a circular argument. If you call the problem the\nconfused deputy problem then the issue must indeed be that the deputy\nis confused, and needs to talk to someone else to get un-confused. But\nwhy is the deputy necessarily confused in the first place? Our deputy\nis confused because our code to decide whether to proxy a connection\nor not is super-dumb, but if there's an intrinsic reason it can't be\nsmarter, I don't understand what it is.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 9 Mar 2023 09:17:01 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Thu, Mar 9, 2023 at 6:17 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> That seems like a circular argument. If you call the problem the\n> confused deputy problem then the issue must indeed be that the deputy\n> is confused, and needs to talk to someone else to get un-confused. But\n> why is the deputy necessarily confused in the first place? Our deputy\n> is confused because our code to decide whether to proxy a connection\n> or not is super-dumb,\n\nNo, I think our proxy is confused because it doesn't know what power\nit has, and it can't tell the server what power it wants to use. That\nproblem is independent of the decision to proxy. You're suggesting\nstrengthening the code that makes that decision -- adding an oracle\n(in the form of a DBA) that knows about the confusion and actively\nmitigates it. That's guaranteed to work if the oracle is perfect,\nbecause \"perfect\" is somewhat tautologically defined as \"whatever\nensures secure operation\". But the oracle doesn't reduce the\nconfusion, and DBAs aren't perfect.\n\nIf you want to add a Sheriff Andy to hold Barney Fife's hand [1], that\nwill absolutely make Barney less of a problem, and I'd like to have\nAndy around regardless. But Barney still doesn't know what's going on,\nand when Andy makes a mistake, there will still be trouble. I'd like\nto teach Barney some useful stuff.\n\n> but if there's an intrinsic reason it can't be\n> smarter, I don't understand what it is.\n\nWell... I'm not well-versed enough in this to prove non-existence of a\nsolution. Can you find a solution, using the current protocol, that\ndoesn't make use of perfect out-of-band knowledge? We have a client\nthat will authenticate using any method the server asks it to, even if\nits user intended to use something else. And we have a server that can\neagerly skip client authentication, and then eagerly run code on its\nbehalf, without first asking the client what it's even trying to do.\nThat would be an inherently hostile environment for *any* proxy, not\njust ours.\n\nThanks,\n--Jacob\n\n[1] https://en.wikipedia.org/wiki/The_Andy_Griffith_Show#Premise_and_characters\n\n\n","msg_date":"Fri, 10 Mar 2023 16:00:19 -0800","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Fri, Mar 10, 2023 at 7:00 PM Jacob Champion <jchampion@timescale.com> wrote:\n> On Thu, Mar 9, 2023 at 6:17 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> > That seems like a circular argument. If you call the problem the\n> > confused deputy problem then the issue must indeed be that the deputy\n> > is confused, and needs to talk to someone else to get un-confused. But\n> > why is the deputy necessarily confused in the first place? Our deputy\n> > is confused because our code to decide whether to proxy a connection\n> > or not is super-dumb,\n>\n> No, I think our proxy is confused because it doesn't know what power\n> it has, and it can't tell the server what power it wants to use. That\n> problem is independent of the decision to proxy. You're suggesting\n> strengthening the code that makes that decision -- adding an oracle\n> (in the form of a DBA) that knows about the confusion and actively\n> mitigates it. That's guaranteed to work if the oracle is perfect,\n> because \"perfect\" is somewhat tautologically defined as \"whatever\n> ensures secure operation\". But the oracle doesn't reduce the\n> confusion, and DBAs aren't perfect.\n\nI think this is the root of our disagreement. My understanding of the\nprevious discussion is that people think that the major problem here\nis the wraparound-to-superuser attack. That is, in general, we expect\nthat when we connect to a database over the network, we expect it to\ndo some kind of active authentication, like asking us for a password,\nor asking us for an SSL certificate that isn't just lying around for\nanyone to use. However, in the specific case of a local connection, we\nhave a reliable way of knowing who the remote user is without any kind\nof active authentication, namely 'peer' authentication or perhaps even\n'trust' if we trust all the local users, and so we don't judge it\nunreasonable to allow local connections without any form of active\nauthentication. There can be some scenarios where even over a network\nwe can know the identity of the person connecting with complete\ncertainty, e.g. if endpoints are locked down such that the source IP\naddress is a reliable indicator of who is initiating the connection,\nbut in general when there's a network involved you don't know who the\nperson making the connection is and need to do something extra to\nfigure it out.\n\nIf you accept this characterization of the problem, then I don't think\nthe oracle is that hard to design. We simply set it up not to allow\nwraparound connections, or maybe even more narrowly to not allow\nwraparound connections to superuser. If the DBA has some weird network\ntopology where that's not the correct rule, either because they want\nto allow wraparound connections or they want to disallow other things,\nthen yeah they have to tell us what to allow, but I don't really see\nwhy that's an unreasonable expectation. I'd expect the correct\nconfiguration of the proxy facility to fall naturally out of what's\nallowed in pg_hba.conf. If machine A is configured to accept\nconnections from machines B and C based on environmental factors, then\nmachines B and C should be configured not to proxy connections to A.\nIf machines B and C aren't under our control such that we can\nconfigure them that way, then the configuration is fundamentally\ninsecure in a way that we can't really fix.\n\nI think that what you're proposing is that B and C can just be allowed\nto proxy to A and A can say \"hey, by the way, I'm just gonna let you\nin without asking for anything else\" and B and C can, when proxying,\nreact to that by disconnecting before the connection actually goes\nthrough. That's simpler, in a sense. It doesn't require us to set up\nthe proxy configuration on B and C in a way that matches what\npg_hba.conf allows on A. Instead, B and C can automatically deduce\nwhat connections they should refuse to proxy. I guess that's nice, but\nit feels pretty magical to me. It encourages the DBA not to think\nabout what B and C should actually be allowed to proxy, and instead\njust trust that the automatics are going to prevent any security\ndisasters. I'm not sure that they always will, and I fear cultivating\ntoo much reliance on them. I think that if you're setting up a network\ntopology where the correct rule is something more complex than \"don't\nallow wraparound connections to superuser,\" maybe you ought to be\nforced to spell that rule out instead of letting the system deduce one\nthat you hope will be right.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 20 Mar 2023 12:32:00 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Wed, Mar 8, 2023 at 2:47 PM Andres Freund <andres@anarazel.de> wrote:\n> Hm - it still feels wrong that we error out in case of failure, despite the\n> comment to the function saying:\n> * Returns NULL on error and fills the err with palloc'ed error message.\n\nI've amended the comment so that it explains why it's done that way.\n\n> Other than this, the change looks ready to me.\n\nWell, it still needed documentation changes and pg_dump changes. I've\nadded those in the attached version.\n\nIf nobody's too unhappy with the idea, I plan to commit this soon,\nboth because I think that the feature is useful, and also because I\nthink it's an important security improvement. Since replication is\ncurrently run as the subscription owner, any table owner can\ncompromise the subscription owner's account, which is really bad, but\nif the subscription owner can be a non-superuser, it's a little bit\nless bad. From a security point of view, I think the right thing to do\nand what would improve security a lot more is to run replication as\nthe table owner rather than the subscription owner. I've posted a\npatch for that at\nhttp://postgr.es/m/CA+TgmoaSCkg9ww9oppPqqs+9RVqCexYCE6Aq=UsYPfnOoDeFkw@mail.gmail.com\nand AFAICT everyone agrees with the idea, even if the patch itself\nhasn't yet attracted any code reviews. But although the two patches\nare fairly closely related, this seems to be a good idea whether that\nmoves forward or not, and that seems to be a good idea whether this\nmoves forward or not. As this one has had more review and discussion,\nmy current thought is to try to get this one committed first.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com","msg_date":"Wed, 22 Mar 2023 12:16:15 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-03-22 at 12:16 -0400, Robert Haas wrote:\n> If nobody's too unhappy with the idea, I plan to commit this soon,\n> both because I think that the feature is useful, and also because I\n> think it's an important security improvement.\n\nIs there any chance I can convince you to separate the privileges of\nusing a connection string and creating a subscription, as I\nsuggested[1] earlier?\n\nIt would be useful for dblink, and I also plan to propose CREATE\nSUBSCRIPTION ... SERVER for v17 (it was too late for 16), for which it\nwould also be useful to make the distinction.\n\nYou seemed to generally think it was a reasonable idea, but wanted to\nwait for the other patch. I think it's the right breakdown of\nprivileges even now, and I don't see a reason to give ourselves a\nheadache later trying to split up the privileges later.\n\nRegards,\n\tJeff Davis\n\n[1]\nhttps://www.postgresql.org/message-id/fa1190c117c2455f2dd968a1a09f796ccef27b29.camel@j-davis.com\n\n\n","msg_date":"Wed, 22 Mar 2023 12:53:18 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, Mar 22, 2023 at 3:53 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> Is there any chance I can convince you to separate the privileges of\n> using a connection string and creating a subscription, as I\n> suggested[1] earlier?\n\nWhat would this amount to concretely? Also adding a\npg_connection_string predefined role and requiring both that and\npg_create_subscription in all cases until your proposed changes get\nmade?\n\nIf so, I don't think that's a good idea. Maybe for some reason your\nproposed changes won't end up happening, and then we've just got a\nuseless extra thing that makes things confusing. I think that adding a\npg_connection_string privilege properly belongs to whatever patch\nmakes it possible to separate the connection string from the\nsubscription, and that we probably shouldn't add those even in\nseparate commits, let alone in separate major releases.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 23 Mar 2023 11:52:18 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, 2023-03-23 at 11:52 -0400, Robert Haas wrote:\n> What would this amount to concretely? Also adding a\n> pg_connection_string predefined role and requiring both that and\n> pg_create_subscription [to CREATE SUBSCRIPTION]\n\nYes.\n\n> If so, I don't think that's a good idea. Maybe for some reason your\n> proposed changes won't end up happening, and then we've just got a\n> useless extra thing that makes things confusing.\n\nEven if my changes don't happen, I would find it less confusing and\nmore likely that users understand what they're doing.\n\nTo most users, the consequences of allowing users to write connection\nstrings on the server are far from obvious. Even we, as developers,\nneeded to spend a lot of time discussing the nuances.\n\nSomeone merely granting the ability to CREATE SUBSCRIPTION would read\nthat page in the docs, which is dominated by the mechanics of a\nsubscription and says little about the connection string, let alone the\nsecurity nuances of using it on a server.\n\nBut if there is also a separate connection string privilege required,\nwe can document it better and they are more likely to find it and\nunderstand.\n\nBeyond that, the connection string and the mechanics of the\nsubscription are really different concepts.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Thu, 23 Mar 2023 10:41:05 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Mar 23, 2023 at 1:41 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> Even if my changes don't happen, I would find it less confusing and\n> more likely that users understand what they're doing.\n\nI respectfully but firmly disagree. I think having two predefined\nroles that are both required to create a subscription and neither of\nwhich allows you to do anything other than create a subscription is\nintrinsically confusing. I'm not willing to commit a patch that works\nlike that, and I will object if someone else wants to do so.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 23 Mar 2023 15:39:31 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wed, 2023-03-22 at 12:16 -0400, Robert Haas wrote:\n> I've posted a\n> patch for that at\n> http://postgr.es/m/CA+TgmoaSCkg9ww9oppPqqs+9RVqCexYCE6Aq=UsYPfnOoDeFkw@mail.gmail.com\n> and AFAICT everyone agrees with the idea, even if the patch itself\n> hasn't yet attracted any code reviews. But although the two patches\n> are fairly closely related, this seems to be a good idea whether that\n> moves forward or not, and that seems to be a good idea whether this\n> moves forward or not. As this one has had more review and discussion,\n> my current thought is to try to get this one committed first.\n\nThe current patch (non-superuser-subscriptions) is the most user-facing\naspect, and it seems wrong to commit it before we have the security\nmodel in a reasonable place. As you pointed out[1], it's not in a\nreasonable place now, so encouraging more use seems like a bad idea.\n\nThe other patch you posted seems like it makes a lot of progress in\nthat direction, and I think that should go in first. That was one of\nthe items I suggested previously[2], so thank you for working on that.\n\nRegards,\n\tJeff Davis\n\n\n[1]\nhttps://www.postgresql.org/message-id/CA%2BTgmoavSQVcvEW3ZgZ7a1Q-TJ-fp0%2BNt7W3D7FCawArtTCBCQ%40mail.gmail.com\n\n[2]\nhttps://www.postgresql.org/message-id/27c557b12a590067c5e00588009447bb5bb2dd42.camel@j-davis.com\n\n\n","msg_date":"Fri, 24 Mar 2023 00:17:14 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Mar 24, 2023 at 3:17 AM Jeff Davis <pgsql@j-davis.com> wrote:\n> The current patch (non-superuser-subscriptions) is the most user-facing\n> aspect, and it seems wrong to commit it before we have the security\n> model in a reasonable place. As you pointed out[1], it's not in a\n> reasonable place now, so encouraging more use seems like a bad idea.\n\nI certainly agree that the security model isn't in a reasonable place\nright now. However, I feel that:\n\n(1) adding an extra predefined role doesn't really help, because it\ndoesn't actually do anything in and of itself, it only prepares for\nfuture work, and\n\n(2) even adding the connection string security stuff that you're\nproposing doesn't really help, because (2a) connection string security\nis almost completely separate from the internal security\nconsiderations addressed in the message to which you linked, and (2b)\nin my opinion, there will be a lot of people who won't use that\nconnection string security stuff even if we had it, possibly even a\nlarge majority of people won't use it, because it responds to a\nspecific use case which I think a lot of people don't have, and\n\n(3) I don't agree either that this patch would encourage more use of\nlogical replication or that it would be bad if it did. I mean, there\ncould be someone who knows about this patch and will hesitate to\ndeploy logical replication if it doesn't get committed, or maybe\nslightly more likely, won't be able to do so if this patch doesn't get\ncommitted because they're running in a cloud environment. But probably\nnot. Cloud providers are already hacking around this problem,\nMicrosoft included. As a community, we're better off having a standard\nsolution in core than having every vendor hack it their own way. And\noutside of a cloud environment, there's not really any reason for the\nlack of this patch to make a potential user hesitate. Also, features\ngetting used is a thing that I think we should all want. If logical\nreplication is in such a bad state that we think people should be\nusing it, we should rip it out until the issues are fixed. I don't\nthink anyone would seriously propose that such a course of action is\nadvisable. So the alternative is to make it better.\n\nTo reiterate what I think the most important point here is, both Azure\nand AWS already let you do this. EDB's own cloud offering is also\ngoing to let you do this, whether this change goes in or not. But if\nthis patch gets committed, then eventually all of those vendors and\nwhatever others are out there will let you do this in the same way,\ni.e. pg_create_subscription, instead of every vendor having their own\npatch to the code that does what this patch does through some method\nthat is specific to that cloud vendor. That sort of fragmentation of\nthe ecosystem is not good for anyone, AFAICS.\n\n> The other patch you posted seems like it makes a lot of progress in\n> that direction, and I think that should go in first. That was one of\n> the items I suggested previously[2], so thank you for working on that.\n\nPerhaps you could review that work?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 24 Mar 2023 09:24:54 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Mar 24, 2023 at 9:24 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> > The other patch you posted seems like it makes a lot of progress in\n> > that direction, and I think that should go in first. That was one of\n> > the items I suggested previously[2], so thank you for working on that.\n>\n> Perhaps you could review that work?\n\nAh, you already did. Thanks.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 24 Mar 2023 10:47:08 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 3/20/23 09:32, Robert Haas wrote:\n> I think this is the root of our disagreement.\n\nAgreed.\n\n> My understanding of the\n> previous discussion is that people think that the major problem here\n> is the wraparound-to-superuser attack. That is, in general, we expect\n> that when we connect to a database over the network, we expect it to\n> do some kind of active authentication, like asking us for a password,\n> or asking us for an SSL certificate that isn't just lying around for\n> anyone to use. However, in the specific case of a local connection, we\n> have a reliable way of knowing who the remote user is without any kind\n> of active authentication, namely 'peer' authentication or perhaps even\n> 'trust' if we trust all the local users, and so we don't judge it\n> unreasonable to allow local connections without any form of active\n> authentication. There can be some scenarios where even over a network\n> we can know the identity of the person connecting with complete\n> certainty, e.g. if endpoints are locked down such that the source IP\n> address is a reliable indicator of who is initiating the connection,\n> but in general when there's a network involved you don't know who the\n> person making the connection is and need to do something extra to\n> figure it out.\n\nOkay, but this is walking back from the network example you just\ndescribed upthread. Do you still consider that in scope, or...?\n\n> If you accept this characterization of the problem,\n\nI'm not going to say yes or no just yet, because I don't understand your\nrationale for where to draw the lines.\n\nIf you just want the bare minimum thing that will solve the localhost\ncase, require_auth landed this week. Login triggers are not yet a thing,\nso `require_auth=password,md5,scram-sha-256` ensures active\nauthentication. You don't even have to disallow localhost connections,\nas far as I can tell; they'll work as intended.\n\nIf you think login triggers will get in for PG16, my bigger proposal\ncan't help in time. But if you're drawing the line at \"environmental\nHBAs are fundamentally unsafe and you shouldn't use them if you have a\nproxy,\" why can't I instead draw the line at \"login triggers are\nfundamentally unsafe and you shouldn't use them if you have a proxy\"?\n\nAnd if you want to handle the across-the-network case, too, then I don't\naccept the characterization of the problem.\n\n> then I don't think\n> the oracle is that hard to design. We simply set it up not to allow\n> wraparound connections, or maybe even more narrowly to not allow\n> wraparound connections to superuser. If the DBA has some weird network\n> topology where that's not the correct rule, either because they want\n> to allow wraparound connections or they want to disallow other things,\n> then yeah they have to tell us what to allow, but I don't really see\n> why that's an unreasonable expectation.\n\nThis seems like a security model that has been carefully gerrymandered\naround the existing implementation. My argument is that the \"weird\nnetwork topology\" isn't weird at all, and it's only dangerous because of\ndecisions we made (and can unmake).\n\nI feel pretty strongly that the design arrow needs to be pointed in the\nopposite direction. The model needs to be chosen first, to prevent us\nfrom saying, \"We defend against whatever the implementation lets us\ndefend against today. Good luck, DBAs.\"\n\n> If machines B and C aren't under our control such that we can\n> configure them that way, then the configuration is fundamentally\n> insecure in a way that we can't really fix.\n\nHere's probably our biggest point of contention. You're unlikely to\nconvince me that this is the DBA's fault.\n\nIf machines B and C aren't under our control, then our *protocol* is\nfundamentally insecure in a way that we have the ability to fix, in a\nway that's already been characterized in security literature.\n\n> I think that what you're proposing is that B and C can just be allowed\n> to proxy to A and A can say \"hey, by the way, I'm just gonna let you\n> in without asking for anything else\" and B and C can, when proxying,\n> react to that by disconnecting before the connection actually goes\n> through. That's simpler, in a sense. It doesn't require us to set up\n> the proxy configuration on B and C in a way that matches what\n> pg_hba.conf allows on A. Instead, B and C can automatically deduce\n> what connections they should refuse to proxy.\n\nRight. It's meant to take the \"localhost/wraparound connection\" out of a\nclass of special things we have to worry about, and make it completely\nboring.\n\n> I guess that's nice, but\n> it feels pretty magical to me. It encourages the DBA not to think\n> about what B and C should actually be allowed to proxy, and instead\n> just trust that the automatics are going to prevent any security\n> disasters.\n\nI agree magical behavior is dangerous, if what you think it can do\ndoesn't match up with what it can actually do. Bugs are always possible,\nand maybe I'm just not seeing a corner case yet, because I'm talking too\nmuch and not coding it -- but is this really a case where I'm\noverpromising? Or does it just feel magical because it's meant to fix\nthe root issue?\n\n(Remember, I'm not arguing against your proxy filter; I just want both.\nThey complement each other.)\n\n> I'm not sure that they always will, and I fear cultivating\n> too much reliance on them.\n\nI can't really argue against this... but I'm not really sure anyone could.\n\nMy strawman rephrasing of that is, \"we have to make the feature crappy\nenough that we can blame the DBA when things go wrong.\" And even that\nstrawman could be perfectly reasonable, in situations where the DBA\nnecessarily has more information than the machine. In this case, though,\nit seems to me that the two machines have all the information necessary\nto make a correct decision between them.\n\nThanks!\n--Jacob\n\n\n","msg_date":"Fri, 24 Mar 2023 14:47:40 -0700","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\n> I certainly agree that the security model isn't in a reasonable place\n> right now. However, I feel that:\n> \n> (1) adding an extra predefined role\n\n> (2) even adding the connection string security stuff\n\nI don't see how these points are related to the question of whether you\nshould commit your non-superuser-subscription-owners patch or logical-\nrepl-as-table-owner patch first.\n\n\nMy perspective is that logical replication is an unfinished feature\nwith an incomplete design. As I said earlier, that's why I backed away\nfrom trying to do non-superuser subscriptions as a documented feature:\nit feels like we need to settle some of the underlying pieces first.\n\nThere are some big issues, like the security model for replaying\nchanges. And some smaller issues like feature gaps (RLS doesn't work,\nif I remember correctly, and maybe something with partitioning). There\nare potential clashes with other proposals, like the CREATE\nSUBSCRIPTION ... SERVER, which I hope can be sorted out later. And I\ndon't feel like I have a good handle on the publisher security model\nand threats, which hopefully is just a matter of documenting some best\npractices.\n\nEach time we dig into one of these issues I learn something, and I\nthink others do, too. If we skip past that process and start adding new\nfeatures on top of this unfinished design, then I think we are setting\nourselves up for trouble that is going to be harder to fix later.\n\nI don't mean to say all of the above issues are blockers or that they\nshould all be resolved in my favor. But there are enough issues and\nsome of those issues are serious enough that I feel like it's premature\nto just go ahead with the non-superuser subscriptions and the\npredefined role.\n\nThere are already users, which complicates things. And you make a good\npoint that some important users may be already working around the\nflaws. But there's already a patch and discussion going on for some\nsecurity model improvements (thanks to you), so let's try to get that\none in first. If we can't, it's probably because we learned something\nimportant.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Sat, 25 Mar 2023 12:16:35 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi,\n\nOn 2023-03-25 12:16:35 -0700, Jeff Davis wrote:\n> On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\n> > I certainly agree that the security model isn't in a reasonable place\n> > right now. However, I feel that:\n> > \n> > (1) adding an extra predefined role\n> \n> > (2) even adding the connection string security stuff\n> \n> I don't see how these points are related to the question of whether you\n> should commit your non-superuser-subscription-owners patch or logical-\n> repl-as-table-owner patch first.\n> \n> \n> My perspective is that logical replication is an unfinished feature\n> with an incomplete design.\n\nI agree with that much.\n\n\n> �As I said earlier, that's why I backed away from trying to do non-superuser\n> subscriptions as a documented feature: it feels like we need to settle some\n> of the underlying pieces first.\n\nI don't agree. The patch allows to use logical rep in a far less dangerous\nfashion than now. The alternative is to release 16 without a real way to use\nlogical rep less insanely. Which I think is work.\n\n\n> There are some big issues, like the security model for replaying\n> changes.\n\nThat seems largely unrelated.\n\n\n> And some smaller issues like feature gaps (RLS doesn't work,\n> if I remember correctly, and maybe something with partitioning).\n\nEntirely unrelated?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 27 Mar 2023 10:46:38 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Mar 25, 2023 at 3:16 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\n> > I certainly agree that the security model isn't in a reasonable place\n> > right now. However, I feel that:\n> >\n> > (1) adding an extra predefined role\n>\n> > (2) even adding the connection string security stuff\n>\n> I don't see how these points are related to the question of whether you\n> should commit your non-superuser-subscription-owners patch or logical-\n> repl-as-table-owner patch first.\n\nI thought you were asking for those changes to be made before this\npatch got committed, so that's what I was responding to. If you're\nasking for it not to be committed at all, that's a different\ndiscussion.\n\n> My perspective is that logical replication is an unfinished feature\n> with an incomplete design. As I said earlier, that's why I backed away\n> from trying to do non-superuser subscriptions as a documented feature:\n> it feels like we need to settle some of the underlying pieces first.\n\nI kind of agree with you about the feature itself. Even though the\nbasic feature works quite well and does something people really want,\nthere are a lot of loose ends to sort out, and not just about\nsecurity. But I also want to make some progress. If there are problems\nwith what I'm proposing that will make us regret committing things\nright before feature freeze, then we shouldn't. But waiting a whole\nadditional year to see any kind of improvement is not free; these\nissues are serious.\n\n> I don't mean to say all of the above issues are blockers or that they\n> should all be resolved in my favor. But there are enough issues and\n> some of those issues are serious enough that I feel like it's premature\n> to just go ahead with the non-superuser subscriptions and the\n> predefined role.\n>\n> There are already users, which complicates things. And you make a good\n> point that some important users may be already working around the\n> flaws. But there's already a patch and discussion going on for some\n> security model improvements (thanks to you), so let's try to get that\n> one in first. If we can't, it's probably because we learned something\n> important.\n\nI think this patch is a lot better-baked and less speculative than\nthat one. I think that patch is more important, so if they were\nequally mature, I'd favor getting that one committed first. But that's\nnot the case.\n\nAlso, I don't really understand how we could end up not wanting this\npatch. I mean there's a lot of things I don't understand that are\nstill true anyway, so the mere fact that I don't understand how we\ncould not end up wanting this patch doesn't mean that it couldn't\nhappen. But like, the current state of play is that subscription\nowners are always going to be superusers at the time the subscription\nis created, and literally nobody thinks that's a good idea. Some\npeople (like me) think that we ought to assume that subscription\nowners will be and need to be high-privilege users like superusers,\nbut to my knowledge every such person thinks that it's OK for the\nsubscription owner to be a non-superuser if they have adequate\nprivileges. I just think that's a high amount of privileges, not that\nit has to be all the privileges i.e. superuser. Other people (like\nyou, AIUI) think that we ought to try to set things up so that\nsubscription owners can be low-privilege users, in which case we, once\nagain, don't want the user who owns the subscription to start out a\nsuperuser. I actually can't imagine anyone defending the idea of\nhaving the subscription owner always be a superuser at the time they\nfirst own the subscription. That's a weird rule that can only serve to\nreduce security. Nor can I imagine anyone saying that forcing\nsubscriptions to be created only by superusers improves security. I\ndon't think anyone thinks that.\n\nIf we're going to delay this patch, probably for a full year, because\nof other ongoing discussions, it should be because there is some\noutcome of those discussions that would involve deciding that this\npatch isn't needed or should be significantly redesigned. If this\npatch is going to end up being desirable no matter how those\ndiscussions turn out, and if it's not going to change significantly no\nmatter how those discussions turn out, then those discussions aren't a\nreason not to get it into this release.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 27 Mar 2023 14:06:45 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2023-03-27 at 10:46 -0700, Andres Freund wrote:\n> > There are some big issues, like the security model for replaying\n> > changes.\n> \n> That seems largely unrelated.\n\nThey are self-evidently related in a fundamental way. The behavior of\nthe non-superuser-subscription patch depends on the presence of the\napply-as-table-owner patch.\n\nI think I'd like to understand the apply-as-table-owner patch better to\nunderstand the interaction.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Mon, 27 Mar 2023 12:21:15 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, 2023-03-27 at 14:06 -0400, Robert Haas wrote:\n> I thought you were asking for those changes to be made before this\n> patch got committed, so that's what I was responding to. If you're\n> asking for it not to be committed at all, that's a different\n> discussion.\n\nI separately had a complaint (in a separate subthread) about the scope\nof the predefined role you are introducing, which I think encompasses\ntwo concepts that should be treated differently and I think that may\nneed to be revisited later. If you ignore this complaint it wouldn't be\nthe end of the world.\n\nThis subthread is about the order in which the patches get committed\n(which is a topic you brought up), not whether they are ever to be\ncommitted.\n\n> \n> I kind of agree with you about the feature itself. Even though the\n> basic feature works quite well and does something people really want,\n> there are a lot of loose ends to sort out, and not just about\n> security. But I also want to make some progress. If there are\n> problems\n> with what I'm proposing that will make us regret committing things\n> right before feature freeze, then we shouldn't. But waiting a whole\n> additional year to see any kind of improvement is not free; these\n> issues are serious.\n\nThe non-superuser-subscription-owner patch without the apply-as-table-\nowner patch feels like a facade to me, at least right now. Perhaps I\ncan be convinced otherwise, but that's what it looks like to me.\n\n> \n> I think this patch is a lot better-baked and less speculative than\n> that one. I think that patch is more important, so if they were\n> equally mature, I'd favor getting that one committed first. But\n> that's\n> not the case.\n\nYou explicitly asked about the order of the patches, which made me\nthink it was more of an option?\n\nIf the apply-as-table-owner patch gets held up for whatever reason, we\nmight have to make a difficult decision. I'd prefer focus on the apply-\nas-table-owner patch briefly, and now that it's getting some review\nattention, we might find out how ready it is quite soon.\n\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Mon, 27 Mar 2023 15:17:27 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\n> The other patch you posted seems like it makes a lot of progress in\n> that direction, and I think that should go in first. That was one of\n> the items I suggested previously[2], so thank you for working on\n> that.\n\nThe above is not a hard objection.\n\nI still hold the opinion that the non-superuser subscriptions work is\nfeels premature without the apply-as-table-owner work. It would be\ngreat if the other patch ends up ready quickly, which would moot the\ncommit-ordering question.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Tue, 28 Mar 2023 10:52:33 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Mar 24, 2023 at 5:47 PM Jacob Champion <jchampion@timescale.com> wrote:\n> Okay, but this is walking back from the network example you just\n> described upthread. Do you still consider that in scope, or...?\n\nSorry, I don't know which example you mean.\n\n> > If machines B and C aren't under our control such that we can\n> > configure them that way, then the configuration is fundamentally\n> > insecure in a way that we can't really fix.\n>\n> Here's probably our biggest point of contention. You're unlikely to\n> convince me that this is the DBA's fault.\n>\n> If machines B and C aren't under our control, then our *protocol* is\n> fundamentally insecure in a way that we have the ability to fix, in a\n> way that's already been characterized in security literature.\n\nI guess I wouldn't have a problem blaming the DBA here, but you seem\nto be telling me that the security literature has settled on another\nkind of approach, and I'm not in a position to dispute that. It still\nfeels weird to me, though.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 30 Mar 2023 08:58:20 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\n> > The other patch you posted seems like it makes a lot of progress in\n> > that direction, and I think that should go in first. That was one of\n> > the items I suggested previously[2], so thank you for working on\n> > that.\n>\n> The above is not a hard objection.\n\nThe other patch is starting to go in a direction that is going to have\nsome conflicts with this one, so I went ahead and committed this one\nto avoid rebasing pain.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 30 Mar 2023 12:04:51 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Greetings,\n\n* Jacob Champion (jchampion@timescale.com) wrote:\n> On 3/20/23 09:32, Robert Haas wrote:\n> > I think this is the root of our disagreement.\n> \n> Agreed.\n\nI've read all the way back to the $SUBJECT change to try and get an\nunderstanding of the questions here and it's not been easy, in part, I\nthink, due to the verbiage but also the perhaps lack of concrete\nexamples and instead references to other systems and protocols.\n\n> > My understanding of the\n> > previous discussion is that people think that the major problem here\n> > is the wraparound-to-superuser attack. That is, in general, we expect\n> > that when we connect to a database over the network, we expect it to\n> > do some kind of active authentication, like asking us for a password,\n> > or asking us for an SSL certificate that isn't just lying around for\n> > anyone to use. However, in the specific case of a local connection, we\n> > have a reliable way of knowing who the remote user is without any kind\n> > of active authentication, namely 'peer' authentication or perhaps even\n> > 'trust' if we trust all the local users, and so we don't judge it\n> > unreasonable to allow local connections without any form of active\n> > authentication. There can be some scenarios where even over a network\n> > we can know the identity of the person connecting with complete\n> > certainty, e.g. if endpoints are locked down such that the source IP\n> > address is a reliable indicator of who is initiating the connection,\n> > but in general when there's a network involved you don't know who the\n> > person making the connection is and need to do something extra to\n> > figure it out.\n> \n> Okay, but this is walking back from the network example you just\n> described upthread. Do you still consider that in scope, or...?\n\nThe concern around the network certainly needs to be in-scope overall.\n\n> > If you accept this characterization of the problem,\n> \n> I'm not going to say yes or no just yet, because I don't understand your\n> rationale for where to draw the lines.\n> \n> If you just want the bare minimum thing that will solve the localhost\n> case, require_auth landed this week. Login triggers are not yet a thing,\n> so `require_auth=password,md5,scram-sha-256` ensures active\n> authentication. You don't even have to disallow localhost connections,\n> as far as I can tell; they'll work as intended.\n\nI do think require_auth helps us move in a positive direction. As I\nmentioned elsewhere, I don't think we highlight it nearly enough in the\npostgres_fdw documentation. Let's look at that in a bit more depth with\nconcrete examples and perhaps everyone will be able to get a bit more\nunderstanding of the issues.\n\nClient is psql\nProxy is some PG server that's got postgres_fdw\nTarget is another PG server, that is being connected to from Proxy\nAuthentication is via GSS/Kerberos with proxied credentials\n\nWhat do we want to require the user to configure to make this secure?\n\nProxy's pg_hba configured to require GSS auth from Client.\nTarget's pg_hba configured to require GSS auth from Proxy.\n\nWho are we trusting with what? In particular, I'd argue that the user\nwho is able to install the postgres_fdw extension and the user who is\nable to issue the CREATE SERVER are largely trusted; at least in so far\nas the user doing CREATE SERVER is allowed to create the server and\nthrough that allowed to make outbound connections from the Proxy.\n\nTherefore, the Proxy is configured with postgres_fdw and with a trusted\nuser performing the CREATE SERVER.\n\nWhat doesn't this handle today? Connection side-effects are one\nproblem- once the CREATE SERVER is done, any user with USAGE rights on\nthe server can create a USER MAPPING for themselves, either with a\npassword or without one (if they're able to proxy GSS credentials to the\nsystem). They aren't able to set password_required though, which\ndefaults to true. However, without having require_auth set, they're\nable to cause the Proxy to reach an authentication stage with the Target\nthat might not match what credentials they're supposed to be providing.\n\nWe attempt to address this by checking post-auth to Target that we used\nthe credentials to connect that we expected to- if GSS credentials were\nproxied, then we expect to use those. If a password was provided then\nwe expect to use a password to auth (only checked after we see if GSS\ncredentials were proxied and used). The issue here is 'post-auth' bit,\nwe'd prefer to fail the connection pre-auth if it isn't what we're\nexpecting. Should we then explicit set require_auth=gss when GSS\ncredentials are proxied? Also, if a password is provided, then\nexplicitly set require_auth=scram-sha-256? Or default to these, at\nleast, and allow the CREATE SERVER user to override our choices? Or\nshould it be a USER MAPPING option that's restricted? Or not?\n\n> > I think that what you're proposing is that B and C can just be allowed\n> > to proxy to A and A can say \"hey, by the way, I'm just gonna let you\n> > in without asking for anything else\" and B and C can, when proxying,\n> > react to that by disconnecting before the connection actually goes\n> > through. That's simpler, in a sense. It doesn't require us to set up\n> > the proxy configuration on B and C in a way that matches what\n> > pg_hba.conf allows on A. Instead, B and C can automatically deduce\n> > what connections they should refuse to proxy.\n> \n> Right. It's meant to take the \"localhost/wraparound connection\" out of a\n> class of special things we have to worry about, and make it completely\n> boring.\n\nAgain, trying to get at a more concrete example- the concern here is a\nuser with CREATE SERVER ability could leverage that access to become a\nsuperuser if the system is configured with 'peer' access, right? A\nnon-superuser is already prevented from being able to set\n\"password_required=false\", perhaps we shouldn't allow them to set\n\"require_auth=none\" (or have that effect) either? Perhaps the system\nshould simply forcibly set require_auth based on the credentials\nprovided in the USER MAPPING or on the connection and have require_auth\notherwise restricted to superuser (who could override it if they'd\nreally like to)? Perhaps if password_required=false we implicitly\nun-set require_auth, to avoid having to make superusers change their\nexisting configurations where they've clearly already accepted that\ncredential-less connections are allowed.\n\nAutomatically setting require_auth and restricting the ability of it to\nbe set on user mappings to superusers doesn't strike me as terribly\ndifficult to do and seems like it'd prevent this concern.\n\nJust to make sure I'm following- Robert's up-thread suggestion of an\n'outbound pg_hba' would be an additional restriction when it comes to\nwhat a user who can use CREATE SERVER is allowed to do? I'm not against\nthe idea of having a way to lock that down.. but it's another level of\ncomplication certainly and I'm not sure that some external config file\nor such is the best way to try and deal with that, though I do see how\nit can have some appeal for certain environments. It does overall\nstrike me as something we've not tried to address in any way thus far\nand a pretty large effort that's not likely to make it into PG16, unlike\nthe possibility of auto-setting require_auth, now that it exists.\n\nThanks!\n\nStephen","msg_date":"Thu, 30 Mar 2023 14:13:51 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Friday, March 31, 2023 12:05 AM Robert Haas <robertmhaas@gmail.com> wrote:\r\n\r\nHi,\r\n\r\n> \r\n> On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\r\n> > On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\r\n> > > The other patch you posted seems like it makes a lot of progress in\r\n> > > that direction, and I think that should go in first. That was one of\r\n> > > the items I suggested previously[2], so thank you for working on\r\n> > > that.\r\n> >\r\n> > The above is not a hard objection.\r\n> \r\n> The other patch is starting to go in a direction that is going to have some\r\n> conflicts with this one, so I went ahead and committed this one to avoid\r\n> rebasing pain.\r\n\r\nI noticed the BF[1] report a core dump after this commit.\r\n\r\n#0 0xfd581864 in _lwp_kill () from /usr/lib/libc.so.12\r\n#0 0xfd581864 in _lwp_kill () from /usr/lib/libc.so.12\r\n#1 0xfd5817dc in raise () from /usr/lib/libc.so.12\r\n#2 0xfd581c88 in abort () from /usr/lib/libc.so.12\r\n#3 0x01e6c8d4 in ExceptionalCondition (conditionName=conditionName@entry=0x2007758 \"IsTransactionState()\", fileName=fileName@entry=0x20565c4 \"catcache.c\", lineNumber=lineNumber@entry=1208) at assert.c:66\r\n#4 0x01e4e404 in SearchCatCacheInternal (cache=0xfd21e500, nkeys=nkeys@entry=1, v1=v1@entry=28985, v2=v2@entry=0, v3=v3@entry=0, v4=v4@entry=0) at catcache.c:1208\r\n#5 0x01e4eea0 in SearchCatCache1 (cache=<optimized out>, v1=v1@entry=28985) at catcache.c:1162\r\n#6 0x01e66e34 in SearchSysCache1 (cacheId=cacheId@entry=11, key1=key1@entry=28985) at syscache.c:825\r\n#7 0x01e98c40 in superuser_arg (roleid=28985) at superuser.c:70\r\n#8 0x01c657bc in ApplyWorkerMain (main_arg=<optimized out>) at worker.c:4552\r\n#9 0x01c1ceac in StartBackgroundWorker () at bgworker.c:861\r\n#10 0x01c23be0 in do_start_bgworker (rw=<optimized out>) at postmaster.c:5762\r\n#11 maybe_start_bgworkers () at postmaster.c:5986\r\n#12 0x01c2459c in process_pm_pmsignal () at postmaster.c:5149\r\n#13 ServerLoop () at postmaster.c:1770\r\n#14 0x01c26cdc in PostmasterMain (argc=argc@entry=4, argv=argv@entry=0xffffe0e4) at postmaster.c:1463\r\n#15 0x01ee2c8c in main (argc=4, argv=0xffffe0e4) at main.c:200\r\n\r\nIt looks like the super user check is out of a transaction, I haven't checked why\r\nit only failed on one BF animal, but it seems we can put the check into the\r\ntransaction like the following:\r\n\r\ndiff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c\r\nindex 6fd674b5d6..08f10fc331 100644\r\n--- a/src/backend/replication/logical/worker.c\r\n+++ b/src/backend/replication/logical/worker.c\r\n@@ -4545,12 +4545,13 @@ ApplyWorkerMain(Datum main_arg)\r\n \t\treplorigin_session_setup(originid, 0);\r\n \t\treplorigin_session_origin = originid;\r\n \t\torigin_startpos = replorigin_session_get_progress(false);\r\n-\t\tCommitTransactionCommand();\r\n \r\n \t\t/* Is the use of a password mandatory? */\r\n \t\tmust_use_password = MySubscription->passwordrequired &&\r\n \t\t\t!superuser_arg(MySubscription->owner);\r\n \r\n+\t\tCommitTransactionCommand();\r\n+\r\n\r\n[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2023-03-30%2019%3A41%3A08\r\n\r\nBest Regards,\r\nHou Zhijie\r\n","msg_date":"Fri, 31 Mar 2023 01:49:28 +0000","msg_from":"\"houzj.fnst@fujitsu.com\" <houzj.fnst@fujitsu.com>","msg_from_op":false,"msg_subject":"RE: Non-superuser subscription owners"},{"msg_contents":"On Thu, Mar 30, 2023 at 9:49 PM houzj.fnst@fujitsu.com\n<houzj.fnst@fujitsu.com> wrote:\n> It looks like the super user check is out of a transaction, I haven't checked why\n> it only failed on one BF animal, but it seems we can put the check into the\n> transaction like the following:\n\nThat looks like a reasonable fix but I can't reproduce the problem\nlocally. I thought the reason why that machine sees the problem might\nbe that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\nand the tests still pass. Anyone ideas how to reproduce?\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 31 Mar 2023 16:00:08 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Saturday, April 1, 2023 4:00 AM Robert Haas <robertmhaas@gmail.com>\r\n\r\nHi,\r\n\r\n> \r\n> On Thu, Mar 30, 2023 at 9:49 PM houzj.fnst@fujitsu.com\r\n> <houzj.fnst@fujitsu.com> wrote:\r\n> > It looks like the super user check is out of a transaction, I haven't\r\n> > checked why it only failed on one BF animal, but it seems we can put\r\n> > the check into the transaction like the following:\r\n> \r\n> That looks like a reasonable fix but I can't reproduce the problem locally. I\r\n> thought the reason why that machine sees the problem might be that it uses\r\n> -DRELCACHE_FORCE_RELEASE, but I tried that option here and the tests still pass.\r\n> Anyone ideas how to reproduce?\r\n\r\nI think it's a timing problem because superuser_arg() function will cache the\r\nroleid that passed in last time, so it might not search the syscache to hit the\r\nAssert() check each time. And in the regression test, the roleid cache happened\r\nto be invalidated before the superuser_arg() by some concurrently ROLE change(\r\nmaybe in subscription.sql and publication.sql).\r\n\r\nI can reproduce it by using gdb and starting another session to change the ROLE.\r\n\r\nWhen the apply worker starts, use the gdb to block the apply worker in the\r\ntransaction before the super user check. Then start another session to ALTER\r\nROLE to invalidate the roleid cache in superuser_arg() which will cause the\r\napply worker to search the syscache and hit the Assert().\r\n\r\n--\r\n\t\torigin_startpos = replorigin_session_get_progress(false);\r\nB*\t\tCommitTransactionCommand();\r\n\r\n\t\t/* Is the use of a password mandatory? */\r\n\t\tmust_use_password = MySubscription->passwordrequired &&\r\n\t\t\t! superuser_arg(MySubscription->owner);\r\n--\r\n\r\nBest Regards,\r\nHou zj\r\n","msg_date":"Sat, 1 Apr 2023 01:24:05 +0000","msg_from":"\"houzj.fnst@fujitsu.com\" <houzj.fnst@fujitsu.com>","msg_from_op":false,"msg_subject":"RE: Non-superuser subscription owners"},{"msg_contents":"Hello Robert,\n\n31.03.2023 23:00, Robert Haas wrote:\n> That looks like a reasonable fix but I can't reproduce the problem\n> locally. I thought the reason why that machine sees the problem might\n> be that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\n> and the tests still pass. Anyone ideas how to reproduce?\n\nI've managed to reproduce it using the following script:\nfor ((i=1;i<=10;i++)); do\necho \"iteration $i\"\necho \"\nCREATE ROLE sub_user;\nCREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\n PUBLICATION testpub WITH (connect = false);\nALTER SUBSCRIPTION testsub ENABLE;\nDROP SUBSCRIPTION testsub;\nSELECT pg_sleep(0.001);\nDROP ROLE sub_user;\n\" | psql\npsql -c \"ALTER SUBSCRIPTION testsub DISABLE;\"\npsql -c \"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\"\npsql -c \"DROP SUBSCRIPTION testsub;\"\ngrep 'TRAP' server.log && break\ndone\n\niteration 3\nCREATE ROLE\n...\nALTER SUBSCRIPTION\nWARNING: terminating connection because of crash of another server process\nDETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because ano\nther server process exited abnormally and possibly corrupted shared memory.\nHINT: In a moment you should be able to reconnect to the database and repeat your command.\nserver closed the connection unexpectedly\n This probably means the server terminated abnormally\n before or while processing the request.\nconnection to server was lost\nTRAP: failed Assert(\"IsTransactionState()\"), File: \"catcache.c\", Line: 1208, PID: 1001242\n\nBest regards,\nAlexander\n\n\n\n\n\nHello Robert,\n\n 31.03.2023 23:00, Robert Haas wrote:\n\n\nThat looks like a reasonable fix but I can't reproduce the problem\nlocally. I thought the reason why that machine sees the problem might\nbe that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\nand the tests still pass. Anyone ideas how to reproduce?\n\n\n\n I've managed to reproduce it using the following script:\n for ((i=1;i<=10;i++)); do\n echo \"iteration $i\"\n echo \"\n CREATE ROLE sub_user;\n CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\n PUBLICATION testpub WITH (connect = false);\n ALTER SUBSCRIPTION testsub ENABLE;\n DROP SUBSCRIPTION testsub;\n SELECT pg_sleep(0.001);\n DROP ROLE sub_user;\n \" | psql\n psql -c \"ALTER SUBSCRIPTION testsub DISABLE;\"\n psql -c \"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\"\n psql -c \"DROP SUBSCRIPTION testsub;\"\n grep 'TRAP' server.log && break\n done\n\niteration 3\n \n CREATE ROLE\n \n ...\n ALTER SUBSCRIPTION\n \n WARNING: terminating connection because of crash of another\n server process\n \n DETAIL: The postmaster has commanded this server process to roll\n back the current transaction and exit, because ano\n ther server process exited abnormally and possibly corrupted\n shared memory.\n \n HINT: In a moment you should be able to reconnect to the database\n and repeat your command.\n \n server closed the connection unexpectedly\n \n This probably means the server terminated abnormally\n \n before or while processing the request.\n \n connection to server was lost\n \n TRAP: failed Assert(\"IsTransactionState()\"), File: \"catcache.c\",\n Line: 1208, PID: 1001242\n\nBest regards,\n Alexander","msg_date":"Sat, 1 Apr 2023 19:00:00 +0300","msg_from":"Alexander Lakhin <exclusion@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"Hi, \n\nOn April 1, 2023 9:00:00 AM PDT, Alexander Lakhin <exclusion@gmail.com> wrote:\n>Hello Robert,\n>\n>31.03.2023 23:00, Robert Haas wrote:\n>> That looks like a reasonable fix but I can't reproduce the problem\n>> locally. I thought the reason why that machine sees the problem might\n>> be that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\n>> and the tests still pass. Anyone ideas how to reproduce?\n>\n>I've managed to reproduce it using the following script:\n>for ((i=1;i<=10;i++)); do\n>echo \"iteration $i\"\n>echo \"\n>CREATE ROLE sub_user;\n>CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\n> PUBLICATION testpub WITH (connect = false);\n>ALTER SUBSCRIPTION testsub ENABLE;\n>DROP SUBSCRIPTION testsub;\n>SELECT pg_sleep(0.001);\n>DROP ROLE sub_user;\n>\" | psql\n>psql -c \"ALTER SUBSCRIPTION testsub DISABLE;\"\n>psql -c \"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\"\n>psql -c \"DROP SUBSCRIPTION testsub;\"\n>grep 'TRAP' server.log && break\n>done\n>\n>iteration 3\n>CREATE ROLE\n>...\n>ALTER SUBSCRIPTION\n>WARNING: terminating connection because of crash of another server process\n>DETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because ano\n>ther server process exited abnormally and possibly corrupted shared memory.\n>HINT: In a moment you should be able to reconnect to the database and repeat your command.\n>server closed the connection unexpectedly\n> This probably means the server terminated abnormally\n> before or while processing the request.\n>connection to server was lost\n>TRAP: failed Assert(\"IsTransactionState()\"), File: \"catcache.c\", Line: 1208, PID: 1001242\n\nErrors like that are often easier to reproduce with clobber caches (or whatever the name is these days) enabled.\n\nAndres\n-- \nSent from my Android device with K-9 Mail. Please excuse my brevity.\n\n\n","msg_date":"Sat, 01 Apr 2023 16:07:14 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Apr 1, 2023 at 12:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:\n> I've managed to reproduce it using the following script:\n> for ((i=1;i<=10;i++)); do\n> echo \"iteration $i\"\n> echo \"\n> CREATE ROLE sub_user;\n> CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\n> PUBLICATION testpub WITH (connect = false);\n> ALTER SUBSCRIPTION testsub ENABLE;\n> DROP SUBSCRIPTION testsub;\n> SELECT pg_sleep(0.001);\n> DROP ROLE sub_user;\n> \" | psql\n> psql -c \"ALTER SUBSCRIPTION testsub DISABLE;\"\n> psql -c \"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\"\n> psql -c \"DROP SUBSCRIPTION testsub;\"\n> grep 'TRAP' server.log && break\n> done\n\nAfter a bit of experimentation this repro worked for me -- I needed\n-DRELCACHE_FORCE_RELEASE as well, and a bigger iteration count. I\nverified that the patch fixed it, and committed the patch with the\naddition of a comment.\n\nThanks very much for this repro, and likewise many thanks to Hou\nZhijie for the report and patch.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 3 Apr 2023 13:56:31 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Mar 30, 2023 at 9:35 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\n> > > The other patch you posted seems like it makes a lot of progress in\n> > > that direction, and I think that should go in first. That was one of\n> > > the items I suggested previously[2], so thank you for working on\n> > > that.\n> >\n> > The above is not a hard objection.\n>\n> The other patch is starting to go in a direction that is going to have\n> some conflicts with this one, so I went ahead and committed this one\n> to avoid rebasing pain.\n>\n\nDo we need to have a check for this new option \"password_required\" in\nmaybe_reread_subscription() where we \"Exit if any parameter that\naffects the remote connection was changed.\"? This new option is\nrelated to the remote connection so I thought it is worth considering\nwhether we want to exit and restart the apply worker when this option\nis changed.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Sat, 8 Apr 2023 11:04:53 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Sat, Apr 8, 2023 at 1:35 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> Do we need to have a check for this new option \"password_required\" in\n> maybe_reread_subscription() where we \"Exit if any parameter that\n> affects the remote connection was changed.\"? This new option is\n> related to the remote connection so I thought it is worth considering\n> whether we want to exit and restart the apply worker when this option\n> is changed.\n\nHmm, good question. I think that's probably a good idea. If the\ncurrent connection is already working, the only possible result of\ngetting rid of it and trying to create a new one is that it might now\nfail instead, but someone might want that behavior. Otherwise, they'd\ninstead find the failure at a later, maybe less convenient, time.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 10 Apr 2023 11:45:11 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Apr 10, 2023 at 9:15 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Sat, Apr 8, 2023 at 1:35 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > Do we need to have a check for this new option \"password_required\" in\n> > maybe_reread_subscription() where we \"Exit if any parameter that\n> > affects the remote connection was changed.\"? This new option is\n> > related to the remote connection so I thought it is worth considering\n> > whether we want to exit and restart the apply worker when this option\n> > is changed.\n>\n> Hmm, good question. I think that's probably a good idea. If the\n> current connection is already working, the only possible result of\n> getting rid of it and trying to create a new one is that it might now\n> fail instead, but someone might want that behavior. Otherwise, they'd\n> instead find the failure at a later, maybe less convenient, time.\n>\n\nI think additionally, we should check that the new owner of the\nsubscription is not a superuser, otherwise, anyway, this parameter is\nignored. Please find the attached to add this check.\n\n-- \nWith Regards,\nAmit Kapila.","msg_date":"Tue, 11 Apr 2023 15:23:18 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Apr 11, 2023 at 5:53 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> I think additionally, we should check that the new owner of the\n> subscription is not a superuser, otherwise, anyway, this parameter is\n> ignored. Please find the attached to add this check.\n\nI don't see why we should check that. It makes this different from all\nthe other cases and I don't see any benefit.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 11 Apr 2023 10:51:39 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Apr 11, 2023 at 8:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Tue, Apr 11, 2023 at 5:53 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > I think additionally, we should check that the new owner of the\n> > subscription is not a superuser, otherwise, anyway, this parameter is\n> > ignored. Please find the attached to add this check.\n>\n> I don't see why we should check that. It makes this different from all\n> the other cases and I don't see any benefit.\n>\n\nI thought it would be better if we don't restart the worker unless it\nis required. In case, the subscription's owner is a superuser, the\n'password_required' is ignored, so why restart the apply worker when\nsomebody changes it in such a case? I understand that there may not be\na need to change the 'password_required' option when the\nsubscription's owner is the superuser but one may first choose to\nchange the password_required flag and then the owner of a subscription\nto a non-superuser. Anyway, I don't think as such there is any problem\nwith restarting the worker even when the subscription owner is a\nsuperuser, so adjusted the check accordingly.\n\n-- \nWith Regards,\nAmit Kapila.","msg_date":"Wed, 12 Apr 2023 08:26:02 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> Anyway, I don't think as such there is any problem\n> with restarting the worker even when the subscription owner is a\n> superuser, so adjusted the check accordingly.\n\nLGTM. I realize we could do more sophisticated things here, but I\nthink it's better to keep the code simple.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 12 Apr 2023 08:19:51 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On 3/30/23 05:58, Robert Haas wrote:\n> On Fri, Mar 24, 2023 at 5:47 PM Jacob Champion <jchampion@timescale.com> wrote:\n>> Okay, but this is walking back from the network example you just\n>> described upthread. Do you still consider that in scope, or...?\n> \n> Sorry, I don't know which example you mean.\n\nThe symmetrical proxy situation you described, where all the proxies are\nmutually trusting. While it's easier to secure that setup than the\nasymmetrical ones, it's also not a localhost-only situation anymore, and\nthe moment you open up to other machines is where I think your\ncharacterization runs into trouble.\n\n> I guess I wouldn't have a problem blaming the DBA here, but you seem\n> to be telling me that the security literature has settled on another\n> kind of approach, and I'm not in a position to dispute that. It still\n> feels weird to me, though.\n\nIf it helps, [1] is a paper that helped me wrap my head around some of\nit. It's focused on capability systems and an academic audience, but the\n\"Avoiding Confused Deputy Problems\" section starting on page 11 is a\ngood place to jump to for the purposes of this discussion.\n\n--Jacob\n\n[1] https://srl.cs.jhu.edu/pubs/SRL2003-02.pdf\n\n\n","msg_date":"Wed, 12 Apr 2023 11:23:01 -0700","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On 3/30/23 11:13, Stephen Frost wrote:\n>> Okay, but this is walking back from the network example you just\n>> described upthread. Do you still consider that in scope, or...?\n> \n> The concern around the network certainly needs to be in-scope overall.\n\nSounds good!\n\n> Who are we trusting with what? In particular, I'd argue that the user\n> who is able to install the postgres_fdw extension and the user who is\n> able to issue the CREATE SERVER are largely trusted; at least in so far\n> as the user doing CREATE SERVER is allowed to create the server and\n> through that allowed to make outbound connections from the Proxy.\n> \n> Therefore, the Proxy is configured with postgres_fdw and with a trusted\n> user performing the CREATE SERVER.\n> \n> What doesn't this handle today? Connection side-effects are one\n> problem- once the CREATE SERVER is done, any user with USAGE rights on\n> the server can create a USER MAPPING for themselves, either with a\n> password or without one (if they're able to proxy GSS credentials to the\n> system). They aren't able to set password_required though, which\n> defaults to true. However, without having require_auth set, they're\n> able to cause the Proxy to reach an authentication stage with the Target\n> that might not match what credentials they're supposed to be providing.\n> \n> We attempt to address this by checking post-auth to Target that we used\n> the credentials to connect that we expected to- if GSS credentials were\n> proxied, then we expect to use those. If a password was provided then\n> we expect to use a password to auth (only checked after we see if GSS\n> credentials were proxied and used). The issue here is 'post-auth' bit,\n> we'd prefer to fail the connection pre-auth if it isn't what we're\n> expecting.\n\nRight. Keep in mind that require_auth is post-auth, though; it can't fix\nthat issue, so it doesn't fix any connection side-effect problems at all.\n\n> Should we then explicit set require_auth=gss when GSS\n> credentials are proxied? Also, if a password is provided, then\n> explicitly set require_auth=scram-sha-256? Or default to these, at\n> least, and allow the CREATE SERVER user to override our choices? Or\n> should it be a USER MAPPING option that's restricted? Or not?\nIMO, yes -- whatever credentials the proxy is forwarding from the user,\nthe proxy should be checking that the server has actually used them. The\nperson with the ability to create a USER MAPPING should probably not\nhave the ability to override that check.\n\n>>> I think that what you're proposing is that B and C can just be allowed\n>>> to proxy to A and A can say \"hey, by the way, I'm just gonna let you\n>>> in without asking for anything else\" and B and C can, when proxying,\n>>> react to that by disconnecting before the connection actually goes\n>>> through. That's simpler, in a sense. It doesn't require us to set up\n>>> the proxy configuration on B and C in a way that matches what\n>>> pg_hba.conf allows on A. Instead, B and C can automatically deduce\n>>> what connections they should refuse to proxy.\n>>\n>> Right. It's meant to take the \"localhost/wraparound connection\" out of a\n>> class of special things we have to worry about, and make it completely\n>> boring.\n> \n> Again, trying to get at a more concrete example- the concern here is a\n> user with CREATE SERVER ability could leverage that access to become a\n> superuser if the system is configured with 'peer' access, right?\n\nOr 'trust localhost', or 'ident [postgres user]', yes.\n\n> A\n> non-superuser is already prevented from being able to set\n> \"password_required=false\", perhaps we shouldn't allow them to set\n> \"require_auth=none\" (or have that effect) either?\n\nI think that sounds reasonable.\n\n> Perhaps the system\n> should simply forcibly set require_auth based on the credentials\n> provided in the USER MAPPING or on the connection and have require_auth\n> otherwise restricted to superuser (who could override it if they'd\n> really like to)? Perhaps if password_required=false we implicitly\n> un-set require_auth, to avoid having to make superusers change their\n> existing configurations where they've clearly already accepted that\n> credential-less connections are allowed.\n\nMm, I think I like the first idea better. If you've set a password,\nwouldn't you like to know if the server ignored it? If password_required\nis false, *and* you don't have a password, then we can drop require_auth\nwithout issue.\n\n> Automatically setting require_auth and restricting the ability of it to\n> be set on user mappings to superusers doesn't strike me as terribly\n> difficult to do and seems like it'd prevent this concern.\n> \n> Just to make sure I'm following- Robert's up-thread suggestion of an\n> 'outbound pg_hba' would be an additional restriction when it comes to\n> what a user who can use CREATE SERVER is allowed to do?\n\nYes. That can provide additional safety in the case where you really\nneed to take the require_auth checks away for whatever reason. I think\nit's just a good in-depth measure, and if we don't extend the protocol\nin some way to do a pre-auth check, it's also the way for the DBA to\nbless known-good connection paths.\n\nThanks,\n--Jacob\n\n\n","msg_date":"Wed, 12 Apr 2023 11:24:33 -0700","msg_from":"Jacob Champion <jchampion@timescale.com>","msg_from_op":false,"msg_subject":"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security"},{"msg_contents":"On Wed, Apr 12, 2023 at 5:50 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > Anyway, I don't think as such there is any problem\n> > with restarting the worker even when the subscription owner is a\n> > superuser, so adjusted the check accordingly.\n>\n> LGTM.\n>\n\nThanks. I am away for a few days so can push it only next week.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 13 Apr 2023 08:02:07 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Apr 13, 2023 at 8:02 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n>\n> On Wed, Apr 12, 2023 at 5:50 PM Robert Haas <robertmhaas@gmail.com> wrote:\n> >\n> > On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > > Anyway, I don't think as such there is any problem\n> > > with restarting the worker even when the subscription owner is a\n> > > superuser, so adjusted the check accordingly.\n> >\n> > LGTM.\n> >\n>\n> Thanks. I am away for a few days so can push it only next week.\n>\n\nPushed. I noticed that we didn't display this new subscription option\n'password_required' in \\dRs+:\n\npostgres=# \\dRs+\n\n List of subscriptions\n Name | Owner | Enabled | Publication | Binary | Streaming |\nTwo-phase commit | Disable on error | Origin | Run as Owner? |\nSynchronous commit | Conninfo | Skip LSN\n\nIs that intentional? Sorry, if it was discussed previously because I\nhaven't followed this discussion in detail.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 20 Apr 2023 10:38:02 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> Pushed. I noticed that we didn't display this new subscription option\n> 'password_required' in \\dRs+:\n>\n> postgres=# \\dRs+\n>\n> List of subscriptions\n> Name | Owner | Enabled | Publication | Binary | Streaming |\n> Two-phase commit | Disable on error | Origin | Run as Owner? |\n> Synchronous commit | Conninfo | Skip LSN\n>\n> Is that intentional? Sorry, if it was discussed previously because I\n> haven't followed this discussion in detail.\n\nNo, I don't think that's intentional. I just didn't think about it.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 20 Apr 2023 16:18:58 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, 21 Apr 2023 at 01:49, Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > Pushed. I noticed that we didn't display this new subscription option\n> > 'password_required' in \\dRs+:\n> >\n> > postgres=# \\dRs+\n> >\n> > List of subscriptions\n> > Name | Owner | Enabled | Publication | Binary | Streaming |\n> > Two-phase commit | Disable on error | Origin | Run as Owner? |\n> > Synchronous commit | Conninfo | Skip LSN\n> >\n> > Is that intentional? Sorry, if it was discussed previously because I\n> > haven't followed this discussion in detail.\n>\n> No, I don't think that's intentional. I just didn't think about it.\n\nHere is a patch to display Password required with \\dRs+ command. Also\nadded one test to describe subscription when password_required is\nfalse, as all the existing tests were there only for password_required\nas true.\n\nRegards,\nVignesh","msg_date":"Fri, 21 Apr 2023 12:29:50 +0530","msg_from":"vignesh C <vignesh21@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Apr 21, 2023 at 12:30 PM vignesh C <vignesh21@gmail.com> wrote:\n>\n> On Fri, 21 Apr 2023 at 01:49, Robert Haas <robertmhaas@gmail.com> wrote:\n> >\n> > On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > > Pushed. I noticed that we didn't display this new subscription option\n> > > 'password_required' in \\dRs+:\n> > >\n> > > postgres=# \\dRs+\n> > >\n> > > List of subscriptions\n> > > Name | Owner | Enabled | Publication | Binary | Streaming |\n> > > Two-phase commit | Disable on error | Origin | Run as Owner? |\n> > > Synchronous commit | Conninfo | Skip LSN\n> > >\n> > > Is that intentional? Sorry, if it was discussed previously because I\n> > > haven't followed this discussion in detail.\n> >\n> > No, I don't think that's intentional. I just didn't think about it.\n>\n> Here is a patch to display Password required with \\dRs+ command. Also\n> added one test to describe subscription when password_required is\n> false, as all the existing tests were there only for password_required\n> as true.\n>\n\nLGTM. Let's see if Robert or others have any comments, otherwise, I'll\npush this early next week.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 21 Apr 2023 17:48:51 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Apr 21, 2023 at 8:19 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> LGTM. Let's see if Robert or others have any comments, otherwise, I'll\n> push this early next week.\n\nLGTM too.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 21 Apr 2023 08:51:08 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Fri, Apr 21, 2023 at 6:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Fri, Apr 21, 2023 at 8:19 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > LGTM. Let's see if Robert or others have any comments, otherwise, I'll\n> > push this early next week.\n>\n> LGTM too.\n>\n\nPushed.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Mon, 24 Apr 2023 11:28:48 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tuesday, April 4, 2023 1:57 AM Robert Haas <robertmhaas@gmail.com> wrote:\r\n> \r\n> On Sat, Apr 1, 2023 at 12:00 PM Alexander Lakhin <exclusion@gmail.com>\r\n> wrote:\r\n> > I've managed to reproduce it using the following script:\r\n> > for ((i=1;i<=10;i++)); do\r\n> > echo \"iteration $i\"\r\n> > echo \"\r\n> > CREATE ROLE sub_user;\r\n> > CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\r\n> > PUBLICATION testpub WITH (connect = false); ALTER SUBSCRIPTION\r\n> > testsub ENABLE; DROP SUBSCRIPTION testsub; SELECT pg_sleep(0.001);\r\n> > DROP ROLE sub_user; \" | psql psql -c \"ALTER SUBSCRIPTION testsub\r\n> > DISABLE;\"\r\n> > psql -c \"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\"\r\n> > psql -c \"DROP SUBSCRIPTION testsub;\"\r\n> > grep 'TRAP' server.log && break\r\n> > done\r\n> \r\n> After a bit of experimentation this repro worked for me -- I needed\r\n> -DRELCACHE_FORCE_RELEASE as well, and a bigger iteration count. I verified\r\n> that the patch fixed it, and committed the patch with the addition of a\r\n> comment.\r\n\r\nThanks for pushing!\r\n\r\nWhile testing this, I found a similar problem in table sync worker,\r\nas we also invoke superuser_arg() in table sync worker which is not in a\r\ntransaction.\r\n\r\nLogicalRepSyncTableStart\r\n...\r\n\t/* Is the use of a password mandatory? */\r\n\tmust_use_password = MySubscription->passwordrequired &&\r\n\t\t!superuser_arg(MySubscription->owner);\r\n\r\n#0 0x00007f18bb55aaff in raise () from /lib64/libc.so.6\r\n#1 0x00007f18bb52dea5 in abort () from /lib64/libc.so.6\r\n#2 0x0000000000b69a22 in ExceptionalCondition (conditionName=0xda4338 \"IsTransactionState()\", fileName=0xda403e \"catcache.c\", lineNumber=1208) at assert.c:66\r\n#3 0x0000000000b4842a in SearchCatCacheInternal (cache=0x27cab80, nkeys=1, v1=10, v2=0, v3=0, v4=0) at catcache.c:1208\r\n#4 0x0000000000b48329 in SearchCatCache1 (cache=0x27cab80, v1=10) at catcache.c:1162\r\n#5 0x0000000000b630c7 in SearchSysCache1 (cacheId=11, key1=10) at syscache.c:825\r\n#6 0x0000000000b982e3 in superuser_arg (roleid=10) at superuser.c:70\r\n\r\nI can reproduce this via gdb following similar steps in [1].\r\n\r\nI think we need to move this call into a transaction as well and here is an attempt\r\nto do that.\r\n\r\n[1] https://www.postgresql.org/message-id/OS0PR01MB5716E596E4FB83DE46F592FE948C9%40OS0PR01MB5716.jpnprd01.prod.outlook.com\r\n\r\nBest Regards,\r\nHou zj","msg_date":"Fri, 12 May 2023 09:58:31 +0000","msg_from":"\"Zhijie Hou (Fujitsu)\" <houzj.fnst@fujitsu.com>","msg_from_op":false,"msg_subject":"RE: Non-superuser subscription owners"},{"msg_contents":"On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\n<houzj.fnst@fujitsu.com> wrote:\n>\n>\n> I can reproduce this via gdb following similar steps in [1].\n>\n> I think we need to move this call into a transaction as well and here is an attempt\n> to do that.\n>\n\nI am able to reproduce this issue following the steps mentioned by you\nand the proposed patch to fix the issue looks good to me.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 13 Jun 2023 14:25:50 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n>\n> On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\n> <houzj.fnst@fujitsu.com> wrote:\n> >\n> >\n> > I can reproduce this via gdb following similar steps in [1].\n> >\n> > I think we need to move this call into a transaction as well and here is an attempt\n> > to do that.\n> >\n>\n> I am able to reproduce this issue following the steps mentioned by you\n> and the proposed patch to fix the issue looks good to me.\n>\n\nI'll push this tomorrow unless there are any suggestions or comments.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 13 Jun 2023 14:29:05 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\n>\n> On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\n> <houzj.fnst@fujitsu.com> wrote:\n> >\n> >\n> > I can reproduce this via gdb following similar steps in [1].\n> >\n> > I think we need to move this call into a transaction as well and here is an attempt\n> > to do that.\n> >\n>\n> I am able to reproduce this issue following the steps mentioned by you\n> and the proposed patch to fix the issue looks good to me.\n>\n\nToday, again looking at the patch, it seems to me that it would be\nbetter if we can fix this without starting a new transaction. Won't it\nbe better if we move this syscall to a place where we are fetching\nrelstate (GetSubscriptionRelState()) a few lines above? I understand\nby doing that in some cases like when copy_data = false, we may do\nthis syscall unnecessarily but OTOH, starting a new transaction just\nfor a syscall (superuser_arg()) also doesn't seem like a good idea to\nme.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Wed, 14 Jun 2023 07:41:01 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Wednesday, June 14, 2023 10:11 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\r\n> \r\n> On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\r\n> >\r\n> > On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\r\n> > <houzj.fnst@fujitsu.com> wrote:\r\n> > >\r\n> > >\r\n> > > I can reproduce this via gdb following similar steps in [1].\r\n> > >\r\n> > > I think we need to move this call into a transaction as well and\r\n> > > here is an attempt to do that.\r\n> > >\r\n> >\r\n> > I am able to reproduce this issue following the steps mentioned by you\r\n> > and the proposed patch to fix the issue looks good to me.\r\n> >\r\n> \r\n> Today, again looking at the patch, it seems to me that it would be better if we\r\n> can fix this without starting a new transaction. Won't it be better if we move this\r\n> syscall to a place where we are fetching relstate (GetSubscriptionRelState()) a\r\n> few lines above? I understand by doing that in some cases like when copy_data\r\n> = false, we may do this syscall unnecessarily but OTOH, starting a new\r\n> transaction just for a syscall (superuser_arg()) also doesn't seem like a good\r\n> idea to me.\r\n\r\nMakes sense to me, here is the updated patch which does the same.\r\n\r\nBest Regards,\r\nHou zj","msg_date":"Wed, 14 Jun 2023 03:53:54 +0000","msg_from":"\"Zhijie Hou (Fujitsu)\" <houzj.fnst@fujitsu.com>","msg_from_op":false,"msg_subject":"RE: Non-superuser subscription owners"},{"msg_contents":"On 2023-Jun-13, Amit Kapila wrote:\n\n> I'll push this tomorrow unless there are any suggestions or comments.\n\nNote the proposed commit message is wrong about which commit is to blame\nfor the original problem -- it mentions e7e7da2f8d57 twice, but one of\nthem is actually c3afe8cf5a1e.\n\n-- \nÁlvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/\n\n\n","msg_date":"Thu, 15 Jun 2023 19:48:44 +0200","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Thu, Jun 15, 2023 at 11:18 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\n>\n> On 2023-Jun-13, Amit Kapila wrote:\n>\n> > I'll push this tomorrow unless there are any suggestions or comments.\n>\n> Note the proposed commit message is wrong about which commit is to blame\n> for the original problem -- it mentions e7e7da2f8d57 twice, but one of\n> them is actually c3afe8cf5a1e.\n>\n\nRight, I also noticed this and changed it before pushing, See\nhttps://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=b5c517379a40fa1af84c0852aa3730a5875a6482\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Fri, 16 Jun 2023 07:37:42 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Non-superuser subscription owners"},{"msg_contents":"On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Mon, 2023-02-27 at 16:13 -0500, Robert Haas wrote:\n> > On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > > I think you are saying that we should still run Alice's code with\n> > > the\n> > > privileges of Bob, but somehow make that safe(r) for Bob. Is that\n> > > right?\n> >\n> > Yeah. That's the idea I was floating, at least.\n>\n> Isn't that a hard problem; maybe impossible?\n\nI want to flesh out the ideas I previously articulated in this area a bit more.\n\nAs a refresher, the scenario I'm talking about is any one in which one\nuser, who I'll call Bob, does something that results in executing code\nprovided by another user, who I'll call Alice. The most obvious way\nthat this can happen is if Bob performs some operation that targets a\ntable owned by Alice. That operation might be DML, like an INSERT or\nUPDATE; or it might be some other kind of maintenance command that can\ncause code execution, like REINDEX, which can evaluate index\nexpressions. The code being executed might be run either as Alice or\nas Bob, depending on how it's been attached to the table and what\noperation is being performed and maybe whether some function or\nprocedure that might contain it is SECURITY INVOKER or SECURITY\nDEFINER. Regardless of the details, our concern is that Alice's code\nmight do something that Bob does not like. This is a particularly\nlively concern if the code happens to be running with the privileges\nof Bob, because then Alice might try to do something like access\nobjects for which Bob has permissions and Alice does not. But the\nproblems don't completely go away if the code is being run as Alice,\nbecause even then, Alice could try to manipulate the session state in\nsome way that will cause Bob to hose himself later on. The existing\nSECURITY_RESTRICTED_OPERATION flag defends against some scenarios of\nthis type, but at present we also rely heavily on Bob being *very*\ncareful, as Jeff has highlighted rather compellingly.\n\nI think we can do better, both in the case where Bob is running code\nprovided by Alice using his own permissions, and also in the case\nwhere Bob is running code provided by Alice using Alice's permissions.\nTo that end, I'd like to define a few terms. First, let's define the\nprovider of a piece of code as either (a) the owner of the function or\nprocedure that contains it or (b) the owner of the object to which\nit's directly attached or (c) the session user, for code directly\nentered at top level. For example, if Alice owns a table T1 and\napplies a default expression which uses a function provided by\nCharlie, and Bob then inserts into T1, then Bob provides the insert\nstatement, Alice provides the default expression, and Charlie provides\nthe code inside the function. I assert that in every context where\nPostgreSQL evaluates expressions or runs SQL statements, there's a\nwell-defined provider for the expression or statement, and we can make\nthe system track it if we want to. Second, I'd like to define trust.\nUsers trust themselves, and they also trust users who have a superset\nof their permissions, a category that most typically just includes\nsuperusers but could include others if role grants are in use. A user\ncan also declare through some mechanism or other that they trust\nanother user even if that other user does not have a superset of their\npermissions. Such a declaration carries the risk that the trusted user\ncould hijack the trusting user's permissions; we would document and\ndisclaim this risk.\n\nFinally, let's define sandboxing. When code is sandboxed, the set of\noperations that it is allowed to perform is restricted. Sandboxing\nisn't necessarily all or nothing; there can be different categories of\noperations and we can allow some and deny others, if we wish.\nObviously this is quite a bit of work to implement, but I don't think\nit's unmanageable. YMMV. To keep things simple for purposes of\ndiscussion, I'm going to just define two levels of sandboxing for the\nmoment; I think we might want more. If code is fully sandboxed, it can\nonly do the following things:\n\n1. Compute stuff. There's no restriction on the permissible amount of\ncompute; if you call untrusted code, nothing prevents it from running\nforever.\n2. Call other code. This may be done by a function call or a command\nsuch as CALL or DO, all subject to the usual permissions checks but no\nfurther restrictions.\n3. Access the current session state, without modifying it. For\nexample, executing SHOW or current_setting() is fine.\n4. Transiently modify the current session state in ways that are\nnecessarily reversed before returning to the caller. For example, an\nEXCEPTION block or a configuration change driven by proconfig is fine.\n5. Produce messages at any log level. This includes any kind of ERROR.\n\nFully sandboxed code can't access or modify data beyond what gets\npassed to it, with the exception of the session state mentioned above.\nThis includes data inside of PostgreSQL, like tables or statistics, as\nwell as data outside of PostgreSQL, like files that it might try to\nread by calling pg_read_file(). If it tries, an ERROR occurs.\n\nPartially sandboxed code is much less restricted. Partially sandboxed\ncode can do almost anything that unsandboxed code can do, but with one\nimportant exception: it can't modify the session state. This means it\ncan't run commands like CLOSE, DEALLOCATE, DECLARE, DISCARD, EXECUTE,\nFETCH, LISTEN, MOVE, PREPARE, or UNLISTEN. Nor can it try to COMMIT or\nROLLBACK the current transaction or set up a SAVEPOINT or ROLLBACK TO\nSAVEPOINT. Nor can it use SET or set_config() to change a parameter\nvalue.\n\nWith those definitions in hand, I think it's possible to propose a\nmeaningful security model:\n\nRule #1: If the current user does not trust the provider, the code is\nfully sandboxed.\nRule #2: If the session user does not trust the provider either of the\ncurrently-running code or of any other code that's still on the call\nstack, the code is partially sandboxed.\n\nLet's take a few examples. First, suppose Alice has a table and it has\nsome associated code for which the provider is always Alice. That is,\nshe may have default expressions or index expressions for which she is\nnecessarily the provider, and she may have triggers, but in this\nexample she owns the functions or procedures called by those triggers\nand is thus the provider for those as well. Now, Bob, who does not\ntrust Alice, does something to Alice's table. The code might run as\nBob (by default) and then it will be fully sandboxed because of rule\n#1. Or there might be a SECURITY DEFINER function or procedure\ninvolved causing the code to run as Alice, in which case the code will\nbe partially sandboxed because of rule #2. I argue that Bob is pretty\nsafe here. Alice can't make any durable changes to Bob's session state\nno matter what she does, and if she provides code that runs as Bob it\ncan only do innocuous things like calculating x+y or x || y or running\ngenerate_series() or examining current_role. Yes, it could go into a\nloop, but that doesn't compromise Bob's account: he can hit ^C or set\nstatement_timeout. If she provides code that runs as herself it can\nmake use of her privileges (but not Bob's) as long as it doesn't try\nto touch the session state. So Bob is pretty safe.\n\nNow, suppose instead that Bob has a table but some code that is\nattached to it can call a function that is owned by Alice. In this\ncase, as long as everything on the call stack is provided by Bob,\nthere are no restrictions. But as soon as we enter Alice's function,\nthe code is fully sandboxed unless it arranges to switch to Alice's\npermissions using SECURITY DEFINER, in which case it's still partially\nsandboxed. Again, it's hard to see how Alice can get any leverage\nhere.\n\nFinally, suppose Alice has a table and attaches a trigger to it that\ncalls a function provided by Charlie. Bob now does something to this\ntable that results in the execution of this trigger. If the current\nuser -- which will be either Alice or Bob depending on whether the\nfunction is SECURITY DEFINER -- does not trust Charlie, the code\ninside the trigger is going to run fully sandboxed because of rule #1.\nBut even if the current user does trust Charlie, the code inside the\ntrigger is still going to be partially sandboxed unless Bob trusts\nBOTH Alice AND Charlie because of rule #2. This seems appropriate,\nbecause in this situation, either Alice or Charlie could be trying to\nfool Bob into taking some action he doesn't intend to take by\ntinkering with his session.\n\nIn general if we have a great big call stack that involves calling a\nwhole bunch of functions either as SECURITY INVOKER or as SECURITY\nDEFINER, changing the session state is blocked unless the session user\ntrusts the owners of all of those functions. And if we got to any of\nthose functions by means of code attached directly to tables, like an\nindex expression or default expression, changing the session state is\nblocked unless the session user also trusts the owners of those\ntables.\n\nI see a few obvious objections to this line of attack that someone\nmight raise, and I'd like to address them now. First, somebody might\nargue that this is too hard to implement. I don't think so, because a\nlot of things can be blocked from common locations. However, it will\nbe necessary to go through all the functions we ship and add checks in\na bunch of places to individual functions. That's a pain, but it's not\nthat different from what we've already done with PARALLEL { SAFE |\nRESTRICTED | UNSAFE } or LEAKPROOF. Those weren't terribly enjoyable\nexercises for me and I made some mistakes categorizing some things,\nbut the job got done and those mechanisms are accepted infrastructure\nnow. Second, somebody might argue that full sandboxing is such a\ndraconian set of restrictions that it will inconvenience users greatly\nor that it's pointless to even allow anything to be executed or\nsomething along those lines. I think that argument has some merit, but\nI think the restrictions sound worse than they actually are in\ncontext. For instance, have you ever written a default expression for\na column that would fail under full sandboxing? I wouldn't be\nsurprised if you have, but I also bet it's a fairly small percentage\nof cases. I think a lot of things that people want to do as a\npractical matter will be totally fine. I can think of exceptions, most\nobviously reading from a random-number generator that has a\nuser-controllable seed, which technically qualifies as tinkering with\nthe session state. But a lot of things are going to work fine, and the\nthings that do fall afoul of a mechanism like this probably deserve\nsome study and examination. If you're writing index expressions that\ndo anything more than simple calculation, it's probably fine for the\nsystem to raise an eyebrow about that. Even if they do something as\nsimple as reading from another table, that's not necessarily going to\ndump and restore properly, even if it's secure, because the table\nordering dependencies won't be clear to pg_dump.\n\nAnd that brings me to another point, which is that we might think of\nsandboxing some operations, either by default or unconditionally, for\nreasons other than trust or the lack of it. There's a lot of things\nthat you COULD do in an index expression that you really SHOULD NOT\ndo. As mentioned, even reading a table is pretty sketchy, but should a\nfunction called from an index expression ever be allowed to execute\nDDL? Is it reasonable if such a function wants to execute CREATE\nTABLE? Even a temporary table is dubious, and a non-temporary table is\nreally dubious. What if such a function wants to ALTER ROLE ...\nSUPERUSER? I think that's bonkers and should almost certainly be\ncategorically denied. Probably someone is trying to hack something,\nand even if they aren't, it's still nuts. So I would argue that in a\ncontext like an index expression, some amount of sandboxing -- not\nnecessarily corresponding to either of the levels described above --\nis probably a good idea, not based on the relationship between\nwhatever users are involved, but based rather on the context. There's\nroom for a lot of bikeshedding here and I don't think this kind of\nthing is necessarily the top priority, but I think it's worth thinking\nabout.\n\nFinally, I'd like to note that partial sandboxing can be viewed as a\nstrengthening of restrictions that we already have in the form of\nSECURITY_RESTRICTED_OPERATION. I can't claim to be an authority on the\nevolution of that flag, but I think that up to this point the general\nphilosophy has been to insert the smallest possible plug in the dike.\nWhen a definite security problem is discovered, somebody tries to\nblock just enough stuff to make it not demonstrably insecure. However,\nI feel that the surface area for things to go wrong is rather large,\nand we'd be better off with a more comprehensive series of\nrestrictions. We likely have some security issues that haven't been\nfound yet, and even something we wouldn't classify as a security\nvulnerability can still be a pitfall for the unwary. I imagine that\nSECURITY_RESTRICTED_OPERATION might end up getting subsumed into what\nI'm here calling partial sandboxing, but I'm not quite sure about that\nbecause right now this is just a theoretical description of a system,\nnot something for which I've written any code.\n\nThanks,\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 31 Aug 2023 11:25:33 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"sandboxing untrusted code"},{"msg_contents":"On Thu, 2023-08-31 at 11:25 -0400, Robert Haas wrote:\n> As a refresher, the scenario I'm talking about is any one in which\n> one\n> user, who I'll call Bob, does something that results in executing\n> code\n> provided by another user, who I'll call Alice. The most obvious way\n> that this can happen is if Bob performs some operation that targets a\n> table owned by Alice. That operation might be DML, like an INSERT or\n> UPDATE; or it might be some other kind of maintenance command that\n> can\n> cause code execution, like REINDEX, which can evaluate index\n> expressions.\n\nREINDEX executes index expressions as the table owner. (You are correct\nthat INSERT executes index expressions as the inserting user.)\n\n> The code being executed might be run either as Alice or\n> as Bob, depending on how it's been attached to the table and what\n> operation is being performed and maybe whether some function or\n> procedure that might contain it is SECURITY INVOKER or SECURITY\n> DEFINER. Regardless of the details, our concern is that Alice's code\n> might do something that Bob does not like. This is a particularly\n> lively concern if the code happens to be running with the privileges\n> of Bob, because then Alice might try to do something like access\n> objects for which Bob has permissions and Alice does not.\n\nAgreed.\n\n\n> 1. Compute stuff. There's no restriction on the permissible amount of\n> compute; if you call untrusted code, nothing prevents it from running\n> forever.\n> 2. Call other code. This may be done by a function call or a command\n> such as CALL or DO, all subject to the usual permissions checks but\n> no\n> further restrictions.\n> 3. Access the current session state, without modifying it. For\n> example, executing SHOW or current_setting() is fine.\n> 4. Transiently modify the current session state in ways that are\n> necessarily reversed before returning to the caller. For example, an\n> EXCEPTION block or a configuration change driven by proconfig is\n> fine.\n> 5. Produce messages at any log level. This includes any kind of\n> ERROR.\n\nNothing in that list really exercises privileges (except #2?). If those\nare the allowed set of things a sandboxed function can do, is a\nsandboxed function equivalent to a function running with no privileges\nat all?\n\nPlease explain #2 in a bit more detail. Whose EXECUTE privileges would\nbe used (I assume it depende on SECURITY DEFINER/INVOKER)? Would the\ncalled code also be sandboxed?\n\n> In general if we have a great big call stack that involves calling a\n> whole bunch of functions either as SECURITY INVOKER or as SECURITY\n> DEFINER, changing the session state is blocked unless the session\n> user\n> trusts the owners of all of those functions.\n\nThat clarifies the earlier mechanics you described, thank you.\n\n> And if we got to any of\n> those functions by means of code attached directly to tables, like an\n> index expression or default expression, changing the session state is\n> blocked unless the session user also trusts the owners of those\n> tables.\n> \n> I see a few obvious objections to this line of attack that someone\n> might raise, and I'd like to address them now. First, somebody might\n> argue that this is too hard to implement.\n\nThat seems to be a response to my question above: \"Isn't that a hard\nproblem; maybe impossible?\".\n\nLet me qualify that: if the function is written by Alice, and the code\nis able to really exercise the privileges of the caller (Bob), then it\nseems really hard to make it safe for the caller.\n\nIf the function is sandboxed such that it's not really using Bob's\nprivileges (it's just nominally running as Bob) that's a much more\ntractable problem.\n\nI believe there's some nuance to your proposal where some of Bob's\nprivileges could be used safely, but I'm not clear on exactly which\nones. The difficulty of the implementation would depend on these\ndetails.\n\n> Second, somebody might argue that full sandboxing is such a\n> draconian set of restrictions that it will inconvenience users\n> greatly\n> or that it's pointless to even allow anything to be executed or\n> something along those lines. I think that argument has some merit,\n> but\n> I think the restrictions sound worse than they actually are in\n> context.\n\n+100. We should make typical cases easy to secure.\n\n> Even if they do something as\n> simple as reading from another table, that's not necessarily going to\n> dump and restore properly, even if it's secure, because the table\n> ordering dependencies won't be clear to pg_dump.\n\nA good point. A lot of these extraordinary cases are either incredibly\nfragile or already broken.\n\n> What if such a function wants to ALTER ROLE ...\n> SUPERUSER? I think that's bonkers and should almost certainly be\n> categorically denied.\n\n...also agreed, a lot of these extraordinary cases are really just\nsurface area for attack with no legitimate use case.\n\n\n\n\nOne complaint (not an objection, because I don't think we have\nthe luxury of objecting to viable proposals when it comes to improving\nour security model):\n\nAlthough your proposal sounds like a good security backstop, it feels\nlike it's missing the point that there are different _kinds_ of\nfunctions. We already have the IMMUTABLE marker and we already have\nruntime checks to make sure that immutable functions can't CREATE\nTABLE; why not build on that mechanism or create new markers?\n\nDeclarative markers are nice because they are easier to test: if Alice\nwrites a function and declares it as IMMUTABLE, she can test it before\neven using it in an index expression and it will fail whatever runtime\nprotections IMMUTABLE offers. If we instead base it on the session user\nand call stack, Alice wouldn't be able to test it effectively, only Bob\ncan test it.\n\nIn other words, there are some consistency aspects to how we run code\nthat go beyond pure security. A function author typically has\nassumptions about the execution context of a function (the user, the\nsandbox restrictions, the search_path, etc.) and guiding users towards\na consistent execution context in typical cases is a good thing.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Thu, 31 Aug 2023 17:57:25 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: sandboxing untrusted code"},{"msg_contents":"On Thu, Aug 31, 2023 at 8:57 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > As a refresher, the scenario I'm talking about is any one in which\n> > one\n> > user, who I'll call Bob, does something that results in executing\n> > code\n> > provided by another user, who I'll call Alice. The most obvious way\n> > that this can happen is if Bob performs some operation that targets a\n> > table owned by Alice. That operation might be DML, like an INSERT or\n> > UPDATE; or it might be some other kind of maintenance command that\n> > can\n> > cause code execution, like REINDEX, which can evaluate index\n> > expressions.\n>\n> REINDEX executes index expressions as the table owner. (You are correct\n> that INSERT executes index expressions as the inserting user.)\n\nI was speaking here of who provided the code, rather than whose\ncredentials were used to execute it. The index expressions are\nprovided by the table owner no matter who evaluates them in a\nparticular case.\n\n> > 1. Compute stuff. There's no restriction on the permissible amount of\n> > compute; if you call untrusted code, nothing prevents it from running\n> > forever.\n> > 2. Call other code. This may be done by a function call or a command\n> > such as CALL or DO, all subject to the usual permissions checks but\n> > no\n> > further restrictions.\n> > 3. Access the current session state, without modifying it. For\n> > example, executing SHOW or current_setting() is fine.\n> > 4. Transiently modify the current session state in ways that are\n> > necessarily reversed before returning to the caller. For example, an\n> > EXCEPTION block or a configuration change driven by proconfig is\n> > fine.\n> > 5. Produce messages at any log level. This includes any kind of\n> > ERROR.\n>\n> Nothing in that list really exercises privileges (except #2?). If those\n> are the allowed set of things a sandboxed function can do, is a\n> sandboxed function equivalent to a function running with no privileges\n> at all?\n\nClose but not quite. As you say, #2 does exercise privileges. Also,\neven if no privileges are exercised, you could still refer to\nCURRENT_ROLE, and I think you could also call a function like\nhas_table_privilege. Your identity hasn't changed, but you're\nrestricted from exercising some of your privileges. Really, you still\nhave them, but they're just not available to you in that situation.\n\n> Please explain #2 in a bit more detail. Whose EXECUTE privileges would\n> be used (I assume it depende on SECURITY DEFINER/INVOKER)? Would the\n> called code also be sandboxed?\n\nNothing in this proposed system has any impact on whose privileges are\nused in any particular context, so any privilege checks conducted\npursuant to #2 are performed as the same user who would perform them\ntoday. Whether the called code would be sandboxed depends on how the\nrules I articulated in the previous email would apply to it. Since\nthose rules depend on the user IDs, if the called code is owned by the\nsame user as the calling code and is SECURITY INVOKER, then those\nrules apply in the same way and the same level of sandboxing will\napply. But if the called function is owned by a different user or is\nSECURITY DEFINER, then the rules might apply differently to the called\ncode than the calling code. It's possible this isn't quite good enough\nand that some adjustments to the rules are necessary; I'm not sure.\n\n> Let me qualify that: if the function is written by Alice, and the code\n> is able to really exercise the privileges of the caller (Bob), then it\n> seems really hard to make it safe for the caller.\n>\n> If the function is sandboxed such that it's not really using Bob's\n> privileges (it's just nominally running as Bob) that's a much more\n> tractable problem.\n\nAgreed.\n\n> One complaint (not an objection, because I don't think we have\n> the luxury of objecting to viable proposals when it comes to improving\n> our security model):\n>\n> Although your proposal sounds like a good security backstop, it feels\n> like it's missing the point that there are different _kinds_ of\n> functions. We already have the IMMUTABLE marker and we already have\n> runtime checks to make sure that immutable functions can't CREATE\n> TABLE; why not build on that mechanism or create new markers?\n\nI haven't ruled that out completely, but there's some subtlety here\nthat doesn't exist in those other cases. If the owner of a function\nmarks it wrongly in terms of volatility or parallel safety, then they\nmight make queries run more slowly than they should, or they might\nmake queries return wrong answers, or error out, or even end up with\nmessed-up indexes. But none of that threatens the stability of the\nsystem in any very deep way, or the security of the system. It's no\ndifferent than putting a CHECK (false) constraint on a table, or\nsomething like that: it might make the system not work, and if that\nhappens, then you can fix it. Here, however, we can't trust the owners\nof functions to label those functions accurately. It won't do for\nAlice to create a function and then apply the NICE_AND_SAFE marker to\nit. That defeats the whole point. We need to know the real behavior of\nAlice's function, not the behavior that Alice says it has.\n\nNow, in the case of a C function, things are a bit different. We can't\ninspect the generated machine code and know what the function does,\nbecause of that pesky halting problem. We could handle that either\nthrough function labeling, since only superusers can create C\nfunctions, or by putting checks directly in the C code. I was somewhat\ninclined toward the latter approach, but I'm not completely sure yet\nwhat makes sense. Thinking about your comments here made me realize\nthat there are other procedural languages to worry about, too, like\nPL/python or PL/perl or PL/sh. Whatever we do for the C functions will\nhave to be extended to those cases somehow as well. If we label\nfunctions, then we'll have to allow superusers only to label functions\nin these languages as well and make the default label \"this is\nunsafe.\" If we put checks in the C code then I guess any given PL\nneeds to certify that it knows about sandboxing or have all of its\nfunctions treated as unsafe. I think doing this at the C level would\nbe better, strictly speaking, because it's more granular. Imagine a\nfunction that only conditionally does some prohibited action - it can\nbe allowed to work in the cases where it does not attempt the\nprohibited operation, and blocked when it does. Labeling is\nall-or-nothing.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 1 Sep 2023 09:12:22 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: sandboxing untrusted code"},{"msg_contents":"On Fri, 2023-09-01 at 09:12 -0400, Robert Haas wrote:\n> Close but not quite. As you say, #2 does exercise privileges. Also,\n> even if no privileges are exercised, you could still refer to\n> CURRENT_ROLE, and I think you could also call a function like\n> has_table_privilege. Your identity hasn't changed, but you're\n> restricted from exercising some of your privileges. Really, you still\n> have them, but they're just not available to you in that situation.\n\nWhich privileges are available in a sandboxed environment, exactly? Is\nit kind of like masking away all privileges except EXECUTE, or are\nother privileges available, like SELECT?\n\nAnd the distinction that you are drawing between having the privileges\nbut them (mostly) not being available, versus not having the privileges\nat all, is fairly subtle. Some examples showing why that distinction is\nimportant would be helpful.\n\n> \n> > Although your proposal sounds like a good security backstop, it\n> > feels\n> > like it's missing the point that there are different _kinds_ of\n> > functions. We already have the IMMUTABLE marker and we already have\n> > runtime checks to make sure that immutable functions can't CREATE\n> > TABLE; why not build on that mechanism or create new markers?\n\n...\n\n> Here, however, we can't trust the owners\n> of functions to label those functions accurately.\n\nOf course, but observe:\n\n =# CREATE FUNCTION f(i INT) RETURNS INT IMMUTABLE LANGUAGE plpgsql AS\n $$\n BEGIN\n CREATE TABLE x(t TEXT);\n RETURN 42 + i;\n END;\n $$;\n\n =# SELECT f(2);\n ERROR: CREATE TABLE is not allowed in a non-volatile function\n CONTEXT: SQL statement \"CREATE TABLE x(t TEXT)\"\n PL/pgSQL function f(integer) line 3 at SQL statement\n\nThe function f() is called at the top level, not as part of any index\nexpression or other special context. But it fails to CREATE TABLE\nsimply because that's not an allowed thing for an IMMUTABLE function to\ndo. That tells me right away that my function isn't going to work, and\nI can rewrite it rather than waiting for some other user to say that it\nfailed when run in a sandbox.\n\n> It won't do for\n> Alice to create a function and then apply the NICE_AND_SAFE marker to\n> it.\n\nYou can if you always execute NICE_AND_SAFE functions in a sandbox. The\ndifference is that it's always executed in a sandbox, rather than\nsometimes, so it will fail consistently.\n\n> Now, in the case of a C function, things are a bit different. We\n> can't\n> inspect the generated machine code and know what the function does,\n> because of that pesky halting problem. We could handle that either\n> through function labeling, since only superusers can create C\n> functions, or by putting checks directly in the C code. I was\n> somewhat\n> inclined toward the latter approach, but I'm not completely sure yet\n> what makes sense. Thinking about your comments here made me realize\n> that there are other procedural languages to worry about, too, like\n> PL/python or PL/perl or PL/sh. Whatever we do for the C functions\n> will\n> have to be extended to those cases somehow as well. If we label\n> functions, then we'll have to allow superusers only to label\n> functions\n> in these languages as well and make the default label \"this is\n> unsafe.\" If we put checks in the C code then I guess any given PL\n> needs to certify that it knows about sandboxing or have all of its\n> functions treated as unsafe. I think doing this at the C level would\n> be better, strictly speaking, because it's more granular. Imagine a\n> function that only conditionally does some prohibited action - it can\n> be allowed to work in the cases where it does not attempt the\n> prohibited operation, and blocked when it does. Labeling is\n> all-or-nothing.\n\nHere I'm getting a little lost in what you mean by \"prohibited\noperation\". Most languages mostly use SPI, and whatever sandboxing\nchecks you do should work there, too. Are you talking about completely\nseparate side effects like writing files or opening sockets?\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Fri, 01 Sep 2023 14:27:07 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: sandboxing untrusted code"},{"msg_contents":"On Fri, Sep 1, 2023 at 5:27 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> Which privileges are available in a sandboxed environment, exactly? Is\n> it kind of like masking away all privileges except EXECUTE, or are\n> other privileges available, like SELECT?\n\nI think I've more or less answered this already -- fully sandboxed\ncode can't make reference to external data sources, from which it\nfollows that it can't exercise SELECT (and most other privileges).\n\n> And the distinction that you are drawing between having the privileges\n> but them (mostly) not being available, versus not having the privileges\n> at all, is fairly subtle. Some examples showing why that distinction is\n> important would be helpful.\n\nI view it like this: when Bob tries to insert or update or delete\nAlice's table, and Alice has some code attached to it, Alice is\neffectively asking Bob to execute that code with his own privileges.\nIn general, I think we can reasonably expect that Bob WILL be willing\nto do this: if he didn't want to modify into Alice's table, he\nwouldn't have executed a DML statement against it, and executing the\ncode that Alice has attached to that table is a precondition of being\nallowed to perform that modification. It's Alice's table and she gets\nto set the rules. However, Bob is also allowed to protect himself. If\nhe's running Alice's code and it wants to do something with which Bob\nisn't comfortable, he can change his mind and refuse to execute it\nafter all.\n\nI always find it helpful to consider real world examples with similar\ncharacteristics. Let's say that Bob is renting a VRBO from Alice.\nAlice leaves behind, in the VRBO, a set of rules which Bob must follow\nas a condition of being allowed to rent the VRBO. Those rules include\nthings that Bob but must do at checkout time, like washing all of his\ndishes. As a matter of routine, Bob will follow Alice's checkout\ninstructions. But if Alice includes in the checkout instructions\n\"Leave your driver's license and social security card on the dining\nroom table after checkout, plus a record of all of your bank account\nnumbers,\" the security systems in Bob's brain should activate and\nprevent those instructions from getting followed.\n\nA major difference between that situation (a short term rental of\nsomeone else's house) and the in-database case (a DML statement\nagainst someone else's table) is that when Bob is following Alice's\nVRBO checkout instructions, he knows exactly what actions he is\nperforming. When he executes a DML statement against Alice's table,\nBob the human being does not actually know what Alice's triggers or\nindex expressions or whatever are causing him to do. As I see it, the\npurpose of this system is to prevent Bob from doing things that he\ndidn't intend to do. He's cool with adding 2 and 2 or concatenating\nsome strings or whatever, but probably not with reading data and\nhanding it over to Alice, and definitely not handing all of his\nprivileges over to Alice. Full sandboxing has to block that kind of\nstuff, and it needs to do so precisely because *Bob would not allow\nthose operations if he knew about them*.\n\nNow, it is not going to be possible to get that perfectly right.\nPostgreSQL can not know the state of Bob's human mind, and it cannot\nbe expected to judge with perfect accuracy what actions Bob would or\nwould not approve. However, it can make some conservative guesses. If\nBob wants to override those guesses by saying \"I trust Alice, do\nwhatever she says\" that's fine. This system attempts to prevent Bob\nfrom accidentally giving away his permissions to an adversary who has\nburied malicious code in some unexpected place. But, unlike the\nregular permissions system, it is not there to prevent Bob from doing\nthings that he isn't allowed to do. It's there to prevent Bob from\ndoing things that he didn't intend to do.\n\nAnd that's where I see the distinction between *having* permissions\nand those permissions being *available* in a particular context. Bob\nhas permission to give Alice an extra $1000 or whatever if he has the\nmoney and wishes to do so. But those permissions are probably not\n*available* in the context where Bob is following a set of\ninstructions from Alice. If Bob's brain spontaneously generated the\nidea \"let's give Alice a $1000 tip because her vacation home was\nabsolutely amazing and I am quite rich,\" he would probably go right\nahead and act on that idea and that is completely fine. But when Bob\nencounters that same idea *on a list of instructions provided by\nAlice*, the same operation is blocked *because it came from Alice*. If\nthe list of instructions from Alice said to sweep the parlor, Bob\nwould just go ahead and do it. Alice has permission to induce Bob to\nsweep the parlor, but does not have permission to induce Bob to give\nher a bunch of extra money.\n\nAnd in the database context, I think it's fine if Alice induces Bob to\ncompute some values or look at the value of work_mem, but I don't\nthink it's OK if Alice induces Bob to make her a superuser. Unless Bob\ndeclares that he trusts Alice completely, in which case it's fine if\nshe does that.\n\n> Here I'm getting a little lost in what you mean by \"prohibited\n> operation\". Most languages mostly use SPI, and whatever sandboxing\n> checks you do should work there, too. Are you talking about completely\n> separate side effects like writing files or opening sockets?\n\nYeah.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 5 Sep 2023 12:25:28 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: sandboxing untrusted code"},{"msg_contents":"On Tue, 2023-09-05 at 12:25 -0400, Robert Haas wrote:\n> I think I've more or less answered this already -- fully sandboxed\n> code can't make reference to external data sources, from which it\n> follows that it can't exercise SELECT (and most other privileges).\n\nBy what principle are we allowing EXECUTE but not SELECT? In theory, at\nleast, a function could hold secrets in the code, e.g.:\n\n CREATE FUNCTION answer_to_ultimate_question() RETURNS INT\n LANGUAGE plpgsql AS $$ BEGIN RETURN 42; END; $$;\n\nObviously that's a bad idea in plpgsql, because anyone can just read\npg_proc. And maybe C would be handled differently somehow, so maybe it\nall works.\n\nBut it feels like something is wrong there: it's fine to execute the\nanswer_to_ultimate_question() not because Bob has an EXECUTE privilege,\nbut because the sandbox renders any security concerns with *anyone*\nexecuting the function moot. So why bother checking the EXECUTE\nprivilege at all?\n\n> And that's where I see the distinction between *having* permissions\n> and those permissions being *available* in a particular context. Bob\n> has permission to give Alice an extra $1000 or whatever if he has the\n> money and wishes to do so. But those permissions are probably not\n> *available* in the context where Bob is following a set of\n> instructions from Alice. If Bob's brain spontaneously generated the\n> idea \"let's give Alice a $1000 tip because her vacation home was\n> absolutely amazing and I am quite rich,\" he would probably go right\n> ahead and act on that idea and that is completely fine. But when Bob\n> encounters that same idea *on a list of instructions provided by\n> Alice*, the same operation is blocked *because it came from Alice*.\n> If\n> the list of instructions from Alice said to sweep the parlor, Bob\n> would just go ahead and do it. Alice has permission to induce Bob to\n> sweep the parlor, but does not have permission to induce Bob to give\n> her a bunch of extra money.\n\nIn the real world example, sweeping the parlor has a (slight) cost to\nthe person doing it and it (slightly) matters who does it. In Postgres,\nwe don't do any CPU accounting per user, and it's all executed under\nthe same PID, so it really doesn't matter.\n\nSo it raises the question: why would we not simply say that this list\nof instructions should be executed by the person who wrote it, in which\ncase the existing privilege mechanism would work just fine?\n\n> And in the database context, I think it's fine if Alice induces Bob\n> to\n> compute some values or look at the value of work_mem, but I don't\n> think it's OK if Alice induces Bob to make her a superuser.\n\nIf all the code can do is compute some values or look at work_mem,\nperhaps the function needs no privileges at all (or some minimal\nprivileges)?\n\nYou explained conceptually where you're coming from, but I still don't\nsee much of a practical difference between having privileges but being\nin a context where they won't be used, and dropping the privileges\nentirely during that time. I suppose the answer is that the EXECUTE\nprivilege will still be used, but as I said above, that doesn't\nentirely make sense to me, either.\n\nRegards,\n\tJeff Davis\n\n\n\n","msg_date":"Tue, 05 Sep 2023 15:20:53 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":false,"msg_subject":"Re: sandboxing untrusted code"}],"string":"[\n {\n \"msg_contents\": \"These patches have been split off the now deprecated monolithic \\\"Delegating superuser tasks to new security roles\\\" thread at [1].\\n\\nThe purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables they lack privilege to write directly. This both allows subscriptions to be managed by non-superusers, and protects servers with subscriptions from malicious activity on the publisher side.\\n\\n\\n\\n\\n\\n\\n\\n[1] https://www.postgresql.org/message-id/flat/F9408A5A-B20B-42D2-9E7F-49CD3D1547BC%40enterprisedb.com\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Wed, 20 Oct 2021 11:40:39 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Le mercredi 20 octobre 2021, 20:40:39 CEST Mark Dilger a écrit :\\n> These patches have been split off the now deprecated monolithic \\\"Delegating\\n> superuser tasks to new security roles\\\" thread at [1].\\n> \\n> The purpose of these patches is to allow non-superuser subscription owners\\n> without risk of them overwriting tables they lack privilege to write\\n> directly. This both allows subscriptions to be managed by non-superusers,\\n> and protects servers with subscriptions from malicious activity on the\\n> publisher side.\\n\\nThank you Mark for splitting this.\\n\\nThis patch looks good to me, and provides both better security (by closing the \\n\\\"dropping superuser role\\\" loophole) and usefule features. \\n\\n\\n-- \\nRonan Dunklau\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 09:26:30 +0200\",\n \"msg_from\": \"Ronan Dunklau <ronan.dunklau@aiven.io>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 10/20/21 14:40, Mark Dilger wrote:\\n> These patches have been split off the now deprecated monolithic \\\"Delegating superuser tasks to new security roles\\\" thread at [1].\\n>\\n> The purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables they lack privilege to write directly. This both allows subscriptions to be managed by non-superusers, and protects servers with subscriptions from malicious activity on the publisher side.\\n>\\n> [1] https://www.postgresql.org/message-id/flat/F9408A5A-B20B-42D2-9E7F-49CD3D1547BC%40enterprisedb.com\\n\\n\\nThese patches look good on their face. The code changes are very\\nstraightforward.\\n\\n\\nw.r.t. this:\\n\\n+ On the subscriber, the subscription owner's privileges are\\nre-checked for\\n+ each change record when applied, but beware that a change of\\nownership for a\\n+ subscription may not be noticed immediately by the replication workers.\\n+ Changes made on the publisher may be applied on the subscriber as\\n+ the old owner. In such cases, the old owner's privileges will be\\nthe ones\\n+ that matter. Worse still, it may be hard to predict when replication\\n+ workers will notice the new ownership. Subscriptions created\\ndisabled and\\n+ only enabled after ownership has been changed will not be subject to\\nthis\\n+ race condition.\\n\\n\\nmaybe we should disable the subscription before making such a change and\\nthen re-enable it?\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 10:18:24 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"> On Nov 1, 2021, at 7:18 AM, Andrew Dunstan <andrew@dunslane.net> wrote:\\n> \\n> w.r.t. this:\\n> \\n> + On the subscriber, the subscription owner's privileges are\\n> re-checked for\\n> + each change record when applied, but beware that a change of\\n> ownership for a\\n> + subscription may not be noticed immediately by the replication workers.\\n> + Changes made on the publisher may be applied on the subscriber as\\n> + the old owner. In such cases, the old owner's privileges will be\\n> the ones\\n> + that matter. Worse still, it may be hard to predict when replication\\n> + workers will notice the new ownership. Subscriptions created\\n> disabled and\\n> + only enabled after ownership has been changed will not be subject to\\n> this\\n> + race condition.\\n> \\n> \\n> maybe we should disable the subscription before making such a change and\\n> then re-enable it?\\n\\nRight. I commented the code that way because there is a clear concern, but I was uncertain which way around the problem was best.\\n\\nALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n\\nThe attached patch demonstrates the race condition. It sets up a publisher and subscriber, and toggles the subscription on and off on the subscriber node, interleaved with inserts and deletes on the publisher node. If the ALTER SUBSCRIPTION commands were synchronous, the test results would be deterministic, with only the inserts performed while the subscription is enabled being replicated, but because the ALTER commands are asynchronous, the results are nondeterministic.\\n\\nIt is unclear that I can make ALTER SUBSCRIPTION..OWNER TO synchronous without redesigning the way workers respond to pg_subscription catalog updates generally. That may be a good project to eventually tackle, but I don't see that it is more important to close the race condition in an OWNER TO than for a DISABLE.\\n\\nThoughts?\\n\\n\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Mon, 1 Nov 2021 10:58:25 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> \\n> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n\\nHaving discussed this with Andrew off-list, we've concluded that updating the documentation for logical replication to make this point more clear is probably sufficient, but I wonder if anyone thinks otherwise?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 15:44:32 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 1, 2021 at 6:44 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> > ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n>\\n> Having discussed this with Andrew off-list, we've concluded that updating the documentation for logical replication to make this point more clear is probably sufficient, but I wonder if anyone thinks otherwise?\\n\\nThe question in my mind is whether there's some reasonable amount of\\ntime that a user should expect to have to wait for the changes to take\\neffect. If it could easily happen that the old permissions are still\\nin use a month after the change is made, I think that's probably not\\ngood. If there's reason to think that, barring unusual circumstances,\\nchanges will be noticed within a few minutes, I think that's fine.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 11:17:48 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> \\n> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n\\nI have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\\n\\nThe first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\\n\\n\\n\\n\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Wed, 3 Nov 2021 12:50:28 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-01 at 10:58 -0700, Mark Dilger wrote:\\n> It is unclear that I can make ALTER SUBSCRIPTION..OWNER TO\\n> synchronous without redesigning the way workers respond to\\n> pg_subscription catalog updates generally. That may be a good\\n> project to eventually tackle, but I don't see that it is more\\n> important to close the race condition in an OWNER TO than for a\\n> DISABLE.\\n> \\n> Thoughts?\\n\\nWhat if we just say that OWNER TO must be done by a superuser, changing\\nfrom one superuser to another, just like today? That would preserve\\nbackwards compatibility, but people with non-superuser subscriptions\\nwould need to drop/recreate them.\\n\\nWhen we eventually do tackle the problem, we can lift the restriction.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 10:08:06 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 16, 2021, at 10:08 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> On Mon, 2021-11-01 at 10:58 -0700, Mark Dilger wrote:\\n>> It is unclear .....\\n>> \\n>> Thoughts?\\n> \\n> What if we just say that OWNER TO must be done by a superuser, changing\\n> from one superuser to another, just like today? That would preserve\\n> backwards compatibility, but people with non-superuser subscriptions\\n> would need to drop/recreate them.\\n\\nThe paragraph I wrote on 11/01 and you are responding to is no longer relevant. The patch submission on 11/03 tackled the problem. Have you had a chance to take a look at the new design?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 10:12:26 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 11/3/21 15:50, Mark Dilger wrote:\\n>> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n>>\\n>> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\\n>\\n> The first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\\n\\n\\nI'm generally happier about this than the previous patch set. With the\\nexception of some slight documentation modifications I think it's\\nbasically committable. There doesn't seem to be a CF item for it but I'm\\ninclined to commit it in a couple of days time.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 15:06:23 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 16, 2021, at 12:06 PM, Andrew Dunstan <andrew@dunslane.net> wrote:\\n> \\n> There doesn't seem to be a CF item for it but I'm\\n> inclined to commit it in a couple of days time.\\n\\nhttps://commitfest.postgresql.org/36/3414/\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 12:08:04 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 11/16/21 15:08, Mark Dilger wrote:\\n>\\n>> On Nov 16, 2021, at 12:06 PM, Andrew Dunstan <andrew@dunslane.net> wrote:\\n>>\\n>> There doesn't seem to be a CF item for it but I'm\\n>> inclined to commit it in a couple of days time.\\n> https://commitfest.postgresql.org/36/3414/\\n>\\n\\nOK, got it, thanks.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 15:40:54 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-03 at 12:50 -0700, Mark Dilger wrote:\\n> The first two patches are virtually unchanged. The third updates the\\n> behavior of the apply workers, and updates the documentation to\\n> match.\\n\\nv2-0001 corrects some surprises, but may create others. Why is renaming\\nallowed, but not changing the options? What if we add new options, and\\nsome of them seem benign for a non-superuser to change?\\n\\nThe commit message part of the patch says that it's to prevent non-\\nsuperusers from being able to (effectively) create subscriptions, but\\ndon't we want privileged non-superusers to be able to create\\nsubscriptions?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 16 Nov 2021 20:11:59 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 16, 2021, at 8:11 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> On Wed, 2021-11-03 at 12:50 -0700, Mark Dilger wrote:\\n>> The first two patches are virtually unchanged. The third updates the\\n>> behavior of the apply workers, and updates the documentation to\\n>> match.\\n> \\n> v2-0001 corrects some surprises, but may create others. Why is renaming\\n> allowed, but not changing the options? What if we add new options, and\\n> some of them seem benign for a non-superuser to change?\\n\\nThe patch cannot anticipate which logical replication options may be added to the project in some later commit. We can let that commit adjust the behavior to allow the option if we agree it is sensible for non-superusers to do so.\\n\\n> The commit message part of the patch says that it's to prevent non-\\n> superusers from being able to (effectively) create subscriptions, but\\n> don't we want privileged non-superusers to be able to create\\n> subscriptions?\\n\\nPerhaps, but I don't think merely owning a subscription should entitle a role to create new subscriptions. Administrators may quite intentionally create low-power users, ones without access to anything but a single table, or a single schema, as a means of restricting the damage that a subscription might do (or more precisely, what the publisher might do via the subscription.) It would be surprising if that low-power user was then able to recreate the subscription into something different.\\n\\nWe should probably come back to this topic in a different patch, perhaps a patch that introduces a new pg_manage_subscriptions role or such.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 07:44:27 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 07:44 -0800, Mark Dilger wrote:\\n> Administrators may quite\\n> intentionally create low-power users, ones without access to anything\\n> but a single table, or a single schema, as a means of restricting the\\n> damage that a subscription might do (or more precisely, what the\\n> publisher might do via the subscription.) It would be surprising if\\n> that low-power user was then able to recreate the subscription into\\n> something different.\\n\\nI am still trying to understand this use case. It doesn't feel like\\n\\\"ownership\\\" to me, it feels more like some kind of delegation.\\n\\nIs GRANT a better fit here? That would allow more than one user to\\nREFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\\nRENAME, but I don't see why we'd separate privileges for\\nCREATE/DROP/RENAME anyway.\\n\\nThis would not address the weirdness of the existing code where a\\nsuperuser loses their superuser privileges but still owns a\\nsubscription. But perhaps we can solve that a different way, like just\\nperforming a check when someone loses their superuser privileges that\\nthey don't own any subscriptions.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 09:33:24 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> I am still trying to understand this use case. It doesn't feel like\\n> \\\"ownership\\\" to me, it feels more like some kind of delegation.\\n> \\n> Is GRANT a better fit here? That would allow more than one user to\\n> REFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\\n> RENAME, but I don't see why we'd separate privileges for\\n> CREATE/DROP/RENAME anyway.\\n\\nWe may eventually allow non-superusers to create subscriptions, but there are lots of details to work out. Should there be limits on how many subscriptions they can create? Should there be limits to the number of simultaneously open connections they can create out to other database servers (publishers)? Should they need to be granted USAGE on a database publisher in order to use the connection string for that publisher in a subscription they create? Should they need to be granted USAGE on a publication in order to replicate it? Yes, there may be restrictions on the publisher side, too, but the user model on subscriber and publisher might differ, and the connection string used might not match the subscription owner, so some restriction on the subscriber side may be needed.\\n\\nThe implementation of [CREATE | ALTER] SUBSCRIPTION was designed at a time when only superusers could execute them, and as far as I can infer from the design, no effort to constrain the effects of those commands was made. Since we're trying to make subscriptions into things that non-superusers can use, we have to deal with some things in those functions. For example, ALTER SUBSCRIPTION can change the database connection parameter, or the publication subscribed, or whether synchronous_commit is used. I don't see that a subscription owner should necessarily be allowed to mess with that, at least not without some other privilege checks beyond mere ownership.\\n\\nI think this is pretty analogous to how security definer functions work. You might call those \\\"delegation\\\" also, but the basic idea is that the function will run under the privileges of the function's owner, who might be quite privileged if you want the function to do highly secure things for you, but who could also intentionally be limited in privilege. It wouldn't make much sense to say the owner of a security definer function can arbitrarily escalate their privileges to do things like open connections to other database servers, or have the transactions in which they run have a different setting of synchronous_commit. Yet with subscriptions, if the subscription owner can run all forms of ALTER SUBSCRIPTION, that's what they can do.\\n\\nI took a conservative position in the design of the patch to avoid giving away too much. I suspect that we'll come back to these design decisions and relax them at some point, but the exact way in which we relax them is not obvious. We could just agree to remove them (as you seem to propose), or we might agree to create predefined roles and say that the subscription owner can change certain aspects of the subscription if and only if they are members of one or more of those roles, or we may create new grantable privileges. Each of those debates may be long and hard fought, so I don't want to invite that as part of this thread, or this patch will almost surely miss the cutoff for v15.\\n\\n> This would not address the weirdness of the existing code where a\\n> superuser loses their superuser privileges but still owns a\\n> subscription. But perhaps we can solve that a different way, like just\\n> performing a check when someone loses their superuser privileges that\\n> they don't own any subscriptions.\\n\\nI gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 10:25:50 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> Is GRANT a better fit here? That would allow more than one user to\\n> REFRESH, or ENABLE/DISABLE the same subscription. It wouldn't allow\\n> RENAME, but I don't see why we'd separate privileges for\\n> CREATE/DROP/RENAME anyway.\\n\\nI don't think I answered this directly in my last reply.\\n\\nGRANT *might* be part of some solution, but it is unclear to me how best to do it. The various configuration parameters on subscriptions entail different security concerns. We might take a fine-grained approach and create a predefined role for each, or we might take a course-grained approach and create a single pg_manage_subscriptions role which can set any parameter on any subscription, or maybe just parameters on subscriptions that the role also owns, or we might do something else, like burn some privilege bits and define new privileges that can be granted per subscription rather than globally. (I think that last one is a non-starter, but just mention it as an example of another approach.)\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 10:48:44 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 11/16/21 15:06, Andrew Dunstan wrote:\\n> On 11/3/21 15:50, Mark Dilger wrote:\\n>>> On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n>>>\\n>>> ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n>> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record. I think that is consistent enough with reasonable expectations.\\n>>\\n>> The first two patches are virtually unchanged. The third updates the behavior of the apply workers, and updates the documentation to match.\\n>\\n> I'm generally happier about this than the previous patch set. With the\\n> exception of some slight documentation modifications I think it's\\n> basically committable. There doesn't seem to be a CF item for it but I'm\\n> inclined to commit it in a couple of days time.\\n>\\n>\\n\\nGiven there is some debate about the patch set I will hold off any\\naction for the time being.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 15:26:41 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 10:25 -0800, Mark Dilger wrote:\\n> We may eventually allow non-superusers to create subscriptions, but\\n> there are lots of details to work out.\\n\\nI am setting aside the idea of subscriptions created by non-superusers.\\n\\nMy comments were about your idea for \\\"low-power users\\\" that can still\\ndo things with subscriptions. And for that, GRANT seems like a better\\nfit than ownership.\\n\\nWith v2-0001, there are several things that seem weird to me:\\n\\n * Why can there be only one low-power user per subscription?\\n * Why is RENAME a separate capability from CREATE/DROP?\\n * What if you want to make the privileges more fine-grained, or make\\nchanges in the future? Ownership is a single bit, so it requires that\\neveryone agree. Maybe some people want RENAME to be a part of that, and\\nothers don't.\\n\\nGRANT seems to provide better answers here.\\n\\n> Since we're trying to make subscriptions into things that non-\\n> superusers can use, we have to deal with some things in those\\n> functions.\\n\\nI understand the use case where a superuser isn't required anywhere in\\nthe process, and some special users can create and own subscriptions. I\\nalso understand that's not what these patches are trying to accomplish\\n(though v2-0003 seems like a good step in that direction).\\n\\nI don't understand the use case as well where a non-superuser can\\nmerely \\\"use\\\" a subscription. I'm sure such use cases exist and I'm fine\\nto go along with that idea, but I'd like to understand why ownership\\n(partial ownership?) is the right way to do this and GRANT is the wrong\\nway.\\n\\n> For example, ALTER SUBSCRIPTION can change the database connection\\n> parameter, or the publication subscribed, or whether\\n> synchronous_commit is used. I don't see that a subscription owner\\n> should necessarily be allowed to mess with that, at least not without\\n> some other privilege checks beyond mere ownership.\\n\\nThat violates my expectations of what \\\"ownership\\\" means.\\n\\n> I think this is pretty analogous to how security definer functions\\n> work.\\n\\nThe analogy to SECURITY DEFINER functions seems to support my\\nsuggestion for GRANT at least as much as your modified definition of\\nownership.\\n\\n> > This would not address the weirdness of the existing code where a\\n> > superuser loses their superuser privileges but still owns a\\n> > subscription. But perhaps we can solve that a different way, like\\n> > just\\n> > performing a check when someone loses their superuser privileges\\n> > that\\n> > they don't own any subscriptions.\\n> \\n> I gave that a slight amount of thought during the design of this\\n> patch, but didn't think we could refuse to revoke superuser on such a\\n> basis,\\n\\nI don't necessarily see a problem there, but I could be missing\\nsomething.\\n\\n> and didn't see what we should do with the subscription other than\\n> have it continue to be owned by the recently-non-superuser. If you\\n> have a better idea, we can discuss it, but to some degree I think\\n> that is also orthogonal to the purpose of this patch. The only sense\\n> in which this patch depends on that issue is that this patch proposes\\n> that non-superuser subscription owners are already an issue, and\\n> therefore that this patch isn't creating a new issue, but rather\\n> making more sane something that already can happen.\\n\\nBy introducing and documenting a way to get non-superusers to own a\\nsubscription, it makes it more likely that people will do it, and\\nharder for us to change. That means the standard should be \\\"this is\\nwhat we really want\\\", rather than just \\\"more sane than before\\\".\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 13:06:32 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 10:48 -0800, Mark Dilger wrote:\\n> GRANT *might* be part of some solution, but it is unclear to me how\\n> best to do it. The various configuration parameters on subscriptions\\n> entail different security concerns. We might take a fine-grained\\n> approach and create a predefined role for each\\n\\nI think you misunderstood the idea: not using predefined roles, just\\nplain old ordinary GRANT on a subscription object to ordinary roles.\\n\\n GRANT REFRESH ON SUBSCRIPTION sub1 TO nonsuper;\\n\\nThis should be easy enough because the subscription is a real object,\\nright?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 13:10:20 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 17, 2021, at 1:10 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> I think you misunderstood the idea: not using predefined roles, just\\n> plain old ordinary GRANT on a subscription object to ordinary roles.\\n> \\n> GRANT REFRESH ON SUBSCRIPTION sub1 TO nonsuper;\\n> \\n> This should be easy enough because the subscription is a real object,\\n> right?\\n\\n/*\\n * Grantable rights are encoded so that we can OR them together in a bitmask.\\n * The present representation of AclItem limits us to 16 distinct rights,\\n * even though AclMode is defined as uint32. See utils/acl.h.\\n *\\n * Caution: changing these codes breaks stored ACLs, hence forces initdb.\\n */\\ntypedef uint32 AclMode; /* a bitmask of privilege bits */\\n\\n#define ACL_INSERT (1<<0) /* for relations */\\n#define ACL_SELECT (1<<1)\\n#define ACL_UPDATE (1<<2)\\n#define ACL_DELETE (1<<3)\\n#define ACL_TRUNCATE (1<<4)\\n#define ACL_REFERENCES (1<<5)\\n#define ACL_TRIGGER (1<<6)\\n#define ACL_EXECUTE (1<<7) /* for functions */\\n#define ACL_USAGE (1<<8) /* for languages, namespaces, FDWs, and\\n * servers */\\n#define ACL_CREATE (1<<9) /* for namespaces and databases */\\n#define ACL_CREATE_TEMP (1<<10) /* for databases */\\n#define ACL_CONNECT (1<<11) /* for databases */\\n\\n\\nWe only have 4 values left in the bitmask, and I doubt that burning those slots for multiple new types of rights that only have meaning for subscriptions is going to be accepted. For full disclosure, I'm proposing adding ACL_SET and ACL_ALTER_SYSTEM in another patch and my proposal there could get shot down for the same reasons, but I think your argument would be even harder to defend. Maybe others feel differently.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 15:07:10 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 15:07 -0800, Mark Dilger wrote:\\n> We only have 4 values left in the bitmask, and I doubt that burning\\n> those slots for multiple new types of rights that only have meaning\\n> for subscriptions is going to be accepted. For full disclosure, I'm\\n> proposing adding ACL_SET and ACL_ALTER_SYSTEM in another patch and my\\n> proposal there could get shot down for the same reasons, but I think\\n> your argument would be even harder to defend. Maybe others feel\\n> differently.\\n\\nWhy not overload ACL_USAGE again, and say:\\n\\n GRANT USAGE ON SUBSCRIPTION sub1 TO nonsuper;\\n\\nwould allow ENABLE/DISABLE and REFRESH.\\n\\nAgain, I don't really understand the use case behind \\\"can use a\\nsubscription but not create one\\\", so I'm not making a proposal. But\\nassuming that the use case exists, GRANT seems like a much better\\napproach.\\n\\n(Aside: for me to commit something like this I'd want to understand the\\n\\\"can use a subscription but not create one\\\" use case better.)\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 15:46:55 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 17, 2021, at 1:06 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> On Wed, 2021-11-17 at 10:25 -0800, Mark Dilger wrote:\\n>> We may eventually allow non-superusers to create subscriptions, but\\n>> there are lots of details to work out.\\n> \\n> I am setting aside the idea of subscriptions created by non-superusers.\\n\\nOk, fair enough. I think eventually we'll want that, but I'm also setting that aside for this patch.\\n\\n> My comments were about your idea for \\\"low-power users\\\" that can still\\n> do things with subscriptions. And for that, GRANT seems like a better\\n> fit than ownership.\\n\\nThis patch has basically no value beyond the fact that it allows the replication to be *applied* as a user other than superuser. Throw that out, and there isn't any point. Everything else is window dressing. The real security problem with subscriptions is that they act with superuser power. That naturally means that they must be owned and operated by superuser, too, otherwise they serve as a privilege escalation attack vector. It really doesn't make any sense to think of subscriptions as operating under the permissions of multiple non-superusers. You must choose a single role you want the subscription to run under. What purpose would be served by GRANTing privileges on a subscription to more than one non-superuser? It still operates as just the one user. I agree you *could* give multiple users privileges to mess with it, but you'd still need to assign a single role as the one whose privileges matter for the purpose of applying replication changes. I'm using \\\"owner\\\" for that purpose, and I think that is consistent with how security definer functions work. They run as the owner, too. It's perfectly well-precedented to use \\\"owner\\\" for this.\\n\\nI think the longer term plan is that non-superusers who have some privileged role will be allowed to create subscriptions, and naturally they will own the subscriptions that they create, at least until an ALTER SUBSCRIPTION..OWNER TO is successfully executed to transfer ownership. Once that longer term plan is complete, non-superusers will be able to create publications of their tables on one database, and subscriptions to those publications on another database, all without needing the help of a superuser. This patch doesn't get us all the way there, but it heads directly toward that goal.\\n\\n> With v2-0001, there are several things that seem weird to me:\\n> \\n> * Why can there be only one low-power user per subscription?\\n\\nBecause the apply workers run as only one user. Currently it is always superuser. After this patch, it is always the owner, which amounts to the same thing for legacy subscriptions created and owned by superuser prior to upgrading to v15, but not necessarily for new ones or ones that have ownership transferred after upgrade.\\n\\nWe could think about subscriptions that act under multiple roles, perhaps taking role information as part of the data-stream from the publisher, but that's a pretty complicated proposal, and it is far from clear that we want it anyway. There is a security case to be made for *not* allowing the publisher to call all the shots, so such a proposal would at best be an alternate mode of operation, not the one and only mode.\\n\\n> * Why is RENAME a separate capability from CREATE/DROP?\\n\\nI don't care enough to argue this point. If you want me to remove RENAME privilege from the owner, I can resubmit with it removed. It just doesn't seem like it's dangerous to allow a non-superuser to rename their subscriptions, so I saw no compelling reason to disallow it.\\n\\nCREATE clearly must be disallowed since it gives the creator the ability to form network connections, set fsync modes, etc., and there is no reason to assume arbitrary non-superusers should be able to do that.\\n\\nThe argument against DROP is a bit weaker. It doesn't seem like a user who cannot bring subscriptions into existence should be able to drop them either. I was expecting to visit that issue in a follow-on patch which deals with non-superuser predefined roles that have some power to create and drop subscriptions. What that patch will propose to do is not obvious, since some of what you can do with subscriptions is so powerful we may not want non-superusers doing it, even with a privileged role. If you can't picture what I mean, consider that you might use a connection parameter that connects outside and embeds data into the connection string, with a server listening on the other end, not really to publish data, but to harvest the secret data that you are embedding in the network connection attempt.\\n\\n> * What if you want to make the privileges more fine-grained, or make\\n> changes in the future? Ownership is a single bit, so it requires that\\n> everyone agree.\\n\\nWe can modify the patch to have the subscription owner have zero privileges on the subscription, not even the ability to see how it is defined, and just have \\\"owner\\\" mean the role under whose privileges the logical replication workers apply changes. Would that be better? I would expect people to find that odd.\\n\\nThe problem is that we want a setuid/setgid type behavior. Actual setuid/setgid programs act as the user/group of the executable. There's no reason that user/group needs to be one that any real human uses to log into the system. Likewise, we need the subscription to act under a role, and we're establishing which role that is by having that role own the subscription. That is like how setuid/setgid programs work by executing as the user/group that owns the executable, except that postgres doesn't have separate user/group concepts, just roles. Isn't this design pattern completely commonplace?\\n\\n> Maybe some people want RENAME to be a part of that, and\\n> others don't.\\n\\nFair enough. Should I remove RENAME from what the patch allows the owner to do? On this particular point, I genuinely don't care. I think it can be reasonably argued either way.\\n\\n> GRANT seems to provide better answers here.\\n\\nNo, because we don't have infinite privilege bits to burn.\\n\\n>> Since we're trying to make subscriptions into things that non-\\n>> superusers can use, we have to deal with some things in those\\n>> functions.\\n> \\n> I understand the use case where a superuser isn't required anywhere in\\n> the process, and some special users can create and own subscriptions. I\\n> also understand that's not what these patches are trying to accomplish\\n> (though v2-0003 seems like a good step in that direction).\\n\\nThere is a cart-before-the-horse problem here. If I propose a patch with a privileged role for creating and owning subscriptions *before* I tighten down how non-superuser-owned subscriptions work, that patch would surely be rejected. So I either propose this first, and only if/when it gets accepted, propose the other, or I propose them together. That's a damned-if-you-do--damned-if-you-dont situation, because if I propose them together, I'll get arguments that they are clearly separable and should be proposed separately, and if I do them one before the other, I'll get the argument that you are making now. I fully expect the privileged role proposal to be made (possibly by me), though it is unclear if there will be time left to do it in v15.\\n\\n> I don't understand the use case as well where a non-superuser can\\n> merely \\\"use\\\" a subscription. I'm sure such use cases exist and I'm fine\\n> to go along with that idea, but I'd like to understand why ownership\\n> (partial ownership?) is the right way to do this and GRANT is the wrong\\n> way.\\n\\nEven if we had the privilege bits to burn, no spelling of that GRANT idea sounds all that great:\\n\\n\\tGRANT RUN AS ON subscription TO role;\\n\\tGRANT RUN AS ON role TO subscription;\\n\\tGRANT SUDO ON subscription TO role;\\n\\tGRANT SETUID ON role TO subscription;\\n\\t...\\n\\nI just don't see how that really works. I'm not inclined to spend time being more clever, since I already know that privilege bits are in short supply, but if you want to propose something, go ahead. Elsewhere you proposed GRANT REFRESH or something, not looking at that email just now, but that's not the same thing as GRANT RUN AS, and burns another privilege bit, and still doesn't get us all the way there, because you presumably also want GRANT RENAME, GRANT ALTER CONNECTION SETTING, GRANT ALTER FSYNC SETTING, ..., and we're out of privilege bits before we're done.\\n\\n>> For example, ALTER SUBSCRIPTION can change the database connection\\n>> parameter, or the publication subscribed, or whether\\n>> synchronous_commit is used. I don't see that a subscription owner\\n>> should necessarily be allowed to mess with that, at least not without\\n>> some other privilege checks beyond mere ownership.\\n> \\n> That violates my expectations of what \\\"ownership\\\" means.\\n\\nI think that's because you're thinking of these settings as properties of the subscription. You may *own* the subscription, but the subscription doesn't *own* the right to make connections to arbitrary databases, nor *own* the right to change buffer cache settings, nor *own* the right to bring data from a publication on some other server which, if it existed on the local server, would violate site policy and possibly constitute a civil or criminal violation of data privacy laws. I may own my house, and the land it sits on, and my driveway, but that doesn't mean I own the ability to make my driveway go across my neighbor's field, down through town, and to the waterfront. But that's the kind of ownership definition you seem to be defending.\\n\\nSome of what I perceive as the screwiness of your argument I must admin is not your fault. The properties of subscriptions are defined in ways that don't make sense to me. It would be far more sensible if connection strings were objects in their own right, and you could grant USAGE on a connection string to a role, and USAGE on a subscription to a role, and only if the subscription worker's role had privileges on the connection string could they use it as part of fulfilling their task of replicating the data, and otherwise they'd error out in the attempt. Likewise, fsync modes could be proper objects, and only if the subscription's role had privileges on the fsync mode they wanted to use would they be able to use it. But we don't have these things as proper objects, with acl lists on them, so we're stuck trying to design around that. To my mind, that means subscription owners *do not own* properties associated with the subscription. To your mind, that's not what \\\"ownership\\\" means. What to do?\\n\\n>> I think this is pretty analogous to how security definer functions\\n>> work.\\n> \\n> The analogy to SECURITY DEFINER functions seems to support my\\n> suggestion for GRANT at least as much as your modified definition of\\n> ownership.\\n\\nI don't see how. Can you please explain?\\n\\n>>> This would not address the weirdness of the existing code where a\\n>>> superuser loses their superuser privileges but still owns a\\n>>> subscription. But perhaps we can solve that a different way, like\\n>>> just\\n>>> performing a check when someone loses their superuser privileges\\n>>> that\\n>>> they don't own any subscriptions.\\n>> \\n>> I gave that a slight amount of thought during the design of this\\n>> patch, but didn't think we could refuse to revoke superuser on such a\\n>> basis,\\n> \\n> I don't necessarily see a problem there, but I could be missing\\n> something.\\n\\nClose your eyes and imagine that I have superuser on your database... really picture it in your mind. Now, do you want the revoke command you are issuing to work?\\n\\n>> and didn't see what we should do with the subscription other than\\n>> have it continue to be owned by the recently-non-superuser. If you\\n>> have a better idea, we can discuss it, but to some degree I think\\n>> that is also orthogonal to the purpose of this patch. The only sense\\n>> in which this patch depends on that issue is that this patch proposes\\n>> that non-superuser subscription owners are already an issue, and\\n>> therefore that this patch isn't creating a new issue, but rather\\n>> making more sane something that already can happen.\\n> \\n> By introducing and documenting a way to get non-superusers to own a\\n> subscription, it makes it more likely that people will do it, and\\n> harder for us to change. That means the standard should be \\\"this is\\n> what we really want\\\", rather than just \\\"more sane than before\\\".\\n\\nOk, I'll wait to hear back from you on the points above.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Nov 2021 16:17:42 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Nov 17, 2021 at 11:56 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Nov 17, 2021, at 9:33 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> >\\n>\\n> > This would not address the weirdness of the existing code where a\\n> > superuser loses their superuser privileges but still owns a\\n> > subscription. But perhaps we can solve that a different way, like just\\n> > performing a check when someone loses their superuser privileges that\\n> > they don't own any subscriptions.\\n>\\n> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\\n>\\n\\nDon't we want to close this gap irrespective of the other part of the\\nfeature? I mean if we take out the part of your 0003 patch that checks\\nwhether the current user has permission to perform a particular\\noperation on the target table then the gap related to the owner losing\\nsuperuser privileges should be addressed.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 16:20:01 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 4, 2021 at 1:20 AM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Nov 1, 2021, at 10:58 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> >\\n> > ALTER SUBSCRIPTION..[ENABLE | DISABLE] do not synchronously start or stop subscription workers. The ALTER command updates the catalog's subenabled field, but workers only lazily respond to that. Disabling and enabling the subscription as part of the OWNER TO would not reliably accomplish anything.\\n>\\n> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record.\\n>\\n\\nAre you talking about the below change in the above paragraph?\\n\\n@@ -2912,6 +2941,7 @@ maybe_reread_subscription(void)\\n strcmp(newsub->slotname, MySubscription->slotname) != 0 ||\\n newsub->binary != MySubscription->binary ||\\n newsub->stream != MySubscription->stream ||\\n+ newsub->owner != MySubscription->owner ||\\n !equal(newsub->publications, MySubscription->publications))\\n {\\n\\nIf so, I am not sure how it will ensure that we check the ownership\\nchange before applying each change? I think this will be invoked at\\neach transaction boundary, so, if there is a transaction with a large\\nnumber of changes, all the changes will be processed under the\\nprevious owner.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 17:07:47 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 18, 2021, at 2:50 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n>> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\\n>> \\n> \\n> Don't we want to close this gap irrespective of the other part of the\\n> feature? I mean if we take out the part of your 0003 patch that checks\\n> whether the current user has permission to perform a particular\\n> operation on the target table then the gap related to the owner losing\\n> superuser privileges should be addressed.\\n\\nI don't think there is a gap. The patch does the right thing, causing the subscription whose owner has had superuser revoked to itself no longer function with superuser privileges. Whether that causes the subscription to fail depends on whether the previously-superuser now non-superuser owner now lacks sufficient privileges on the target relation(s). I think removing that part of the patch would be a regression.\\n\\nLet's compare two scenarios. In the first, we have a regular user \\\"alice\\\" who owns a subscription which replicates into table \\\"accounting.receipts\\\" for which she has been granted privileges by the table's owner. What would you expect to happen after the table's owner revokes privileges from alice? I would expect that the subscription can no longer function, and periodic attempts to replicate into that table result in permission denied errors in the logs.\\n\\nIn the second, we have a superuser \\\"alice\\\" who owns a subscription that replicates into table \\\"accounting.receipts\\\", and she only has sufficient privileges to modify \\\"accounting.receipts\\\" by virtue of being superuser. I would expect that when she has superuser revoked, the subscription can likewise no longer function. \\n\\nNow, maybe I'm wrong in both cases, and both should continue to function. But I would find it really strange if the first situation behaved differently from the second.\\n\\nI think intuitions about how subscriptions behave differ depending on the reason you expect the subscription to be owned by a particular user. If the reason the user owns the subscription is that the user just happens to be the user who created it, but isn't in your mind associated with the subscription, then having the subscription continue to function regardless of what happens to the user, even the user being dropped, is probably consistent with your expectations. In a sense, you think of the user who creates the subscription as having gifted it to the universe rather than continuing to own it. Or perhaps you think of the creator of the subscription as a solicitor/lawyer/agent working on behalf of client, and once that legal transaction is completed, you don't expect the lawyer being disbarred should impact the subscription which exists for the benefit of the client.\\n\\nIf instead you think about the subscription owner as continuing to be closely associated with the subscription (as I do), then you expect changes in the owner's permissions to impact the subscription.\\n\\nI think the \\\"gifted to the universe\\\"/\\\"lawyer\\\" mental model is not consistent with how the system is already designed to work. You can't drop the subscription's owner without first running REASSIGN OWNED, or ALTER SUBSCRIPTION..OWNER TO, or simply dropping the subscription:\\n\\n DROP ROLE regress_subscription_user;\\n ERROR: role \\\"regress_subscription_user\\\" cannot be dropped because some objects depend on it\\n DETAIL: owner of subscription regress_testsub\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 07:33:53 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 18, 2021, at 3:37 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n>> I have rethought my prior analysis. The problem in the previous patch was that the subscription apply workers did not check for a change in ownership the way they checked for other changes, instead only picking up the new ownership information when the worker restarted for some other reason. This next patch set fixes that. The application of a change record may continue under the old ownership permissions when a concurrent command changes the ownership of the subscription, but the worker will pick up the new permissions before applying the next record.\\n>> \\n> \\n> Are you talking about the below change in the above paragraph?\\n> \\n> @@ -2912,6 +2941,7 @@ maybe_reread_subscription(void)\\n> strcmp(newsub->slotname, MySubscription->slotname) != 0 ||\\n> newsub->binary != MySubscription->binary ||\\n> newsub->stream != MySubscription->stream ||\\n> + newsub->owner != MySubscription->owner ||\\n> !equal(newsub->publications, MySubscription->publications))\\n> {\\n> \\n> If so, I am not sure how it will ensure that we check the ownership\\n> change before applying each change? I think this will be invoked at\\n> each transaction boundary, so, if there is a transaction with a large\\n> number of changes, all the changes will be processed under the\\n> previous owner.\\n\\nYes, your analysis appears correct. I was sloppy to say \\\"before applying the next record\\\". It will pick up the change before applying the next transaction.\\n\\nThe prior version of the patch only picked up the change if it happened to start a new worker, but could process multiple transactions without noticing the change. Now, it is limited to finishing the current transaction. Would you prefer that the worker noticed the change in ownership and aborted the transaction on the subscriber side? Or should the ALTER SUBSCRIPTION..OWNER TO block? I don't see much advantage to either of those options, but I also don't think I have any knock-down argument for my approach either. What do you think?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 07:45:13 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\\n> You must choose a single role you want the subscription to run\\n> under.\\n\\nI think that was the source of a lot of my confusion: \\n\\nYour patches are creating the notion of a \\\"run as\\\" user by assigning\\nownership-that-isn't-really-ownership. I got distracted wondering why\\nyou would really care if some user could enable/disable/refresh/rename\\na subscription, but the main point was to change who the subscription\\nruns as.\\n\\nThat's a more general idea: I could see how \\\"run as\\\" could apply to\\nsubscriptions as well as functions (right now it can only run as the\\nowner or the invoker, not an arbitrary role). And I better understand\\nyour analogy to security definer now.\\n\\nBut it's also not exactly a simple idea, and I think the current\\npatches oversimplify it and conflate it with ownership. \\n\\n> I think the longer term plan is that non-superusers who have some\\n> privileged role will be allowed to create subscriptions,\\n\\nYou earlier listed some challenges with that:\\n\\n\\nhttps://postgr.es/m/CF56AC0D-7495-4E8D-A48F-FF38BD8074EB@enterprisedb.com\\n\\nBut it seems like it's really the right direction to go. Probably the\\nbiggest concern is connection strings that read server files, but\\ndblink solved that by requiring password auth.\\n\\nWhat are the reasonable steps to get there? Do you think anything is\\ndoable for v15?\\n\\n> There is a cart-before-the-horse problem here.\\n\\nI don't think we need to hold up v2-0003. It seems like a step in the\\nright direction, though I haven't looked closely yet.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 10:29:26 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\\n> Some of what I perceive as the screwiness of your argument I must\\n> admin is not your fault. The properties of subscriptions are defined\\n> in ways that don't make sense to me. It would be far more sensible\\n> if connection strings were objects in their own right, and you could\\n> grant USAGE on a connection string to a role,\\n\\nWe sort of have that with CREATE SERVER, in fact dblink can use a\\nserver instead of a string. \\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 10:50:29 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 18, 2021 at 9:03 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Nov 18, 2021, at 2:50 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >\\n> >> I gave that a slight amount of thought during the design of this patch, but didn't think we could refuse to revoke superuser on such a basis, and didn't see what we should do with the subscription other than have it continue to be owned by the recently-non-superuser. If you have a better idea, we can discuss it, but to some degree I think that is also orthogonal to the purpose of this patch. The only sense in which this patch depends on that issue is that this patch proposes that non-superuser subscription owners are already an issue, and therefore that this patch isn't creating a new issue, but rather making more sane something that already can happen.\\n> >>\\n> >\\n> > Don't we want to close this gap irrespective of the other part of the\\n> > feature? I mean if we take out the part of your 0003 patch that checks\\n> > whether the current user has permission to perform a particular\\n> > operation on the target table then the gap related to the owner losing\\n> > superuser privileges should be addressed.\\n>\\n> I don't think there is a gap. The patch does the right thing, causing the subscription whose owner has had superuser revoked to itself no longer function with superuser privileges. Whether that causes the subscription to fail depends on whether the previously-superuser now non-superuser owner now lacks sufficient privileges on the target relation(s). I think removing that part of the patch would be a regression.\\n>\\n\\nI think we are saying the same thing. I intend to say that your 0003*\\npatch closes the current gap in the code and we should consider\\napplying it irrespective of what we do with respect to changing the\\n... OWNER TO .. behavior. Is there a reason why 0003* patch (or\\nsomething on those lines) shouldn't be considered to be applied?\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 15:14:40 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 18, 2021 at 9:15 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> The prior version of the patch only picked up the change if it happened to start a new worker, but could process multiple transactions without noticing the change. Now, it is limited to finishing the current transaction. Would you prefer that the worker noticed the change in ownership and aborted the transaction on the subscriber side? Or should the ALTER SUBSCRIPTION..OWNER TO block? I don't see much advantage to either of those options, but I also don't think I have any knock-down argument for my approach either. What do you think?\\n>\\n\\nHow about allowing to change ownership only for disabled\\nsubscriptions? Basically, users need to first disable the subscription\\nand then change its ownership. Now, disabling is an asynchronous\\noperation but we won't allow the ownership change command to proceed\\nunless the subscription is marked disabled and all the apply/sync\\nworkers are not running. After the ownership is changed, users can\\nenable it. We already have 'slot_name' parameter's dependency on\\nwhether the subscription is marked enabled or not.\\n\\nThis will add some steps in changing the ownership of a subscription\\nbut I think it will be predictable.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 15:26:09 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Nov 19, 2021 at 12:00 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Wed, 2021-11-17 at 16:17 -0800, Mark Dilger wrote:\\n> > You must choose a single role you want the subscription to run\\n> > under.\\n>\\n> I think that was the source of a lot of my confusion:\\n>\\n> Your patches are creating the notion of a \\\"run as\\\" user by assigning\\n> ownership-that-isn't-really-ownership. I got distracted wondering why\\n> you would really care if some user could enable/disable/refresh/rename\\n> a subscription, but the main point was to change who the subscription\\n> runs as.\\n>\\n> That's a more general idea: I could see how \\\"run as\\\" could apply to\\n> subscriptions as well as functions (right now it can only run as the\\n> owner or the invoker, not an arbitrary role). And I better understand\\n> your analogy to security definer now.\\n>\\n\\nI was thinking why not separate the ownership and \\\"run as\\\" privileges\\nfor the subscriptions? We can introduce a new syntax in addition to\\nthe current syntax for \\\"Owner\\\" for this as:\\n\\nCreate Subscription sub RUNAS <role_name> ...;\\nAlter Subscription sub RUNAS <role_name>\\n\\nNow, RUNAS role will be used to apply changes and perform the initial\\ntable sync. The owner will be tied to changing some of the other\\nproperties (enabling, disabling, etc.) of the subscription. Now, we\\nstill need a superuser to create subscription and change properties\\nlike CONNECTION for a subscription but we can solve that by having\\nroles specific to it as being indicated by Mark in some of his\\nprevious emails.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 15:53:08 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 19, 2021, at 1:44 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> I think we are saying the same thing. I intend to say that your 0003*\\n> patch closes the current gap in the code and we should consider\\n> applying it irrespective of what we do with respect to changing the\\n> ... OWNER TO .. behavior. Is there a reason why 0003* patch (or\\n> something on those lines) shouldn't be considered to be applied?\\n\\nJeff Davis and I had a long conversation off-list yesterday and reached the same conclusion. I will be submitting a version of 0003 which does not depend on the prior two patches.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 07:25:49 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 19, 2021, at 1:56 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> How about allowing to change ownership only for disabled\\n> subscriptions? Basically, users need to first disable the subscription\\n> and then change its ownership.\\n\\nThere are some open issues about non-superuser owners that Jeff would like to address before allowing transfers of ownership to non-superusers. Your proposal about requiring the subscription to be disabled seems reasonable to me, but I'd like to see how it would interact with whatever Jeff proposes. So I think I will change the patch as you suggest, but consider it a WIP patch until then.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 07:47:06 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 19, 2021, at 2:23 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> I was thinking why not separate the ownership and \\\"run as\\\" privileges\\n> for the subscriptions? We can introduce a new syntax in addition to\\n> the current syntax for \\\"Owner\\\" for this as:\\n> \\n> Create Subscription sub RUNAS <role_name> ...;\\n> Alter Subscription sub RUNAS <role_name>\\n> \\n> Now, RUNAS role will be used to apply changes and perform the initial\\n> table sync. The owner will be tied to changing some of the other\\n> properties (enabling, disabling, etc.) of the subscription. Now, we\\n> still need a superuser to create subscription and change properties\\n> like CONNECTION for a subscription but we can solve that by having\\n> roles specific to it as being indicated by Mark in some of his\\n> previous emails.\\n\\nI feel disquieted about the \\\"runas\\\" idea. I can't really say why yet. Maybe it is ok, but it feels like a larger design decision than just an implementation detail about how subscriptions work. We should consider if we won't soon be doing the same thing for other parts of the system. If so, we should choose a solution that makes sense when applied more broadly.\\n\\nSecurity definer functions could benefit from splitting the owner from the runas role.\\n\\nEvent triggers might benefit from having a runas role. Currently, event triggers are always owned by superusers, but we've discussed allowing non-superuser owners. That proposal still has outstanding issues to be resolved, so I can't be sure if runas would be helpful, but it might.\\n\\nTable triggers might benefit from having a runas role. I don't have a proposal here, just an intuition that we should think about this before designing how \\\"runas\\\" works.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Nov 2021 08:12:27 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"> On Nov 19, 2021, at 7:25 AM, Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> \\n> Jeff Davis and I had a long conversation off-list yesterday and reached the same conclusion. I will be submitting a version of 0003 which does not depend on the prior two patches.\\n\\nRenamed as 0001 in version 3, as it is the only remaining patch. For anyone who reviewed the older patch set, please note that I made some changes to the src/test/subscription/t/026_nosuperuser.pl test case relative to the prior version.\\n\\n\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Fri, 19 Nov 2021 16:45:50 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, 2021-11-19 at 16:45 -0800, Mark Dilger wrote:\\n> Renamed as 0001 in version 3, as it is the only remaining patch. For\\n> anyone who reviewed the older patch set, please note that I made some\\n> changes to the src/test/subscription/t/026_nosuperuser.pl test case\\n> relative to the prior version.\\n\\nWe need to do permission checking for WITH CHECK OPTION and RLS. The\\npatch right now allows the subscription to write data that an RLS\\npolicy forbids.\\n\\nA couple other points:\\n\\n * We shouldn't refer to the behavior of previous versions in the docs\\nunless there's a compelling reason\\n * Do we need to be smarter about partitioned tables, where an insert\\ncan turn into an update?\\n * Should we refactor to borrow logic from ExecInsert so that it's less\\nlikely that we miss something in the future?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 24 Nov 2021 16:30:06 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 25, 2021 at 6:00 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Fri, 2021-11-19 at 16:45 -0800, Mark Dilger wrote:\\n> > Renamed as 0001 in version 3, as it is the only remaining patch. For\\n> > anyone who reviewed the older patch set, please note that I made some\\n> > changes to the src/test/subscription/t/026_nosuperuser.pl test case\\n> > relative to the prior version.\\n>\\n> We need to do permission checking for WITH CHECK OPTION and RLS. The\\n> patch right now allows the subscription to write data that an RLS\\n> policy forbids.\\n>\\n\\nWon't it be better to just check if the current user is superuser\\nbefore applying each change as a matter of this first patch? Sorry, I\\nwas under impression that first, we want to close the current gap\\nwhere we allow to proceed with replication if the user's superuser\\nprivileges were revoked during replication. To allow non-superusers\\nowners, I thought it might be better to first try to detect the change\\nof ownership as soon as possible instead of at the transaction\\nboundary.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 25 Nov 2021 09:51:22 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2021-11-25 at 09:51 +0530, Amit Kapila wrote:\\n> Won't it be better to just check if the current user is superuser\\n> before applying each change as a matter of this first patch? Sorry, I\\n> was under impression that first, we want to close the current gap\\n> where we allow to proceed with replication if the user's superuser\\n> privileges were revoked during replication.\\n\\nThat could be a first step, and I don't oppose it. But it seems like a\\nvery small first step that would be made obsolete when v3-0001 is\\nready, which I think will be very soon.\\n\\n> To allow non-superusers\\n> owners, I thought it might be better to first try to detect the\\n> change\\n> of ownership\\n\\nIn the case of revoked superuser privileges, there's no change in\\nownership, just a change of privileges (SUPERUSER -> NOSUPERUSER). And\\nif we're detecting a change of privileges, why not just do it in\\nsomething closer to the right way, which is what v3-0001 is attempting\\nto do.\\n\\n> as soon as possible instead of at the transaction\\n> boundary.\\n\\nI don't understand why it's important to detect a loss of privileges\\nfaster than a transaction boundary. Can you elaborate?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 25 Nov 2021 12:06:36 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> We need to do permission checking for WITH CHECK OPTION and RLS. The\\n> patch right now allows the subscription to write data that an RLS\\n> policy forbids.\\n\\nThanks for reviewing and for this observation! I can verify that RLS is not being honored on the subscriber side. I agree this is a problem for subscriptions owned by non-superusers.\\n\\nThe implementation of the table sync worker uses COPY FROM, which makes this problem hard to fix, because COPY FROM does not support row level security. We could do some work to honor the RLS policies during the apply workers' INSERT statements, but then some data would circumvent RLS during table sync and other data would honor RLS during worker apply, which would make the implementation not only wrong but inconsistently so.\\n\\nI think a more sensible approach for v15 is to raise an ERROR if a non-superuser owned subscription is trying to replicate into a table which has RLS enabled. We might try to be more clever and check whether the RLS policies could possibly reject the operation (by comparing the TO and FOR clauses of the policies against the role and operation type) but that seems like a partial re-implementation of RLS. It would be simpler and more likely correct if we just unconditionally reject replicating into tables which have RLS enabled.\\n\\nWhat do you think?\\n\\n> A couple other points:\\n> \\n> * We shouldn't refer to the behavior of previous versions in the docs\\n> unless there's a compelling reason\\n\\nFair enough.\\n\\n> * Do we need to be smarter about partitioned tables, where an insert\\n> can turn into an update?\\n\\nDo you mean an INSERT statement with an ON CONFLICT DO UPDATE clause that is running against a partitioned table? If so, I don't think we need to handle that on the subscriber side under the current logical replication design. I would expect the plain INSERT or UPDATE that ultimately executes on the publisher to be what gets replicated to the subscriber, and not the original INSERT .. ON CONFLICT DO UPDATE statement.\\n\\n> * Should we refactor to borrow logic from ExecInsert so that it's less\\n> likely that we miss something in the future?\\n\\nHooking into the executor at a higher level, possibly ExecInsert or ExecModifyTable would do a lot more than what logical replication currently does. If we also always used INSERT/UPDATE/DELETE statements and never COPY FROM statements, we might solve several problems at once, including honoring RLS policies and honoring rules defined for the target table on the subscriber side.\\n\\nDoing this would clearly be a major design change, and possibly one we do not want. Can we consider this out of scope?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sat, 27 Nov 2021 10:05:16 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Nov 26, 2021 at 1:36 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> > as soon as possible instead of at the transaction\\n> > boundary.\\n>\\n> I don't understand why it's important to detect a loss of privileges\\n> faster than a transaction boundary. Can you elaborate?\\n>\\n\\nThe first reason is that way it would be consistent with what we can\\nsee while doing the operations from the backend. For example, if we\\nrevoke privileges from the user during the transaction, the results\\nwill be reflected.\\npostgres=> Begin;\\nBEGIN\\npostgres=*> insert into t1 values(1);\\nINSERT 0 1\\npostgres=*> insert into t1 values(2);\\nERROR: permission denied for table t1\\n\\nIn this case, after the first insert, I have revoked the privileges of\\nthe user from table t1 and the same is reflected in the very next\\noperation. Another reason is to make behavior predictable as users can\\nalways expect when exactly the privilege change will be reflected and\\nit won't depend on the number of changes in the transaction.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 09:43:41 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Nov 27, 2021 at 11:37 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n>\\n>\\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> >\\n> > We need to do permission checking for WITH CHECK OPTION and RLS. The\\n> > patch right now allows the subscription to write data that an RLS\\n> > policy forbids.\\n>\\n> Thanks for reviewing and for this observation! I can verify that RLS is not being honored on the subscriber side. I agree this is a problem for subscriptions owned by non-superusers.\\n>\\n...\\n>\\n> > A couple other points:\\n> >\\n>\\n> > * Do we need to be smarter about partitioned tables, where an insert\\n> > can turn into an update?\\n>\\n> Do you mean an INSERT statement with an ON CONFLICT DO UPDATE clause that is running against a partitioned table? If so, I don't think we need to handle that on the subscriber side under the current logical replication design. I would expect the plain INSERT or UPDATE that ultimately executes on the publisher to be what gets replicated to the subscriber, and not the original INSERT .. ON CONFLICT DO UPDATE statement.\\n>\\n\\nYeah, that is correct but I think the update case is more relevant\\nhere. In ExecUpdate(), we convert Update to DELETE+INSERT when the\\npartition constraint is failed whereas, on the subscriber-side, it\\nwill simply fail in this case. It is not clear to me how that is\\ndirectly related to this patch but surely it will be a good\\nimprovement on its own and might help if that requires us to change\\nsome infrastructure here like hooking into executor at a higher level.\\n\\n> > * Should we refactor to borrow logic from ExecInsert so that it's less\\n> > likely that we miss something in the future?\\n>\\n> Hooking into the executor at a higher level, possibly ExecInsert or ExecModifyTable would do a lot more than what logical replication currently does. If we also always used INSERT/UPDATE/DELETE statements and never COPY FROM statements, we might solve several problems at once, including honoring RLS policies and honoring rules defined for the target table on the subscriber side.\\n>\\n> Doing this would clearly be a major design change, and possibly one we do not want. Can we consider this out of scope?\\n>\\n\\nI agree that if we want to do all of this then that would require a\\nlot of changes. However, giving an error for RLS-enabled tables might\\nalso be too restrictive. The few alternatives could be that (a) we\\nallow subscription owners to be either have \\\"bypassrls\\\" attribute or\\nthey could be superusers. (b) don't allow initial table_sync for rls\\nenabled tables. (c) evaluate/analyze what is required to allow Copy\\n From to start respecting RLS policies. (d) reject replicating any\\nchanges to tables that have RLS enabled.\\n\\nI see that you are favoring (d) which clearly has merits like lesser\\ncode/design change but not sure if that is the best way forward or we\\ncan do something better than that either by following one of (a), (b),\\n(c), or something less restrictive than (d).\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 11:26:01 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Nov 28, 2021, at 9:56 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> In ExecUpdate(), we convert Update to DELETE+INSERT when the\\n> partition constraint is failed whereas, on the subscriber-side, it\\n> will simply fail in this case. It is not clear to me how that is\\n> directly related to this patch but surely it will be a good\\n> improvement on its own and might help if that requires us to change\\n> some infrastructure here like hooking into executor at a higher level.\\n\\nI would rather get a fix for non-superuser subscription owners committed than expand the scope of work and have this patch linger until the v16 development cycle. This particular DELETE+INSERT problem sounds important but unrelated and out of scope.\\n\\n> I agree that if we want to do all of this then that would require a\\n> lot of changes. However, giving an error for RLS-enabled tables might\\n> also be too restrictive. The few alternatives could be that (a) we\\n> allow subscription owners to be either have \\\"bypassrls\\\" attribute or\\n> they could be superusers. (b) don't allow initial table_sync for rls\\n> enabled tables. (c) evaluate/analyze what is required to allow Copy\\n> From to start respecting RLS policies. (d) reject replicating any\\n> changes to tables that have RLS enabled.\\n> \\n> I see that you are favoring (d) which clearly has merits like lesser\\n> code/design change but not sure if that is the best way forward or we\\n> can do something better than that either by following one of (a), (b),\\n> (c), or something less restrictive than (d).\\n\\nI was favoring option (d) only when RLS policies exist for one or more of the target relations.\\n\\nSkipping the table_sync step while replicating tables that have RLS policies for subscriptions that are owned by users who lack bypassrls is interesting. If we make that work, it will be a more complete solution than option (d).\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 08:26:38 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-29 at 08:26 -0800, Mark Dilger wrote:\\n> > On Nov 28, 2021, at 9:56 PM, Amit Kapila <amit.kapila16@gmail.com>\\n> > wrote:\\n> > \\n> > In ExecUpdate(), we convert Update to DELETE+INSERT when the\\n> > partition constraint is failed whereas, on the subscriber-side, it\\n> > will simply fail in this case.\\n\\nThank you, yes, that's the more important case.\\n\\n> This particular DELETE+INSERT problem sounds important but unrelated\\n> and out of scope.\\n\\n+1\\n\\n> > I agree that if we want to do all of this then that would require a\\n> > lot of changes. However, giving an error for RLS-enabled tables\\n> > might\\n> > also be too restrictive. The few alternatives could be that (a) we\\n> > allow subscription owners to be either have \\\"bypassrls\\\" attribute\\n> > or\\n> > they could be superusers. (b) don't allow initial table_sync for\\n> > rls\\n> > enabled tables. (c) evaluate/analyze what is required to allow Copy\\n> > From to start respecting RLS policies. (d) reject replicating any\\n> > changes to tables that have RLS enabled.\\n\\nMaybe a combination?\\n\\nAllow subscriptions with copy_data=true iff the subscription owner is\\nbypassrls or superuser. And then enforce RLS+WCO during\\ninsert/update/delete.\\n\\nI don't think it's a big change (correct me if I'm wrong), and it\\nallows good functionality now, and room to improve in the future if we\\nwant to bring in more of ExecInsert into logical replication.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 10:22:47 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-29 at 09:43 +0530, Amit Kapila wrote:\\n> The first reason is that way it would be consistent with what we can\\n> see while doing the operations from the backend.\\n\\nLogical replication is not interactive, so it doesn't seem quite the\\nsame.\\n\\nIf you have a long running INSERT INTO SELECT or COPY FROM, the\\npermission checks just happen at the beginning. As a user, it wouldn't\\nsurprise me if logical replication was similar.\\n\\n> operation. Another reason is to make behavior predictable as users\\n> can\\n> always expect when exactly the privilege change will be reflected and\\n> it won't depend on the number of changes in the transaction.\\n\\nThis patch does detect ownership changes more quickly (at the\\ntransaction boundary) than the current code (only when it reloads for\\nsome other reason). Transaction boundary seems like a reasonable time\\nto detect the change to me.\\n\\nDetecting faster might be nice, but I don't have a strong opinion about\\nit and I don't see why it necessarily needs to happen before this patch\\ngoes in.\\n\\nAlso, do you think the cost of doing maybe_reread_subscription() per-\\ntuple instead of per-transaction would be detectable? If we lock\\nourselves into semantics that detect changes quickly, it will be harder\\nto optimize the per-tuple path later.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 11:26:01 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 29, 2021 at 11:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Mon, 2021-11-29 at 08:26 -0800, Mark Dilger wrote:\\n>\\n> > > I agree that if we want to do all of this then that would require a\\n> > > lot of changes. However, giving an error for RLS-enabled tables\\n> > > might\\n> > > also be too restrictive. The few alternatives could be that (a) we\\n> > > allow subscription owners to be either have \\\"bypassrls\\\" attribute\\n> > > or\\n> > > they could be superusers. (b) don't allow initial table_sync for\\n> > > rls\\n> > > enabled tables. (c) evaluate/analyze what is required to allow Copy\\n> > > From to start respecting RLS policies. (d) reject replicating any\\n> > > changes to tables that have RLS enabled.\\n>\\n> Maybe a combination?\\n>\\n> Allow subscriptions with copy_data=true iff the subscription owner is\\n> bypassrls or superuser. And then enforce RLS+WCO during\\n> insert/update/delete.\\n>\\n\\nYeah, that sounds reasonable to me.\\n\\n> I don't think it's a big change (correct me if I'm wrong),\\n>\\n\\nYeah, I also don't think it should be a big change.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 30 Nov 2021 17:19:13 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 30, 2021 at 12:56 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Mon, 2021-11-29 at 09:43 +0530, Amit Kapila wrote:\\n> > The first reason is that way it would be consistent with what we can\\n> > see while doing the operations from the backend.\\n>\\n> Logical replication is not interactive, so it doesn't seem quite the\\n> same.\\n>\\n> If you have a long running INSERT INTO SELECT or COPY FROM, the\\n> permission checks just happen at the beginning. As a user, it wouldn't\\n> surprise me if logical replication was similar.\\n>\\n> > operation. Another reason is to make behavior predictable as users\\n> > can\\n> > always expect when exactly the privilege change will be reflected and\\n> > it won't depend on the number of changes in the transaction.\\n>\\n> This patch does detect ownership changes more quickly (at the\\n> transaction boundary) than the current code (only when it reloads for\\n> some other reason). Transaction boundary seems like a reasonable time\\n> to detect the change to me.\\n>\\n> Detecting faster might be nice, but I don't have a strong opinion about\\n> it and I don't see why it necessarily needs to happen before this patch\\n> goes in.\\n>\\n\\nI think it would be better to do it before we allow subscription\\nowners to be non-superusers.\\n\\n> Also, do you think the cost of doing maybe_reread_subscription() per-\\n> tuple instead of per-transaction would be detectable?\\n>\\n\\nYeah, it is possible that is why I suggested in one of the emails\\nabove to allow changing the owners only for disabled subscriptions.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 30 Nov 2021 17:25:40 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\\n> I think it would be better to do it before we allow subscription\\n> owners to be non-superusers.\\n\\nThere are a couple other things to consider before allowing non-\\nsuperusers to create subscriptions anyway. For instance, a non-\\nsuperuser shouldn't be able to use a connection string that reads the\\ncertificate file from the server unless they also have\\npg_read_server_files privs.\\n\\n> Yeah, it is possible that is why I suggested in one of the emails\\n> above to allow changing the owners only for disabled subscriptions.\\n\\nThe current patch detects the following cases at the transaction\\nboundary:\\n\\n * ALTER SUBSCRIPTION ... OWNER TO ...\\n * ALTER ROLE ... NOSUPERUSER\\n * privileges revoked one way or another (aside from the RLS/WCO\\nproblems, which will be fixed)\\n\\nIf we want to detect at row boundaries we need to capture all of those\\ncases too, or else we're being inconsistent. The latter two cannot be\\ntied to whether the subscription is disabled or not, so I don't think\\nthat's a complete solution.\\n\\nHow about (as a separate patch) we just do maybe_reread_subscription()\\nevery K operations within a transaction? That would speed up\\npermissions errors if a revoke happens.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 30 Nov 2021 12:42:13 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\\n> > I think it would be better to do it before we allow subscription\\n> > owners to be non-superusers.\\n>\\n> There are a couple other things to consider before allowing non-\\n> superusers to create subscriptions anyway. For instance, a non-\\n> superuser shouldn't be able to use a connection string that reads the\\n> certificate file from the server unless they also have\\n> pg_read_server_files privs.\\n>\\n\\nIsn't allowing to create subscriptions via non-superusers and allowing\\nto change the owner two different things? I am under the impression\\nthat the latter one is more towards allowing the workers to apply\\nchanges with a non-superuser role.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Dec 2021 19:06:17 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 1, 2021, at 5:36 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>> \\n>> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\\n>>> I think it would be better to do it before we allow subscription\\n>>> owners to be non-superusers.\\n>> \\n>> There are a couple other things to consider before allowing non-\\n>> superusers to create subscriptions anyway. For instance, a non-\\n>> superuser shouldn't be able to use a connection string that reads the\\n>> certificate file from the server unless they also have\\n>> pg_read_server_files privs.\\n>> \\n> \\n> Isn't allowing to create subscriptions via non-superusers and allowing\\n> to change the owner two different things? I am under the impression\\n> that the latter one is more towards allowing the workers to apply\\n> changes with a non-superuser role.\\n\\nThe short-term goal is to have logical replication workers respect the privileges of the role which owns the subscription.\\n\\nThe long-term work probably includes creating a predefined role with permission to create subscriptions, and the ability to transfer those subscriptions to roles who might be neither superuser nor members of any particular predefined role; the idea being that logical replication subscriptions can be established without any superuser involvement, and may thereafter run without any special privilege.\\n\\nThe more recent patches on this thread are not as ambitious as the earlier patch-sets. We are no longer trying to support transferring subscriptions to non-superusers.\\n\\nRight now, on HEAD, if a subscription owner has superuser revoked, the subscription can continue to operate as superuser in so far as its replication actions are concerned. That seems like a pretty big security hole.\\n\\nThis patch mostly plugs that hole by adding permissions checks, so that a subscription owned by a role who has privileges revoked cannot (for the most part) continue to act under the old privileges.\\n\\nThere are two problematic edge cases that can occur after transfer of ownership. Remember, the new owner is required to be superuser for the transfer of ownership to occur.\\n\\n1) A subscription is transferred to a new owner, and the new owner then has privilege revoked.\\n\\n2) A subscription is transferred to a new owner, and then the old owner has privileges increased.\\n\\nIn both cases, a currently running logical replication worker may finish a transaction in progress acting with the current privileges of the old owner. The clearest solution is, as you suggest, to refuse transfer of ownership of subscriptions that are enabled.\\n\\nDoing so will create a failure case for REASSIGN OWNED BY. Will that be ok?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Dec 2021 11:21:35 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 2, 2021 at 12:51 AM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n>\\n> > On Dec 1, 2021, at 5:36 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >\\n> > On Wed, Dec 1, 2021 at 2:12 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> >>\\n> >> On Tue, 2021-11-30 at 17:25 +0530, Amit Kapila wrote:\\n> >>> I think it would be better to do it before we allow subscription\\n> >>> owners to be non-superusers.\\n> >>\\n> >> There are a couple other things to consider before allowing non-\\n> >> superusers to create subscriptions anyway. For instance, a non-\\n> >> superuser shouldn't be able to use a connection string that reads the\\n> >> certificate file from the server unless they also have\\n> >> pg_read_server_files privs.\\n> >>\\n> >\\n> > Isn't allowing to create subscriptions via non-superusers and allowing\\n> > to change the owner two different things? I am under the impression\\n> > that the latter one is more towards allowing the workers to apply\\n> > changes with a non-superuser role.\\n>\\n> The short-term goal is to have logical replication workers respect the privileges of the role which owns the subscription.\\n>\\n> The long-term work probably includes creating a predefined role with permission to create subscriptions, and the ability to transfer those subscriptions to roles who might be neither superuser nor members of any particular predefined role; the idea being that logical replication subscriptions can be established without any superuser involvement, and may thereafter run without any special privilege.\\n>\\n> The more recent patches on this thread are not as ambitious as the earlier patch-sets. We are no longer trying to support transferring subscriptions to non-superusers.\\n>\\n> Right now, on HEAD, if a subscription owner has superuser revoked, the subscription can continue to operate as superuser in so far as its replication actions are concerned. That seems like a pretty big security hole.\\n>\\n> This patch mostly plugs that hole by adding permissions checks, so that a subscription owned by a role who has privileges revoked cannot (for the most part) continue to act under the old privileges.\\n>\\n\\nIf we want to maintain the property that subscriptions can only be\\nowned by superuser for your first version then isn't a simple check\\nlike ((!superuser()) for each of the operations is sufficient?\\n\\n> There are two problematic edge cases that can occur after transfer of ownership. Remember, the new owner is required to be superuser for the transfer of ownership to occur.\\n>\\n> 1) A subscription is transferred to a new owner, and the new owner then has privilege revoked.\\n>\\n> 2) A subscription is transferred to a new owner, and then the old owner has privileges increased.\\n>\\n\\nIn (2), I am not clear what do you mean by \\\"the old owner has\\nprivileges increased\\\"? If the owners can only be superusers then what\\ndoes it mean to increase the privileges.\\n\\n> In both cases, a currently running logical replication worker may finish a transaction in progress acting with the current privileges of the old owner. The clearest solution is, as you suggest, to refuse transfer of ownership of subscriptions that are enabled.\\n>\\n> Doing so will create a failure case for REASSIGN OWNED BY. Will that be ok?\\n>\\n\\nI think so. Do we see any problem with that? I think we have some\\nfailure cases currently as well like \\\"All Tables Publication\\\" can only\\nbe owned by superusers whereas ownership for others can be to\\nnon-superusers and similarly we can't change ownership for pinned\\nobjects. I think the case being discussed is not exactly the same but\\nI am not able to see a problem with it.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Dec 2021 14:59:46 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 2, 2021, at 1:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> If we want to maintain the property that subscriptions can only be\\n> owned by superuser for your first version then isn't a simple check\\n> like ((!superuser()) for each of the operations is sufficient?\\n\\nAs things stand today, nothing prevents a superuser subscription owner from having superuser revoked. The patch does nothing to change this.\\n\\n> In (2), I am not clear what do you mean by \\\"the old owner has\\n> privileges increased\\\"? If the owners can only be superusers then what\\n> does it mean to increase the privileges.\\n\\nThe old owner may have had privileges reduced (no superuser, only permission to write into a specific schema, etc.) and the subscription enabled only after those privilege reductions were put in place. This is a usage pattern this patch is intended to support, by honoring those privilege restrictions.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Dec 2021 05:31:46 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 3, 2021 at 10:37 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Dec 2, 2021, at 1:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >\\n> > If we want to maintain the property that subscriptions can only be\\n> > owned by superuser for your first version then isn't a simple check\\n> > like ((!superuser()) for each of the operations is sufficient?\\n>\\n> As things stand today, nothing prevents a superuser subscription owner from having superuser revoked. The patch does nothing to change this.\\n>\\n\\nI understand that but won't that get verified when we look up the\\ninformation in pg_authid as part of superuser() check?\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Dec 2021 15:49:52 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n>>> If we want to maintain the property that subscriptions can only be\\n>>> owned by superuser\\n\\nWe don't want to maintain such a property, or at least, that's not what I want. I don't think that's what Jeff wants, either.\\n\\nTo clarify, I'm not entirely sure how to interpret the verb \\\"maintain\\\" in your question, since before the patch the property does not exist, and after the patch, it continues to not exist. We could *add* such a property, of course, though this patch does not attempt any such thing.\\n\\n> I understand that but won't that get verified when we look up the\\n> information in pg_authid as part of superuser() check?\\n\\nIf we added a superuser() check, then yes, but that would take things in a direction I do not want to go.\\n\\nAs I perceive the roadmap:\\n\\n1) Fix the current bug wherein subscription changes are applied with superuser force after the subscription owner has superuser privileges revoked.\\n2) Allow the transfer of subscriptions to non-superuser owners.\\n3) Allow the creation of subscriptions by non-superusers who are members of some as yet to be created predefined role, say \\\"pg_create_subscriptions\\\"\\n\\nI may be wrong, but it sounds like you interpret the intent of this patch as enforcing superuserness. That's not so. This patch intends to correctly handle the situation where a subscription is owned by a non-superuser (task 1, above) without going so far as creating new paths by which that situation could arise (tasks 2 and 3, above).\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Dec 2021 07:56:56 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Le lundi 6 décembre 2021, 16:56:56 CET Mark Dilger a écrit :\\n> > On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >>> If we want to maintain the property that subscriptions can only be\\n> >>> owned by superuser\\n> \\n> We don't want to maintain such a property, or at least, that's not what I\\n> want. I don't think that's what Jeff wants, either.\\n\\nThat's not what I want either: the ability to run and refresh subscriptions as \\na non superuser is a desirable feature. \\n\\nThe REFRESH part was possible before PG 14, when it was allowed to run REFRESH \\nin a function, which could be made to run as security definer. \\n\\n\\n> As I perceive the roadmap:\\n> \\n> 1) Fix the current bug wherein subscription changes are applied with\\n> superuser force after the subscription owner has superuser privileges\\n> revoked. 2) Allow the transfer of subscriptions to non-superuser owners.\\n> 3) Allow the creation of subscriptions by non-superusers who are members of\\n> some as yet to be created predefined role, say \\\"pg_create_subscriptions\\\"\\n\\nThis roadmap seems sensible.\\n\\n-- \\nRonan Dunklau\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 07 Dec 2021 10:39:43 +0100\",\n \"msg_from\": \"Ronan Dunklau <ronan.dunklau@aiven.io>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 6, 2021 at 9:26 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Dec 6, 2021, at 2:19 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >\\n> >>> If we want to maintain the property that subscriptions can only be\\n> >>> owned by superuser\\n>\\n> We don't want to maintain such a property, or at least, that's not what I want. I don't think that's what Jeff wants, either.\\n>\\n> To clarify, I'm not entirely sure how to interpret the verb \\\"maintain\\\" in your question, since before the patch the property does not exist, and after the patch, it continues to not exist. We could *add* such a property, of course, though this patch does not attempt any such thing.\\n>\\n\\nOkay, let me try to explain again. Following is the text from docs\\n[1]: \\\" (a) To create a subscription, the user must be a superuser. (b)\\nThe subscription apply process will run in the local database with the\\nprivileges of a superuser. (c) Privileges are only checked once at the\\nstart of a replication connection. They are not re-checked as each\\nchange record is read from the publisher, nor are they re-checked for\\neach change when applied.\\n\\nMy understanding is that we want to improve what is written as (c)\\nwhich I think is the same as what you mentioned later as \\\"Fix the\\ncurrent bug wherein subscription changes are applied with superuser\\nforce after the subscription owner has superuser privileges revoked.\\\".\\nAm I correct till here? If so, I think what I am suggesting should fix\\nthis with the assumption that we still want to follow (b) at least for\\nthe first patch. One possibility is that our understanding of the\\nfirst problem is the same but you want to allow apply worker running\\neven when superuser privileges are revoked provided the user with\\nwhich it is running has appropriate privileges on the objects being\\naccessed by apply worker.\\n\\nWe will talk about other points of the roadmap you mentioned once our\\nunderstanding for the first one matches.\\n\\n[1] - https://www.postgresql.org/docs/devel/logical-replication-security.html\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 15:59:17 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 7, 2021, at 2:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> \\n> Okay, let me try to explain again. Following is the text from docs\\n> [1]: \\\" (a) To create a subscription, the user must be a superuser. (b)\\n> The subscription apply process will run in the local database with the\\n> privileges of a superuser. (c) Privileges are only checked once at the\\n> start of a replication connection. They are not re-checked as each\\n> change record is read from the publisher, nor are they re-checked for\\n> each change when applied.\\n> \\n> My understanding is that we want to improve what is written as (c)\\n> which I think is the same as what you mentioned later as \\\"Fix the\\n> current bug wherein subscription changes are applied with superuser\\n> force after the subscription owner has superuser privileges revoked.\\\".\\n> Am I correct till here? If so, I think what I am suggesting should fix\\n> this with the assumption that we still want to follow (b) at least for\\n> the first patch.\\n\\nOk, that's a point of disagreement. I was trying to fix both (b) and (c) in the first patch.\\n\\n> One possibility is that our understanding of the\\n> first problem is the same but you want to allow apply worker running\\n> even when superuser privileges are revoked provided the user with\\n> which it is running has appropriate privileges on the objects being\\n> accessed by apply worker.\\n\\nCorrect, that's what I'm trying to make safe.\\n\\n> We will talk about other points of the roadmap you mentioned once our\\n> understanding for the first one matches.\\n\\nI am happy to have an off-list phone call with you, if you like.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 06:55:51 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 7, 2021 at 8:25 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Dec 7, 2021, at 2:29 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >\\n> > Okay, let me try to explain again. Following is the text from docs\\n> > [1]: \\\" (a) To create a subscription, the user must be a superuser. (b)\\n> > The subscription apply process will run in the local database with the\\n> > privileges of a superuser. (c) Privileges are only checked once at the\\n> > start of a replication connection. They are not re-checked as each\\n> > change record is read from the publisher, nor are they re-checked for\\n> > each change when applied.\\n> >\\n> > My understanding is that we want to improve what is written as (c)\\n> > which I think is the same as what you mentioned later as \\\"Fix the\\n> > current bug wherein subscription changes are applied with superuser\\n> > force after the subscription owner has superuser privileges revoked.\\\".\\n> > Am I correct till here? If so, I think what I am suggesting should fix\\n> > this with the assumption that we still want to follow (b) at least for\\n> > the first patch.\\n>\\n> Ok, that's a point of disagreement. I was trying to fix both (b) and (c) in the first patch.\\n>\\n\\nBut, I think as soon as we are trying to fix (b), we seem to be\\nallowing non-superusers to apply changes. If we want to do that then\\nwe should be even allowed to change the owners to non-superusers. I\\nwas thinking of the below order:\\n1. First fix (c) from the above description \\\"Privileges are only\\nchecked once at the start of a replication connection.\\\"\\n2A. Allow the transfer of subscriptions to non-superuser owners. This\\nwill be allowed only on disabled subscriptions to make this action\\npredictable.\\n2B. The apply worker should be able to apply the changes provided the\\nuser has appropriate privileges on the objects being accessed by apply\\nworker.\\n3) Allow the creation of subscriptions by non-superusers who are\\nmembers of some as yet to be created predefined role, say\\n\\\"pg_create_subscriptions\\\"\\n\\nWe all seem to agree that (3) can be done later as an independent\\nproject. 2A, 2B can be developed as separate patches but they need to\\nbe considered together for commit. After 2A, 2B, the first one (1)\\nwon't be required so, in fact, we can just ignore (1) but the only\\nbenefit I see is that if we stuck with some design problem during the\\ndevelopment of 2A, 2B, we would have at least something better than\\nwhat we have now.\\n\\nYou seem to be indicating let's do 2B first as that will anyway be\\nused later after 2A and 1 won't be required if we do that. I see that\\nbut I personally feel either we should follow 1, 2(A, B) or just do\\n2(A, B).\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 10:28:24 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > This patch does detect ownership changes more quickly (at the\\n> > transaction boundary) than the current code (only when it reloads for\\n> > some other reason). Transaction boundary seems like a reasonable time\\n> > to detect the change to me.\\n> >\\n> > Detecting faster might be nice, but I don't have a strong opinion about\\n> > it and I don't see why it necessarily needs to happen before this patch\\n> > goes in.\\n>\\n> I think it would be better to do it before we allow subscription\\n> owners to be non-superusers.\\n\\nI think it would be better not to ever do it at any time.\\n\\nIt seems like a really bad idea to me to change the run-as user in the\\nmiddle of a transaction. That seems prone to producing all sorts of\\nconfusing behavior that's hard to understand, and hard to test. So\\nwhat are we to do if a change occurs mid-transaction? I think we can\\neither finish replicating the current transaction and then switch to\\nthe new owner for the next transaction, or we could abort the current\\nattempt to replicate the transaction and retry the whole transaction\\nwith the new run-as user. My guess is that most users would prefer the\\nformer behavior to the latter.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 10:41:21 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 8, 2021 at 11:58 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> But, I think as soon as we are trying to fix (b), we seem to be\\n> allowing non-superusers to apply changes. If we want to do that then\\n> we should be even allowed to change the owners to non-superusers. I\\n> was thinking of the below order:\\n> 1. First fix (c) from the above description \\\"Privileges are only\\n> checked once at the start of a replication connection.\\\"\\n> 2A. Allow the transfer of subscriptions to non-superuser owners. This\\n> will be allowed only on disabled subscriptions to make this action\\n> predictable.\\n> 2B. The apply worker should be able to apply the changes provided the\\n> user has appropriate privileges on the objects being accessed by apply\\n> worker.\\n> 3) Allow the creation of subscriptions by non-superusers who are\\n> members of some as yet to be created predefined role, say\\n> \\\"pg_create_subscriptions\\\"\\n>\\n> We all seem to agree that (3) can be done later as an independent\\n> project. 2A, 2B can be developed as separate patches but they need to\\n> be considered together for commit. After 2A, 2B, the first one (1)\\n> won't be required so, in fact, we can just ignore (1) but the only\\n> benefit I see is that if we stuck with some design problem during the\\n> development of 2A, 2B, we would have at least something better than\\n> what we have now.\\n>\\n> You seem to be indicating let's do 2B first as that will anyway be\\n> used later after 2A and 1 won't be required if we do that. I see that\\n> but I personally feel either we should follow 1, 2(A, B) or just do\\n> 2(A, B).\\n\\n1 and 2B seem to require changing the same code, or related code. 1A\\nseems to require a completely different set of changes. If I'm right\\nabout that, it seems like a good reason for doing 1+2B first and\\nleaving 2A for a separate patch.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 10:47:03 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 9, 2021, at 7:41 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>>> This patch does detect ownership changes more quickly (at the\\n>>> transaction boundary) than the current code (only when it reloads for\\n>>> some other reason). Transaction boundary seems like a reasonable time\\n>>> to detect the change to me.\\n>>> \\n>>> Detecting faster might be nice, but I don't have a strong opinion about\\n>>> it and I don't see why it necessarily needs to happen before this patch\\n>>> goes in.\\n>> \\n>> I think it would be better to do it before we allow subscription\\n>> owners to be non-superusers.\\n> \\n> I think it would be better not to ever do it at any time.\\n> \\n> It seems like a really bad idea to me to change the run-as user in the\\n> middle of a transaction.\\n\\nI agree. We allow SET ROLE inside transactions, but faking one on the subscriber seems odd. No such role change was performed on the publisher side, nor is there a principled reason for assuming the old run-as role has membership in the new run-as role, so we'd be pretending to do something that might otherwise be impossible.\\n\\nThere was some discussion off-list about having the apply worker take out a lock on its subscription, thereby blocking ownership changes mid-transaction. I coded that and it seems to work fine, but I have a hard time seeing how the lock traffic would be worth expending. Between (a) changing roles mid-transaction, and (b) locking the subscription for each transaction, I'd prefer to do neither, but (b) seems far better than (a). Thoughts?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 09:22:07 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 9, 2021, at 7:47 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> 1 and 2B seem to require changing the same code, or related code. 1A\\n> seems to require a completely different set of changes. If I'm right\\n> about that, it seems like a good reason for doing 1+2B first and\\n> leaving 2A for a separate patch.\\n\\nThere are unresolved problems with 2A and 3 which were discussed upthread. I don't want to include fixes for them in this patch, as it greatly expands the scope of this patch, and is a logically separate effort. We can come back to those problems after this first patch is committed.\\n\\n\\nSpecifically, a non-superuser owner can perform ALTER SUBSCRIPTION and do things that are morally equivalent to creating a new subscription. This is problematic where things like the connection string are concerned, because it means the non-superuser owner can connect out to entirely different servers, without any access control checks to make sure the owner should be able to connect to these servers.\\n\\nThis problem already exists, right now. I'm not fixing it in this first patch, but I'm also not making it any worse.\\n\\nThe solution Jeff Davis proposed seems right to me. We change subscriptions to use a foreign server rather than a freeform connection string. When creating or altering a subscription, the role performing the action must have privileges on any foreign server they use.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 09:48:59 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 9, 2021 at 10:52 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Dec 9, 2021, at 7:41 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> >\\n> > On Tue, Nov 30, 2021 at 6:55 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >>> This patch does detect ownership changes more quickly (at the\\n> >>> transaction boundary) than the current code (only when it reloads for\\n> >>> some other reason). Transaction boundary seems like a reasonable time\\n> >>> to detect the change to me.\\n> >>>\\n> >>> Detecting faster might be nice, but I don't have a strong opinion about\\n> >>> it and I don't see why it necessarily needs to happen before this patch\\n> >>> goes in.\\n> >>\\n> >> I think it would be better to do it before we allow subscription\\n> >> owners to be non-superusers.\\n> >\\n> > I think it would be better not to ever do it at any time.\\n> >\\n> > It seems like a really bad idea to me to change the run-as user in the\\n> > middle of a transaction.\\n>\\n> I agree. We allow SET ROLE inside transactions, but faking one on the subscriber seems odd. No such role change was performed on the publisher side, nor is there a principled reason for assuming the old run-as role has membership in the new run-as role, so we'd be pretending to do something that might otherwise be impossible.\\n>\\n> There was some discussion off-list about having the apply worker take out a lock on its subscription, thereby blocking ownership changes mid-transaction. I coded that and it seems to work fine, but I have a hard time seeing how the lock traffic would be worth expending. Between (a) changing roles mid-transaction, and (b) locking the subscription for each transaction, I'd prefer to do neither, but (b) seems far better than (a). Thoughts?\\n>\\n\\nYeah, to me also (b) sounds better than (a). However, a few points\\nthat we might want to consider in that regard are as follows: 1.\\nlocking the subscription for each transaction will add new blocking\\nareas considering we acquire AccessExclusiveLock to change any\\nproperty of subscription. But as Alter Subscription won't be that\\nfrequent operation it might be acceptable. 2. It might lead to adding\\nsome cost to small transactions but not sure if that will be\\nnoticeable. 3. Tomorrow, if we want to make the apply-process parallel\\n(IIRC, we do have the patch for that somewhere in archives) especially\\nfor large in-progress transactions then this locking will have\\nadditional blocking w.r.t Altering Subscription. But again, this also\\nmight be acceptable.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 10 Dec 2021 09:45:08 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> Yeah, to me also (b) sounds better than (a). However, a few points\\n> that we might want to consider in that regard are as follows: 1.\\n> locking the subscription for each transaction will add new blocking\\n> areas considering we acquire AccessExclusiveLock to change any\\n> property of subscription. But as Alter Subscription won't be that\\n> frequent operation it might be acceptable.\\n\\nThe problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\\nIt's the cost of locking and unlocking the relation for every\\ntransaction we apply. Suppose it's a pgbench-type workload with a\\nsingle UPDATE per transaction. You've just limited the maximum\\npossible apply speed to about, I think, 30,000 transactions per second\\nno matter how many parallel workers you use, because that's how fast\\nthe lock manager is (or was, unless newer hardware or newer PG\\nversions have changed things in a way I don't know about). That seems\\nlike a poor idea. There's nothing wrong with noticing changes at the\\nnext transaction boundary, as long as we document it. So why would we\\nincur a possibly-significant performance cost to provide a stricter\\nguarantee?\\n\\nI bet users wouldn't even like this behavior. It would mean that if\\nyou are replicating a long-running transaction, an ALTER SUBSCRIPTION\\ncommand might block for a long time until replication of that\\ntransaction completes. I have a hard time understanding why anyone\\nwould consider that an improvement.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 10 Dec 2021 09:09:26 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 12/10/21 09:09, Robert Haas wrote:\\n> On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> Yeah, to me also (b) sounds better than (a). However, a few points\\n>> that we might want to consider in that regard are as follows: 1.\\n>> locking the subscription for each transaction will add new blocking\\n>> areas considering we acquire AccessExclusiveLock to change any\\n>> property of subscription. But as Alter Subscription won't be that\\n>> frequent operation it might be acceptable.\\n> The problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\\n> It's the cost of locking and unlocking the relation for every\\n> transaction we apply. Suppose it's a pgbench-type workload with a\\n> single UPDATE per transaction. You've just limited the maximum\\n> possible apply speed to about, I think, 30,000 transactions per second\\n> no matter how many parallel workers you use, because that's how fast\\n> the lock manager is (or was, unless newer hardware or newer PG\\n> versions have changed things in a way I don't know about). That seems\\n> like a poor idea. There's nothing wrong with noticing changes at the\\n> next transaction boundary, as long as we document it. So why would we\\n> incur a possibly-significant performance cost to provide a stricter\\n> guarantee?\\n>\\n> I bet users wouldn't even like this behavior. It would mean that if\\n> you are replicating a long-running transaction, an ALTER SUBSCRIPTION\\n> command might block for a long time until replication of that\\n> transaction completes. I have a hard time understanding why anyone\\n> would consider that an improvement.\\n>\\n\\n\\n+1\\n\\n\\nI think noticing changes at the transaction boundary is perfectly\\nacceptable.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 10 Dec 2021 10:20:02 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 10, 2021 at 7:39 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Thu, Dec 9, 2021 at 11:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > Yeah, to me also (b) sounds better than (a). However, a few points\\n> > that we might want to consider in that regard are as follows: 1.\\n> > locking the subscription for each transaction will add new blocking\\n> > areas considering we acquire AccessExclusiveLock to change any\\n> > property of subscription. But as Alter Subscription won't be that\\n> > frequent operation it might be acceptable.\\n>\\n> The problem isn't the cost of the locks taken by ALTER SUBSCRIPTION.\\n> It's the cost of locking and unlocking the relation for every\\n> transaction we apply.\\n>\\n\\nThis point is not clear to me as we are already locking the relation\\nwhile applying changes. I think here additional cost is to lock a\\nparticular subscription as well in addition to the relation on which\\nwe are going to perform apply. I agree that has a cost and that is why\\nI mentioned it as one of the points above and then also the\\nconcurrency effect as you also noted could make this idea moot.\\n\\n> Suppose it's a pgbench-type workload with a\\n> single UPDATE per transaction. You've just limited the maximum\\n> possible apply speed to about, I think, 30,000 transactions per second\\n> no matter how many parallel workers you use, because that's how fast\\n> the lock manager is (or was, unless newer hardware or newer PG\\n> versions have changed things in a way I don't know about). That seems\\n> like a poor idea. There's nothing wrong with noticing changes at the\\n> next transaction boundary, as long as we document it.\\n>\\n\\nIf we want to just document this then I think we should also keep in\\nmind that these could be N transactions as well if say tomorrow we\\nhave N parallel apply workers applying the N transactions in parallel.\\nI think it might also be possible that RLS policies won't be applied\\nfor initial table sync whereas those will be applied for later changes\\neven though the ownership has changed before both operations and one\\nof those happens to miss it. If that is possible, then it might be\\nbetter to avoid the same as it could appear inconsistent as mentioned\\nby Mark [1] as well. Now, it might be possible to avoid this by\\nimplementation or we can say that we don't care about this or just\\ndocument it. But it seems to me that if we have some way to detect the\\nchange of ownership at each operation level then no such possibilities\\nwould arise.\\n\\nThe other alternative we discussed was to allow a change of ownership\\non disabled subscriptions that way the apply behavior will always be\\npredictable.\\n\\nThere is clearly a merit in noticing the change of ownership at\\ntransaction boundary but just wanted to consider other possibilities.\\nIt could be that detecting at transaction-boundary is the best we can\\ndo but I think there is no harm in considering other possibilities.\\n\\n> So why would we\\n> incur a possibly-significant performance cost to provide a stricter\\n> guarantee?\\n>\\n> I bet users wouldn't even like this behavior. It would mean that if\\n> you are replicating a long-running transaction, an ALTER SUBSCRIPTION\\n> command might block for a long time until replication of that\\n> transaction completes.\\n>\\n\\nAgreed and if we decide to lock the subscription during the initial\\ntable sync phase then that could also take a long time for which again\\nusers might not be happy.\\n\\n[1] - https://www.postgresql.org/message-id/FE7D7024-6723-4ACB-82AB-94F6A194BE0D%40enterprisedb.com\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Sat, 11 Dec 2021 10:25:36 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"> On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> We need to do permission checking for WITH CHECK OPTION and RLS. The\\n> patch right now allows the subscription to write data that an RLS\\n> policy forbids.\\n\\nVersion 4 of the patch, attached, no longer allows RLS to be circumvented, but does so in a course-grained fashion. If the target table has row-level security policies which are enforced against the subscription owner, the replication draws an error, much as with a permissions failure. This seems sufficient for now, as superusers, roles with bypassrls, and target table owners should be able to replicate as before. We may want to revisit this later, perhaps if/when we address your ExecInsert question, below.\\n\\n> \\n> A couple other points:\\n> \\n> * We shouldn't refer to the behavior of previous versions in the docs\\n> unless there's a compelling reason\\n\\nFixed.\\n\\n> * Do we need to be smarter about partitioned tables, where an insert\\n> can turn into an update?\\n\\nIndeed, the logic of apply_handle_tuple_routing() required a bit of refactoring. Fixed in v4.\\n\\n> * Should we refactor to borrow logic from ExecInsert so that it's less\\n> likely that we miss something in the future?\\n\\nLet's just punt on this for now.\\n\\n\\n\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Wed, 15 Dec 2021 12:23:02 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 16, 2021 at 1:53 AM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n>\\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> >\\n> > We need to do permission checking for WITH CHECK OPTION and RLS. The\\n> > patch right now allows the subscription to write data that an RLS\\n> > policy forbids.\\n>\\n> Version 4 of the patch, attached.\\n>\\n\\nFor Update/Delete, we do read the table first via\\nFindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\\nbefore that?\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Sat, 8 Jan 2022 12:27:21 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\\n> For Update/Delete, we do read the table first via\\n> FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\\n> before that?\\n\\nIf it's logically an update/delete, then I think ACL_UPDATE/DELETE is\\nthe right one to check. Do you have a different opinion?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 07 Jan 2022 23:31:06 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-12-15 at 12:23 -0800, Mark Dilger wrote:\\n> > On Nov 24, 2021, at 4:30 PM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> > \\n> > We need to do permission checking for WITH CHECK OPTION and RLS.\\n> > The\\n> > patch right now allows the subscription to write data that an RLS\\n> > policy forbids.\\n> \\n> Version 4 of the patch, attached, no longer allows RLS to be\\n> circumvented, but does so in a course-grained fashion.\\n\\nCommitted.\\n\\nI tried to do some performance testing to see if there was any impact\\nof the extra catalog + ACL checks. Logical replication seems slow\\nenough -- something like 3X slower than local inserts -- that it didn't\\nseem to make a difference.\\n\\nTo test it, I did the following:\\n 1. sent a SIGSTOP to the logical apply worker\\n 2. loaded more data in publisher\\n 3. made the subscriber a sync replica\\n 4. timed the following:\\n a. sent a SIGCONT to the logical apply worker\\n b. insert a single tuple on the publisher side\\n c. wait for the insert to return, indicating that logical\\n replication is done up to that point\\n\\nDoes anyone have a better way to measure logical replication\\nperformance?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 07 Jan 2022 23:38:31 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Jan 8, 2022 at 1:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\\n> > For Update/Delete, we do read the table first via\\n> > FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\\n> > before that?\\n>\\n> If it's logically an update/delete, then I think ACL_UPDATE/DELETE is\\n> the right one to check. Do you have a different opinion?\\n>\\n\\nBut shouldn't we do it the first time before accessing the table?\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Sat, 8 Jan 2022 15:35:08 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, 2022-01-08 at 15:35 +0530, Amit Kapila wrote:\\n> On Sat, Jan 8, 2022 at 1:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > \\n> > On Sat, 2022-01-08 at 12:27 +0530, Amit Kapila wrote:\\n> > > For Update/Delete, we do read the table first via\\n> > > FindReplTupleInLocalRel(), so is there a need to check ACL_SELECT\\n> > > before that?\\n> > \\n> > If it's logically an update/delete, then I think ACL_UPDATE/DELETE\\n> > is\\n> > the right one to check. Do you have a different opinion?\\n> > \\n> \\n> But shouldn't we do it the first time before accessing the table?\\n\\nI'm not sure I follow the reasoning. Are you saying that, to logically\\nreplay a simple DELETE, the subscription owner should have SELECT\\nprivileges on the destination table?\\n\\nIs there a way that a subscription owner could somehow exploit a DELETE\\nprivilege to see the contents of a table on which they have no SELECT\\nprivileges? Or is it purely an internal read, which is necessary for\\nany ordinary local DELETE/UPDATE anyway?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sat, 08 Jan 2022 09:14:59 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Jeff Davis <pgsql@j-davis.com> writes:\\n> I'm not sure I follow the reasoning. Are you saying that, to logically\\n> replay a simple DELETE, the subscription owner should have SELECT\\n> privileges on the destination table?\\n\\nWe consider that DELETE WHERE <condition> requires SELECT privilege\\non the column(s) read by the <condition>. I suppose that the point\\nhere is to enforce the same privilege checks that occur in normal\\nSQL operation, so yes.\\n\\n> Is there a way that a subscription owner could somehow exploit a DELETE\\n> privilege to see the contents of a table on which they have no SELECT\\n> privileges?\\n\\nBEGIN;\\nDELETE FROM tab WHERE col = 'foo';\\n-- note deletion count\\nROLLBACK;\\n\\nNow you have some information about whether \\\"col\\\" contains 'foo'.\\nAdmittedly, it might be a pretty low-bandwidth way to extract data,\\nbut we still regard it as a privilege issue.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sat, 08 Jan 2022 12:37:49 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"... btw, I'd like to complain that this new test script consumes\\na completely excessive amount of time. On my fairly-new primary\\nworkstation:\\n\\n[12:48:00] t/027_nosuperuser.pl ............... ok 22146 ms ( 0.02 usr 0.00 sys + 1.12 cusr 0.95 csys = 2.09 CPU)\\n\\nThe previously-slowest script in the subscription suite is\\n\\n[12:48:23] t/100_bugs.pl ...................... ok 7048 ms ( 0.00 usr 0.00 sys + 2.85 cusr 0.99 csys = 3.84 CPU)\\n\\nand the majority of the scripts clock in at more like 2 to 4 seconds.\\nSo I don't think I'm out of line in saying that this test is consuming\\nan order of magnitude more time than is justified. I do not wish to\\nsee this much time added to every check-world run till kingdom come\\nfor this one feature/issue.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sat, 08 Jan 2022 12:57:18 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, 2022-01-08 at 12:57 -0500, Tom Lane wrote:\\n> ... btw, I'd like to complain that this new test script consumes\\n> a completely excessive amount of time.\\n\\nShould be fixed now; I brought the number of tests down from 100 to 14.\\nIt's not running in 2 seconds on my machine, but it's in line with the\\nother tests.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 09 Jan 2022 10:09:03 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Jeff Davis <pgsql@j-davis.com> writes:\\n> On Sat, 2022-01-08 at 12:57 -0500, Tom Lane wrote:\\n>> ... btw, I'd like to complain that this new test script consumes\\n>> a completely excessive amount of time.\\n\\n> Should be fixed now; I brought the number of tests down from 100 to 14.\\n> It's not running in 2 seconds on my machine, but it's in line with the\\n> other tests.\\n\\nThanks, I appreciate that.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 09 Jan 2022 14:10:22 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Jan 8, 2022 at 2:38 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> Committed.\\n\\nI was just noticing that what was committed here didn't actually fix\\nthe problem implied by the subject line. That is, non-superuser still\\ncan't own subscriptions. To put that another way, there's no way for\\nthe superuser to delegate the setup and administration of logical\\nreplication to a non-superuser. That's a bummer.\\n\\nReading the thread, I'm not quite sure why we seemingly did all the\\npreparatory work and then didn't actually fix the problem. It was\\npreviously proposed that we introduce a new predefined role\\npg_create_subscriptions and allow users who have the privileges of\\nthat predefined role to create and alter subscriptions. There are a\\nfew issues with that which, however, seem fairly solvable to me:\\n\\n1. Jeff pointed out that if you supply a connection string that is\\ngoing to try to access local files, you'd better have\\npg_read_server_files, or else we should not let you use that\\nconnection string. I guess that's mostly a function of which\\nparameters you specify, e.g. passfile, sslcert, sslkey, though maybe\\nfor host it depends on whether the value starts with a slash. We might\\nneed to think a bit here to make sure we get the rules right but it\\nseems like a pretty solvable problem.\\n\\n2. There was also quite a bit of discussion of what to do if a user\\nwho was previously eligible to own a subscription ceases to be\\neligible, in particular around a superuser who is made into a\\nnon-superuser, but the same problem would apply if you had\\npg_create_subscriptions or pg_read_server_files and then lost it. My\\nvote is to not worry about it too much. Specifically, I think we\\nshould certainly check whether the user has permission to create a\\nsubscription before letting them do so, but we could handle the case\\nwhere the user already owns a subscription and tries to modify it by\\neither allowing or denying the operation and I think either of those\\nwould be fine. I even think we could do one of those in some cases and\\nthe other in other cases and as long as there is some principle to the\\nthing, it's fine. I argue that it's not a normal configuration and\\ntherefore it doesn't have to work in a particularly useful way. It\\nshouldn't break the world in some horrendous way, but that's about as\\ngood as it needs to be. I'd argue for example that DROP SUBSCRIPTION\\ncould just check whether you own the object, and that ALTER\\nSUBSCRIPTION could check whether you own the object and, if you're\\nchanging the connection string, also whether you would have privileges\\nto set that new connection string on a new subscription.\\n\\n3. There was a bit of discussion of maybe wanting to allow users to\\ncreate subscriptions with some connection strings but not others,\\nperhaps by having some kind of intermediate object that owns the\\nconnection string and is owned by a superuser or someone with lots of\\nprivileges, and then letting a less-privileged user point a\\nsubscription at that object. I agree that might be useful to somebody,\\nbut I don't see why it's a hard requirement to get anything at all\\ndone here. Right now, a subscription contains a connection string\\ndirectly. If in the future someone wants to introduce a CREATE\\nREPLICATION DESTINATION command (or whatever) and have a way to point\\na subscription at a replication destination rather than a connection\\nstring directly, cool. Or if someone wants to wire this into CREATE\\nSERVER somehow, also cool. But if you don't care about restricting\\nwhich IPs somebody can try to access by providing a connection string\\nof their choice, then you would be happy if we just did something\\nsimple here and left this problem for another day.\\n\\nI am very curious to know (a) why work on this was abandoned (perhaps\\nthe answer is just lack of round tuits, in which case there is no more\\nto be said), and (b) what people think of (1)-(3) above, and (c)\\nwhether anyone knows of further problems that need to be considered\\nhere.\\n\\nThanks,\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 18 Jan 2023 14:38:21 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 18, 2023, at 11:38 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> I was just noticing that what was committed here didn't actually fix\\n> the problem implied by the subject line. That is, non-superuser still\\n> can't own subscriptions.\\n\\nNot so. They can. See src/test/subscription/027_nosuperuser.pl\\n\\n> To put that another way, there's no way for\\n> the superuser to delegate the setup and administration of logical\\n> replication to a non-superuser.\\n\\nTrue.\\n\\n> That's a bummer.\\n\\nAlso true.\\n\\n> Reading the thread, I'm not quite sure why we seemingly did all the\\n> preparatory work and then didn't actually fix the problem.\\n\\nPrior to the patch, if a superuser created a subscription, then later was demoted to non-superuser, the subscription apply workers still applied the changes with superuser force. So creating a superuser Alice, letting Alice create a subscription, then revoking superuser from Alice didn't accomplish anything interesting. But after the patch, it does. The superuser can now create non-superuser subscriptions. (I'm not sure this ability is well advertised.) But the problem of non-superuser roles creating non-superuser subscriptions is not solved.\\n\\nFrom a security perspective, the bit that was solved may be the more important part; from a usability perspective, perhaps not.\\n\\n> It was\\n> previously proposed that we introduce a new predefined role\\n> pg_create_subscriptions and allow users who have the privileges of\\n> that predefined role to create and alter subscriptions. There are a\\n> few issues with that which, however, seem fairly solvable to me:\\n> \\n> 1. Jeff pointed out that if you supply a connection string that is\\n> going to try to access local files, you'd better have\\n> pg_read_server_files, or else we should not let you use that\\n> connection string. I guess that's mostly a function of which\\n> parameters you specify, e.g. passfile, sslcert, sslkey, though maybe\\n> for host it depends on whether the value starts with a slash. We might\\n> need to think a bit here to make sure we get the rules right but it\\n> seems like a pretty solvable problem.\\n> \\n> 2. There was also quite a bit of discussion of what to do if a user\\n> who was previously eligible to own a subscription ceases to be\\n> eligible, in particular around a superuser who is made into a\\n> non-superuser, but the same problem would apply if you had\\n> pg_create_subscriptions or pg_read_server_files and then lost it. My\\n> vote is to not worry about it too much. Specifically, I think we\\n> should certainly check whether the user has permission to create a\\n> subscription before letting them do so, but we could handle the case\\n> where the user already owns a subscription and tries to modify it by\\n> either allowing or denying the operation and I think either of those\\n> would be fine. I even think we could do one of those in some cases and\\n> the other in other cases and as long as there is some principle to the\\n> thing, it's fine. I argue that it's not a normal configuration and\\n> therefore it doesn't have to work in a particularly useful way. It\\n> shouldn't break the world in some horrendous way, but that's about as\\n> good as it needs to be. I'd argue for example that DROP SUBSCRIPTION\\n> could just check whether you own the object, and that ALTER\\n> SUBSCRIPTION could check whether you own the object and, if you're\\n> changing the connection string, also whether you would have privileges\\n> to set that new connection string on a new subscription.\\n> \\n> 3. There was a bit of discussion of maybe wanting to allow users to\\n> create subscriptions with some connection strings but not others,\\n> perhaps by having some kind of intermediate object that owns the\\n> connection string and is owned by a superuser or someone with lots of\\n> privileges, and then letting a less-privileged user point a\\n> subscription at that object. I agree that might be useful to somebody,\\n> but I don't see why it's a hard requirement to get anything at all\\n> done here. Right now, a subscription contains a connection string\\n> directly. If in the future someone wants to introduce a CREATE\\n> REPLICATION DESTINATION command (or whatever) and have a way to point\\n> a subscription at a replication destination rather than a connection\\n> string directly, cool. Or if someone wants to wire this into CREATE\\n> SERVER somehow, also cool. But if you don't care about restricting\\n> which IPs somebody can try to access by providing a connection string\\n> of their choice, then you would be happy if we just did something\\n> simple here and left this problem for another day.\\n> \\n> I am very curious to know (a) why work on this was abandoned (perhaps\\n> the answer is just lack of round tuits, in which case there is no more\\n> to be said)\\n\\nMostly, it was a lack of round-tuits. After the patch was committed, I quickly switched my focus elsewhere.\\n\\n> , and (b) what people think of (1)-(3) above\\n\\nThere are different ways of solving (1), and Jeff and I discussed them in Dec 2021. My recollection was that idea (3) was the cleanest. Other ideas might be simpler than (3), or they may just appear simpler but in truth turn into a can of worms. I don't know, since I never went as far as trying to implement either approach.\\n\\nIdea (2) seems to contemplate non-superuser subscription owners as a theoretical thing, but it's quite real already. Again, see 027_nosuperuser.pl.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 18 Jan 2023 12:26:43 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 18, 2023 at 3:26 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> Prior to the patch, if a superuser created a subscription, then later was demoted to non-superuser, the subscription apply workers still applied the changes with superuser force. So creating a superuser Alice, letting Alice create a subscription, then revoking superuser from Alice didn't accomplish anything interesting. But after the patch, it does. The superuser can now create non-superuser subscriptions. (I'm not sure this ability is well advertised.) But the problem of non-superuser roles creating non-superuser subscriptions is not solved.\\n\\nAh, OK, thanks for the clarification!\\n\\n> There are different ways of solving (1), and Jeff and I discussed them in Dec 2021. My recollection was that idea (3) was the cleanest. Other ideas might be simpler than (3), or they may just appear simpler but in truth turn into a can of worms. I don't know, since I never went as far as trying to implement either approach.\\n>\\n> Idea (2) seems to contemplate non-superuser subscription owners as a theoretical thing, but it's quite real already. Again, see 027_nosuperuser.pl.\\n\\nI think the solution to the problem of a connection string trying to\\naccess local files is to just look at the connection string, decide\\nwhether it does that, and if yes, require the owner to have\\npg_read_server_files as well as pg_create_subscription. (3) is about\\ncreating some more sophisticated and powerful solution to that\\nproblem, but that seems like a nice-to-have, not something essential,\\nand a lot more complicated to implement.\\n\\nI guess what I listed as (2) is not relevant since I didn't understand\\ncorrectly what the current state of things is.\\n\\nUnless I'm missing something, it seems like this could be a quite small patch.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 18 Jan 2023 15:51:08 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> Unless I'm missing something, it seems like this could be a quite small patch.\\n\\nI didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\\n \\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 18 Jan 2023 12:58:26 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 18, 2023 at 3:58 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> > On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> >\\n> > Unless I'm missing something, it seems like this could be a quite small patch.\\n>\\n> I didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\\n\\nI wouldn't be OK with writing our own connection string parser for\\nthis purpose, but using PQconninfoParse seems OK. We still have to\\nembed knowledge of which connection string parameters can trigger\\nlocal file access, but that doesn't seem like a massive problem to me.\\nIf we already had (or have) that logic someplace else, it would\\nprobably make sense to reuse it, but if we don't, writing new logic\\ndoesn't seem prohibitively scary. I'm not 100% confident of my ability\\nto get those rules right on the first try, but I feel like whatever\\nproblems are there are just bugs that can be fixed with a few lines of\\ncode changes. The basic idea that by looking at which connection\\nstring properties are set we can tell what kinds of things the\\nconnection string is going to do seems sound to me.\\n\\nIf there's some reason that it isn't, that would be good to discover\\nnow rather than later.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 10:45:35 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-01-18 at 14:38 -0500, Robert Haas wrote:\\n> I was just noticing that what was committed here didn't actually fix\\n> the problem implied by the subject line. That is, non-superuser still\\n> can't own subscriptions. To put that another way, there's no way for\\n> the superuser to delegate the setup and administration of logical\\n> replication to a non-superuser. That's a bummer.\\n\\nRight, though as Mark pointed out, it does accomplish something even if\\nit's a bit unsatisfying. We could certainly do better here.\\n\\n> 2. There was also quite a bit of discussion of what to do if a user\\n> who was previously eligible to own a subscription ceases to be\\n> eligible, in particular around a superuser who is made into a\\n> non-superuser, but the same problem would apply\\n\\nCorrect, that's not a new problem, but exists in only a few places now.\\nOur privilege system is focused on \\\"what action can the user take right\\nnow?\\\", and gets weirder when it comes to object ownership, which is a\\nmore permanent thing.\\n\\nExtending that system to a subscription object, which has its own\\ncapabilities including a long-lived process, is cause for some\\nhesitation. I agree it's not necessarily a blocker.\\n\\n> 3. There was a bit of discussion of maybe wanting to allow users to\\n> create subscriptions with some connection strings but not others,\\n\\nThis was an alternative to trying to sanitize connection strings,\\nbecause it's a bit difficult to reason about what might be \\\"safe\\\"\\nconnection strings for a non-superuser, because it's environment-\\ndependent. But if we do identify a reasonable set of sanitization\\nrules, we can proceed without 3.\\n\\n> I am very curious to know (a) why work on this was abandoned (perhaps\\n> the answer is just lack of round tuits, in which case there is no\\n> more\\n> to be said), and (b) what people think of (1)-(3) above, and (c)\\n> whether anyone knows of further problems that need to be considered\\n> here.\\n\\n(a) Mostly round-tuits. There are problems and questions; but there are\\nwith any work, and they could be solved. Or, if they don't turn out to\\nbe terribly serious, we could ignore them.\\n\\n(b) When I pick this up again I would be inclined towards the\\nfollowing: try to solve 4-5 (listed below) first, which are\\nindependently useful; then look at both 1 and 3 to see which one\\npresents an agreeable solution faster. I'll probably ignore 2 because I\\ncouldn't get agreement the last time around (I think Mark objected to\\nthe idea of denying a drop in privileges).\\n\\n(c) Let me add:\\n\\n4. There are still differences between the subscription worker applying\\na change and going through the ordinary INSERT paths, for instance with\\nRLS. Also solvable.\\n\\n5. Andres raised in another thread the idea of switching to the table\\nowner when applying changes (perhaps in a\\nSECURITY_RESTRICTED_OPERATION?): \\n\\nhttps://www.postgresql.org/message-id/20230112033355.u5tiyr2bmuoc4jf4@awork3.anarazel.de\\n\\nThat seems related, and I like the idea.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 10:32:45 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-01-19 at 10:45 -0500, Robert Haas wrote:\\n> I wouldn't be OK with writing our own connection string parser for\\n> this purpose, but using PQconninfoParse seems OK. We still have to\\n> embed knowledge of which connection string parameters can trigger\\n> local file access, but that doesn't seem like a massive problem to\\n> me.\\n\\nAnother idea (I discussed with Andres some time ago) was to have an\\noption to libpq to turn off file access entirely. That could be a new\\nAPI function or a new connection option.\\n\\nThat would be pretty valuable by itself. Though we might want to\\nsupport a way to pass SSL keys as values rather than file paths, so\\nthat we can still do SSL.\\n\\nSo perhaps the answer is that it will be a small patch to get non-\\nsuperuser subscription owners, but we need three or four preliminary\\npatches first.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 10:40:12 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 19, 2023 at 1:40 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Thu, 2023-01-19 at 10:45 -0500, Robert Haas wrote:\\n> > I wouldn't be OK with writing our own connection string parser for\\n> > this purpose, but using PQconninfoParse seems OK. We still have to\\n> > embed knowledge of which connection string parameters can trigger\\n> > local file access, but that doesn't seem like a massive problem to\\n> > me.\\n>\\n> Another idea (I discussed with Andres some time ago) was to have an\\n> option to libpq to turn off file access entirely. That could be a new\\n> API function or a new connection option.\\n>\\n> That would be pretty valuable by itself. Though we might want to\\n> support a way to pass SSL keys as values rather than file paths, so\\n> that we can still do SSL.\\n\\nMaybe all of that would be useful, but it doesn't seem that mandatory.\\n\\n> So perhaps the answer is that it will be a small patch to get non-\\n> superuser subscription owners, but we need three or four preliminary\\n> patches first.\\n\\nI guess I'm not quite seeing it. Why can't we write a small patch to\\nget this working right now, probably in a few hours, and deal with any\\nimprovements that people want at a later time?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 14:11:46 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-01-19 at 14:11 -0500, Robert Haas wrote:\\n> I guess I'm not quite seeing it. Why can't we write a small patch to\\n> get this working right now, probably in a few hours, and deal with\\n> any\\n> improvements that people want at a later time?\\n\\nTo me, it's worrisome when there are more than a few loose ends, and\\nhere it seems like there are more like five. No single issue is a\\nblocker, but I believe we'd end up with a better user-facing solution\\nif we solved a couple of these lower-level issues (and think a little\\nmore about the other ones) before we expose new functionality to the\\nuser.\\n\\nThe predefined role is probably the biggest user-facing part of the\\nchange. Does it mean that members can create any number of any kind of\\nsubscription? If so it may be hard to tighten down later, because we\\ndon't know what existing setups might break.\\n\\nPerhaps we can just permit a superuser to \\\"ALTER SUBSCRIPTION ... OWNER\\nTO <non-super>\\\", which makes it simpler to use while still leaving the\\nresponisbility with the superuser to get it right. Maybe we even block\\nthe user from altering their own subscription (would be weird but not\\nmuch weirder than what we have now)? I don't know if that solves the\\nproblem you're trying to solve, but it seems lower-risk.\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 17:16:20 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-19 10:45:35 -0500, Robert Haas wrote:\\n> On Wed, Jan 18, 2023 at 3:58 PM Mark Dilger\\n> <mark.dilger@enterprisedb.com> wrote:\\n> > > On Jan 18, 2023, at 12:51 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> > >\\n> > > Unless I'm missing something, it seems like this could be a quite small patch.\\n> >\\n> > I didn't like the idea of the create/alter subscription commands needing to parse the connection string and think about what it might do, because at some point in the future we might extend what things are allowed in that string, and we have to keep everything that contemplates that string in sync. I may have been overly hesitant to tackle that problem. Or maybe I just ran short of round tuits.\\n> \\n> I wouldn't be OK with writing our own connection string parser for\\n> this purpose, but using PQconninfoParse seems OK. We still have to\\n> embed knowledge of which connection string parameters can trigger\\n> local file access, but that doesn't seem like a massive problem to me.\\n\\n> If we already had (or have) that logic someplace else, it would\\n> probably make sense to reuse it\\n\\nWe hve. See at least postgres_fdw's check_conn_params(), dblink's\\ndblink_connstr_check() and dblink_security_check().\\n\\nAs part of the fix for https://postgr.es/m/20220925232237.p6uskba2dw6fnwj2%40awork3.anarazel.de\\nI am planning to introduce a bunch of server side helpers for dealing with\\nlibpq (for establishing a connection while accepting interrupts). We could try\\nto centralize knowledge for those checks there.\\n\\nThe approach of checking, after connection establishment (see\\ndblink_security_check()), that we did in fact use the specified password,\\nscares me somewhat. See also below.\\n\\n\\n> The basic idea that by looking at which connection string properties are set\\n> we can tell what kinds of things the connection string is going to do seems\\n> sound to me.\\n\\nI don't think you *can* check it purely based on existing connection string\\nproperties, unfortunately. Think of e.g. a pg_hba.conf line of \\\"local all user\\npeer\\\" (quite reasonable config) or \\\"host all all 127.0.0.1/32 trust\\\" (less so).\\n\\nHence the hack with dblink_security_check().\\n\\n\\nI think there might be a discussion somewhere about adding an option to force\\nlibpq to not use certain auth methods, e.g. plaintext password/md5. It's\\npossible this could be integrated.\\n\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 17:46:28 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-19 17:16:20 -0800, Jeff Davis wrote:\\n> The predefined role is probably the biggest user-facing part of the\\n> change. Does it mean that members can create any number of any kind of\\n> subscription?\\n\\nI don't think we need to support complicated restriction schemes around this\\nnow. I'm sure such needs exist, but I think there's more places where a simple\\n\\\"allowed/not allowed\\\" suffices.\\n\\nYou'd presumably just grant such a permission to \\\"pseudo superuser\\\"\\nusers. They can typically do a lot of bad things already, so I don't really\\nsee the common need to prevent them from creating many subscriptions.\\n\\n\\n> If so it may be hard to tighten down later, because we don't know what\\n> existing setups might break.\\n\\nPresumably the unlimited number of subs case would still exist as an option\\nlater - so I don't see the problem?\\n\\n\\n> Perhaps we can just permit a superuser to \\\"ALTER SUBSCRIPTION ... OWNER\\n> TO <non-super>\\\", which makes it simpler to use while still leaving the\\n> responisbility with the superuser to get it right. Maybe we even block\\n> the user from altering their own subscription (would be weird but not\\n> much weirder than what we have now)? I don't know if that solves the\\n> problem you're trying to solve, but it seems lower-risk.\\n\\nThat seems to not really get us very far. It's hard to use for users, and hard\\nto make secure for the hosted PG providers.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 19 Jan 2023 17:51:22 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-01-19 at 17:51 -0800, Andres Freund wrote:\\n> I don't think we need to support complicated restriction schemes\\n> around this\\n> now. I'm sure such needs exist, but I think there's more places where\\n> a simple\\n> \\\"allowed/not allowed\\\" suffices.\\n\\nIf we did follow a path like 3 (having some kind of other object\\nrepresent the connection string), then it would create two different\\nkinds of subscriptions that might be controlled different ways, and\\nthere might be some rough edges. Might also be fine, or we might never\\npursue 3.\\n\\nI feel like my words are being interpreted as though I don't want this\\nfeature. I do, and I'm happy Robert re-raised it. I'm just trying to\\nanswer his questions about why I set the work down, which is that I\\nfelt some groundwork should be done before proceeding to a documented\\nfeature, and I still feel that's the right thing.\\n\\nBut (a) that's not a very strong objection; and (b) my efforts are\\nbetter spent doing some of that groundwork than arguing about the order\\nin which the work should be done. So, time permitting, I may be able to\\nput out a patch or two for the next 'fest.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 20 Jan 2023 00:04:12 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 19, 2023 at 8:46 PM Andres Freund <andres@anarazel.de> wrote:\\n> > I wouldn't be OK with writing our own connection string parser for\\n> > this purpose, but using PQconninfoParse seems OK. We still have to\\n> > embed knowledge of which connection string parameters can trigger\\n> > local file access, but that doesn't seem like a massive problem to me.\\n>\\n> > If we already had (or have) that logic someplace else, it would\\n> > probably make sense to reuse it\\n>\\n> We hve. See at least postgres_fdw's check_conn_params(), dblink's\\n> dblink_connstr_check() and dblink_security_check().\\n\\nThat's not the same thing. It doesn't know anything about other\\nparameters that might try to consult a local file, like sslcert,\\nsslkey, sslrootcert, sslca, sslcrl, sslcrldir, and maybe service.\\nMaybe you want to argue we don't need that, but that's what the\\nearlier discussion was about.\\n\\n> As part of the fix for https://postgr.es/m/20220925232237.p6uskba2dw6fnwj2%40awork3.anarazel.de\\n> I am planning to introduce a bunch of server side helpers for dealing with\\n> libpq (for establishing a connection while accepting interrupts). We could try\\n> to centralize knowledge for those checks there.\\n\\nMaybe. We could also add something into libpq, as Jeff proposed, e.g.\\na new connection parameter\\nthe_other_connection_parameters_might_try_to_trojan_the_local_host=1\\nblocks all that stuff from doing anything.\\n\\n> The approach of checking, after connection establishment (see\\n> dblink_security_check()), that we did in fact use the specified password,\\n> scares me somewhat. See also below.\\n\\nYes, I find that extremely dubious. It blocks things that you might\\nwant to do for legitimate reasons, including things that might be more\\nsecure than using a password. And there's no guarantee that it\\naccomplishes the intended objective either. The stated motivation for\\nthat restriction was. I believe, that we don't want the outbound\\nconnection to rely on the privileges available from the context in\\nwhich PostgreSQL itself is running -- but for all we know the remote\\nside has an IP filter that only allows the PostgreSQL host and no\\nothers. Moreover, it relies on us knowing what the behavior of the\\nremote server is, even though we have no way of knowing that that\\nserver shares our security interests.\\n\\nWorse still, I have always felt that the security vulnerability that\\nled to these controls being installed is pretty much fabricated: it's\\nan imaginary problem. Today I went back and found the original CVE at\\nhttps://nvd.nist.gov/vuln/detail/CVE-2007-3278 and it seems that at\\nleast one other person agrees. The Red Hat vendor statement on that\\npage says: \\\"Red Hat does not consider this do be a security issue.\\ndblink is disabled in default configuration of PostgreSQL packages as\\nshipped with Red Hat Enterprise Linux versions 2.1, 3, 4 and 5, and it\\nis a configuration decision whether to grant local users arbitrary\\naccess.\\\" I think whoever wrote that has an excellent point. I'm unable\\nto discern any legitimate security purpose for this restriction. What\\nI think it mostly does is (a) inconvenience users or (b) force them to\\nrely on a less-secure authentication method than they would otherwise\\nhave chosen.\\n\\n> > The basic idea that by looking at which connection string properties are set\\n> > we can tell what kinds of things the connection string is going to do seems\\n> > sound to me.\\n>\\n> I don't think you *can* check it purely based on existing connection string\\n> properties, unfortunately. Think of e.g. a pg_hba.conf line of \\\"local all user\\n> peer\\\" (quite reasonable config) or \\\"host all all 127.0.0.1/32 trust\\\" (less so).\\n>\\n> Hence the hack with dblink_security_check().\\n>\\n> I think there might be a discussion somewhere about adding an option to force\\n> libpq to not use certain auth methods, e.g. plaintext password/md5. It's\\n> possible this could be integrated.\\n\\nI still think you're talking about a different problem here. I'm\\ntalking about the problem of knowing whether local files are going to\\nbe accessed by the connection string.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 20 Jan 2023 08:25:46 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 20, 2023 at 8:25 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> I still think you're talking about a different problem here. I'm\\n> talking about the problem of knowing whether local files are going to\\n> be accessed by the connection string.\\n\\nSo here's a dumb patch for this. At least in my mind, the connection\\nstring sanitization/validation is the major design problem here, and\\nI'm not at all sure that what I did in the attached patch is right.\\nBut let's talk about that. This approach is inspired by Jeff's\\ncomments about local file access upthread, but as Andres pointed out,\\nthat's a completely different set of things than we worry about in\\nother places. I'm not quite sure what the right model is here.\\n\\nThis patch incidentally allows ALTER SUBSCRIPTION .. SKIP for any\\nsubscription owner, removing the existing check that limits that\\noperation to superusers and replacing it with nothing. I can't really\\nsee why this needs to be any more restricted than that, and\\nregrettably neither the check in the existing code nor the commit that\\nadded it have any comments explaining the logic behind that check. If,\\nfor example, skipping a subscription could lead to a server crash,\\nthat would be a reason to restrict the feature to superusers (or\\nrevert it). If it's just a case of the operation being maybe not the\\nright thing to do, that's not a sufficient reason to restrict it to\\nsuperusers. This change is really independent of the rest of the patch\\nand, if we want to do this, I will separate it into its own patch. But\\nsince this is just for discussion, I didn't worry about that right\\nnow.\\n\\nAside from the above, I don't yet see a problem here that I would\\nconsider to be serious enough that we couldn't proceed. I'll try to\\navoid too much repetition of what's already been said on this topic,\\nbut I do want to add that I think that creating subscriptions is\\nproperly viewed as a *slightly* scary operation, not a *very* scary\\noperation. It lets you do two things that you couldn't otherwise. One\\nis get background processes running that take up process slots and\\nconsume resources -- but note that your ability to consume resources\\nwith however many normal database connections you can make is\\nvirtually unlimited. The other thing it lets you do is poke around the\\nnetwork, maybe figure out whether some ports are open or closed, and\\ntry to replicate data from any accessible servers you can find, which\\ncould include ports or servers that you can't access directly. I think\\nthat the superuser will be in a good position to evaluate whether that\\nis a risk in a certain environment or not, and I think many superusers\\nwill conclude that it isn't a big risk. I think that the main\\nmotivation for NOT handing out pg_create_subscription will turn out to\\nbe administrative rather than security-related i.e. they'll want to be\\nsomething that falls under their authority rather than someone else's.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Fri, 20 Jan 2023 11:08:54 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-20 08:25:46 -0500, Robert Haas wrote:\\n> Worse still, I have always felt that the security vulnerability that\\n> led to these controls being installed is pretty much fabricated: it's\\n> an imaginary problem. Today I went back and found the original CVE at\\n> https://nvd.nist.gov/vuln/detail/CVE-2007-3278 and it seems that at\\n> least one other person agrees. The Red Hat vendor statement on that\\n> page says: \\\"Red Hat does not consider this do be a security issue.\\n> dblink is disabled in default configuration of PostgreSQL packages as\\n> shipped with Red Hat Enterprise Linux versions 2.1, 3, 4 and 5, and it\\n> is a configuration decision whether to grant local users arbitrary\\n> access.\\\" I think whoever wrote that has an excellent point. I'm unable\\n> to discern any legitimate security purpose for this restriction. What\\n> I think it mostly does is (a) inconvenience users or (b) force them to\\n> rely on a less-secure authentication method than they would otherwise\\n> have chosen.\\n\\nFWIW, I've certainly seen situations where having the checks prevented easy\\npaths to privilege escalations. That's not to say that I like the checks, but\\nI also don't think we can get away without them (or a better replacement, of\\ncourse).\\n\\nThere are good reasons to have 'peer' authentication set up for the user\\nrunning postgres, so admin scripts can connect without issues. Which\\nunfortunately then also means that postgres_fdw etc can connect to the current\\ndatabase as superuser, without that check. Which imo clearly is an issue.\\n\\nWhy do you think this is a fabricated issue?\\n\\n\\nThe solution we have is quite bad, of course. Just because the user isn't a\\nsuperuser \\\"immediately\\\" doesn't mean it doesn't have the rights to become\\none somehow.\\n\\n\\n> > > The basic idea that by looking at which connection string properties are set\\n> > > we can tell what kinds of things the connection string is going to do seems\\n> > > sound to me.\\n> >\\n> > I don't think you *can* check it purely based on existing connection string\\n> > properties, unfortunately. Think of e.g. a pg_hba.conf line of \\\"local all user\\n> > peer\\\" (quite reasonable config) or \\\"host all all 127.0.0.1/32 trust\\\" (less so).\\n> >\\n> > Hence the hack with dblink_security_check().\\n> >\\n> > I think there might be a discussion somewhere about adding an option to force\\n> > libpq to not use certain auth methods, e.g. plaintext password/md5. It's\\n> > possible this could be integrated.\\n> \\n> I still think you're talking about a different problem here. I'm\\n> talking about the problem of knowing whether local files are going to\\n> be accessed by the connection string.\\n\\nWhy is this only about local files, rather than e.g. also using the local\\nuser?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Sat, 21 Jan 2023 14:01:34 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-20 11:08:54 -0500, Robert Haas wrote:\\n> /*\\n> - * Validate connection info string (just try to parse it)\\n> + * Validate connection info string, and determine whether it might cause\\n> + * local filesystem access to be attempted.\\n> + *\\n> + * If the connection string can't be parsed, this function will raise\\n> + * an error and will not return. If it can, it will return true if local\\n> + * filesystem access may be attempted and false otherwise.\\n> */\\n> -static void\\n> +static bool\\n> libpqrcv_check_conninfo(const char *conninfo)\\n> {\\n> \\tPQconninfoOption *opts = NULL;\\n> +\\tPQconninfoOption *opt;\\n> \\tchar\\t *err = NULL;\\n> +\\tbool\\t\\tresult = false;\\n> \\n> \\topts = PQconninfoParse(conninfo, &err);\\n> \\tif (opts == NULL)\\n> @@ -267,7 +274,40 @@ libpqrcv_check_conninfo(const char *conninfo)\\n> \\t\\t\\t\\t errmsg(\\\"invalid connection string syntax: %s\\\", errcopy)));\\n> \\t}\\n> \\n> +\\tfor (opt = opts; opt->keyword != NULL; ++opt)\\n> +\\t{\\n> +\\t\\t/* Ignore connection options that are not present. */\\n> +\\t\\tif (opt->val == NULL)\\n> +\\t\\t\\tcontinue;\\n> +\\n> +\\t\\t/* For all these parameters, the value is a local filename. */\\n> +\\t\\tif (strcmp(opt->keyword, \\\"passfile\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"sslcert\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"sslkey\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"sslrootcert\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"sslcrl\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"sslcrldir\\\") == 0 ||\\n> +\\t\\t\\tstrcmp(opt->keyword, \\\"service\\\") == 0)\\n> +\\t\\t{\\n> +\\t\\t\\tresult = true;\\n> +\\t\\t\\tbreak;\\n> +\\t\\t}\\n\\nDo we need to think about 'options' allowing anything bad? I don't\\nimmediately* see a problem, but ...\\n\\n\\n> +\\n> +\\t\\t/*\\n> +\\t\\t * For the host parameter, the value might be a local filename.\\n> +\\t\\t * It might also be a reference to the local host's abstract UNIX\\n> +\\t\\t * socket namespace, which we consider equivalent to a local pathname\\n> +\\t\\t * for security purporses.\\n> +\\t\\t */\\n> +\\t\\tif (strcmp(opt->keyword, \\\"host\\\") == 0 && is_unixsock_path(opt->val))\\n> +\\t\\t{\\n> +\\t\\t\\tresult = true;\\n> +\\t\\t\\tbreak;\\n> +\\t\\t}\\n> +\\t}\\n\\nHm, what about kerberos / gss / SSPI? Aren't those essentially also tied to\\nthe local filesystem / user?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Sat, 21 Jan 2023 14:10:57 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, 2023-01-21 at 14:01 -0800, Andres Freund wrote:\\n> There are good reasons to have 'peer' authentication set up for the\\n> user\\n> running postgres, so admin scripts can connect without issues. Which\\n> unfortunately then also means that postgres_fdw etc can connect to\\n> the current\\n> database as superuser, without that check. Which imo clearly is an\\n> issue.\\n\\nPerhaps we should have a way to directly turn on/off authentication\\nmethods in libpq through API functions and/or options?\\n\\nThis reminds me of the \\\"channel_binding=required\\\" option. We considered\\nsome similar alternatives for that feature.\\n\\n> Why is this only about local files, rather than e.g. also using the\\n> local\\n> user?\\n\\nIt's not, but we happen to already have pg_read_server_files, and it\\nmakes sense to use that at least for files referenced directly in the\\nconnection string. You're right that it's incomplete, and also that it\\ndoesn't make a lot of sense for files accessed indirectly.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 22 Jan 2023 09:05:27 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-22 09:05:27 -0800, Jeff Davis wrote:\\n> On Sat, 2023-01-21 at 14:01 -0800, Andres Freund wrote:\\n> > There are good reasons to have 'peer' authentication set up for the\\n> > user\\n> > running postgres, so admin scripts can connect without issues. Which\\n> > unfortunately then also means that postgres_fdw etc can connect to\\n> > the current\\n> > database as superuser, without that check. Which imo clearly is an\\n> > issue.\\n> \\n> Perhaps we should have a way to directly turn on/off authentication\\n> methods in libpq through API functions and/or options?\\n\\nYes. There's an in-progress patch adding, I think, pretty much what is\\nrequired here:\\nhttps://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\\n\\nrequire_auth=a,b,c\\n\\nI think an allowlist approach is the right thing for the subscription (and\\npostgres_fdw/dblink) use case, otherwise we'll add some auth method down the\\nline without updating what's disallowed in the subscription code.\\n\\n\\n> > Why is this only about local files, rather than e.g. also using the local\\n> > user?\\n> \\n> It's not, but we happen to already have pg_read_server_files, and it\\n> makes sense to use that at least for files referenced directly in the\\n> connection string. You're right that it's incomplete, and also that it\\n> doesn't make a lot of sense for files accessed indirectly.\\n\\nI just meant that we need to pay attention to user-based permissions as well.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Sun, 22 Jan 2023 17:52:55 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Jan 21, 2023 at 5:01 PM Andres Freund <andres@anarazel.de> wrote:\\n> There are good reasons to have 'peer' authentication set up for the user\\n> running postgres, so admin scripts can connect without issues. Which\\n> unfortunately then also means that postgres_fdw etc can connect to the current\\n> database as superuser, without that check. Which imo clearly is an issue.\\n>\\n> Why do you think this is a fabricated issue?\\n\\nWell, if I have a bunch of PostgreSQL machines on the network that all\\nallow each other to log in without requiring anything much in the way\\nof passwords or closely-guarded SSL certificates or anything, and then\\nI grant to the users on those machines the right to make connections\\nto the other machines using arbitrary connection strings, whose fault\\nis it when security is compromised? We seem to be taking the policy\\nthat it's PostgreSQL's fault if it doesn't block something bad from\\nhappening there, but it seems to me that if you gate incoming\\nPostgreSQL connections only by source IP address and then also give\\nunprivileged users the ability to choose their source IP address, you\\nshould expect to have a problem.\\n\\nI will admit that this is not an open-and-shut case, because a\\npasswordless login back to the bootstrap superuser account from the\\nlocal machine is a pretty common scenario and doesn't feel\\nintrinsically unreasonable to me, and I hadn't thought about that as a\\npotential attack vector.\\n\\nHowever, I still think there's a problem with putting all the\\nresponsibility on PostgreSQL. The problem, specifically, is that we're\\nspeculating wildly as to the user's intent. If we say, as we currently\\ndo, that we're only going to allow connections if they require a\\npassword, then we're making a judgement that the superuser couldn't\\nhave intended to allow the postgres_fdw to make a passwordless\\nconnection. On the other hand, if we say, as we also currently do,\\nthat the postgres_fdw user is free to set the sslcert parameter to\\nanything they like, then we're making a judgement that the superuser\\nis totally OK with that being set to any file on the local filesystem.\\nNeither of those conclusions seems sound to me. The superuser may, or\\nmay not, have intended to allow passwordless logins, and they may, or\\nmay not, have intended for any SSL certificates stored locally to be\\nusable by outbound connection attempts.\\n\\nAnd that's what I really dislike about the you-must-use-a-password\\nrule that we have right now. It embeds a policy decision about what\\nusers do or do not want to allow. We've uncritically copied that\\npolicy decision around to more and more places, and we've added\\nworkarounds in some places for the fact that, well, you know, it might\\nnot actually be what everybody wants (6136e94d), but it doesn't seem\\nlike we've ever really acknowledged that we *made* a policy decision.\\nAnd that means we haven't really had a debate about the merits of this\\n*particular* rule, which seems to me to be highly debatable. It looks\\nto me like there's both stuff you might not want to allow that this\\nrule does not block, and also stuff you might want to allow that this\\nrule does block, and also that different people can want different\\nthings yet this rule applies uniformly to everyone.\\n\\n> > I still think you're talking about a different problem here. I'm\\n> > talking about the problem of knowing whether local files are going to\\n> > be accessed by the connection string.\\n>\\n> Why is this only about local files, rather than e.g. also using the local\\n> user?\\n\\nBecause there's nothing you can do about the local-user case.\\n\\nIf I'm asked to attempt to connect to a PostgreSQL server, and I\\nchoose to do that, and the connection succeeds, all I know is that the\\nconnection actually succeeded. I do not know why the remote machine\\nchose to accept the connection. If I supplied a password or an SSL\\ncertificate or some such thing, then it seems likely that the remote\\nmachine accepted that connection because I supplied that particular\\npassword or SSL certificate, but it could also be because the remote\\nmachine accepts all connections from Robert, or all connections\\nwhatsoever, or all connections on Mondays. I just don't know. If I'm\\nworried that the person is asking me to make the connection is trying\\nto trick me into doing something that they can't do themselves, I\\ncould refuse to read a password from a local password store or an SSL\\ncertificate from a local certificate file or otherwise refuse to do\\nanything special to try to get their connection request accepted, and\\nthen if it does get accepted anyway, I know that they weren't relying\\non any of those resources that I refused to use. But, if I attempt a\\nplain vanilla, totally password-less connection and it works, I have\\nno way of knowing whether that happened because I'm Robert or for some\\nother reason.\\n\\nTo put that another way, if I'm making a connection on behalf of an\\nuntrusted party, I can choose not to supply an SSL certificate, or not\\nto supply a password. But I cannot choose to not be myself.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 11:34:32 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sun, Jan 22, 2023 at 8:52 PM Andres Freund <andres@anarazel.de> wrote:\\n> > Perhaps we should have a way to directly turn on/off authentication\\n> > methods in libpq through API functions and/or options?\\n>\\n> Yes. There's an in-progress patch adding, I think, pretty much what is\\n> required here:\\n> https://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\\n>\\n> require_auth=a,b,c\\n>\\n> I think an allowlist approach is the right thing for the subscription (and\\n> postgres_fdw/dblink) use case, otherwise we'll add some auth method down the\\n> line without updating what's disallowed in the subscription code.\\n\\nSo what would we do here, exactly? We could force a require_auth\\nparameter into the provided connection string, although I'm not quite\\nsure of the details there, but what value should we force? Is that\\ngoing to be something hard-coded, or something configurable? If\\nconfigurable, where does that configuration get stored?\\n\\nRegardless, this only allows connection strings to be restricted along\\none axis: authentication type. If you want to let people connect only\\nto a certain subnet or whatever, you're still out of luck.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 12:39:50 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Jan 21, 2023 at 5:11 PM Andres Freund <andres@anarazel.de> wrote:\\n> > + /* For all these parameters, the value is a local filename. */\\n> > + if (strcmp(opt->keyword, \\\"passfile\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"sslcert\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"sslkey\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"sslrootcert\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"sslcrl\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"sslcrldir\\\") == 0 ||\\n> > + strcmp(opt->keyword, \\\"service\\\") == 0)\\n> > + {\\n> > + result = true;\\n> > + break;\\n> > + }\\n>\\n> Do we need to think about 'options' allowing anything bad? I don't\\n> immediately* see a problem, but ...\\n\\nIf it is, it'd be a different kind of bad. What these parameters all\\nhave in common is that they allow you to read some local file and\\nmaybe benefit from that during the authentication process. options\\ndoesn't let you to do anything like that, and by definition kind of\\ncan't, because it's just a string to be sent to the remote server. As\\nI noted in my other responses, the local superuser could want to\\nimpose any arbitrary restriction the connection strings users can\\nchoose, and so it's just as plausible that they want to restrict\\noptions as anything else; but this test is about something more\\nspecific.\\n\\n> > + /*\\n> > + * For the host parameter, the value might be a local filename.\\n> > + * It might also be a reference to the local host's abstract UNIX\\n> > + * socket namespace, which we consider equivalent to a local pathname\\n> > + * for security purporses.\\n> > + */\\n> > + if (strcmp(opt->keyword, \\\"host\\\") == 0 && is_unixsock_path(opt->val))\\n> > + {\\n> > + result = true;\\n> > + break;\\n> > + }\\n> > + }\\n>\\n> Hm, what about kerberos / gss / SSPI? Aren't those essentially also tied to\\n> the local filesystem / user?\\n\\nUh, I don't know. It doesn't seem so directly true as in these cases,\\nbut what's your thought?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 13:21:31 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-23 11:34:32 -0500, Robert Haas wrote:\\n> I will admit that this is not an open-and-shut case, because a\\n> passwordless login back to the bootstrap superuser account from the\\n> local machine is a pretty common scenario and doesn't feel\\n> intrinsically unreasonable to me, and I hadn't thought about that as a\\n> potential attack vector.\\n\\nI think it's 90% of the problem... There's IMO no particularly good\\nalternative to a passwordless login for the bootstrap superuser, and it's the\\naccount you least want to expose...\\n\\n\\n> > > I still think you're talking about a different problem here. I'm\\n> > > talking about the problem of knowing whether local files are going to\\n> > > be accessed by the connection string.\\n> >\\n> > Why is this only about local files, rather than e.g. also using the local\\n> > user?\\n> \\n> Because there's nothing you can do about the local-user case.\\n> \\n> If I'm asked to attempt to connect to a PostgreSQL server, and I\\n> choose to do that, and the connection succeeds, all I know is that the\\n> connection actually succeeded.\\n\\nWell, there is PQconnectionUsedPassword()... Not that it's a great answer.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 10:26:39 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> I will admit that this is not an open-and-shut case, because a\\n> passwordless login back to the bootstrap superuser account from the\\n> local machine is a pretty common scenario and doesn't feel\\n> intrinsically unreasonable to me, and I hadn't thought about that as a\\n> potential attack vector.\\n\\nIt seems to me like that's _the_ primary attack vector. I think I\\nagree with you that the password requirement is an overly large\\nhammer, but I don't think it's right (or safe/helpful to DBAs reading\\nalong) to describe it as a manufactured concern.\\n\\n> If I'm asked to attempt to connect to a PostgreSQL server, and I\\n> choose to do that, and the connection succeeds, all I know is that the\\n> connection actually succeeded. I do not know why the remote machine\\n> chose to accept the connection. If I supplied a password or an SSL\\n> certificate or some such thing, then it seems likely that the remote\\n> machine accepted that connection because I supplied that particular\\n> password or SSL certificate, but it could also be because the remote\\n> machine accepts all connections from Robert, or all connections\\n> whatsoever, or all connections on Mondays. I just don't know.\\n\\nAs of SYSTEM_USER, I think this is no longer the case -- after\\nconnection establishment, you can ask the server who was authenticated\\nand why. (It doesn't explain why you were authorized to be that\\nparticular user, but that seems maybe less important wen you're trying\\nto disallow ambient authentication.)\\n\\nIf my require_auth patchset gets in, you'd be able to improve on this\\nby rejecting all ambient forms of authentication at the protocol level\\n(require_auth=password,md5,scram-sha-256). You could even go a step\\nfurther and disable ambient transport authentication\\n(sslcertmode=disable gssencmode=disable), which keeps a proxied\\nconnection from making use of a client cert or a Kerberos cache. But\\nfor postgres_fdw, at least, that carries a risk of disabling current\\nuse cases. Stephen and I had a discussion about one such case in the\\nKerberos delegation thread [1].\\n\\nIt doesn't help you if you want to differentiate one form of ambient\\nauth (trust/peer/etc.) from another, since they look the same to the\\nprotocol. But for e.g. postgres_fdw I'm not sure why you would want to\\ndifferentiate between those cases, because they all seem bad.\\n\\n> To put that another way, if I'm making a connection on behalf of an\\n> untrusted party, I can choose not to supply an SSL certificate, or not\\n> to supply a password. But I cannot choose to not be myself.\\n\\n(IMO, you're driving towards a separation of the proxy identity from\\nthe user identity. Other protocols do that too.)\\n\\n--Jacob\\n\\n[1] https://www.postgresql.org/message-id/flat/23337c51-7a48-d5a8-569d-ef3ce6fe235f%40timescale.com#38b4033256d9d95773963ce938cbe3ea\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 10:27:27 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-23 12:39:50 -0500, Robert Haas wrote:\\n> On Sun, Jan 22, 2023 at 8:52 PM Andres Freund <andres@anarazel.de> wrote:\\n> > > Perhaps we should have a way to directly turn on/off authentication\\n> > > methods in libpq through API functions and/or options?\\n> >\\n> > Yes. There's an in-progress patch adding, I think, pretty much what is\\n> > required here:\\n> > https://www.postgresql.org/message-id/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com\\n> >\\n> > require_auth=a,b,c\\n> >\\n> > I think an allowlist approach is the right thing for the subscription (and\\n> > postgres_fdw/dblink) use case, otherwise we'll add some auth method down the\\n> > line without updating what's disallowed in the subscription code.\\n> \\n> So what would we do here, exactly? We could force a require_auth\\n> parameter into the provided connection string, although I'm not quite\\n> sure of the details there\\n\\nIf we parse the connection string first, we can ensure that our values take\\nprecedence, that shouldn't be an issue, I think.\\n\\n\\n> , but what value should we force? Is that going to be something hard-coded,\\n> or something configurable? If configurable, where does that configuration\\n> get stored?\\n\\nI would probably start with something hardcoded, perhaps with an adjusted\\nvalue depending on things like pg_read_server_files.\\n\\nI'd say just allowing password (whichever submethod), ssl is a good start,\\nwith something like your existing code to prevent file access for ssl unless\\npg_read_server_files is granted.\\n\\n\\nI don't think kerberos, gss, peer, sspi would be safe.\\n\\n\\n> Regardless, this only allows connection strings to be restricted along\\n> one axis: authentication type. If you want to let people connect only\\n> to a certain subnet or whatever, you're still out of luck.\\n\\nTrue. But I think it'd get us a large percentage of the use cases.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 10:35:33 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 1:26 PM Andres Freund <andres@anarazel.de> wrote:\\n> > If I'm asked to attempt to connect to a PostgreSQL server, and I\\n> > choose to do that, and the connection succeeds, all I know is that the\\n> > connection actually succeeded.\\n>\\n> Well, there is PQconnectionUsedPassword()... Not that it's a great answer.\\n\\nSure, but that's making an inference about why the remote side did\\nwhat it did. It's not fantastic to have a security model that relies\\non connecting to a server chosen by the user and having it tell us\\ntruthfully whether or not it relied on the password. Granted, it won't\\nlie unless it's been hacked, and we're trying to protect it, not\\nourselves, so the only thing that happens if it does lie is that it\\ngets hacked a second time, so I guess there's no real vulnerability?\\nBut I feel like we'd be on far sounder footing if we our security\\npolicy were based on deciding what we are willing to do (are we\\nwilling to read that file? are we willing to attempt that\\nauthentication method?) and before we actually do it, rather than on\\ntrying to decide after-the-fact whether what we did is OK based on\\nwhat the remote side tells us about how things turned out.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 13:39:43 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-23 10:27:27 -0800, Jacob Champion wrote:\\n> On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > I will admit that this is not an open-and-shut case, because a\\n> > passwordless login back to the bootstrap superuser account from the\\n> > local machine is a pretty common scenario and doesn't feel\\n> > intrinsically unreasonable to me, and I hadn't thought about that as a\\n> > potential attack vector.\\n> \\n> It seems to me like that's _the_ primary attack vector. I think I\\n> agree with you that the password requirement is an overly large\\n> hammer, but I don't think it's right (or safe/helpful to DBAs reading\\n> along) to describe it as a manufactured concern.\\n\\n+1\\n\\n\\n> > If I'm asked to attempt to connect to a PostgreSQL server, and I\\n> > choose to do that, and the connection succeeds, all I know is that the\\n> > connection actually succeeded. I do not know why the remote machine\\n> > chose to accept the connection. If I supplied a password or an SSL\\n> > certificate or some such thing, then it seems likely that the remote\\n> > machine accepted that connection because I supplied that particular\\n> > password or SSL certificate, but it could also be because the remote\\n> > machine accepts all connections from Robert, or all connections\\n> > whatsoever, or all connections on Mondays. I just don't know.\\n> \\n> As of SYSTEM_USER, I think this is no longer the case -- after\\n> connection establishment, you can ask the server who was authenticated\\n> and why. (It doesn't explain why you were authorized to be that\\n> particular user, but that seems maybe less important wen you're trying\\n> to disallow ambient authentication.)\\n\\nThere's not enough documentation for SYSTEM_USER imo.\\n\\n\\n\\n> You could even go a step further and disable ambient transport\\n> authentication (sslcertmode=disable gssencmode=disable), which keeps a\\n> proxied connection from making use of a client cert or a Kerberos cache. But\\n> for postgres_fdw, at least, that carries a risk of disabling current use\\n> cases. Stephen and I had a discussion about one such case in the Kerberos\\n> delegation thread [1].\\n\\nI did not find that very convincing for today's code. The likelihood of\\nsomething useful being prevented seems far far lower than preventing privilege\\nleakage...\\n\\n\\n> It doesn't help you if you want to differentiate one form of ambient\\n> auth (trust/peer/etc.) from another, since they look the same to the\\n> protocol. But for e.g. postgres_fdw I'm not sure why you would want to\\n> differentiate between those cases, because they all seem bad.\\n\\nIt might be possible to teach libpq to differentiate peer from trust (by\\ndisabling passing the current user), or we could tell the server via an option\\nto disable peer. But as you say, I don't think it'd buy us much.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 11:05:33 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 1:27 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> On Mon, Jan 23, 2023 at 8:35 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > I will admit that this is not an open-and-shut case, because a\\n> > passwordless login back to the bootstrap superuser account from the\\n> > local machine is a pretty common scenario and doesn't feel\\n> > intrinsically unreasonable to me, and I hadn't thought about that as a\\n> > potential attack vector.\\n>\\n> It seems to me like that's _the_ primary attack vector. I think I\\n> agree with you that the password requirement is an overly large\\n> hammer, but I don't think it's right (or safe/helpful to DBAs reading\\n> along) to describe it as a manufactured concern.\\n\\nFirst, sorry about the wording. I try to get it right, but sometimes I don't.\\n\\nSecond, the reason why I described it as a manufactured issue is\\nbecause it's a bit like asking someone to stand under a ladder and\\nthen complaining when they get hit in the head by a falling object.\\nIt's not that I think it's good for people to get a free exploit to\\nsuperuser, or to get hit in the head by falling objects. It's just\\nthat you can't have the things that together lead to some outcome\\nwithout also getting the outcome. It seems to me that we basically let\\nthe malicious connection to the target host succeed, and then say ...\\noh, never mind, we may have made this connection under false\\npretenses, so we shan't use it after all. What I was attempting to\\nargue is that we shouldn't let things get that far. Either the victim\\nshould be able to protect itself from the malicious connection, or the\\nconnection attempt shouldn't be allowed in the first place, or both.\\nBlocking the connection attempt after the fact feels like too little,\\ntoo late.\\n\\nFor instance, what if the connection string itself caused SQL to be\\nexecuted on the remote side, as in the case of target_session_attrs?\\nOr what if we got those logon triggers that people have been wanting\\nfor years? Or what if the remote server speaks the PostgreSQL protocol\\nbut isn't really PostgreSQL and does ... whatever ... when you just\\nconnect to it?\\n\\n> As of SYSTEM_USER, I think this is no longer the case -- after\\n> connection establishment, you can ask the server who was authenticated\\n> and why. (It doesn't explain why you were authorized to be that\\n> particular user, but that seems maybe less important wen you're trying\\n> to disallow ambient authentication.)\\n\\nI think this is too after-the-fact, as discussed above.\\n\\n> If my require_auth patchset gets in, you'd be able to improve on this\\n> by rejecting all ambient forms of authentication at the protocol level\\n> (require_auth=password,md5,scram-sha-256). You could even go a step\\n> further and disable ambient transport authentication\\n> (sslcertmode=disable gssencmode=disable), which keeps a proxied\\n> connection from making use of a client cert or a Kerberos cache. But\\n> for postgres_fdw, at least, that carries a risk of disabling current\\n> use cases. Stephen and I had a discussion about one such case in the\\n> Kerberos delegation thread [1].\\n\\nYes, this is why I think that the system administrator needs to have\\nsome control over policy, instead of just having a hard-coded rule\\nthat applies to everyone.\\n\\nI'm not completely sure that this is good enough in terms of blocking\\nthe attack as early as I think we should. This is all happening in the\\nmidst of a connection attempt. If the remote server says, \\\"hey, what's\\nyour password?\\\" and we refuse to answer that question, well that seems\\nsomewhat OK. But what if we're hoping to be asked for a password and\\nthe remote server doesn't ask? Then we don't find out that things\\naren't right until after we've already logged in, and that gets back\\nto what I talk about above.\\n\\n> > To put that another way, if I'm making a connection on behalf of an\\n> > untrusted party, I can choose not to supply an SSL certificate, or not\\n> > to supply a password. But I cannot choose to not be myself.\\n>\\n> (IMO, you're driving towards a separation of the proxy identity from\\n> the user identity. Other protocols do that too.)\\n\\nHmm, interesting.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 14:47:06 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 2:47 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> Second, the reason why I described it as a manufactured issue is\\n> because it's a bit like asking someone to stand under a ladder and\\n> then complaining when they get hit in the head by a falling object.\\n> It's not that I think it's good for people to get a free exploit to\\n> superuser, or to get hit in the head by falling objects. It's just\\n> that you can't have the things that together lead to some outcome\\n> without also getting the outcome.\\n\\nI left out a sentence here. What I meant to say was we can't both\\nallow passwordless loopback connections to the bootstrap superuser and\\nalso allow postgres_fdw to connect to anything that the user requests\\nand then be surprised when that user can get into the superuser\\naccount. The natural outcome of combining those two things is that\\nsuperuser gets hacked.\\n\\nThe password requirement just *barely* prevents that attack from\\nworking, almost, maybe, while at the same time managing to block\\nthings that people want to do for totally legitimate reasons. But\\nIMHO, the real problem is that combining those two things is extremely\\ndangerous.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 14:52:25 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, 2023-01-20 at 11:08 -0500, Robert Haas wrote:\\n> On Fri, Jan 20, 2023 at 8:25 AM Robert Haas <robertmhaas@gmail.com>\\n> wrote:\\n> > I still think you're talking about a different problem here. I'm\\n> > talking about the problem of knowing whether local files are going\\n> > to\\n> > be accessed by the connection string.\\n> \\n> So here's a dumb patch for this. At least in my mind, the connection\\n> string sanitization/validation is the major design problem here\\n\\nI believe your patch conflates two use cases:\\n\\n(A) Tightly-coupled servers that are managed by the administrator. In\\nthis case, there are a finite number of connection strings to make, and\\nthe admin knows about all of them. Validation is a poor solution for\\nthis use case, because we get into the weeds trying to figure out\\nwhat's safe or not, overriding the admin's better judgement in some\\ncases and letting through connection strings that might be unsafe. A\\nmuch better solution is to simply declare the connection strings as\\nsome kind of object (perhaps a SERVER object), and hand out privileges\\nor inherit them from a predefined role. Having connection string\\nobjects is also just a better UI: it allows changes to connection\\nstrings over time to adapt to changing security needs, and allows a\\nsimple name that is much easier to type and read.\\n\\n(B) Loosely-coupled servers that the admin doesn't know about, but\\nwhich might be perfectly safe to access. Validation is useful here, but\\nit's a long road of fine-grained privileges around acceptable hosts,\\nIPs, authentication types, file access, password sources, password\\nprotocols, connection options, etc. The right solution here is to\\nidentify the sub-usecases of loosely-coupled servers, and enable them\\n(with the appropriate controls) one at a time. Arguably, that's already\\nwhat's happened by demanding a password (even if we don't like the\\nmechanism, it does seem to work for some important cases).\\n\\nIs your patch targeted at use case (A), (B), or both?\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 12:50:04 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 1/23/23 11:05, Andres Freund wrote:\\n> There's not enough documentation for SYSTEM_USER imo.\\n\\nIf we were to make use of SYSTEM_USER programmatically (and based on\\nwhat Robert wrote downthread, that's probably not what's desired), I\\nthink we'd have to make more guarantees about how it can be parsed and\\nthe values that you can expect. Right now it's meant mostly for human\\nconsumption.\\n\\n>> You could even go a step further and disable ambient transport\\n>> authentication (sslcertmode=disable gssencmode=disable), which keeps a\\n>> proxied connection from making use of a client cert or a Kerberos cache. But\\n>> for postgres_fdw, at least, that carries a risk of disabling current use\\n>> cases. Stephen and I had a discussion about one such case in the Kerberos\\n>> delegation thread [1].\\n> \\n> I did not find that very convincing for today's code. The likelihood of\\n> something useful being prevented seems far far lower than preventing privilege\\n> leakage...\\n\\nFair enough. Preventing those credentials from being pulled in by\\ndefault would effectively neutralize my concern for the delegation\\npatchset, too.\\n\\n--Jacob\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 16:23:52 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 1/23/23 11:52, Robert Haas wrote:\\n> On Mon, Jan 23, 2023 at 2:47 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>> Second, the reason why I described it as a manufactured issue is\\n>> because it's a bit like asking someone to stand under a ladder and\\n>> then complaining when they get hit in the head by a falling object.\\n>> It's not that I think it's good for people to get a free exploit to\\n>> superuser, or to get hit in the head by falling objects. It's just\\n>> that you can't have the things that together lead to some outcome\\n>> without also getting the outcome.\\n>\\n> I left out a sentence here. What I meant to say was we can't both\\n> allow passwordless loopback connections to the bootstrap superuser and\\n> also allow postgres_fdw to connect to anything that the user requests\\n> and then be surprised when that user can get into the superuser\\n> account. The natural outcome of combining those two things is that\\n> superuser gets hacked.\\n>\\n> The password requirement just *barely* prevents that attack from\\n> working, almost, maybe, while at the same time managing to block\\n> things that people want to do for totally legitimate reasons. But\\n> IMHO, the real problem is that combining those two things is extremely\\n> dangerous.\\n\\nI don't disagree. I'm worried that the unspoken conclusion being\\npresented is \\\"it's such an obvious problem that we should just leave it\\nto the DBAs,\\\" which I very much disagree with, but I may be reading too\\nmuch into it.\\n\\n> It seems to me that we basically let\\n> the malicious connection to the target host succeed, and then say ...\\n> oh, never mind, we may have made this connection under false\\n> pretenses, so we shan't use it after all. What I was attempting to\\n> argue is that we shouldn't let things get that far. Either the victim\\n> should be able to protect itself from the malicious connection, or the\\n> connection attempt shouldn't be allowed in the first place, or both.\\n> Blocking the connection attempt after the fact feels like too little,\\n> too late.\\n\\nExpanding on my previous comment, you could give the client a way to say\\n\\\"I am a proxy, and I'm connecting on behalf of this user, and here are\\nboth my credentials and their credentials. So if you were planning to,\\nsay, authorize me as superuser based on my IP address... maybe don't do\\nthat?\\\"\\n\\n(You can sort of implement this today, by giving the proxy a client\\ncertificate for transport authn, having it provide the in-band authn for\\nthe user, and requiring both at the server. It's not very flexible.)\\n\\nI think this has potential overlap with Magnus' PROXY proposal [1], and\\nalso the case where we want pgbouncer to authenticate itself and then\\nperform actions on behalf of someone else [2], and maybe SASL's authzid\\nconcept. I don't think one solution will hit all of the desired use\\ncases, but there are directions that can be investigated.\\n\\n> I'm not completely sure that this is good enough in terms of blocking\\n> the attack as early as I think we should. This is all happening in the\\n> midst of a connection attempt. If the remote server says, \\\"hey, what's\\n> your password?\\\" and we refuse to answer that question, well that seems\\n> somewhat OK. But what if we're hoping to be asked for a password and\\n> the remote server doesn't ask?\\n\\nrequire_auth should still successfully mitigate the target_session_attrs\\ncase (going back to the examples you provided). It looks like the SQL is\\ninitiated from the client side, so require_auth will notice that there\\nwas no authentication performed and bail out before we get there.\\n\\nFor the hypothetical logon trigger, or any case where the server does\\nsomething on behalf of a user upon connection, I agree it doesn't help you.\\n\\n--Jacob\\n\\n[1]\\nhttps://www.postgresql.org/message-id/flat/CABUevExJ0ifpUEiX4uOREy0s2kHBrBrb=pXLEHhpMTR1vVR1XA@mail.gmail.com\\n[2]\\nhttps://www.postgresql.org/message-id/CAMT0RQR2fxeaPLHXappBCGEjHJiPCBJMPOHoDWiaYLjuieR0sg%40mail.gmail.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 23 Jan 2023 16:24:34 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 7:24 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > The password requirement just *barely* prevents that attack from\\n> > working, almost, maybe, while at the same time managing to block\\n> > things that people want to do for totally legitimate reasons. But\\n> > IMHO, the real problem is that combining those two things is extremely\\n> > dangerous.\\n>\\n> I don't disagree. I'm worried that the unspoken conclusion being\\n> presented is \\\"it's such an obvious problem that we should just leave it\\n> to the DBAs,\\\" which I very much disagree with, but I may be reading too\\n> much into it.\\n\\nTo be honest, that was my first instinct here, but I see the problems\\nbetter now than I did at the beginning of this discussion.\\n\\n> Expanding on my previous comment, you could give the client a way to say\\n> \\\"I am a proxy, and I'm connecting on behalf of this user, and here are\\n> both my credentials and their credentials. So if you were planning to,\\n> say, authorize me as superuser based on my IP address... maybe don't do\\n> that?\\\"\\n>\\n> (You can sort of implement this today, by giving the proxy a client\\n> certificate for transport authn, having it provide the in-band authn for\\n> the user, and requiring both at the server. It's not very flexible.)\\n>\\n> I think this has potential overlap with Magnus' PROXY proposal [1], and\\n> also the case where we want pgbouncer to authenticate itself and then\\n> perform actions on behalf of someone else [2], and maybe SASL's authzid\\n> concept. I don't think one solution will hit all of the desired use\\n> cases, but there are directions that can be investigated.\\n\\nI think this has some potential, but it's pretty complex, seeming to\\nrequire protocol extensions and having backward-compatibility problems\\nand so on. What do you think about something in the spirit of a\\nreverse-pg_hba.conf? The idea being that PostgreSQL facilities that\\nmake outbound connections are supposed to ask it whether those\\nconnections are OK to initiate. Then you could have a default\\nconfiguration that basically says \\\"don't allow loopback connections\\\"\\nor \\\"require passwords all the time\\\" or whatever we like, and the DBA\\ncan change that as desired. We could teach dblink, postgres_fdw, and\\nCREATE SUBSCRIPTION to use this new thing, and third-party code could\\nadopt it if it likes.\\n\\nEven if we do that, some kind of proxy protocol support might be very\\ndesirable. I'm not against that. But I think that DBAs need better\\ncontrol over what kind of outbound connections they want to permit,\\ntoo.\\n\\n> For the hypothetical logon trigger, or any case where the server does\\n> something on behalf of a user upon connection, I agree it doesn't help you.\\n\\nI don't think the logon trigger thing is all *that* hypothetical. We\\ndon't have it yet, but there have been patches proposed repeatedly for\\nmany years.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 24 Jan 2023 08:50:42 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\nOn 2023-01-24 Tu 08:50, Robert Haas wrote:\\n>\\n> What do you think about something in the spirit of a\\n> reverse-pg_hba.conf? The idea being that PostgreSQL facilities that\\n> make outbound connections are supposed to ask it whether those\\n> connections are OK to initiate. Then you could have a default\\n> configuration that basically says \\\"don't allow loopback connections\\\"\\n> or \\\"require passwords all the time\\\" or whatever we like, and the DBA\\n> can change that as desired. We could teach dblink, postgres_fdw, and\\n> CREATE SUBSCRIPTION to use this new thing, and third-party code could\\n> adopt it if it likes.\\n>\\n\\nI kinda like this idea, especially if we could specify the context that\\nrules are to apply in. e.g. postgres_fdw, mysql_fdw etc. I'd certainly\\ngive it an outing in the redis_fdw if appropriate.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 24 Jan 2023 12:24:05 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 24, 2023 at 5:50 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> I think this has some potential, but it's pretty complex, seeming to\\n> require protocol extensions and having backward-compatibility problems\\n> and so on.\\n\\nYeah.\\n\\n> What do you think about something in the spirit of a\\n> reverse-pg_hba.conf? The idea being that PostgreSQL facilities that\\n> make outbound connections are supposed to ask it whether those\\n> connections are OK to initiate. Then you could have a default\\n> configuration that basically says \\\"don't allow loopback connections\\\"\\n> or \\\"require passwords all the time\\\" or whatever we like, and the DBA\\n> can change that as desired.\\n\\nWell, I'll have to kick the idea around a little bit. Kneejerk reactions:\\n\\n- It's completely reasonable to let a proxy operator restrict how that\\nproxy is used. I doubt very much that a typical DBA wants to be\\noperating an open proxy.\\n\\n- I think the devil will be in the details of the configuration\\ndesign. Lists of allowed destination authorities (in the URI sense),\\noptions that must be present/absent/overridden, those sound great. But\\nyour initial examples of allow-loopback and require-passwords options\\nare in the \\\"make the DBA deal with it\\\" line of thinking, IMO. I think\\nit's difficult for someone to reason through those correctly the first\\ntime, even for experts. I'd like to instead see the core problem --\\nthat *any* ambient authentication used by a proxy is inherently risky\\n-- exposed as a highly visible concept in the config, so that it's\\nhard to make mistakes.\\n\\n- I'm inherently skeptical of solutions that require all clients --\\nproxies, in this case -- to be configured correctly in order for a\\nserver to be able to protect itself. (But I also have a larger\\nappetite for security options that break compatibility when turned on.\\n:D)\\n\\n> > For the hypothetical logon trigger, or any case where the server does\\n> > something on behalf of a user upon connection, I agree it doesn't help you.\\n>\\n> I don't think the logon trigger thing is all *that* hypothetical. We\\n> don't have it yet, but there have been patches proposed repeatedly for\\n> many years.\\n\\nOkay. I think this thread has applicable lessons -- if connection\\nestablishment itself leads to side effects, all actors in the\\necosystem (bouncers, proxies) have to be hardened against making those\\nconnections passively. I know we're very different from HTTP, but it\\nfeels similar to their concept of method safety and the consequences\\nof violating it.\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Tue, 24 Jan 2023 11:18:44 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"[ Changing subject line to something more appropriate: This is\\nbranched from the \\\"Non-superuser subscription owners\\\" thread, but the\\ntopic has become connection security more generally for outbound\\nconnections from a PostgreSQL instance, the inadequacies of just\\ntrying to require that such connections always use a password, and\\nrelated problems. I proposed some kind of \\\"reverse pg_hba.conf file\\\"\\nas a way of allowing configurable limits on such outbound connections.\\n]\\n\\nOn Tue, Jan 24, 2023 at 2:18 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> - It's completely reasonable to let a proxy operator restrict how that\\n> proxy is used. I doubt very much that a typical DBA wants to be\\n> operating an open proxy.\\n\\nThat's very well put. It's precisely what I was thinking, but\\nexpressed much more clearly.\\n\\n> - I think the devil will be in the details of the configuration\\n> design. Lists of allowed destination authorities (in the URI sense),\\n> options that must be present/absent/overridden, those sound great. But\\n> your initial examples of allow-loopback and require-passwords options\\n> are in the \\\"make the DBA deal with it\\\" line of thinking, IMO. I think\\n> it's difficult for someone to reason through those correctly the first\\n> time, even for experts. I'd like to instead see the core problem --\\n> that *any* ambient authentication used by a proxy is inherently risky\\n> -- exposed as a highly visible concept in the config, so that it's\\n> hard to make mistakes.\\n\\nI find the concept of \\\"ambient authentication\\\" problematic. I don't\\nknow exactly what you mean by it. I hope you'll tell me, but I think\\nthat I won't like it even after I know, because as I said before, it's\\ndifficult to know why anyone else makes a decision, and asking an\\nuntrusted third-party why they're deciding something is sketchy at\\nbest. I think that the problems we have in this area can be solved by\\neither (a) restricting the open proxy to be less open or (b)\\nencouraging people to authenticate users in some way that won't admit\\nconnections from an open proxy. The former needs to be configurable by\\nthe DBA, and the latter is also a configuration choice by the DBA. We\\ncan provide tools here that make it less likely that people will shoot\\nthemselves in the foot, and we can ship default configurations that\\nreduce the chance of inadvertent foot-shooting, and we can write\\ndocumentation that says \\\"don't shoot yourself in the foot,\\\" but we\\ncannot actually prevent people from shooting themselves in the foot\\nexcept, perhaps, by massively nerfing the capabilities of the system.\\n\\nWhat I was thinking about in terms of a \\\"reverse pg_hba.conf\\\" was\\nsomething in the vein of, e.g.:\\n\\nSOURCE_COMPONENT SOURCE_DATABASE SOURCE_USER DESTINATION_SUBNET\\nDESTINATION_DATABASE DESTINATION_USER OPTIONS ACTION\\n\\ne.g.\\n\\nall all all local all all - deny # block access through UNIX sockets\\nall all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\\n\\nOr:\\n\\npostgres_fdw all all all all all authentication=cleartext,md5,sasl\\nallow # allow postgres_fdw with password-ish authentication\\n\\nDisallowing loopback connections feels quite tricky. You could use\\n127.anything.anything.anything, but you could also loop back via IPv6,\\nor you could loop back via any interface. But you can't use\\nsubnet-based ACLs to rule out loop backs through IP/IPv6 interfaces\\nunless you know what all your system's own IPs are. Maybe that's an\\nargument in favor of having a dedicated deny-loopback facility built\\ninto the system instead of relying on IP ACLs. But I am not sure that\\nreally works either: how sure are we that we can discover all of the\\nlocal IP addresses? Maybe it doesn't matter anyway, since the point is\\njust to disallow anything that would be likely to use \\\"trust\\\" or\\n\\\"ident\\\" authentication, and that's probably not going to include any\\nnon-loopback network interfaces. But ... is that true in general? What\\nabout on Windows?\\n\\n> - I'm inherently skeptical of solutions that require all clients --\\n> proxies, in this case -- to be configured correctly in order for a\\n> server to be able to protect itself. (But I also have a larger\\n> appetite for security options that break compatibility when turned on.\\n> :D)\\n\\nI (still) don't think that restricting the proxy is required, but you\\ncan't both not restrict the proxy and also allow passwordless loopback\\nsuperuser connections. You have to pick one or the other. The reason I\\nkeep harping on the role of the DBA is that I don't think we can make\\nthat choice unilaterally on behalf of everyone. We've tried doing that\\nwith the current rules and we've discussed the weaknesses of that\\napproach already.\\n\\n> > I don't think the logon trigger thing is all *that* hypothetical. We\\n> > don't have it yet, but there have been patches proposed repeatedly for\\n> > many years.\\n>\\n> Okay. I think this thread has applicable lessons -- if connection\\n> establishment itself leads to side effects, all actors in the\\n> ecosystem (bouncers, proxies) have to be hardened against making those\\n> connections passively. I know we're very different from HTTP, but it\\n> feels similar to their concept of method safety and the consequences\\n> of violating it.\\n\\nI am not familiar with that concept in detail but that sounds right to me.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 24 Jan 2023 15:04:15 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 23, 2023 at 3:50 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> I believe your patch conflates two use cases:\\n>\\n> (A) Tightly-coupled servers that are managed by the administrator. In\\n> this case, there are a finite number of connection strings to make, and\\n> the admin knows about all of them. Validation is a poor solution for\\n> this use case, because we get into the weeds trying to figure out\\n> what's safe or not, overriding the admin's better judgement in some\\n> cases and letting through connection strings that might be unsafe. A\\n> much better solution is to simply declare the connection strings as\\n> some kind of object (perhaps a SERVER object), and hand out privileges\\n> or inherit them from a predefined role. Having connection string\\n> objects is also just a better UI: it allows changes to connection\\n> strings over time to adapt to changing security needs, and allows a\\n> simple name that is much easier to type and read.\\n>\\n> (B) Loosely-coupled servers that the admin doesn't know about, but\\n> which might be perfectly safe to access. Validation is useful here, but\\n> it's a long road of fine-grained privileges around acceptable hosts,\\n> IPs, authentication types, file access, password sources, password\\n> protocols, connection options, etc. The right solution here is to\\n> identify the sub-usecases of loosely-coupled servers, and enable them\\n> (with the appropriate controls) one at a time. Arguably, that's already\\n> what's happened by demanding a password (even if we don't like the\\n> mechanism, it does seem to work for some important cases).\\n>\\n> Is your patch targeted at use case (A), (B), or both?\\n\\nI suppose that I would say that the patch is a better fit for (B),\\nbecause I'm not proposing to add any kind of intermediate object of\\nthe type you postulate in (A). However, I don't really agree with the\\nway you've split this up, either. It seems to me that the relevant\\nquestion isn't \\\"are the servers tightly coupled?\\\" but rather \\\"could\\nsome user make a mess if we let them use any arbitrary connection\\nstring?\\\".\\n\\nIf you're running all of the machines involved on a private network\\nthat is well-isolated from the Internet and in which only trusted\\nactors operate, you could use what I'm proposing here for either (A)\\nor (B) and it would be totally fine. If your server is sitting out on\\nthe public Internet and is adequately secured against malicious\\nloopback connections, you could also probably use it for either (A) or\\n(B), unless you've got users who are really shady and you're worried\\nthat the outbound connections that they make from your machine might\\nget you into trouble, in which case you probably can't use it for\\neither (A) or (B). Basically, the patch is suitable for cases where\\nyou don't really need to restrict what connection strings people can\\nuse, and unsuitable for cases where you do, but that doesn't have much\\nto do with whether the servers involved are loosely or tightly\\ncoupled.\\n\\nI think that you're basically trying to make an argument that some\\nsort of complex outbound connection filtering is mandatory, and I\\nstill don't really agree with that. We ship postgres_fdw with\\nsomething extremely minimal - just a requirement that the password get\\nused - and the same for dblink. I think those rules suck and are\\nprobably bad and insecure in quite a number of cases, and overly\\nstrict in others, but I can think of no reason why CREATE SUBSCRIPTION\\nshould be held to a higher standard than anything else. The\\nconnections that you can make using CREATE SUBSCRIPTION are strictly\\nweaker than the ones you can make with dblink, which permits arbitrary\\nSQL execution. It cannot be right to suppose that a less-exploitable\\nsystem needs to be held to a higher security standard than a similar\\nbut more-exploitable system.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 24 Jan 2023 17:00:52 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 1/24/23 12:04, Robert Haas wrote:\\n> I find the concept of \\\"ambient authentication\\\" problematic. I don't\\n> know exactly what you mean by it. I hope you'll tell me,\\n\\nSure: Ambient authority [1] means that something is granted access based\\non some aspect of its existence that it can't remove (or even\\nnecessarily enumerate). Up above, when you said \\\"I cannot choose not to\\nbe myself,\\\" that's a clear marker that ambient authority is involved.\\nExamples of ambient authn/z factors might include an originating IP\\naddress, the user ID of a connected peer process, the use of a loopback\\ninterface, a GPS location, and so on. So 'peer' and 'ident' are ambient\\nauthentication methods.\\n\\nAnd, because I think it's useful, I'll extend the definition to include\\nprivileges that _could_ be dropped by a proxy, but in practice are\\nincluded because there's no easy way not to. Examples for libpq include\\nthe automatic use of the client certificate in ~/.postgresql, or any\\nKerberos credentials available in the local user cache. (Or even a\\nPGPASSWORD set up and forgotten by a DBA.)\\n\\nAmbient authority is closely related to the confused deputy problem [2],\\nand the proxy discussed here is a classic confused deputy. The proxy\\ndoesn't know that a core piece of its identity has been used to\\nauthenticate the request it's forwarding. It can't choose its IP\\naddress, or its user ID.\\n\\nI'm most familiar with this in the context of HTTP, cookie-/IP-based\\nauthn, and cross-site request forgeries. Whenever someone runs a local\\nweb server with no authentication and says \\\"it's okay! we only respond\\nto requests from the local host!\\\" they're probably about to be broken\\nopen by the first person to successfully reflect a request through the\\nvictim's (very local) web browser.\\n\\nWays to mitigate or solve this problem (that I know of) include\\n\\n1) Forwarding the original ambient context along with the request, so\\nthe server can check it too. HTTP has the Origin header, so a browser\\ncan say, \\\"This request is not coming from my end user; it's coming from\\na page controlled by example.org. You can't necessarily treat attached\\ncookies like they're authoritative.\\\" The PROXY protocol lets a proxy\\nforward several ambient factors, including the originating IP address\\n(or even the use of a UNIX socket) and information about the original\\nTLS context.\\n\\n2) Explicitly combining the request with the proof of authority needed\\nto make it, as in capability-based security [3]. Some web frameworks\\npush secret \\\"CSRF tokens\\\" into URLs for this purpose, to tangle the\\nauthorization into the request itself [4]. I'd argue that the \\\"password\\nrequirement\\\" implemented by postgres_fdw and discussed upthread was an\\nattempt at doing this, to try to ensure that the authentication comes\\nfrom the user explicitly and not from the proxy. It's just not very strong.\\n\\n(require_auth would strengthen it quite a bit; a major feature of that\\npatchset is to explicitly name the in-band authentication factors that a\\nserver is allowed to pull out of a client. It's still not strong enough\\nto make a true capability, for one because it's client-side only. But as\\nlong as servers don't perform actions on behalf of users upon\\nconnection, that's pretty good in practice.)\\n\\n3) Dropping as many implicitly-held privileges as possible before making\\na request. This doesn't solve the problem but may considerably reduce\\nthe practical attack surface. For example, if browsers didn't attach\\ntheir user's cookies to cross-origin requests, cross-site request\\nforgeries would probably be considerably less dangerous (and, in the\\nyears since I left the space, it looks like browsers have finally\\nstopped doing this by default). Upthread, Andres suggested disabling the\\ndefault inclusion of client certs and GSS creds, and I would extend that\\nto include really *anything* pulled in from the environment. Make the\\nDBA explicitly allow those things.\\n\\n> but I think\\n> that I won't like it even after I know, because as I said before, it's\\n> difficult to know why anyone else makes a decision, and asking an\\n> untrusted third-party why they're deciding something is sketchy at\\n> best.\\n\\nI think that's a red herring. Setting aside that you can, in fact, prove\\nthat the server has authenticated you (e.g. require_auth=scram-sha-256\\nin my proposed patchset), I don't think \\\"untrusted servers, that we\\ndon't control, doing something stupid\\\" is a very useful thing to focus\\non. We're trying to secure the case where a server *is* authenticating\\nus, using known useful factors, but those factors have been co-opted by\\nan attacker via a proxy.\\n\\n> I think that the problems we have in this area can be solved by\\n> either (a) restricting the open proxy to be less open or (b)\\n> encouraging people to authenticate users in some way that won't admit\\n> connections from an open proxy.\\n\\n(a) is an excellent mitigation, and we should do it. (b) starts getting\\nshaky because I think peer auth is actually a very reasonable choice for\\nmany people. So I hope we can also start solving the underlying problem\\nwhile we implement (a).\\n\\n> we\\n> cannot actually prevent people from shooting themselves in the foot\\n> except, perhaps, by massively nerfing the capabilities of the system.\\n\\nBut I thought we already agreed that most DBAs do not want a massively\\ncapable proxy? I don't think we have to massively nerf the system, but\\nlet's say we did. Would that really be unacceptable for this use case?\\n\\n(You're still driving hard down the \\\"it's impossible for us to securely\\nhandle both cases at the same time\\\" path. I don't think that's true from\\na technical standpoint, because we hold nearly total control of the\\nprotocol. I think we're in a much easier situation than HTTP was.)\\n\\n> What I was thinking about in terms of a \\\"reverse pg_hba.conf\\\" was\\n> something in the vein of, e.g.:\\n> \\n> SOURCE_COMPONENT SOURCE_DATABASE SOURCE_USER DESTINATION_SUBNET\\n> DESTINATION_DATABASE DESTINATION_USER OPTIONS ACTION\\n> \\n> e.g.\\n> \\n> all all all local all all - deny # block access through UNIX sockets\\n> all all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\\n> \\n> Or:\\n> \\n> postgres_fdw all all all all all authentication=cleartext,md5,sasl\\n> allow # allow postgres_fdw with password-ish authentication\\n\\nI think this style focuses on absolute configuration flexibility at the\\nexpense of usability. It obfuscates the common use cases. (I have the\\nexact same complaint about our HBA and ident configs, so I may be\\nfighting uphill.)\\n\\nHow should a DBA decide what is correct, or audit a configuration they\\ninherited from someone else? What makes it obvious why a proxy should\\nrequire cleartext auth instead of peer auth (especially since peer auth\\nseems to be inherently better, until you've read this thread)?\\n\\nI'd rather the configuration focus on the pieces of a proxy's identity\\nthat can be assumed by a client. For example, if the config has an\\noption for \\\"let a client steal the proxy's user ID\\\", and it's off by\\ndefault, then we've given the problem a name. DBAs can educate\\nthemselves on it.\\n\\nAnd if that option is off, then the implementation knows that\\n\\n1) If the client has supplied explicit credentials and we can force the\\nserver to use them, we're safe.\\n2) If the DBA says they're not running an ident server, or we can force\\nthe server not to use ident authn, or the DBA pinky-swears that that\\nserver isn't using ident authn, all IP connections are additionally safe.\\n3) If we have a way to forward the client's \\\"origin\\\" and we know that\\nthe server will pay attention to it, all UNIX socket connections are\\nadditionally safe.\\n4) Any *future* authentication method we add later needs to be\\nrestricted in the same way.\\n\\nShould we allow the use of our default client cert? the Kerberos cache?\\npasswords from the environment? All these are named and off by default.\\nDBAs can look through those options and say \\\"oh, yeah, that seems like a\\nreally bad idea because we have this one server over here...\\\" And we\\n(the experts) now get to make the best decisions we can, based on a\\nDBA's declared intent, so the implementation gets to improve over time.\\n> Disallowing loopback connections feels quite tricky. You could use\\n> 127.anything.anything.anything, but you could also loop back via IPv6,\\n> or you could loop back via any interface. But you can't use\\n> subnet-based ACLs to rule out loop backs through IP/IPv6 interfaces\\n> unless you know what all your system's own IPs are. Maybe that's an\\n> argument in favor of having a dedicated deny-loopback facility built\\n> into the system instead of relying on IP ACLs. But I am not sure that\\n> really works either: how sure are we that we can discover all of the\\n> local IP addresses?\\n\\nWell, to follow you down that road a little bit, I think that a DBA that\\nhas set up `samehost ... trust` in their HBA is going to expect a\\ncorresponding concept here, and it seems important for us to use an\\nidentical implementation of samehost and samenet.\\n\\nBut I don't really want to follow you down that road, because I think\\nyou illustrated my point yourself. You're already thinking about making\\nDisallowing Loopback Connections a first-class concept, but then you\\nimmediately said\\n\\n> Maybe it doesn't matter anyway, since the point is\\n> just to disallow anything that would be likely to use \\\"trust\\\" or\\n> \\\"ident\\\" authentication\\n\\nI'd rather we enshrine that -- the point -- in the configuration, and\\nhave the proxy disable everything that can't provably meet that intent.\\n\\nThanks,\\n--Jacob\\n\\n[1] https://en.wikipedia.org/wiki/Ambient_authority\\n[2] https://en.wikipedia.org/wiki/Confused_deputy_problem\\n[3] https://en.wikipedia.org/wiki/Capability-based_security\\n[4] https://www.rfc-editor.org/rfc/rfc6265#section-8.2\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Jan 2023 15:22:02 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Tue, 2023-01-24 at 17:00 -0500, Robert Haas wrote:\\n> It seems to me that the relevant\\n> question isn't \\\"are the servers tightly coupled?\\\" but rather \\\"could\\n> some user make a mess if we let them use any arbitrary connection\\n> string?\\\".\\n\\nThe split I created is much easier for an admin to answer: is the list\\nof servers finite, or can users connect to new servers the admin isn't\\neven aware of? If it's a finite list, I feel there's a much better\\nsolution with both security and UI benefits.\\n\\nWith your question, I'm not entirely clear if that's a question that we\\nalready have an answer for (require a password parameter), or that we\\nwill answer in this thread, or that the admin will answer.\\n\\n> unless you've got users who are really shady \\n\\nOr compromised. Unfortunately, a role that's creating subscriptions has\\na lot of surface area for escalation-of-privilege attacks, because they\\nhave to trust all the owners of all the tables the subscriptions write\\nto.\\n\\n\\n> I think that you're basically trying to make an argument that some\\n> sort of complex outbound connection filtering is mandatory\\n\\nNo, I'm not asking for the validation to be more complex.\\n\\nI believe use case (A) is a substantial use case, and I'd like to leave\\nspace in the user interface to solve it a much better way than\\nconnection string validation can offer. But to solve use case (A), we\\nneed to separate the ability to create a subscription from the ability\\nto create a connection string.\\n\\nRight now you see those as the same because they are done at the same\\ntime in the same command; but I don't see it that way, because I had\\nplans to allow a variant of CREATE SUBSCRIPTION that uses foreign\\nservers. That plan would be consistent with dblink and postgres_fdw,\\nwhich already allow specifying foreign servers.\\n\\nI propose that we have two predefined roles: pg_create_subscription,\\nand pg_create_connection. If creating a subscription with a connection\\nstring, you'd need to be a member of both roles. But to create a\\nsubscription with a server object, you'd just need to be a member of\\npg_create_subscription and have the USAGE privilege on the server\\nobject.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Jan 2023 19:45:09 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 25, 2023 at 10:45 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> I propose that we have two predefined roles: pg_create_subscription,\\n> and pg_create_connection. If creating a subscription with a connection\\n> string, you'd need to be a member of both roles. But to create a\\n> subscription with a server object, you'd just need to be a member of\\n> pg_create_subscription and have the USAGE privilege on the server\\n> object.\\n\\nI have no issue with that as a long-term plan. However, I think that\\nfor right now we should just introduce pg_create_subscription. It\\nwould make sense to add pg_create_connection in the same patch that\\nadds a CREATE CONNECTION command (or whatever exact syntax we end up\\nwith) -- and that patch can also change CREATE SUBSCRIPTION to require\\nboth privileges where a connection string is specified directly.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 26 Jan 2023 09:43:09 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-01-26 at 09:43 -0500, Robert Haas wrote:\\n> I have no issue with that as a long-term plan. However, I think that\\n> for right now we should just introduce pg_create_subscription. It\\n> would make sense to add pg_create_connection in the same patch that\\n> adds a CREATE CONNECTION command (or whatever exact syntax we end up\\n> with) -- and that patch can also change CREATE SUBSCRIPTION to\\n> require\\n> both privileges where a connection string is specified directly.\\n\\nI assumed it would be a problem to say that pg_create_subscription was\\nenough to create a subscription today, and then later require\\nadditional privileges (e.g. pg_create_connection).\\n\\nIf that's not a problem, then this sounds fine with me.\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 26 Jan 2023 09:36:11 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 26, 2023 at 12:36 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Thu, 2023-01-26 at 09:43 -0500, Robert Haas wrote:\\n> > I have no issue with that as a long-term plan. However, I think that\\n> > for right now we should just introduce pg_create_subscription. It\\n> > would make sense to add pg_create_connection in the same patch that\\n> > adds a CREATE CONNECTION command (or whatever exact syntax we end up\\n> > with) -- and that patch can also change CREATE SUBSCRIPTION to\\n> > require\\n> > both privileges where a connection string is specified directly.\\n>\\n> I assumed it would be a problem to say that pg_create_subscription was\\n> enough to create a subscription today, and then later require\\n> additional privileges (e.g. pg_create_connection).\\n>\\n> If that's not a problem, then this sounds fine with me.\\n\\nWonderful! I'm working on a patch, but due to various distractions,\\nit's not done yet.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 26 Jan 2023 15:55:13 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 19, 2023 at 8:46 PM Andres Freund <andres@anarazel.de> wrote:\\n> > If we already had (or have) that logic someplace else, it would\\n> > probably make sense to reuse it\\n>\\n> We hve. See at least postgres_fdw's check_conn_params(), dblink's\\n> dblink_connstr_check() and dblink_security_check().\\n\\nIn the patch I posted previously, I had some other set of checks, more\\nor less along the lines suggested by Jeff. I looked into revising that\\napproach and making the behavior match exactly what we do in those\\nplaces instead. I find that it breaks 027_nosuperuser.pl.\\nSpecifically, where without the patch I get \\\"ok 6 - nosuperuser admin\\nwith all table privileges can replicate into unpartitioned\\\", with the\\npatch it goes boom, because the subscription can't connect any more\\ndue to the password requirement.\\n\\nAt first, I found it a bit tempting to see this as a further\\nindication that the force-a-password approach is not the right idea,\\nbecause the test case clearly memorializes a desire *not* to require a\\npassword in this situation. However, the loopback-to-superuser attack\\nis just as viable for subscription as it in other cases, and my\\nprevious patch would have done nothing to block it. So what I did\\ninstead is add a password_required attribute, just like what\\npostgres_fdw has. As in the case of postgres_fdw, the actual rule is\\nthat if the attribute is false, a password is not required, and if the\\nattribute is true, a password is required unless you are a superuser.\\nIf you're a superuser, it still isn't. This is a slightly odd set of\\nsemantics but it has precedent and practical advantages. Also, as in\\nthe case of postgres_fdw, only a superuser can set\\npassword_required=false, and a subscription that has that setting can\\nonly be modified by a superuser, no matter who owns it.\\n\\nEven though I hate the require-a-password stuff with the intensity of\\na thousand suns, I think this is better than the previous patch,\\nbecause it's more consistent with what we do elsewhere and because it\\nblocks the loopback-connection-to-superuser attack. I think we\\n*really* need to develop a better system for restricting proxied\\nconnections (no matter how proxied) and I hope that we do that soon.\\nBut inventing something for this purpose that differs from what we do\\nelsewhere will make that task harder, not easier.\\n\\nThoughts?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Fri, 27 Jan 2023 14:42:01 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 25, 2023 at 6:22 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> Sure: Ambient authority [1] means that something is granted access based\\n> on some aspect of its existence that it can't remove (or even\\n> necessarily enumerate). Up above, when you said \\\"I cannot choose not to\\n> be myself,\\\" that's a clear marker that ambient authority is involved.\\n> Examples of ambient authn/z factors might include an originating IP\\n> address, the user ID of a connected peer process, the use of a loopback\\n> interface, a GPS location, and so on. So 'peer' and 'ident' are ambient\\n> authentication methods.\\n\\nOK.\\n\\n> 1) Forwarding the original ambient context along with the request, so\\n> the server can check it too.\\n\\nRight, so a protocol extension. Reasonable idea, but a big lift. Not\\nonly do you need everyone to be running a new enough version of\\nPostgreSQL, but existing proxies like pgpool and pgbouncer need\\nupdates, too.\\n\\n> 2) Explicitly combining the request with the proof of authority needed\\n> to make it, as in capability-based security [3].\\n\\nAs far as I can see, that link doesn't address how you'd make this\\napproach work across a network.\\n\\n> 3) Dropping as many implicitly-held privileges as possible before making\\n> a request. This doesn't solve the problem but may considerably reduce\\n> the practical attack surface.\\n\\nRight. I definitely don't object to this kind of approach, but I don't\\nthink it can ever be sufficient by itself.\\n\\n> > e.g.\\n> >\\n> > all all all local all all - deny # block access through UNIX sockets\\n> > all all all 127.0.0.0/8 all all - deny # block loopback interface via IPv4\\n> >\\n> > Or:\\n> >\\n> > postgres_fdw all all all all all authentication=cleartext,md5,sasl\\n> > allow # allow postgres_fdw with password-ish authentication\\n>\\n> I think this style focuses on absolute configuration flexibility at the\\n> expense of usability. It obfuscates the common use cases. (I have the\\n> exact same complaint about our HBA and ident configs, so I may be\\n> fighting uphill.)\\n\\nThat's probably somewhat true, but on the other hand, it also is more\\npowerful than what you're describing. In your system, is there some\\nway the DBA can say \\\"hey, you can connect to any of the machines on\\nthis list of subnets, but nothing else\\\"? Or equally, \\\"hey, you may NOT\\nconnect to any machine on this list of subnets, but anything else is\\nfine\\\"? Or \\\"you can connect to these subnets without SSL, but if you\\nwant to talk to anything else, you need to use SSL\\\"? I would feel a\\nbit bad saying that those are just use cases we don't care about. Most\\npeople likely wouldn't use that kind of flexibility, so maybe it\\ndoesn't really matter, but it seems kind of nice to have. Your idea\\nseems to rely on us being able to identify all of the policies that a\\nuser is likely to want and give names to each one, and I don't feel\\nvery confident that that's realistic. But maybe I'm misinterpreting\\nyour idea?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 27 Jan 2023 16:08:38 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-27 14:42:01 -0500, Robert Haas wrote:\\n> At first, I found it a bit tempting to see this as a further\\n> indication that the force-a-password approach is not the right idea,\\n> because the test case clearly memorializes a desire *not* to require a\\n> password in this situation. However, the loopback-to-superuser attack\\n> is just as viable for subscription as it in other cases, and my\\n> previous patch would have done nothing to block it.\\n\\nHm, compared to postgres_fdw, the user has far less control over what's\\nhappening using that connection. Is there a way a subscription owner can\\ntrigger evaluation of near-arbitrary SQL on the publisher side?\\n\\n\\n> So what I did instead is add a password_required attribute, just like what\\n> postgres_fdw has. As in the case of postgres_fdw, the actual rule is that if\\n> the attribute is false, a password is not required, and if the attribute is\\n> true, a password is required unless you are a superuser. If you're a\\n> superuser, it still isn't. This is a slightly odd set of semantics but it\\n> has precedent and practical advantages. Also, as in the case of\\n> postgres_fdw, only a superuser can set password_required=false, and a\\n> subscription that has that setting can only be modified by a superuser, no\\n> matter who owns it.\\n\\nI started out asking what benefits it provides to own a subscription one\\ncannot modify. But I think it is a good capability to have, to restrict the\\nset of relations that replication could target. Although perhaps it'd be\\nbetter to set the \\\"replay user\\\" as a separate property on the subscription?\\n\\nDoes owning a subscription one isn't allowed to modify useful outside of that?\\n\\n\\n\\n> Even though I hate the require-a-password stuff with the intensity of\\n> a thousand suns, I think this is better than the previous patch,\\n> because it's more consistent with what we do elsewhere and because it\\n> blocks the loopback-connection-to-superuser attack. I think we\\n> *really* need to develop a better system for restricting proxied\\n> connections (no matter how proxied) and I hope that we do that soon.\\n> But inventing something for this purpose that differs from what we do\\n> elsewhere will make that task harder, not easier.\\n> \\n> Thoughts?\\n\\nI think it's reasonable to mirror behaviour from elsewhere, and it'd let us\\nhave this feature relatively soon - I think it's a common need to do this as a\\nnon-superuser. It's IMO a very good idea to not subscribe as a superuser, even\\nif set up by a superuser...\\n\\nBut I also would understand if you / somebody else chose to focus on\\nimplementing a less nasty connection model.\\n\\n\\n> Subject: [PATCH v2] Add new predefined role pg_create_subscriptions.\\n\\nMaybe a daft question:\\n\\nHave we considered using a \\\"normal grant\\\", e.g. on the database, instead of a\\nrole? Could it e.g. be useful to grant a user the permission to create a\\nsubscription in one database, but not in another?\\n\\n\\n> @@ -1039,6 +1082,16 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,\\n> \\n> \\tsub = GetSubscription(subid, false);\\n> \\n> +\\t/*\\n> +\\t * Don't allow non-superuser modification of a subscription with\\n> +\\t * password_required=false.\\n> +\\t */\\n> +\\tif (!sub->passwordrequired && !superuser())\\n> +\\t\\tereport(ERROR,\\n> +\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n> +\\t\\t\\t\\t\\t\\t errmsg(\\\"password_required=false is superuser-only\\\"),\\n> +\\t\\t\\t\\t\\t\\t errhint(\\\"Subscriptions with the password_required option set to false may only be created or modified by the superuser.\\\")));\\n> +\\n> \\t/* Lock the subscription so nobody else can do anything with it. */\\n> \\tLockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);\\n\\nThe subscription code already does ownership checks before locking and now\\nthere's also the passwordrequired before. Is it possible that this could open\\nup some sort of race? Could e.g. the user change the ownership to the\\nsuperuser in one session, do an ALTER in the other?\\n\\nIt looks like your change won't increase the danger of that, as the\\nsuperuser() check just checks the current users permissions.\\n\\n\\n> @@ -180,6 +180,13 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,\\n> \\tif (PQstatus(conn->streamConn) != CONNECTION_OK)\\n> \\t\\tgoto bad_connection_errmsg;\\n> \\n> +\\tif (must_use_password && !PQconnectionUsedPassword(conn->streamConn))\\n> +\\t\\tereport(ERROR,\\n> +\\t\\t\\t\\t(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),\\n> +\\t\\t\\t\\t errmsg(\\\"password is required\\\"),\\n> +\\t\\t\\t\\t errdetail(\\\"Non-superuser cannot connect if the server does not request a password.\\\"),\\n> +\\t\\t\\t\\t errhint(\\\"Target server's authentication method must be changed.\\\")));\\n> +\\n\\nThe documentation of libpqrcv_connect() says that:\\n * Returns NULL on error and fills the err with palloc'ed error message.\\n\\nand throwing an error like that will at the very least leak the connection,\\nfd, fd reservation. Which I just had fixed :). At the very least you'd need to\\ncopy the stuff that \\\"bad_connection:\\\" does.\\n\\n\\nI did wonder whether we should make libpqrcv_connect() use errsave() to return\\nerrors. Or whether we should make libpqrcv register a memory context reset\\ncallback that'd close the libpq connection.\\n\\n\\n> /*\\n> - * Validate connection info string (just try to parse it)\\n> + * Validate connection info string, and determine whether it might cause\\n> + * local filesystem access to be attempted.\\n> + *\\n> + * If the connection string can't be parsed, this function will raise\\n> + * an error and will not return. If it can, it will return true if this\\n> + * connection string specifies a password and false otherwise.\\n> */\\n> -static void\\n> +static bool\\n> libpqrcv_check_conninfo(const char *conninfo)\\n\\nThat is a somewhat odd API. Why does it throw for some things, but not\\nothers? Seems a bit cleaner to pass in a parameter indicating whether it\\nshould throw when not finding a password? Particularly because you already\\npass that to walrcv_connect().\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Fri, 27 Jan 2023 13:09:11 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 27, 2023 at 4:09 PM Andres Freund <andres@anarazel.de> wrote:\\n> Hm, compared to postgres_fdw, the user has far less control over what's\\n> happening using that connection. Is there a way a subscription owner can\\n> trigger evaluation of near-arbitrary SQL on the publisher side?\\n\\nI'm not aware of one, but what I think it would let you do is\\nexfiltrate data you're not entitled to see.\\n\\n> I started out asking what benefits it provides to own a subscription one\\n> cannot modify. But I think it is a good capability to have, to restrict the\\n> set of relations that replication could target. Although perhaps it'd be\\n> better to set the \\\"replay user\\\" as a separate property on the subscription?\\n\\nThat's been proposed previously, but for reasons I don't quite\\nremember it seems not to have happened. I don't think it achieved\\nconsensus.\\n\\n> Does owning a subscription one isn't allowed to modify useful outside of that?\\n\\nUh, possibly that's a question for Mark or Jeff. I don't know. I can't\\nsee what they would be, but I just work here.\\n\\n> Maybe a daft question:\\n>\\n> Have we considered using a \\\"normal grant\\\", e.g. on the database, instead of a\\n> role? Could it e.g. be useful to grant a user the permission to create a\\n> subscription in one database, but not in another?\\n\\nPotentially, but I didn't think we'd want to burn through permissions\\nbits that fast, even given 7b378237aa805711353075de142021b1d40ff3b0.\\nStill, if the consensus is otherwise, I can change it. Then I guess\\nwe'd end up with GRANT CREATE ON DATABASE and GRANT CREATE\\nSUBSCRIPTION ON DATABASE, which I'm sure wouldn't be confusing at all.\\n\\nOr, another thought, maybe this should be checking for CREATE on the\\ncurrent database + also pg_create_subscription. That seems like it\\nmight be the right idea, actually.\\n\\n> The subscription code already does ownership checks before locking and now\\n> there's also the passwordrequired before. Is it possible that this could open\\n> up some sort of race? Could e.g. the user change the ownership to the\\n> superuser in one session, do an ALTER in the other?\\n>\\n> It looks like your change won't increase the danger of that, as the\\n> superuser() check just checks the current users permissions.\\n\\nI'm not entirely clear whether there's a hazard there. If there is, I\\nthink we could fix it by moving the LockSharedObject call up higher,\\nabove object_ownercheck. The only problem with that is it lets you\\nlock an object on which you have no permissions: see\\n2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd\\nneed an analogue of RangeVarGetRelidExtended.\\n\\n> and throwing an error like that will at the very least leak the connection,\\n> fd, fd reservation. Which I just had fixed :). At the very least you'd need to\\n> copy the stuff that \\\"bad_connection:\\\" does.\\n\\nOK.\\n\\n> I did wonder whether we should make libpqrcv_connect() use errsave() to return\\n> errors. Or whether we should make libpqrcv register a memory context reset\\n> callback that'd close the libpq connection.\\n\\nYeah. Using errsave() might be better, but not sure I want to tackle\\nthat just now.\\n\\n> That is a somewhat odd API. Why does it throw for some things, but not\\n> others? Seems a bit cleaner to pass in a parameter indicating whether it\\n> should throw when not finding a password? Particularly because you already\\n> pass that to walrcv_connect().\\n\\nWill look into that.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 27 Jan 2023 16:35:11 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-27 16:35:11 -0500, Robert Haas wrote:\\n> > Maybe a daft question:\\n> >\\n> > Have we considered using a \\\"normal grant\\\", e.g. on the database, instead of a\\n> > role? Could it e.g. be useful to grant a user the permission to create a\\n> > subscription in one database, but not in another?\\n> \\n> Potentially, but I didn't think we'd want to burn through permissions\\n> bits that fast, even given 7b378237aa805711353075de142021b1d40ff3b0.\\n> Still, if the consensus is otherwise, I can change it.\\n\\nI don't really have an opinion on what's better. I looked briefly whether\\nthere was discussion around ithis but I didn't see anything.\\n\\npg_create_subcription feels a bit different than most of the other pg_*\\nroles. For most of those there is no schema object to tie permissions to. But\\nhere there is.\\n\\nBut I think there's good arguments against a GRANT approach, too. GRANT ALL ON\\nDATABASE would suddenly be dangerous. How does it interact with database\\nownership? Etc.\\n\\n\\n> Then I guess we'd end up with GRANT CREATE ON DATABASE and GRANT CREATE\\n> SUBSCRIPTION ON DATABASE, which I'm sure wouldn't be confusing at all.\\n\\nHeh. I guess it could just be GRANT SUBSCRIBE.\\n\\n\\n\\n> Or, another thought, maybe this should be checking for CREATE on the\\n> current database + also pg_create_subscription. That seems like it\\n> might be the right idea, actually.\\n\\nYes, that seems like a good idea.\\n\\n\\n\\n> > The subscription code already does ownership checks before locking and now\\n> > there's also the passwordrequired before. Is it possible that this could open\\n> > up some sort of race? Could e.g. the user change the ownership to the\\n> > superuser in one session, do an ALTER in the other?\\n> >\\n> > It looks like your change won't increase the danger of that, as the\\n> > superuser() check just checks the current users permissions.\\n> \\n> I'm not entirely clear whether there's a hazard there.\\n\\nI'm not at all either. It's just a code pattern that makes me anxious - I\\nsuspect there's a few places it makes us more vulnerable.\\n\\n\\n> If there is, I think we could fix it by moving the LockSharedObject call up\\n> higher, above object_ownercheck. The only problem with that is it lets you\\n> lock an object on which you have no permissions: see\\n> 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\\n> analogue of RangeVarGetRelidExtended.\\n\\nYea, we really should have something like RangeVarGetRelidExtended() for other\\nkinds of objects. It'd take a fair bit of work / time to use it widely, but\\nit'll take even longer if we start in 5 years ;)\\n\\nPerhaps the bulk of RangeVarGetRelidExtended() could be generalized by having\\na separate name->oid lookup callback?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Fri, 27 Jan 2023 14:00:35 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 27, 2023, at 1:35 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n>> I started out asking what benefits it provides to own a subscription one\\n>> cannot modify. But I think it is a good capability to have, to restrict the\\n>> set of relations that replication could target. Although perhaps it'd be\\n>> better to set the \\\"replay user\\\" as a separate property on the subscription?\\n> \\n> That's been proposed previously, but for reasons I don't quite\\n> remember it seems not to have happened. I don't think it achieved\\n> consensus.\\n> \\n>> Does owning a subscription one isn't allowed to modify useful outside of that?\\n> \\n> Uh, possibly that's a question for Mark or Jeff. I don't know. I can't\\n> see what they would be, but I just work here.\\n\\nIf the owner cannot modify the subscription, then the owner degenerates into a mere \\\"run-as\\\" user. Note that this isn't how things work now, and even if we disallowed owners from modifying the connection string, there would still be other attributes the owner could modify, such as the set of publications subscribed.\\n\\n\\nMore generally, my thinking on this thread is that there needs to be two nosuperuser roles: A higher privileged role which can create a subscription, and a lower privileged role serving the \\\"run-as\\\" function. Those shouldn't be the same, because the \\\"run-as\\\" concept doesn't logically need to have subscription creation power, and likely *shouldn't* have that power. Depending on which sorts of attributes a subscription object has, such as the connection string, the answer differs for whether the owner/\\\"run-as\\\" user should get to change those attributes. One advantage of Jeff's idea of using a server object rather than a string is that it becomes more plausibly safe to allow the subscription owner to make changes to that attribute of the subscription.\\n\\n\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 27 Jan 2023 14:56:04 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 27, 2023 at 5:56 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> If the owner cannot modify the subscription, then the owner degenerates into a mere \\\"run-as\\\" user. Note that this isn't how things work now, and even if we disallowed owners from modifying the connection string, there would still be other attributes the owner could modify, such as the set of publications subscribed.\\n\\nThe proposed patch blocks every form of ALTER SUBSCRIPTION if\\npassword_required false is set and you aren't a superuser. Is there\\nsome other DML command that could be used to modify the set of\\npublications subscribed?\\n\\n> More generally, my thinking on this thread is that there needs to be two nosuperuser roles: A higher privileged role which can create a subscription, and a lower privileged role serving the \\\"run-as\\\" function. Those shouldn't be the same, because the \\\"run-as\\\" concept doesn't logically need to have subscription creation power, and likely *shouldn't* have that power. Depending on which sorts of attributes a subscription object has, such as the connection string, the answer differs for whether the owner/\\\"run-as\\\" user should get to change those attributes. One advantage of Jeff's idea of using a server object rather than a string is that it becomes more plausibly safe to allow the subscription owner to make changes to that attribute of the subscription.\\n\\nThere's some question in my mind about what these different mechanisms\\nare intended to accomplish.\\n\\nOn a technical level, I think that the idea of having a separate\\nobjection for the connection string vs. the subscription itself is\\nperfectly sound, and to repeat what I said earlier, if someone wants\\nto implement that, cool. I also agree that it has the advantage that\\nyou specify, namely, that someone can have rights to modify one of\\nthose objects but not the other. What that lets you do is define a\\nshort list of known systems and say, hey, you can replicate whatever\\ntables you want with whatever options you want, but only between these\\nsystems. I'm not quite sure what problem that solves, though.\\n\\n From my point of view, the two things that the superuser is most\\nlikely to want to do are (1) control the replication setup themselves\\nand delegate nothing to any non-superuser or (2) give a non-superuser\\npretty much complete control over replication with just enough\\nrestrictions to avoid letting them do things that would compromise\\nsecurity, such as hacking the local superuser account. In other words,\\nI expect that delegation of the logical replication configuration is\\nusually going to be all or nothing. Jeff's system allows for a\\nsituation where you want to delegate some stuff but not everything,\\nand specifically where you want to dedicate control over the\\nsubscription options and the tables being replicated, but not the\\nconnection strings. To me, that feels like a bit of an awkward\\nconfiguration; I don't really understand in what situation that\\ndivision of responsibility would be particularly useful. I trust that\\nJeff is proposing it because he knows of such a situation, but I don't\\nknow what it is. I feel like, even if I wanted to let people use some\\nconnection strings and not others, I'd probably want that control in\\nsome form other than listing a specific list of allowable connection\\nstrings -- I'd want to say things like \\\"you have to use SSL\\\" or \\\"no\\nconnecting back to the local host,\\\" because that lets me enforce some\\ngeneral organizational policy without having to care specifically\\nabout how each subscription is being set up.\\n\\nUnfortunately, I have even less of an idea about what the run-as\\nconcept is supposed to accomplish. I mean, at one level, I see it\\nquite clearly: the user creating the subscription wants replication to\\nhave restricted privileges when it's running, and so they make the\\nrun-as user some role with fewer privileges than their own. Brilliant.\\nBut then I get stuck: against what kind of attack does that actually\\nprotect us? If I'm a high privilege user, perhaps even a superuser,\\nand it's not safe to have logical replication running as me, then it\\nseems like the security model of logical replication is fundamentally\\nbusted and we need to fix that. It can't be right to say that if you\\nhave 263 users in a database and you want to replicate the whole\\ndatabase to some other node, you need 263 different subscriptions with\\na different run-as user for each. You need to be able to run all of\\nthat logical replication as the superuser or some other high-privilege\\nuser and not end up with a security compromise. And if we suppose that\\nthat already works and is safe, well then what's the case where I do\\nneed a run-as user?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 10:44:29 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 30, 2023, at 7:44 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> And if we suppose that\\n> that already works and is safe, well then what's the case where I do\\n> need a run-as user?\\n\\nA) Alice publishes tables, and occasionally adds new tables to existing publications.\\n\\nB) Bob manages subscriptions, and periodically runs \\\"refresh publication\\\". Bob also creates new subscriptions for people when a row is inserted into the \\\"please create a subscription for me\\\" table which Bob owns, using a trigger that Bob created on that table.\\n\\nC) Alice creates a \\\"please create a subscription for me\\\" table on the publishing database, adds lots of malicious requests, and adds that table to the publication.\\n\\nD) Bob replicates the table, fires the trigger, creates the malicious subscriptions, and starts replicating all that stuff, too.\\n\\nI think that having Charlie, not Bob, as the \\\"run-as\\\" user helps somewhere right around (D). \\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 08:11:03 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 30, 2023 at 11:11 AM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> > On Jan 30, 2023, at 7:44 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> >\\n> > And if we suppose that\\n> > that already works and is safe, well then what's the case where I do\\n> > need a run-as user?\\n>\\n> A) Alice publishes tables, and occasionally adds new tables to existing publications.\\n>\\n> B) Bob manages subscriptions, and periodically runs \\\"refresh publication\\\". Bob also creates new subscriptions for people when a row is inserted into the \\\"please create a subscription for me\\\" table which Bob owns, using a trigger that Bob created on that table.\\n>\\n> C) Alice creates a \\\"please create a subscription for me\\\" table on the publishing database, adds lots of malicious requests, and adds that table to the publication.\\n>\\n> D) Bob replicates the table, fires the trigger, creates the malicious subscriptions, and starts replicating all that stuff, too.\\n>\\n> I think that having Charlie, not Bob, as the \\\"run-as\\\" user helps somewhere right around (D).\\n\\nI suppose it does, but I have some complaints.\\n\\nFirst, it doesn't seem to make a lot of sense to have one person\\nmanaging the publications and someone else managing the subscriptions,\\nand especially if those parties are mutually untrusting. I can't think\\nof any real reason to set things up that way. Sure, you could, but why\\nwould you? You could, equally, decide that one member of your\\nhousehold was going to decide what's for dinner every night, and some\\nother member of your household was going to decide what gets purchased\\nat the grocery store each week. If those two people exercise their\\nresponsibilities without tight coordination, or with hostile intent\\ntoward each other, things are going to go badly, but that's not an\\nargument for putting a combination lock on the flour canister. It's an\\nargument for getting along better, or not having such a dumb system in\\nthe first place. I don't quite see how the situation you postulate in\\n(A) and (B) is any different. Publications and subscriptions are as\\nclosely connected as food purchases and meals. The point of a\\npublication is for it to connect up to a subscription. In what\\ncircumstances would be it be reasonable to give responsibility for\\nthose objects to different and especially mutually untrusting users?\\n\\nSecond, in step (B), we may ask why Bob is doing this with a trigger.\\nIf he's willing to create any subscription for which Alice asks, we\\ncould have just given Alice the authority to do those actions herself.\\nPresumably, therefore, Bob is willing to create some subscriptions for\\nwhich Alice may ask and not others. Perhaps this whole arrangement is\\njust a workaround for the lack of a sensible system for controlling\\nwhich connection strings Alice can use, in which case what is really\\nneeded here might be something like the separate connection object\\nwhich Jeff postulated or my idea of a reverse pg_hba.conf. That kind\\nof approach would give a better user interface to Alice, who wouldn't\\nhave to rephrase all of her CREATE SUBSCRIPTION commands as insert\\nstatements. Conversely, if Alice and Bob are truly dedicated to this\\nconvoluted system of creating subscriptions, then Bob needs to put\\nlogic into his trigger that's smart enough to block any malicious\\nrequests that Alice may make. He really brought this problem on\\nhimself by not doing that.\\n\\nThird, in step (C), it seems to me that whoever set up Alice's\\npermissions has really messed up. Either the schema Bob is using for\\nhis create-me-a-subscription table exists on the primary and Alice has\\npermission to create tables in that schema, or else that schema does\\nnot exist on the primary and Alice has permission to create it. Either\\nway, that's a bad setup. Bob's table should be located in a schema for\\nwhich Alice has only USAGE permissions and shouldn't have excess\\npermissions on the table, either. Then this step can't happen. This\\nstep could also be blocked if, instead of using a table with a\\ntrigger, Bob wrote a security definer function or procedure and\\ngranted EXECUTE permission on that function or procedure to Alice.\\nHe's still going to need sanity checks, though, and if the function or\\nprocedure inserts into a logging table or something, he'd better make\\nsure that table is adequately secured rather than being, say, a table\\nowned by Alice with malicious triggers on it.\\n\\nSo basically this doesn't really feel like a valid scenario to me.\\nWe're supposed to believe that Alice is hostile to Bob, but the\\nsuperuser doesn't seem to have thought very carefully about how Bob is\\nsupposed to defend himself against Alice, and Bob doesn't even seem to\\nbe trying. Maybe we should rename the users to Samson and Delilah? :-)\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 12:26:31 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 30, 2023, at 9:26 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> First, it doesn't seem to make a lot of sense to have one person\\n> managing the publications and someone else managing the subscriptions,\\n> and especially if those parties are mutually untrusting. I can't think\\n> of any real reason to set things up that way. Sure, you could, but why\\n> would you? You could, equally, decide that one member of your\\n> household was going to decide what's for dinner every night, and some\\n> other member of your household was going to decide what gets purchased\\n> at the grocery store each week. If those two people exercise their\\n> responsibilities without tight coordination, or with hostile intent\\n> toward each other, things are going to go badly, but that's not an\\n> argument for putting a combination lock on the flour canister. It's an\\n> argument for getting along better, or not having such a dumb system in\\n> the first place. I don't quite see how the situation you postulate in\\n> (A) and (B) is any different. Publications and subscriptions are as\\n> closely connected as food purchases and meals. The point of a\\n> publication is for it to connect up to a subscription.\\n\\nI have a grim view of the requirement that publishers and subscribers trust each other. Even when they do trust each other, they can firewall attacks by acting as if they do not.\\n\\n> In what\\n> circumstances would be it be reasonable to give responsibility for\\n> those objects to different and especially mutually untrusting users?\\n\\nWhen public repositories of data, such as the IANA whois database, publish their data via postgres publications.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 10:46:07 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 30, 2023, at 9:26 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> So basically this doesn't really feel like a valid scenario to me.\\n> We're supposed to believe that Alice is hostile to Bob, but the\\n> superuser doesn't seem to have thought very carefully about how Bob is\\n> supposed to defend himself against Alice, and Bob doesn't even seem to\\n> be trying. Maybe we should rename the users to Samson and Delilah? :-)\\n\\nNo, Atahualpa and Pizarro.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 11:09:26 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 30, 2023 at 1:46 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> I have a grim view of the requirement that publishers and subscribers trust each other. Even when they do trust each other, they can firewall attacks by acting as if they do not.\\n\\nI think it's OK if the CREATE PUBLICATION user doesn't particularly\\ntrust the CREATE SUBSCRIPTION user, because the publication is just a\\ngrouping of tables to which somebody can pay attention or not. The\\nCREATE PUBLICATION user isn't compromised either way. But, at least as\\nthings stand, I don't see how the CREATE SUBSCRIPTION user get away\\nwith not trusting the CREATE PUBLICATION user. CREATE SUBSCRIPTION\\nprovides no tools at all for filtering the data that the subscriber\\nchooses to send.\\n\\nNow that can be changed, I suppose, and a run-as user would be one way\\nto make progress in that direction. But I'm not sure how viable that\\nis, because...\\n\\n> > In what\\n> > circumstances would be it be reasonable to give responsibility for\\n> > those objects to different and especially mutually untrusting users?\\n>\\n> When public repositories of data, such as the IANA whois database, publish their data via postgres publications.\\n\\n... for that to work, IANA would need to set up the database so that\\nuntrusted parties can create logical replication slots on their\\nPostgreSQL server. And I think that granting REPLICATION privilege on\\nyour database to random people on the Internet is not really viable,\\nnor intended to be viable. As the CREATE ROLE documentation says, \\\"A\\nrole having the REPLICATION attribute is a very highly privileged\\nrole.\\\"\\n\\nConcretely, this kind of setup would have the problem that you could\\nkill the IANA database by just creating a replication slot and then\\nnot using it (or replicating from it only very very slowly).\\nEventually, the replication slot would either hold back xmin enough\\nthat you got a lot of bloat, or cause enough WAL to be retained that\\nyou ran out of disk space. Maybe you could protect yourself against\\nthat kind of problem by cutting off users who get too far behind, but\\nthat also cuts off people who just have an outage for longer than your\\ncutoff.\\n\\nAlso, anyone who can connection to a replication slot can also connect\\nto any other replication slot, and drop any replication slot. So if\\nIANA did grant REPLICATION privilege to random people on the Internet,\\none of them could jump into the system and screw things up for all the\\nothers.\\n\\nThis kind of setup just doesn't seem viable to me.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 14:30:27 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 30, 2023, at 11:30 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> CREATE SUBSCRIPTION\\n> provides no tools at all for filtering the data that the subscriber\\n> chooses to send.\\n> \\n> Now that can be changed, I suppose, and a run-as user would be one way\\n> to make progress in that direction. But I'm not sure how viable that\\n> is, because...\\n> \\n>>> In what\\n>>> circumstances would be it be reasonable to give responsibility for\\n>>> those objects to different and especially mutually untrusting users?\\n>> \\n>> When public repositories of data, such as the IANA whois database, publish their data via postgres publications.\\n> \\n> ... for that to work, IANA would need to set up the database so that\\n> untrusted parties can create logical replication slots on their\\n> PostgreSQL server. And I think that granting REPLICATION privilege on\\n> your database to random people on the Internet is not really viable,\\n> nor intended to be viable.\\n\\nThat was an aspirational example in which there's infinite daylight between the publisher and subscriber. I, too, doubt that's ever going to be possible. But I still think we should aspire to some extra daylight between the two. Perhaps IANA doesn't publish to the whole world, but instead publishes only to subscribers who have a contract in place, and have agreed to monetary penalties should they abuse the publishing server. Whatever. There's going to be some amount of daylight possible if we design for it, and none otherwise.\\n\\nMy real argument here isn't against your goal of having non-superusers who can create subscriptions. That part seems fine to me.\\n\\nGiven that my work last year made it possible for subscriptions to run as somebody other than the subscription creator, it annoys me that you now want the subscription creator's privileges to be what the subscription runs as. That seems to undo what I worked on. In my mental model of a (superuser-creator, non-superuser-owner) pair, it seems you're logically only touching the lefthand side, so you should then have a (nonsuperuser-creator, nonsuperuser-owner) pair. But you don't. You go the apparently needless extra step of just squashing them together. I just don't see why it needs to be like that.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 12:27:02 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 27, 2023 at 5:00 PM Andres Freund <andres@anarazel.de> wrote:\\n> > Or, another thought, maybe this should be checking for CREATE on the\\n> > current database + also pg_create_subscription. That seems like it\\n> > might be the right idea, actually.\\n>\\n> Yes, that seems like a good idea.\\n\\nDone in this version. I also changed check_conninfo to take an extra\\nargument instead of returning a Boolean, as per your suggestion.\\n\\nI had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\\nTO in terms of permissions checks. The previous version required that\\nthe new owner have permissions of pg_create_subscription, but there\\nseems to be no particular reason for that rule except that it happens\\nto be what I made the code do. So I changed it to say that the current\\nowner must have CREATE privilege on the database, and must be able to\\nSET ROLE to the new owner. This matches the rule for CREATE SCHEMA.\\nPossibly we should *additionally* require that the person performing\\nthe rename still have pg_create_subscription, but that shouldn't be\\nthe only requirement. This change means that you can't just randomly\\ngive your subscription to the superuser (with or without concurrently\\nattempting some other change as per your other comments) which is good\\nbecause you can't do that with other object types either.\\n\\nThere seems to be a good deal of inconsistency here. If you want to\\ngive someone a schema, YOU need CREATE on the database. But if you\\nwant to give someone a table, THEY need CREATE on the containing\\nschema. It make sense that we check permissions on the containing\\nobject, which could be a database or a schema depending on what you're\\nrenaming, but it's unclear to me why we sometimes check on the person\\nperforming the ALTER command and at other times on the recipient. It's\\nalso somewhat unclear to me why we are checking CREATE in the first\\nplace, especially on the donor. It might make sense to have a rule\\nthat you can't own an object in a place where you couldn't have\\ncreated it, but there is no such rule, because you can give someone\\nCREATE on a schema, they can create an object, and they you can take\\nCREATE a way and they still own an object there. So it kind of looks\\nto me like we made it up as we went along and that the result isn't\\nvery consistent, but I'm inclined to follow CREATE SCHEMA here unless\\nthere's some reason to do otherwise.\\n\\nAnother question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\\nSUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\\nsuperuser and password_required false is set. They are separate code\\npaths from the rest of the ALTER SUBSCRIPTION cases, so if we want\\nthat to be a rule we need dedicated code for it. I'm not quite sure\\nwhat's right. There's no comparable case for ALTER USER MAPPING\\nbecause a user mapping doesn't have an owner and so can't be\\nreassigned to a new owner. I don't see what the harm is, especially\\nfor RENAME, but I might be missing something, and it certainly seems\\narguable.\\n\\n> > I'm not entirely clear whether there's a hazard there.\\n>\\n> I'm not at all either. It's just a code pattern that makes me anxious - I\\n> suspect there's a few places it makes us more vulnerable.\\n\\nIt looks likely to me that it was cut down from the CREATE SCHEMA code, FWIW.\\n\\n> > If there is, I think we could fix it by moving the LockSharedObject call up\\n> > higher, above object_ownercheck. The only problem with that is it lets you\\n> > lock an object on which you have no permissions: see\\n> > 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\\n> > analogue of RangeVarGetRelidExtended.\\n>\\n> Yea, we really should have something like RangeVarGetRelidExtended() for other\\n> kinds of objects. It'd take a fair bit of work / time to use it widely, but\\n> it'll take even longer if we start in 5 years ;)\\n\\nWe actually have something sort of like that in the form of\\nget_object_address(). It doesn't allow for a callback, but it does\\nhave a retry loop.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 30 Jan 2023 15:32:34 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 27, 2023 at 1:08 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > 1) Forwarding the original ambient context along with the request, so\\n> > the server can check it too.\\n>\\n> Right, so a protocol extension. Reasonable idea, but a big lift. Not\\n> only do you need everyone to be running a new enough version of\\n> PostgreSQL, but existing proxies like pgpool and pgbouncer need\\n> updates, too.\\n\\nRight.\\n\\n> > 2) Explicitly combining the request with the proof of authority needed\\n> > to make it, as in capability-based security [3].\\n>\\n> As far as I can see, that link doesn't address how you'd make this\\n> approach work across a network.\\n\\nThe CSRF-token example I gave is one. But that's HTTP-specific\\n(stateless, server-driven) and probably doesn't make a lot of sense\\nfor our case.\\n\\nFor our case, assuming that connections have side effects, one\\nsolution could be for the client to signal to the server that the\\nconnection should use in-band authentication only; i.e. fail the\\nconnection if the credentials provided aren't good enough by\\nthemselves to authenticate the client. (This has some overlap with\\nSASL negotiation, maybe.)\\n\\nBut that still requires server support. I don't know if there's a\\nclever way to tie the authentication to the request on the client side\\nonly, using existing server implementations. (If connections don't\\nhave side effects, require_auth should be sufficient.)\\n\\n> > 3) Dropping as many implicitly-held privileges as possible before making\\n> > a request. This doesn't solve the problem but may considerably reduce\\n> > the practical attack surface.\\n>\\n> Right. I definitely don't object to this kind of approach, but I don't\\n> think it can ever be sufficient by itself.\\n\\nI agree. (But for the record, I think that an outbound proxy filter is\\nalso insufficient. Someone, somewhere, is going to want to safely\\nproxy through localhost _and_ have peer authentication set up.)\\n\\n> > I think this style focuses on absolute configuration flexibility at the\\n> > expense of usability. It obfuscates the common use cases. (I have the\\n> > exact same complaint about our HBA and ident configs, so I may be\\n> > fighting uphill.)\\n>\\n> That's probably somewhat true, but on the other hand, it also is more\\n> powerful than what you're describing. In your system, is there some\\n> way the DBA can say \\\"hey, you can connect to any of the machines on\\n> this list of subnets, but nothing else\\\"? Or equally, \\\"hey, you may NOT\\n> connect to any machine on this list of subnets, but anything else is\\n> fine\\\"? Or \\\"you can connect to these subnets without SSL, but if you\\n> want to talk to anything else, you need to use SSL\\\"?\\n\\nI guess I didn't call it out explicitly, so it was fair to assume that\\nit did not. I don't think we should ignore those cases.\\n\\nBut if we let the configuration focus on policies instead, and\\nsimultaneously improve the confused-deputy problem, then any IP/host\\nfilter functionality that we provide becomes an additional safety\\nmeasure instead of your only viable line of defense. \\\"I screwed up our\\nIP filter, but we're still safe because the proxy refused to forward\\nits client cert to the backend.\\\" Or, \\\"this other local application\\nrequires peer authentication, but it's okay because the proxy\\ndisallows those connections by default.\\\"\\n\\n> Your idea\\n> seems to rely on us being able to identify all of the policies that a\\n> user is likely to want and give names to each one, and I don't feel\\n> very confident that that's realistic. But maybe I'm misinterpreting\\n> your idea?\\n\\nNo, that's pretty accurate. But I'm used to systems that provide a\\nridiculous number of policies [1, 2] via what's basically a scoped\\nproperty bag. \\\"Turn off option 1 and 2 globally. For host A and IP\\naddress B, turn on option 1 as an exception.\\\" And I don't really\\nexpect us to need as many options as those systems do.\\n\\nI think that configuration style evolves well, it focuses on the right\\nthings, and it can still handle IP lists intuitively [3], if that's\\nthe way a DBA really wants to set up policies.\\n\\n--Jacob\\n\\n[1] https://httpd.apache.org/docs/2.4/mod/mod_proxy.html\\n[2] https://www.haproxy.com/documentation/hapee/latest/onepage/#4\\n[3] https://docs.nginx.com/nginx/admin-guide/security-controls/controlling-access-proxied-tcp/\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 13:12:31 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 30, 2023 at 3:27 PM Mark Dilger\\n<mark.dilger@enterprisedb.com> wrote:\\n> That was an aspirational example in which there's infinite daylight between the publisher and subscriber. I, too, doubt that's ever going to be possible. But I still think we should aspire to some extra daylight between the two. Perhaps IANA doesn't publish to the whole world, but instead publishes only to subscribers who have a contract in place, and have agreed to monetary penalties should they abuse the publishing server. Whatever. There's going to be some amount of daylight possible if we design for it, and none otherwise.\\n>\\n> My real argument here isn't against your goal of having non-superusers who can create subscriptions. That part seems fine to me.\\n>\\n> Given that my work last year made it possible for subscriptions to run as somebody other than the subscription creator, it annoys me that you now want the subscription creator's privileges to be what the subscription runs as. That seems to undo what I worked on. In my mental model of a (superuser-creator, non-superuser-owner) pair, it seems you're logically only touching the lefthand side, so you should then have a (nonsuperuser-creator, nonsuperuser-owner) pair. But you don't. You go the apparently needless extra step of just squashing them together. I just don't see why it needs to be like that.\\n\\nI feel like you're accusing me of removing functionality that has\\nnever existed. A subscription doesn't run as the subscription creator.\\nIt runs as the subscription owner. If you or anyone else had added the\\ncapability for it to run as someone other than the subscription owner,\\nI certainly wouldn't be trying to back that capability out as part of\\nthis patch, and because there isn't, I'm not proposing to add that as\\npart of this patch. I don't see how that makes me guilty of squashing\\nanything together. The current state of affairs, where the run-as user\\nis taken from pg_subscription.subowner, the same field that is updated\\nby ALTER SUBSCRIPTION ... OWNER TO, is the result of your work, not\\nanything that I have done or am proposing to do.\\n\\nI also *emphatically* disagree with the idea that this undoes what you\\nworked on. My patch would be *impossible* without your work. Prior to\\nyour work, the run-as user was always, basically, the superuser, and\\nso the idea of allowing anyone other than a superuser to execute\\nCREATE SUBSCRIPTION would be flat-out nuts. Because of your work,\\nthat's now a thing that we may be able to reasonably allow, if we can\\nwork through the remaining issues. So I'm grateful to you, and also\\nsorry to hear that you're annoyed with me. But I still don't think\\nthat the fact that the division you want doesn't exist is somehow my\\nfault.\\n\\nI'm kind of curious why you *didn't* make this distinction at the time\\nthat you were did the other work in this area. Maybe my memory is\\nplaying tricks on me again, but I seem to recall talking about the\\nidea with you at the time, and I seem to recall thinking that it\\nsounded like an OK idea. I seem to vaguely recall us discussing\\nhazards like: well, what if replication causes code to get executed as\\nthe subscription owner that that causes something bad to happen? But I\\nthink the only way that happens is if they put triggers on the tables\\nthat are being replicated, which is their choice, and they can avoid\\ninstalling problematic code there if they want. I think there might\\nhave been some other scenarios, too, but I just can't remember. In any\\ncase, I don't think the idea is completely without merit. I think it\\ncould very well be something that we want to have for one reason or\\nanother. But I don't currently understand exactly what those reasons\\nare, and I don't see any reason why one patch should both split owner\\nfrom run-as user and also allow the owner to be a non-superuser. That\\nseems like two different efforts to me.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 16:29:06 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 30, 2023 at 4:12 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> For our case, assuming that connections have side effects, one\\n> solution could be for the client to signal to the server that the\\n> connection should use in-band authentication only; i.e. fail the\\n> connection if the credentials provided aren't good enough by\\n> themselves to authenticate the client. (This has some overlap with\\n> SASL negotiation, maybe.)\\n\\nI'm not an expert on this stuff, but to me that feels like a weak and\\nfuzzy concept. If the client is going to tell the server something,\\nI'd much rather have it say something like \\\"i'm proxying a request\\nfrom my local user rhaas, who authenticated using such and such a\\nmethod and connected from such and such an IP yadda yadda\\\". That feels\\nto me like really clear communication that the server can then be\\nconfigured to something about via pg_hba.conf or similar. Saying \\\"use\\nin-band authentication only\\\", to me, feels much murkier. As the\\nrecipient of that message, I don't know exactly what to do about it,\\nand it feels like whatever heuristic I adopt might end up being wrong\\nand something bad happens anyway.\\n\\n> I agree. (But for the record, I think that an outbound proxy filter is\\n> also insufficient. Someone, somewhere, is going to want to safely\\n> proxy through localhost _and_ have peer authentication set up.)\\n\\nWell then they're indeed going to need some way to distinguish a\\nproxied connection from a non-proxied one. You can't send identical\\nconnection requests in different scenarios and get different\\nresults....\\n\\n> I guess I didn't call it out explicitly, so it was fair to assume that\\n> it did not. I don't think we should ignore those cases.\\n\\nOK, cool.\\n\\n> But if we let the configuration focus on policies instead, and\\n> simultaneously improve the confused-deputy problem, then any IP/host\\n> filter functionality that we provide becomes an additional safety\\n> measure instead of your only viable line of defense. \\\"I screwed up our\\n> IP filter, but we're still safe because the proxy refused to forward\\n> its client cert to the backend.\\\" Or, \\\"this other local application\\n> requires peer authentication, but it's okay because the proxy\\n> disallows those connections by default.\\\"\\n\\nDefense in depth is good.\\n\\n> > Your idea\\n> > seems to rely on us being able to identify all of the policies that a\\n> > user is likely to want and give names to each one, and I don't feel\\n> > very confident that that's realistic. But maybe I'm misinterpreting\\n> > your idea?\\n>\\n> No, that's pretty accurate. But I'm used to systems that provide a\\n> ridiculous number of policies [1, 2] via what's basically a scoped\\n> property bag. \\\"Turn off option 1 and 2 globally. For host A and IP\\n> address B, turn on option 1 as an exception.\\\" And I don't really\\n> expect us to need as many options as those systems do.\\n>\\n> I think that configuration style evolves well, it focuses on the right\\n> things, and it can still handle IP lists intuitively [3], if that's\\n> the way a DBA really wants to set up policies.\\n\\nI think what we really need here is an example or three of a proposed\\nconfiguration file syntax. I think it would be good if we could pick a\\nsyntax that doesn't require a super-complicated parser, and that maybe\\nhas something in common with our existing configuration file syntaxes.\\nBut if we have to invent something new, then we can do that.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 30 Jan 2023 17:21:22 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Jan 30, 2023, at 1:29 PM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> I feel like you're accusing me of removing functionality that has\\n> never existed. A subscription doesn't run as the subscription creator.\\n> It runs as the subscription owner. If you or anyone else had added the\\n> capability for it to run as someone other than the subscription owner,\\n> I certainly wouldn't be trying to back that capability out as part of\\n> this patch, and because there isn't, I'm not proposing to add that as\\n> part of this patch. I don't see how that makes me guilty of squashing\\n> anything together. The current state of affairs, where the run-as user\\n> is taken from pg_subscription.subowner, the same field that is updated\\n> by ALTER SUBSCRIPTION ... OWNER TO, is the result of your work, not\\n> anything that I have done or am proposing to do.\\n> \\n> I also *emphatically* disagree with the idea that this undoes what you\\n> worked on. My patch would be *impossible* without your work. Prior to\\n> your work, the run-as user was always, basically, the superuser, and\\n> so the idea of allowing anyone other than a superuser to execute\\n> CREATE SUBSCRIPTION would be flat-out nuts. Because of your work,\\n> that's now a thing that we may be able to reasonably allow, if we can\\n> work through the remaining issues. So I'm grateful to you, and also\\n> sorry to hear that you're annoyed with me. But I still don't think\\n> that the fact that the division you want doesn't exist is somehow my\\n> fault.\\n> \\n> I'm kind of curious why you *didn't* make this distinction at the time\\n> that you were did the other work in this area. Maybe my memory is\\n> playing tricks on me again, but I seem to recall talking about the\\n> idea with you at the time, and I seem to recall thinking that it\\n> sounded like an OK idea. I seem to vaguely recall us discussing\\n> hazards like: well, what if replication causes code to get executed as\\n> the subscription owner that that causes something bad to happen? But I\\n> think the only way that happens is if they put triggers on the tables\\n> that are being replicated, which is their choice, and they can avoid\\n> installing problematic code there if they want. I think there might\\n> have been some other scenarios, too, but I just can't remember. In any\\n> case, I don't think the idea is completely without merit. I think it\\n> could very well be something that we want to have for one reason or\\n> another. But I don't currently understand exactly what those reasons\\n> are, and I don't see any reason why one patch should both split owner\\n> from run-as user and also allow the owner to be a non-superuser. That\\n> seems like two different efforts to me.\\n\\nI don't have a concrete problem with your patch, and wouldn't object if you committed it. My concerns were more how you were phrasing things, but it seems not worth any additional conversation, because it's probably a distinction without a difference.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 31 Jan 2023 03:32:38 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-30 10:44:29 -0500, Robert Haas wrote:\\n> On a technical level, I think that the idea of having a separate\\n> objection for the connection string vs. the subscription itself is\\n> perfectly sound, and to repeat what I said earlier, if someone wants\\n> to implement that, cool. I also agree that it has the advantage that\\n> you specify, namely, that someone can have rights to modify one of\\n> those objects but not the other. What that lets you do is define a\\n> short list of known systems and say, hey, you can replicate whatever\\n> tables you want with whatever options you want, but only between these\\n> systems. I'm not quite sure what problem that solves, though.\\n\\nThat does seem somewhat useful, but also fairly limited, at least as\\nlong as it's really just a single connection, rather than a \\\"pattern\\\" of\\nsafe connections.\\n\\n\\n> Unfortunately, I have even less of an idea about what the run-as\\n> concept is supposed to accomplish. I mean, at one level, I see it\\n> quite clearly: the user creating the subscription wants replication to\\n> have restricted privileges when it's running, and so they make the\\n> run-as user some role with fewer privileges than their own. Brilliant.\\n> But then I get stuck: against what kind of attack does that actually\\n> protect us? If I'm a high privilege user, perhaps even a superuser,\\n> and it's not safe to have logical replication running as me, then it\\n> seems like the security model of logical replication is fundamentally\\n> busted and we need to fix that.\\n\\nI don't really understand that - the run-as approach seems like a\\nnecessary piece of improving the security model.\\n\\nI think it's perfectly reasonable to want to replicate from one system\\nin another, but to not want to allow logical replication to insert into\\npg_class or whatnot. So not using superuser to execute the replication\\nmakes sense.\\n\\nThis is particularly the case if you're just replicating a small part of\\nthe tables from one system to another. E.g. in a sharded setup, you may\\nwant to replicate metadata too servers.\\n\\nEven if all the systems are operated by people you trust (including\\npossibly even yourself, if you want to go that far), you may want to\\nreduce the blast radius of privilege escalation, or even just bugs, to a\\nsmaller amount of data.\\n\\n\\nI think we'll need two things to improve upon the current situation:\\n\\n1) run-as user, to reduce the scope of potential danger\\n\\n2) Option to run the database inserts as the owner of the table, with a\\n check that the run-as is actually allowed to perform work as the\\n owning role. That prevents escalation from table owner (who could add\\n default expressions etc) from gettng the privs of the\\n run-as/replication owner.\\n\\n\\nI think it makes sense for 1) to be a fairly privileged user, but I\\nthink it's good practice for that user to not be allowed to change the\\nsystem configuration etc.\\n\\n\\n> It can't be right to say that if you have 263 users in a database and\\n> you want to replicate the whole database to some other node, you need\\n> 263 different subscriptions with a different run-as user for each. You\\n> need to be able to run all of that logical replication as the\\n> superuser or some other high-privilege user and not end up with a\\n> security compromise.\\n\\nI'm not quite following along here - are you thinking of 263 tables\\nowned by 263 users? If yes, that's why I am thinking that we need the\\noption to perform each table modification as the owner of that table\\n(with the same security restrictions we use for REINDEX etc).\\n\\n\\n> And if we suppose that that already works and is safe, well then\\n> what's the case where I do need a run-as user?\\n\\nIt's not at all safe today, IMO. You need to trust that nothing bad will\\nbe replicated, otherwise the owner of the subscription has to be\\nconsidered compromised.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 31 Jan 2023 16:01:16 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 31, 2023 at 7:01 PM Andres Freund <andres@anarazel.de> wrote:\\n> I don't really understand that - the run-as approach seems like a\\n> necessary piece of improving the security model.\\n>\\n> I think it's perfectly reasonable to want to replicate from one system\\n> in another, but to not want to allow logical replication to insert into\\n> pg_class or whatnot. So not using superuser to execute the replication\\n> makes sense.\\n>\\n> This is particularly the case if you're just replicating a small part of\\n> the tables from one system to another. E.g. in a sharded setup, you may\\n> want to replicate metadata too servers.\\n\\nI don't think that a system catalog should be considered a valid\\nreplication target, no matter who owns the subscription, so ISTM that\\nwriting to pg_class should be blocked regardless. The thing I'm\\nstruggling to understand is: if you only want to replicate into tables\\nthat Alice can write, why not just make Alice own the subscription?\\nFor a run-as user to make sense, you need a scenario where we want the\\nreplication to target only tables that Alice can touch, but we also\\ndon't want Alice herself to be able to touch the subscription, so you\\nmake Alice the run-as user and yourself the owner, or something like\\nthat. But I'm not sure what that scenario is exactly.\\n\\nMark was postulating a scenario where the publisher and subscriber\\ndon't trust each other. I was thinking a little bit more about that. I\\nstill maintain that the current system is poorly set up to make that\\nwork, but suppose we wanted to do better. We could add filtering on\\nthe subscriber side, like you list schemas or specific relations that\\nyou are or are not willing to replicate into. Then you could, for\\nexample, connect your subscription to a certain remote publication,\\nbut with the restriction that you're only willing to replicate into\\nthe \\\"headquarters\\\" schema. Then we'll replicate whatever tables they\\nsend us, but if the dorks at headquarters mess up the publications on\\ntheir end (intentionally or otherwise) and add some tables from the\\n\\\"locally_controlled_stuff\\\" schema, we'll refuse to replicate that into\\nour eponymous schema. I don't think this kind of system is well-suited\\nto environments where people are totally hostile to each other,\\nbecause you still need to have replication slots on the remote side\\nand stuff. Also, having the remote side decode stuff and ignoring it\\nlocally is expensive, and I bet if we add stuff like this then people\\nwill misuse it and be sad. But it would make the system easier to\\nreason about: I know for sure that this subscription will only write\\nto these places, because that's all I've given it permission to do.\\n\\nIn the sharding scenario you mention, if you want to provide\\naccidental writes to unrelated tables due to the publication being not\\nwhat we expect, you can either make the subscription owned by the same\\nrole that owns the sharded tables, or a special-purpose role that has\\npermission to write to exactly the set of tables that you expect to be\\ntouched and no others. Or, if you had something like what I posited in\\nthe last paragraph, you could use that instead. But I don't see how a\\nseparate run-as user helps. If I'm just being super-dense here, I hope\\nthat one of you will explain using short words. :-)\\n\\n> I think we'll need two things to improve upon the current situation:\\n>\\n> 1) run-as user, to reduce the scope of potential danger\\n>\\n> 2) Option to run the database inserts as the owner of the table, with a\\n> check that the run-as is actually allowed to perform work as the\\n> owning role. That prevents escalation from table owner (who could add\\n> default expressions etc) from gettng the privs of the\\n> run-as/replication owner.\\n\\nI'm not quite sure what we do here now, but I agree that trigger\\nfiring seems like a problem. It might be that we need to worry about\\nthe user on the origin server, too. If Alice inserts a row that causes\\na replicated table owned by Bob to fire a trigger or evaluate a\\ndefault expression or whatever due the presence of a subscription\\nowned by Charlie, there is a risk that Alice might try to attack\\neither Bob or Charlie, or that Bob might try to attack Charlie.\\n\\n> > And if we suppose that that already works and is safe, well then\\n> > what's the case where I do need a run-as user?\\n>\\n> It's not at all safe today, IMO. You need to trust that nothing bad will\\n> be replicated, otherwise the owner of the subscription has to be\\n> considered compromised.\\n\\nWhat kinds of things are bad to replicate?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Feb 2023 09:43:39 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Feb 1, 2023, at 6:43 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n\\n> The thing I'm\\n> struggling to understand is: if you only want to replicate into tables\\n> that Alice can write, why not just make Alice own the subscription?\\n> For a run-as user to make sense, you need a scenario where we want the\\n> replication to target only tables that Alice can touch, but we also\\n> don't want Alice herself to be able to touch the subscription, so you\\n> make Alice the run-as user and yourself the owner, or something like\\n> that. But I'm not sure what that scenario is exactly.\\n\\nThis \\\"run-as\\\" idea came about because we didn't want arbitrary roles to be able to change the subscription's connection string. A competing idea was to have a server object rather than a string, with roles like Alice being able to use the server object if they have been granted usage privilege, and not otherwise. So the \\\"run-as\\\" and \\\"server\\\" ideas were somewhat competing.\\n\\n> Mark was postulating a scenario where the publisher and subscriber\\n> don't trust each other. I was thinking a little bit more about that. I\\n> still maintain that the current system is poorly set up to make that\\n> work, but suppose we wanted to do better. We could add filtering on\\n> the subscriber side, like you list schemas or specific relations that\\n> you are or are not willing to replicate into. Then you could, for\\n> example, connect your subscription to a certain remote publication,\\n> but with the restriction that you're only willing to replicate into\\n> the \\\"headquarters\\\" schema. Then we'll replicate whatever tables they\\n> send us, but if the dorks at headquarters mess up the publications on\\n> their end (intentionally or otherwise) and add some tables from the\\n> \\\"locally_controlled_stuff\\\" schema, we'll refuse to replicate that into\\n> our eponymous schema.\\n\\nThat example is good, though I don't see how \\\"filters\\\" are better than roles+privileges. Care to elaborate?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Feb 2023 09:22:31 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 30, 2023 at 2:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Mon, Jan 30, 2023 at 4:12 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > For our case, assuming that connections have side effects, one\\n> > solution could be for the client to signal to the server that the\\n> > connection should use in-band authentication only; i.e. fail the\\n> > connection if the credentials provided aren't good enough by\\n> > themselves to authenticate the client. (This has some overlap with\\n> > SASL negotiation, maybe.)\\n>\\n> I'm not an expert on this stuff, but to me that feels like a weak and\\n> fuzzy concept. If the client is going to tell the server something,\\n> I'd much rather have it say something like \\\"i'm proxying a request\\n> from my local user rhaas, who authenticated using such and such a\\n> method and connected from such and such an IP yadda yadda\\\". That feels\\n> to me like really clear communication that the server can then be\\n> configured to something about via pg_hba.conf or similar. Saying \\\"use\\n> in-band authentication only\\\", to me, feels much murkier. As the\\n> recipient of that message, I don't know exactly what to do about it,\\n> and it feels like whatever heuristic I adopt might end up being wrong\\n> and something bad happens anyway.\\n\\nIs it maybe just a matter of terminology? If a proxy tells the server,\\n\\\"This user is logging in. Here's the password I have for them. DO NOT\\nauthenticate using anything else,\\\" and the HBA says to use ident auth\\nfor that user, then the server fails the connection. That's what I\\nmean by in-band -- the proxy says, \\\"here are the credentials for this\\nconnection.\\\" That's it.\\n\\nAlternatively, if you really don't like making this server-side: any\\nfuture \\\"connection side effects\\\" we add, such as logon triggers, could\\neither be opted into by the client or explicitly invoked by the client\\nafter it's happy with the authentication exchange. Or it could be\\ndisabled at the server side for forms of ambient authn. (This is\\ngetting closer to HTTP's method safety concept.)\\n\\n> > I agree. (But for the record, I think that an outbound proxy filter is\\n> > also insufficient. Someone, somewhere, is going to want to safely\\n> > proxy through localhost _and_ have peer authentication set up.)\\n>\\n> Well then they're indeed going to need some way to distinguish a\\n> proxied connection from a non-proxied one. You can't send identical\\n> connection requests in different scenarios and get different\\n> results....\\n\\nYeah. Most of these solutions require explicitly labelling things that\\nwere implicit before.\\n\\n> I think what we really need here is an example or three of a proposed\\n> configuration file syntax. I think it would be good if we could pick a\\n> syntax that doesn't require a super-complicated parser\\n\\nAgreed. The danger from my end is, I'm trained on configuration\\nformats that have infinite bells and whistles. I don't really want to\\ngo too crazy with it.\\n\\n> and that maybe\\n> has something in common with our existing configuration file syntaxes.\\n> But if we have to invent something new, then we can do that.\\n\\nOkay. Personally I'd like\\n- the ability to set options globally (so filters are optional)\\n- the ability to maintain many options for a specific scope (host? IP\\nrange?) without making my config lines grow without bound\\n- the ability to audit a configuration without trusting its comments\\n\\nBut getting all of my wishlist into a sane configuration format that\\nhandles all the use cases is the tricky part. I'll think about it.\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Feb 2023 12:37:26 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-01 09:43:39 -0500, Robert Haas wrote:\\n> On Tue, Jan 31, 2023 at 7:01 PM Andres Freund <andres@anarazel.de> wrote:\\n> > I don't really understand that - the run-as approach seems like a\\n> > necessary piece of improving the security model.\\n> >\\n> > I think it's perfectly reasonable to want to replicate from one system\\n> > in another, but to not want to allow logical replication to insert into\\n> > pg_class or whatnot. So not using superuser to execute the replication\\n> > makes sense.\\n> >\\n> > This is particularly the case if you're just replicating a small part of\\n> > the tables from one system to another. E.g. in a sharded setup, you may\\n> > want to replicate metadata too servers.\\n> \\n> I don't think that a system catalog should be considered a valid\\n> replication target, no matter who owns the subscription, so ISTM that\\n> writing to pg_class should be blocked regardless.\\n\\nThe general point is that IMO is that in many setups you should use a\\nuser with fewer privileges than a superuser. It doesn't really matter\\nwhether we have an ad-hoc restriction for system catalogs. More often\\nthan not being able to modify other tables will give you a lot of\\nprivileges too.\\n\\n\\n> The thing I'm struggling to understand is: if you only want to\\n> replicate into tables that Alice can write, why not just make Alice\\n> own the subscription?\\n\\nBecause it implies that the replication happens as a user that's\\nprivileged enough to change the configuration of replication.\\n\\n\\n> Mark was postulating a scenario where the publisher and subscriber\\n> don't trust each other.\\n\\nFWIW, I don't this this is mainly about \\\"trust\\\", but instead about\\nlayering security / the principle of least privilege. The \\\"run-as\\\" user\\n(i.e. currently owner) is constantly performing work on behalf of a\\nremote node, including executing code (default clauses etc). To make it\\nharder to use such a cross-system connection to move from one system to\\nthe next, it's a good idea to execute it in the least privileged context\\npossible. And I don't see why it'd need the permission to modify the\\ndefinition of the subscription and similar \\\"admin\\\" tasks.\\n\\nIt's not that such an extra layer would necessarily completely stop an\\nattacker. But it might delay them and make their attack more noisy.\\n\\n\\nSimilarly, if I were to operate an important production environment\\nagain, I'd not have relations owned by the [pseudo]superuser, but by a\\nuser controlled by the [pseudo]superuser. That way somebody tricking the\\nsuperuser into a REINDEX or such only gets the ability to execute code\\nin a less privileged context.\\n\\n\\n\\n\\n> I was thinking a little bit more about that. I\\n> still maintain that the current system is poorly set up to make that\\n> work, but suppose we wanted to do better. We could add filtering on\\n> the subscriber side, like you list schemas or specific relations that\\n> you are or are not willing to replicate into.\\n\\nIsn't that largely a duplication of the ACLs on relations etc?\\n\\n\\n> > I think we'll need two things to improve upon the current situation:\\n> >\\n> > 1) run-as user, to reduce the scope of potential danger\\n> >\\n> > 2) Option to run the database inserts as the owner of the table, with a\\n> > check that the run-as is actually allowed to perform work as the\\n> > owning role. That prevents escalation from table owner (who could add\\n> > default expressions etc) from gettng the privs of the\\n> > run-as/replication owner.\\n> \\n> I'm not quite sure what we do here now, but I agree that trigger\\n> firing seems like a problem. It might be that we need to worry about\\n> the user on the origin server, too. If Alice inserts a row that causes\\n> a replicated table owned by Bob to fire a trigger or evaluate a\\n> default expression or whatever due the presence of a subscription\\n> owned by Charlie, there is a risk that Alice might try to attack\\n> either Bob or Charlie, or that Bob might try to attack Charlie.\\n\\nThe attack on Bob exists without logical replication too - a REINDEX or\\nsuch is executed as the owner of the relation and re-evaluates index\\nexpressions, constraints etc. Given our security model I don't think we\\ncan protect the relation owner if they trust somebody to insert rows, so\\nI don't really know what we can do to protect Charlie against Bob.\\n\\n\\n\\n> > > And if we suppose that that already works and is safe, well then\\n> > > what's the case where I do need a run-as user?\\n> >\\n> > It's not at all safe today, IMO. You need to trust that nothing bad will\\n> > be replicated, otherwise the owner of the subscription has to be\\n> > considered compromised.\\n> \\n> What kinds of things are bad to replicate?\\n\\nI think that's unfortunately going to be specific to a setup.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Feb 2023 12:37:28 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-01-30 15:32:34 -0500, Robert Haas wrote:\\n> I had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\\n> TO in terms of permissions checks. The previous version required that\\n> the new owner have permissions of pg_create_subscription, but there\\n> seems to be no particular reason for that rule except that it happens\\n> to be what I made the code do. So I changed it to say that the current\\n> owner must have CREATE privilege on the database, and must be able to\\n> SET ROLE to the new owner. This matches the rule for CREATE SCHEMA.\\n> Possibly we should *additionally* require that the person performing\\n> the rename still have pg_create_subscription, but that shouldn't be\\n> the only requirement.\\n\\nAs long as owner and run-as are the same, I think it's strongly\\npreferrable to *not* require pg_create_subscription.\\n\\n\\n> There seems to be a good deal of inconsistency here. If you want to\\n> give someone a schema, YOU need CREATE on the database. But if you\\n> want to give someone a table, THEY need CREATE on the containing\\n> schema. It make sense that we check permissions on the containing\\n> object, which could be a database or a schema depending on what you're\\n> renaming, but it's unclear to me why we sometimes check on the person\\n> performing the ALTER command and at other times on the recipient. It's\\n> also somewhat unclear to me why we are checking CREATE in the first\\n> place, especially on the donor. It might make sense to have a rule\\n> that you can't own an object in a place where you couldn't have\\n> created it, but there is no such rule, because you can give someone\\n> CREATE on a schema, they can create an object, and they you can take\\n> CREATE a way and they still own an object there. So it kind of looks\\n> to me like we made it up as we went along and that the result isn't\\n> very consistent, but I'm inclined to follow CREATE SCHEMA here unless\\n> there's some reason to do otherwise.\\n\\nYuck. No idea what the best policy around this is.\\n\\n\\n> Another question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\\n> SUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\\n> superuser and password_required false is set.\\n\\nI don't really see a benefit in allowing it, so I'm inclined to go for\\nthe more restrictive option. But this is a really weakly held opinion.\\n\\n\\n\\n> > > If there is, I think we could fix it by moving the LockSharedObject call up\\n> > > higher, above object_ownercheck. The only problem with that is it lets you\\n> > > lock an object on which you have no permissions: see\\n> > > 2ad36c4e44c8b513f6155656e1b7a8d26715bb94. To really fix that, we'd need an\\n> > > analogue of RangeVarGetRelidExtended.\\n> >\\n> > Yea, we really should have something like RangeVarGetRelidExtended() for other\\n> > kinds of objects. It'd take a fair bit of work / time to use it widely, but\\n> > it'll take even longer if we start in 5 years ;)\\n>\\n> We actually have something sort of like that in the form of\\n> get_object_address(). It doesn't allow for a callback, but it does\\n> have a retry loop.\\n\\nHm, sure looks like that code doesn't do any privilege checking...\\n\\n\\n> @@ -1269,13 +1270,19 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)\\n> \\t\\t\\t\\t\\t\\t\\t\\t\\tslotname,\\n> \\t\\t\\t\\t\\t\\t\\t\\t\\tNAMEDATALEN);\\n>\\n> +\\t/* Is the use of a password mandatory? */\\n> +\\tmust_use_password = MySubscription->passwordrequired &&\\n> +\\t\\t!superuser_arg(MySubscription->owner);\\n\\nThere's a few repetitions of this - perhaps worth putting into a helper?\\n\\n\\n> @@ -180,6 +181,13 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,\\n> if (PQstatus(conn->streamConn) != CONNECTION_OK)\\n> goto bad_connection_errmsg;\\n>\\n> + if (must_use_password && !PQconnectionUsedPassword(conn->streamConn))\\n> + ereport(ERROR,\\n> + (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),\\n> + errmsg(\\\"password is required\\\"),\\n> + errdetail(\\\"Non-superuser cannot connect if the server does not request a password.\\\"),\\n> + errhint(\\\"Target server's authentication method must be changed. or set password_required=false in the subscription attributes\\\\\\n.\\\")));\\n> +\\n> if (logical)\\n> {\\n> PGresult *res;\\n\\nThis still leaks the connection on error, no?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Feb 2023 13:02:29 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 1, 2023 at 1:09 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:\\n> > On Feb 1, 2023, at 6:43 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> > The thing I'm\\n> > struggling to understand is: if you only want to replicate into tables\\n> > that Alice can write, why not just make Alice own the subscription?\\n> > For a run-as user to make sense, you need a scenario where we want the\\n> > replication to target only tables that Alice can touch, but we also\\n> > don't want Alice herself to be able to touch the subscription, so you\\n> > make Alice the run-as user and yourself the owner, or something like\\n> > that. But I'm not sure what that scenario is exactly.\\n>\\n> This \\\"run-as\\\" idea came about because we didn't want arbitrary roles to be able to change the subscription's connection string. A competing idea was to have a server object rather than a string, with roles like Alice being able to use the server object if they have been granted usage privilege, and not otherwise. So the \\\"run-as\\\" and \\\"server\\\" ideas were somewhat competing.\\n\\nAs far as not changing the connection string goes, a few more ideas\\nhave entered the fray: the current patch uses a password_required\\nproperty that is modelled on postgres_fdw, and I've elsewhere proposed\\na reverse pg_hba.conf.\\n\\nIMHO, for the use cases that I can imagine, the reverse pg_hba.conf\\nidea feels better than all competitors, because it's the only idea\\nthat lets you define a class of acceptable connection strings. Jeff's\\nidea of a separate connection object is fine if you have a specific,\\nshort list of connection strings and you want to allow those and\\ndisallow everything else, and there may be cases where people want\\nthat, and that's fine, but my guess is that it's overly restrictive in\\na lot of environments. The password_required property has the virtue\\nof being compatible with what we do in other places right now, and of\\npreventing wraparound-to-superuser attacks effectively, but it's\\ntotally unconfigurable and that sucks. The runas user idea gives you\\nsome control over who is allowed to set the connection string, but it\\ndoesn't help you delegate that to a non-superuser, because the idea\\nthere is that you want the non-superuser to be able to set connection\\nstrings that are OK with the actual superuser but not others.\\n\\nI think part of my confusion here is that I thought that the point of\\nthe runas user was to defend against logical replication itself\\nchanging the connection string, and I don't see how it would do that.\\nIt's just moving rows around. If the point is that somebody who can\\nlog in as the runas user might change the connection string to\\nsomething we don't like, that makes somewhat more sense. I think I had\\nin my head that you wouldn't use someone's actual login role to run\\nlogical replication, but rather some role specifically set up for that\\npurpose. In that scenario, nobody's running SQL commands as the runas\\nuser, so even if they also own the subscription, there's no way for it\\nto get modified.\\n\\n> > Mark was postulating a scenario where the publisher and subscriber\\n> > don't trust each other. I was thinking a little bit more about that. I\\n> > still maintain that the current system is poorly set up to make that\\n> > work, but suppose we wanted to do better. We could add filtering on\\n> > the subscriber side, like you list schemas or specific relations that\\n> > you are or are not willing to replicate into. Then you could, for\\n> > example, connect your subscription to a certain remote publication,\\n> > but with the restriction that you're only willing to replicate into\\n> > the \\\"headquarters\\\" schema. Then we'll replicate whatever tables they\\n> > send us, but if the dorks at headquarters mess up the publications on\\n> > their end (intentionally or otherwise) and add some tables from the\\n> > \\\"locally_controlled_stuff\\\" schema, we'll refuse to replicate that into\\n> > our eponymous schema.\\n>\\n> That example is good, though I don't see how \\\"filters\\\" are better than roles+privileges. Care to elaborate?\\n\\nI'm not sure that they are. Are we assuming that the user who is\\ncreating subscriptions is also powerful enough to create roles and\\ngive them just the required amount of privilege? If so, it seems like\\nthey might as well just do it that way. And maybe we should assume\\nthat, because in most cases, a dedication replication role makes more\\nsense to me than running replication under some role that you're also\\nusing for other things. On the other hand, I bet a lot of people today\\nare just running replication as a superuser, in which case maybe this\\ncould be useful? This whole idea was mostly just me spitballing to see\\nwhat other people thought. I'm not wild about the complexity involved\\nfor what you get out of it, so if we don't need it, that's more than\\nfine with me.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Feb 2023 09:11:17 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 1, 2023 at 3:37 PM Andres Freund <andres@anarazel.de> wrote:\\n> The general point is that IMO is that in many setups you should use a\\n> user with fewer privileges than a superuser. It doesn't really matter\\n> whether we have an ad-hoc restriction for system catalogs. More often\\n> than not being able to modify other tables will give you a lot of\\n> privileges too.\\n\\nI don't know what you mean by this. DML doesn't confer privileges. If\\ncode gets executed and runs with the replication user's credentials,\\nthat could lead to privilege escalation, but just moving rows around\\ndoesn't, at least not in the database sense. It might confer\\nunanticipated real-world benefits, like if you can update your own\\nsalary or something, but in the context of replication you have to\\nhave had the ability to do that on some other node anyway. If that\\nchange wasn't supposed to get replicated to the local node, then why\\nare we using replication? Or why is that table in the publication? I'm\\nconfused.\\n\\n> > The thing I'm struggling to understand is: if you only want to\\n> > replicate into tables that Alice can write, why not just make Alice\\n> > own the subscription?\\n>\\n> Because it implies that the replication happens as a user that's\\n> privileged enough to change the configuration of replication.\\n\\nBut again, replication is just about inserting, updating, and deleting\\nrows. To change the replication configuration, you have to be able to\\nparlay that into the ability to execute code. That's why I think\\ntrigger security is really important. But I'm wondering if there's\\nsome way we can handle that that doesn't require us to make a decision\\nabout arun-as user. For instance, if firing triggers as the table\\nowner is an acceptable solution, then the only thing that the run-as\\nuser is actually controlling is which tables we're willing to\\nreplicate into in the first place (unless there's some other way that\\nlogical replication can run arbitrary code). The name almost becomes a\\nmisnomer in that case. It's not a run-as user, it's\\nuse-this-user's-permissions-to-see-if-I-should-fail-replication user.\\n\\n> > I was thinking a little bit more about that. I\\n> > still maintain that the current system is poorly set up to make that\\n> > work, but suppose we wanted to do better. We could add filtering on\\n> > the subscriber side, like you list schemas or specific relations that\\n> > you are or are not willing to replicate into.\\n>\\n> Isn't that largely a duplication of the ACLs on relations etc?\\n\\nYeah, maybe.\\n\\n> > I'm not quite sure what we do here now, but I agree that trigger\\n> > firing seems like a problem. It might be that we need to worry about\\n> > the user on the origin server, too. If Alice inserts a row that causes\\n> > a replicated table owned by Bob to fire a trigger or evaluate a\\n> > default expression or whatever due the presence of a subscription\\n> > owned by Charlie, there is a risk that Alice might try to attack\\n> > either Bob or Charlie, or that Bob might try to attack Charlie.\\n>\\n> The attack on Bob exists without logical replication too - a REINDEX or\\n> such is executed as the owner of the relation and re-evaluates index\\n> expressions, constraints etc. Given our security model I don't think we\\n> can protect the relation owner if they trust somebody to insert rows, so\\n> I don't really know what we can do to protect Charlie against Bob.\\n\\nYikes.\\n\\n> > > > And if we suppose that that already works and is safe, well then\\n> > > > what's the case where I do need a run-as user?\\n> > >\\n> > > It's not at all safe today, IMO. You need to trust that nothing bad will\\n> > > be replicated, otherwise the owner of the subscription has to be\\n> > > considered compromised.\\n> >\\n> > What kinds of things are bad to replicate?\\n>\\n> I think that's unfortunately going to be specific to a setup.\\n\\nCan you give an example?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Feb 2023 09:28:03 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-02 09:28:03 -0500, Robert Haas wrote:\\n> I don't know what you mean by this. DML doesn't confer privileges. If\\n> code gets executed and runs with the replication user's credentials,\\n> that could lead to privilege escalation, but just moving rows around\\n> doesn't, at least not in the database sense.\\n\\nExecuting DML ends up executing code. Think predicated/expression\\nindexes, triggers, default expressions etc. If a badly written trigger\\netc can be tricked to do arbitrary code exec, an attack will be able to\\nrun with the privs of the run-as user. How bad that is is influenced to\\nsome degree by the amount of privileges that user has.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Feb 2023 00:47:48 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 1, 2023 at 3:37 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > I'm not an expert on this stuff, but to me that feels like a weak and\\n> > fuzzy concept. If the client is going to tell the server something,\\n> > I'd much rather have it say something like \\\"i'm proxying a request\\n> > from my local user rhaas, who authenticated using such and such a\\n> > method and connected from such and such an IP yadda yadda\\\". That feels\\n> > to me like really clear communication that the server can then be\\n> > configured to something about via pg_hba.conf or similar. Saying \\\"use\\n> > in-band authentication only\\\", to me, feels much murkier. As the\\n> > recipient of that message, I don't know exactly what to do about it,\\n> > and it feels like whatever heuristic I adopt might end up being wrong\\n> > and something bad happens anyway.\\n>\\n> Is it maybe just a matter of terminology? If a proxy tells the server,\\n> \\\"This user is logging in. Here's the password I have for them. DO NOT\\n> authenticate using anything else,\\\" and the HBA says to use ident auth\\n> for that user, then the server fails the connection. That's what I\\n> mean by in-band -- the proxy says, \\\"here are the credentials for this\\n> connection.\\\" That's it.\\n\\nI don't think that's quite the right concept. It seems to me that the\\nclient is responsible for informing the server of what the situation\\nis, and the server is responsible for deciding whether to allow the\\nconnection. In your scenario, the client is not only communicating\\ninformation (\\\"here's the password I have got\\\") but also making demands\\non the server (\\\"DO NOT authenticate using anything else\\\"). I like the\\nfirst part fine, but not the second part.\\n\\nConsider the scenario where somebody wants to allow a connection that\\nis proxied and does not require a password. For example, maybe I have\\na group of three machines that all mutually trust each other and the\\nnetwork is locked down so that we need not worry about IP spoofing or\\nwhatever. Just be doubly sure, they all have SSL certificates so that\\nthey can verify that an incoming connection is from one of the other\\ntrusted machines. I, as the administrator, want to configure things so\\nthat each machine will proxy connections to the others as long as\\nlocal user = remote user. When the remote machine receives the\\nconnection, it can trust that the request is legitimate provided that\\nthe SSL certificate is successfully verified.\\n\\nThe way I think this should work is, first, on each machine, in the\\nproxy configuration, there should be a rule that says \\\"only proxy\\nconnections where local user = remote user\\\" (and any other rules I\\nwant to enforce). Second, in the HBA configuration, there should be a\\nrule that says \\\"if somebody is trying to proxy a connection, it has to\\nbe for one of these IPs and they have to authenticate using an SSL\\ncertificate\\\". In this kind of scenario, the client has no business\\ndemanding that the server authenticate using the password rather than\\nanything else. The server, not the client, is in charge of deciding\\nwhich connections to accept; the client's job is only to decide which\\nconnections to proxy. And the human being is responsible for making\\nsure that the combination of those two things implements the intended\\nsecurity policy.\\n\\n> Agreed. The danger from my end is, I'm trained on configuration\\n> formats that have infinite bells and whistles. I don't really want to\\n> go too crazy with it.\\n\\nYeah. If I remember my math well enough, the time required to\\nimplement infinite bells and whistles will also be infinite, and as a\\nwise man once said, real artists ship.\\n\\nIt does seem like a good idea, if we can, to make the configuration\\nfile format flexible enough that we can easily extend it with more\\nbells and whistles later if we so choose. But realistically most\\npeople are going to have very simple configurations.\\n\\n> > and that maybe\\n> > has something in common with our existing configuration file syntaxes.\\n> > But if we have to invent something new, then we can do that.\\n>\\n> Okay. Personally I'd like\\n> - the ability to set options globally (so filters are optional)\\n> - the ability to maintain many options for a specific scope (host? IP\\n> range?) without making my config lines grow without bound\\n> - the ability to audit a configuration without trusting its comments\\n>\\n> But getting all of my wishlist into a sane configuration format that\\n> handles all the use cases is the tricky part. I'll think about it.\\n\\nNobody seemed too keen on my proposal of a bunch of tab-separated\\nfields; maybe we're all traumatized from pg_hba.conf and should look\\nfor something more complex with a real parser. I thought that\\ntab-separated fields might be good enough and simple to implement, but\\nit doesn't matter how simple it is to implement if nobody likes it. We\\ncould do something that looks more like a series of if-then rules,\\ne.g.\\n\\ntarget-host 127.0.0.0/8 => reject\\nauthentication-method scram => accept\\nreject\\n\\nBut it's only a hop, skip and a jump from there to something that\\nlooks an awful lot like a full-blown programing language, and maybe\\nthat's even the right idea, but, oh, the bike-shedding!\\n\\nCue someone to suggest that it's about time we embed a Lua interpreter.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Feb 2023 11:22:11 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Fri, Feb 3, 2023 at 3:47 AM Andres Freund <andres@anarazel.de> wrote:\\n> On 2023-02-02 09:28:03 -0500, Robert Haas wrote:\\n> > I don't know what you mean by this. DML doesn't confer privileges. If\\n> > code gets executed and runs with the replication user's credentials,\\n> > that could lead to privilege escalation, but just moving rows around\\n> > doesn't, at least not in the database sense.\\n>\\n> Executing DML ends up executing code. Think predicated/expression\\n> indexes, triggers, default expressions etc. If a badly written trigger\\n> etc can be tricked to do arbitrary code exec, an attack will be able to\\n> run with the privs of the run-as user. How bad that is is influenced to\\n> some degree by the amount of privileges that user has.\\n\\nI spent some time studying this today. I think you're right. What I'm\\nconfused about is: why do we consider this situation even vaguely\\nacceptable? Isn't this basically an admission that our logical\\nreplication security model is completely and totally broken and we\\nneed to fix it somehow and file for a CVE number? Like, in released\\nbranches, you can't even have a subscription owned by a non-superuser.\\nBut any non-superuser can set a default expression or create an enable\\nalways trigger and sure enough, if that table is replicated, the\\nsystem will run that trigger as the subscription owner, who is a\\nsuperuser. Which AFAICS means that if a non-superuser owns a table\\nthat is part of a subscription, they can instantly hack superuser.\\nWhich seems, uh, extremely bad. Am I missing something?\\n\\nBased on other remarks you made upthread, it seems like we ought to be\\ndoing the actual replication as the table owner, since the table owner\\nhas to be prepared for executable code attached to the table to be\\nre-run on rows in the table at any table when somebody does a REINDEX.\\nAnd then, in master, where there's some provision for non-superuser\\nsubscription owners, we maybe need to re-think the privileges required\\nto replicate into a table in the first place. I don't think that\\nhaving I/U/D permissions on a table is really sufficient to justify\\nperforming those operations *as the table owner*; perhaps the check\\nought to be whether you have the privileges of the table owner.\\n\\n--\\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Feb 2023 14:07:39 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-06 14:07:39 -0500, Robert Haas wrote:\\n> On Fri, Feb 3, 2023 at 3:47 AM Andres Freund <andres@anarazel.de> wrote:\\n> > On 2023-02-02 09:28:03 -0500, Robert Haas wrote:\\n> > > I don't know what you mean by this. DML doesn't confer privileges. If\\n> > > code gets executed and runs with the replication user's credentials,\\n> > > that could lead to privilege escalation, but just moving rows around\\n> > > doesn't, at least not in the database sense.\\n> >\\n> > Executing DML ends up executing code. Think predicated/expression\\n> > indexes, triggers, default expressions etc. If a badly written trigger\\n> > etc can be tricked to do arbitrary code exec, an attack will be able to\\n> > run with the privs of the run-as user. How bad that is is influenced to\\n> > some degree by the amount of privileges that user has.\\n> \\n> I spent some time studying this today. I think you're right. What I'm\\n> confused about is: why do we consider this situation even vaguely\\n> acceptable? Isn't this basically an admission that our logical\\n> replication security model is completely and totally broken and we\\n> need to fix it somehow and file for a CVE number? Like, in released\\n> branches, you can't even have a subscription owned by a non-superuser.\\n> But any non-superuser can set a default expression or create an enable\\n> always trigger and sure enough, if that table is replicated, the\\n> system will run that trigger as the subscription owner, who is a\\n> superuser. Which AFAICS means that if a non-superuser owns a table\\n> that is part of a subscription, they can instantly hack superuser.\\n> Which seems, uh, extremely bad. Am I missing something?\\n\\nIt's decidedly not great, yes. I don't know if it's quite a CVE type issue,\\nafter all, the same is true for any other type of query the superuser\\nexecutes. But at the very least the documentation needs to be better, with a\\nbig red box making sure the admin is aware of the problem.\\n\\nI think we need some more fundamental ways to deal with this issue, including\\nbut not restricted to the replication context. Some potentially relevant\\ndiscussion is in this thread:\\nhttps://postgr.es/m/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel%40j-davis.com\\n\\nI don't agree with Jeff's proposal, but I think there's some worthwhile ideas\\nin the idea + followups.\\n\\n\\n> And then, in master, where there's some provision for non-superuser\\n> subscription owners, we maybe need to re-think the privileges required\\n> to replicate into a table in the first place. I don't think that\\n> having I/U/D permissions on a table is really sufficient to justify\\n> performing those operations *as the table owner*; perhaps the check\\n> ought to be whether you have the privileges of the table owner.\\n\\nYes, I think we ought to check role membership, including non-inherited\\nmemberships.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Feb 2023 11:18:38 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 6, 2023 at 2:18 PM Andres Freund <andres@anarazel.de> wrote:\\n> It's decidedly not great, yes. I don't know if it's quite a CVE type issue,\\n> after all, the same is true for any other type of query the superuser\\n> executes. But at the very least the documentation needs to be better, with a\\n> big red box making sure the admin is aware of the problem.\\n\\nI don't think that's the same thing at all. A superuser executing a\\nquery interactively can indeed cause all sorts of bad things to\\nhappen, but you don't have to log in as superuser and run DML queries\\non tables owned by unprivileged users, and you shouldn't.\\n\\nBut what we're talking about here is -- the superuser comes along and\\nsets up logical replication in the configuration in what seems to be\\nexactly the way it was intended to be used, and now any user who can\\nlog into the subscriber node can become superuser for free whenever\\nthey want, without the superuser doing anything at all, even logging\\nin. Saying it's \\\"not ideal\\\" seems like you're putting it in the same\\ncategory as \\\"the cheese got moldy in the fridge\\\" but to me it sounds\\nmore like \\\"the fridge exploded and the house is on fire.\\\"\\n\\nIf we were to document this, I assume that the warning we would add to\\nthe documentation would look like this:\\n\\n<-- begin documentation text -->\\nPretty much don't ever use logical replication. In any normal\\nconfiguration, it lets every user on your system escalate to superuser\\nwhenever they want. It is possible to make it safe, if you make sure\\nall the tables on the replica are owned by the superuser and none of\\nthem have any triggers, defaults, expression indexes, or anything else\\nassociated with them that might execute any code while replicating.\\nBut notice that this makes logical replication pretty much useless for\\none of its intended purposes, which is high availability, because if\\nyou actually fail over, you're going to then have to change the owners\\nof all of those tables and apply any missing triggers, defaults,\\nexpression indexes, or anything like that which you may want to have.\\nAnd then to fail back you're going to have to remove all of that stuff\\nagain and once again make the tables superuser-owned. That's obviously\\npretty impractical, so you probably shouldn't use logical replication\\nat all until we get around to fixing this. You might wonder why we\\nimplemented a feature that can't be used in any kind of normal way\\nwithout completely and totally breaking your system security -- but\\ndon't ask us, we don't know, either!\\n<-- end documentation text -->\\n\\nHonestly, this makes the CREATEROLE exploit that I fixed recently in\\nmaster look like a walk in the park. Sure, it's a pain for service\\nproviders, who might otherwise use it, but most normal users don't and\\nwouldn't no matter how it worked, and really are not going to care.\\nBut people do use logical replication, and it seems to me that the\\nissue you're describing here means that approximately 100% of those\\ninstallations have a vulnerability allowing any local user who owns a\\ntable or can create one to escalate to superuser. Far from being not\\nquite a CVE issue, that seems substantially more serious than most\\nthings we get CVEs for.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Feb 2023 14:40:18 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 1, 2023 at 4:02 PM Andres Freund <andres@anarazel.de> wrote:\\n> On 2023-01-30 15:32:34 -0500, Robert Haas wrote:\\n> > I had a long think about what to do with ALTER SUBSCRIPTION ... OWNER\\n> > TO in terms of permissions checks.\\n>\\n> As long as owner and run-as are the same, I think it's strongly\\n> preferrable to *not* require pg_create_subscription.\\n\\nOK.\\n\\n> > Another question around ALTER SUBSCRIPTION ... OWNER TO and also ALTER\\n> > SUBSCRIPTION .. RENAME is whether they ought to fail if you're not a\\n> > superuser and password_required false is set.\\n>\\n> I don't really see a benefit in allowing it, so I'm inclined to go for\\n> the more restrictive option. But this is a really weakly held opinion.\\n\\nI went back and forth on this and ended up with what you propose here.\\nIt's simpler to explain this way.\\n\\n> > + /* Is the use of a password mandatory? */\\n> > + must_use_password = MySubscription->passwordrequired &&\\n> > + !superuser_arg(MySubscription->owner);\\n>\\n> There's a few repetitions of this - perhaps worth putting into a helper?\\n\\nI don't think so. It's slightly different each time, because it's\\npulling data out of different data structures.\\n\\n> This still leaks the connection on error, no?\\n\\nI've attempted to fix this in v4, attached.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 7 Feb 2023 16:56:55 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 2/6/23 08:22, Robert Haas wrote:\\n> I don't think that's quite the right concept. It seems to me that the\\n> client is responsible for informing the server of what the situation\\n> is, and the server is responsible for deciding whether to allow the\\n> connection. In your scenario, the client is not only communicating\\n> information (\\\"here's the password I have got\\\") but also making demands\\n> on the server (\\\"DO NOT authenticate using anything else\\\"). I like the\\n> first part fine, but not the second part.\\n\\nFor what it's worth, making a negative demand during authentication is\\npretty standard: if you visit example.com and it tells you \\\"I need your\\nOS login password and Social Security Number to authenticate you,\\\" you\\nhave the option of saying \\\"no thanks\\\" and closing the tab.\\n\\nIt's not really about protecting the server at that point; the server\\ncan protect itself. It's about protecting *you*. Allowing the proxy to\\npin a specific set of authentication details to the connection is just a\\nway for it to close the tab on a server that would otherwise pull some\\nother piece of ambient authority out of it.\\n\\nIn a hypothetical world where the server presented the client with a\\nlist of authentication options before allowing any access, this would\\nmaybe be a little less convoluted to solve. For example, a proxy seeing\\na SASL list of\\n\\n- ANONYMOUS\\n- EXTERNAL\\n\\ncould understand that both methods allow the client to assume the\\nauthority of the proxy itself. So if its client isn't allowed to do\\nthat, the proxy realizes something is wrong (either it, or its target\\nserver, has been misconfigured or is under attack), and it can close the\\nconnection *before* the server runs login triggers.\\n\\n> In this kind of scenario, the client has no business\\n> demanding that the server authenticate using the password rather than\\n> anything else. The server, not the client, is in charge of deciding\\n> which connections to accept; the client's job is only to decide which\\n> connections to proxy.\\n\\nThis sounds like a reasonable separation of responsibilities on the\\nsurface, but I think it's subtly off. The entire confused-deputy problem\\nspace revolves around the proxy being unable to correctly decide which\\nconnections to allow unless it also knows why the connections are being\\nauthorized.\\n\\nYou've constructed an example where that's not a concern: everything's\\nsymmetrical, all proxies operate with the same authority, and internal\\nusers are identical to external users. But the CVE that led to the\\npassword requirement, as far as I can tell, dealt with asymmetry. The\\nproxy had the authority to connect locally to a user, and the clients\\nhad the authority to connect to other machines' users, but those users\\nweren't the same and were not mutually trusting.\\n\\n> And the human being is responsible for making\\n> sure that the combination of those two things implements the intended\\n> security policy.\\n\\nSure, but upthread it was illustrated how difficult it is for even the\\npeople implementing the protocol to reason through what's safe and\\nwhat's not.\\n\\nThe primitives we're providing in the protocol are, IMO, difficult to\\nwield safely for more complex use cases. We can provide mitigations, and\\ndemand that the DBA reason through every combination, and tell them\\n\\\"don't do that\\\" when they screw up or come across a situation that our\\nmitigations can't paper over. But I think we can solve the root problem\\ninstead.\\n\\n> We\\n> could do something that looks more like a series of if-then rules,\\n> e.g.\\n> \\n> target-host 127.0.0.0/8 => reject\\n> authentication-method scram => accept\\n> reject\\n\\nYeah, I think something based on allow/deny is going to be the most\\nintuitive.\\n\\n> But it's only a hop, skip and a jump from there to something that\\n> looks an awful lot like a full-blown programing language, and maybe\\n> that's even the right idea, but, oh, the bike-shedding!\\n\\nEh. Someone will demand Turing-completeness eventually, but you don't\\nhave to listen. :D\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Feb 2023 13:46:04 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-02-06 at 14:40 -0500, Robert Haas wrote:\\n> On Mon, Feb 6, 2023 at 2:18 PM Andres Freund <andres@anarazel.de>\\n> wrote:\\n> > It's decidedly not great, yes. I don't know if it's quite a CVE\\n> > type issue,\\n> > after all, the same is true for any other type of query the\\n> > superuser\\n> > executes. But at the very least the documentation needs to be\\n> > better, with a\\n> > big red box making sure the admin is aware of the problem.\\n> \\n> I don't think that's the same thing at all. A superuser executing a\\n> query interactively can indeed cause all sorts of bad things to\\n> happen, but you don't have to log in as superuser and run DML queries\\n> on tables owned by unprivileged users, and you shouldn't.\\n\\nThere are two questions:\\n\\n1. Is the security situation with logical replication bad? Yes. You\\nnicely summarized just how bad.\\n\\n2. Is it the same situation as accessing a table owned by a user you\\ndon't absolutely trust? \\n\\nRegardless of how the second question is answered, it won't diminish\\nyour point that logical replication is in a bad state. If another\\nsituation is also bad, we should fix that too.\\n\\nAnd I think the DML situation is really bad, too. Anyone reading our\\ndocumentation would find extensive explanations about GRANT/REVOKE, and\\npuzzle over the fine details of exactly how much they trust user foo.\\nDo I trust foo enough for WITH GRANT OPTION? Does foo really need to\\nsee all of the columns of this table, or just a subset?\\n\\nBut there's no obvious mention that user foo must trust you absolutely\\nin order to exercise the GRANT at all, because you (as table owner) can\\ntrivially cause foo to execute arbitrary code. There's no warning or\\nhint or suggestion at runtime to know that you are about to execute\\nsomeone else's code with your privileges or that it might be dangerous.\\n\\nIt gets worse. Let's say that user foo figures that out, and they're\\nextra cautious to SET SESSION AUTHORIZATION or SET ROLE to drop their\\nprivileges before accessing a table. No good: the table owner can just\\ncraft their arbitrary code with a \\\"RESET SESSION AUTHORIZATION\\\" or a\\n\\\"RESET ROLE\\\" at the top, and the code will still execute with the\\nprivileges of user foo.\\n\\nSo I don't think \\\"shouldn't\\\" is quite good enough. In the first place,\\nthe user needs to know that the risk exists. Second, what if they\\nactually do want to access a table owned by someone else for whatever\\nreason -- how do they do that safely?\\n\\nI can't resist mentioning that these are all SECURITY INVOKER problems.\\nSECURITY INVOKER is insecure unless the invoker absolutely trusts the\\ndefiner, and that only really makes sense if the definer is a superuser\\n(or something very close). That's why we keep adding exceptions with\\nSECURITY_RESTRICTED_OPERATION, which is really just a way to silently\\nignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\\n\\nAt some point we need to ask: \\\"when is SECURITY INVOKER both safe and\\nuseful?\\\" and contain it to those cases, rather than silently ignoring\\nit in an expanding list of cases.\\n\\nI know that the response here is that SECURITY DEFINER is somehow\\nworse. Maybe for superuser-defined functions, it is. But basically, the\\nproblems with SECURITY DEFINER all amount to \\\"the author of the code\\nneeds to be careful\\\", which is a lot more intuitive than the problems\\nwith SECURITY INVOKER.\\n\\nAnother option is having some kind SECURITY NONE that would run the\\ncode as a very limited-privilege user that can basically only access\\nthe catalog. That would be useful for running default expressions and\\nthe like without the definer or invoker needing to be careful.\\n\\n\\n-- \\nJeff Davis\\nPostgreSQL Contributor Team - AWS\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Feb 2023 09:18:34 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Feb 22, 2023, at 9:18 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> Another option is having some kind SECURITY NONE that would run the\\n> code as a very limited-privilege user that can basically only access\\n> the catalog. That would be useful for running default expressions and\\n> the like without the definer or invoker needing to be careful.\\n\\nAnother option is to execute under the intersection of their privileges, where both the definer and the invoker need the privileges in order for the action to succeed. That would be more permissive than the proposed SECURITY NONE, while still preventing either party from hijacking privileges of the other.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Feb 2023 09:27:19 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\\n> Another option is to execute under the intersection of their\\n> privileges, where both the definer and the invoker need the\\n> privileges in order for the action to succeed. That would be more\\n> permissive than the proposed SECURITY NONE, while still preventing\\n> either party from hijacking privileges of the other.\\n\\nInteresting idea, I haven't heard of something like that being done\\nbefore. Is there some precedent for that or a use case where it's\\nhelpful?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Feb 2023 10:49:42 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Feb 22, 2023, at 10:49 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n> \\n> On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\\n>> Another option is to execute under the intersection of their\\n>> privileges, where both the definer and the invoker need the\\n>> privileges in order for the action to succeed. That would be more\\n>> permissive than the proposed SECURITY NONE, while still preventing\\n>> either party from hijacking privileges of the other.\\n> \\n> Interesting idea, I haven't heard of something like that being done\\n> before. Is there some precedent for that or a use case where it's\\n> helpful?\\n\\nNo current use case comes to mind, but I proposed it for event triggers one or two development cycles ago, to allow for non-superuser event trigger owners. The problems associated with allowing non-superusers to create and own event triggers were pretty similar to the problems being discussed in this thread.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Feb 2023 11:12:05 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 2/22/23 14:12, Mark Dilger wrote:\\n>> On Feb 22, 2023, at 10:49 AM, Jeff Davis <pgsql@j-davis.com> wrote:\\n>> On Wed, 2023-02-22 at 09:27 -0800, Mark Dilger wrote:\\n>>> Another option is to execute under the intersection of their\\n>>> privileges, where both the definer and the invoker need the\\n>>> privileges in order for the action to succeed. That would be more\\n>>> permissive than the proposed SECURITY NONE, while still preventing\\n>>> either party from hijacking privileges of the other.\\n>> \\n>> Interesting idea, I haven't heard of something like that being done\\n>> before. Is there some precedent for that or a use case where it's\\n>> helpful?\\n> > No current use case comes to mind, but I proposed it for event\\n> triggers one or two development cycles ago, to allow for\\n> non-superuser event trigger owners. The problems associated with\\n> allowing non-superusers to create and own event triggers were pretty\\n> similar to the problems being discussed in this thread.\\n\\n\\nThe intersection of privileges is used, for example, in multi-level \\nsecurity contexts where the intersection of the network-allowed levels \\nand the subject allowed levels is used to bracket what can be accessed \\nand how.\\n\\nOther examples I found with a quick search:\\n\\nhttps://docs.oracle.com/javase/8/docs/api/java/security/AccessController.html#doPrivileged-java.security.PrivilegedAction-java.security.AccessControlContext-\\n\\nhttps://learn.microsoft.com/en-us/dotnet/api/system.security.permissions.dataprotectionpermission.intersect?view=dotnet-plat-ext-7.0\\n\\n\\n-- \\nJoe Conway\\nPostgreSQL Contributors Team\\nRDS Open Source Databases\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Feb 2023 15:25:44 -0500\",\n \"msg_from\": \"Joe Conway <mail@joeconway.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 22, 2023 at 12:18 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> There are two questions:\\n>\\n> 1. Is the security situation with logical replication bad? Yes. You\\n> nicely summarized just how bad.\\n>\\n> 2. Is it the same situation as accessing a table owned by a user you\\n> don't absolutely trust?\\n>\\n> Regardless of how the second question is answered, it won't diminish\\n> your point that logical replication is in a bad state. If another\\n> situation is also bad, we should fix that too.\\n\\nWell said.\\n\\n> So I don't think \\\"shouldn't\\\" is quite good enough. In the first place,\\n> the user needs to know that the risk exists. Second, what if they\\n> actually do want to access a table owned by someone else for whatever\\n> reason -- how do they do that safely?\\n\\nGood question. I don't think we currently have a good answer.\\n\\n> I can't resist mentioning that these are all SECURITY INVOKER problems.\\n> SECURITY INVOKER is insecure unless the invoker absolutely trusts the\\n> definer, and that only really makes sense if the definer is a superuser\\n> (or something very close). That's why we keep adding exceptions with\\n> SECURITY_RESTRICTED_OPERATION, which is really just a way to silently\\n> ignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\\n\\nThat's an interesting way to look at it. I think there are perhaps two\\ndifferent possible perspectives here. One possibility is to take the\\nview that you've adopted here, and blame it on SECURITY INVOKER. The\\nother possibility, at least as I see it, is to blame it on the fact\\nthat we have so many places to attach executable code to tables and\\nvery few ways for people using those tables to limit their exposure to\\nsuch code. Suppose Alice owns a table and attaches a trigger to it. If\\nBob inserts into that table, I think we have to run the trigger,\\nbecause Alice is entitled to assume that, for example, any BEFORE\\ntriggers she might have defined that block certain kinds of inserts\\nare actually going to block those inserts; any constraints that she\\nhas applied to the table are going to be enforced against all new\\nrows; and any default expressions she supplies are actually going to\\nwork. I think Bob has to be OK with those things too; otherwise, he\\njust shouldn't insert anything into the table.\\n\\nBut Bob doesn't have to be OK with Alice's code changing the session\\nstate, or executing DML or DDL with his permissions. I wonder if\\nthat's where we should be trying to insert restrictions here. Right\\nnow, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\\nfunction or procedure that runs under a different user ID than the\\nsession user from poisoning the session state. But I'm thinking that\\nmaybe the problem isn't really with code running under a different\\nuser ID. It's with running code *provided by* a different user ID.\\nMaybe we should stop thinking about the security context as something\\nthat you set when you switch to running as a different user ID, and\\nstart thinking about it as something that needs to be set based on the\\nrelationship between the user that provided the code and the session\\nuser. If they're not the same, some restrictions are probably\\nappropriate, except I think in the case where the user who provided\\nthe code can become the session user anyway.\\n\\n> Another option is having some kind SECURITY NONE that would run the\\n> code as a very limited-privilege user that can basically only access\\n> the catalog. That would be useful for running default expressions and\\n> the like without the definer or invoker needing to be careful.\\n\\nThis might be possible, but I have some doubts about how difficult it\\nwould be to get all the details right. We'd need to make sure that\\nthis limited-privilege user couldn't ever create a table, or own one,\\nor be granted any privileges to do anything other than the minimal set\\nof things it's supposed to be able to do, or poison the session state,\\netc. And it would have weird results like current_user returning the\\nname of the limited-privilege user rather than any of the users\\ninvolved in the operation. Maybe that's all OK, but I find it more\\nappealing to try to think about what kinds of operations can be\\nperformed in what contexts than to invent entirely new users.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Feb 2023 10:45:06 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-02-27 at 10:45 -0500, Robert Haas wrote:\\n\\n> Suppose Alice owns a table and attaches a trigger to it. If\\n> Bob inserts into that table, I think we have to run the trigger,\\n> because Alice is entitled to assume that, for example, any BEFORE\\n> triggers she might have defined that block certain kinds of inserts\\n> are actually going to block those inserts; any constraints that she\\n> has applied to the table are going to be enforced against all new\\n> rows; and any default expressions she supplies are actually going to\\n> work.\\n\\nTrue, but I still find myself suspending my disbelief. Which of these\\nuse cases make sense for SECURITY INVOKER?\\n\\n> I think Bob has to be OK with those things too; otherwise, he\\n> just shouldn't insert anything into the table.\\n\\nRight, but why should Bob's privileges be needed to do any of those\\nthings? Any difference in privileges, for those use cases, could only\\neither get in the way of achieving Alice's goals, or cause a security\\nproblem for Bob.\\n\\n> But Bob doesn't have to be OK with Alice's code changing the session\\n> state, or executing DML or DDL with his permissions.\\n\\nWhat's left? Should Bob be OK with Alice's code using his permissions\\nfor anything?\\n\\n> I wonder if\\n> that's where we should be trying to insert restrictions here. Right\\n> now, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\\n> function or procedure that runs under a different user ID than the\\n> session user from poisoning the session state. But I'm thinking that\\n> maybe the problem isn't really with code running under a different\\n> user ID. It's with running code *provided by* a different user ID.\\n> Maybe we should stop thinking about the security context as something\\n> that you set when you switch to running as a different user ID, and\\n> start thinking about it as something that needs to be set based on\\n> the\\n> relationship between the user that provided the code and the session\\n> user. If they're not the same, some restrictions are probably\\n> appropriate, except I think in the case where the user who provided\\n> the code can become the session user anyway.\\n\\nI think you are saying that we should still run Alice's code with the\\nprivileges of Bob, but somehow make that safe(r) for Bob. Is that\\nright?\\n\\nThat sounds hard, and I'm still stuck at the \\\"why\\\" question. Why do we\\nwant to run Alice's code with Bob's permissions?\\n\\nThe answers I have so far are abstract. For instance, maybe it's a\\nclever SRF that takes table names as inputs and you want people to only\\nbe able to use the clever SRF with tables they have privileges on. But\\nthat's not what most functions do, and it's certainly not what most\\ndefault expressions do.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Feb 2023 10:25:29 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Mon, 2023-02-27 at 10:45 -0500, Robert Haas wrote:\\n> > Suppose Alice owns a table and attaches a trigger to it. If\\n> > Bob inserts into that table, I think we have to run the trigger,\\n> > because Alice is entitled to assume that, for example, any BEFORE\\n> > triggers she might have defined that block certain kinds of inserts\\n> > are actually going to block those inserts; any constraints that she\\n> > has applied to the table are going to be enforced against all new\\n> > rows; and any default expressions she supplies are actually going to\\n> > work.\\n> \\n> True, but I still find myself suspending my disbelief. Which of these\\n> use cases make sense for SECURITY INVOKER?\\n\\nI do think there are some use-cases for it, but agree that it'd be\\nbetter to encourage more use of SECURITY DEFINER and one approach to\\nthat might be to have a way for users to explicitly say \\\"don't run code\\nthat isn't mine or a superuser's with my privileges.\\\" Of course, we\\nneed to make sure it's possible to write safe SECURITY DEFINER functions\\nand to be clear about how to do that to avoid the risk in the other\\ndirection. We also need to provide some additonal functions along the\\nlines of \\\"calling_role()\\\" or similar (so that the function can know who\\nthe actual role is that's running the trigger) for the common case of\\nauditing or needing to know the calling role for RLS or similar.\\n\\nI don't think we'd be able to get away with just getting rid of SECURITY\\nINVOKER entirely or even in changing the current way triggers (or\\nfunctions in views, etc) are run by default.\\n\\n> > I think Bob has to be OK with those things too; otherwise, he\\n> > just shouldn't insert anything into the table.\\n> \\n> Right, but why should Bob's privileges be needed to do any of those\\n> things? Any difference in privileges, for those use cases, could only\\n> either get in the way of achieving Alice's goals, or cause a security\\n> problem for Bob.\\n> \\n> > But Bob doesn't have to be OK with Alice's code changing the session\\n> > state, or executing DML or DDL with his permissions.\\n> \\n> What's left? Should Bob be OK with Alice's code using his permissions\\n> for anything?\\n\\nI don't know about trying to define that X things are ok and Y things\\nare not, that seems like it would be more confusing and difficult to\\nwork with. Regular SELECT queries that pull data that Bob has access to\\nbut Alice doesn't is a security issue too, were Alice to install a\\nfunction that Bob calls which writes that data into a place that Alice\\ncould then access it. Perhaps if we could allow Bob to say \\\"these\\nthings are ok for Alice's code to access\\\" then it could work ... but if\\nthat's what is going on then the code could run with Alice's permissions\\nand Bob could use our nice and granular GRANT/RLS system to say what\\nAlice is allowed to access.\\n\\n> > I wonder if\\n> > that's where we should be trying to insert restrictions here. Right\\n> > now, we think of SECURITY_RESTRICTED_OPERATION as a way to prevent a\\n> > function or procedure that runs under a different user ID than the\\n> > session user from poisoning the session state. But I'm thinking that\\n> > maybe the problem isn't really with code running under a different\\n> > user ID. It's with running code *provided by* a different user ID.\\n> > Maybe we should stop thinking about the security context as something\\n> > that you set when you switch to running as a different user ID, and\\n> > start thinking about it as something that needs to be set based on\\n> > the\\n> > relationship between the user that provided the code and the session\\n> > user. If they're not the same, some restrictions are probably\\n> > appropriate, except I think in the case where the user who provided\\n> > the code can become the session user anyway.\\n> \\n> I think you are saying that we should still run Alice's code with the\\n> privileges of Bob, but somehow make that safe(r) for Bob. Is that\\n> right?\\n> \\n> That sounds hard, and I'm still stuck at the \\\"why\\\" question. Why do we\\n> want to run Alice's code with Bob's permissions?\\n> \\n> The answers I have so far are abstract. For instance, maybe it's a\\n> clever SRF that takes table names as inputs and you want people to only\\n> be able to use the clever SRF with tables they have privileges on. But\\n> that's not what most functions do, and it's certainly not what most\\n> default expressions do.\\n\\ncurrent_role / current_user are certainly common as a default\\nexpression. I agree that that's more of an edge case that would be nice\\nto solve in a different way though. I do think there's some other use\\ncases for SECURITY INVOKER but not enough folks understand the security\\nrisk associated with it and it'd be good for us to improve on that\\nsituation.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 27 Feb 2023 14:10:02 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> I think you are saying that we should still run Alice's code with the\\n> privileges of Bob, but somehow make that safe(r) for Bob. Is that\\n> right?\\n\\nYeah. That's the idea I was floating, at least.\\n\\n> That sounds hard, and I'm still stuck at the \\\"why\\\" question. Why do we\\n> want to run Alice's code with Bob's permissions?\\n>\\n> The answers I have so far are abstract. For instance, maybe it's a\\n> clever SRF that takes table names as inputs and you want people to only\\n> be able to use the clever SRF with tables they have privileges on. But\\n> that's not what most functions do, and it's certainly not what most\\n> default expressions do.\\n\\nI guess I have a pretty hard time imagining that we can just\\nobliterate SECURITY INVOKER entirely. It seems fundamentally\\nreasonable to me that Alice might want to make some code available to\\nbe executed in the form of a function or procedure but without\\noffering to execute it with her own privileges. But I think maybe\\nyou're asking a different question, which is whether when the code is\\nattached to a table we ought to categorically switch to the table\\nowner before executing it. I'm less sure about the answer to that\\nquestion. We already take the position that VACUUM always runs as the\\ntable owner, and while VACUUM runs index expressions but not for\\nexample triggers, why not just be consistent and run all code that is\\ntied to the table as the table owner, all the time?\\n\\nMaybe that's the right thing to do, but I think it would inevitably\\nbreak some things for some users. Alice might choose to write her\\ntriggers or default expressions in ways that rely on them running with\\nBob's permissions in any number of ways. For instance, maybe those\\nfunctions issue a SELECT query against an RLS-enabled table, such that\\nthe answer depends on whose privileges are used to run the query. More\\nsimply, she might refer to CURRENT_ROLE, say to record who inserted\\nany particular row into her table, which seems like a totally\\nreasonable thing to want to do. If she was feeling really clever, she\\nmight even have designed queries that she's using inside those\\ntriggers or default expressions to fail if Bob doesn't have enough\\npermissions to do some particular modification that he's attempting,\\nand thus block certain kinds of access to her own tables. That would\\nbe pretty weird and perhaps too clever by half, but the point is that\\nthe current behavior is probably known to many, many users and we\\nreally can't know what they've done that depends on that. If we change\\nany behavior here, some people are going to notice those changes, and\\nthey may not like them.\\n\\nTo put that another way, we're not talking about a black-and-white\\nsecurity vulnerability here, like a buffer overrun that allows for\\narbitrary code execution. We're talking about a set of semantics that\\nseem to be somewhat fragile and vulnerable to spawning security\\nproblems. Nobody wants those security problems, for sure. But it\\ndoesn't follow that nobody is relying on the semantics.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Feb 2023 16:13:59 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-02-27 at 14:10 -0500, Stephen Frost wrote:\\n> I do think there are some use-cases for it, but agree that it'd be\\n> better to encourage more use of SECURITY DEFINER and one approach to\\n> that might be to have a way for users to explicitly say \\\"don't run\\n> code\\n> that isn't mine or a superuser's with my privileges.\\\" \\n\\nI tried that:\\n\\nhttps://www.postgresql.org/message-id/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel@j-davis.com\\n\\nbut Andres pointed out some problems with my implementation. They\\ndidn't seem easily fixable, but perhaps with more effort it could work\\n(run all the expressions as security definer, as well?).\\n\\n> Of course, we\\n> need to make sure it's possible to write safe SECURITY DEFINER\\n> functions\\n> and to be clear about how to do that to avoid the risk in the other\\n> direction.\\n\\nAgreed. Perhaps we can force search_path to be set for SECURITY\\nDEFINER, and require that the temp schema be explicitly included rather\\nthan the current \\\"must be at the end\\\". We could also provide a way to\\nturn public access off in the same statement, so that you don't need to\\nuse a transaction block to keep the function private.\\n\\n> I don't think we'd be able to get away with just getting rid of\\n> SECURITY\\n> INVOKER entirely or even in changing the current way triggers (or\\n> functions in views, etc) are run by default.\\n\\nI didn't propose anything radical. I'm just trying to get some\\nagreement that SECURITY INVOKER is central to a lot of our security\\nwoes, and that we should be treating it with skepticism on a\\nfundamental level.\\n\\nIndividual proposals for how to get away from SECURITY INVOKER should\\nbe evaluated on their merits (i.e. don't break a bunch of stuff).\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Feb 2023 16:03:15 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-02-27 at 16:13 -0500, Robert Haas wrote:\\n> On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > I think you are saying that we should still run Alice's code with\\n> > the\\n> > privileges of Bob, but somehow make that safe(r) for Bob. Is that\\n> > right?\\n> \\n> Yeah. That's the idea I was floating, at least.\\n\\nIsn't that a hard problem; maybe impossible?\\n\\n> \\n> I guess I have a pretty hard time imagining that we can just\\n> obliterate SECURITY INVOKER entirely.\\n\\nOf course not.\\n\\n> It seems fundamentally\\n> reasonable to me that Alice might want to make some code available to\\n> be executed in the form of a function or procedure but without\\n> offering to execute it with her own privileges.\\n\\nIt also seems fundamentally reasonable that if someone grants you\\nprivileges on one of their tables, it might be safe to access it.\\n\\nI'm sure there are a few use cases for SECURITY INVOKER, but they are\\nquite narrow.\\n\\nPerhaps most frustratingly, even if none of the users on a system has\\nany use case for SECURITY INVOKER, they still must all live in fear of\\naccessing each others' tables, because at any time a SECURITY INVOKER\\nfunction could be attached to one of the tables.\\n\\nI feel like we are giving up mainstream utility and safety in exchange\\nfor contrived or exceptional cases. That's not a good trade.\\n\\n> We already take the position that VACUUM always runs as the\\n> table owner, and while VACUUM runs index expressions but not for\\n> example triggers, why not just be consistent and run all code that is\\n> tied to the table as the table owner, all the time?\\n\\nI'd also extend this to default expressions and other code that can be\\nexecuted implicitly.\\n\\n> Maybe that's the right thing to do\\n\\nIf it's the right place to go, then I think we should consider\\nreasonable steps to take in that direction that don't cause unnecessary\\nbreakage.\\n\\n> , but I think it would inevitably\\n> break some things for some users.\\n\\nNot all steps would be breaking changes, and a lot of those steps are\\nthings we should do anyway. We could make it easier to write safe\\nSECURITY DEFINER functions, provide more tools for users to opt-out of\\nexecuting SECURITY INVOKER code, provide a way for superusers to safely\\ndrop privileges, document the problems with security invoker and what\\nto do about them, etc.\\n\\n> Alice might choose to write her\\n> triggers or default expressions in ways that rely on them running\\n> with\\n> Bob's permissions in any number of ways.\\n\\nSure, breakage is possible, and we should mitigate it.\\n\\nBut we also shouldn't exaggerate it -- for instance, others have\\nproposed that we run code as the table owner for logical subscriptions,\\nand that's going to break things in the same way. Arguably, if we are\\ngoing to break something, it's better to break it consistently rather\\nthan one subsystem at a time.\\n\\nBack to the $SUBJECT, if we allow non-superusers to run subscriptions,\\nand the subscription runs the code as the table owner, that might also\\nlead to some weird behavior for triggers that rely on SECURITY INVOKER\\nsemantics.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Feb 2023 16:37:26 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Mon, 2023-02-27 at 14:10 -0500, Stephen Frost wrote:\\n> > I do think there are some use-cases for it, but agree that it'd be\\n> > better to encourage more use of SECURITY DEFINER and one approach to\\n> > that might be to have a way for users to explicitly say \\\"don't run\\n> > code\\n> > that isn't mine or a superuser's with my privileges.\\\" \\n> \\n> I tried that:\\n> \\n> https://www.postgresql.org/message-id/75b0dbb55e9febea54c441efff8012a6d2cb5bd7.camel@j-davis.com\\n> \\n> but Andres pointed out some problems with my implementation. They\\n> didn't seem easily fixable, but perhaps with more effort it could work\\n> (run all the expressions as security definer, as well?).\\n\\nPresumably. Ultimately, I tend to agree it won't be easy. That doesn't\\nmean it's not a worthwhile effort.\\n\\n> > Of course, we\\n> > need to make sure it's possible to write safe SECURITY DEFINER\\n> > functions\\n> > and to be clear about how to do that to avoid the risk in the other\\n> > direction.\\n> \\n> Agreed. Perhaps we can force search_path to be set for SECURITY\\n> DEFINER, and require that the temp schema be explicitly included rather\\n> than the current \\\"must be at the end\\\". We could also provide a way to\\n> turn public access off in the same statement, so that you don't need to\\n> use a transaction block to keep the function private.\\n\\nWe do pretty strongly encourage a search_path setting for SECURITY\\nDEFINER today.. That said, I'm not against pushing on that harder. The\\nissue about temporary schemas is a more difficult issue... but frankly,\\nI'd like an option to say \\\"no temporary schemas should be allowed in my\\nsearch path\\\" when it comes to a security definer function.\\n\\n> > I don't think we'd be able to get away with just getting rid of\\n> > SECURITY\\n> > INVOKER entirely or even in changing the current way triggers (or\\n> > functions in views, etc) are run by default.\\n> \\n> I didn't propose anything radical. I'm just trying to get some\\n> agreement that SECURITY INVOKER is central to a lot of our security\\n> woes, and that we should be treating it with skepticism on a\\n> fundamental level.\\n\\nSure, but if we want to make progress then we have to provide a\\ndirection for folks to go in that's both secure and convenient.\\n\\n> Individual proposals for how to get away from SECURITY INVOKER should\\n> be evaluated on their merits (i.e. don't break a bunch of stuff).\\n\\nOf course. That said ... we don't want to spend a lot of time\\ngoing in a direction that won't bear fruit; I'm hopeful that this\\ndirection will though.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 27 Feb 2023 21:31:47 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> Not all steps would be breaking changes, and a lot of those steps are\\n> things we should do anyway. We could make it easier to write safe\\n> SECURITY DEFINER functions, provide more tools for users to opt-out of\\n> executing SECURITY INVOKER code, provide a way for superusers to safely\\n> drop privileges, document the problems with security invoker and what\\n> to do about them, etc.\\n\\nAgreed.\\n\\n> But we also shouldn't exaggerate it -- for instance, others have\\n> proposed that we run code as the table owner for logical subscriptions,\\n> and that's going to break things in the same way. Arguably, if we are\\n> going to break something, it's better to break it consistently rather\\n> than one subsystem at a time.\\n\\nI tend to agree with this.\\n\\n> Back to the $SUBJECT, if we allow non-superusers to run subscriptions,\\n> and the subscription runs the code as the table owner, that might also\\n> lead to some weird behavior for triggers that rely on SECURITY INVOKER\\n> semantics.\\n\\nIndeed.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 27 Feb 2023 21:38:35 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > Yeah. That's the idea I was floating, at least.\\n>\\n> Isn't that a hard problem; maybe impossible?\\n\\nIt doesn't seem that hard to me; maybe I'm missing something.\\n\\nThe existing SECURITY_RESTRICTED_OPERATION flag basically prevents you\\nfrom tinkering with the session state. If we also had a similar flags\\nlike DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or just\\na combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\\npretty close to what we need. The idea would be that, when a user\\nexecutes a function or procedure owned by a user that they don't trust\\ncompletely, we'd set\\nSECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRITES_PROHIBITED.\\nAnd we could provide a user with a way to express the degree of trust\\nthey have in some other user or perhaps even some specific function,\\ne.g.\\n\\nSET trusted_roles='alice:read';\\n\\n...could mean that I trust alice to read from the database with my\\npermissions, should I happen to run code provided by her in SECURITY\\nINVOKER modacke.\\n\\nI'm sure there's some details to sort out here, e.g. around security\\nrelated to the trusted_roles GUC itself. But I don't really see a\\nfundamental problem. We can invent arbitrary flags that prohibit\\nclasses of operations that are of concern, set them by default in\\ncases where concern is justified, and then give users who want the\\ncurrent behavior some kind of escape hatch that causes those flags to\\nnot get set after all. Not only does such a solution not seem\\nimpossible, I can possibly even imagine back-patching it, depending on\\nexactly what the shape of the final solution is, how important we\\nthink it is to get a fix out there, and how brave I'm feeling that\\nday.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 28 Feb 2023 08:37:02 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-22 09:18:34 -0800, Jeff Davis wrote:\\n> I can't resist mentioning that these are all SECURITY INVOKER problems.\\n> SECURITY INVOKER is insecure unless the invoker absolutely trusts the\\n> definer, and that only really makes sense if the definer is a superuser\\n> (or something very close). That's why we keep adding exceptions with\\n> SECURITY_RESTRICTED_OPERATION, which is really just a way to silently\\n> ignore the SECURITY INVOKER label and use SECURITY DEFINER instead.\\n> \\n> At some point we need to ask: \\\"when is SECURITY INVOKER both safe and\\n> useful?\\\" and contain it to those cases, rather than silently ignoring\\n> it in an expanding list of cases.\\n\\nI can only repeat myself in stating that SECURITY DEFINER solves none of the\\nrelevant issues. I included several examples of why it doesn't in the recent\\nthread about \\\"blocking SECURITY INVOKER\\\". E.g. that default arguments of\\nSECDEF functions are evaluated with the current user's privileges, not the\\nfunction owner's privs:\\n\\nhttps://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 28 Feb 2023 11:28:30 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, 2023-02-28 at 11:28 -0800, Andres Freund wrote:\\n> I can only repeat myself in stating that SECURITY DEFINER solves none\\n> of the\\n> relevant issues. I included several examples of why it doesn't in the\\n> recent\\n> thread about \\\"blocking SECURITY INVOKER\\\". E.g. that default arguments\\n> of\\n> SECDEF functions are evaluated with the current user's privileges,\\n> not the\\n> function owner's privs:\\n> \\n> https://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\\n\\nI was speaking a bit loosely, using \\\"SECURITY DEFINER\\\" to mean the\\nsemantics of executing code as the one who wrote it. I didn't\\nspecifically mean the function marker, because as you pointed out in\\nthe other thread, that's not enough.\\n\\n From your email it looks like there is still a path forward:\\n\\n\\\"The proposal to not trust any expressions controlled by untrusted\\nusers at least allows to prevent execution of code, even if it doesn't\\nprovide a way to execute the code in a safe manner. Given that we\\ndon't have the former, it seems foolish to shoot for the latter.\\\"\\n\\nAnd later:\\n\\n\\\"I think the combination of\\na) a setting that restricts evaluation of any non-trusted expressions,\\n independent of the origin\\nb) an easy way to execute arbitrary statements within\\n SECURITY_RESTRICTED_OPERATION\\\"\\n\\nMy takeaway from that thread was that we need a mechanism to deal with\\nnon-function code (e.g. default expressions) first; but once we have\\nthat, it opens up the design space to better solutions or at least\\nmitigations. Is that right?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 28 Feb 2023 12:36:38 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, 2023-02-28 at 08:37 -0500, Robert Haas wrote:\\n> The existing SECURITY_RESTRICTED_OPERATION flag basically prevents\\n> you\\n> from tinkering with the session state.\\n\\nCurrently, every time we set that flag we also run all the code as the\\ntable owner.\\n\\nYou're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\\nwith the new security flags, but not switch to the table owner, right?\\n\\n> If we also had a similar flags\\n> like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or\\n> just\\n> a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\\n> pretty close to what we need. The idea would be that, when a user\\n> executes a function or procedure \\n\\nOr default expressions, I presume. If we at least agree on this point,\\nthen I think we should try to find a way to treat these other hunks of\\ncode in a secure way (which I think is what Andres was suggesting).\\n\\n> owned by a user that they don't trust\\n> completely, we'd set\\n> SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRIT\\n> ES_PROHIBITED.\\n\\nIt seems like you're saying to basically just keep the user ID the\\nsame, and maybe keep USAGE privileges, but not be able to do anything\\nelse? Might be useful. Kind of like running it as a nobody user but\\nwithout the problems you mentioned. Some details to think about, I'm\\nsure.\\n\\n> And we could provide a user with a way to express the degree of trust\\n> they have in some other user or perhaps even some specific function,\\n> e.g.\\n> \\n> SET trusted_roles='alice:read';\\n> \\n> ...could mean that I trust alice to read from the database with my\\n> permissions, should I happen to run code provided by her in SECURITY\\n> INVOKER modacke.\\n\\nI'm not very excited about inventing a new privilege language inside a\\nGUC, but perhaps a simpler form could be a reasonable mitigation (or at\\nleast a starting place).\\n\\n> I'm sure there's some details to sort out here, e.g. around security\\n> related to the trusted_roles GUC itself. But I don't really see a\\n> fundamental problem. We can invent arbitrary flags that prohibit\\n> classes of operations that are of concern, set them by default in\\n> cases where concern is justified, and then give users who want the\\n> current behavior some kind of escape hatch that causes those flags to\\n> not get set after all. Not only does such a solution not seem\\n> impossible, I can possibly even imagine back-patching it, depending\\n> on\\n> exactly what the shape of the final solution is, how important we\\n> think it is to get a fix out there, and how brave I'm feeling that\\n> day.\\n\\nUnless the trusted roles defaults to '*', then I think it will still\\nbreak some things.\\n\\n\\nOne of my key tests for user-facing proposals is whether the\\ndocumentation will be reasonable or not. Most of these proposals to\\nmake SECURITY INVOKER less bad fail that test.\\n\\nEach of these ideas and sub-ideas affect the semantics, and should be\\ndocumented. But how do we document that some code runs as you, some as\\nthe person who wrote it, sometimes we obey SECURITY INVOKER and\\nsometimes we ignore it and use DEFINER semantics, some code is outside\\na function and always executes as the invoker, some code has some\\nsecurity flags, and some code has more security flags, code can change\\nbetween the time you look at it and the time it runs, and it's all\\nfiltered through GUCs with their own privilege sub-language?\\n\\nOK, let's assume that we have all of that documented, then how do we\\nguide users on what reasonable best practices are for the GUC settings,\\netc.? Or do we just say \\\"this is mechanically how all these parts work,\\ngood luck assembling it into a secure system!\\\". [ Note: I feel like\\nthis is the state we are in now. Even if technically we don't have live\\nsecurity bugs that I'm aware of, we are setting users up for security\\nproblems. ]\\n\\nOn the other hand, if we focus on executing code as the user who wrote\\nit in most places, then the documentation will be something like: \\\"you\\ndefined the table, you wrote the code, it runs as you, here are some\\nbest practices for writing secure code\\\". And we have some different\\ndocumentation for writing a cool SECURITY INVOKER function and how to\\nget other users to trust you enough to run it. That sounds a LOT more\\nunderstandable for users.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 28 Feb 2023 13:01:05 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Tue, 2023-02-28 at 08:37 -0500, Robert Haas wrote:\\n> > The existing SECURITY_RESTRICTED_OPERATION flag basically prevents\\n> > you\\n> > from tinkering with the session state.\\n> \\n> Currently, every time we set that flag we also run all the code as the\\n> table owner.\\n> \\n> You're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\\n> with the new security flags, but not switch to the table owner, right?\\n\\nI'm having trouble following this too, I have to admit. If we aren't\\nchanging who we're running the code under.. but making it so that the\\ncode isn't actually able to do anything then that doesn't strike me as\\nlikely to actually be useful? Surely things like triggers which are\\nused to update another table or insert into another table what happened\\non the table with the trigger need to be allowed to modify the database-\\nhow do we make that possible while the code runs as the invoker and not\\nthe table owner when the table owner is the one who gets to write the\\ncode?\\n\\n> > If we also had a similar flags\\n> > like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or\\n> > just\\n> > a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\\n> > pretty close to what we need. The idea would be that, when a user\\n> > executes a function or procedure \\n> \\n> Or default expressions, I presume. If we at least agree on this point,\\n> then I think we should try to find a way to treat these other hunks of\\n> code in a secure way (which I think is what Andres was suggesting).\\n\\nWould need to apply to functions in views and functions in RLS too,\\nalong wth default expressions and everything else that could be defined\\nby one person and run by another.\\n\\n> > owned by a user that they don't trust\\n> > completely, we'd set\\n> > SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRIT\\n> > ES_PROHIBITED.\\n> \\n> It seems like you're saying to basically just keep the user ID the\\n> same, and maybe keep USAGE privileges, but not be able to do anything\\n> else? Might be useful. Kind of like running it as a nobody user but\\n> without the problems you mentioned. Some details to think about, I'm\\n> sure.\\n\\nWhile there's certainly some use-cases where a completely unprivileged\\nuser would work, there's certainly an awful lot where it wouldn't.\\nHaving that as an option might be interesting for those much more\\nlimited use-cases and maybe you could even say \\\"only run functions which\\nare owned by a superuser or X roles\\\" but it's certainly not a general\\nsolution to the problem.\\n\\n> > And we could provide a user with a way to express the degree of trust\\n> > they have in some other user or perhaps even some specific function,\\n> > e.g.\\n> > \\n> > SET trusted_roles='alice:read';\\n> > \\n> > ...could mean that I trust alice to read from the database with my\\n> > permissions, should I happen to run code provided by her in SECURITY\\n> > INVOKER modacke.\\n> \\n> I'm not very excited about inventing a new privilege language inside a\\n> GUC, but perhaps a simpler form could be a reasonable mitigation (or at\\n> least a starting place).\\n\\nI'm pretty far down the path of \\\"wow that looks really difficult to work\\nwith\\\", to put it nicely.\\n\\n> > I'm sure there's some details to sort out here, e.g. around security\\n> > related to the trusted_roles GUC itself. But I don't really see a\\n> > fundamental problem. We can invent arbitrary flags that prohibit\\n> > classes of operations that are of concern, set them by default in\\n> > cases where concern is justified, and then give users who want the\\n> > current behavior some kind of escape hatch that causes those flags to\\n> > not get set after all. Not only does such a solution not seem\\n> > impossible, I can possibly even imagine back-patching it, depending\\n> > on\\n> > exactly what the shape of the final solution is, how important we\\n> > think it is to get a fix out there, and how brave I'm feeling that\\n> > day.\\n> \\n> Unless the trusted roles defaults to '*', then I think it will still\\n> break some things.\\n\\nDefaulting to an option that is \\\"don't break anything\\\" while giving\\nusers flexibility to test out other, more secure, options seems like it\\nwould be a pretty reasonable way forward, generally. That said.. I\\ndon't really think this particular approach ends up being a good\\ndirection to go in...\\n\\n> One of my key tests for user-facing proposals is whether the\\n> documentation will be reasonable or not. Most of these proposals to\\n> make SECURITY INVOKER less bad fail that test.\\n\\nand this is certainly a very good point as to why.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Tue, 28 Feb 2023 21:22:48 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 28, 2023 at 4:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> You're suggesting using the SECURITY_RESTRICTED_OPERATION flag, along\\n> with the new security flags, but not switch to the table owner, right?\\n\\nCorrect.\\n\\n> Or default expressions, I presume. If we at least agree on this point,\\n> then I think we should try to find a way to treat these other hunks of\\n> code in a secure way (which I think is what Andres was suggesting).\\n\\nYeah, or any other expressions. Basically impose restrictions when the\\nuser running the code is not the same as the user who provided the\\ncode.\\n\\n> It seems like you're saying to basically just keep the user ID the\\n> same, and maybe keep USAGE privileges, but not be able to do anything\\n> else? Might be useful. Kind of like running it as a nobody user but\\n> without the problems you mentioned. Some details to think about, I'm\\n> sure.\\n\\nYep.\\n\\n> I'm not very excited about inventing a new privilege language inside a\\n> GUC, but perhaps a simpler form could be a reasonable mitigation (or at\\n> least a starting place).\\n\\nI'm not very sure about this part, either. I think we need some way of\\nshutting off whatever new controls we impose, but the shape of it is\\nunclear to me and I think there are a bunch of problems.\\n\\n> Unless the trusted roles defaults to '*', then I think it will still\\n> break some things.\\n\\nDefinitely. IMHO, it's OK to break some things, certainly in a major\\nrelease and maybe even in a minor release. But we don't want to break\\nmore things that we really need to break. And as you say, we want the\\nrestrictions to be comprehensible.\\n\\n> Each of these ideas and sub-ideas affect the semantics, and should be\\n> documented. But how do we document that some code runs as you, some as\\n> the person who wrote it, sometimes we obey SECURITY INVOKER and\\n> sometimes we ignore it and use DEFINER semantics, some code is outside\\n> a function and always executes as the invoker, some code has some\\n> security flags, and some code has more security flags, code can change\\n> between the time you look at it and the time it runs, and it's all\\n> filtered through GUCs with their own privilege sub-language?\\n>\\n> OK, let's assume that we have all of that documented, then how do we\\n> guide users on what reasonable best practices are for the GUC settings,\\n> etc.? Or do we just say \\\"this is mechanically how all these parts work,\\n> good luck assembling it into a secure system!\\\". [ Note: I feel like\\n> this is the state we are in now. Even if technically we don't have live\\n> security bugs that I'm aware of, we are setting users up for security\\n> problems. ]\\n>\\n> On the other hand, if we focus on executing code as the user who wrote\\n> it in most places, then the documentation will be something like: \\\"you\\n> defined the table, you wrote the code, it runs as you, here are some\\n> best practices for writing secure code\\\". And we have some different\\n> documentation for writing a cool SECURITY INVOKER function and how to\\n> get other users to trust you enough to run it. That sounds a LOT more\\n> understandable for users.\\n\\nWhat I was imagining is that we would document something like: A table\\ncan have executable code associated with it in a variety of ways. For\\nexample, it can have triggers, default expressions, check constraints,\\nor row-level security filters. In most cases, these expressions are\\nexecuted with the privileges of the user performing the operation on\\nthe table, except when SECURITY DEFINER functions are used. Because\\nthese expressions are set by the table owner and executed by the users\\naccessing the table, there is a risk that the table owner could\\ninclude malicious code that usurps the privileges of the user\\naccessing the table. For this reason, these expressions are, by\\ndefault, restricted from doing <things>. If you want to allow those\\noperations, you can <something>.\\n\\nI agree that running code as the table owner is helpful in a bunch of\\nscenarios, but I also don't think it fixes everything. You earlier\\nmentioned that switching to the table owner seems to be just a way of\\nturning SECURITY INVOKER into SECURITY DEFINER in random places, or\\nmaybe that's not exactly what you said but that's what I took from it.\\nAnd I think that's right. If we just slather user context switches\\neverywhere, I'm not actually very sure that's going to be\\ncomprehensible behavior: if my trigger function is SECURITY INVOKER,\\nwhy is it getting executed as me, not the inserting user? I also think\\nthere are plenty of cases where that could just replace the current\\nset of security problems with a new set of security problems. If the\\ntrigger function is SECURITY INVOKER, then the user who wrote it\\ndoesn't have to worry about securing it against attacks by users\\naccessing the table; it's just running with the permissions of the\\nuser performing the DML. Maybe there are correctness issues if you\\ndon't lock down search_path etc., but there's no security compromise\\nbecause there's no user ID switching. As soon as you magically turn\\nthat into a SECURITY DEFINER function, you've provided a way for the\\nusers performing DML to attack the table owner.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Mar 2023 10:05:42 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Robert Haas (robertmhaas@gmail.com) wrote:\\n> On Tue, Feb 28, 2023 at 4:01 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > Or default expressions, I presume. If we at least agree on this point,\\n> > then I think we should try to find a way to treat these other hunks of\\n> > code in a secure way (which I think is what Andres was suggesting).\\n> \\n> Yeah, or any other expressions. Basically impose restrictions when the\\n> user running the code is not the same as the user who provided the\\n> code.\\n\\nWould this have carve-outs for things like \\\"except if the user providing\\nthe code is trusted/superuser\\\"? Seems like that would be necessary for\\nthe function to be able to do more-or-less anything, but then I worry\\nthat there's superuser-owned code which could leak information or be\\nused by a malicious owner as that code would still be running as the\\ninvoking user.. Perhaps we could say that the function also has to be\\nleakproof, but that isn't quite the same issue and therefore it seems\\nlike we'd need to decorate all of the functions with another flag that's\\nallowed to be run in this manner.\\n\\nRandom thought- what if the function has a NOTIFY in it with a payload\\nof some kind of sensitive information?\\n\\n> > Unless the trusted roles defaults to '*', then I think it will still\\n> > break some things.\\n> \\n> Definitely. IMHO, it's OK to break some things, certainly in a major\\n> release and maybe even in a minor release. But we don't want to break\\n> more things that we really need to break. And as you say, we want the\\n> restrictions to be comprehensible.\\n\\nReally hard to say if whatever this is is OK for back-patching and\\nbreaking minor releases without knowing exactly what is getting broken\\n... but it'd have to be a very clear edge case of what gets broken for\\nit to be sensible for breaking in a minor release without a very clear\\nvulnerability or such that's being fixed with a simple work-around.\\nJust making all auditing triggers break in a minor release certainly\\nwouldn't be acceptable, as an example that I imagine we all agree with.\\n\\n> > Each of these ideas and sub-ideas affect the semantics, and should be\\n> > documented. But how do we document that some code runs as you, some as\\n> > the person who wrote it, sometimes we obey SECURITY INVOKER and\\n> > sometimes we ignore it and use DEFINER semantics, some code is outside\\n> > a function and always executes as the invoker, some code has some\\n> > security flags, and some code has more security flags, code can change\\n> > between the time you look at it and the time it runs, and it's all\\n> > filtered through GUCs with their own privilege sub-language?\\n> >\\n> > OK, let's assume that we have all of that documented, then how do we\\n> > guide users on what reasonable best practices are for the GUC settings,\\n> > etc.? Or do we just say \\\"this is mechanically how all these parts work,\\n> > good luck assembling it into a secure system!\\\". [ Note: I feel like\\n> > this is the state we are in now. Even if technically we don't have live\\n> > security bugs that I'm aware of, we are setting users up for security\\n> > problems. ]\\n> >\\n> > On the other hand, if we focus on executing code as the user who wrote\\n> > it in most places, then the documentation will be something like: \\\"you\\n> > defined the table, you wrote the code, it runs as you, here are some\\n> > best practices for writing secure code\\\". And we have some different\\n> > documentation for writing a cool SECURITY INVOKER function and how to\\n> > get other users to trust you enough to run it. That sounds a LOT more\\n> > understandable for users.\\n> \\n> What I was imagining is that we would document something like: A table\\n> can have executable code associated with it in a variety of ways. For\\n> example, it can have triggers, default expressions, check constraints,\\n> or row-level security filters. In most cases, these expressions are\\n> executed with the privileges of the user performing the operation on\\n> the table, except when SECURITY DEFINER functions are used. Because\\n> these expressions are set by the table owner and executed by the users\\n> accessing the table, there is a risk that the table owner could\\n> include malicious code that usurps the privileges of the user\\n> accessing the table. For this reason, these expressions are, by\\n> default, restricted from doing <things>. If you want to allow those\\n> operations, you can <something>.\\n\\nWell, one possible answer to 'something' might be 'use SECURITY DEFINER\\nfunctions which are owned by a role allowed to do <things>'. Note that\\nthat doesn't have to be the table owner though, it could be a much more\\nconstrained role. That approach would allow us to leverage the existing\\nGRANT/RLS/et al system for what's allowed and avoid having to create new\\nthings like a complex permission system inside of a GUC for users to\\nhave to understand.\\n\\n> I agree that running code as the table owner is helpful in a bunch of\\n> scenarios, but I also don't think it fixes everything. You earlier\\n> mentioned that switching to the table owner seems to be just a way of\\n> turning SECURITY INVOKER into SECURITY DEFINER in random places, or\\n> maybe that's not exactly what you said but that's what I took from it.\\n> And I think that's right. If we just slather user context switches\\n> everywhere, I'm not actually very sure that's going to be\\n> comprehensible behavior: if my trigger function is SECURITY INVOKER,\\n> why is it getting executed as me, not the inserting user? I also think\\n> there are plenty of cases where that could just replace the current\\n> set of security problems with a new set of security problems. If the\\n> trigger function is SECURITY INVOKER, then the user who wrote it\\n> doesn't have to worry about securing it against attacks by users\\n> accessing the table; it's just running with the permissions of the\\n> user performing the DML. Maybe there are correctness issues if you\\n> don't lock down search_path etc., but there's no security compromise\\n> because there's no user ID switching. As soon as you magically turn\\n> that into a SECURITY DEFINER function, you've provided a way for the\\n> users performing DML to attack the table owner.\\n\\nI agree that we don't want to just turn \\\"SECURITY INVOKER function when\\nrun as a trigger\\\" into SECURITY DEFINER, and that SECURITY DEFINER\\nfunctions need to be able to be written in a mannor that limits the risk\\nof them being able to be abused to gain control of the role which owns\\nthe function (the latter being something we've worked on but should\\ncertainly continue to improve on, independently of any of this..).\\n\\nAlong the same general vein of \\\"don't break things\\\", perhaps an approach\\nwould be a GUC that users can enable that says \\\"don't allow code that\\ndoes something dangerous (again, need to figure out how to do that..)\\nwhen it's written by someone else to run with my privileges (and\\ntherefore isn't a SECURITY DEFINER function)\\\". The idea here being that\\nwe want to encourage users to enable that, maybe we eventually enable it\\nby default in a new major version, and push people in the direction of\\nwriting secure SECURITY DEFINER functions for the cases where they\\nactually need the trigger, or such, to do something beyond whatever we\\ndefine as being 'safe'. This keeps the GUC as a simple on/off or enum\\nlike row_security, fails the action when something not-safe is being\\nattempted, and gives the flexibility of our existing GRANT/RLS system\\nfor the case where a SECURITY DEFINER function is created to perform the\\noperation. This does still need some supporting functions like 'calling\\nrole' or such because there could be many many roles doing an INSERT\\ninto a table which runs a trigger and that trigger runs as some other\\nrole, but the other role could be one that has more privileges than the\\nINSERT'ing role and therefore it needs to implement additional checks on\\nthe operation to limit what the INSERT'ing role is allowed to do.\\n\\nI do worry about asking function authors to effectively rewrite these\\nkinds of permission checks and wonder if there's a way we could make it\\neasier for them- perhaps a kind of function that's SECURITY DEFINER in\\nthat it runs as the owner of the function, but it sets a flag saying\\n\\\"only allow things that the function owner is allowed to do AND the\\ncalling user is allowed to do\\\", similar to the 'intersection of\\nprivileges' idea mentioned elsewhere on this thread.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Wed, 1 Mar 2023 10:48:22 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 1, 2023 at 10:48 AM Stephen Frost <sfrost@snowman.net> wrote:\\n> > Yeah, or any other expressions. Basically impose restrictions when the\\n> > user running the code is not the same as the user who provided the\\n> > code.\\n>\\n> Would this have carve-outs for things like \\\"except if the user providing\\n> the code is trusted/superuser\\\"? Seems like that would be necessary for\\n> the function to be able to do more-or-less anything, but then I worry\\n> that there's superuser-owned code which could leak information or be\\n> used by a malicious owner as that code would still be running as the\\n> invoking user.. Perhaps we could say that the function also has to be\\n> leakproof, but that isn't quite the same issue and therefore it seems\\n> like we'd need to decorate all of the functions with another flag that's\\n> allowed to be run in this manner.\\n\\nYes, I think there can be carve-outs based on the relationship of the\\nusers involved -- if the user who provided the code is the superuser\\nor some other user who can anyway run whatever they want as the user\\nperforming the operation, then there's no point in imposing any\\nrestrictions -- and I think there can also be some way of setting\\npolicy. I proposed a GUC in an earlier email, and you proposed one\\nwith somewhat different semantics in this email, and I'm not sure that\\neither of those things in particular is right or that we ought to be\\nusing a GUC for this at all. However, there should almost certainly be\\nSOME way for the superuser to turn any new restrictions off, and there\\nshould probably also be some way for an unprivileged user to say \\\"you\\nknow, I am totally OK with running any code that alice provides --\\njust go with it.\\\"\\n\\nI don't think we're at a point where we can conclude on what those\\nmechanisms should look like just yet, but I think that everyone who\\nhas spoken up agrees that they ought to exist, assuming we go in this\\ndirection at all.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Mar 2023 12:33:10 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-03-01 at 10:05 -0500, Robert Haas wrote:\\n> For this reason, these expressions are, by\\n> default, restricted from doing <things>.\\n\\nThe hard part is defining <things> without resorting to a bunch of\\nspecial cases, and also in a way that doesn't break a bunch of stuff.\\n\\n> You earlier\\n> mentioned that switching to the table owner seems to be just a way of\\n> turning SECURITY INVOKER into SECURITY DEFINER in random places, or\\n> maybe that's not exactly what you said but that's what I took from\\n> it.\\n\\nYeah, though I glossed over some details, see below.\\n\\n> If we just slather user context switches\\n> everywhere, I'm not actually very sure that's going to be\\n> comprehensible behavior: if my trigger function is SECURITY INVOKER,\\n> why is it getting executed as me, not the inserting user?\\n\\nLet's consider other expressions first. The proposal is that all\\nexpressions attached to a table should run as the table owner (set\\naside compatibility concerns for a moment). If those expressions call a\\nSECURITY INVOKER function, the invoker would need to be the table owner\\nas well. Users could get confused by that, but I think it's\\ndocumentable and understandable; and it's really the only thing that\\nmakes sense -- otherwise changing the user is completely useless.\\n\\nWe should consider triggers as just another expression being executed,\\nand the invoker is the table owner. The problem is that it's a little\\nannoying to users because they probably defined the function for the\\nsole purpose of being a trigger function for a single table, and it\\nmight look as though the SECURITY INVOKER label was ignored.\\n\\nBut there is a difference, which I glossed over before: SECURITY\\nINVOKER on a trigger function would still have significance, because\\nthe function owner (definer) and table owner (invoker) could still be\\ndifferent in the case of a trigger, just like in an expression.\\n\\nThis goes back to my point that SECURITY INVOKER is more complex for us\\nto document and for users to understand. The user *must* understand who\\nthe invoker is in various contexts. That's the situation today and\\nthere's no escaping it. We aren't making things any worse, at least as\\nlong as we can sort out compatibility in a reasonable way.\\n\\n(Aside: I'm having some serious concerns about how the invoker of a\\nfunction called in a view is not the view definer. That's another thing\\nwe'll need to fix, because it's another way of putting SECURITY INVOKER\\ncode in front of someone without them knowing.)\\n\\n(Aside: We should take a second look at the security invoker views\\nbefore we release them. I know that I learned some things during this\\ndiscussion and a fresh look might be useful.)\\n\\n> As soon as you magically turn\\n> that into a SECURITY DEFINER function, you've provided a way for the\\n> users performing DML to attack the table owner.\\n\\nI don't think it's magic, as I said above. But I assume that your more\\ngeneral point is that if we take some responsibility away from the\\ninvoker and place it on the definer, then it creates room for new kinds\\nof problems. And I agree.\\n\\nThe point of moving responsibility to the definer is that the definer\\ncan actually do something to protect themselves (nail down search_path,\\nrestrict USAGE privs, and avoid dynamic SQL); whereas the invoker is\\nnearly helpless.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 01 Mar 2023 10:13:55 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 1, 2023 at 1:13 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> I don't think it's magic, as I said above. But I assume that your more\\n> general point is that if we take some responsibility away from the\\n> invoker and place it on the definer, then it creates room for new kinds\\n> of problems. And I agree.\\n>\\n> The point of moving responsibility to the definer is that the definer\\n> can actually do something to protect themselves (nail down search_path,\\n> restrict USAGE privs, and avoid dynamic SQL); whereas the invoker is\\n> nearly helpless.\\n\\nI think there's some truth to that allegation, but I think it largely\\ncomes from the fact that we've given very little thought or attention\\nto this problem. We have a section in the documentation on writing\\nSECURITY DEFINER functions safely because we've known for a long time\\nthat it's dangerous and we've provided some (imperfect) tools for\\ndealing with it, like allowing a SET search_path clause to be attached\\nto a function definition. We have no comparable documentation section\\nabout SECURITY INVOKER because we haven't historically taken that\\nseriously as a security hazard and we have no tools to make it safe.\\nBut we could, as with what I'm proposing here, or the user/function\\ntrust mechanism previously proposed by Noah, or various other ideas\\nthat we might have.\\n\\nI don't like the idea of saying that we're not going to try to invent\\nanything new and just push people into using the stuff we already\\nhave. The stuff we have for security SECURITY DEFINER functions is not\\nvery good. True, it's better than what we have for protecting against\\nthe risks inherent in SECURITY INVOKER, but that's not saying much:\\nanything at all is better than nothing. But it's easy to forget a SET\\nsearch_path clause on one of your functions, or to include something\\nin that search path that's not actually safe, or to have a problem\\nthat isn't blocked by just setting search_path. Also, not that it's\\nthe most important consideration here, but putting a SET clause on\\nyour functions is really kind of expensive if what the function does\\nis trivial, which if you're using it in an index expression or a\\ndefault expression, will often be the case. I don't want to pretend\\nlike I have all the answers here, but I find it really hard to believe\\nthat pushing people to do the same kind of nonsense that's currently\\nrequired when writing a SECURITY DEFINER function for a lot of their\\nother functions as well is going to be a win. I think it will probably\\nsuck.\\n\\nTo be fair, it's possible that there's no solution to this class of\\nproblems that *doesn't* suck, but I think we should look a lot harder\\nbefore coming to that conclusion. I've come to agree with your\\ncontention that we're not taking the hazards of SECURITY INVOKER\\nnearly seriously enough, but I think you're underestimating the\\nhazards that SECURITY DEFINER poses, and overestimating how easy it is\\nto avoid them.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Mar 2023 16:06:14 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-03-01 at 16:06 -0500, Robert Haas wrote:\\n\\n> To be fair, it's possible that there's no solution to this class of\\n> problems that *doesn't* suck, but I think we should look a lot harder\\n> before coming to that conclusion.\\n\\nFair enough. The situation is bad enough that I'm willing to consider a\\npretty wide range of solutions and mitigations that might otherwise be\\nunappealing.\\n\\nI think there might be something promising in your idea to highly\\nrestrict the privileges of code attached to a table. A lot of\\nexpressions are really simple and don't need much to be both useful and\\nsafe. We may not need the exact same solution for both default\\nexpressions and triggers. Some details to work through, though.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 01 Mar 2023 14:27:25 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-28 12:36:38 -0800, Jeff Davis wrote:\\n> On Tue, 2023-02-28 at 11:28 -0800, Andres Freund wrote:\\n> > I can only repeat myself in stating that SECURITY DEFINER solves none\\n> > of the\\n> > relevant issues. I included several examples of why it doesn't in the\\n> > recent\\n> > thread about \\\"blocking SECURITY INVOKER\\\". E.g. that default arguments\\n> > of\\n> > SECDEF functions are evaluated with the current user's privileges,\\n> > not the\\n> > function owner's privs:\\n> > \\n> > https://postgr.es/m/20230113032943.iyxdu7bnxe4cmbld%40awork3.anarazel.de\\n> \\n> I was speaking a bit loosely, using \\\"SECURITY DEFINER\\\" to mean the\\n> semantics of executing code as the one who wrote it. I didn't\\n> specifically mean the function marker, because as you pointed out in\\n> the other thread, that's not enough.\\n\\nOh, ok.\\n\\n\\n> From your email it looks like there is still a path forward:\\n> \\n> \\\"The proposal to not trust any expressions controlled by untrusted\\n> users at least allows to prevent execution of code, even if it doesn't\\n> provide a way to execute the code in a safe manner. Given that we\\n> don't have the former, it seems foolish to shoot for the latter.\\\"\\n> \\n> And later:\\n> \\n> \\\"I think the combination of\\n> a) a setting that restricts evaluation of any non-trusted expressions,\\n> independent of the origin\\n> b) an easy way to execute arbitrary statements within\\n> SECURITY_RESTRICTED_OPERATION\\\"\\n> \\n> My takeaway from that thread was that we need a mechanism to deal with\\n> non-function code (e.g. default expressions) first; but once we have\\n> that, it opens up the design space to better solutions or at least\\n> mitigations. Is that right?\\n\\nI doubt it's realistic to change the user for all kinds of expressions\\nindividually. A query can involve expressions controlled by many users,\\nchanging the current user in a super granular way seems undesirable from a\\nperformance and complexity pov.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Mar 2023 16:14:30 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-28 08:37:02 -0500, Robert Haas wrote:\\n> On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > > Yeah. That's the idea I was floating, at least.\\n> >\\n> > Isn't that a hard problem; maybe impossible?\\n>\\n> It doesn't seem that hard to me; maybe I'm missing something.\\n>\\n> The existing SECURITY_RESTRICTED_OPERATION flag basically prevents you\\n> from tinkering with the session state. If we also had a similar flags\\n> like DATABASE_READS_PROHIBITED and DATABASE_WRITES_PROHIBITED (or just\\n> a combined DATABASE_ACCESS_PROHIBITED flag) I think that would be\\n> pretty close to what we need. The idea would be that, when a user\\n> executes a function or procedure owned by a user that they don't trust\\n> completely, we'd set\\n> SECURITY_RESTRICTED_OPERATION|DATABASE_READS_PROHIBITED|DATABASE_WRITES_PROHIBITED.\\n> And we could provide a user with a way to express the degree of trust\\n> they have in some other user or perhaps even some specific function,\\n> e.g.\\n\\nISTM that this would require annotating most functions in the system. There's\\nmany problems besides accessing database contents. Just a few examples:\\n\\n- dblink functions to access another system / looping back\\n- pg_read_file()/pg_file_write() allows almost arbitrary mischief\\n- pg_stat_reset[_shared]()\\n- creating/dropping logical replication slots\\n- use untrusted PL functions\\n- many more\\n\\nA single wrongly annotated function would be sufficient to escape. This\\nincludes user defined functions.\\n\\n\\nThis basically proposes that we can implement a safe sandbox for executing\\narbitrary code in a privileged context. IMO history suggests that that's a\\nhard thing to do.\\n\\nAm I missing something?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 1 Mar 2023 16:34:40 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 1, 2023 at 7:34 PM Andres Freund <andres@anarazel.de> wrote:\\n> ISTM that this would require annotating most functions in the system. There's\\n> many problems besides accessing database contents. Just a few examples:\\n>\\n> - dblink functions to access another system / looping back\\n> - pg_read_file()/pg_file_write() allows almost arbitrary mischief\\n> - pg_stat_reset[_shared]()\\n> - creating/dropping logical replication slots\\n> - use untrusted PL functions\\n> - many more\\n>\\n> A single wrongly annotated function would be sufficient to escape. This\\n> includes user defined functions.\\n>\\n> This basically proposes that we can implement a safe sandbox for executing\\n> arbitrary code in a privileged context. IMO history suggests that that's a\\n> hard thing to do.\\n\\nYeah, that's true, but I don't think switching users all the time is\\ngoing to be great either. And it's not like other people haven't gone\\nthis way: that's what plperl (not plperlu) is all about, and\\nJavaScript running in your browser, and so on. Those things aren't\\nproblem-free, of course, but we're all using them.\\n\\nWhen I was initially thinking about this, I thought that maybe we\\ncould just block access to tables and utility statements. That's got\\nproblems in both directions. On the one hand, there are functions like\\nthe ones you propose here that have side effects which we might not\\nwant to allow, and on the other hand, somebody might have an index\\nexpression that does a lookup in a table that they \\\"never change\\\". The\\nlatter case is problematic for non-security reasons, because there's\\nan invisible dump-ordering constraint that must be obeyed for\\ndump/restore to work at all, but there's no security issue. Still, I'm\\nnot sure this idea is completely dead in the water. It doesn't seem\\nunreasonable to me that if you have that kind of case, you have to\\nsomehow opt into the behavior: yeah, I know that index functions I'm\\nexecuting are going to read from tables, and I consent to that. And\\nsimilarly, if your index expression calls pg_stat_reset_shared(), that\\nprobably ought to be blocked by default too, and if you want to allow\\nit, you have to say so. Yes, that does require labelling functions, or\\nmaybe putting run-time checks in them:\\n\\nRequireAvailableCapability(CAP_MODIFY_DATABASE_STATE);\\n\\nIf that capability isn't available in the present context, the call\\nerrors out. That way, it's possible for the required capabilities to\\ndepend on the arguments to the function, and we can change markings in\\nminor releases without needing catalog changes.\\n\\nThere's another way of thinking about this problem, which involves\\nsupposing that the invoker should only be induced to do things that\\nthe definer could also have done. Basically do every privilege check\\ntwice, and require that both pass. The problem I have with that is\\nthat there are various operations which depend on your identity, not\\njust your privileges. For instance, a GRANT statement records a\\ngrantor, and a REVOKE statement infers a grantor whose grant is to be\\nrevoked. The operation isn't just allowed or disallowed based on who\\nperformed it -- it actually does something different depending on who\\nperforms it. I believe we have a number of cases like that, and I\\nthink that they suggest that that whole model is pretty flawed. Even\\nif that were no issue, this also seems extremely complex to implement,\\nbecause we have an absolute crap-ton of places that perform privilege\\nchecks and getting all of those places to check privileges as a second\\nuser seems nightmarish. I also think that it might be lead to\\nconfusing error messages: alice tried to do X but we're not allowing\\nit because bob isn't allowed to do X. Eh, what? As opposed to the\\nsandboxing approach, where I think you get something more like:\\n\\nERROR: database state cannot be modified now\\nDETAIL: The database system is evaluating an index expression.\\nHINT: Do $SOMETHING to allow this.\\n\\nI don't want to press too hard on my idea here. I'm sure it has a\\nbunch of problems apart from those already mentioned, and those\\nalready mentioned are not trivial. However, I do think there might be\\nways to make it work, and I'm not at all convinced that trying to\\nswitch users all over the place is going to be be better, either for\\nsecurity or usability. Is there some other whole kind of approach we\\ncan take here that we haven't discussed yet?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Mar 2023 09:43:21 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Feb 9, 2023 at 4:46 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> On 2/6/23 08:22, Robert Haas wrote:\\n> > I don't think that's quite the right concept. It seems to me that the\\n> > client is responsible for informing the server of what the situation\\n> > is, and the server is responsible for deciding whether to allow the\\n> > connection. In your scenario, the client is not only communicating\\n> > information (\\\"here's the password I have got\\\") but also making demands\\n> > on the server (\\\"DO NOT authenticate using anything else\\\"). I like the\\n> > first part fine, but not the second part.\\n>\\n> For what it's worth, making a negative demand during authentication is\\n> pretty standard: if you visit example.com and it tells you \\\"I need your\\n> OS login password and Social Security Number to authenticate you,\\\" you\\n> have the option of saying \\\"no thanks\\\" and closing the tab.\\n\\nNo, that's the opposite, and exactly the point I'm trying to make. In\\nthat case, the SERVER says what it's willing to accept, and the CLIENT\\ndecides whether or not to provide that. In your proposal, the client\\ntells the server which authentication methods to accept.\\n\\n> In a hypothetical world where the server presented the client with a\\n> list of authentication options before allowing any access, this would\\n> maybe be a little less convoluted to solve. For example, a proxy seeing\\n> a SASL list of\\n>\\n> - ANONYMOUS\\n> - EXTERNAL\\n>\\n> could understand that both methods allow the client to assume the\\n> authority of the proxy itself. So if its client isn't allowed to do\\n> that, the proxy realizes something is wrong (either it, or its target\\n> server, has been misconfigured or is under attack), and it can close the\\n> connection *before* the server runs login triggers.\\n\\nYep, that totally makes sense to me, but I don't think it's what you proposed.\\n\\n> This sounds like a reasonable separation of responsibilities on the\\n> surface, but I think it's subtly off. The entire confused-deputy problem\\n> space revolves around the proxy being unable to correctly decide which\\n> connections to allow unless it also knows why the connections are being\\n> authorized.\\n\\nI agree.\\n\\n> You've constructed an example where that's not a concern: everything's\\n> symmetrical, all proxies operate with the same authority, and internal\\n> users are identical to external users. But the CVE that led to the\\n> password requirement, as far as I can tell, dealt with asymmetry. The\\n> proxy had the authority to connect locally to a user, and the clients\\n> had the authority to connect to other machines' users, but those users\\n> weren't the same and were not mutually trusting.\\n\\nYeah, agreed. So, I think the point here is that the proxy\\nconfiguration (and pg_hba.conf) need to be sufficiently powerful that\\neach user can permit the things that make sense in their environment\\nand block the things that don't.\\n\\nI don't think we're really very far apart here, but for some reason\\nthe terminology seems to be giving us some trouble. Of course, there's\\nalso the small problem of actually finding the time to do some\\nmeaningful work on this stuff, rather than just talking....\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Mar 2023 14:04:14 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 7, 2023 at 11:04 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Thu, Feb 9, 2023 at 4:46 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > On 2/6/23 08:22, Robert Haas wrote:\\n> > > I don't think that's quite the right concept. It seems to me that the\\n> > > client is responsible for informing the server of what the situation\\n> > > is, and the server is responsible for deciding whether to allow the\\n> > > connection. In your scenario, the client is not only communicating\\n> > > information (\\\"here's the password I have got\\\") but also making demands\\n> > > on the server (\\\"DO NOT authenticate using anything else\\\"). I like the\\n> > > first part fine, but not the second part.\\n> >\\n> > For what it's worth, making a negative demand during authentication is\\n> > pretty standard: if you visit example.com and it tells you \\\"I need your\\n> > OS login password and Social Security Number to authenticate you,\\\" you\\n> > have the option of saying \\\"no thanks\\\" and closing the tab.\\n>\\n> No, that's the opposite, and exactly the point I'm trying to make. In\\n> that case, the SERVER says what it's willing to accept, and the CLIENT\\n> decides whether or not to provide that. In your proposal, the client\\n> tells the server which authentication methods to accept.\\n\\nAh, that's a (the?) sticking point. In my example, the client doesn't\\ntell the server which methods to accept. The client tells the server\\nwhich method the *client* has the ability to use. (Or, implicitly,\\nwhich methods it refuses to use.)\\n\\nThat shouldn't lose any power, security-wise, because the server is\\nlooking for an intersection of the two sets. And the client already\\nhas the power to do that for almost every form of authentication,\\nexcept the ambient methods.\\n\\nI don't think I necessarily like that option better than SASL-style,\\nbut hopefully that clarifies it somewhat?\\n\\n> I don't think we're really very far apart here, but for some reason\\n> the terminology seems to be giving us some trouble.\\n\\nAgreed.\\n\\n> Of course, there's\\n> also the small problem of actually finding the time to do some\\n> meaningful work on this stuff, rather than just talking....\\n\\nAgreed :)\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Wed, 8 Mar 2023 11:30:15 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > No, that's the opposite, and exactly the point I'm trying to make. In\\n> > that case, the SERVER says what it's willing to accept, and the CLIENT\\n> > decides whether or not to provide that. In your proposal, the client\\n> > tells the server which authentication methods to accept.\\n>\\n> Ah, that's a (the?) sticking point. In my example, the client doesn't\\n> tell the server which methods to accept. The client tells the server\\n> which method the *client* has the ability to use. (Or, implicitly,\\n> which methods it refuses to use.)\\n>\\n> That shouldn't lose any power, security-wise, because the server is\\n> looking for an intersection of the two sets. And the client already\\n> has the power to do that for almost every form of authentication,\\n> except the ambient methods.\\n>\\n> I don't think I necessarily like that option better than SASL-style,\\n> but hopefully that clarifies it somewhat?\\n\\nHmm, yeah, I guess that's OK. I still don't love it, though. It feels\\nmore solid to me if the proxy can actually block the connections\\nbefore they even happen, without having to rely on a server\\ninteraction to figure out what is permissible.\\n\\nI don't know what you mean by SASL-style, exactly.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 8 Mar 2023 14:40:42 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-02-07 16:56:55 -0500, Robert Haas wrote:\\n> On Wed, Feb 1, 2023 at 4:02 PM Andres Freund <andres@anarazel.de> wrote:\\n> > > + /* Is the use of a password mandatory? */\\n> > > + must_use_password = MySubscription->passwordrequired &&\\n> > > + !superuser_arg(MySubscription->owner);\\n> >\\n> > There's a few repetitions of this - perhaps worth putting into a helper?\\n> \\n> I don't think so. It's slightly different each time, because it's\\n> pulling data out of different data structures.\\n> \\n> > This still leaks the connection on error, no?\\n> \\n> I've attempted to fix this in v4, attached.\\n\\nHm - it still feels wrong that we error out in case of failure, despite the\\ncomment to the function saying:\\n * Returns NULL on error and fills the err with palloc'ed error message.\\n\\nOther than this, the change looks ready to me.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 8 Mar 2023 11:47:43 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 8, 2023 at 11:40 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > I don't think I necessarily like that option better than SASL-style,\\n> > but hopefully that clarifies it somewhat?\\n>\\n> Hmm, yeah, I guess that's OK.\\n\\nOkay, cool.\\n\\n> I still don't love it, though. It feels\\n> more solid to me if the proxy can actually block the connections\\n> before they even happen, without having to rely on a server\\n> interaction to figure out what is permissible.\\n\\nSure. I don't see a way for the proxy to figure that out by itself,\\nthough, going back to my asymmetry argument from before. Only the\\nserver truly knows, at time of HBA processing, whether the proxy\\nitself has authority. If the proxy knew, it wouldn't be confused.\\n\\n> I don't know what you mean by SASL-style, exactly.\\n\\nThat's the one where the server explicitly names all forms of\\nauthentication, including the ambient ones (ANONYMOUS, EXTERNAL,\\netc.), and requires the client to choose one before running any\\nactions on their behalf. That lets the require_auth machinery work for\\nthis case, too.\\n\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Wed, 8 Mar 2023 14:44:26 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 8, 2023 at 5:44 PM Jacob Champion <jchampion@timescale.com> wrote:\\n>\\n> On Wed, Mar 8, 2023 at 11:40 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> > > I don't think I necessarily like that option better than SASL-style,\\n> > > but hopefully that clarifies it somewhat?\\n> >\\n> > Hmm, yeah, I guess that's OK.\\n>\\n> Okay, cool.\\n>\\n> > I still don't love it, though. It feels\\n> > more solid to me if the proxy can actually block the connections\\n> > before they even happen, without having to rely on a server\\n> > interaction to figure out what is permissible.\\n>\\n> Sure. I don't see a way for the proxy to figure that out by itself,\\n> though, going back to my asymmetry argument from before. Only the\\n> server truly knows, at time of HBA processing, whether the proxy\\n> itself has authority. If the proxy knew, it wouldn't be confused.\\n>\\n> > I don't know what you mean by SASL-style, exactly.\\n>\\n> That's the one where the server explicitly names all forms of\\n> authentication, including the ambient ones (ANONYMOUS, EXTERNAL,\\n> etc.), and requires the client to choose one before running any\\n> actions on their behalf. That lets the require_auth machinery work for\\n> this case, too.\\n>\\n> --Jacob\\n\\n\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Mar 2023 09:12:37 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 8, 2023 at 5:44 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> Sure. I don't see a way for the proxy to figure that out by itself,\\n> though, going back to my asymmetry argument from before. Only the\\n> server truly knows, at time of HBA processing, whether the proxy\\n> itself has authority. If the proxy knew, it wouldn't be confused.\\n\\nThat seems like a circular argument. If you call the problem the\\nconfused deputy problem then the issue must indeed be that the deputy\\nis confused, and needs to talk to someone else to get un-confused. But\\nwhy is the deputy necessarily confused in the first place? Our deputy\\nis confused because our code to decide whether to proxy a connection\\nor not is super-dumb, but if there's an intrinsic reason it can't be\\nsmarter, I don't understand what it is.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Mar 2023 09:17:01 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 9, 2023 at 6:17 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> That seems like a circular argument. If you call the problem the\\n> confused deputy problem then the issue must indeed be that the deputy\\n> is confused, and needs to talk to someone else to get un-confused. But\\n> why is the deputy necessarily confused in the first place? Our deputy\\n> is confused because our code to decide whether to proxy a connection\\n> or not is super-dumb,\\n\\nNo, I think our proxy is confused because it doesn't know what power\\nit has, and it can't tell the server what power it wants to use. That\\nproblem is independent of the decision to proxy. You're suggesting\\nstrengthening the code that makes that decision -- adding an oracle\\n(in the form of a DBA) that knows about the confusion and actively\\nmitigates it. That's guaranteed to work if the oracle is perfect,\\nbecause \\\"perfect\\\" is somewhat tautologically defined as \\\"whatever\\nensures secure operation\\\". But the oracle doesn't reduce the\\nconfusion, and DBAs aren't perfect.\\n\\nIf you want to add a Sheriff Andy to hold Barney Fife's hand [1], that\\nwill absolutely make Barney less of a problem, and I'd like to have\\nAndy around regardless. But Barney still doesn't know what's going on,\\nand when Andy makes a mistake, there will still be trouble. I'd like\\nto teach Barney some useful stuff.\\n\\n> but if there's an intrinsic reason it can't be\\n> smarter, I don't understand what it is.\\n\\nWell... I'm not well-versed enough in this to prove non-existence of a\\nsolution. Can you find a solution, using the current protocol, that\\ndoesn't make use of perfect out-of-band knowledge? We have a client\\nthat will authenticate using any method the server asks it to, even if\\nits user intended to use something else. And we have a server that can\\neagerly skip client authentication, and then eagerly run code on its\\nbehalf, without first asking the client what it's even trying to do.\\nThat would be an inherently hostile environment for *any* proxy, not\\njust ours.\\n\\nThanks,\\n--Jacob\\n\\n[1] https://en.wikipedia.org/wiki/The_Andy_Griffith_Show#Premise_and_characters\\n\\n\\n\",\n \"msg_date\": \"Fri, 10 Mar 2023 16:00:19 -0800\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 10, 2023 at 7:00 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> On Thu, Mar 9, 2023 at 6:17 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > That seems like a circular argument. If you call the problem the\\n> > confused deputy problem then the issue must indeed be that the deputy\\n> > is confused, and needs to talk to someone else to get un-confused. But\\n> > why is the deputy necessarily confused in the first place? Our deputy\\n> > is confused because our code to decide whether to proxy a connection\\n> > or not is super-dumb,\\n>\\n> No, I think our proxy is confused because it doesn't know what power\\n> it has, and it can't tell the server what power it wants to use. That\\n> problem is independent of the decision to proxy. You're suggesting\\n> strengthening the code that makes that decision -- adding an oracle\\n> (in the form of a DBA) that knows about the confusion and actively\\n> mitigates it. That's guaranteed to work if the oracle is perfect,\\n> because \\\"perfect\\\" is somewhat tautologically defined as \\\"whatever\\n> ensures secure operation\\\". But the oracle doesn't reduce the\\n> confusion, and DBAs aren't perfect.\\n\\nI think this is the root of our disagreement. My understanding of the\\nprevious discussion is that people think that the major problem here\\nis the wraparound-to-superuser attack. That is, in general, we expect\\nthat when we connect to a database over the network, we expect it to\\ndo some kind of active authentication, like asking us for a password,\\nor asking us for an SSL certificate that isn't just lying around for\\nanyone to use. However, in the specific case of a local connection, we\\nhave a reliable way of knowing who the remote user is without any kind\\nof active authentication, namely 'peer' authentication or perhaps even\\n'trust' if we trust all the local users, and so we don't judge it\\nunreasonable to allow local connections without any form of active\\nauthentication. There can be some scenarios where even over a network\\nwe can know the identity of the person connecting with complete\\ncertainty, e.g. if endpoints are locked down such that the source IP\\naddress is a reliable indicator of who is initiating the connection,\\nbut in general when there's a network involved you don't know who the\\nperson making the connection is and need to do something extra to\\nfigure it out.\\n\\nIf you accept this characterization of the problem, then I don't think\\nthe oracle is that hard to design. We simply set it up not to allow\\nwraparound connections, or maybe even more narrowly to not allow\\nwraparound connections to superuser. If the DBA has some weird network\\ntopology where that's not the correct rule, either because they want\\nto allow wraparound connections or they want to disallow other things,\\nthen yeah they have to tell us what to allow, but I don't really see\\nwhy that's an unreasonable expectation. I'd expect the correct\\nconfiguration of the proxy facility to fall naturally out of what's\\nallowed in pg_hba.conf. If machine A is configured to accept\\nconnections from machines B and C based on environmental factors, then\\nmachines B and C should be configured not to proxy connections to A.\\nIf machines B and C aren't under our control such that we can\\nconfigure them that way, then the configuration is fundamentally\\ninsecure in a way that we can't really fix.\\n\\nI think that what you're proposing is that B and C can just be allowed\\nto proxy to A and A can say \\\"hey, by the way, I'm just gonna let you\\nin without asking for anything else\\\" and B and C can, when proxying,\\nreact to that by disconnecting before the connection actually goes\\nthrough. That's simpler, in a sense. It doesn't require us to set up\\nthe proxy configuration on B and C in a way that matches what\\npg_hba.conf allows on A. Instead, B and C can automatically deduce\\nwhat connections they should refuse to proxy. I guess that's nice, but\\nit feels pretty magical to me. It encourages the DBA not to think\\nabout what B and C should actually be allowed to proxy, and instead\\njust trust that the automatics are going to prevent any security\\ndisasters. I'm not sure that they always will, and I fear cultivating\\ntoo much reliance on them. I think that if you're setting up a network\\ntopology where the correct rule is something more complex than \\\"don't\\nallow wraparound connections to superuser,\\\" maybe you ought to be\\nforced to spell that rule out instead of letting the system deduce one\\nthat you hope will be right.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 20 Mar 2023 12:32:00 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 8, 2023 at 2:47 PM Andres Freund <andres@anarazel.de> wrote:\\n> Hm - it still feels wrong that we error out in case of failure, despite the\\n> comment to the function saying:\\n> * Returns NULL on error and fills the err with palloc'ed error message.\\n\\nI've amended the comment so that it explains why it's done that way.\\n\\n> Other than this, the change looks ready to me.\\n\\nWell, it still needed documentation changes and pg_dump changes. I've\\nadded those in the attached version.\\n\\nIf nobody's too unhappy with the idea, I plan to commit this soon,\\nboth because I think that the feature is useful, and also because I\\nthink it's an important security improvement. Since replication is\\ncurrently run as the subscription owner, any table owner can\\ncompromise the subscription owner's account, which is really bad, but\\nif the subscription owner can be a non-superuser, it's a little bit\\nless bad. From a security point of view, I think the right thing to do\\nand what would improve security a lot more is to run replication as\\nthe table owner rather than the subscription owner. I've posted a\\npatch for that at\\nhttp://postgr.es/m/CA+TgmoaSCkg9ww9oppPqqs+9RVqCexYCE6Aq=UsYPfnOoDeFkw@mail.gmail.com\\nand AFAICT everyone agrees with the idea, even if the patch itself\\nhasn't yet attracted any code reviews. But although the two patches\\nare fairly closely related, this seems to be a good idea whether that\\nmoves forward or not, and that seems to be a good idea whether this\\nmoves forward or not. As this one has had more review and discussion,\\nmy current thought is to try to get this one committed first.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 22 Mar 2023 12:16:15 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-03-22 at 12:16 -0400, Robert Haas wrote:\\n> If nobody's too unhappy with the idea, I plan to commit this soon,\\n> both because I think that the feature is useful, and also because I\\n> think it's an important security improvement.\\n\\nIs there any chance I can convince you to separate the privileges of\\nusing a connection string and creating a subscription, as I\\nsuggested[1] earlier?\\n\\nIt would be useful for dblink, and I also plan to propose CREATE\\nSUBSCRIPTION ... SERVER for v17 (it was too late for 16), for which it\\nwould also be useful to make the distinction.\\n\\nYou seemed to generally think it was a reasonable idea, but wanted to\\nwait for the other patch. I think it's the right breakdown of\\nprivileges even now, and I don't see a reason to give ourselves a\\nheadache later trying to split up the privileges later.\\n\\nRegards,\\n\\tJeff Davis\\n\\n[1]\\nhttps://www.postgresql.org/message-id/fa1190c117c2455f2dd968a1a09f796ccef27b29.camel@j-davis.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 22 Mar 2023 12:53:18 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 22, 2023 at 3:53 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> Is there any chance I can convince you to separate the privileges of\\n> using a connection string and creating a subscription, as I\\n> suggested[1] earlier?\\n\\nWhat would this amount to concretely? Also adding a\\npg_connection_string predefined role and requiring both that and\\npg_create_subscription in all cases until your proposed changes get\\nmade?\\n\\nIf so, I don't think that's a good idea. Maybe for some reason your\\nproposed changes won't end up happening, and then we've just got a\\nuseless extra thing that makes things confusing. I think that adding a\\npg_connection_string privilege properly belongs to whatever patch\\nmakes it possible to separate the connection string from the\\nsubscription, and that we probably shouldn't add those even in\\nseparate commits, let alone in separate major releases.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 23 Mar 2023 11:52:18 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-03-23 at 11:52 -0400, Robert Haas wrote:\\n> What would this amount to concretely? Also adding a\\n> pg_connection_string predefined role and requiring both that and\\n> pg_create_subscription [to CREATE SUBSCRIPTION]\\n\\nYes.\\n\\n> If so, I don't think that's a good idea. Maybe for some reason your\\n> proposed changes won't end up happening, and then we've just got a\\n> useless extra thing that makes things confusing.\\n\\nEven if my changes don't happen, I would find it less confusing and\\nmore likely that users understand what they're doing.\\n\\nTo most users, the consequences of allowing users to write connection\\nstrings on the server are far from obvious. Even we, as developers,\\nneeded to spend a lot of time discussing the nuances.\\n\\nSomeone merely granting the ability to CREATE SUBSCRIPTION would read\\nthat page in the docs, which is dominated by the mechanics of a\\nsubscription and says little about the connection string, let alone the\\nsecurity nuances of using it on a server.\\n\\nBut if there is also a separate connection string privilege required,\\nwe can document it better and they are more likely to find it and\\nunderstand.\\n\\nBeyond that, the connection string and the mechanics of the\\nsubscription are really different concepts.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 23 Mar 2023 10:41:05 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 23, 2023 at 1:41 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> Even if my changes don't happen, I would find it less confusing and\\n> more likely that users understand what they're doing.\\n\\nI respectfully but firmly disagree. I think having two predefined\\nroles that are both required to create a subscription and neither of\\nwhich allows you to do anything other than create a subscription is\\nintrinsically confusing. I'm not willing to commit a patch that works\\nlike that, and I will object if someone else wants to do so.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 23 Mar 2023 15:39:31 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wed, 2023-03-22 at 12:16 -0400, Robert Haas wrote:\\n> I've posted a\\n> patch for that at\\n> http://postgr.es/m/CA+TgmoaSCkg9ww9oppPqqs+9RVqCexYCE6Aq=UsYPfnOoDeFkw@mail.gmail.com\\n> and AFAICT everyone agrees with the idea, even if the patch itself\\n> hasn't yet attracted any code reviews. But although the two patches\\n> are fairly closely related, this seems to be a good idea whether that\\n> moves forward or not, and that seems to be a good idea whether this\\n> moves forward or not. As this one has had more review and discussion,\\n> my current thought is to try to get this one committed first.\\n\\nThe current patch (non-superuser-subscriptions) is the most user-facing\\naspect, and it seems wrong to commit it before we have the security\\nmodel in a reasonable place. As you pointed out[1], it's not in a\\nreasonable place now, so encouraging more use seems like a bad idea.\\n\\nThe other patch you posted seems like it makes a lot of progress in\\nthat direction, and I think that should go in first. That was one of\\nthe items I suggested previously[2], so thank you for working on that.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n[1]\\nhttps://www.postgresql.org/message-id/CA%2BTgmoavSQVcvEW3ZgZ7a1Q-TJ-fp0%2BNt7W3D7FCawArtTCBCQ%40mail.gmail.com\\n\\n[2]\\nhttps://www.postgresql.org/message-id/27c557b12a590067c5e00588009447bb5bb2dd42.camel@j-davis.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Mar 2023 00:17:14 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 24, 2023 at 3:17 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> The current patch (non-superuser-subscriptions) is the most user-facing\\n> aspect, and it seems wrong to commit it before we have the security\\n> model in a reasonable place. As you pointed out[1], it's not in a\\n> reasonable place now, so encouraging more use seems like a bad idea.\\n\\nI certainly agree that the security model isn't in a reasonable place\\nright now. However, I feel that:\\n\\n(1) adding an extra predefined role doesn't really help, because it\\ndoesn't actually do anything in and of itself, it only prepares for\\nfuture work, and\\n\\n(2) even adding the connection string security stuff that you're\\nproposing doesn't really help, because (2a) connection string security\\nis almost completely separate from the internal security\\nconsiderations addressed in the message to which you linked, and (2b)\\nin my opinion, there will be a lot of people who won't use that\\nconnection string security stuff even if we had it, possibly even a\\nlarge majority of people won't use it, because it responds to a\\nspecific use case which I think a lot of people don't have, and\\n\\n(3) I don't agree either that this patch would encourage more use of\\nlogical replication or that it would be bad if it did. I mean, there\\ncould be someone who knows about this patch and will hesitate to\\ndeploy logical replication if it doesn't get committed, or maybe\\nslightly more likely, won't be able to do so if this patch doesn't get\\ncommitted because they're running in a cloud environment. But probably\\nnot. Cloud providers are already hacking around this problem,\\nMicrosoft included. As a community, we're better off having a standard\\nsolution in core than having every vendor hack it their own way. And\\noutside of a cloud environment, there's not really any reason for the\\nlack of this patch to make a potential user hesitate. Also, features\\ngetting used is a thing that I think we should all want. If logical\\nreplication is in such a bad state that we think people should be\\nusing it, we should rip it out until the issues are fixed. I don't\\nthink anyone would seriously propose that such a course of action is\\nadvisable. So the alternative is to make it better.\\n\\nTo reiterate what I think the most important point here is, both Azure\\nand AWS already let you do this. EDB's own cloud offering is also\\ngoing to let you do this, whether this change goes in or not. But if\\nthis patch gets committed, then eventually all of those vendors and\\nwhatever others are out there will let you do this in the same way,\\ni.e. pg_create_subscription, instead of every vendor having their own\\npatch to the code that does what this patch does through some method\\nthat is specific to that cloud vendor. That sort of fragmentation of\\nthe ecosystem is not good for anyone, AFAICS.\\n\\n> The other patch you posted seems like it makes a lot of progress in\\n> that direction, and I think that should go in first. That was one of\\n> the items I suggested previously[2], so thank you for working on that.\\n\\nPerhaps you could review that work?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Mar 2023 09:24:54 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 24, 2023 at 9:24 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> > The other patch you posted seems like it makes a lot of progress in\\n> > that direction, and I think that should go in first. That was one of\\n> > the items I suggested previously[2], so thank you for working on that.\\n>\\n> Perhaps you could review that work?\\n\\nAh, you already did. Thanks.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Mar 2023 10:47:08 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 3/20/23 09:32, Robert Haas wrote:\\n> I think this is the root of our disagreement.\\n\\nAgreed.\\n\\n> My understanding of the\\n> previous discussion is that people think that the major problem here\\n> is the wraparound-to-superuser attack. That is, in general, we expect\\n> that when we connect to a database over the network, we expect it to\\n> do some kind of active authentication, like asking us for a password,\\n> or asking us for an SSL certificate that isn't just lying around for\\n> anyone to use. However, in the specific case of a local connection, we\\n> have a reliable way of knowing who the remote user is without any kind\\n> of active authentication, namely 'peer' authentication or perhaps even\\n> 'trust' if we trust all the local users, and so we don't judge it\\n> unreasonable to allow local connections without any form of active\\n> authentication. There can be some scenarios where even over a network\\n> we can know the identity of the person connecting with complete\\n> certainty, e.g. if endpoints are locked down such that the source IP\\n> address is a reliable indicator of who is initiating the connection,\\n> but in general when there's a network involved you don't know who the\\n> person making the connection is and need to do something extra to\\n> figure it out.\\n\\nOkay, but this is walking back from the network example you just\\ndescribed upthread. Do you still consider that in scope, or...?\\n\\n> If you accept this characterization of the problem,\\n\\nI'm not going to say yes or no just yet, because I don't understand your\\nrationale for where to draw the lines.\\n\\nIf you just want the bare minimum thing that will solve the localhost\\ncase, require_auth landed this week. Login triggers are not yet a thing,\\nso `require_auth=password,md5,scram-sha-256` ensures active\\nauthentication. You don't even have to disallow localhost connections,\\nas far as I can tell; they'll work as intended.\\n\\nIf you think login triggers will get in for PG16, my bigger proposal\\ncan't help in time. But if you're drawing the line at \\\"environmental\\nHBAs are fundamentally unsafe and you shouldn't use them if you have a\\nproxy,\\\" why can't I instead draw the line at \\\"login triggers are\\nfundamentally unsafe and you shouldn't use them if you have a proxy\\\"?\\n\\nAnd if you want to handle the across-the-network case, too, then I don't\\naccept the characterization of the problem.\\n\\n> then I don't think\\n> the oracle is that hard to design. We simply set it up not to allow\\n> wraparound connections, or maybe even more narrowly to not allow\\n> wraparound connections to superuser. If the DBA has some weird network\\n> topology where that's not the correct rule, either because they want\\n> to allow wraparound connections or they want to disallow other things,\\n> then yeah they have to tell us what to allow, but I don't really see\\n> why that's an unreasonable expectation.\\n\\nThis seems like a security model that has been carefully gerrymandered\\naround the existing implementation. My argument is that the \\\"weird\\nnetwork topology\\\" isn't weird at all, and it's only dangerous because of\\ndecisions we made (and can unmake).\\n\\nI feel pretty strongly that the design arrow needs to be pointed in the\\nopposite direction. The model needs to be chosen first, to prevent us\\nfrom saying, \\\"We defend against whatever the implementation lets us\\ndefend against today. Good luck, DBAs.\\\"\\n\\n> If machines B and C aren't under our control such that we can\\n> configure them that way, then the configuration is fundamentally\\n> insecure in a way that we can't really fix.\\n\\nHere's probably our biggest point of contention. You're unlikely to\\nconvince me that this is the DBA's fault.\\n\\nIf machines B and C aren't under our control, then our *protocol* is\\nfundamentally insecure in a way that we have the ability to fix, in a\\nway that's already been characterized in security literature.\\n\\n> I think that what you're proposing is that B and C can just be allowed\\n> to proxy to A and A can say \\\"hey, by the way, I'm just gonna let you\\n> in without asking for anything else\\\" and B and C can, when proxying,\\n> react to that by disconnecting before the connection actually goes\\n> through. That's simpler, in a sense. It doesn't require us to set up\\n> the proxy configuration on B and C in a way that matches what\\n> pg_hba.conf allows on A. Instead, B and C can automatically deduce\\n> what connections they should refuse to proxy.\\n\\nRight. It's meant to take the \\\"localhost/wraparound connection\\\" out of a\\nclass of special things we have to worry about, and make it completely\\nboring.\\n\\n> I guess that's nice, but\\n> it feels pretty magical to me. It encourages the DBA not to think\\n> about what B and C should actually be allowed to proxy, and instead\\n> just trust that the automatics are going to prevent any security\\n> disasters.\\n\\nI agree magical behavior is dangerous, if what you think it can do\\ndoesn't match up with what it can actually do. Bugs are always possible,\\nand maybe I'm just not seeing a corner case yet, because I'm talking too\\nmuch and not coding it -- but is this really a case where I'm\\noverpromising? Or does it just feel magical because it's meant to fix\\nthe root issue?\\n\\n(Remember, I'm not arguing against your proxy filter; I just want both.\\nThey complement each other.)\\n\\n> I'm not sure that they always will, and I fear cultivating\\n> too much reliance on them.\\n\\nI can't really argue against this... but I'm not really sure anyone could.\\n\\nMy strawman rephrasing of that is, \\\"we have to make the feature crappy\\nenough that we can blame the DBA when things go wrong.\\\" And even that\\nstrawman could be perfectly reasonable, in situations where the DBA\\nnecessarily has more information than the machine. In this case, though,\\nit seems to me that the two machines have all the information necessary\\nto make a correct decision between them.\\n\\nThanks!\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Fri, 24 Mar 2023 14:47:40 -0700\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\\n> I certainly agree that the security model isn't in a reasonable place\\n> right now. However, I feel that:\\n> \\n> (1) adding an extra predefined role\\n\\n> (2) even adding the connection string security stuff\\n\\nI don't see how these points are related to the question of whether you\\nshould commit your non-superuser-subscription-owners patch or logical-\\nrepl-as-table-owner patch first.\\n\\n\\nMy perspective is that logical replication is an unfinished feature\\nwith an incomplete design. As I said earlier, that's why I backed away\\nfrom trying to do non-superuser subscriptions as a documented feature:\\nit feels like we need to settle some of the underlying pieces first.\\n\\nThere are some big issues, like the security model for replaying\\nchanges. And some smaller issues like feature gaps (RLS doesn't work,\\nif I remember correctly, and maybe something with partitioning). There\\nare potential clashes with other proposals, like the CREATE\\nSUBSCRIPTION ... SERVER, which I hope can be sorted out later. And I\\ndon't feel like I have a good handle on the publisher security model\\nand threats, which hopefully is just a matter of documenting some best\\npractices.\\n\\nEach time we dig into one of these issues I learn something, and I\\nthink others do, too. If we skip past that process and start adding new\\nfeatures on top of this unfinished design, then I think we are setting\\nourselves up for trouble that is going to be harder to fix later.\\n\\nI don't mean to say all of the above issues are blockers or that they\\nshould all be resolved in my favor. But there are enough issues and\\nsome of those issues are serious enough that I feel like it's premature\\nto just go ahead with the non-superuser subscriptions and the\\npredefined role.\\n\\nThere are already users, which complicates things. And you make a good\\npoint that some important users may be already working around the\\nflaws. But there's already a patch and discussion going on for some\\nsecurity model improvements (thanks to you), so let's try to get that\\none in first. If we can't, it's probably because we learned something\\nimportant.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Sat, 25 Mar 2023 12:16:35 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-03-25 12:16:35 -0700, Jeff Davis wrote:\\n> On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\\n> > I certainly agree that the security model isn't in a reasonable place\\n> > right now. However, I feel that:\\n> > \\n> > (1) adding an extra predefined role\\n> \\n> > (2) even adding the connection string security stuff\\n> \\n> I don't see how these points are related to the question of whether you\\n> should commit your non-superuser-subscription-owners patch or logical-\\n> repl-as-table-owner patch first.\\n> \\n> \\n> My perspective is that logical replication is an unfinished feature\\n> with an incomplete design.\\n\\nI agree with that much.\\n\\n\\n> �As I said earlier, that's why I backed away from trying to do non-superuser\\n> subscriptions as a documented feature: it feels like we need to settle some\\n> of the underlying pieces first.\\n\\nI don't agree. The patch allows to use logical rep in a far less dangerous\\nfashion than now. The alternative is to release 16 without a real way to use\\nlogical rep less insanely. Which I think is work.\\n\\n\\n> There are some big issues, like the security model for replaying\\n> changes.\\n\\nThat seems largely unrelated.\\n\\n\\n> And some smaller issues like feature gaps (RLS doesn't work,\\n> if I remember correctly, and maybe something with partitioning).\\n\\nEntirely unrelated?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Mar 2023 10:46:38 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Mar 25, 2023 at 3:16 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Fri, 2023-03-24 at 09:24 -0400, Robert Haas wrote:\\n> > I certainly agree that the security model isn't in a reasonable place\\n> > right now. However, I feel that:\\n> >\\n> > (1) adding an extra predefined role\\n>\\n> > (2) even adding the connection string security stuff\\n>\\n> I don't see how these points are related to the question of whether you\\n> should commit your non-superuser-subscription-owners patch or logical-\\n> repl-as-table-owner patch first.\\n\\nI thought you were asking for those changes to be made before this\\npatch got committed, so that's what I was responding to. If you're\\nasking for it not to be committed at all, that's a different\\ndiscussion.\\n\\n> My perspective is that logical replication is an unfinished feature\\n> with an incomplete design. As I said earlier, that's why I backed away\\n> from trying to do non-superuser subscriptions as a documented feature:\\n> it feels like we need to settle some of the underlying pieces first.\\n\\nI kind of agree with you about the feature itself. Even though the\\nbasic feature works quite well and does something people really want,\\nthere are a lot of loose ends to sort out, and not just about\\nsecurity. But I also want to make some progress. If there are problems\\nwith what I'm proposing that will make us regret committing things\\nright before feature freeze, then we shouldn't. But waiting a whole\\nadditional year to see any kind of improvement is not free; these\\nissues are serious.\\n\\n> I don't mean to say all of the above issues are blockers or that they\\n> should all be resolved in my favor. But there are enough issues and\\n> some of those issues are serious enough that I feel like it's premature\\n> to just go ahead with the non-superuser subscriptions and the\\n> predefined role.\\n>\\n> There are already users, which complicates things. And you make a good\\n> point that some important users may be already working around the\\n> flaws. But there's already a patch and discussion going on for some\\n> security model improvements (thanks to you), so let's try to get that\\n> one in first. If we can't, it's probably because we learned something\\n> important.\\n\\nI think this patch is a lot better-baked and less speculative than\\nthat one. I think that patch is more important, so if they were\\nequally mature, I'd favor getting that one committed first. But that's\\nnot the case.\\n\\nAlso, I don't really understand how we could end up not wanting this\\npatch. I mean there's a lot of things I don't understand that are\\nstill true anyway, so the mere fact that I don't understand how we\\ncould not end up wanting this patch doesn't mean that it couldn't\\nhappen. But like, the current state of play is that subscription\\nowners are always going to be superusers at the time the subscription\\nis created, and literally nobody thinks that's a good idea. Some\\npeople (like me) think that we ought to assume that subscription\\nowners will be and need to be high-privilege users like superusers,\\nbut to my knowledge every such person thinks that it's OK for the\\nsubscription owner to be a non-superuser if they have adequate\\nprivileges. I just think that's a high amount of privileges, not that\\nit has to be all the privileges i.e. superuser. Other people (like\\nyou, AIUI) think that we ought to try to set things up so that\\nsubscription owners can be low-privilege users, in which case we, once\\nagain, don't want the user who owns the subscription to start out a\\nsuperuser. I actually can't imagine anyone defending the idea of\\nhaving the subscription owner always be a superuser at the time they\\nfirst own the subscription. That's a weird rule that can only serve to\\nreduce security. Nor can I imagine anyone saying that forcing\\nsubscriptions to be created only by superusers improves security. I\\ndon't think anyone thinks that.\\n\\nIf we're going to delay this patch, probably for a full year, because\\nof other ongoing discussions, it should be because there is some\\noutcome of those discussions that would involve deciding that this\\npatch isn't needed or should be significantly redesigned. If this\\npatch is going to end up being desirable no matter how those\\ndiscussions turn out, and if it's not going to change significantly no\\nmatter how those discussions turn out, then those discussions aren't a\\nreason not to get it into this release.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Mar 2023 14:06:45 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-03-27 at 10:46 -0700, Andres Freund wrote:\\n> > There are some big issues, like the security model for replaying\\n> > changes.\\n> \\n> That seems largely unrelated.\\n\\nThey are self-evidently related in a fundamental way. The behavior of\\nthe non-superuser-subscription patch depends on the presence of the\\napply-as-table-owner patch.\\n\\nI think I'd like to understand the apply-as-table-owner patch better to\\nunderstand the interaction.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Mar 2023 12:21:15 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, 2023-03-27 at 14:06 -0400, Robert Haas wrote:\\n> I thought you were asking for those changes to be made before this\\n> patch got committed, so that's what I was responding to. If you're\\n> asking for it not to be committed at all, that's a different\\n> discussion.\\n\\nI separately had a complaint (in a separate subthread) about the scope\\nof the predefined role you are introducing, which I think encompasses\\ntwo concepts that should be treated differently and I think that may\\nneed to be revisited later. If you ignore this complaint it wouldn't be\\nthe end of the world.\\n\\nThis subthread is about the order in which the patches get committed\\n(which is a topic you brought up), not whether they are ever to be\\ncommitted.\\n\\n> \\n> I kind of agree with you about the feature itself. Even though the\\n> basic feature works quite well and does something people really want,\\n> there are a lot of loose ends to sort out, and not just about\\n> security. But I also want to make some progress. If there are\\n> problems\\n> with what I'm proposing that will make us regret committing things\\n> right before feature freeze, then we shouldn't. But waiting a whole\\n> additional year to see any kind of improvement is not free; these\\n> issues are serious.\\n\\nThe non-superuser-subscription-owner patch without the apply-as-table-\\nowner patch feels like a facade to me, at least right now. Perhaps I\\ncan be convinced otherwise, but that's what it looks like to me.\\n\\n> \\n> I think this patch is a lot better-baked and less speculative than\\n> that one. I think that patch is more important, so if they were\\n> equally mature, I'd favor getting that one committed first. But\\n> that's\\n> not the case.\\n\\nYou explicitly asked about the order of the patches, which made me\\nthink it was more of an option?\\n\\nIf the apply-as-table-owner patch gets held up for whatever reason, we\\nmight have to make a difficult decision. I'd prefer focus on the apply-\\nas-table-owner patch briefly, and now that it's getting some review\\nattention, we might find out how ready it is quite soon.\\n\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Mar 2023 15:17:27 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\\n> The other patch you posted seems like it makes a lot of progress in\\n> that direction, and I think that should go in first. That was one of\\n> the items I suggested previously[2], so thank you for working on\\n> that.\\n\\nThe above is not a hard objection.\\n\\nI still hold the opinion that the non-superuser subscriptions work is\\nfeels premature without the apply-as-table-owner work. It would be\\ngreat if the other patch ends up ready quickly, which would moot the\\ncommit-ordering question.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 28 Mar 2023 10:52:33 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 24, 2023 at 5:47 PM Jacob Champion <jchampion@timescale.com> wrote:\\n> Okay, but this is walking back from the network example you just\\n> described upthread. Do you still consider that in scope, or...?\\n\\nSorry, I don't know which example you mean.\\n\\n> > If machines B and C aren't under our control such that we can\\n> > configure them that way, then the configuration is fundamentally\\n> > insecure in a way that we can't really fix.\\n>\\n> Here's probably our biggest point of contention. You're unlikely to\\n> convince me that this is the DBA's fault.\\n>\\n> If machines B and C aren't under our control, then our *protocol* is\\n> fundamentally insecure in a way that we have the ability to fix, in a\\n> way that's already been characterized in security literature.\\n\\nI guess I wouldn't have a problem blaming the DBA here, but you seem\\nto be telling me that the security literature has settled on another\\nkind of approach, and I'm not in a position to dispute that. It still\\nfeels weird to me, though.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 30 Mar 2023 08:58:20 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\\n> > The other patch you posted seems like it makes a lot of progress in\\n> > that direction, and I think that should go in first. That was one of\\n> > the items I suggested previously[2], so thank you for working on\\n> > that.\\n>\\n> The above is not a hard objection.\\n\\nThe other patch is starting to go in a direction that is going to have\\nsome conflicts with this one, so I went ahead and committed this one\\nto avoid rebasing pain.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 30 Mar 2023 12:04:51 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jacob Champion (jchampion@timescale.com) wrote:\\n> On 3/20/23 09:32, Robert Haas wrote:\\n> > I think this is the root of our disagreement.\\n> \\n> Agreed.\\n\\nI've read all the way back to the $SUBJECT change to try and get an\\nunderstanding of the questions here and it's not been easy, in part, I\\nthink, due to the verbiage but also the perhaps lack of concrete\\nexamples and instead references to other systems and protocols.\\n\\n> > My understanding of the\\n> > previous discussion is that people think that the major problem here\\n> > is the wraparound-to-superuser attack. That is, in general, we expect\\n> > that when we connect to a database over the network, we expect it to\\n> > do some kind of active authentication, like asking us for a password,\\n> > or asking us for an SSL certificate that isn't just lying around for\\n> > anyone to use. However, in the specific case of a local connection, we\\n> > have a reliable way of knowing who the remote user is without any kind\\n> > of active authentication, namely 'peer' authentication or perhaps even\\n> > 'trust' if we trust all the local users, and so we don't judge it\\n> > unreasonable to allow local connections without any form of active\\n> > authentication. There can be some scenarios where even over a network\\n> > we can know the identity of the person connecting with complete\\n> > certainty, e.g. if endpoints are locked down such that the source IP\\n> > address is a reliable indicator of who is initiating the connection,\\n> > but in general when there's a network involved you don't know who the\\n> > person making the connection is and need to do something extra to\\n> > figure it out.\\n> \\n> Okay, but this is walking back from the network example you just\\n> described upthread. Do you still consider that in scope, or...?\\n\\nThe concern around the network certainly needs to be in-scope overall.\\n\\n> > If you accept this characterization of the problem,\\n> \\n> I'm not going to say yes or no just yet, because I don't understand your\\n> rationale for where to draw the lines.\\n> \\n> If you just want the bare minimum thing that will solve the localhost\\n> case, require_auth landed this week. Login triggers are not yet a thing,\\n> so `require_auth=password,md5,scram-sha-256` ensures active\\n> authentication. You don't even have to disallow localhost connections,\\n> as far as I can tell; they'll work as intended.\\n\\nI do think require_auth helps us move in a positive direction. As I\\nmentioned elsewhere, I don't think we highlight it nearly enough in the\\npostgres_fdw documentation. Let's look at that in a bit more depth with\\nconcrete examples and perhaps everyone will be able to get a bit more\\nunderstanding of the issues.\\n\\nClient is psql\\nProxy is some PG server that's got postgres_fdw\\nTarget is another PG server, that is being connected to from Proxy\\nAuthentication is via GSS/Kerberos with proxied credentials\\n\\nWhat do we want to require the user to configure to make this secure?\\n\\nProxy's pg_hba configured to require GSS auth from Client.\\nTarget's pg_hba configured to require GSS auth from Proxy.\\n\\nWho are we trusting with what? In particular, I'd argue that the user\\nwho is able to install the postgres_fdw extension and the user who is\\nable to issue the CREATE SERVER are largely trusted; at least in so far\\nas the user doing CREATE SERVER is allowed to create the server and\\nthrough that allowed to make outbound connections from the Proxy.\\n\\nTherefore, the Proxy is configured with postgres_fdw and with a trusted\\nuser performing the CREATE SERVER.\\n\\nWhat doesn't this handle today? Connection side-effects are one\\nproblem- once the CREATE SERVER is done, any user with USAGE rights on\\nthe server can create a USER MAPPING for themselves, either with a\\npassword or without one (if they're able to proxy GSS credentials to the\\nsystem). They aren't able to set password_required though, which\\ndefaults to true. However, without having require_auth set, they're\\nable to cause the Proxy to reach an authentication stage with the Target\\nthat might not match what credentials they're supposed to be providing.\\n\\nWe attempt to address this by checking post-auth to Target that we used\\nthe credentials to connect that we expected to- if GSS credentials were\\nproxied, then we expect to use those. If a password was provided then\\nwe expect to use a password to auth (only checked after we see if GSS\\ncredentials were proxied and used). The issue here is 'post-auth' bit,\\nwe'd prefer to fail the connection pre-auth if it isn't what we're\\nexpecting. Should we then explicit set require_auth=gss when GSS\\ncredentials are proxied? Also, if a password is provided, then\\nexplicitly set require_auth=scram-sha-256? Or default to these, at\\nleast, and allow the CREATE SERVER user to override our choices? Or\\nshould it be a USER MAPPING option that's restricted? Or not?\\n\\n> > I think that what you're proposing is that B and C can just be allowed\\n> > to proxy to A and A can say \\\"hey, by the way, I'm just gonna let you\\n> > in without asking for anything else\\\" and B and C can, when proxying,\\n> > react to that by disconnecting before the connection actually goes\\n> > through. That's simpler, in a sense. It doesn't require us to set up\\n> > the proxy configuration on B and C in a way that matches what\\n> > pg_hba.conf allows on A. Instead, B and C can automatically deduce\\n> > what connections they should refuse to proxy.\\n> \\n> Right. It's meant to take the \\\"localhost/wraparound connection\\\" out of a\\n> class of special things we have to worry about, and make it completely\\n> boring.\\n\\nAgain, trying to get at a more concrete example- the concern here is a\\nuser with CREATE SERVER ability could leverage that access to become a\\nsuperuser if the system is configured with 'peer' access, right? A\\nnon-superuser is already prevented from being able to set\\n\\\"password_required=false\\\", perhaps we shouldn't allow them to set\\n\\\"require_auth=none\\\" (or have that effect) either? Perhaps the system\\nshould simply forcibly set require_auth based on the credentials\\nprovided in the USER MAPPING or on the connection and have require_auth\\notherwise restricted to superuser (who could override it if they'd\\nreally like to)? Perhaps if password_required=false we implicitly\\nun-set require_auth, to avoid having to make superusers change their\\nexisting configurations where they've clearly already accepted that\\ncredential-less connections are allowed.\\n\\nAutomatically setting require_auth and restricting the ability of it to\\nbe set on user mappings to superusers doesn't strike me as terribly\\ndifficult to do and seems like it'd prevent this concern.\\n\\nJust to make sure I'm following- Robert's up-thread suggestion of an\\n'outbound pg_hba' would be an additional restriction when it comes to\\nwhat a user who can use CREATE SERVER is allowed to do? I'm not against\\nthe idea of having a way to lock that down.. but it's another level of\\ncomplication certainly and I'm not sure that some external config file\\nor such is the best way to try and deal with that, though I do see how\\nit can have some appeal for certain environments. It does overall\\nstrike me as something we've not tried to address in any way thus far\\nand a pretty large effort that's not likely to make it into PG16, unlike\\nthe possibility of auto-setting require_auth, now that it exists.\\n\\nThanks!\\n\\nStephen\",\n \"msg_date\": \"Thu, 30 Mar 2023 14:13:51 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Friday, March 31, 2023 12:05 AM Robert Haas <robertmhaas@gmail.com> wrote:\\r\\n\\r\\nHi,\\r\\n\\r\\n> \\r\\n> On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\\r\\n> > On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\\r\\n> > > The other patch you posted seems like it makes a lot of progress in\\r\\n> > > that direction, and I think that should go in first. That was one of\\r\\n> > > the items I suggested previously[2], so thank you for working on\\r\\n> > > that.\\r\\n> >\\r\\n> > The above is not a hard objection.\\r\\n> \\r\\n> The other patch is starting to go in a direction that is going to have some\\r\\n> conflicts with this one, so I went ahead and committed this one to avoid\\r\\n> rebasing pain.\\r\\n\\r\\nI noticed the BF[1] report a core dump after this commit.\\r\\n\\r\\n#0 0xfd581864 in _lwp_kill () from /usr/lib/libc.so.12\\r\\n#0 0xfd581864 in _lwp_kill () from /usr/lib/libc.so.12\\r\\n#1 0xfd5817dc in raise () from /usr/lib/libc.so.12\\r\\n#2 0xfd581c88 in abort () from /usr/lib/libc.so.12\\r\\n#3 0x01e6c8d4 in ExceptionalCondition (conditionName=conditionName@entry=0x2007758 \\\"IsTransactionState()\\\", fileName=fileName@entry=0x20565c4 \\\"catcache.c\\\", lineNumber=lineNumber@entry=1208) at assert.c:66\\r\\n#4 0x01e4e404 in SearchCatCacheInternal (cache=0xfd21e500, nkeys=nkeys@entry=1, v1=v1@entry=28985, v2=v2@entry=0, v3=v3@entry=0, v4=v4@entry=0) at catcache.c:1208\\r\\n#5 0x01e4eea0 in SearchCatCache1 (cache=<optimized out>, v1=v1@entry=28985) at catcache.c:1162\\r\\n#6 0x01e66e34 in SearchSysCache1 (cacheId=cacheId@entry=11, key1=key1@entry=28985) at syscache.c:825\\r\\n#7 0x01e98c40 in superuser_arg (roleid=28985) at superuser.c:70\\r\\n#8 0x01c657bc in ApplyWorkerMain (main_arg=<optimized out>) at worker.c:4552\\r\\n#9 0x01c1ceac in StartBackgroundWorker () at bgworker.c:861\\r\\n#10 0x01c23be0 in do_start_bgworker (rw=<optimized out>) at postmaster.c:5762\\r\\n#11 maybe_start_bgworkers () at postmaster.c:5986\\r\\n#12 0x01c2459c in process_pm_pmsignal () at postmaster.c:5149\\r\\n#13 ServerLoop () at postmaster.c:1770\\r\\n#14 0x01c26cdc in PostmasterMain (argc=argc@entry=4, argv=argv@entry=0xffffe0e4) at postmaster.c:1463\\r\\n#15 0x01ee2c8c in main (argc=4, argv=0xffffe0e4) at main.c:200\\r\\n\\r\\nIt looks like the super user check is out of a transaction, I haven't checked why\\r\\nit only failed on one BF animal, but it seems we can put the check into the\\r\\ntransaction like the following:\\r\\n\\r\\ndiff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c\\r\\nindex 6fd674b5d6..08f10fc331 100644\\r\\n--- a/src/backend/replication/logical/worker.c\\r\\n+++ b/src/backend/replication/logical/worker.c\\r\\n@@ -4545,12 +4545,13 @@ ApplyWorkerMain(Datum main_arg)\\r\\n \\t\\treplorigin_session_setup(originid, 0);\\r\\n \\t\\treplorigin_session_origin = originid;\\r\\n \\t\\torigin_startpos = replorigin_session_get_progress(false);\\r\\n-\\t\\tCommitTransactionCommand();\\r\\n \\r\\n \\t\\t/* Is the use of a password mandatory? */\\r\\n \\t\\tmust_use_password = MySubscription->passwordrequired &&\\r\\n \\t\\t\\t!superuser_arg(MySubscription->owner);\\r\\n \\r\\n+\\t\\tCommitTransactionCommand();\\r\\n+\\r\\n\\r\\n[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2023-03-30%2019%3A41%3A08\\r\\n\\r\\nBest Regards,\\r\\nHou Zhijie\\r\\n\",\n \"msg_date\": \"Fri, 31 Mar 2023 01:49:28 +0000\",\n \"msg_from\": \"\\\"houzj.fnst@fujitsu.com\\\" <houzj.fnst@fujitsu.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 30, 2023 at 9:49 PM houzj.fnst@fujitsu.com\\n<houzj.fnst@fujitsu.com> wrote:\\n> It looks like the super user check is out of a transaction, I haven't checked why\\n> it only failed on one BF animal, but it seems we can put the check into the\\n> transaction like the following:\\n\\nThat looks like a reasonable fix but I can't reproduce the problem\\nlocally. I thought the reason why that machine sees the problem might\\nbe that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\\nand the tests still pass. Anyone ideas how to reproduce?\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 31 Mar 2023 16:00:08 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Saturday, April 1, 2023 4:00 AM Robert Haas <robertmhaas@gmail.com>\\r\\n\\r\\nHi,\\r\\n\\r\\n> \\r\\n> On Thu, Mar 30, 2023 at 9:49 PM houzj.fnst@fujitsu.com\\r\\n> <houzj.fnst@fujitsu.com> wrote:\\r\\n> > It looks like the super user check is out of a transaction, I haven't\\r\\n> > checked why it only failed on one BF animal, but it seems we can put\\r\\n> > the check into the transaction like the following:\\r\\n> \\r\\n> That looks like a reasonable fix but I can't reproduce the problem locally. I\\r\\n> thought the reason why that machine sees the problem might be that it uses\\r\\n> -DRELCACHE_FORCE_RELEASE, but I tried that option here and the tests still pass.\\r\\n> Anyone ideas how to reproduce?\\r\\n\\r\\nI think it's a timing problem because superuser_arg() function will cache the\\r\\nroleid that passed in last time, so it might not search the syscache to hit the\\r\\nAssert() check each time. And in the regression test, the roleid cache happened\\r\\nto be invalidated before the superuser_arg() by some concurrently ROLE change(\\r\\nmaybe in subscription.sql and publication.sql).\\r\\n\\r\\nI can reproduce it by using gdb and starting another session to change the ROLE.\\r\\n\\r\\nWhen the apply worker starts, use the gdb to block the apply worker in the\\r\\ntransaction before the super user check. Then start another session to ALTER\\r\\nROLE to invalidate the roleid cache in superuser_arg() which will cause the\\r\\napply worker to search the syscache and hit the Assert().\\r\\n\\r\\n--\\r\\n\\t\\torigin_startpos = replorigin_session_get_progress(false);\\r\\nB*\\t\\tCommitTransactionCommand();\\r\\n\\r\\n\\t\\t/* Is the use of a password mandatory? */\\r\\n\\t\\tmust_use_password = MySubscription->passwordrequired &&\\r\\n\\t\\t\\t! superuser_arg(MySubscription->owner);\\r\\n--\\r\\n\\r\\nBest Regards,\\r\\nHou zj\\r\\n\",\n \"msg_date\": \"Sat, 1 Apr 2023 01:24:05 +0000\",\n \"msg_from\": \"\\\"houzj.fnst@fujitsu.com\\\" <houzj.fnst@fujitsu.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hello Robert,\\n\\n31.03.2023 23:00, Robert Haas wrote:\\n> That looks like a reasonable fix but I can't reproduce the problem\\n> locally. I thought the reason why that machine sees the problem might\\n> be that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\\n> and the tests still pass. Anyone ideas how to reproduce?\\n\\nI've managed to reproduce it using the following script:\\nfor ((i=1;i<=10;i++)); do\\necho \\\"iteration $i\\\"\\necho \\\"\\nCREATE ROLE sub_user;\\nCREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\\n PUBLICATION testpub WITH (connect = false);\\nALTER SUBSCRIPTION testsub ENABLE;\\nDROP SUBSCRIPTION testsub;\\nSELECT pg_sleep(0.001);\\nDROP ROLE sub_user;\\n\\\" | psql\\npsql -c \\\"ALTER SUBSCRIPTION testsub DISABLE;\\\"\\npsql -c \\\"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\\\"\\npsql -c \\\"DROP SUBSCRIPTION testsub;\\\"\\ngrep 'TRAP' server.log && break\\ndone\\n\\niteration 3\\nCREATE ROLE\\n...\\nALTER SUBSCRIPTION\\nWARNING: terminating connection because of crash of another server process\\nDETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because ano\\nther server process exited abnormally and possibly corrupted shared memory.\\nHINT: In a moment you should be able to reconnect to the database and repeat your command.\\nserver closed the connection unexpectedly\\n This probably means the server terminated abnormally\\n before or while processing the request.\\nconnection to server was lost\\nTRAP: failed Assert(\\\"IsTransactionState()\\\"), File: \\\"catcache.c\\\", Line: 1208, PID: 1001242\\n\\nBest regards,\\nAlexander\\n\\n\\n\\n\\n\\nHello Robert,\\n\\n 31.03.2023 23:00, Robert Haas wrote:\\n\\n\\nThat looks like a reasonable fix but I can't reproduce the problem\\nlocally. I thought the reason why that machine sees the problem might\\nbe that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\\nand the tests still pass. Anyone ideas how to reproduce?\\n\\n\\n\\n I've managed to reproduce it using the following script:\\n for ((i=1;i<=10;i++)); do\\n echo \\\"iteration $i\\\"\\n echo \\\"\\n CREATE ROLE sub_user;\\n CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\\n PUBLICATION testpub WITH (connect = false);\\n ALTER SUBSCRIPTION testsub ENABLE;\\n DROP SUBSCRIPTION testsub;\\n SELECT pg_sleep(0.001);\\n DROP ROLE sub_user;\\n \\\" | psql\\n psql -c \\\"ALTER SUBSCRIPTION testsub DISABLE;\\\"\\n psql -c \\\"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\\\"\\n psql -c \\\"DROP SUBSCRIPTION testsub;\\\"\\n grep 'TRAP' server.log && break\\n done\\n\\niteration 3\\n \\n CREATE ROLE\\n \\n ...\\n ALTER SUBSCRIPTION\\n \\n WARNING: terminating connection because of crash of another\\n server process\\n \\n DETAIL: The postmaster has commanded this server process to roll\\n back the current transaction and exit, because ano\\n ther server process exited abnormally and possibly corrupted\\n shared memory.\\n \\n HINT: In a moment you should be able to reconnect to the database\\n and repeat your command.\\n \\n server closed the connection unexpectedly\\n \\n This probably means the server terminated abnormally\\n \\n before or while processing the request.\\n \\n connection to server was lost\\n \\n TRAP: failed Assert(\\\"IsTransactionState()\\\"), File: \\\"catcache.c\\\",\\n Line: 1208, PID: 1001242\\n\\nBest regards,\\n Alexander\",\n \"msg_date\": \"Sat, 1 Apr 2023 19:00:00 +0300\",\n \"msg_from\": \"Alexander Lakhin <exclusion@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"Hi, \\n\\nOn April 1, 2023 9:00:00 AM PDT, Alexander Lakhin <exclusion@gmail.com> wrote:\\n>Hello Robert,\\n>\\n>31.03.2023 23:00, Robert Haas wrote:\\n>> That looks like a reasonable fix but I can't reproduce the problem\\n>> locally. I thought the reason why that machine sees the problem might\\n>> be that it uses -DRELCACHE_FORCE_RELEASE, but I tried that option here\\n>> and the tests still pass. Anyone ideas how to reproduce?\\n>\\n>I've managed to reproduce it using the following script:\\n>for ((i=1;i<=10;i++)); do\\n>echo \\\"iteration $i\\\"\\n>echo \\\"\\n>CREATE ROLE sub_user;\\n>CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\\n> PUBLICATION testpub WITH (connect = false);\\n>ALTER SUBSCRIPTION testsub ENABLE;\\n>DROP SUBSCRIPTION testsub;\\n>SELECT pg_sleep(0.001);\\n>DROP ROLE sub_user;\\n>\\\" | psql\\n>psql -c \\\"ALTER SUBSCRIPTION testsub DISABLE;\\\"\\n>psql -c \\\"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\\\"\\n>psql -c \\\"DROP SUBSCRIPTION testsub;\\\"\\n>grep 'TRAP' server.log && break\\n>done\\n>\\n>iteration 3\\n>CREATE ROLE\\n>...\\n>ALTER SUBSCRIPTION\\n>WARNING: terminating connection because of crash of another server process\\n>DETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because ano\\n>ther server process exited abnormally and possibly corrupted shared memory.\\n>HINT: In a moment you should be able to reconnect to the database and repeat your command.\\n>server closed the connection unexpectedly\\n> This probably means the server terminated abnormally\\n> before or while processing the request.\\n>connection to server was lost\\n>TRAP: failed Assert(\\\"IsTransactionState()\\\"), File: \\\"catcache.c\\\", Line: 1208, PID: 1001242\\n\\nErrors like that are often easier to reproduce with clobber caches (or whatever the name is these days) enabled.\\n\\nAndres\\n-- \\nSent from my Android device with K-9 Mail. Please excuse my brevity.\\n\\n\\n\",\n \"msg_date\": \"Sat, 01 Apr 2023 16:07:14 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Apr 1, 2023 at 12:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:\\n> I've managed to reproduce it using the following script:\\n> for ((i=1;i<=10;i++)); do\\n> echo \\\"iteration $i\\\"\\n> echo \\\"\\n> CREATE ROLE sub_user;\\n> CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\\n> PUBLICATION testpub WITH (connect = false);\\n> ALTER SUBSCRIPTION testsub ENABLE;\\n> DROP SUBSCRIPTION testsub;\\n> SELECT pg_sleep(0.001);\\n> DROP ROLE sub_user;\\n> \\\" | psql\\n> psql -c \\\"ALTER SUBSCRIPTION testsub DISABLE;\\\"\\n> psql -c \\\"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\\\"\\n> psql -c \\\"DROP SUBSCRIPTION testsub;\\\"\\n> grep 'TRAP' server.log && break\\n> done\\n\\nAfter a bit of experimentation this repro worked for me -- I needed\\n-DRELCACHE_FORCE_RELEASE as well, and a bigger iteration count. I\\nverified that the patch fixed it, and committed the patch with the\\naddition of a comment.\\n\\nThanks very much for this repro, and likewise many thanks to Hou\\nZhijie for the report and patch.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 3 Apr 2023 13:56:31 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 30, 2023 at 9:35 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Tue, Mar 28, 2023 at 1:52 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > On Fri, 2023-03-24 at 00:17 -0700, Jeff Davis wrote:\\n> > > The other patch you posted seems like it makes a lot of progress in\\n> > > that direction, and I think that should go in first. That was one of\\n> > > the items I suggested previously[2], so thank you for working on\\n> > > that.\\n> >\\n> > The above is not a hard objection.\\n>\\n> The other patch is starting to go in a direction that is going to have\\n> some conflicts with this one, so I went ahead and committed this one\\n> to avoid rebasing pain.\\n>\\n\\nDo we need to have a check for this new option \\\"password_required\\\" in\\nmaybe_reread_subscription() where we \\\"Exit if any parameter that\\naffects the remote connection was changed.\\\"? This new option is\\nrelated to the remote connection so I thought it is worth considering\\nwhether we want to exit and restart the apply worker when this option\\nis changed.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Sat, 8 Apr 2023 11:04:53 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Sat, Apr 8, 2023 at 1:35 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> Do we need to have a check for this new option \\\"password_required\\\" in\\n> maybe_reread_subscription() where we \\\"Exit if any parameter that\\n> affects the remote connection was changed.\\\"? This new option is\\n> related to the remote connection so I thought it is worth considering\\n> whether we want to exit and restart the apply worker when this option\\n> is changed.\\n\\nHmm, good question. I think that's probably a good idea. If the\\ncurrent connection is already working, the only possible result of\\ngetting rid of it and trying to create a new one is that it might now\\nfail instead, but someone might want that behavior. Otherwise, they'd\\ninstead find the failure at a later, maybe less convenient, time.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 10 Apr 2023 11:45:11 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 10, 2023 at 9:15 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Sat, Apr 8, 2023 at 1:35 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > Do we need to have a check for this new option \\\"password_required\\\" in\\n> > maybe_reread_subscription() where we \\\"Exit if any parameter that\\n> > affects the remote connection was changed.\\\"? This new option is\\n> > related to the remote connection so I thought it is worth considering\\n> > whether we want to exit and restart the apply worker when this option\\n> > is changed.\\n>\\n> Hmm, good question. I think that's probably a good idea. If the\\n> current connection is already working, the only possible result of\\n> getting rid of it and trying to create a new one is that it might now\\n> fail instead, but someone might want that behavior. Otherwise, they'd\\n> instead find the failure at a later, maybe less convenient, time.\\n>\\n\\nI think additionally, we should check that the new owner of the\\nsubscription is not a superuser, otherwise, anyway, this parameter is\\nignored. Please find the attached to add this check.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\",\n \"msg_date\": \"Tue, 11 Apr 2023 15:23:18 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Apr 11, 2023 at 5:53 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> I think additionally, we should check that the new owner of the\\n> subscription is not a superuser, otherwise, anyway, this parameter is\\n> ignored. Please find the attached to add this check.\\n\\nI don't see why we should check that. It makes this different from all\\nthe other cases and I don't see any benefit.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 11 Apr 2023 10:51:39 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Apr 11, 2023 at 8:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Tue, Apr 11, 2023 at 5:53 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > I think additionally, we should check that the new owner of the\\n> > subscription is not a superuser, otherwise, anyway, this parameter is\\n> > ignored. Please find the attached to add this check.\\n>\\n> I don't see why we should check that. It makes this different from all\\n> the other cases and I don't see any benefit.\\n>\\n\\nI thought it would be better if we don't restart the worker unless it\\nis required. In case, the subscription's owner is a superuser, the\\n'password_required' is ignored, so why restart the apply worker when\\nsomebody changes it in such a case? I understand that there may not be\\na need to change the 'password_required' option when the\\nsubscription's owner is the superuser but one may first choose to\\nchange the password_required flag and then the owner of a subscription\\nto a non-superuser. Anyway, I don't think as such there is any problem\\nwith restarting the worker even when the subscription owner is a\\nsuperuser, so adjusted the check accordingly.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\",\n \"msg_date\": \"Wed, 12 Apr 2023 08:26:02 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> Anyway, I don't think as such there is any problem\\n> with restarting the worker even when the subscription owner is a\\n> superuser, so adjusted the check accordingly.\\n\\nLGTM. I realize we could do more sophisticated things here, but I\\nthink it's better to keep the code simple.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 12 Apr 2023 08:19:51 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 3/30/23 05:58, Robert Haas wrote:\\n> On Fri, Mar 24, 2023 at 5:47 PM Jacob Champion <jchampion@timescale.com> wrote:\\n>> Okay, but this is walking back from the network example you just\\n>> described upthread. Do you still consider that in scope, or...?\\n> \\n> Sorry, I don't know which example you mean.\\n\\nThe symmetrical proxy situation you described, where all the proxies are\\nmutually trusting. While it's easier to secure that setup than the\\nasymmetrical ones, it's also not a localhost-only situation anymore, and\\nthe moment you open up to other machines is where I think your\\ncharacterization runs into trouble.\\n\\n> I guess I wouldn't have a problem blaming the DBA here, but you seem\\n> to be telling me that the security literature has settled on another\\n> kind of approach, and I'm not in a position to dispute that. It still\\n> feels weird to me, though.\\n\\nIf it helps, [1] is a paper that helped me wrap my head around some of\\nit. It's focused on capability systems and an academic audience, but the\\n\\\"Avoiding Confused Deputy Problems\\\" section starting on page 11 is a\\ngood place to jump to for the purposes of this discussion.\\n\\n--Jacob\\n\\n[1] https://srl.cs.jhu.edu/pubs/SRL2003-02.pdf\\n\\n\\n\",\n \"msg_date\": \"Wed, 12 Apr 2023 11:23:01 -0700\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On 3/30/23 11:13, Stephen Frost wrote:\\n>> Okay, but this is walking back from the network example you just\\n>> described upthread. Do you still consider that in scope, or...?\\n> \\n> The concern around the network certainly needs to be in-scope overall.\\n\\nSounds good!\\n\\n> Who are we trusting with what? In particular, I'd argue that the user\\n> who is able to install the postgres_fdw extension and the user who is\\n> able to issue the CREATE SERVER are largely trusted; at least in so far\\n> as the user doing CREATE SERVER is allowed to create the server and\\n> through that allowed to make outbound connections from the Proxy.\\n> \\n> Therefore, the Proxy is configured with postgres_fdw and with a trusted\\n> user performing the CREATE SERVER.\\n> \\n> What doesn't this handle today? Connection side-effects are one\\n> problem- once the CREATE SERVER is done, any user with USAGE rights on\\n> the server can create a USER MAPPING for themselves, either with a\\n> password or without one (if they're able to proxy GSS credentials to the\\n> system). They aren't able to set password_required though, which\\n> defaults to true. However, without having require_auth set, they're\\n> able to cause the Proxy to reach an authentication stage with the Target\\n> that might not match what credentials they're supposed to be providing.\\n> \\n> We attempt to address this by checking post-auth to Target that we used\\n> the credentials to connect that we expected to- if GSS credentials were\\n> proxied, then we expect to use those. If a password was provided then\\n> we expect to use a password to auth (only checked after we see if GSS\\n> credentials were proxied and used). The issue here is 'post-auth' bit,\\n> we'd prefer to fail the connection pre-auth if it isn't what we're\\n> expecting.\\n\\nRight. Keep in mind that require_auth is post-auth, though; it can't fix\\nthat issue, so it doesn't fix any connection side-effect problems at all.\\n\\n> Should we then explicit set require_auth=gss when GSS\\n> credentials are proxied? Also, if a password is provided, then\\n> explicitly set require_auth=scram-sha-256? Or default to these, at\\n> least, and allow the CREATE SERVER user to override our choices? Or\\n> should it be a USER MAPPING option that's restricted? Or not?\\nIMO, yes -- whatever credentials the proxy is forwarding from the user,\\nthe proxy should be checking that the server has actually used them. The\\nperson with the ability to create a USER MAPPING should probably not\\nhave the ability to override that check.\\n\\n>>> I think that what you're proposing is that B and C can just be allowed\\n>>> to proxy to A and A can say \\\"hey, by the way, I'm just gonna let you\\n>>> in without asking for anything else\\\" and B and C can, when proxying,\\n>>> react to that by disconnecting before the connection actually goes\\n>>> through. That's simpler, in a sense. It doesn't require us to set up\\n>>> the proxy configuration on B and C in a way that matches what\\n>>> pg_hba.conf allows on A. Instead, B and C can automatically deduce\\n>>> what connections they should refuse to proxy.\\n>>\\n>> Right. It's meant to take the \\\"localhost/wraparound connection\\\" out of a\\n>> class of special things we have to worry about, and make it completely\\n>> boring.\\n> \\n> Again, trying to get at a more concrete example- the concern here is a\\n> user with CREATE SERVER ability could leverage that access to become a\\n> superuser if the system is configured with 'peer' access, right?\\n\\nOr 'trust localhost', or 'ident [postgres user]', yes.\\n\\n> A\\n> non-superuser is already prevented from being able to set\\n> \\\"password_required=false\\\", perhaps we shouldn't allow them to set\\n> \\\"require_auth=none\\\" (or have that effect) either?\\n\\nI think that sounds reasonable.\\n\\n> Perhaps the system\\n> should simply forcibly set require_auth based on the credentials\\n> provided in the USER MAPPING or on the connection and have require_auth\\n> otherwise restricted to superuser (who could override it if they'd\\n> really like to)? Perhaps if password_required=false we implicitly\\n> un-set require_auth, to avoid having to make superusers change their\\n> existing configurations where they've clearly already accepted that\\n> credential-less connections are allowed.\\n\\nMm, I think I like the first idea better. If you've set a password,\\nwouldn't you like to know if the server ignored it? If password_required\\nis false, *and* you don't have a password, then we can drop require_auth\\nwithout issue.\\n\\n> Automatically setting require_auth and restricting the ability of it to\\n> be set on user mappings to superusers doesn't strike me as terribly\\n> difficult to do and seems like it'd prevent this concern.\\n> \\n> Just to make sure I'm following- Robert's up-thread suggestion of an\\n> 'outbound pg_hba' would be an additional restriction when it comes to\\n> what a user who can use CREATE SERVER is allowed to do?\\n\\nYes. That can provide additional safety in the case where you really\\nneed to take the require_auth checks away for whatever reason. I think\\nit's just a good in-depth measure, and if we don't extend the protocol\\nin some way to do a pre-auth check, it's also the way for the DBA to\\nbless known-good connection paths.\\n\\nThanks,\\n--Jacob\\n\\n\\n\",\n \"msg_date\": \"Wed, 12 Apr 2023 11:24:33 -0700\",\n \"msg_from\": \"Jacob Champion <jchampion@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security\"\n },\n {\n \"msg_contents\": \"On Wed, Apr 12, 2023 at 5:50 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > Anyway, I don't think as such there is any problem\\n> > with restarting the worker even when the subscription owner is a\\n> > superuser, so adjusted the check accordingly.\\n>\\n> LGTM.\\n>\\n\\nThanks. I am away for a few days so can push it only next week.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 13 Apr 2023 08:02:07 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 13, 2023 at 8:02 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>\\n> On Wed, Apr 12, 2023 at 5:50 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n> >\\n> > On Tue, Apr 11, 2023 at 10:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > > Anyway, I don't think as such there is any problem\\n> > > with restarting the worker even when the subscription owner is a\\n> > > superuser, so adjusted the check accordingly.\\n> >\\n> > LGTM.\\n> >\\n>\\n> Thanks. I am away for a few days so can push it only next week.\\n>\\n\\nPushed. I noticed that we didn't display this new subscription option\\n'password_required' in \\\\dRs+:\\n\\npostgres=# \\\\dRs+\\n\\n List of subscriptions\\n Name | Owner | Enabled | Publication | Binary | Streaming |\\nTwo-phase commit | Disable on error | Origin | Run as Owner? |\\nSynchronous commit | Conninfo | Skip LSN\\n\\nIs that intentional? Sorry, if it was discussed previously because I\\nhaven't followed this discussion in detail.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 20 Apr 2023 10:38:02 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> Pushed. I noticed that we didn't display this new subscription option\\n> 'password_required' in \\\\dRs+:\\n>\\n> postgres=# \\\\dRs+\\n>\\n> List of subscriptions\\n> Name | Owner | Enabled | Publication | Binary | Streaming |\\n> Two-phase commit | Disable on error | Origin | Run as Owner? |\\n> Synchronous commit | Conninfo | Skip LSN\\n>\\n> Is that intentional? Sorry, if it was discussed previously because I\\n> haven't followed this discussion in detail.\\n\\nNo, I don't think that's intentional. I just didn't think about it.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 20 Apr 2023 16:18:58 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, 21 Apr 2023 at 01:49, Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > Pushed. I noticed that we didn't display this new subscription option\\n> > 'password_required' in \\\\dRs+:\\n> >\\n> > postgres=# \\\\dRs+\\n> >\\n> > List of subscriptions\\n> > Name | Owner | Enabled | Publication | Binary | Streaming |\\n> > Two-phase commit | Disable on error | Origin | Run as Owner? |\\n> > Synchronous commit | Conninfo | Skip LSN\\n> >\\n> > Is that intentional? Sorry, if it was discussed previously because I\\n> > haven't followed this discussion in detail.\\n>\\n> No, I don't think that's intentional. I just didn't think about it.\\n\\nHere is a patch to display Password required with \\\\dRs+ command. Also\\nadded one test to describe subscription when password_required is\\nfalse, as all the existing tests were there only for password_required\\nas true.\\n\\nRegards,\\nVignesh\",\n \"msg_date\": \"Fri, 21 Apr 2023 12:29:50 +0530\",\n \"msg_from\": \"vignesh C <vignesh21@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 21, 2023 at 12:30 PM vignesh C <vignesh21@gmail.com> wrote:\\n>\\n> On Fri, 21 Apr 2023 at 01:49, Robert Haas <robertmhaas@gmail.com> wrote:\\n> >\\n> > On Thu, Apr 20, 2023 at 1:08 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > > Pushed. I noticed that we didn't display this new subscription option\\n> > > 'password_required' in \\\\dRs+:\\n> > >\\n> > > postgres=# \\\\dRs+\\n> > >\\n> > > List of subscriptions\\n> > > Name | Owner | Enabled | Publication | Binary | Streaming |\\n> > > Two-phase commit | Disable on error | Origin | Run as Owner? |\\n> > > Synchronous commit | Conninfo | Skip LSN\\n> > >\\n> > > Is that intentional? Sorry, if it was discussed previously because I\\n> > > haven't followed this discussion in detail.\\n> >\\n> > No, I don't think that's intentional. I just didn't think about it.\\n>\\n> Here is a patch to display Password required with \\\\dRs+ command. Also\\n> added one test to describe subscription when password_required is\\n> false, as all the existing tests were there only for password_required\\n> as true.\\n>\\n\\nLGTM. Let's see if Robert or others have any comments, otherwise, I'll\\npush this early next week.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 21 Apr 2023 17:48:51 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 21, 2023 at 8:19 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> LGTM. Let's see if Robert or others have any comments, otherwise, I'll\\n> push this early next week.\\n\\nLGTM too.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 21 Apr 2023 08:51:08 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 21, 2023 at 6:21 PM Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Fri, Apr 21, 2023 at 8:19 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > LGTM. Let's see if Robert or others have any comments, otherwise, I'll\\n> > push this early next week.\\n>\\n> LGTM too.\\n>\\n\\nPushed.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Mon, 24 Apr 2023 11:28:48 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tuesday, April 4, 2023 1:57 AM Robert Haas <robertmhaas@gmail.com> wrote:\\r\\n> \\r\\n> On Sat, Apr 1, 2023 at 12:00 PM Alexander Lakhin <exclusion@gmail.com>\\r\\n> wrote:\\r\\n> > I've managed to reproduce it using the following script:\\r\\n> > for ((i=1;i<=10;i++)); do\\r\\n> > echo \\\"iteration $i\\\"\\r\\n> > echo \\\"\\r\\n> > CREATE ROLE sub_user;\\r\\n> > CREATE SUBSCRIPTION testsub CONNECTION 'dbname=db'\\r\\n> > PUBLICATION testpub WITH (connect = false); ALTER SUBSCRIPTION\\r\\n> > testsub ENABLE; DROP SUBSCRIPTION testsub; SELECT pg_sleep(0.001);\\r\\n> > DROP ROLE sub_user; \\\" | psql psql -c \\\"ALTER SUBSCRIPTION testsub\\r\\n> > DISABLE;\\\"\\r\\n> > psql -c \\\"ALTER SUBSCRIPTION testsub SET (slot_name = NONE);\\\"\\r\\n> > psql -c \\\"DROP SUBSCRIPTION testsub;\\\"\\r\\n> > grep 'TRAP' server.log && break\\r\\n> > done\\r\\n> \\r\\n> After a bit of experimentation this repro worked for me -- I needed\\r\\n> -DRELCACHE_FORCE_RELEASE as well, and a bigger iteration count. I verified\\r\\n> that the patch fixed it, and committed the patch with the addition of a\\r\\n> comment.\\r\\n\\r\\nThanks for pushing!\\r\\n\\r\\nWhile testing this, I found a similar problem in table sync worker,\\r\\nas we also invoke superuser_arg() in table sync worker which is not in a\\r\\ntransaction.\\r\\n\\r\\nLogicalRepSyncTableStart\\r\\n...\\r\\n\\t/* Is the use of a password mandatory? */\\r\\n\\tmust_use_password = MySubscription->passwordrequired &&\\r\\n\\t\\t!superuser_arg(MySubscription->owner);\\r\\n\\r\\n#0 0x00007f18bb55aaff in raise () from /lib64/libc.so.6\\r\\n#1 0x00007f18bb52dea5 in abort () from /lib64/libc.so.6\\r\\n#2 0x0000000000b69a22 in ExceptionalCondition (conditionName=0xda4338 \\\"IsTransactionState()\\\", fileName=0xda403e \\\"catcache.c\\\", lineNumber=1208) at assert.c:66\\r\\n#3 0x0000000000b4842a in SearchCatCacheInternal (cache=0x27cab80, nkeys=1, v1=10, v2=0, v3=0, v4=0) at catcache.c:1208\\r\\n#4 0x0000000000b48329 in SearchCatCache1 (cache=0x27cab80, v1=10) at catcache.c:1162\\r\\n#5 0x0000000000b630c7 in SearchSysCache1 (cacheId=11, key1=10) at syscache.c:825\\r\\n#6 0x0000000000b982e3 in superuser_arg (roleid=10) at superuser.c:70\\r\\n\\r\\nI can reproduce this via gdb following similar steps in [1].\\r\\n\\r\\nI think we need to move this call into a transaction as well and here is an attempt\\r\\nto do that.\\r\\n\\r\\n[1] https://www.postgresql.org/message-id/OS0PR01MB5716E596E4FB83DE46F592FE948C9%40OS0PR01MB5716.jpnprd01.prod.outlook.com\\r\\n\\r\\nBest Regards,\\r\\nHou zj\",\n \"msg_date\": \"Fri, 12 May 2023 09:58:31 +0000\",\n \"msg_from\": \"\\\"Zhijie Hou (Fujitsu)\\\" <houzj.fnst@fujitsu.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\\n<houzj.fnst@fujitsu.com> wrote:\\n>\\n>\\n> I can reproduce this via gdb following similar steps in [1].\\n>\\n> I think we need to move this call into a transaction as well and here is an attempt\\n> to do that.\\n>\\n\\nI am able to reproduce this issue following the steps mentioned by you\\nand the proposed patch to fix the issue looks good to me.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 13 Jun 2023 14:25:50 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>\\n> On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\\n> <houzj.fnst@fujitsu.com> wrote:\\n> >\\n> >\\n> > I can reproduce this via gdb following similar steps in [1].\\n> >\\n> > I think we need to move this call into a transaction as well and here is an attempt\\n> > to do that.\\n> >\\n>\\n> I am able to reproduce this issue following the steps mentioned by you\\n> and the proposed patch to fix the issue looks good to me.\\n>\\n\\nI'll push this tomorrow unless there are any suggestions or comments.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 13 Jun 2023 14:29:05 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>\\n> On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\\n> <houzj.fnst@fujitsu.com> wrote:\\n> >\\n> >\\n> > I can reproduce this via gdb following similar steps in [1].\\n> >\\n> > I think we need to move this call into a transaction as well and here is an attempt\\n> > to do that.\\n> >\\n>\\n> I am able to reproduce this issue following the steps mentioned by you\\n> and the proposed patch to fix the issue looks good to me.\\n>\\n\\nToday, again looking at the patch, it seems to me that it would be\\nbetter if we can fix this without starting a new transaction. Won't it\\nbe better if we move this syscall to a place where we are fetching\\nrelstate (GetSubscriptionRelState()) a few lines above? I understand\\nby doing that in some cases like when copy_data = false, we may do\\nthis syscall unnecessarily but OTOH, starting a new transaction just\\nfor a syscall (superuser_arg()) also doesn't seem like a good idea to\\nme.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Wed, 14 Jun 2023 07:41:01 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Wednesday, June 14, 2023 10:11 AM Amit Kapila <amit.kapila16@gmail.com> wrote:\\r\\n> \\r\\n> On Tue, Jun 13, 2023 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:\\r\\n> >\\r\\n> > On Fri, May 12, 2023 at 3:28 PM Zhijie Hou (Fujitsu)\\r\\n> > <houzj.fnst@fujitsu.com> wrote:\\r\\n> > >\\r\\n> > >\\r\\n> > > I can reproduce this via gdb following similar steps in [1].\\r\\n> > >\\r\\n> > > I think we need to move this call into a transaction as well and\\r\\n> > > here is an attempt to do that.\\r\\n> > >\\r\\n> >\\r\\n> > I am able to reproduce this issue following the steps mentioned by you\\r\\n> > and the proposed patch to fix the issue looks good to me.\\r\\n> >\\r\\n> \\r\\n> Today, again looking at the patch, it seems to me that it would be better if we\\r\\n> can fix this without starting a new transaction. Won't it be better if we move this\\r\\n> syscall to a place where we are fetching relstate (GetSubscriptionRelState()) a\\r\\n> few lines above? I understand by doing that in some cases like when copy_data\\r\\n> = false, we may do this syscall unnecessarily but OTOH, starting a new\\r\\n> transaction just for a syscall (superuser_arg()) also doesn't seem like a good\\r\\n> idea to me.\\r\\n\\r\\nMakes sense to me, here is the updated patch which does the same.\\r\\n\\r\\nBest Regards,\\r\\nHou zj\",\n \"msg_date\": \"Wed, 14 Jun 2023 03:53:54 +0000\",\n \"msg_from\": \"\\\"Zhijie Hou (Fujitsu)\\\" <houzj.fnst@fujitsu.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On 2023-Jun-13, Amit Kapila wrote:\\n\\n> I'll push this tomorrow unless there are any suggestions or comments.\\n\\nNote the proposed commit message is wrong about which commit is to blame\\nfor the original problem -- it mentions e7e7da2f8d57 twice, but one of\\nthem is actually c3afe8cf5a1e.\\n\\n-- \\nÁlvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Thu, 15 Jun 2023 19:48:44 +0200\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Thu, Jun 15, 2023 at 11:18 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\\n>\\n> On 2023-Jun-13, Amit Kapila wrote:\\n>\\n> > I'll push this tomorrow unless there are any suggestions or comments.\\n>\\n> Note the proposed commit message is wrong about which commit is to blame\\n> for the original problem -- it mentions e7e7da2f8d57 twice, but one of\\n> them is actually c3afe8cf5a1e.\\n>\\n\\nRight, I also noticed this and changed it before pushing, See\\nhttps://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=b5c517379a40fa1af84c0852aa3730a5875a6482\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Fri, 16 Jun 2023 07:37:42 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Non-superuser subscription owners\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 27, 2023 at 7:37 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Mon, 2023-02-27 at 16:13 -0500, Robert Haas wrote:\\n> > On Mon, Feb 27, 2023 at 1:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > > I think you are saying that we should still run Alice's code with\\n> > > the\\n> > > privileges of Bob, but somehow make that safe(r) for Bob. Is that\\n> > > right?\\n> >\\n> > Yeah. That's the idea I was floating, at least.\\n>\\n> Isn't that a hard problem; maybe impossible?\\n\\nI want to flesh out the ideas I previously articulated in this area a bit more.\\n\\nAs a refresher, the scenario I'm talking about is any one in which one\\nuser, who I'll call Bob, does something that results in executing code\\nprovided by another user, who I'll call Alice. The most obvious way\\nthat this can happen is if Bob performs some operation that targets a\\ntable owned by Alice. That operation might be DML, like an INSERT or\\nUPDATE; or it might be some other kind of maintenance command that can\\ncause code execution, like REINDEX, which can evaluate index\\nexpressions. The code being executed might be run either as Alice or\\nas Bob, depending on how it's been attached to the table and what\\noperation is being performed and maybe whether some function or\\nprocedure that might contain it is SECURITY INVOKER or SECURITY\\nDEFINER. Regardless of the details, our concern is that Alice's code\\nmight do something that Bob does not like. This is a particularly\\nlively concern if the code happens to be running with the privileges\\nof Bob, because then Alice might try to do something like access\\nobjects for which Bob has permissions and Alice does not. But the\\nproblems don't completely go away if the code is being run as Alice,\\nbecause even then, Alice could try to manipulate the session state in\\nsome way that will cause Bob to hose himself later on. The existing\\nSECURITY_RESTRICTED_OPERATION flag defends against some scenarios of\\nthis type, but at present we also rely heavily on Bob being *very*\\ncareful, as Jeff has highlighted rather compellingly.\\n\\nI think we can do better, both in the case where Bob is running code\\nprovided by Alice using his own permissions, and also in the case\\nwhere Bob is running code provided by Alice using Alice's permissions.\\nTo that end, I'd like to define a few terms. First, let's define the\\nprovider of a piece of code as either (a) the owner of the function or\\nprocedure that contains it or (b) the owner of the object to which\\nit's directly attached or (c) the session user, for code directly\\nentered at top level. For example, if Alice owns a table T1 and\\napplies a default expression which uses a function provided by\\nCharlie, and Bob then inserts into T1, then Bob provides the insert\\nstatement, Alice provides the default expression, and Charlie provides\\nthe code inside the function. I assert that in every context where\\nPostgreSQL evaluates expressions or runs SQL statements, there's a\\nwell-defined provider for the expression or statement, and we can make\\nthe system track it if we want to. Second, I'd like to define trust.\\nUsers trust themselves, and they also trust users who have a superset\\nof their permissions, a category that most typically just includes\\nsuperusers but could include others if role grants are in use. A user\\ncan also declare through some mechanism or other that they trust\\nanother user even if that other user does not have a superset of their\\npermissions. Such a declaration carries the risk that the trusted user\\ncould hijack the trusting user's permissions; we would document and\\ndisclaim this risk.\\n\\nFinally, let's define sandboxing. When code is sandboxed, the set of\\noperations that it is allowed to perform is restricted. Sandboxing\\nisn't necessarily all or nothing; there can be different categories of\\noperations and we can allow some and deny others, if we wish.\\nObviously this is quite a bit of work to implement, but I don't think\\nit's unmanageable. YMMV. To keep things simple for purposes of\\ndiscussion, I'm going to just define two levels of sandboxing for the\\nmoment; I think we might want more. If code is fully sandboxed, it can\\nonly do the following things:\\n\\n1. Compute stuff. There's no restriction on the permissible amount of\\ncompute; if you call untrusted code, nothing prevents it from running\\nforever.\\n2. Call other code. This may be done by a function call or a command\\nsuch as CALL or DO, all subject to the usual permissions checks but no\\nfurther restrictions.\\n3. Access the current session state, without modifying it. For\\nexample, executing SHOW or current_setting() is fine.\\n4. Transiently modify the current session state in ways that are\\nnecessarily reversed before returning to the caller. For example, an\\nEXCEPTION block or a configuration change driven by proconfig is fine.\\n5. Produce messages at any log level. This includes any kind of ERROR.\\n\\nFully sandboxed code can't access or modify data beyond what gets\\npassed to it, with the exception of the session state mentioned above.\\nThis includes data inside of PostgreSQL, like tables or statistics, as\\nwell as data outside of PostgreSQL, like files that it might try to\\nread by calling pg_read_file(). If it tries, an ERROR occurs.\\n\\nPartially sandboxed code is much less restricted. Partially sandboxed\\ncode can do almost anything that unsandboxed code can do, but with one\\nimportant exception: it can't modify the session state. This means it\\ncan't run commands like CLOSE, DEALLOCATE, DECLARE, DISCARD, EXECUTE,\\nFETCH, LISTEN, MOVE, PREPARE, or UNLISTEN. Nor can it try to COMMIT or\\nROLLBACK the current transaction or set up a SAVEPOINT or ROLLBACK TO\\nSAVEPOINT. Nor can it use SET or set_config() to change a parameter\\nvalue.\\n\\nWith those definitions in hand, I think it's possible to propose a\\nmeaningful security model:\\n\\nRule #1: If the current user does not trust the provider, the code is\\nfully sandboxed.\\nRule #2: If the session user does not trust the provider either of the\\ncurrently-running code or of any other code that's still on the call\\nstack, the code is partially sandboxed.\\n\\nLet's take a few examples. First, suppose Alice has a table and it has\\nsome associated code for which the provider is always Alice. That is,\\nshe may have default expressions or index expressions for which she is\\nnecessarily the provider, and she may have triggers, but in this\\nexample she owns the functions or procedures called by those triggers\\nand is thus the provider for those as well. Now, Bob, who does not\\ntrust Alice, does something to Alice's table. The code might run as\\nBob (by default) and then it will be fully sandboxed because of rule\\n#1. Or there might be a SECURITY DEFINER function or procedure\\ninvolved causing the code to run as Alice, in which case the code will\\nbe partially sandboxed because of rule #2. I argue that Bob is pretty\\nsafe here. Alice can't make any durable changes to Bob's session state\\nno matter what she does, and if she provides code that runs as Bob it\\ncan only do innocuous things like calculating x+y or x || y or running\\ngenerate_series() or examining current_role. Yes, it could go into a\\nloop, but that doesn't compromise Bob's account: he can hit ^C or set\\nstatement_timeout. If she provides code that runs as herself it can\\nmake use of her privileges (but not Bob's) as long as it doesn't try\\nto touch the session state. So Bob is pretty safe.\\n\\nNow, suppose instead that Bob has a table but some code that is\\nattached to it can call a function that is owned by Alice. In this\\ncase, as long as everything on the call stack is provided by Bob,\\nthere are no restrictions. But as soon as we enter Alice's function,\\nthe code is fully sandboxed unless it arranges to switch to Alice's\\npermissions using SECURITY DEFINER, in which case it's still partially\\nsandboxed. Again, it's hard to see how Alice can get any leverage\\nhere.\\n\\nFinally, suppose Alice has a table and attaches a trigger to it that\\ncalls a function provided by Charlie. Bob now does something to this\\ntable that results in the execution of this trigger. If the current\\nuser -- which will be either Alice or Bob depending on whether the\\nfunction is SECURITY DEFINER -- does not trust Charlie, the code\\ninside the trigger is going to run fully sandboxed because of rule #1.\\nBut even if the current user does trust Charlie, the code inside the\\ntrigger is still going to be partially sandboxed unless Bob trusts\\nBOTH Alice AND Charlie because of rule #2. This seems appropriate,\\nbecause in this situation, either Alice or Charlie could be trying to\\nfool Bob into taking some action he doesn't intend to take by\\ntinkering with his session.\\n\\nIn general if we have a great big call stack that involves calling a\\nwhole bunch of functions either as SECURITY INVOKER or as SECURITY\\nDEFINER, changing the session state is blocked unless the session user\\ntrusts the owners of all of those functions. And if we got to any of\\nthose functions by means of code attached directly to tables, like an\\nindex expression or default expression, changing the session state is\\nblocked unless the session user also trusts the owners of those\\ntables.\\n\\nI see a few obvious objections to this line of attack that someone\\nmight raise, and I'd like to address them now. First, somebody might\\nargue that this is too hard to implement. I don't think so, because a\\nlot of things can be blocked from common locations. However, it will\\nbe necessary to go through all the functions we ship and add checks in\\na bunch of places to individual functions. That's a pain, but it's not\\nthat different from what we've already done with PARALLEL { SAFE |\\nRESTRICTED | UNSAFE } or LEAKPROOF. Those weren't terribly enjoyable\\nexercises for me and I made some mistakes categorizing some things,\\nbut the job got done and those mechanisms are accepted infrastructure\\nnow. Second, somebody might argue that full sandboxing is such a\\ndraconian set of restrictions that it will inconvenience users greatly\\nor that it's pointless to even allow anything to be executed or\\nsomething along those lines. I think that argument has some merit, but\\nI think the restrictions sound worse than they actually are in\\ncontext. For instance, have you ever written a default expression for\\na column that would fail under full sandboxing? I wouldn't be\\nsurprised if you have, but I also bet it's a fairly small percentage\\nof cases. I think a lot of things that people want to do as a\\npractical matter will be totally fine. I can think of exceptions, most\\nobviously reading from a random-number generator that has a\\nuser-controllable seed, which technically qualifies as tinkering with\\nthe session state. But a lot of things are going to work fine, and the\\nthings that do fall afoul of a mechanism like this probably deserve\\nsome study and examination. If you're writing index expressions that\\ndo anything more than simple calculation, it's probably fine for the\\nsystem to raise an eyebrow about that. Even if they do something as\\nsimple as reading from another table, that's not necessarily going to\\ndump and restore properly, even if it's secure, because the table\\nordering dependencies won't be clear to pg_dump.\\n\\nAnd that brings me to another point, which is that we might think of\\nsandboxing some operations, either by default or unconditionally, for\\nreasons other than trust or the lack of it. There's a lot of things\\nthat you COULD do in an index expression that you really SHOULD NOT\\ndo. As mentioned, even reading a table is pretty sketchy, but should a\\nfunction called from an index expression ever be allowed to execute\\nDDL? Is it reasonable if such a function wants to execute CREATE\\nTABLE? Even a temporary table is dubious, and a non-temporary table is\\nreally dubious. What if such a function wants to ALTER ROLE ...\\nSUPERUSER? I think that's bonkers and should almost certainly be\\ncategorically denied. Probably someone is trying to hack something,\\nand even if they aren't, it's still nuts. So I would argue that in a\\ncontext like an index expression, some amount of sandboxing -- not\\nnecessarily corresponding to either of the levels described above --\\nis probably a good idea, not based on the relationship between\\nwhatever users are involved, but based rather on the context. There's\\nroom for a lot of bikeshedding here and I don't think this kind of\\nthing is necessarily the top priority, but I think it's worth thinking\\nabout.\\n\\nFinally, I'd like to note that partial sandboxing can be viewed as a\\nstrengthening of restrictions that we already have in the form of\\nSECURITY_RESTRICTED_OPERATION. I can't claim to be an authority on the\\nevolution of that flag, but I think that up to this point the general\\nphilosophy has been to insert the smallest possible plug in the dike.\\nWhen a definite security problem is discovered, somebody tries to\\nblock just enough stuff to make it not demonstrably insecure. However,\\nI feel that the surface area for things to go wrong is rather large,\\nand we'd be better off with a more comprehensive series of\\nrestrictions. We likely have some security issues that haven't been\\nfound yet, and even something we wouldn't classify as a security\\nvulnerability can still be a pitfall for the unwary. I imagine that\\nSECURITY_RESTRICTED_OPERATION might end up getting subsumed into what\\nI'm here calling partial sandboxing, but I'm not quite sure about that\\nbecause right now this is just a theoretical description of a system,\\nnot something for which I've written any code.\\n\\nThanks,\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 31 Aug 2023 11:25:33 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"sandboxing untrusted code\"\n },\n {\n \"msg_contents\": \"On Thu, 2023-08-31 at 11:25 -0400, Robert Haas wrote:\\n> As a refresher, the scenario I'm talking about is any one in which\\n> one\\n> user, who I'll call Bob, does something that results in executing\\n> code\\n> provided by another user, who I'll call Alice. The most obvious way\\n> that this can happen is if Bob performs some operation that targets a\\n> table owned by Alice. That operation might be DML, like an INSERT or\\n> UPDATE; or it might be some other kind of maintenance command that\\n> can\\n> cause code execution, like REINDEX, which can evaluate index\\n> expressions.\\n\\nREINDEX executes index expressions as the table owner. (You are correct\\nthat INSERT executes index expressions as the inserting user.)\\n\\n> The code being executed might be run either as Alice or\\n> as Bob, depending on how it's been attached to the table and what\\n> operation is being performed and maybe whether some function or\\n> procedure that might contain it is SECURITY INVOKER or SECURITY\\n> DEFINER. Regardless of the details, our concern is that Alice's code\\n> might do something that Bob does not like. This is a particularly\\n> lively concern if the code happens to be running with the privileges\\n> of Bob, because then Alice might try to do something like access\\n> objects for which Bob has permissions and Alice does not.\\n\\nAgreed.\\n\\n\\n> 1. Compute stuff. There's no restriction on the permissible amount of\\n> compute; if you call untrusted code, nothing prevents it from running\\n> forever.\\n> 2. Call other code. This may be done by a function call or a command\\n> such as CALL or DO, all subject to the usual permissions checks but\\n> no\\n> further restrictions.\\n> 3. Access the current session state, without modifying it. For\\n> example, executing SHOW or current_setting() is fine.\\n> 4. Transiently modify the current session state in ways that are\\n> necessarily reversed before returning to the caller. For example, an\\n> EXCEPTION block or a configuration change driven by proconfig is\\n> fine.\\n> 5. Produce messages at any log level. This includes any kind of\\n> ERROR.\\n\\nNothing in that list really exercises privileges (except #2?). If those\\nare the allowed set of things a sandboxed function can do, is a\\nsandboxed function equivalent to a function running with no privileges\\nat all?\\n\\nPlease explain #2 in a bit more detail. Whose EXECUTE privileges would\\nbe used (I assume it depende on SECURITY DEFINER/INVOKER)? Would the\\ncalled code also be sandboxed?\\n\\n> In general if we have a great big call stack that involves calling a\\n> whole bunch of functions either as SECURITY INVOKER or as SECURITY\\n> DEFINER, changing the session state is blocked unless the session\\n> user\\n> trusts the owners of all of those functions.\\n\\nThat clarifies the earlier mechanics you described, thank you.\\n\\n> And if we got to any of\\n> those functions by means of code attached directly to tables, like an\\n> index expression or default expression, changing the session state is\\n> blocked unless the session user also trusts the owners of those\\n> tables.\\n> \\n> I see a few obvious objections to this line of attack that someone\\n> might raise, and I'd like to address them now. First, somebody might\\n> argue that this is too hard to implement.\\n\\nThat seems to be a response to my question above: \\\"Isn't that a hard\\nproblem; maybe impossible?\\\".\\n\\nLet me qualify that: if the function is written by Alice, and the code\\nis able to really exercise the privileges of the caller (Bob), then it\\nseems really hard to make it safe for the caller.\\n\\nIf the function is sandboxed such that it's not really using Bob's\\nprivileges (it's just nominally running as Bob) that's a much more\\ntractable problem.\\n\\nI believe there's some nuance to your proposal where some of Bob's\\nprivileges could be used safely, but I'm not clear on exactly which\\nones. The difficulty of the implementation would depend on these\\ndetails.\\n\\n> Second, somebody might argue that full sandboxing is such a\\n> draconian set of restrictions that it will inconvenience users\\n> greatly\\n> or that it's pointless to even allow anything to be executed or\\n> something along those lines. I think that argument has some merit,\\n> but\\n> I think the restrictions sound worse than they actually are in\\n> context.\\n\\n+100. We should make typical cases easy to secure.\\n\\n> Even if they do something as\\n> simple as reading from another table, that's not necessarily going to\\n> dump and restore properly, even if it's secure, because the table\\n> ordering dependencies won't be clear to pg_dump.\\n\\nA good point. A lot of these extraordinary cases are either incredibly\\nfragile or already broken.\\n\\n> What if such a function wants to ALTER ROLE ...\\n> SUPERUSER? I think that's bonkers and should almost certainly be\\n> categorically denied.\\n\\n...also agreed, a lot of these extraordinary cases are really just\\nsurface area for attack with no legitimate use case.\\n\\n\\n\\n\\nOne complaint (not an objection, because I don't think we have\\nthe luxury of objecting to viable proposals when it comes to improving\\nour security model):\\n\\nAlthough your proposal sounds like a good security backstop, it feels\\nlike it's missing the point that there are different _kinds_ of\\nfunctions. We already have the IMMUTABLE marker and we already have\\nruntime checks to make sure that immutable functions can't CREATE\\nTABLE; why not build on that mechanism or create new markers?\\n\\nDeclarative markers are nice because they are easier to test: if Alice\\nwrites a function and declares it as IMMUTABLE, she can test it before\\neven using it in an index expression and it will fail whatever runtime\\nprotections IMMUTABLE offers. If we instead base it on the session user\\nand call stack, Alice wouldn't be able to test it effectively, only Bob\\ncan test it.\\n\\nIn other words, there are some consistency aspects to how we run code\\nthat go beyond pure security. A function author typically has\\nassumptions about the execution context of a function (the user, the\\nsandbox restrictions, the search_path, etc.) and guiding users towards\\na consistent execution context in typical cases is a good thing.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 31 Aug 2023 17:57:25 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: sandboxing untrusted code\"\n },\n {\n \"msg_contents\": \"On Thu, Aug 31, 2023 at 8:57 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > As a refresher, the scenario I'm talking about is any one in which\\n> > one\\n> > user, who I'll call Bob, does something that results in executing\\n> > code\\n> > provided by another user, who I'll call Alice. The most obvious way\\n> > that this can happen is if Bob performs some operation that targets a\\n> > table owned by Alice. That operation might be DML, like an INSERT or\\n> > UPDATE; or it might be some other kind of maintenance command that\\n> > can\\n> > cause code execution, like REINDEX, which can evaluate index\\n> > expressions.\\n>\\n> REINDEX executes index expressions as the table owner. (You are correct\\n> that INSERT executes index expressions as the inserting user.)\\n\\nI was speaking here of who provided the code, rather than whose\\ncredentials were used to execute it. The index expressions are\\nprovided by the table owner no matter who evaluates them in a\\nparticular case.\\n\\n> > 1. Compute stuff. There's no restriction on the permissible amount of\\n> > compute; if you call untrusted code, nothing prevents it from running\\n> > forever.\\n> > 2. Call other code. This may be done by a function call or a command\\n> > such as CALL or DO, all subject to the usual permissions checks but\\n> > no\\n> > further restrictions.\\n> > 3. Access the current session state, without modifying it. For\\n> > example, executing SHOW or current_setting() is fine.\\n> > 4. Transiently modify the current session state in ways that are\\n> > necessarily reversed before returning to the caller. For example, an\\n> > EXCEPTION block or a configuration change driven by proconfig is\\n> > fine.\\n> > 5. Produce messages at any log level. This includes any kind of\\n> > ERROR.\\n>\\n> Nothing in that list really exercises privileges (except #2?). If those\\n> are the allowed set of things a sandboxed function can do, is a\\n> sandboxed function equivalent to a function running with no privileges\\n> at all?\\n\\nClose but not quite. As you say, #2 does exercise privileges. Also,\\neven if no privileges are exercised, you could still refer to\\nCURRENT_ROLE, and I think you could also call a function like\\nhas_table_privilege. Your identity hasn't changed, but you're\\nrestricted from exercising some of your privileges. Really, you still\\nhave them, but they're just not available to you in that situation.\\n\\n> Please explain #2 in a bit more detail. Whose EXECUTE privileges would\\n> be used (I assume it depende on SECURITY DEFINER/INVOKER)? Would the\\n> called code also be sandboxed?\\n\\nNothing in this proposed system has any impact on whose privileges are\\nused in any particular context, so any privilege checks conducted\\npursuant to #2 are performed as the same user who would perform them\\ntoday. Whether the called code would be sandboxed depends on how the\\nrules I articulated in the previous email would apply to it. Since\\nthose rules depend on the user IDs, if the called code is owned by the\\nsame user as the calling code and is SECURITY INVOKER, then those\\nrules apply in the same way and the same level of sandboxing will\\napply. But if the called function is owned by a different user or is\\nSECURITY DEFINER, then the rules might apply differently to the called\\ncode than the calling code. It's possible this isn't quite good enough\\nand that some adjustments to the rules are necessary; I'm not sure.\\n\\n> Let me qualify that: if the function is written by Alice, and the code\\n> is able to really exercise the privileges of the caller (Bob), then it\\n> seems really hard to make it safe for the caller.\\n>\\n> If the function is sandboxed such that it's not really using Bob's\\n> privileges (it's just nominally running as Bob) that's a much more\\n> tractable problem.\\n\\nAgreed.\\n\\n> One complaint (not an objection, because I don't think we have\\n> the luxury of objecting to viable proposals when it comes to improving\\n> our security model):\\n>\\n> Although your proposal sounds like a good security backstop, it feels\\n> like it's missing the point that there are different _kinds_ of\\n> functions. We already have the IMMUTABLE marker and we already have\\n> runtime checks to make sure that immutable functions can't CREATE\\n> TABLE; why not build on that mechanism or create new markers?\\n\\nI haven't ruled that out completely, but there's some subtlety here\\nthat doesn't exist in those other cases. If the owner of a function\\nmarks it wrongly in terms of volatility or parallel safety, then they\\nmight make queries run more slowly than they should, or they might\\nmake queries return wrong answers, or error out, or even end up with\\nmessed-up indexes. But none of that threatens the stability of the\\nsystem in any very deep way, or the security of the system. It's no\\ndifferent than putting a CHECK (false) constraint on a table, or\\nsomething like that: it might make the system not work, and if that\\nhappens, then you can fix it. Here, however, we can't trust the owners\\nof functions to label those functions accurately. It won't do for\\nAlice to create a function and then apply the NICE_AND_SAFE marker to\\nit. That defeats the whole point. We need to know the real behavior of\\nAlice's function, not the behavior that Alice says it has.\\n\\nNow, in the case of a C function, things are a bit different. We can't\\ninspect the generated machine code and know what the function does,\\nbecause of that pesky halting problem. We could handle that either\\nthrough function labeling, since only superusers can create C\\nfunctions, or by putting checks directly in the C code. I was somewhat\\ninclined toward the latter approach, but I'm not completely sure yet\\nwhat makes sense. Thinking about your comments here made me realize\\nthat there are other procedural languages to worry about, too, like\\nPL/python or PL/perl or PL/sh. Whatever we do for the C functions will\\nhave to be extended to those cases somehow as well. If we label\\nfunctions, then we'll have to allow superusers only to label functions\\nin these languages as well and make the default label \\\"this is\\nunsafe.\\\" If we put checks in the C code then I guess any given PL\\nneeds to certify that it knows about sandboxing or have all of its\\nfunctions treated as unsafe. I think doing this at the C level would\\nbe better, strictly speaking, because it's more granular. Imagine a\\nfunction that only conditionally does some prohibited action - it can\\nbe allowed to work in the cases where it does not attempt the\\nprohibited operation, and blocked when it does. Labeling is\\nall-or-nothing.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 1 Sep 2023 09:12:22 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: sandboxing untrusted code\"\n },\n {\n \"msg_contents\": \"On Fri, 2023-09-01 at 09:12 -0400, Robert Haas wrote:\\n> Close but not quite. As you say, #2 does exercise privileges. Also,\\n> even if no privileges are exercised, you could still refer to\\n> CURRENT_ROLE, and I think you could also call a function like\\n> has_table_privilege. Your identity hasn't changed, but you're\\n> restricted from exercising some of your privileges. Really, you still\\n> have them, but they're just not available to you in that situation.\\n\\nWhich privileges are available in a sandboxed environment, exactly? Is\\nit kind of like masking away all privileges except EXECUTE, or are\\nother privileges available, like SELECT?\\n\\nAnd the distinction that you are drawing between having the privileges\\nbut them (mostly) not being available, versus not having the privileges\\nat all, is fairly subtle. Some examples showing why that distinction is\\nimportant would be helpful.\\n\\n> \\n> > Although your proposal sounds like a good security backstop, it\\n> > feels\\n> > like it's missing the point that there are different _kinds_ of\\n> > functions. We already have the IMMUTABLE marker and we already have\\n> > runtime checks to make sure that immutable functions can't CREATE\\n> > TABLE; why not build on that mechanism or create new markers?\\n\\n...\\n\\n> Here, however, we can't trust the owners\\n> of functions to label those functions accurately.\\n\\nOf course, but observe:\\n\\n =# CREATE FUNCTION f(i INT) RETURNS INT IMMUTABLE LANGUAGE plpgsql AS\\n $$\\n BEGIN\\n CREATE TABLE x(t TEXT);\\n RETURN 42 + i;\\n END;\\n $$;\\n\\n =# SELECT f(2);\\n ERROR: CREATE TABLE is not allowed in a non-volatile function\\n CONTEXT: SQL statement \\\"CREATE TABLE x(t TEXT)\\\"\\n PL/pgSQL function f(integer) line 3 at SQL statement\\n\\nThe function f() is called at the top level, not as part of any index\\nexpression or other special context. But it fails to CREATE TABLE\\nsimply because that's not an allowed thing for an IMMUTABLE function to\\ndo. That tells me right away that my function isn't going to work, and\\nI can rewrite it rather than waiting for some other user to say that it\\nfailed when run in a sandbox.\\n\\n> It won't do for\\n> Alice to create a function and then apply the NICE_AND_SAFE marker to\\n> it.\\n\\nYou can if you always execute NICE_AND_SAFE functions in a sandbox. The\\ndifference is that it's always executed in a sandbox, rather than\\nsometimes, so it will fail consistently.\\n\\n> Now, in the case of a C function, things are a bit different. We\\n> can't\\n> inspect the generated machine code and know what the function does,\\n> because of that pesky halting problem. We could handle that either\\n> through function labeling, since only superusers can create C\\n> functions, or by putting checks directly in the C code. I was\\n> somewhat\\n> inclined toward the latter approach, but I'm not completely sure yet\\n> what makes sense. Thinking about your comments here made me realize\\n> that there are other procedural languages to worry about, too, like\\n> PL/python or PL/perl or PL/sh. Whatever we do for the C functions\\n> will\\n> have to be extended to those cases somehow as well. If we label\\n> functions, then we'll have to allow superusers only to label\\n> functions\\n> in these languages as well and make the default label \\\"this is\\n> unsafe.\\\" If we put checks in the C code then I guess any given PL\\n> needs to certify that it knows about sandboxing or have all of its\\n> functions treated as unsafe. I think doing this at the C level would\\n> be better, strictly speaking, because it's more granular. Imagine a\\n> function that only conditionally does some prohibited action - it can\\n> be allowed to work in the cases where it does not attempt the\\n> prohibited operation, and blocked when it does. Labeling is\\n> all-or-nothing.\\n\\nHere I'm getting a little lost in what you mean by \\\"prohibited\\noperation\\\". Most languages mostly use SPI, and whatever sandboxing\\nchecks you do should work there, too. Are you talking about completely\\nseparate side effects like writing files or opening sockets?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 01 Sep 2023 14:27:07 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: sandboxing untrusted code\"\n },\n {\n \"msg_contents\": \"On Fri, Sep 1, 2023 at 5:27 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> Which privileges are available in a sandboxed environment, exactly? Is\\n> it kind of like masking away all privileges except EXECUTE, or are\\n> other privileges available, like SELECT?\\n\\nI think I've more or less answered this already -- fully sandboxed\\ncode can't make reference to external data sources, from which it\\nfollows that it can't exercise SELECT (and most other privileges).\\n\\n> And the distinction that you are drawing between having the privileges\\n> but them (mostly) not being available, versus not having the privileges\\n> at all, is fairly subtle. Some examples showing why that distinction is\\n> important would be helpful.\\n\\nI view it like this: when Bob tries to insert or update or delete\\nAlice's table, and Alice has some code attached to it, Alice is\\neffectively asking Bob to execute that code with his own privileges.\\nIn general, I think we can reasonably expect that Bob WILL be willing\\nto do this: if he didn't want to modify into Alice's table, he\\nwouldn't have executed a DML statement against it, and executing the\\ncode that Alice has attached to that table is a precondition of being\\nallowed to perform that modification. It's Alice's table and she gets\\nto set the rules. However, Bob is also allowed to protect himself. If\\nhe's running Alice's code and it wants to do something with which Bob\\nisn't comfortable, he can change his mind and refuse to execute it\\nafter all.\\n\\nI always find it helpful to consider real world examples with similar\\ncharacteristics. Let's say that Bob is renting a VRBO from Alice.\\nAlice leaves behind, in the VRBO, a set of rules which Bob must follow\\nas a condition of being allowed to rent the VRBO. Those rules include\\nthings that Bob but must do at checkout time, like washing all of his\\ndishes. As a matter of routine, Bob will follow Alice's checkout\\ninstructions. But if Alice includes in the checkout instructions\\n\\\"Leave your driver's license and social security card on the dining\\nroom table after checkout, plus a record of all of your bank account\\nnumbers,\\\" the security systems in Bob's brain should activate and\\nprevent those instructions from getting followed.\\n\\nA major difference between that situation (a short term rental of\\nsomeone else's house) and the in-database case (a DML statement\\nagainst someone else's table) is that when Bob is following Alice's\\nVRBO checkout instructions, he knows exactly what actions he is\\nperforming. When he executes a DML statement against Alice's table,\\nBob the human being does not actually know what Alice's triggers or\\nindex expressions or whatever are causing him to do. As I see it, the\\npurpose of this system is to prevent Bob from doing things that he\\ndidn't intend to do. He's cool with adding 2 and 2 or concatenating\\nsome strings or whatever, but probably not with reading data and\\nhanding it over to Alice, and definitely not handing all of his\\nprivileges over to Alice. Full sandboxing has to block that kind of\\nstuff, and it needs to do so precisely because *Bob would not allow\\nthose operations if he knew about them*.\\n\\nNow, it is not going to be possible to get that perfectly right.\\nPostgreSQL can not know the state of Bob's human mind, and it cannot\\nbe expected to judge with perfect accuracy what actions Bob would or\\nwould not approve. However, it can make some conservative guesses. If\\nBob wants to override those guesses by saying \\\"I trust Alice, do\\nwhatever she says\\\" that's fine. This system attempts to prevent Bob\\nfrom accidentally giving away his permissions to an adversary who has\\nburied malicious code in some unexpected place. But, unlike the\\nregular permissions system, it is not there to prevent Bob from doing\\nthings that he isn't allowed to do. It's there to prevent Bob from\\ndoing things that he didn't intend to do.\\n\\nAnd that's where I see the distinction between *having* permissions\\nand those permissions being *available* in a particular context. Bob\\nhas permission to give Alice an extra $1000 or whatever if he has the\\nmoney and wishes to do so. But those permissions are probably not\\n*available* in the context where Bob is following a set of\\ninstructions from Alice. If Bob's brain spontaneously generated the\\nidea \\\"let's give Alice a $1000 tip because her vacation home was\\nabsolutely amazing and I am quite rich,\\\" he would probably go right\\nahead and act on that idea and that is completely fine. But when Bob\\nencounters that same idea *on a list of instructions provided by\\nAlice*, the same operation is blocked *because it came from Alice*. If\\nthe list of instructions from Alice said to sweep the parlor, Bob\\nwould just go ahead and do it. Alice has permission to induce Bob to\\nsweep the parlor, but does not have permission to induce Bob to give\\nher a bunch of extra money.\\n\\nAnd in the database context, I think it's fine if Alice induces Bob to\\ncompute some values or look at the value of work_mem, but I don't\\nthink it's OK if Alice induces Bob to make her a superuser. Unless Bob\\ndeclares that he trusts Alice completely, in which case it's fine if\\nshe does that.\\n\\n> Here I'm getting a little lost in what you mean by \\\"prohibited\\n> operation\\\". Most languages mostly use SPI, and whatever sandboxing\\n> checks you do should work there, too. Are you talking about completely\\n> separate side effects like writing files or opening sockets?\\n\\nYeah.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 5 Sep 2023 12:25:28 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: sandboxing untrusted code\"\n },\n {\n \"msg_contents\": \"On Tue, 2023-09-05 at 12:25 -0400, Robert Haas wrote:\\n> I think I've more or less answered this already -- fully sandboxed\\n> code can't make reference to external data sources, from which it\\n> follows that it can't exercise SELECT (and most other privileges).\\n\\nBy what principle are we allowing EXECUTE but not SELECT? In theory, at\\nleast, a function could hold secrets in the code, e.g.:\\n\\n CREATE FUNCTION answer_to_ultimate_question() RETURNS INT\\n LANGUAGE plpgsql AS $$ BEGIN RETURN 42; END; $$;\\n\\nObviously that's a bad idea in plpgsql, because anyone can just read\\npg_proc. And maybe C would be handled differently somehow, so maybe it\\nall works.\\n\\nBut it feels like something is wrong there: it's fine to execute the\\nanswer_to_ultimate_question() not because Bob has an EXECUTE privilege,\\nbut because the sandbox renders any security concerns with *anyone*\\nexecuting the function moot. So why bother checking the EXECUTE\\nprivilege at all?\\n\\n> And that's where I see the distinction between *having* permissions\\n> and those permissions being *available* in a particular context. Bob\\n> has permission to give Alice an extra $1000 or whatever if he has the\\n> money and wishes to do so. But those permissions are probably not\\n> *available* in the context where Bob is following a set of\\n> instructions from Alice. If Bob's brain spontaneously generated the\\n> idea \\\"let's give Alice a $1000 tip because her vacation home was\\n> absolutely amazing and I am quite rich,\\\" he would probably go right\\n> ahead and act on that idea and that is completely fine. But when Bob\\n> encounters that same idea *on a list of instructions provided by\\n> Alice*, the same operation is blocked *because it came from Alice*.\\n> If\\n> the list of instructions from Alice said to sweep the parlor, Bob\\n> would just go ahead and do it. Alice has permission to induce Bob to\\n> sweep the parlor, but does not have permission to induce Bob to give\\n> her a bunch of extra money.\\n\\nIn the real world example, sweeping the parlor has a (slight) cost to\\nthe person doing it and it (slightly) matters who does it. In Postgres,\\nwe don't do any CPU accounting per user, and it's all executed under\\nthe same PID, so it really doesn't matter.\\n\\nSo it raises the question: why would we not simply say that this list\\nof instructions should be executed by the person who wrote it, in which\\ncase the existing privilege mechanism would work just fine?\\n\\n> And in the database context, I think it's fine if Alice induces Bob\\n> to\\n> compute some values or look at the value of work_mem, but I don't\\n> think it's OK if Alice induces Bob to make her a superuser.\\n\\nIf all the code can do is compute some values or look at work_mem,\\nperhaps the function needs no privileges at all (or some minimal\\nprivileges)?\\n\\nYou explained conceptually where you're coming from, but I still don't\\nsee much of a practical difference between having privileges but being\\nin a context where they won't be used, and dropping the privileges\\nentirely during that time. I suppose the answer is that the EXECUTE\\nprivilege will still be used, but as I said above, that doesn't\\nentirely make sense to me, either.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 05 Sep 2023 15:20:53 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: sandboxing untrusted code\"\n }\n]","isConversational":false}}},{"rowIdx":52974,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\n\nI wonder if we really need signals to implement interrupts. Given\nthat they are non-preemptive/cooperative (work happens at the next\nCFI()), why not just use shared memory flags and latches? That skips\na bunch of code, global variables and scary warnings about programming\nin signal handlers.\n\nI sketched out some code to try that a few months back, while\nspeculating about bite-sized subproblems that would come up if each\nbackend is, one day, a thread.\n\nThere are several other conditions that are also handled by\nCHECK_FOR_INTERRUPTS(), but are not triggered by other backends\nsending signals, or are set by other signal handlers (SIGALRM,\nSIGQUIT). One idea is to convert those into \"procsignals\" too, for\nconsistency. In the attached, they can be set (ie by the same\nbackend) with ProcSignalRaise(), but it's possible that in future we\nmight have a reason for another backend to set them too, so it seems\nlike a good idea to have a single system, effectively merging the\nconcepts of \"procsignals\" and \"interrupts\".\n\nThere are still a few more ad hoc (non-ProcSignal) uses of SIGUSR1 in\nthe tree. For one thing, we don't allow the postmaster to set\nlatches; if we gave up on that rule, we wouldn't need the bgworker\nplease-signal-me thing. Also the logical replication launcher does\nthe same sort of thing for no apparent reason. Changed in the\nattached -- mainly so I could demonstrate that check-world passes with\nSIGUSR1 ignored.\n\nThe attached is only experiment grade code: in particular, I didn't\nquite untangle the recovery conflict flags properly. It's also doing\nfunction calls where some kind of fast inlined magic is probably\nrequired, and I probably have a few other details wrong, but I figured\nit was good enough to demonstrate the concept.","msg_date":"Thu, 21 Oct 2021 07:55:54 +1300","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Interrupts vs signals"},{"msg_contents":"Hi,\n\nOn 2021-10-21 07:55:54 +1300, Thomas Munro wrote:\n> I wonder if we really need signals to implement interrupts. Given\n> that they are non-preemptive/cooperative (work happens at the next\n> CFI()), why not just use shared memory flags and latches? That skips\n> a bunch of code, global variables and scary warnings about programming\n> in signal handlers.\n\nDepending on how you implement them, one difference could be whether / when\n\"slow\" system calls (recv, poll, etc) are interrupted.\n\nAnother is that that signal handling provides a memory barrier in the\nreceiving process. For things that rarely change (like most interrupts), it\ncan be more efficient to move the cost of that out-of-line, instead of\nincurring them on every check.\n\n\nOne nice thing of putting the state variables into shared memory would be that\nthat'd allow to see the pending interrupts of other backends for debugging\npurposes.\n\n\n> One idea is to convert those into \"procsignals\" too, for\n> consistency. In the attached, they can be set (ie by the same\n> backend) with ProcSignalRaise(), but it's possible that in future we\n> might have a reason for another backend to set them too, so it seems\n> like a good idea to have a single system, effectively merging the\n> concepts of \"procsignals\" and \"interrupts\".\n\nThis seems a bit confusing to me. For one, we need to have interrupts working\nbefore we have a proc, IIRC. But leaving details like that aside, it just\nseems a bit backwards to me. I'm on board with other backends directly setting\ninterrupt flags, but it seems to me that the procsignal stuff should be\n\"client\" of the process-local interrupt infrastructure, rather than the other\nway round.\n\n\n> +bool\n> +ProcSignalAnyPending(void)\n> +{\n> +\tvolatile ProcSignalSlot *slot = MyProcSignalSlot;\n> \n> -\tif (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))\n> -\t\tRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);\n> +\t/* XXX make this static inline? */\n> +\t/* XXX point to a dummy entry instead of using NULL to avoid a branch */\n> +\treturn slot && slot->pss_signaled;\n> +}\n\nISTM it might be easier to make this stuff efficiently race-free if we made\nthis a count of pending operations.\n\n\n> @@ -3131,12 +3124,13 @@ ProcessInterrupts(void)\n> \t/* OK to accept any interrupts now? */\n> \tif (InterruptHoldoffCount != 0 || CritSectionCount != 0)\n> \t\treturn;\n> -\tInterruptPending = false;\n> +\tProcSignalClearAnyPending();\n> +\n> +\tpg_read_barrier();\n> \n> -\tif (ProcDiePending)\n> +\tif (ProcSignalConsume(PROCSIG_DIE))\n> \t{\n\nI think making all of these checks into function calls isn't great. How about\nmaking the set of pending signals a bitmask? That'd allow to efficiently check\na bunch of interrupts together and even where not, it'd just be a single test\nof the mask, likely already in a register.\n\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Wed, 20 Oct 2021 12:27:48 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Thu, Oct 21, 2021 at 8:27 AM Andres Freund <andres@anarazel.de> wrote:\n> On 2021-10-21 07:55:54 +1300, Thomas Munro wrote:\n> > I wonder if we really need signals to implement interrupts. Given\n> > that they are non-preemptive/cooperative (work happens at the next\n> > CFI()), why not just use shared memory flags and latches? That skips\n> > a bunch of code, global variables and scary warnings about programming\n> > in signal handlers.\n>\n> Depending on how you implement them, one difference could be whether / when\n> \"slow\" system calls (recv, poll, etc) are interrupted.\n\nHopefully by now all such waits are implemented with latch.c facilities?\n\n> Another is that that signal handling provides a memory barrier in the\n> receiving process. For things that rarely change (like most interrupts), it\n> can be more efficient to move the cost of that out-of-line, instead of\n> incurring them on every check.\n\nAgreed, but in this experiment I was trying out the idea that a memory\nbarrier is not really needed at all, unless you're about to go to\nsleep. We already insert one of those before a latch wait. That is,\nif we see !set->latch->is_set, we do pg_memory_barrier() and check\nagain, before sleeping, so your next CFI must see the flag. For\ncomputation loops (sort, hash, query execution, ...), I speculate that\na relaxed read of memory is fine... you'll see the flag pretty soon,\nand you certainly won't be allowed to finish your computation and go\nto sleep.\n\n> One nice thing of putting the state variables into shared memory would be that\n> that'd allow to see the pending interrupts of other backends for debugging\n> purposes.\n\n+1\n\n> > One idea is to convert those into \"procsignals\" too, for\n> > consistency. In the attached, they can be set (ie by the same\n> > backend) with ProcSignalRaise(), but it's possible that in future we\n> > might have a reason for another backend to set them too, so it seems\n> > like a good idea to have a single system, effectively merging the\n> > concepts of \"procsignals\" and \"interrupts\".\n>\n> This seems a bit confusing to me. For one, we need to have interrupts working\n> before we have a proc, IIRC. But leaving details like that aside, it just\n> seems a bit backwards to me. I'm on board with other backends directly setting\n> interrupt flags, but it seems to me that the procsignal stuff should be\n> \"client\" of the process-local interrupt infrastructure, rather than the other\n> way round.\n\nHmm. Yeah, I see your point. But I can also think of some arguments\nfor merging the concepts of local and shared interrupts; see below.\n\nIn this new sketch, I tried doing it the other way around. That is,\ncompletely removing the concept of \"ProcSignal\", leaving only\n\"Interrupts\". Initially, MyPendingInterrupts points to something\nprivate, and once you're connected to shared memory it points to\nMyProc->pending_interrupts.\n\n> > +bool\n> > +ProcSignalAnyPending(void)\n> > +{\n> > + volatile ProcSignalSlot *slot = MyProcSignalSlot;\n> >\n> > - if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))\n> > - RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);\n> > + /* XXX make this static inline? */\n> > + /* XXX point to a dummy entry instead of using NULL to avoid a branch */\n> > + return slot && slot->pss_signaled;\n> > +}\n>\n> ISTM it might be easier to make this stuff efficiently race-free if we made\n> this a count of pending operations.\n\nHmm, with a unified interrupt system and a bitmap it's not necessary\nto have a separate flag/counter at all.\n\n> > @@ -3131,12 +3124,13 @@ ProcessInterrupts(void)\n> > /* OK to accept any interrupts now? */\n> > if (InterruptHoldoffCount != 0 || CritSectionCount != 0)\n> > return;\n> > - InterruptPending = false;\n> > + ProcSignalClearAnyPending();\n> > +\n> > + pg_read_barrier();\n> >\n> > - if (ProcDiePending)\n> > + if (ProcSignalConsume(PROCSIG_DIE))\n> > {\n>\n> I think making all of these checks into function calls isn't great. How about\n> making the set of pending signals a bitmask? That'd allow to efficiently check\n> a bunch of interrupts together and even where not, it'd just be a single test\n> of the mask, likely already in a register.\n\n+1.\n\nSome assorted notes:\n\n1. Aside from doing interrupts in this new way, I also have the\npostmaster setting latches (!) instead of sending ad hoc SIGUSR1 here\nand there. My main reason for doing that was to be able to chase out\nall reasons to register a SIGUSR1 handler, so I could prove that\ncheck-world passes. I like it, though. But maybe it's really a\nseparate topic.\n\n2. I moved this stuff into interrupt.{h,c}. There is nothing left in\nprocsignal.c except code relating to ProcSignalBarrier. I guess that\nthing could use another name, anyway. It's a ...\nSystemInterruptBarrier?\n\n3. Child-level SIGINT and SIGTERM handlers probably aren't really\nnecessary, either: maybe the sender could do\nInterruptSend(INTERRUPT_{DIE,QUERY_CANCEL}, pgprocno) instead? But\nperhaps people are attached to being able to send those signals from\nexternal programs directly to backends.\n\n4. Like the above, a SIGALRM handler might need to do eg\nInterruptRaise(INTERRUPT_STATEMENT_TIMEOUT). That's a problem for\nsystems using spinlocks (self-deadlock against user context in\nInterruptRaise()), so I'd need to come up with some flag protocol for\ndinosaurs to make that safe, OR revert to having these \"local only\"\ninterrupts done with separate flags, as you were getting at earlier.\n\n5. The reason I prefer to put currently \"local only\" interrupts into\nthe same atomic system is that I speculate that ultimately all of the\nbackend-level signal handlers won't be needed. They all fall into\nthree categories: (1) could be replaced with these interrupts\ndirectly, (2) could be replaced by the new timer infrastructure that\nmultithreaded postgres would need to have to deliver interrupts to the\nright recipients, (3) are quickdie and can be handled at the\ncontaining process level. Then the only signal handlers left are top\nlevel external ones.\n\nBut perhaps you're right and I should try reintroducing separate local\ninterrupts for now. I dunno, I like the simplicity of the unified\nsystem; if only it weren't for those spinlock-backed atomics.","msg_date":"Thu, 11 Nov 2021 18:27:09 +1300","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Thu, Nov 11, 2021 at 12:27 AM Thomas Munro <thomas.munro@gmail.com> wrote:\n> > Depending on how you implement them, one difference could be whether / when\n> > \"slow\" system calls (recv, poll, etc) are interrupted.\n>\n> Hopefully by now all such waits are implemented with latch.c facilities?\n\nDo read(), write(), etc. count? Because we certainly have raw calls to\nthose functions in lots of places.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 11 Nov 2021 09:06:01 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"Hi,\n\nOn 2021-11-11 09:06:01 -0500, Robert Haas wrote:\n> On Thu, Nov 11, 2021 at 12:27 AM Thomas Munro <thomas.munro@gmail.com> wrote:\n> > > Depending on how you implement them, one difference could be whether / when\n> > > \"slow\" system calls (recv, poll, etc) are interrupted.\n> >\n> > Hopefully by now all such waits are implemented with latch.c facilities?\n> \n> Do read(), write(), etc. count? Because we certainly have raw calls to\n> those functions in lots of places.\n\nThey can count, but only when used for network sockets or pipes (\"slow\ndevices\" or whatever the posix language is). Disk IO doesn't count as that. So\nI don't think it'd be a huge issue.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 11 Nov 2021 11:50:00 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Thu, Nov 11, 2021 at 2:50 PM Andres Freund <andres@anarazel.de> wrote:\n> They can count, but only when used for network sockets or pipes (\"slow\n> devices\" or whatever the posix language is). Disk IO doesn't count as that. So\n> I don't think it'd be a huge issue.\n\nSomehow the idea that the network is a slow device and the disk a fast\none does not seem like it's necessarily accurate on modern hardware,\nbut I guess the spec is what it is.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 11 Nov 2021 15:24:41 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Fri, Nov 12, 2021 at 9:24 AM Robert Haas <robertmhaas@gmail.com> wrote:\n> On Thu, Nov 11, 2021 at 2:50 PM Andres Freund <andres@anarazel.de> wrote:\n> > They can count, but only when used for network sockets or pipes (\"slow\n> > devices\" or whatever the posix language is). Disk IO doesn't count as that. So\n> > I don't think it'd be a huge issue.\n>\n> Somehow the idea that the network is a slow device and the disk a fast\n> one does not seem like it's necessarily accurate on modern hardware,\n> but I guess the spec is what it is.\n\n[Somehow I managed to reply to Robert only; let me try that again,\nthis time to the list...]\n\nNetwork filesystems have in the past been confusing because they're\nboth disk-like and network-like, and also slow as !@#$, which is why\nthere have been mount point options like \"intr\", \"nointr\" (now ignored\non Linux) to control what happens if you receive an async signal\nduring a sleepy read/write. But even if you had some kind of\nDeathstation 9000 that had a switch on the front panel that ignores\nSA_RESTART and produces EINTR for disk I/O when a signal arrives,\nPostgreSQL already doesn't work today. Our pread() and pwrite() paths\nfor data and WAL don't not have a EINTR loops or\nCHECK_FOR_INTERRUPTS() (we just can't take interrupts in the middle of\neg a synchronous write), so I think we'd produce an ERROR or PANIC.\nSo I think disk I/O is irrelevant, and network/pipe I/O is already\nhandled everywhere via latch.c facilities.\n\nIf there are any eg blocking reads on a socket in PostgreSQL, we\nshould fix that to use latch.c non-blocking techniques, because such a\nplace is already a place that ignores postmaster death and interrupts.\nTo be more precise: such a place could of course wake up for EINTR on\nSIGUSR1 from procsignal.c, and that would no longer happen with my\npatch, but if we're relying on that anywhere, it's dangerous and\nunreliable. If SIGUSR1 is delivered right before you enter a blocking\nread(), you'll sleep waiting for the socket or whatever. That's\nprecisely the problem that latch.c solves, and why it's already a bug\nif there are such places.\n\n\n","msg_date":"Fri, 12 Nov 2021 09:57:38 +1300","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"Here's an updated version of this patch.\n\nThe main idea is that SendProcSignal(pid, PROCSIGNAL_XXX, procno)\nbecomes SendInterrupt(INTERRUPT_XXX, procno), and all the pending\ninterrupt global variables and pss_procsignalFlags[] go away, along\nwith the SIGUSR1 handler. The interrupts are compressed into a single\nbitmap. See commit message for more details.\n\nThe patch is failing on Windows CI for reasons I haven't debugged yet,\nbut I wanted to share what I have so far. Work in progress!\n\nHere is my attempt to survey the use of signals and write down what I\nthink we might do about them all so far, to give the context for this\npatch:\n\nhttps://wiki.postgresql.org/wiki/Signals\n\nComments, corrections, edits very welcome.","msg_date":"Mon, 8 Jul 2024 14:56:38 +1200","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 08/07/2024 05:56, Thomas Munro wrote:\n> Here's an updated version of this patch.\n> \n> The main idea is that SendProcSignal(pid, PROCSIGNAL_XXX, procno)\n> becomes SendInterrupt(INTERRUPT_XXX, procno), and all the pending\n> interrupt global variables and pss_procsignalFlags[] go away, along\n> with the SIGUSR1 handler. The interrupts are compressed into a single\n> bitmap. See commit message for more details.\n> \n> The patch is failing on Windows CI for reasons I haven't debugged yet,\n> but I wanted to share what I have so far. Work in progress!\n> \n> Here is my attempt to survey the use of signals and write down what I\n> think we might do about them all so far, to give the context for this\n> patch:\n> \n> https://wiki.postgresql.org/wiki/Signals\n> \n> Comments, corrections, edits very welcome.\n\nNice, thanks!\n\n> Background worker state notifications are also changed from raw\n> kill(SIGUSR1) to SetLatch(). That means that SetLatch() is now called\n> from the postmaster. The main purpose of including that change is to be\n> able to remove procsignal_sigusr1_handler completely and set SIGUSR1 to\n> SIG_IGN, and show the system working.\n> \n> XXX Do we need to invent SetLatchRobust() that doesn't trust anything in\n> shared memory, to be able to set latches from the postmaster?\n\nThe patch actually does both: it still does kill(SIGUSR1) and also sets \nthe latch.\n\nI think it would be nice if RegisterDynamicBackgroundWorker() had a \n\"bool notify_me\" argument, instead of requiring the caller to set \n\"bgw_notify_pid = MyProcPid\" before the call. That's a \nbackwards-compatibility break, but maybe we should bite the bullet and \ndo it. Or we could do this in RegisterDynamicBackgroundWorker():\n\nif (worker->bgw_notify_pid == MyProcPid)\n worker->bgw_notify_pgprocno = MyProcNumber;\n\nI think we can forbid setting pgw_notify_pid to anything else than 0 or \nMyProcPid.\n\nA SetLatchRobust would be nice. Looking at SetLatch(), I don't think it \ncan do any damage if you called it on a pointer to garbage, except if \nthe pointer itself is bogus, then just dereferencing it an cause a \nsegfault. So it would be nice to have a version specifically designed \nwith that in mind. For example, it could assume that the Latch's pid is \nnever legally equal to MyProcPid, because postmaster cannot own any latches.\n\nAnother approach would be to move the responsibility of background \nworker state notifications out of postmaster completely. When a new \nbackground worker is launched, the worker process itself could send the \nnotification that it has started. And similarly, when a worker exits, it \ncould send the notification just before exiting. There's a little race \ncondition with exiting: if a process is waiting for the bgworker to \nexit, and launches a new worker immediately when the old one exits, \nthere will be a brief period when the old and new process are alive at \nthe same time. The old worker wouldn't be doing anything interesting \nanymore since it's exiting, but it still counts towards \nmax_worker_processes, so launching the new process might fail because of \nhitting the limit. Maybe we should just bump up max_worker_processes. Or \npostmaster could check PMChildFlags and not count processes that have \nalready deregistered from PMChildFlags towards the limit.\n\n> -volatile uint32 InterruptHoldoffCount = 0;\n> -volatile uint32 QueryCancelHoldoffCount = 0;\n> -volatile uint32 CritSectionCount = 0;\n> +uint32 InterruptHoldoffCount = 0;\n> +uint32 QueryCancelHoldoffCount = 0;\n> +uint32 CritSectionCount = 0;\n\nI wondered if these are used in PG_TRY-CATCH blocks in a way that would \nstill require volatile. I couldn't find any such usage by some quick \ngrepping, so I think we're good, but I thought I'd mention it.\n\n> +/*\n> + * The set of \"standard\" interrupts that CHECK_FOR_INTERRUPTS() and\n> + * ProcessInterrupts() handle. These perform work that is safe to run whenever\n> + * interrupts are not \"held\". Other kinds of interrupts are only handled at\n> + * more restricted times.\n> + */\n> +#define INTERRUPT_STANDARD_MASK\t\t\t\t\t\t\t \\\n\nSome interrupts are missing from this mask:\n\n- INTERRUPT_PARALLEL_APPLY_MESSAGE\n- INTERRUPT_IDLE_STATS_UPDATE_TIMEOUT\n- INTERRUPT_SINVAL_CATCHUP\n- INTERRUPT_NOTIFY\n\nIs that on purpose?\n\n> -/*\n> - * Because backends sitting idle will not be reading sinval events, we\n> - * need a way to give an idle backend a swift kick in the rear and make\n> - * it catch up before the sinval queue overflows and forces it to go\n> - * through a cache reset exercise. This is done by sending\n> - * PROCSIG_CATCHUP_INTERRUPT to any backend that gets too far behind.\n> - *\n> - * The signal handler will set an interrupt pending flag and will set the\n> - * processes latch. Whenever starting to read from the client, or when\n> - * interrupted while doing so, ProcessClientReadInterrupt() will call\n> - * ProcessCatchupEvent().\n> - */\n> -volatile sig_atomic_t catchupInterruptPending = false;\n\nWould be nice to move that comment somewhere else rather than remove it \ncompletely.\n\n> --- a/src/backend/storage/lmgr/proc.c\n> +++ b/src/backend/storage/lmgr/proc.c\n> @@ -444,6 +444,10 @@ InitProcess(void)\n> \tOwnLatch(&MyProc->procLatch);\n> \tSwitchToSharedLatch();\n> \n> +\t/*We're now ready to accept interrupts from other processes. */\n> +\tpg_atomic_init_u32(&MyProc->pending_interrupts, 0);\n> +\tSwitchToSharedInterrupts();\n> +\n> \t/* now that we have a proc, report wait events to shared memory */\n> \tpgstat_set_wait_event_storage(&MyProc->wait_event_info);\n> \n> @@ -611,6 +615,9 @@ InitAuxiliaryProcess(void)\n> \tOwnLatch(&MyProc->procLatch);\n> \tSwitchToSharedLatch();\n> \n> +\t/* We're now ready to accept interrupts from other processes. */\n> +\tSwitchToSharedInterrupts();\n> +\n> \t/* now that we have a proc, report wait events to shared memory */\n> \tpgstat_set_wait_event_storage(&MyProc->wait_event_info);\n> \n\nIs there a reason for the different initialization between a regular \nbackend and aux process?\n\n> +/*\n> + * Switch to shared memory interrupts. Other backends can send interrupts\n> + * to this one if they know its ProcNumber.\n> + */\n> +void\n> +SwitchToSharedInterrupts(void)\n> +{\n> +\tpg_atomic_fetch_or_u32(&MyProc->pending_interrupts, pg_atomic_read_u32(MyPendingInterrupts));\n> +\tMyPendingInterrupts = &MyProc->pending_interrupts;\n> +}\n\nHmm, I think there's a race condition here (and similarly in \nSwitchToLocalInterrupts), if the signal handler runs between the \npg_atomic_fetch_or_u32, and changing MyPendingInterrupts. Maybe \nsomething like this instead:\n\nMyPendingInterrupts = &MyProc->pending_interrupts;\npg_memory_barrier();\npg_atomic_fetch_or_u32(&MyProc->pending_interrupts, \npg_atomic_read_u32(LocalPendingInterrupts));\n\nAnd perhaps this should also clear LocalPendingInterrupts, just to be tidy.\n\n> @@ -138,7 +139,8 @@\n> typedef struct ProcState\n> {\n> \t/* procPid is zero in an inactive ProcState array entry. */\n> -\tpid_t\t\tprocPid;\t\t/* PID of backend, for signaling */\n> +\tpid_t\t\tprocPid;\t\t/* pid of backend */\n> +\tProcNumber\tpgprocno;\t\t/* for sending interrupts */\n> \t/* nextMsgNum is meaningless if procPid == 0 or resetState is true. */\n> \tint\t\t\tnextMsgNum;\t\t/* next message number to read */\n> \tbool\t\tresetState;\t\t/* backend needs to reset its state */\n\nWe can easily remove procPid altogether now that we have pgprocno here. \nSimilarly with the pid/pgprocno in ReplicationSlot and WalSndState.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)\n\n\n\n","msg_date":"Mon, 8 Jul 2024 12:38:22 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Mon, Jul 8, 2024 at 5:38 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n> Another approach would be to move the responsibility of background\n> worker state notifications out of postmaster completely. When a new\n> background worker is launched, the worker process itself could send the\n> notification that it has started. And similarly, when a worker exits, it\n> could send the notification just before exiting. There's a little race\n> condition with exiting: if a process is waiting for the bgworker to\n> exit, and launches a new worker immediately when the old one exits,\n> there will be a brief period when the old and new process are alive at\n> the same time. The old worker wouldn't be doing anything interesting\n> anymore since it's exiting, but it still counts towards\n> max_worker_processes, so launching the new process might fail because of\n> hitting the limit. Maybe we should just bump up max_worker_processes. Or\n> postmaster could check PMChildFlags and not count processes that have\n> already deregistered from PMChildFlags towards the limit.\n\nI can testify that the current system is the result of a lot of trial\nand error. I'm not saying it can't be made better, but my initial\nattempts at getting this to work (back in the 9.4 era) resembled what\nyou proposed here, were consequently a lot simpler than what we have\nnow, and also did not work. Race conditions like you mention here were\npart of that. Another consideration is that fork() can fail, and in\nthat case, the process that tried to register the new background\nworker needs to find out that the background worker won't ever be\nstarting. Yet another problem is that, even if fork() succeeds, the\nnew process might fail before it executes any of our code e.g. because\nit seg faults very early, a case that actually happened to me -\ninadvertently - while I was testing these facilities. I ended up\ndeciding that we can't rely on the new process to do anything until\nit's given us some signal that it is alive and able to carry out its\nduties. If it dies before telling us that, or never starts in the\nfirst place, we have to have some other way of finding that out, and\nit's difficult to see how that can happen without postmaster\ninvolvement.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 8 Jul 2024 16:18:01 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Mon, Jul 8, 2024 at 9:38 PM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n> The patch actually does both: it still does kill(SIGUSR1) and also sets\n> the latch.\n\nYeah, I had some ideas about supporting old extension code that really\nwanted a SIGUSR1, but on reflection, the only reason anyone ever wants\nthat is so that sigusr1_handler can SetLatch(), which pairs with\nWaitLatch() in WaitForBackgroundWorker*(). Let's go all the way and\nassume that.\n\n> I think it would be nice if RegisterDynamicBackgroundWorker() had a\n> \"bool notify_me\" argument, instead of requiring the caller to set\n> \"bgw_notify_pid = MyProcPid\" before the call. That's a\n> backwards-compatibility break, but maybe we should bite the bullet and\n> do it. Or we could do this in RegisterDynamicBackgroundWorker():\n>\n> if (worker->bgw_notify_pid == MyProcPid)\n> worker->bgw_notify_pgprocno = MyProcNumber;\n>\n> I think we can forbid setting pgw_notify_pid to anything else than 0 or\n> MyProcPid.\n\nAnother idea: we could keep the bgw_notify_pid field around for a\nwhile, documented as unused and due to be removed in future. We could\nautomatically capture the caller's proc number. So you get latch\nwakeups by default, which I expect many people want, and most people\ncould cope with even if they don't want them. If you really really\ndon't want them, you could set a new flag BGW_NO_NOTIFY.\n\nI have now done this part of the change in a new first patch. This\nparticular use of kill(SIGUSR1) is separate from the ProcSignal\nremoval, it's just that it relies on ProcSignal's handler's default\naction of calling SetLatch(). It's needed so the ProcSignal-ectomy\ncan fully delete sigusr1_handler(), but it's not directly the same\nthing, so it seemed good to split the patch.\n\n> A SetLatchRobust would be nice. Looking at SetLatch(), I don't think it\n> can do any damage if you called it on a pointer to garbage, except if\n> the pointer itself is bogus, then just dereferencing it an cause a\n> segfault. So it would be nice to have a version specifically designed\n> with that in mind. For example, it could assume that the Latch's pid is\n> never legally equal to MyProcPid, because postmaster cannot own any latches.\n\nYeah I'm starting to think that all we need to do here is range-check\nthe proc number. Here's a version that adds:\nProcSetLatch(proc_number). Another idea would be for SetLatch(latch)\nto sanitise the address of a latch, ie its offset and range.\n\nWhat the user really wants to be able to do with this bgworker API, I\nthink, is wait for a given a handle, which could find a condition\nvariable + generation in the slot, so that we don't have to register\nany proc numbers anywhere until we're actually waiting. But *clearly*\nthe postmaster can't use the condition variable API without risking\nfollowing corrupted pointers in shared memory. Whereas AFAICT\nProcSetLatch() from the patched postmaster can't really be corrupted\nin any new way that it couldn't already be corrupted in master (where\nit runs in the target process), if we're just a bit paranoid about how\nwe find our way to the latch.\n\nReceiving latch wakeups in the postmaster might be another question,\nbut I don't think we need to confront that question just yet.\n\n> > -volatile uint32 InterruptHoldoffCount = 0;\n> > -volatile uint32 QueryCancelHoldoffCount = 0;\n> > -volatile uint32 CritSectionCount = 0;\n> > +uint32 InterruptHoldoffCount = 0;\n> > +uint32 QueryCancelHoldoffCount = 0;\n> > +uint32 CritSectionCount = 0;\n>\n> I wondered if these are used in PG_TRY-CATCH blocks in a way that would\n> still require volatile. I couldn't find any such usage by some quick\n> grepping, so I think we're good, but I thought I'd mention it.\n\nHmm. Still thinking about this.\n\n> > +/*\n> > + * The set of \"standard\" interrupts that CHECK_FOR_INTERRUPTS() and\n> > + * ProcessInterrupts() handle. These perform work that is safe to run whenever\n> > + * interrupts are not \"held\". Other kinds of interrupts are only handled at\n> > + * more restricted times.\n> > + */\n> > +#define INTERRUPT_STANDARD_MASK \\\n>\n> Some interrupts are missing from this mask:\n>\n> - INTERRUPT_PARALLEL_APPLY_MESSAGE\n\nOops, that one ^ is a rebasing mistake. I wrote the ancestor of this\npatch in 2021, and that new procsignal arrived in 2023, and I put the\ncode in to handle it, but I forgot to add it to the mask, which gives\nme an idea (see below)...\n\n> - INTERRUPT_IDLE_STATS_UPDATE_TIMEOUT\n> - INTERRUPT_SINVAL_CATCHUP\n> - INTERRUPT_NOTIFY\n>\n> Is that on purpose?\n\nINTERRUPT_SINVAL_CATCHUP and INTERRUPT_NOTIFY are indeed handled\ndifferently on purpose. In master, they don't set InterruptPending,\nand they are not handled by regular CHECK_FOR_INTERRUPTS() sites, but\nin the patch they still need a bit in pending_interrupts, and that is\nwhat that mask hides from CHECK_FOR_INTERRUPTS(). They are checked\nexplicitly in ProcessClientReadInterrupt(). I think the idea is that\nwe can't handle sinval at random places because that might create\ndangling pointers to cached objects where we don't expect them, and we\ncan't emit NOTIFY-related protocol messages at random times either.\n\nThere is something a little funky about _IDLE_STATS_UPDATE_TIMEOUT,\nthough. It has a different scheme for running only when idle, where\nif it opts not to do anything, it doesn't consume the interrupt (a\nlater CFI() will, but the latch is not set so we might sleep). I was\nconfused by that. I think I have changed to be more faithful to\nmaster's behaviour now.\n\nHmm, a better terminology for the interupts that CFI handles would be\ns/standard/regular/, so I have changed that.\n\nNew idea: it would be less error-prone if we instead had a mask of\nthese special cases, of which there are now only two. Tried that way!\n\n> > -/*\n> > - * Because backends sitting idle will not be reading sinval events, we\n> > - * need a way to give an idle backend a swift kick in the rear and make\n> > - * it catch up before the sinval queue overflows and forces it to go\n> > - * through a cache reset exercise. This is done by sending\n> > - * PROCSIG_CATCHUP_INTERRUPT to any backend that gets too far behind.\n> > - *\n> > - * The signal handler will set an interrupt pending flag and will set the\n> > - * processes latch. Whenever starting to read from the client, or when\n> > - * interrupted while doing so, ProcessClientReadInterrupt() will call\n> > - * ProcessCatchupEvent().\n> > - */\n> > -volatile sig_atomic_t catchupInterruptPending = false;\n>\n> Would be nice to move that comment somewhere else rather than remove it\n> completely.\n\nOK, I moved it to the top of ProcessCatchupInterrupt().\n\n> > --- a/src/backend/storage/lmgr/proc.c\n> > +++ b/src/backend/storage/lmgr/proc.c\n> > @@ -444,6 +444,10 @@ InitProcess(void)\n> > OwnLatch(&MyProc->procLatch);\n> > SwitchToSharedLatch();\n> >\n> > + /*We're now ready to accept interrupts from other processes. */\n> > + pg_atomic_init_u32(&MyProc->pending_interrupts, 0);\n> > + SwitchToSharedInterrupts();\n> > +\n> > /* now that we have a proc, report wait events to shared memory */\n> > pgstat_set_wait_event_storage(&MyProc->wait_event_info);\n> >\n> > @@ -611,6 +615,9 @@ InitAuxiliaryProcess(void)\n> > OwnLatch(&MyProc->procLatch);\n> > SwitchToSharedLatch();\n> >\n> > + /* We're now ready to accept interrupts from other processes. */\n> > + SwitchToSharedInterrupts();\n> > +\n> > /* now that we have a proc, report wait events to shared memory */\n> > pgstat_set_wait_event_storage(&MyProc->wait_event_info);\n> >\n>\n> Is there a reason for the different initialization between a regular\n> backend and aux process?\n\nNo. But I thought about something else to fix here. Really we don't\nwant to switch to shared interrupts until we are ready for CFI() to do\nstuff. I think that should probably be at the places where master\nunblocks signals. Otherwise, for example, if someone sends you an\ninterrupt while you're starting up, something as innocent as\nelog(DEBUG, ...), which reaches CFI(), might try to do things for\nwhich the infrastructure is not yet fully set up, for example\nINTERRUPT_BARRIER.\n\nNot done yet, but wanted to share this new version.\n\n> > +/*\n> > + * Switch to shared memory interrupts. Other backends can send interrupts\n> > + * to this one if they know its ProcNumber.\n> > + */\n> > +void\n> > +SwitchToSharedInterrupts(void)\n> > +{\n> > + pg_atomic_fetch_or_u32(&MyProc->pending_interrupts, pg_atomic_read_u32(MyPendingInterrupts));\n> > + MyPendingInterrupts = &MyProc->pending_interrupts;\n> > +}\n>\n> Hmm, I think there's a race condition here (and similarly in\n> SwitchToLocalInterrupts), if the signal handler runs between the\n> pg_atomic_fetch_or_u32, and changing MyPendingInterrupts. Maybe\n> something like this instead:\n>\n> MyPendingInterrupts = &MyProc->pending_interrupts;\n> pg_memory_barrier();\n> pg_atomic_fetch_or_u32(&MyProc->pending_interrupts,\n> pg_atomic_read_u32(LocalPendingInterrupts));\n\nYeah, right, done.\n\n> And perhaps this should also clear LocalPendingInterrupts, just to be tidy.\n\nI used atomic_exchange() to read and clear the bits in one go.\n\n> > @@ -138,7 +139,8 @@\n> > typedef struct ProcState\n> > {\n> > /* procPid is zero in an inactive ProcState array entry. */\n> > - pid_t procPid; /* PID of backend, for signaling */\n> > + pid_t procPid; /* pid of backend */\n> > + ProcNumber pgprocno; /* for sending interrupts */\n> > /* nextMsgNum is meaningless if procPid == 0 or resetState is true. */\n> > int nextMsgNum; /* next message number to read */\n> > bool resetState; /* backend needs to reset its state */\n>\n> We can easily remove procPid altogether now that we have pgprocno here.\n\nSince other things access those values, I propose to remove them in\nseparate patches.\n\n> Similarly with the pid/pgprocno in ReplicationSlot and WalSndState.\n\nSame. Those pids show up in user interfaces, so I think they should\nbe handled in separate patches.\n\nNote to self: I need to change some pgprocno to proc_number...\n\nThe next problems to remove are, I think, the various SIGUSR2, SIGINT,\nSIGTERM signals sent by the postmaster. These should clearly become\nSendInterrupt() or ProcSetLatch(). The problem here is that the\npostmaster doesn't have the proc numbers yet. One idea is to teach\nthe postmaster to assign them! Not explored yet.\n\nThis version is passing on Windows. I'll create a CF entry. Still\nwork in progress!","msg_date":"Wed, 10 Jul 2024 18:48:48 +1200","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 10/07/2024 09:48, Thomas Munro wrote:\n> On Mon, Jul 8, 2024 at 9:38 PM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n>> The patch actually does both: it still does kill(SIGUSR1) and also sets\n>> the latch.\n> \n> Yeah, I had some ideas about supporting old extension code that really\n> wanted a SIGUSR1, but on reflection, the only reason anyone ever wants\n> that is so that sigusr1_handler can SetLatch(), which pairs with\n> WaitLatch() in WaitForBackgroundWorker*(). Let's go all the way and\n> assume that.\n\n+1\n\n>> I think it would be nice if RegisterDynamicBackgroundWorker() had a\n>> \"bool notify_me\" argument, instead of requiring the caller to set\n>> \"bgw_notify_pid = MyProcPid\" before the call. That's a\n>> backwards-compatibility break, but maybe we should bite the bullet and\n>> do it. Or we could do this in RegisterDynamicBackgroundWorker():\n>>\n>> if (worker->bgw_notify_pid == MyProcPid)\n>> worker->bgw_notify_pgprocno = MyProcNumber;\n>>\n>> I think we can forbid setting pgw_notify_pid to anything else than 0 or\n>> MyProcPid.\n> \n> Another idea: we could keep the bgw_notify_pid field around for a\n> while, documented as unused and due to be removed in future. We could\n> automatically capture the caller's proc number. So you get latch\n> wakeups by default, which I expect many people want, and most people\n> could cope with even if they don't want them. If you really really\n> don't want them, you could set a new flag BGW_NO_NOTIFY.\n\nOk. I was going to say that it feels excessive to change the default \nlike that. However, searching for RegisterDynamicBackgroundWorker() in \ngithub, I can't actually find any callers that don't set pg_notify_pid. \nSo yeah, make sense.\n\n> I have now done this part of the change in a new first patch. This\n> particular use of kill(SIGUSR1) is separate from the ProcSignal\n> removal, it's just that it relies on ProcSignal's handler's default\n> action of calling SetLatch(). It's needed so the ProcSignal-ectomy\n> can fully delete sigusr1_handler(), but it's not directly the same\n> thing, so it seemed good to split the patch.\n\nPostmasterMarkPIDForWorkerNotify() is now unused. Which means that \nbgworker_notify is never set, and BackgroundWorkerStopNotifications() is \nnever called either.\n\n>> A SetLatchRobust would be nice. Looking at SetLatch(), I don't think it\n>> can do any damage if you called it on a pointer to garbage, except if\n>> the pointer itself is bogus, then just dereferencing it an cause a\n>> segfault. So it would be nice to have a version specifically designed\n>> with that in mind. For example, it could assume that the Latch's pid is\n>> never legally equal to MyProcPid, because postmaster cannot own any latches.\n> \n> Yeah I'm starting to think that all we need to do here is range-check\n> the proc number. Here's a version that adds:\n> ProcSetLatch(proc_number). Another idea would be for SetLatch(latch)\n> to sanitise the address of a latch, ie its offset and range.\n\nHmm, I don't think postmaster should trust ProcGlobal->allProcCount either.\n\n> The next problems to remove are, I think, the various SIGUSR2, SIGINT,\n> SIGTERM signals sent by the postmaster. These should clearly become\n> SendInterrupt() or ProcSetLatch().\n\n+1\n\n> The problem here is that the\n> postmaster doesn't have the proc numbers yet. One idea is to teach\n> the postmaster to assign them! Not explored yet.\n\nI've been thinking that we should:\n\na) assign every child process a PGPROC entry, and make postmaster \nresponsible for assigning them like you suggest. We'll need more PGPROC \nentries, because currently a process doesn't reserve one until \nauthentication has happened. Or we change that behavior.\n\nor\n\nb) Use the pmsignal.c slot numbers for this, instead of ProcNumbers. \nPostmaster already assigns those.\n\nI'm kind of leaning towards b) for now, because it feels like a much \nsmaller patch. In the long run, it would be nice if every child process \nhad a ProcNumber, though. It was a nice simplification in v17 that we \ndon't have separate BackendId and ProcNumber anymore; similarly it would \nbe nice to not have separate PMChildSlot and ProcNumber concepts.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)\n\n\n\n","msg_date":"Wed, 24 Jul 2024 15:57:58 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Wed, Jul 24, 2024 at 8:58 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n> a) assign every child process a PGPROC entry, and make postmaster\n> responsible for assigning them like you suggest. We'll need more PGPROC\n> entries, because currently a process doesn't reserve one until\n> authentication has happened. Or we change that behavior.\n\nI wonder how this works right now. Is there something that limits the\nnumber of authentication requests that can be in flight concurrently,\nor is it completely uncapped (except by machine resources)?\n\nMy first thought when I read this was that it would be bad to have to\nput a limit on something that's currently unlimited. But then I\nstarted thinking that, even if it is currently unlimited, that might\nbe a bug rather than a feature. If you have hundreds of pending\nauthentication requests, that just means you're using a lot of machine\nresources on something that doesn't really help anybody. A machine\nwith hundreds of authentication-pending connections is possibly\ngetting DDOS'd and probably getting buried. You'd be better off\nfocusing the machine's limited resources on the already-established\nconnections and a more limited number of new connection attempts. If\nyou accept so many connection attempts that you don't actually have\nenough memory/CPU/kernel scheduling firepower to complete the\nauthentication process with any of them, it does nobody any good.\n\nI'm not sure what's best to do here; just thinking out loud.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 29 Jul 2024 12:56:52 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 29/07/2024 19:56, Robert Haas wrote:\n> On Wed, Jul 24, 2024 at 8:58 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n>> a) assign every child process a PGPROC entry, and make postmaster\n>> responsible for assigning them like you suggest. We'll need more PGPROC\n>> entries, because currently a process doesn't reserve one until\n>> authentication has happened. Or we change that behavior.\n> \n> I wonder how this works right now. Is there something that limits the\n> number of authentication requests that can be in flight concurrently,\n> or is it completely uncapped (except by machine resources)?\n\n> My first thought when I read this was that it would be bad to have to\n> put a limit on something that's currently unlimited. But then I\n> started thinking that, even if it is currently unlimited, that might\n> be a bug rather than a feature. If you have hundreds of pending\n> authentication requests, that just means you're using a lot of machine\n> resources on something that doesn't really help anybody. A machine\n> with hundreds of authentication-pending connections is possibly\n> getting DDOS'd and probably getting buried. You'd be better off\n> focusing the machine's limited resources on the already-established\n> connections and a more limited number of new connection attempts. If\n> you accept so many connection attempts that you don't actually have\n> enough memory/CPU/kernel scheduling firepower to complete the\n> authentication process with any of them, it does nobody any good.\n> \n> I'm not sure what's best to do here; just thinking out loud.\n\nYes, there's a limit, roughly 2x max_connections. see \nMaxLivePostmasterChildren().\n\nThere's another issue with that that I was about to post in another \nthread, but here goes: the MaxLivePostmasterChildren() limit is shared \nby all regular backends, bgworkers and autovacuum workers. If you open a \nlot of TCP connections to postmaster and don't send anything to the \nserver, you exhaust those slots, and the server won't be able to start \nany autovacuum workers or background workers either. That's not great. I \nstarted to work on approach b), with separate pools of slots for \ndifferent kinds of child processes, which fixes that. Stay tuned for a \npatch.\n\nIn addition to that, you can have an unlimited number of \"dead-end\" \nbackends, which are doomed to just respond with \"sorry, too many \nclients\" error. The only limit on those is the amount of resources \nneeded for all the processes and a little memory to track them.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)\n\n\n\n","msg_date":"Mon, 29 Jul 2024 20:18:22 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> I wonder how this works right now. Is there something that limits the\n> number of authentication requests that can be in flight concurrently,\n> or is it completely uncapped (except by machine resources)?\n\nThe former. IIRC, the postmaster won't spawn more than 2X max_connections\nsubprocesses (don't recall the exact limit, but it's around there).\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 29 Jul 2024 13:24:21 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Mon, Jul 29, 2024 at 1:24 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Robert Haas <robertmhaas@gmail.com> writes:\n> > I wonder how this works right now. Is there something that limits the\n> > number of authentication requests that can be in flight concurrently,\n> > or is it completely uncapped (except by machine resources)?\n>\n> The former. IIRC, the postmaster won't spawn more than 2X max_connections\n> subprocesses (don't recall the exact limit, but it's around there).\n\nHmm. Not to sidetrack this thread too much, but multiplying by two\ndoesn't really sound like the right idea to me. The basic idea\narticulated in the comment for canAcceptConnections() makes sense:\nsome backends might fail authentication, or might be about to exit, so\nit makes sense to allow for some slop. But 2X is a lot of slop even on\na machine with the default max_connections=100, and people with\nconnection management problems are likely to be running with\nmax_connections=500 or max_connections=900 or even (insanely)\nmax_connections=2000. Continuing with a connection attempt because we\nthink that hundreds or thousands of connections that are ahead of us\nin the queue might clear out of the way before we need a PGPROC is not\na good bet.\n\nI wonder if we ought to restrict this to a small, flat value, like say\n50, or by a new GUC that defaults to such a value if a constant seems\nproblematic. Maybe it doesn't really matter. I'm not sure how much\nwork we'd save by booting out the doomed connection attempt earlier.\n\nThe unlimited number of dead-end backends doesn't sound too great\neither. I don't have another idea, but presumably resisting DDOS\nattacks and/or preserving resources for things that still have a\nchance of working ought to take priority over printing a nicer error\nmessage from a connection that's doomed to fail anyway.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 29 Jul 2024 14:05:18 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 10/07/2024 09:48, Thomas Munro wrote:\n> The next problems to remove are, I think, the various SIGUSR2, SIGINT,\n> SIGTERM signals sent by the postmaster. These should clearly become\n> SendInterrupt() or ProcSetLatch(). The problem here is that the\n> postmaster doesn't have the proc numbers yet. One idea is to teach\n> the postmaster to assign them! Not explored yet.\n\nWith my latest patches on the \"Refactoring postmaster's code to cleanup \nafter child exit\" thread [1], every postmaster child process is assigned \na slot in the pmsignal.c array, including all the aux processes. If we \nmoved 'pending_interrupts' and the process Latch to the pmsignal.c \narray, then you could send an interrupt also to a process that doesn't \nhave a PGPROC entry. That includes dead-end backends, backends that are \nstill in authentication, and the syslogger.\n\nThat would also make it so that the postmaster would never need to poke \ninto the procarray. pmsignal.c is already designated as the limited \npiece of shared memory that is accessed by the postmaster \n(BackgroundWorkerSlots is the other exception), so it would be kind of \nnice if all the information that the postmaster needs to send an \ninterrupt was there. That would mean that where you currently use a \nProcNumber to identify a process, you'd use an index into the \nPMSignalState array instead.\n\nI don't insist on changing that right now, I think this patch is OK as \nit is, but that might be a good next step later.\n\n[1] \nhttps://www.postgresql.org/message-id/8f2118b9-79e3-4af7-b2c9-bd5818193ca4%40iki.fi\n\nI'm also wondering about the relationship between interrupts and \nlatches. Currently, SendInterrupt sets a latch to wake up the target \nprocess. I wonder if it should be the other way 'round? Move all the \nwakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in \nSetLatch, call SendInterrupt to wake up the target process? Somehow that \nfeels more natural to me, I think.\n\n> This version is passing on Windows. I'll create a CF entry. Still\n> work in progress!\n\nSome comments on the patch details:\n\n> \t\tereport(WARNING,\n> \t\t\t\t(errmsg(\"NOTIFY queue is %.0f%% full\", fillDegree * 100),\n> -\t\t\t\t (minPid != InvalidPid ?\n> -\t\t\t\t errdetail(\"The server process with PID %d is among those with \nthe oldest transactions.\", minPid)\n> +\t\t\t\t (minPgprocno != INVALID_PROC_NUMBER ?\n> +\t\t\t\t errdetail(\"The server process with pgprocno %d is among those \nwith the oldest transactions.\", minPgprocno)\n> \t\t\t\t : 0),\n> -\t\t\t\t (minPid != InvalidPid ?\n> +\t\t\t\t (minPgprocno != INVALID_PROC_NUMBER ?\n> \t\t\t\t errhint(\"The NOTIFY queue cannot be emptied until that process \nends its current transaction.\")\n> \t\t\t\t : 0)));\n\nThis makes the message less useful to the user, as the ProcNumber isn't \nexposed to users. With the PID, you can do \"pg_terminate_backend(pid)\"\n\n> diff --git a/src/backend/optimizer/util/pathnode.c \nb/src/backend/optimizer/util/pathnode.c\n> index c42742d2c7b..bfb89049020 100644\n> --- a/src/backend/optimizer/util/pathnode.c\n> +++ b/src/backend/optimizer/util/pathnode.c\n> @@ -18,6 +18,7 @@\n>\n> #include \"foreign/fdwapi.h\"\n> #include \"miscadmin.h\"\n> +#include \"postmaster/interrupt.h\"\n> #include \"nodes/extensible.h\"\n> #include \"optimizer/appendinfo.h\"\n> #include \"optimizer/clauses.h\"\n\nmisordered\n\n> +\t * duplicated interrupts later if we switch backx.\n\ntypo: backx -> back\n\n> -\tif (IdleInTransactionSessionTimeoutPending)\n> +\tif (ConsumeInterrupt(INTERRUPT_IDLE_TRANSACTION_TIMEOUT))\n> \t{\n> \t\t/*\n> \t\t * If the GUC has been reset to zero, ignore the signal. This is\n> @@ -3412,7 +3361,6 @@ ProcessInterrupts(void)\n> \t\t * interrupt. We need to unset the flag before the injection point,\n> \t\t * otherwise we could loop in interrupts checking.\n> \t\t */\n> -\t\tIdleInTransactionSessionTimeoutPending = false;\n> \t\tif (IdleInTransactionSessionTimeout > 0)\n> \t\t{\n> \t\t\tINJECTION_POINT(\"idle-in-transaction-session-timeout\");\n\nThe \"We need to unset the flag..\" comment is a bit out of place now, \nsince the flag was already cleared by ConsumeInterrupt(). Same in the \nINTERRUPT_TRANSACTION_TIMEOUT and INTERRUPT_IDLE_SESSION_TIMEOUT \nhandling after this.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)\n\n\n\n","msg_date":"Wed, 7 Aug 2024 17:59:23 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 07/08/2024 17:59, Heikki Linnakangas wrote:\n> I'm also wondering about the relationship between interrupts and \n> latches. Currently, SendInterrupt sets a latch to wake up the target \n> process. I wonder if it should be the other way 'round? Move all the \n> wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in \n> SetLatch, call SendInterrupt to wake up the target process? Somehow that \n> feels more natural to me, I think.\n\nI explored that a little, see attached patch set. It's going towards the \nsame end state as your patches, I think, but it starts from different \nangle. In a nutshell:\n\nRemove Latch as an abstraction, and replace all use of Latches with \nInterrupts. When I originally created the Latch abstraction, I imagined \nthat we would have different latches for different purposes, but in \nreality, almost all code just used the general-purpose \"process latch\". \nthis patch accepts that reality and replaces the Latch struct directly \nwith the interrupt mask in PGPROC.\n\nThis initially defines only two interrupts. INTERRUPT_GENERAL_WAKEUP is \nthe main one, sending that interrupt to a process replaces setting the \nprocess's generic process latch in PGPROC:\n\n* SetLatch(MyLatch) -> RaiseInterrupt(INTERRUPT_GENERAL_WAKEUP)\n\n* SetLatch(&ProcGlobal->allProcs[procno].procLatch) -> \nSendInterrupt(procno, INTERRUPT_GENERAL_WAKEUP\n\n* ResetLatch(MyLatch) -> ClearInterrupt(INTERRUPT_GENERAL_WAKEUP)\n\n* WaitLatch(MyLatch) -> WaitInterrupt(1 << INTERRUPT_GENERAL_WAKEUP)\n\nThere was only one extra Latch in addition the process's generic \nprocLatch, the recoveryWakeupLatch. It's replaced by the second \ninterrupt bit, INTERRUPT_RECOVERY_WAKEUP.\n\nThis is complementary or preliminary work to your patch set. All the \nchanges to replace ProcSignals with different interrupt bits could go on \ntop of this.\n\nThis patch set is work in progress, I'd love to hear your thoughts on \nthis before I spent more time on this. (Haven't tested on Windows for \nexample).\n\nPatches 0001 - 0006 are just little cleanups and minor refactorings that \nI think make sense even without the rest of the work, though.\n\n0007 is the main patch.\n\nPatch 0010 addresses the problem discussed at \nhttps://www.postgresql.org/message-id/CALDaNm01_KEgHM1tKtgXkCGLJ5209SMSmGw3UmhZbOz365_%3DeA%40mail.gmail.com. \nOther solutions are discussed on that thread, but while working on \nthese, I realized that with these new interrupts, it's pretty \nstraightforward to fix by introducing one more interrupt reason.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)","msg_date":"Sat, 24 Aug 2024 20:17:47 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Sun, Aug 25, 2024 at 5:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n> On 07/08/2024 17:59, Heikki Linnakangas wrote:\n> > I'm also wondering about the relationship between interrupts and\n> > latches. Currently, SendInterrupt sets a latch to wake up the target\n> > process. I wonder if it should be the other way 'round? Move all the\n> > wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in\n> > SetLatch, call SendInterrupt to wake up the target process? Somehow that\n> > feels more natural to me, I think.\n>\n> I explored that a little, see attached patch set. It's going towards the\n> same end state as your patches, I think, but it starts from different\n> angle. In a nutshell:\n>\n> Remove Latch as an abstraction, and replace all use of Latches with\n> Interrupts. When I originally created the Latch abstraction, I imagined\n> that we would have different latches for different purposes, but in\n> reality, almost all code just used the general-purpose \"process latch\".\n> this patch accepts that reality and replaces the Latch struct directly\n> with the interrupt mask in PGPROC.\n\nSome very initial reactions:\n\n* I like it!\n\n* This direction seems to fit quite nicely with future ideas about\nasynchronous network I/O. That may sound unrelated, but imagine that\na future version of WaitEventSet is built on Linux io_uring (or\nWindows iorings, or Windows IOCP, or kqueue), and waits for the kernel\nto tell you that network data has been transferred directly into a\nuser space buffer. You could wait for the interrupt word to change at\nthe same time by treating it as a futex[1]. Then all that other stuff\n-- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\nleft is one single word in memory. (That it is possible to do that is\nnot really a coincidence, as our own Mr Freund asked Mr Axboe to add\nit[2]. The existing latch implementation techniques could be used as\nfallbacks, but when looked at from the right angle, once you squish\nall the wakeup reasons into a single word, it's all just an\nimplementation of a multiplexable futex with extra steps.)\n\n* Speaking of other problems in other threads that might be solved by\nthis redesign, I think I see the outline of some solutions to the\nproblem of different classes of wakeup which you can handle at\ndifferent times, using masks. There is a tension in a few places\nwhere we want to handle some kind of interrupts but not others in\nlocalised wait points, which we sort of try to address by holding\ninterrupts or holding cancel interrupts, but it's not satisfying and\nthere are some places where it doesn't work well. Needs a lot more\nthought, but a basic step would be: after old_interrupt_vector =\npg_atomic_fetch_or_u32(interrupt_vector, new_bits), if\n(old_interrupt_vector & new_bits) == new_bits, then you didn't\nactually change any bits, so you probably don't really need to wake\nthe other backend. If someone is currently unable to handle that type\nof interrupt (has ignored, ie not cleared, those bits) or is already\nin the process of handling it (is currently being rescheduled but\nhasn't cleared those bits yet), then you don't bother to wake it up.\nConcretely, it could mean that we avoid some of the useless wakeup\nstorm problems we see in vacuum delays or while executing a query and\nnot in a good place to handle sinval wakeups, etc. These are just\nsome raw thoughts, I am not sure about the bigger picture of that\ntopic yet.\n\n* Archeological note on terminology: the reason almost every relation\ndatabase and all the literature uses the term \"latch\" for something\nlike our LWLocks seems to be that latches were/are one of the kinds of\nsystem-provided mutex on IBM System/370 and modern descendents ie\nz/OS. Oracle and other systems that started as knock-offs of the IBM\nSystem R (the original SQL system, of which DB2 is the modern heir)\ncontinued that terminology, even though they ran on VMS or Unix or\nwhatever. I would not be sad if we removed our unusual use of the\nterm latch.\n\n[1] https://man7.org/linux/man-pages/man3/io_uring_prep_futex_wait.3.html\n[2] https://lore.kernel.org/lkml/20230720221858.135240-1-axboe@kernel.dk/\n\n\n","msg_date":"Mon, 26 Aug 2024 11:05:46 +1200","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On 26/08/2024 02:05, Thomas Munro wrote:\n> On Sun, Aug 25, 2024 at 5:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n>> On 07/08/2024 17:59, Heikki Linnakangas wrote:\n>>> I'm also wondering about the relationship between interrupts and\n>>> latches. Currently, SendInterrupt sets a latch to wake up the target\n>>> process. I wonder if it should be the other way 'round? Move all the\n>>> wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in\n>>> SetLatch, call SendInterrupt to wake up the target process? Somehow that\n>>> feels more natural to me, I think.\n>>\n>> I explored that a little, see attached patch set. It's going towards the\n>> same end state as your patches, I think, but it starts from different\n>> angle. In a nutshell:\n>>\n>> Remove Latch as an abstraction, and replace all use of Latches with\n>> Interrupts. When I originally created the Latch abstraction, I imagined\n>> that we would have different latches for different purposes, but in\n>> reality, almost all code just used the general-purpose \"process latch\".\n>> this patch accepts that reality and replaces the Latch struct directly\n>> with the interrupt mask in PGPROC.\n> \n> Some very initial reactions:\n> \n> * I like it!\n\nOk, here's a new version, with a bunch of bugs and FIXMEs fixed, \ncomments and other polish. A few things remain that I'm not sure about:\n\n- Terminology. We now have storage/interrupt.h and \npostmaster/interrupt.h. They're not the same thing, but there's also \nsome overlap, especially after your patch set is applied.\n\nAside from filenames, \"interrupt\" now means at least two things: a \nwakeup that you can send to a backend with SendInterrupt, and the thing \nthat you check with CHECK_FOR_INTERRUPTS(). They're related, but \ndifferent. To show case that confusion, the patch now contains this gem, \nwhich was a result of mechanically replacing \"latch\" with \"interrupt\":\n\n* We process interrupts whenever the interrupt has been set, so\n* cancel/die interrupts are processed quickly.\n\n\n- Fujii: this replaces the \"recoveryWakeupLatch\" with a separate \ninterrupt type. There was an earlier attempt at replacing \nrecoveryWakeupLatch with the process's regular latch which was reverted, \ncommits ac22929a26, and 00f690a239. I think this solution doesn't suffer \nfrom the same problems as that earlier attempt, but if you have a chance \nto review this, I would appreciate that. In a nutshell, \nINTERRUPT_RECOVERY_CONTINUE interrupt is now used instead of \nrecoveryWakeupLatch, but the places that previously waited just on \nrecoveryWakeupLatch, now wait on both INTERRUPT_GENERAL_WAKEUP, which is \nequivalent to waiting on the process latch, and \nINTERRUPT_RECOVERY_CONTINUE. So those loops should now react more \nquickly to signals like SIGHUP.\n\n- Backwards-compatibility and extensions. This will break any extensions \nthat use Latches. Extensions that just used WaitLatch(MyLatch) or \nsimilar are easy to convert to use latches instead. Or we could keep \naround some backwards-compatibility macros like 0008 here does, to avoid \nthe code churn. However, if an extension is creating its own latches or \ndoing more complicated stuff with them, it gets harder to maintain \nsource-code compatibility for them.\n\nAside from the backwards-compatibility aspect, should we reserve a few \nINTERRUPT_* values for extensions?\n\n\n\n> * This direction seems to fit quite nicely with future ideas about\n> asynchronous network I/O. That may sound unrelated, but imagine that\n> a future version of WaitEventSet is built on Linux io_uring (or\n> Windows iorings, or Windows IOCP, or kqueue), and waits for the kernel\n> to tell you that network data has been transferred directly into a\n> user space buffer. You could wait for the interrupt word to change at\n> the same time by treating it as a futex[1]. Then all that other stuff\n> -- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\n> left is one single word in memory. (That it is possible to do that is\n> not really a coincidence, as our own Mr Freund asked Mr Axboe to add\n> it[2]. The existing latch implementation techniques could be used as\n> fallbacks, but when looked at from the right angle, once you squish\n> all the wakeup reasons into a single word, it's all just an\n> implementation of a multiplexable futex with extra steps.)\n\nCool\n\n> * Speaking of other problems in other threads that might be solved by\n> this redesign, I think I see the outline of some solutions to the\n> problem of different classes of wakeup which you can handle at\n> different times, using masks. There is a tension in a few places\n> where we want to handle some kind of interrupts but not others in\n> localised wait points, which we sort of try to address by holding\n> interrupts or holding cancel interrupts, but it's not satisfying and\n> there are some places where it doesn't work well. Needs a lot more\n> thought, but a basic step would be: after old_interrupt_vector =\n> pg_atomic_fetch_or_u32(interrupt_vector, new_bits), if\n> (old_interrupt_vector & new_bits) == new_bits, then you didn't\n> actually change any bits, so you probably don't really need to wake\n> the other backend. If someone is currently unable to handle that type\n> of interrupt (has ignored, ie not cleared, those bits) or is already\n> in the process of handling it (is currently being rescheduled but\n> hasn't cleared those bits yet), then you don't bother to wake it up.\n> Concretely, it could mean that we avoid some of the useless wakeup\n> storm problems we see in vacuum delays or while executing a query and\n> not in a good place to handle sinval wakeups, etc. These are just\n> some raw thoughts, I am not sure about the bigger picture of that\n> topic yet.\n\nYeah, I expect this work to help with those issues, but also not sure of \nthe details yet.\n\n-- \nHeikki Linnakangas\nNeon (https://neon.tech)","msg_date":"Sat, 31 Aug 2024 01:17:40 +0300","msg_from":"Heikki Linnakangas <hlinnaka@iki.fi>","msg_from_op":false,"msg_subject":"Re: Interrupts vs signals"},{"msg_contents":"On Sat, Aug 31, 2024 at 10:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\n> > * This direction seems to fit quite nicely with future ideas about\n> > asynchronous network I/O. That may sound unrelated, but imagine that\n> > a future version of WaitEventSet is built on Linux io_uring (or\n> > Windows iorings, or Windows IOCP, or kqueue), and waits for the kernel\n> > to tell you that network data has been transferred directly into a\n> > user space buffer. You could wait for the interrupt word to change at\n> > the same time by treating it as a futex[1]. Then all that other stuff\n> > -- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\n> > left is one single word in memory. (That it is possible to do that is\n> > not really a coincidence, as our own Mr Freund asked Mr Axboe to add\n> > it[2]. The existing latch implementation techniques could be used as\n> > fallbacks, but when looked at from the right angle, once you squish\n> > all the wakeup reasons into a single word, it's all just an\n> > implementation of a multiplexable futex with extra steps.)\n>\n> Cool\n\nJust by the way, speaking of future tricks and the connections between\nthis code and other problems in other threads, I wanted to mention\nthat the above thought is also connected to CF #3998. When I started\nworking on this, in parallel I had an experimental patch set using\nfutexes[1] (back then, to try out futexes, I had to patch my OS[2]\nbecause Linux couldn't multiplex them yet, and macOS/*BSD had\nsomething sort of vaguely similar but effectively only usable between\nthreads in one process). I planned to switch to waiting directly on\nthe interrupt vector as a futex when bringing that idea together with\nthe one in this thread, but I guess I assumed we had to keep latches\ntoo since they seemed like such a central concept in PostgreSQL. Your\nidea seems much better, the more I think about it, but maybe only the\ninventor of latches could have the idea of blowing them up :-)\nAnyway, in that same experiment I realised I could wake multiple\nbackends in one system call, which led to more discoveries about the\nnegative interactions between latches and locks, and begat CF #3998\n(SetLatches()). By way of excuse, unfortunately I got blocked in my\nprogress on interrupt vectors for a couple of release cycles by the\nrecovery conflict system, a set of procsignals that were not like the\nothers, and turned out to be broken more or less as a result. That\nwas tricky to fix (CF #3615), leading to journeys into all kinds of\nstrange places like the regex code...\n\n[1] https://github.com/macdice/postgres/commits/kqueue-usermem/\n[2] https://reviews.freebsd.org/D37102\n\n\n","msg_date":"Sat, 31 Aug 2024 12:12:23 +1200","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":true,"msg_subject":"Re: Interrupts vs signals"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\n\\nI wonder if we really need signals to implement interrupts. Given\\nthat they are non-preemptive/cooperative (work happens at the next\\nCFI()), why not just use shared memory flags and latches? That skips\\na bunch of code, global variables and scary warnings about programming\\nin signal handlers.\\n\\nI sketched out some code to try that a few months back, while\\nspeculating about bite-sized subproblems that would come up if each\\nbackend is, one day, a thread.\\n\\nThere are several other conditions that are also handled by\\nCHECK_FOR_INTERRUPTS(), but are not triggered by other backends\\nsending signals, or are set by other signal handlers (SIGALRM,\\nSIGQUIT). One idea is to convert those into \\\"procsignals\\\" too, for\\nconsistency. In the attached, they can be set (ie by the same\\nbackend) with ProcSignalRaise(), but it's possible that in future we\\nmight have a reason for another backend to set them too, so it seems\\nlike a good idea to have a single system, effectively merging the\\nconcepts of \\\"procsignals\\\" and \\\"interrupts\\\".\\n\\nThere are still a few more ad hoc (non-ProcSignal) uses of SIGUSR1 in\\nthe tree. For one thing, we don't allow the postmaster to set\\nlatches; if we gave up on that rule, we wouldn't need the bgworker\\nplease-signal-me thing. Also the logical replication launcher does\\nthe same sort of thing for no apparent reason. Changed in the\\nattached -- mainly so I could demonstrate that check-world passes with\\nSIGUSR1 ignored.\\n\\nThe attached is only experiment grade code: in particular, I didn't\\nquite untangle the recovery conflict flags properly. It's also doing\\nfunction calls where some kind of fast inlined magic is probably\\nrequired, and I probably have a few other details wrong, but I figured\\nit was good enough to demonstrate the concept.\",\n \"msg_date\": \"Thu, 21 Oct 2021 07:55:54 +1300\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-21 07:55:54 +1300, Thomas Munro wrote:\\n> I wonder if we really need signals to implement interrupts. Given\\n> that they are non-preemptive/cooperative (work happens at the next\\n> CFI()), why not just use shared memory flags and latches? That skips\\n> a bunch of code, global variables and scary warnings about programming\\n> in signal handlers.\\n\\nDepending on how you implement them, one difference could be whether / when\\n\\\"slow\\\" system calls (recv, poll, etc) are interrupted.\\n\\nAnother is that that signal handling provides a memory barrier in the\\nreceiving process. For things that rarely change (like most interrupts), it\\ncan be more efficient to move the cost of that out-of-line, instead of\\nincurring them on every check.\\n\\n\\nOne nice thing of putting the state variables into shared memory would be that\\nthat'd allow to see the pending interrupts of other backends for debugging\\npurposes.\\n\\n\\n> One idea is to convert those into \\\"procsignals\\\" too, for\\n> consistency. In the attached, they can be set (ie by the same\\n> backend) with ProcSignalRaise(), but it's possible that in future we\\n> might have a reason for another backend to set them too, so it seems\\n> like a good idea to have a single system, effectively merging the\\n> concepts of \\\"procsignals\\\" and \\\"interrupts\\\".\\n\\nThis seems a bit confusing to me. For one, we need to have interrupts working\\nbefore we have a proc, IIRC. But leaving details like that aside, it just\\nseems a bit backwards to me. I'm on board with other backends directly setting\\ninterrupt flags, but it seems to me that the procsignal stuff should be\\n\\\"client\\\" of the process-local interrupt infrastructure, rather than the other\\nway round.\\n\\n\\n> +bool\\n> +ProcSignalAnyPending(void)\\n> +{\\n> +\\tvolatile ProcSignalSlot *slot = MyProcSignalSlot;\\n> \\n> -\\tif (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))\\n> -\\t\\tRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);\\n> +\\t/* XXX make this static inline? */\\n> +\\t/* XXX point to a dummy entry instead of using NULL to avoid a branch */\\n> +\\treturn slot && slot->pss_signaled;\\n> +}\\n\\nISTM it might be easier to make this stuff efficiently race-free if we made\\nthis a count of pending operations.\\n\\n\\n> @@ -3131,12 +3124,13 @@ ProcessInterrupts(void)\\n> \\t/* OK to accept any interrupts now? */\\n> \\tif (InterruptHoldoffCount != 0 || CritSectionCount != 0)\\n> \\t\\treturn;\\n> -\\tInterruptPending = false;\\n> +\\tProcSignalClearAnyPending();\\n> +\\n> +\\tpg_read_barrier();\\n> \\n> -\\tif (ProcDiePending)\\n> +\\tif (ProcSignalConsume(PROCSIG_DIE))\\n> \\t{\\n\\nI think making all of these checks into function calls isn't great. How about\\nmaking the set of pending signals a bitmask? That'd allow to efficiently check\\na bunch of interrupts together and even where not, it'd just be a single test\\nof the mask, likely already in a register.\\n\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Wed, 20 Oct 2021 12:27:48 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 21, 2021 at 8:27 AM Andres Freund <andres@anarazel.de> wrote:\\n> On 2021-10-21 07:55:54 +1300, Thomas Munro wrote:\\n> > I wonder if we really need signals to implement interrupts. Given\\n> > that they are non-preemptive/cooperative (work happens at the next\\n> > CFI()), why not just use shared memory flags and latches? That skips\\n> > a bunch of code, global variables and scary warnings about programming\\n> > in signal handlers.\\n>\\n> Depending on how you implement them, one difference could be whether / when\\n> \\\"slow\\\" system calls (recv, poll, etc) are interrupted.\\n\\nHopefully by now all such waits are implemented with latch.c facilities?\\n\\n> Another is that that signal handling provides a memory barrier in the\\n> receiving process. For things that rarely change (like most interrupts), it\\n> can be more efficient to move the cost of that out-of-line, instead of\\n> incurring them on every check.\\n\\nAgreed, but in this experiment I was trying out the idea that a memory\\nbarrier is not really needed at all, unless you're about to go to\\nsleep. We already insert one of those before a latch wait. That is,\\nif we see !set->latch->is_set, we do pg_memory_barrier() and check\\nagain, before sleeping, so your next CFI must see the flag. For\\ncomputation loops (sort, hash, query execution, ...), I speculate that\\na relaxed read of memory is fine... you'll see the flag pretty soon,\\nand you certainly won't be allowed to finish your computation and go\\nto sleep.\\n\\n> One nice thing of putting the state variables into shared memory would be that\\n> that'd allow to see the pending interrupts of other backends for debugging\\n> purposes.\\n\\n+1\\n\\n> > One idea is to convert those into \\\"procsignals\\\" too, for\\n> > consistency. In the attached, they can be set (ie by the same\\n> > backend) with ProcSignalRaise(), but it's possible that in future we\\n> > might have a reason for another backend to set them too, so it seems\\n> > like a good idea to have a single system, effectively merging the\\n> > concepts of \\\"procsignals\\\" and \\\"interrupts\\\".\\n>\\n> This seems a bit confusing to me. For one, we need to have interrupts working\\n> before we have a proc, IIRC. But leaving details like that aside, it just\\n> seems a bit backwards to me. I'm on board with other backends directly setting\\n> interrupt flags, but it seems to me that the procsignal stuff should be\\n> \\\"client\\\" of the process-local interrupt infrastructure, rather than the other\\n> way round.\\n\\nHmm. Yeah, I see your point. But I can also think of some arguments\\nfor merging the concepts of local and shared interrupts; see below.\\n\\nIn this new sketch, I tried doing it the other way around. That is,\\ncompletely removing the concept of \\\"ProcSignal\\\", leaving only\\n\\\"Interrupts\\\". Initially, MyPendingInterrupts points to something\\nprivate, and once you're connected to shared memory it points to\\nMyProc->pending_interrupts.\\n\\n> > +bool\\n> > +ProcSignalAnyPending(void)\\n> > +{\\n> > + volatile ProcSignalSlot *slot = MyProcSignalSlot;\\n> >\\n> > - if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))\\n> > - RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);\\n> > + /* XXX make this static inline? */\\n> > + /* XXX point to a dummy entry instead of using NULL to avoid a branch */\\n> > + return slot && slot->pss_signaled;\\n> > +}\\n>\\n> ISTM it might be easier to make this stuff efficiently race-free if we made\\n> this a count of pending operations.\\n\\nHmm, with a unified interrupt system and a bitmap it's not necessary\\nto have a separate flag/counter at all.\\n\\n> > @@ -3131,12 +3124,13 @@ ProcessInterrupts(void)\\n> > /* OK to accept any interrupts now? */\\n> > if (InterruptHoldoffCount != 0 || CritSectionCount != 0)\\n> > return;\\n> > - InterruptPending = false;\\n> > + ProcSignalClearAnyPending();\\n> > +\\n> > + pg_read_barrier();\\n> >\\n> > - if (ProcDiePending)\\n> > + if (ProcSignalConsume(PROCSIG_DIE))\\n> > {\\n>\\n> I think making all of these checks into function calls isn't great. How about\\n> making the set of pending signals a bitmask? That'd allow to efficiently check\\n> a bunch of interrupts together and even where not, it'd just be a single test\\n> of the mask, likely already in a register.\\n\\n+1.\\n\\nSome assorted notes:\\n\\n1. Aside from doing interrupts in this new way, I also have the\\npostmaster setting latches (!) instead of sending ad hoc SIGUSR1 here\\nand there. My main reason for doing that was to be able to chase out\\nall reasons to register a SIGUSR1 handler, so I could prove that\\ncheck-world passes. I like it, though. But maybe it's really a\\nseparate topic.\\n\\n2. I moved this stuff into interrupt.{h,c}. There is nothing left in\\nprocsignal.c except code relating to ProcSignalBarrier. I guess that\\nthing could use another name, anyway. It's a ...\\nSystemInterruptBarrier?\\n\\n3. Child-level SIGINT and SIGTERM handlers probably aren't really\\nnecessary, either: maybe the sender could do\\nInterruptSend(INTERRUPT_{DIE,QUERY_CANCEL}, pgprocno) instead? But\\nperhaps people are attached to being able to send those signals from\\nexternal programs directly to backends.\\n\\n4. Like the above, a SIGALRM handler might need to do eg\\nInterruptRaise(INTERRUPT_STATEMENT_TIMEOUT). That's a problem for\\nsystems using spinlocks (self-deadlock against user context in\\nInterruptRaise()), so I'd need to come up with some flag protocol for\\ndinosaurs to make that safe, OR revert to having these \\\"local only\\\"\\ninterrupts done with separate flags, as you were getting at earlier.\\n\\n5. The reason I prefer to put currently \\\"local only\\\" interrupts into\\nthe same atomic system is that I speculate that ultimately all of the\\nbackend-level signal handlers won't be needed. They all fall into\\nthree categories: (1) could be replaced with these interrupts\\ndirectly, (2) could be replaced by the new timer infrastructure that\\nmultithreaded postgres would need to have to deliver interrupts to the\\nright recipients, (3) are quickdie and can be handled at the\\ncontaining process level. Then the only signal handlers left are top\\nlevel external ones.\\n\\nBut perhaps you're right and I should try reintroducing separate local\\ninterrupts for now. I dunno, I like the simplicity of the unified\\nsystem; if only it weren't for those spinlock-backed atomics.\",\n \"msg_date\": \"Thu, 11 Nov 2021 18:27:09 +1300\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 11, 2021 at 12:27 AM Thomas Munro <thomas.munro@gmail.com> wrote:\\n> > Depending on how you implement them, one difference could be whether / when\\n> > \\\"slow\\\" system calls (recv, poll, etc) are interrupted.\\n>\\n> Hopefully by now all such waits are implemented with latch.c facilities?\\n\\nDo read(), write(), etc. count? Because we certainly have raw calls to\\nthose functions in lots of places.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 11 Nov 2021 09:06:01 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-11-11 09:06:01 -0500, Robert Haas wrote:\\n> On Thu, Nov 11, 2021 at 12:27 AM Thomas Munro <thomas.munro@gmail.com> wrote:\\n> > > Depending on how you implement them, one difference could be whether / when\\n> > > \\\"slow\\\" system calls (recv, poll, etc) are interrupted.\\n> >\\n> > Hopefully by now all such waits are implemented with latch.c facilities?\\n> \\n> Do read(), write(), etc. count? Because we certainly have raw calls to\\n> those functions in lots of places.\\n\\nThey can count, but only when used for network sockets or pipes (\\\"slow\\ndevices\\\" or whatever the posix language is). Disk IO doesn't count as that. So\\nI don't think it'd be a huge issue.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 11 Nov 2021 11:50:00 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 11, 2021 at 2:50 PM Andres Freund <andres@anarazel.de> wrote:\\n> They can count, but only when used for network sockets or pipes (\\\"slow\\n> devices\\\" or whatever the posix language is). Disk IO doesn't count as that. So\\n> I don't think it'd be a huge issue.\\n\\nSomehow the idea that the network is a slow device and the disk a fast\\none does not seem like it's necessarily accurate on modern hardware,\\nbut I guess the spec is what it is.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 11 Nov 2021 15:24:41 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Fri, Nov 12, 2021 at 9:24 AM Robert Haas <robertmhaas@gmail.com> wrote:\\n> On Thu, Nov 11, 2021 at 2:50 PM Andres Freund <andres@anarazel.de> wrote:\\n> > They can count, but only when used for network sockets or pipes (\\\"slow\\n> > devices\\\" or whatever the posix language is). Disk IO doesn't count as that. So\\n> > I don't think it'd be a huge issue.\\n>\\n> Somehow the idea that the network is a slow device and the disk a fast\\n> one does not seem like it's necessarily accurate on modern hardware,\\n> but I guess the spec is what it is.\\n\\n[Somehow I managed to reply to Robert only; let me try that again,\\nthis time to the list...]\\n\\nNetwork filesystems have in the past been confusing because they're\\nboth disk-like and network-like, and also slow as !@#$, which is why\\nthere have been mount point options like \\\"intr\\\", \\\"nointr\\\" (now ignored\\non Linux) to control what happens if you receive an async signal\\nduring a sleepy read/write. But even if you had some kind of\\nDeathstation 9000 that had a switch on the front panel that ignores\\nSA_RESTART and produces EINTR for disk I/O when a signal arrives,\\nPostgreSQL already doesn't work today. Our pread() and pwrite() paths\\nfor data and WAL don't not have a EINTR loops or\\nCHECK_FOR_INTERRUPTS() (we just can't take interrupts in the middle of\\neg a synchronous write), so I think we'd produce an ERROR or PANIC.\\nSo I think disk I/O is irrelevant, and network/pipe I/O is already\\nhandled everywhere via latch.c facilities.\\n\\nIf there are any eg blocking reads on a socket in PostgreSQL, we\\nshould fix that to use latch.c non-blocking techniques, because such a\\nplace is already a place that ignores postmaster death and interrupts.\\nTo be more precise: such a place could of course wake up for EINTR on\\nSIGUSR1 from procsignal.c, and that would no longer happen with my\\npatch, but if we're relying on that anywhere, it's dangerous and\\nunreliable. If SIGUSR1 is delivered right before you enter a blocking\\nread(), you'll sleep waiting for the socket or whatever. That's\\nprecisely the problem that latch.c solves, and why it's already a bug\\nif there are such places.\\n\\n\\n\",\n \"msg_date\": \"Fri, 12 Nov 2021 09:57:38 +1300\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"Here's an updated version of this patch.\\n\\nThe main idea is that SendProcSignal(pid, PROCSIGNAL_XXX, procno)\\nbecomes SendInterrupt(INTERRUPT_XXX, procno), and all the pending\\ninterrupt global variables and pss_procsignalFlags[] go away, along\\nwith the SIGUSR1 handler. The interrupts are compressed into a single\\nbitmap. See commit message for more details.\\n\\nThe patch is failing on Windows CI for reasons I haven't debugged yet,\\nbut I wanted to share what I have so far. Work in progress!\\n\\nHere is my attempt to survey the use of signals and write down what I\\nthink we might do about them all so far, to give the context for this\\npatch:\\n\\nhttps://wiki.postgresql.org/wiki/Signals\\n\\nComments, corrections, edits very welcome.\",\n \"msg_date\": \"Mon, 8 Jul 2024 14:56:38 +1200\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 08/07/2024 05:56, Thomas Munro wrote:\\n> Here's an updated version of this patch.\\n> \\n> The main idea is that SendProcSignal(pid, PROCSIGNAL_XXX, procno)\\n> becomes SendInterrupt(INTERRUPT_XXX, procno), and all the pending\\n> interrupt global variables and pss_procsignalFlags[] go away, along\\n> with the SIGUSR1 handler. The interrupts are compressed into a single\\n> bitmap. See commit message for more details.\\n> \\n> The patch is failing on Windows CI for reasons I haven't debugged yet,\\n> but I wanted to share what I have so far. Work in progress!\\n> \\n> Here is my attempt to survey the use of signals and write down what I\\n> think we might do about them all so far, to give the context for this\\n> patch:\\n> \\n> https://wiki.postgresql.org/wiki/Signals\\n> \\n> Comments, corrections, edits very welcome.\\n\\nNice, thanks!\\n\\n> Background worker state notifications are also changed from raw\\n> kill(SIGUSR1) to SetLatch(). That means that SetLatch() is now called\\n> from the postmaster. The main purpose of including that change is to be\\n> able to remove procsignal_sigusr1_handler completely and set SIGUSR1 to\\n> SIG_IGN, and show the system working.\\n> \\n> XXX Do we need to invent SetLatchRobust() that doesn't trust anything in\\n> shared memory, to be able to set latches from the postmaster?\\n\\nThe patch actually does both: it still does kill(SIGUSR1) and also sets \\nthe latch.\\n\\nI think it would be nice if RegisterDynamicBackgroundWorker() had a \\n\\\"bool notify_me\\\" argument, instead of requiring the caller to set \\n\\\"bgw_notify_pid = MyProcPid\\\" before the call. That's a \\nbackwards-compatibility break, but maybe we should bite the bullet and \\ndo it. Or we could do this in RegisterDynamicBackgroundWorker():\\n\\nif (worker->bgw_notify_pid == MyProcPid)\\n worker->bgw_notify_pgprocno = MyProcNumber;\\n\\nI think we can forbid setting pgw_notify_pid to anything else than 0 or \\nMyProcPid.\\n\\nA SetLatchRobust would be nice. Looking at SetLatch(), I don't think it \\ncan do any damage if you called it on a pointer to garbage, except if \\nthe pointer itself is bogus, then just dereferencing it an cause a \\nsegfault. So it would be nice to have a version specifically designed \\nwith that in mind. For example, it could assume that the Latch's pid is \\nnever legally equal to MyProcPid, because postmaster cannot own any latches.\\n\\nAnother approach would be to move the responsibility of background \\nworker state notifications out of postmaster completely. When a new \\nbackground worker is launched, the worker process itself could send the \\nnotification that it has started. And similarly, when a worker exits, it \\ncould send the notification just before exiting. There's a little race \\ncondition with exiting: if a process is waiting for the bgworker to \\nexit, and launches a new worker immediately when the old one exits, \\nthere will be a brief period when the old and new process are alive at \\nthe same time. The old worker wouldn't be doing anything interesting \\nanymore since it's exiting, but it still counts towards \\nmax_worker_processes, so launching the new process might fail because of \\nhitting the limit. Maybe we should just bump up max_worker_processes. Or \\npostmaster could check PMChildFlags and not count processes that have \\nalready deregistered from PMChildFlags towards the limit.\\n\\n> -volatile uint32 InterruptHoldoffCount = 0;\\n> -volatile uint32 QueryCancelHoldoffCount = 0;\\n> -volatile uint32 CritSectionCount = 0;\\n> +uint32 InterruptHoldoffCount = 0;\\n> +uint32 QueryCancelHoldoffCount = 0;\\n> +uint32 CritSectionCount = 0;\\n\\nI wondered if these are used in PG_TRY-CATCH blocks in a way that would \\nstill require volatile. I couldn't find any such usage by some quick \\ngrepping, so I think we're good, but I thought I'd mention it.\\n\\n> +/*\\n> + * The set of \\\"standard\\\" interrupts that CHECK_FOR_INTERRUPTS() and\\n> + * ProcessInterrupts() handle. These perform work that is safe to run whenever\\n> + * interrupts are not \\\"held\\\". Other kinds of interrupts are only handled at\\n> + * more restricted times.\\n> + */\\n> +#define INTERRUPT_STANDARD_MASK\\t\\t\\t\\t\\t\\t\\t \\\\\\n\\nSome interrupts are missing from this mask:\\n\\n- INTERRUPT_PARALLEL_APPLY_MESSAGE\\n- INTERRUPT_IDLE_STATS_UPDATE_TIMEOUT\\n- INTERRUPT_SINVAL_CATCHUP\\n- INTERRUPT_NOTIFY\\n\\nIs that on purpose?\\n\\n> -/*\\n> - * Because backends sitting idle will not be reading sinval events, we\\n> - * need a way to give an idle backend a swift kick in the rear and make\\n> - * it catch up before the sinval queue overflows and forces it to go\\n> - * through a cache reset exercise. This is done by sending\\n> - * PROCSIG_CATCHUP_INTERRUPT to any backend that gets too far behind.\\n> - *\\n> - * The signal handler will set an interrupt pending flag and will set the\\n> - * processes latch. Whenever starting to read from the client, or when\\n> - * interrupted while doing so, ProcessClientReadInterrupt() will call\\n> - * ProcessCatchupEvent().\\n> - */\\n> -volatile sig_atomic_t catchupInterruptPending = false;\\n\\nWould be nice to move that comment somewhere else rather than remove it \\ncompletely.\\n\\n> --- a/src/backend/storage/lmgr/proc.c\\n> +++ b/src/backend/storage/lmgr/proc.c\\n> @@ -444,6 +444,10 @@ InitProcess(void)\\n> \\tOwnLatch(&MyProc->procLatch);\\n> \\tSwitchToSharedLatch();\\n> \\n> +\\t/*We're now ready to accept interrupts from other processes. */\\n> +\\tpg_atomic_init_u32(&MyProc->pending_interrupts, 0);\\n> +\\tSwitchToSharedInterrupts();\\n> +\\n> \\t/* now that we have a proc, report wait events to shared memory */\\n> \\tpgstat_set_wait_event_storage(&MyProc->wait_event_info);\\n> \\n> @@ -611,6 +615,9 @@ InitAuxiliaryProcess(void)\\n> \\tOwnLatch(&MyProc->procLatch);\\n> \\tSwitchToSharedLatch();\\n> \\n> +\\t/* We're now ready to accept interrupts from other processes. */\\n> +\\tSwitchToSharedInterrupts();\\n> +\\n> \\t/* now that we have a proc, report wait events to shared memory */\\n> \\tpgstat_set_wait_event_storage(&MyProc->wait_event_info);\\n> \\n\\nIs there a reason for the different initialization between a regular \\nbackend and aux process?\\n\\n> +/*\\n> + * Switch to shared memory interrupts. Other backends can send interrupts\\n> + * to this one if they know its ProcNumber.\\n> + */\\n> +void\\n> +SwitchToSharedInterrupts(void)\\n> +{\\n> +\\tpg_atomic_fetch_or_u32(&MyProc->pending_interrupts, pg_atomic_read_u32(MyPendingInterrupts));\\n> +\\tMyPendingInterrupts = &MyProc->pending_interrupts;\\n> +}\\n\\nHmm, I think there's a race condition here (and similarly in \\nSwitchToLocalInterrupts), if the signal handler runs between the \\npg_atomic_fetch_or_u32, and changing MyPendingInterrupts. Maybe \\nsomething like this instead:\\n\\nMyPendingInterrupts = &MyProc->pending_interrupts;\\npg_memory_barrier();\\npg_atomic_fetch_or_u32(&MyProc->pending_interrupts, \\npg_atomic_read_u32(LocalPendingInterrupts));\\n\\nAnd perhaps this should also clear LocalPendingInterrupts, just to be tidy.\\n\\n> @@ -138,7 +139,8 @@\\n> typedef struct ProcState\\n> {\\n> \\t/* procPid is zero in an inactive ProcState array entry. */\\n> -\\tpid_t\\t\\tprocPid;\\t\\t/* PID of backend, for signaling */\\n> +\\tpid_t\\t\\tprocPid;\\t\\t/* pid of backend */\\n> +\\tProcNumber\\tpgprocno;\\t\\t/* for sending interrupts */\\n> \\t/* nextMsgNum is meaningless if procPid == 0 or resetState is true. */\\n> \\tint\\t\\t\\tnextMsgNum;\\t\\t/* next message number to read */\\n> \\tbool\\t\\tresetState;\\t\\t/* backend needs to reset its state */\\n\\nWe can easily remove procPid altogether now that we have pgprocno here. \\nSimilarly with the pid/pgprocno in ReplicationSlot and WalSndState.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Jul 2024 12:38:22 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Mon, Jul 8, 2024 at 5:38 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n> Another approach would be to move the responsibility of background\\n> worker state notifications out of postmaster completely. When a new\\n> background worker is launched, the worker process itself could send the\\n> notification that it has started. And similarly, when a worker exits, it\\n> could send the notification just before exiting. There's a little race\\n> condition with exiting: if a process is waiting for the bgworker to\\n> exit, and launches a new worker immediately when the old one exits,\\n> there will be a brief period when the old and new process are alive at\\n> the same time. The old worker wouldn't be doing anything interesting\\n> anymore since it's exiting, but it still counts towards\\n> max_worker_processes, so launching the new process might fail because of\\n> hitting the limit. Maybe we should just bump up max_worker_processes. Or\\n> postmaster could check PMChildFlags and not count processes that have\\n> already deregistered from PMChildFlags towards the limit.\\n\\nI can testify that the current system is the result of a lot of trial\\nand error. I'm not saying it can't be made better, but my initial\\nattempts at getting this to work (back in the 9.4 era) resembled what\\nyou proposed here, were consequently a lot simpler than what we have\\nnow, and also did not work. Race conditions like you mention here were\\npart of that. Another consideration is that fork() can fail, and in\\nthat case, the process that tried to register the new background\\nworker needs to find out that the background worker won't ever be\\nstarting. Yet another problem is that, even if fork() succeeds, the\\nnew process might fail before it executes any of our code e.g. because\\nit seg faults very early, a case that actually happened to me -\\ninadvertently - while I was testing these facilities. I ended up\\ndeciding that we can't rely on the new process to do anything until\\nit's given us some signal that it is alive and able to carry out its\\nduties. If it dies before telling us that, or never starts in the\\nfirst place, we have to have some other way of finding that out, and\\nit's difficult to see how that can happen without postmaster\\ninvolvement.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Jul 2024 16:18:01 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Mon, Jul 8, 2024 at 9:38 PM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n> The patch actually does both: it still does kill(SIGUSR1) and also sets\\n> the latch.\\n\\nYeah, I had some ideas about supporting old extension code that really\\nwanted a SIGUSR1, but on reflection, the only reason anyone ever wants\\nthat is so that sigusr1_handler can SetLatch(), which pairs with\\nWaitLatch() in WaitForBackgroundWorker*(). Let's go all the way and\\nassume that.\\n\\n> I think it would be nice if RegisterDynamicBackgroundWorker() had a\\n> \\\"bool notify_me\\\" argument, instead of requiring the caller to set\\n> \\\"bgw_notify_pid = MyProcPid\\\" before the call. That's a\\n> backwards-compatibility break, but maybe we should bite the bullet and\\n> do it. Or we could do this in RegisterDynamicBackgroundWorker():\\n>\\n> if (worker->bgw_notify_pid == MyProcPid)\\n> worker->bgw_notify_pgprocno = MyProcNumber;\\n>\\n> I think we can forbid setting pgw_notify_pid to anything else than 0 or\\n> MyProcPid.\\n\\nAnother idea: we could keep the bgw_notify_pid field around for a\\nwhile, documented as unused and due to be removed in future. We could\\nautomatically capture the caller's proc number. So you get latch\\nwakeups by default, which I expect many people want, and most people\\ncould cope with even if they don't want them. If you really really\\ndon't want them, you could set a new flag BGW_NO_NOTIFY.\\n\\nI have now done this part of the change in a new first patch. This\\nparticular use of kill(SIGUSR1) is separate from the ProcSignal\\nremoval, it's just that it relies on ProcSignal's handler's default\\naction of calling SetLatch(). It's needed so the ProcSignal-ectomy\\ncan fully delete sigusr1_handler(), but it's not directly the same\\nthing, so it seemed good to split the patch.\\n\\n> A SetLatchRobust would be nice. Looking at SetLatch(), I don't think it\\n> can do any damage if you called it on a pointer to garbage, except if\\n> the pointer itself is bogus, then just dereferencing it an cause a\\n> segfault. So it would be nice to have a version specifically designed\\n> with that in mind. For example, it could assume that the Latch's pid is\\n> never legally equal to MyProcPid, because postmaster cannot own any latches.\\n\\nYeah I'm starting to think that all we need to do here is range-check\\nthe proc number. Here's a version that adds:\\nProcSetLatch(proc_number). Another idea would be for SetLatch(latch)\\nto sanitise the address of a latch, ie its offset and range.\\n\\nWhat the user really wants to be able to do with this bgworker API, I\\nthink, is wait for a given a handle, which could find a condition\\nvariable + generation in the slot, so that we don't have to register\\nany proc numbers anywhere until we're actually waiting. But *clearly*\\nthe postmaster can't use the condition variable API without risking\\nfollowing corrupted pointers in shared memory. Whereas AFAICT\\nProcSetLatch() from the patched postmaster can't really be corrupted\\nin any new way that it couldn't already be corrupted in master (where\\nit runs in the target process), if we're just a bit paranoid about how\\nwe find our way to the latch.\\n\\nReceiving latch wakeups in the postmaster might be another question,\\nbut I don't think we need to confront that question just yet.\\n\\n> > -volatile uint32 InterruptHoldoffCount = 0;\\n> > -volatile uint32 QueryCancelHoldoffCount = 0;\\n> > -volatile uint32 CritSectionCount = 0;\\n> > +uint32 InterruptHoldoffCount = 0;\\n> > +uint32 QueryCancelHoldoffCount = 0;\\n> > +uint32 CritSectionCount = 0;\\n>\\n> I wondered if these are used in PG_TRY-CATCH blocks in a way that would\\n> still require volatile. I couldn't find any such usage by some quick\\n> grepping, so I think we're good, but I thought I'd mention it.\\n\\nHmm. Still thinking about this.\\n\\n> > +/*\\n> > + * The set of \\\"standard\\\" interrupts that CHECK_FOR_INTERRUPTS() and\\n> > + * ProcessInterrupts() handle. These perform work that is safe to run whenever\\n> > + * interrupts are not \\\"held\\\". Other kinds of interrupts are only handled at\\n> > + * more restricted times.\\n> > + */\\n> > +#define INTERRUPT_STANDARD_MASK \\\\\\n>\\n> Some interrupts are missing from this mask:\\n>\\n> - INTERRUPT_PARALLEL_APPLY_MESSAGE\\n\\nOops, that one ^ is a rebasing mistake. I wrote the ancestor of this\\npatch in 2021, and that new procsignal arrived in 2023, and I put the\\ncode in to handle it, but I forgot to add it to the mask, which gives\\nme an idea (see below)...\\n\\n> - INTERRUPT_IDLE_STATS_UPDATE_TIMEOUT\\n> - INTERRUPT_SINVAL_CATCHUP\\n> - INTERRUPT_NOTIFY\\n>\\n> Is that on purpose?\\n\\nINTERRUPT_SINVAL_CATCHUP and INTERRUPT_NOTIFY are indeed handled\\ndifferently on purpose. In master, they don't set InterruptPending,\\nand they are not handled by regular CHECK_FOR_INTERRUPTS() sites, but\\nin the patch they still need a bit in pending_interrupts, and that is\\nwhat that mask hides from CHECK_FOR_INTERRUPTS(). They are checked\\nexplicitly in ProcessClientReadInterrupt(). I think the idea is that\\nwe can't handle sinval at random places because that might create\\ndangling pointers to cached objects where we don't expect them, and we\\ncan't emit NOTIFY-related protocol messages at random times either.\\n\\nThere is something a little funky about _IDLE_STATS_UPDATE_TIMEOUT,\\nthough. It has a different scheme for running only when idle, where\\nif it opts not to do anything, it doesn't consume the interrupt (a\\nlater CFI() will, but the latch is not set so we might sleep). I was\\nconfused by that. I think I have changed to be more faithful to\\nmaster's behaviour now.\\n\\nHmm, a better terminology for the interupts that CFI handles would be\\ns/standard/regular/, so I have changed that.\\n\\nNew idea: it would be less error-prone if we instead had a mask of\\nthese special cases, of which there are now only two. Tried that way!\\n\\n> > -/*\\n> > - * Because backends sitting idle will not be reading sinval events, we\\n> > - * need a way to give an idle backend a swift kick in the rear and make\\n> > - * it catch up before the sinval queue overflows and forces it to go\\n> > - * through a cache reset exercise. This is done by sending\\n> > - * PROCSIG_CATCHUP_INTERRUPT to any backend that gets too far behind.\\n> > - *\\n> > - * The signal handler will set an interrupt pending flag and will set the\\n> > - * processes latch. Whenever starting to read from the client, or when\\n> > - * interrupted while doing so, ProcessClientReadInterrupt() will call\\n> > - * ProcessCatchupEvent().\\n> > - */\\n> > -volatile sig_atomic_t catchupInterruptPending = false;\\n>\\n> Would be nice to move that comment somewhere else rather than remove it\\n> completely.\\n\\nOK, I moved it to the top of ProcessCatchupInterrupt().\\n\\n> > --- a/src/backend/storage/lmgr/proc.c\\n> > +++ b/src/backend/storage/lmgr/proc.c\\n> > @@ -444,6 +444,10 @@ InitProcess(void)\\n> > OwnLatch(&MyProc->procLatch);\\n> > SwitchToSharedLatch();\\n> >\\n> > + /*We're now ready to accept interrupts from other processes. */\\n> > + pg_atomic_init_u32(&MyProc->pending_interrupts, 0);\\n> > + SwitchToSharedInterrupts();\\n> > +\\n> > /* now that we have a proc, report wait events to shared memory */\\n> > pgstat_set_wait_event_storage(&MyProc->wait_event_info);\\n> >\\n> > @@ -611,6 +615,9 @@ InitAuxiliaryProcess(void)\\n> > OwnLatch(&MyProc->procLatch);\\n> > SwitchToSharedLatch();\\n> >\\n> > + /* We're now ready to accept interrupts from other processes. */\\n> > + SwitchToSharedInterrupts();\\n> > +\\n> > /* now that we have a proc, report wait events to shared memory */\\n> > pgstat_set_wait_event_storage(&MyProc->wait_event_info);\\n> >\\n>\\n> Is there a reason for the different initialization between a regular\\n> backend and aux process?\\n\\nNo. But I thought about something else to fix here. Really we don't\\nwant to switch to shared interrupts until we are ready for CFI() to do\\nstuff. I think that should probably be at the places where master\\nunblocks signals. Otherwise, for example, if someone sends you an\\ninterrupt while you're starting up, something as innocent as\\nelog(DEBUG, ...), which reaches CFI(), might try to do things for\\nwhich the infrastructure is not yet fully set up, for example\\nINTERRUPT_BARRIER.\\n\\nNot done yet, but wanted to share this new version.\\n\\n> > +/*\\n> > + * Switch to shared memory interrupts. Other backends can send interrupts\\n> > + * to this one if they know its ProcNumber.\\n> > + */\\n> > +void\\n> > +SwitchToSharedInterrupts(void)\\n> > +{\\n> > + pg_atomic_fetch_or_u32(&MyProc->pending_interrupts, pg_atomic_read_u32(MyPendingInterrupts));\\n> > + MyPendingInterrupts = &MyProc->pending_interrupts;\\n> > +}\\n>\\n> Hmm, I think there's a race condition here (and similarly in\\n> SwitchToLocalInterrupts), if the signal handler runs between the\\n> pg_atomic_fetch_or_u32, and changing MyPendingInterrupts. Maybe\\n> something like this instead:\\n>\\n> MyPendingInterrupts = &MyProc->pending_interrupts;\\n> pg_memory_barrier();\\n> pg_atomic_fetch_or_u32(&MyProc->pending_interrupts,\\n> pg_atomic_read_u32(LocalPendingInterrupts));\\n\\nYeah, right, done.\\n\\n> And perhaps this should also clear LocalPendingInterrupts, just to be tidy.\\n\\nI used atomic_exchange() to read and clear the bits in one go.\\n\\n> > @@ -138,7 +139,8 @@\\n> > typedef struct ProcState\\n> > {\\n> > /* procPid is zero in an inactive ProcState array entry. */\\n> > - pid_t procPid; /* PID of backend, for signaling */\\n> > + pid_t procPid; /* pid of backend */\\n> > + ProcNumber pgprocno; /* for sending interrupts */\\n> > /* nextMsgNum is meaningless if procPid == 0 or resetState is true. */\\n> > int nextMsgNum; /* next message number to read */\\n> > bool resetState; /* backend needs to reset its state */\\n>\\n> We can easily remove procPid altogether now that we have pgprocno here.\\n\\nSince other things access those values, I propose to remove them in\\nseparate patches.\\n\\n> Similarly with the pid/pgprocno in ReplicationSlot and WalSndState.\\n\\nSame. Those pids show up in user interfaces, so I think they should\\nbe handled in separate patches.\\n\\nNote to self: I need to change some pgprocno to proc_number...\\n\\nThe next problems to remove are, I think, the various SIGUSR2, SIGINT,\\nSIGTERM signals sent by the postmaster. These should clearly become\\nSendInterrupt() or ProcSetLatch(). The problem here is that the\\npostmaster doesn't have the proc numbers yet. One idea is to teach\\nthe postmaster to assign them! Not explored yet.\\n\\nThis version is passing on Windows. I'll create a CF entry. Still\\nwork in progress!\",\n \"msg_date\": \"Wed, 10 Jul 2024 18:48:48 +1200\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 10/07/2024 09:48, Thomas Munro wrote:\\n> On Mon, Jul 8, 2024 at 9:38 PM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n>> The patch actually does both: it still does kill(SIGUSR1) and also sets\\n>> the latch.\\n> \\n> Yeah, I had some ideas about supporting old extension code that really\\n> wanted a SIGUSR1, but on reflection, the only reason anyone ever wants\\n> that is so that sigusr1_handler can SetLatch(), which pairs with\\n> WaitLatch() in WaitForBackgroundWorker*(). Let's go all the way and\\n> assume that.\\n\\n+1\\n\\n>> I think it would be nice if RegisterDynamicBackgroundWorker() had a\\n>> \\\"bool notify_me\\\" argument, instead of requiring the caller to set\\n>> \\\"bgw_notify_pid = MyProcPid\\\" before the call. That's a\\n>> backwards-compatibility break, but maybe we should bite the bullet and\\n>> do it. Or we could do this in RegisterDynamicBackgroundWorker():\\n>>\\n>> if (worker->bgw_notify_pid == MyProcPid)\\n>> worker->bgw_notify_pgprocno = MyProcNumber;\\n>>\\n>> I think we can forbid setting pgw_notify_pid to anything else than 0 or\\n>> MyProcPid.\\n> \\n> Another idea: we could keep the bgw_notify_pid field around for a\\n> while, documented as unused and due to be removed in future. We could\\n> automatically capture the caller's proc number. So you get latch\\n> wakeups by default, which I expect many people want, and most people\\n> could cope with even if they don't want them. If you really really\\n> don't want them, you could set a new flag BGW_NO_NOTIFY.\\n\\nOk. I was going to say that it feels excessive to change the default \\nlike that. However, searching for RegisterDynamicBackgroundWorker() in \\ngithub, I can't actually find any callers that don't set pg_notify_pid. \\nSo yeah, make sense.\\n\\n> I have now done this part of the change in a new first patch. This\\n> particular use of kill(SIGUSR1) is separate from the ProcSignal\\n> removal, it's just that it relies on ProcSignal's handler's default\\n> action of calling SetLatch(). It's needed so the ProcSignal-ectomy\\n> can fully delete sigusr1_handler(), but it's not directly the same\\n> thing, so it seemed good to split the patch.\\n\\nPostmasterMarkPIDForWorkerNotify() is now unused. Which means that \\nbgworker_notify is never set, and BackgroundWorkerStopNotifications() is \\nnever called either.\\n\\n>> A SetLatchRobust would be nice. Looking at SetLatch(), I don't think it\\n>> can do any damage if you called it on a pointer to garbage, except if\\n>> the pointer itself is bogus, then just dereferencing it an cause a\\n>> segfault. So it would be nice to have a version specifically designed\\n>> with that in mind. For example, it could assume that the Latch's pid is\\n>> never legally equal to MyProcPid, because postmaster cannot own any latches.\\n> \\n> Yeah I'm starting to think that all we need to do here is range-check\\n> the proc number. Here's a version that adds:\\n> ProcSetLatch(proc_number). Another idea would be for SetLatch(latch)\\n> to sanitise the address of a latch, ie its offset and range.\\n\\nHmm, I don't think postmaster should trust ProcGlobal->allProcCount either.\\n\\n> The next problems to remove are, I think, the various SIGUSR2, SIGINT,\\n> SIGTERM signals sent by the postmaster. These should clearly become\\n> SendInterrupt() or ProcSetLatch().\\n\\n+1\\n\\n> The problem here is that the\\n> postmaster doesn't have the proc numbers yet. One idea is to teach\\n> the postmaster to assign them! Not explored yet.\\n\\nI've been thinking that we should:\\n\\na) assign every child process a PGPROC entry, and make postmaster \\nresponsible for assigning them like you suggest. We'll need more PGPROC \\nentries, because currently a process doesn't reserve one until \\nauthentication has happened. Or we change that behavior.\\n\\nor\\n\\nb) Use the pmsignal.c slot numbers for this, instead of ProcNumbers. \\nPostmaster already assigns those.\\n\\nI'm kind of leaning towards b) for now, because it feels like a much \\nsmaller patch. In the long run, it would be nice if every child process \\nhad a ProcNumber, though. It was a nice simplification in v17 that we \\ndon't have separate BackendId and ProcNumber anymore; similarly it would \\nbe nice to not have separate PMChildSlot and ProcNumber concepts.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 24 Jul 2024 15:57:58 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Wed, Jul 24, 2024 at 8:58 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n> a) assign every child process a PGPROC entry, and make postmaster\\n> responsible for assigning them like you suggest. We'll need more PGPROC\\n> entries, because currently a process doesn't reserve one until\\n> authentication has happened. Or we change that behavior.\\n\\nI wonder how this works right now. Is there something that limits the\\nnumber of authentication requests that can be in flight concurrently,\\nor is it completely uncapped (except by machine resources)?\\n\\nMy first thought when I read this was that it would be bad to have to\\nput a limit on something that's currently unlimited. But then I\\nstarted thinking that, even if it is currently unlimited, that might\\nbe a bug rather than a feature. If you have hundreds of pending\\nauthentication requests, that just means you're using a lot of machine\\nresources on something that doesn't really help anybody. A machine\\nwith hundreds of authentication-pending connections is possibly\\ngetting DDOS'd and probably getting buried. You'd be better off\\nfocusing the machine's limited resources on the already-established\\nconnections and a more limited number of new connection attempts. If\\nyou accept so many connection attempts that you don't actually have\\nenough memory/CPU/kernel scheduling firepower to complete the\\nauthentication process with any of them, it does nobody any good.\\n\\nI'm not sure what's best to do here; just thinking out loud.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jul 2024 12:56:52 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 29/07/2024 19:56, Robert Haas wrote:\\n> On Wed, Jul 24, 2024 at 8:58 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n>> a) assign every child process a PGPROC entry, and make postmaster\\n>> responsible for assigning them like you suggest. We'll need more PGPROC\\n>> entries, because currently a process doesn't reserve one until\\n>> authentication has happened. Or we change that behavior.\\n> \\n> I wonder how this works right now. Is there something that limits the\\n> number of authentication requests that can be in flight concurrently,\\n> or is it completely uncapped (except by machine resources)?\\n\\n> My first thought when I read this was that it would be bad to have to\\n> put a limit on something that's currently unlimited. But then I\\n> started thinking that, even if it is currently unlimited, that might\\n> be a bug rather than a feature. If you have hundreds of pending\\n> authentication requests, that just means you're using a lot of machine\\n> resources on something that doesn't really help anybody. A machine\\n> with hundreds of authentication-pending connections is possibly\\n> getting DDOS'd and probably getting buried. You'd be better off\\n> focusing the machine's limited resources on the already-established\\n> connections and a more limited number of new connection attempts. If\\n> you accept so many connection attempts that you don't actually have\\n> enough memory/CPU/kernel scheduling firepower to complete the\\n> authentication process with any of them, it does nobody any good.\\n> \\n> I'm not sure what's best to do here; just thinking out loud.\\n\\nYes, there's a limit, roughly 2x max_connections. see \\nMaxLivePostmasterChildren().\\n\\nThere's another issue with that that I was about to post in another \\nthread, but here goes: the MaxLivePostmasterChildren() limit is shared \\nby all regular backends, bgworkers and autovacuum workers. If you open a \\nlot of TCP connections to postmaster and don't send anything to the \\nserver, you exhaust those slots, and the server won't be able to start \\nany autovacuum workers or background workers either. That's not great. I \\nstarted to work on approach b), with separate pools of slots for \\ndifferent kinds of child processes, which fixes that. Stay tuned for a \\npatch.\\n\\nIn addition to that, you can have an unlimited number of \\\"dead-end\\\" \\nbackends, which are doomed to just respond with \\\"sorry, too many \\nclients\\\" error. The only limit on those is the amount of resources \\nneeded for all the processes and a little memory to track them.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jul 2024 20:18:22 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> I wonder how this works right now. Is there something that limits the\\n> number of authentication requests that can be in flight concurrently,\\n> or is it completely uncapped (except by machine resources)?\\n\\nThe former. IIRC, the postmaster won't spawn more than 2X max_connections\\nsubprocesses (don't recall the exact limit, but it's around there).\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jul 2024 13:24:21 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Mon, Jul 29, 2024 at 1:24 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Robert Haas <robertmhaas@gmail.com> writes:\\n> > I wonder how this works right now. Is there something that limits the\\n> > number of authentication requests that can be in flight concurrently,\\n> > or is it completely uncapped (except by machine resources)?\\n>\\n> The former. IIRC, the postmaster won't spawn more than 2X max_connections\\n> subprocesses (don't recall the exact limit, but it's around there).\\n\\nHmm. Not to sidetrack this thread too much, but multiplying by two\\ndoesn't really sound like the right idea to me. The basic idea\\narticulated in the comment for canAcceptConnections() makes sense:\\nsome backends might fail authentication, or might be about to exit, so\\nit makes sense to allow for some slop. But 2X is a lot of slop even on\\na machine with the default max_connections=100, and people with\\nconnection management problems are likely to be running with\\nmax_connections=500 or max_connections=900 or even (insanely)\\nmax_connections=2000. Continuing with a connection attempt because we\\nthink that hundreds or thousands of connections that are ahead of us\\nin the queue might clear out of the way before we need a PGPROC is not\\na good bet.\\n\\nI wonder if we ought to restrict this to a small, flat value, like say\\n50, or by a new GUC that defaults to such a value if a constant seems\\nproblematic. Maybe it doesn't really matter. I'm not sure how much\\nwork we'd save by booting out the doomed connection attempt earlier.\\n\\nThe unlimited number of dead-end backends doesn't sound too great\\neither. I don't have another idea, but presumably resisting DDOS\\nattacks and/or preserving resources for things that still have a\\nchance of working ought to take priority over printing a nicer error\\nmessage from a connection that's doomed to fail anyway.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jul 2024 14:05:18 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 10/07/2024 09:48, Thomas Munro wrote:\\n> The next problems to remove are, I think, the various SIGUSR2, SIGINT,\\n> SIGTERM signals sent by the postmaster. These should clearly become\\n> SendInterrupt() or ProcSetLatch(). The problem here is that the\\n> postmaster doesn't have the proc numbers yet. One idea is to teach\\n> the postmaster to assign them! Not explored yet.\\n\\nWith my latest patches on the \\\"Refactoring postmaster's code to cleanup \\nafter child exit\\\" thread [1], every postmaster child process is assigned \\na slot in the pmsignal.c array, including all the aux processes. If we \\nmoved 'pending_interrupts' and the process Latch to the pmsignal.c \\narray, then you could send an interrupt also to a process that doesn't \\nhave a PGPROC entry. That includes dead-end backends, backends that are \\nstill in authentication, and the syslogger.\\n\\nThat would also make it so that the postmaster would never need to poke \\ninto the procarray. pmsignal.c is already designated as the limited \\npiece of shared memory that is accessed by the postmaster \\n(BackgroundWorkerSlots is the other exception), so it would be kind of \\nnice if all the information that the postmaster needs to send an \\ninterrupt was there. That would mean that where you currently use a \\nProcNumber to identify a process, you'd use an index into the \\nPMSignalState array instead.\\n\\nI don't insist on changing that right now, I think this patch is OK as \\nit is, but that might be a good next step later.\\n\\n[1] \\nhttps://www.postgresql.org/message-id/8f2118b9-79e3-4af7-b2c9-bd5818193ca4%40iki.fi\\n\\nI'm also wondering about the relationship between interrupts and \\nlatches. Currently, SendInterrupt sets a latch to wake up the target \\nprocess. I wonder if it should be the other way 'round? Move all the \\nwakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in \\nSetLatch, call SendInterrupt to wake up the target process? Somehow that \\nfeels more natural to me, I think.\\n\\n> This version is passing on Windows. I'll create a CF entry. Still\\n> work in progress!\\n\\nSome comments on the patch details:\\n\\n> \\t\\tereport(WARNING,\\n> \\t\\t\\t\\t(errmsg(\\\"NOTIFY queue is %.0f%% full\\\", fillDegree * 100),\\n> -\\t\\t\\t\\t (minPid != InvalidPid ?\\n> -\\t\\t\\t\\t errdetail(\\\"The server process with PID %d is among those with \\nthe oldest transactions.\\\", minPid)\\n> +\\t\\t\\t\\t (minPgprocno != INVALID_PROC_NUMBER ?\\n> +\\t\\t\\t\\t errdetail(\\\"The server process with pgprocno %d is among those \\nwith the oldest transactions.\\\", minPgprocno)\\n> \\t\\t\\t\\t : 0),\\n> -\\t\\t\\t\\t (minPid != InvalidPid ?\\n> +\\t\\t\\t\\t (minPgprocno != INVALID_PROC_NUMBER ?\\n> \\t\\t\\t\\t errhint(\\\"The NOTIFY queue cannot be emptied until that process \\nends its current transaction.\\\")\\n> \\t\\t\\t\\t : 0)));\\n\\nThis makes the message less useful to the user, as the ProcNumber isn't \\nexposed to users. With the PID, you can do \\\"pg_terminate_backend(pid)\\\"\\n\\n> diff --git a/src/backend/optimizer/util/pathnode.c \\nb/src/backend/optimizer/util/pathnode.c\\n> index c42742d2c7b..bfb89049020 100644\\n> --- a/src/backend/optimizer/util/pathnode.c\\n> +++ b/src/backend/optimizer/util/pathnode.c\\n> @@ -18,6 +18,7 @@\\n>\\n> #include \\\"foreign/fdwapi.h\\\"\\n> #include \\\"miscadmin.h\\\"\\n> +#include \\\"postmaster/interrupt.h\\\"\\n> #include \\\"nodes/extensible.h\\\"\\n> #include \\\"optimizer/appendinfo.h\\\"\\n> #include \\\"optimizer/clauses.h\\\"\\n\\nmisordered\\n\\n> +\\t * duplicated interrupts later if we switch backx.\\n\\ntypo: backx -> back\\n\\n> -\\tif (IdleInTransactionSessionTimeoutPending)\\n> +\\tif (ConsumeInterrupt(INTERRUPT_IDLE_TRANSACTION_TIMEOUT))\\n> \\t{\\n> \\t\\t/*\\n> \\t\\t * If the GUC has been reset to zero, ignore the signal. This is\\n> @@ -3412,7 +3361,6 @@ ProcessInterrupts(void)\\n> \\t\\t * interrupt. We need to unset the flag before the injection point,\\n> \\t\\t * otherwise we could loop in interrupts checking.\\n> \\t\\t */\\n> -\\t\\tIdleInTransactionSessionTimeoutPending = false;\\n> \\t\\tif (IdleInTransactionSessionTimeout > 0)\\n> \\t\\t{\\n> \\t\\t\\tINJECTION_POINT(\\\"idle-in-transaction-session-timeout\\\");\\n\\nThe \\\"We need to unset the flag..\\\" comment is a bit out of place now, \\nsince the flag was already cleared by ConsumeInterrupt(). Same in the \\nINTERRUPT_TRANSACTION_TIMEOUT and INTERRUPT_IDLE_SESSION_TIMEOUT \\nhandling after this.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 7 Aug 2024 17:59:23 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 07/08/2024 17:59, Heikki Linnakangas wrote:\\n> I'm also wondering about the relationship between interrupts and \\n> latches. Currently, SendInterrupt sets a latch to wake up the target \\n> process. I wonder if it should be the other way 'round? Move all the \\n> wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in \\n> SetLatch, call SendInterrupt to wake up the target process? Somehow that \\n> feels more natural to me, I think.\\n\\nI explored that a little, see attached patch set. It's going towards the \\nsame end state as your patches, I think, but it starts from different \\nangle. In a nutshell:\\n\\nRemove Latch as an abstraction, and replace all use of Latches with \\nInterrupts. When I originally created the Latch abstraction, I imagined \\nthat we would have different latches for different purposes, but in \\nreality, almost all code just used the general-purpose \\\"process latch\\\". \\nthis patch accepts that reality and replaces the Latch struct directly \\nwith the interrupt mask in PGPROC.\\n\\nThis initially defines only two interrupts. INTERRUPT_GENERAL_WAKEUP is \\nthe main one, sending that interrupt to a process replaces setting the \\nprocess's generic process latch in PGPROC:\\n\\n* SetLatch(MyLatch) -> RaiseInterrupt(INTERRUPT_GENERAL_WAKEUP)\\n\\n* SetLatch(&ProcGlobal->allProcs[procno].procLatch) -> \\nSendInterrupt(procno, INTERRUPT_GENERAL_WAKEUP\\n\\n* ResetLatch(MyLatch) -> ClearInterrupt(INTERRUPT_GENERAL_WAKEUP)\\n\\n* WaitLatch(MyLatch) -> WaitInterrupt(1 << INTERRUPT_GENERAL_WAKEUP)\\n\\nThere was only one extra Latch in addition the process's generic \\nprocLatch, the recoveryWakeupLatch. It's replaced by the second \\ninterrupt bit, INTERRUPT_RECOVERY_WAKEUP.\\n\\nThis is complementary or preliminary work to your patch set. All the \\nchanges to replace ProcSignals with different interrupt bits could go on \\ntop of this.\\n\\nThis patch set is work in progress, I'd love to hear your thoughts on \\nthis before I spent more time on this. (Haven't tested on Windows for \\nexample).\\n\\nPatches 0001 - 0006 are just little cleanups and minor refactorings that \\nI think make sense even without the rest of the work, though.\\n\\n0007 is the main patch.\\n\\nPatch 0010 addresses the problem discussed at \\nhttps://www.postgresql.org/message-id/CALDaNm01_KEgHM1tKtgXkCGLJ5209SMSmGw3UmhZbOz365_%3DeA%40mail.gmail.com. \\nOther solutions are discussed on that thread, but while working on \\nthese, I realized that with these new interrupts, it's pretty \\nstraightforward to fix by introducing one more interrupt reason.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\",\n \"msg_date\": \"Sat, 24 Aug 2024 20:17:47 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Sun, Aug 25, 2024 at 5:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n> On 07/08/2024 17:59, Heikki Linnakangas wrote:\\n> > I'm also wondering about the relationship between interrupts and\\n> > latches. Currently, SendInterrupt sets a latch to wake up the target\\n> > process. I wonder if it should be the other way 'round? Move all the\\n> > wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in\\n> > SetLatch, call SendInterrupt to wake up the target process? Somehow that\\n> > feels more natural to me, I think.\\n>\\n> I explored that a little, see attached patch set. It's going towards the\\n> same end state as your patches, I think, but it starts from different\\n> angle. In a nutshell:\\n>\\n> Remove Latch as an abstraction, and replace all use of Latches with\\n> Interrupts. When I originally created the Latch abstraction, I imagined\\n> that we would have different latches for different purposes, but in\\n> reality, almost all code just used the general-purpose \\\"process latch\\\".\\n> this patch accepts that reality and replaces the Latch struct directly\\n> with the interrupt mask in PGPROC.\\n\\nSome very initial reactions:\\n\\n* I like it!\\n\\n* This direction seems to fit quite nicely with future ideas about\\nasynchronous network I/O. That may sound unrelated, but imagine that\\na future version of WaitEventSet is built on Linux io_uring (or\\nWindows iorings, or Windows IOCP, or kqueue), and waits for the kernel\\nto tell you that network data has been transferred directly into a\\nuser space buffer. You could wait for the interrupt word to change at\\nthe same time by treating it as a futex[1]. Then all that other stuff\\n-- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\\nleft is one single word in memory. (That it is possible to do that is\\nnot really a coincidence, as our own Mr Freund asked Mr Axboe to add\\nit[2]. The existing latch implementation techniques could be used as\\nfallbacks, but when looked at from the right angle, once you squish\\nall the wakeup reasons into a single word, it's all just an\\nimplementation of a multiplexable futex with extra steps.)\\n\\n* Speaking of other problems in other threads that might be solved by\\nthis redesign, I think I see the outline of some solutions to the\\nproblem of different classes of wakeup which you can handle at\\ndifferent times, using masks. There is a tension in a few places\\nwhere we want to handle some kind of interrupts but not others in\\nlocalised wait points, which we sort of try to address by holding\\ninterrupts or holding cancel interrupts, but it's not satisfying and\\nthere are some places where it doesn't work well. Needs a lot more\\nthought, but a basic step would be: after old_interrupt_vector =\\npg_atomic_fetch_or_u32(interrupt_vector, new_bits), if\\n(old_interrupt_vector & new_bits) == new_bits, then you didn't\\nactually change any bits, so you probably don't really need to wake\\nthe other backend. If someone is currently unable to handle that type\\nof interrupt (has ignored, ie not cleared, those bits) or is already\\nin the process of handling it (is currently being rescheduled but\\nhasn't cleared those bits yet), then you don't bother to wake it up.\\nConcretely, it could mean that we avoid some of the useless wakeup\\nstorm problems we see in vacuum delays or while executing a query and\\nnot in a good place to handle sinval wakeups, etc. These are just\\nsome raw thoughts, I am not sure about the bigger picture of that\\ntopic yet.\\n\\n* Archeological note on terminology: the reason almost every relation\\ndatabase and all the literature uses the term \\\"latch\\\" for something\\nlike our LWLocks seems to be that latches were/are one of the kinds of\\nsystem-provided mutex on IBM System/370 and modern descendents ie\\nz/OS. Oracle and other systems that started as knock-offs of the IBM\\nSystem R (the original SQL system, of which DB2 is the modern heir)\\ncontinued that terminology, even though they ran on VMS or Unix or\\nwhatever. I would not be sad if we removed our unusual use of the\\nterm latch.\\n\\n[1] https://man7.org/linux/man-pages/man3/io_uring_prep_futex_wait.3.html\\n[2] https://lore.kernel.org/lkml/20230720221858.135240-1-axboe@kernel.dk/\\n\\n\\n\",\n \"msg_date\": \"Mon, 26 Aug 2024 11:05:46 +1200\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On 26/08/2024 02:05, Thomas Munro wrote:\\n> On Sun, Aug 25, 2024 at 5:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n>> On 07/08/2024 17:59, Heikki Linnakangas wrote:\\n>>> I'm also wondering about the relationship between interrupts and\\n>>> latches. Currently, SendInterrupt sets a latch to wake up the target\\n>>> process. I wonder if it should be the other way 'round? Move all the\\n>>> wakeup code, with the signalfd, the self-pipe etc to interrupt.c, and in\\n>>> SetLatch, call SendInterrupt to wake up the target process? Somehow that\\n>>> feels more natural to me, I think.\\n>>\\n>> I explored that a little, see attached patch set. It's going towards the\\n>> same end state as your patches, I think, but it starts from different\\n>> angle. In a nutshell:\\n>>\\n>> Remove Latch as an abstraction, and replace all use of Latches with\\n>> Interrupts. When I originally created the Latch abstraction, I imagined\\n>> that we would have different latches for different purposes, but in\\n>> reality, almost all code just used the general-purpose \\\"process latch\\\".\\n>> this patch accepts that reality and replaces the Latch struct directly\\n>> with the interrupt mask in PGPROC.\\n> \\n> Some very initial reactions:\\n> \\n> * I like it!\\n\\nOk, here's a new version, with a bunch of bugs and FIXMEs fixed, \\ncomments and other polish. A few things remain that I'm not sure about:\\n\\n- Terminology. We now have storage/interrupt.h and \\npostmaster/interrupt.h. They're not the same thing, but there's also \\nsome overlap, especially after your patch set is applied.\\n\\nAside from filenames, \\\"interrupt\\\" now means at least two things: a \\nwakeup that you can send to a backend with SendInterrupt, and the thing \\nthat you check with CHECK_FOR_INTERRUPTS(). They're related, but \\ndifferent. To show case that confusion, the patch now contains this gem, \\nwhich was a result of mechanically replacing \\\"latch\\\" with \\\"interrupt\\\":\\n\\n* We process interrupts whenever the interrupt has been set, so\\n* cancel/die interrupts are processed quickly.\\n\\n\\n- Fujii: this replaces the \\\"recoveryWakeupLatch\\\" with a separate \\ninterrupt type. There was an earlier attempt at replacing \\nrecoveryWakeupLatch with the process's regular latch which was reverted, \\ncommits ac22929a26, and 00f690a239. I think this solution doesn't suffer \\nfrom the same problems as that earlier attempt, but if you have a chance \\nto review this, I would appreciate that. In a nutshell, \\nINTERRUPT_RECOVERY_CONTINUE interrupt is now used instead of \\nrecoveryWakeupLatch, but the places that previously waited just on \\nrecoveryWakeupLatch, now wait on both INTERRUPT_GENERAL_WAKEUP, which is \\nequivalent to waiting on the process latch, and \\nINTERRUPT_RECOVERY_CONTINUE. So those loops should now react more \\nquickly to signals like SIGHUP.\\n\\n- Backwards-compatibility and extensions. This will break any extensions \\nthat use Latches. Extensions that just used WaitLatch(MyLatch) or \\nsimilar are easy to convert to use latches instead. Or we could keep \\naround some backwards-compatibility macros like 0008 here does, to avoid \\nthe code churn. However, if an extension is creating its own latches or \\ndoing more complicated stuff with them, it gets harder to maintain \\nsource-code compatibility for them.\\n\\nAside from the backwards-compatibility aspect, should we reserve a few \\nINTERRUPT_* values for extensions?\\n\\n\\n\\n> * This direction seems to fit quite nicely with future ideas about\\n> asynchronous network I/O. That may sound unrelated, but imagine that\\n> a future version of WaitEventSet is built on Linux io_uring (or\\n> Windows iorings, or Windows IOCP, or kqueue), and waits for the kernel\\n> to tell you that network data has been transferred directly into a\\n> user space buffer. You could wait for the interrupt word to change at\\n> the same time by treating it as a futex[1]. Then all that other stuff\\n> -- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\\n> left is one single word in memory. (That it is possible to do that is\\n> not really a coincidence, as our own Mr Freund asked Mr Axboe to add\\n> it[2]. The existing latch implementation techniques could be used as\\n> fallbacks, but when looked at from the right angle, once you squish\\n> all the wakeup reasons into a single word, it's all just an\\n> implementation of a multiplexable futex with extra steps.)\\n\\nCool\\n\\n> * Speaking of other problems in other threads that might be solved by\\n> this redesign, I think I see the outline of some solutions to the\\n> problem of different classes of wakeup which you can handle at\\n> different times, using masks. There is a tension in a few places\\n> where we want to handle some kind of interrupts but not others in\\n> localised wait points, which we sort of try to address by holding\\n> interrupts or holding cancel interrupts, but it's not satisfying and\\n> there are some places where it doesn't work well. Needs a lot more\\n> thought, but a basic step would be: after old_interrupt_vector =\\n> pg_atomic_fetch_or_u32(interrupt_vector, new_bits), if\\n> (old_interrupt_vector & new_bits) == new_bits, then you didn't\\n> actually change any bits, so you probably don't really need to wake\\n> the other backend. If someone is currently unable to handle that type\\n> of interrupt (has ignored, ie not cleared, those bits) or is already\\n> in the process of handling it (is currently being rescheduled but\\n> hasn't cleared those bits yet), then you don't bother to wake it up.\\n> Concretely, it could mean that we avoid some of the useless wakeup\\n> storm problems we see in vacuum delays or while executing a query and\\n> not in a good place to handle sinval wakeups, etc. These are just\\n> some raw thoughts, I am not sure about the bigger picture of that\\n> topic yet.\\n\\nYeah, I expect this work to help with those issues, but also not sure of \\nthe details yet.\\n\\n-- \\nHeikki Linnakangas\\nNeon (https://neon.tech)\",\n \"msg_date\": \"Sat, 31 Aug 2024 01:17:40 +0300\",\n \"msg_from\": \"Heikki Linnakangas <hlinnaka@iki.fi>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n },\n {\n \"msg_contents\": \"On Sat, Aug 31, 2024 at 10:17 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:\\n> > * This direction seems to fit quite nicely with future ideas about\\n> > asynchronous network I/O. That may sound unrelated, but imagine that\\n> > a future version of WaitEventSet is built on Linux io_uring (or\\n> > Windows iorings, or Windows IOCP, or kqueue), and waits for the kernel\\n> > to tell you that network data has been transferred directly into a\\n> > user space buffer. You could wait for the interrupt word to change at\\n> > the same time by treating it as a futex[1]. Then all that other stuff\\n> > -- signalfd, is_set, maybe_sleeping -- just goes away, and all we have\\n> > left is one single word in memory. (That it is possible to do that is\\n> > not really a coincidence, as our own Mr Freund asked Mr Axboe to add\\n> > it[2]. The existing latch implementation techniques could be used as\\n> > fallbacks, but when looked at from the right angle, once you squish\\n> > all the wakeup reasons into a single word, it's all just an\\n> > implementation of a multiplexable futex with extra steps.)\\n>\\n> Cool\\n\\nJust by the way, speaking of future tricks and the connections between\\nthis code and other problems in other threads, I wanted to mention\\nthat the above thought is also connected to CF #3998. When I started\\nworking on this, in parallel I had an experimental patch set using\\nfutexes[1] (back then, to try out futexes, I had to patch my OS[2]\\nbecause Linux couldn't multiplex them yet, and macOS/*BSD had\\nsomething sort of vaguely similar but effectively only usable between\\nthreads in one process). I planned to switch to waiting directly on\\nthe interrupt vector as a futex when bringing that idea together with\\nthe one in this thread, but I guess I assumed we had to keep latches\\ntoo since they seemed like such a central concept in PostgreSQL. Your\\nidea seems much better, the more I think about it, but maybe only the\\ninventor of latches could have the idea of blowing them up :-)\\nAnyway, in that same experiment I realised I could wake multiple\\nbackends in one system call, which led to more discoveries about the\\nnegative interactions between latches and locks, and begat CF #3998\\n(SetLatches()). By way of excuse, unfortunately I got blocked in my\\nprogress on interrupt vectors for a couple of release cycles by the\\nrecovery conflict system, a set of procsignals that were not like the\\nothers, and turned out to be broken more or less as a result. That\\nwas tricky to fix (CF #3615), leading to journeys into all kinds of\\nstrange places like the regex code...\\n\\n[1] https://github.com/macdice/postgres/commits/kqueue-usermem/\\n[2] https://reviews.freebsd.org/D37102\\n\\n\\n\",\n \"msg_date\": \"Sat, 31 Aug 2024 12:12:23 +1200\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Interrupts vs signals\"\n }\n]","isConversational":false}}},{"rowIdx":52975,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Attached is a series of patches that address some performance and\ncorrectness problems we've recently identified in pg_dump.\n\nPatch 0001 refactors the way pg_dump keeps track of which \"components\"\n(definition, data, comment, ACL, etc) of a dumpable object need to be\ndumped. The problem addressed here is that the current coding breaks\nthe intended optimization that we don't run pg_dump's secondary data\ncollection queries for objects we're not actually going to dump.\nThat's because we initialize DumpableObject.dump to DUMP_COMPONENT_ALL\n(0xFFFF), and then we're not very careful about clearing meaningless\nbits out of that. That leads to the bitmask not being zero when it's\ntested at the start of a per-object dump function such as dumpFunc(),\neven though DUMP_COMPONENT_DEFINITION might be clear and the object\nmight not have any comment, security label, or ACL. An example\nof the problem here is that we'll end up running through dumpFunc()\nfor every function defined in an extension, even though the only\nones we'd print anything for are those with modified ACLs. In a\ndatabase with a lot of extensions, that results in a lot of useless\nqueries and consequent performance problems [1].\n\nThere are a couple of ways we could rewrite this, but what seemed\nto me to be the clearest and most robust is to separate\nDumpableObject.dump into two bitmasks, one recording the components\nwe've requested to dump and the other recording the components we've\nactually found the object to possess. (The existing logic conflates\nthese purposes by setting and later clearing bits, which I think is\nconfusing and also bug-prone.) Then, when we reach the point where we\nneed to decide if there's anything to do, we can AND those two masks\ntogether to derive the set of things we are really going to dump.\n\nSo the patch adds a \"components\" field with the same bits that \"dump\"\nhas, and arranges to set appropriate bits of that field as we discover\nthat objects have comments, ACLs, etc. (I wonder if we should rename\n\"dump\", perhaps to \"requests\" or the like. But I didn't do so here.)\nIt's straightforward other than that, with just a few things maybe\nworthy of note:\n1. collectComments and collectSecLabels are now run unconditionally,\nnot on-demand, because we need those bit-setting actions to happen\nbefore we start dumping objects.\n2. I had to add collection of pg_class.reltype so that when we find\na comment or seclabel for a composite type's column, we can redirect\nthe bit-setting action from the pg_class entry to the pg_type entry.\n3. Testing for no-components-to-dump is now centralized in\ndumpDumpableObject(), instead of each dumpXXX function doing it.\n\n\nPatch 0002 rethinks the way we handle dumping of ACLs. My main\ngoal here was to get rid of the expensive sub-selects that the\npg_init_privs patch added. The core idea is to drop all of those\nin favor of just reading pg_init_privs once and loading the\ninformation into the DumpableObjects, much the same way as we\nhandle comments and seclabels. I also realized that that patch's\ninsistence on doing assembly/disassembly of ACLs in SQL was a big\nperformance loser. We can calculate the delta between two ACLs\nright in buildACLCommands, just by doing string comparisons after\nwe've disassembled the aclitems array into elements, so it's really\npretty cheap.\n\nThis also led me to the conclusion that it was a bad idea to have\npreserved the \"old\" (pre-9.6) logic in buildACLCommands. The new\napproach of calculating \"add\" and \"remove\" lists as deltas from an\nacldefault() value works perfectly well before 9.6, at least for\nbranches back to 9.2 where acldefault() was added. For older servers,\nI thought briefly about putting hard-wired knowledge of the older\nbranches' default ACLs into dumputils.c, but rejected that in favor of\nemitting REVOKE ALL and then emitting all the ACL's items when we are\nlacking acldefault() results. This turns out to be just as efficient,\nand sometimes more so, as what the old code was doing. For example,\ncomparing pg_dump of the 9.1 regression database between old and new\nlogic, the only difference is\n\n@@ -60,9 +60,7 @@\n -- Name: SCHEMA public; Type: ACL; Schema: -; Owner: postgres\n --\n \n-REVOKE ALL ON SCHEMA public FROM PUBLIC;\n-REVOKE ALL ON SCHEMA public FROM postgres;\n-GRANT ALL ON SCHEMA public TO postgres;\n+REVOKE USAGE ON SCHEMA public FROM PUBLIC;\n GRANT ALL ON SCHEMA public TO PUBLIC;\n\nfor a net savings of two commands. The REVOKE USAGE appears because\nof the hacks Noah added in a7a7be1f2 and b073c3ccd to cause pg_dump\nto believe that schema public has a specific initprivs value even\nwhen it doesn't. In HEAD, that code only triggers for dumps from\nservers >= 9.6, but this patch makes it apply before that too, which\nseems correct to me. A target server >= v15 is going to have that\nACL for the public schema, no matter what the source version is.\n\n(BTW, to replicate that behavior I ended up having to write some\nclient-side functions to construct the text form of an aclitems array.\nThe duplication of logic with aclitemout() is a bit annoying. Not\nsure if it's worth trying to refactor to combine code.)\n\n0002 does not yet incorporate any logic change corresponding to\nthe bug fix under discussion at [2], but it will be easy to add.\nI left that out for now so as not to change any test results.\n\n\nLastly, patch 0003 addresses the concern I raised at [3] that it's\nunsafe to call pg_get_partkeydef() and pg_get_expr(relpartbound)\nin getTables(). Looking closer I realized that we can't cast\npg_class.reloftype to regtype at that point either, since regtypeout\nis going to notice if the type has been concurrently dropped.\n\nIn [3] I'd imagined that we could just delay those calls to a second\nquery in getTables(), but that doesn't work at all: if we apply\nthese functions to every row of pg_class, we still risk failure\nagainst any relation that we didn't lock. So there seems little\nalternative but to push these functions out to secondary queries\nexecuted later.\n\nArguably, 0003 is a bug fix that we should consider back-patching.\nHowever, I've not heard field reports of the problems it fixes,\nso maybe there's no need to bother.\n\n\nPutting all of this together, I did some performance measurements\ncomparing HEAD pg_dump to pg_dump with these three patches. On\nmy machine, using the current regression database as a test case,\nI find that \"pg_dump -s regression >/dev/null\" requires 1.21 sec\non HEAD and 0.915 sec with these patches, or about 24% faster.\nEven more importantly, the time to execute getTables' query drops\nfrom 129 ms to 16 ms. Since that's the window before we can start\nto acquire table locks, making it as short as possible is useful.\n\nTo have another data point, I also experimented with a database\nconstructed like this:\n\ndo $$\nbegin\n for i in 1..2500 loop\n execute 'create table tst' || i || ' (f1 int primary key, f2 text)';\n end loop;\nend $$;\n\nFor that, \"pg_dump -s\" required 4.94 sec vs 4.38 sec, or about 11%\nfaster, and the getTables query dropped from 316 ms to 41 ms.\n\nThere's some other micro-optimizations I'm thinking about, but this\nprobably gets most of the available win, and it seems like a coherent\nset of changes to present at once.\n\n\t\t\tregards, tom lane\n\n[1] https://www.postgresql.org/message-id/1414363.1630341759%40sss.pgh.pa.us\n[2] https://www.postgresql.org/message-id/flat/CAA3qoJnr2%2B1dVJObNtfec%3DqW4Z0nz%3DA9%2Br5bZKoTSy5RDjskMw%40mail.gmail.com\n[3] https://www.postgresql.org/message-id/1462940.1634496313%40sss.pgh.pa.us","msg_date":"Wed, 20 Oct 2021 17:14:45 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Assorted improvements in pg_dump"}],"string":"[\n {\n \"msg_contents\": \"Attached is a series of patches that address some performance and\\ncorrectness problems we've recently identified in pg_dump.\\n\\nPatch 0001 refactors the way pg_dump keeps track of which \\\"components\\\"\\n(definition, data, comment, ACL, etc) of a dumpable object need to be\\ndumped. The problem addressed here is that the current coding breaks\\nthe intended optimization that we don't run pg_dump's secondary data\\ncollection queries for objects we're not actually going to dump.\\nThat's because we initialize DumpableObject.dump to DUMP_COMPONENT_ALL\\n(0xFFFF), and then we're not very careful about clearing meaningless\\nbits out of that. That leads to the bitmask not being zero when it's\\ntested at the start of a per-object dump function such as dumpFunc(),\\neven though DUMP_COMPONENT_DEFINITION might be clear and the object\\nmight not have any comment, security label, or ACL. An example\\nof the problem here is that we'll end up running through dumpFunc()\\nfor every function defined in an extension, even though the only\\nones we'd print anything for are those with modified ACLs. In a\\ndatabase with a lot of extensions, that results in a lot of useless\\nqueries and consequent performance problems [1].\\n\\nThere are a couple of ways we could rewrite this, but what seemed\\nto me to be the clearest and most robust is to separate\\nDumpableObject.dump into two bitmasks, one recording the components\\nwe've requested to dump and the other recording the components we've\\nactually found the object to possess. (The existing logic conflates\\nthese purposes by setting and later clearing bits, which I think is\\nconfusing and also bug-prone.) Then, when we reach the point where we\\nneed to decide if there's anything to do, we can AND those two masks\\ntogether to derive the set of things we are really going to dump.\\n\\nSo the patch adds a \\\"components\\\" field with the same bits that \\\"dump\\\"\\nhas, and arranges to set appropriate bits of that field as we discover\\nthat objects have comments, ACLs, etc. (I wonder if we should rename\\n\\\"dump\\\", perhaps to \\\"requests\\\" or the like. But I didn't do so here.)\\nIt's straightforward other than that, with just a few things maybe\\nworthy of note:\\n1. collectComments and collectSecLabels are now run unconditionally,\\nnot on-demand, because we need those bit-setting actions to happen\\nbefore we start dumping objects.\\n2. I had to add collection of pg_class.reltype so that when we find\\na comment or seclabel for a composite type's column, we can redirect\\nthe bit-setting action from the pg_class entry to the pg_type entry.\\n3. Testing for no-components-to-dump is now centralized in\\ndumpDumpableObject(), instead of each dumpXXX function doing it.\\n\\n\\nPatch 0002 rethinks the way we handle dumping of ACLs. My main\\ngoal here was to get rid of the expensive sub-selects that the\\npg_init_privs patch added. The core idea is to drop all of those\\nin favor of just reading pg_init_privs once and loading the\\ninformation into the DumpableObjects, much the same way as we\\nhandle comments and seclabels. I also realized that that patch's\\ninsistence on doing assembly/disassembly of ACLs in SQL was a big\\nperformance loser. We can calculate the delta between two ACLs\\nright in buildACLCommands, just by doing string comparisons after\\nwe've disassembled the aclitems array into elements, so it's really\\npretty cheap.\\n\\nThis also led me to the conclusion that it was a bad idea to have\\npreserved the \\\"old\\\" (pre-9.6) logic in buildACLCommands. The new\\napproach of calculating \\\"add\\\" and \\\"remove\\\" lists as deltas from an\\nacldefault() value works perfectly well before 9.6, at least for\\nbranches back to 9.2 where acldefault() was added. For older servers,\\nI thought briefly about putting hard-wired knowledge of the older\\nbranches' default ACLs into dumputils.c, but rejected that in favor of\\nemitting REVOKE ALL and then emitting all the ACL's items when we are\\nlacking acldefault() results. This turns out to be just as efficient,\\nand sometimes more so, as what the old code was doing. For example,\\ncomparing pg_dump of the 9.1 regression database between old and new\\nlogic, the only difference is\\n\\n@@ -60,9 +60,7 @@\\n -- Name: SCHEMA public; Type: ACL; Schema: -; Owner: postgres\\n --\\n \\n-REVOKE ALL ON SCHEMA public FROM PUBLIC;\\n-REVOKE ALL ON SCHEMA public FROM postgres;\\n-GRANT ALL ON SCHEMA public TO postgres;\\n+REVOKE USAGE ON SCHEMA public FROM PUBLIC;\\n GRANT ALL ON SCHEMA public TO PUBLIC;\\n\\nfor a net savings of two commands. The REVOKE USAGE appears because\\nof the hacks Noah added in a7a7be1f2 and b073c3ccd to cause pg_dump\\nto believe that schema public has a specific initprivs value even\\nwhen it doesn't. In HEAD, that code only triggers for dumps from\\nservers >= 9.6, but this patch makes it apply before that too, which\\nseems correct to me. A target server >= v15 is going to have that\\nACL for the public schema, no matter what the source version is.\\n\\n(BTW, to replicate that behavior I ended up having to write some\\nclient-side functions to construct the text form of an aclitems array.\\nThe duplication of logic with aclitemout() is a bit annoying. Not\\nsure if it's worth trying to refactor to combine code.)\\n\\n0002 does not yet incorporate any logic change corresponding to\\nthe bug fix under discussion at [2], but it will be easy to add.\\nI left that out for now so as not to change any test results.\\n\\n\\nLastly, patch 0003 addresses the concern I raised at [3] that it's\\nunsafe to call pg_get_partkeydef() and pg_get_expr(relpartbound)\\nin getTables(). Looking closer I realized that we can't cast\\npg_class.reloftype to regtype at that point either, since regtypeout\\nis going to notice if the type has been concurrently dropped.\\n\\nIn [3] I'd imagined that we could just delay those calls to a second\\nquery in getTables(), but that doesn't work at all: if we apply\\nthese functions to every row of pg_class, we still risk failure\\nagainst any relation that we didn't lock. So there seems little\\nalternative but to push these functions out to secondary queries\\nexecuted later.\\n\\nArguably, 0003 is a bug fix that we should consider back-patching.\\nHowever, I've not heard field reports of the problems it fixes,\\nso maybe there's no need to bother.\\n\\n\\nPutting all of this together, I did some performance measurements\\ncomparing HEAD pg_dump to pg_dump with these three patches. On\\nmy machine, using the current regression database as a test case,\\nI find that \\\"pg_dump -s regression >/dev/null\\\" requires 1.21 sec\\non HEAD and 0.915 sec with these patches, or about 24% faster.\\nEven more importantly, the time to execute getTables' query drops\\nfrom 129 ms to 16 ms. Since that's the window before we can start\\nto acquire table locks, making it as short as possible is useful.\\n\\nTo have another data point, I also experimented with a database\\nconstructed like this:\\n\\ndo $$\\nbegin\\n for i in 1..2500 loop\\n execute 'create table tst' || i || ' (f1 int primary key, f2 text)';\\n end loop;\\nend $$;\\n\\nFor that, \\\"pg_dump -s\\\" required 4.94 sec vs 4.38 sec, or about 11%\\nfaster, and the getTables query dropped from 316 ms to 41 ms.\\n\\nThere's some other micro-optimizations I'm thinking about, but this\\nprobably gets most of the available win, and it seems like a coherent\\nset of changes to present at once.\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://www.postgresql.org/message-id/1414363.1630341759%40sss.pgh.pa.us\\n[2] https://www.postgresql.org/message-id/flat/CAA3qoJnr2%2B1dVJObNtfec%3DqW4Z0nz%3DA9%2Br5bZKoTSy5RDjskMw%40mail.gmail.com\\n[3] https://www.postgresql.org/message-id/1462940.1634496313%40sss.pgh.pa.us\",\n \"msg_date\": \"Wed, 20 Oct 2021 17:14:45 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Assorted improvements in pg_dump\"\n }\n]","isConversational":false}}},{"rowIdx":52976,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Remove unused wait events.\n\nCommit 464824323e introduced the wait events which were neither used by\nthat commit nor by follow-up commits for that work.\n\nAuthor: Masahiro Ikeda\nBackpatch-through: 14, where it was introduced\nDiscussion: https://postgr.es/m/ff077840-3ab2-04dd-bbe4-4f5dfd2ad481@oss.nttdata.com\n\nBranch\n------\nREL_14_STABLE\n\nDetails\n-------\nhttps://git.postgresql.org/pg/commitdiff/671eb8f34404d24c8f16ae40e94becb38afd93bb\n\nModified Files\n--------------\ndoc/src/sgml/monitoring.sgml | 16 ----------------\nsrc/backend/utils/activity/wait_event.c | 12 ------------\nsrc/include/utils/wait_event.h | 6 +-----\n3 files changed, 1 insertion(+), 33 deletions(-)","msg_date":"Thu, 21 Oct 2021 02:52:04 +0000","msg_from":"Amit Kapila <akapila@postgresql.org>","msg_from_op":true,"msg_subject":"pgsql: Remove unused wait events."},{"msg_contents":"On Wed, Oct 20, 2021 at 10:52 PM Amit Kapila <akapila@postgresql.org> wrote:\n> Remove unused wait events.\n>\n> Commit 464824323e introduced the wait events which were neither used by\n> that commit nor by follow-up commits for that work.\n\nThis commit forces a recompile of every extension that knows about the\ninteger values assigned to the enums in WaitEventIO. I know of 2\nextensions that are affected by this. I think that it should be\nreverted in v14 and kept only in master.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 12:17:53 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> On Wed, Oct 20, 2021 at 10:52 PM Amit Kapila <akapila@postgresql.org> wrote:\n>> Remove unused wait events.\n\n> This commit forces a recompile of every extension that knows about the\n> integer values assigned to the enums in WaitEventIO. I know of 2\n> extensions that are affected by this. I think that it should be\n> reverted in v14 and kept only in master.\n\nUm ... the removed symbols were at the end of the WaitEventIO enum,\nso is there really an ABI break? I suppose if an extension contains\nactual references to the removed symbols, it would fail to recompile,\nwhich'd be annoying for a released branch.\n\nOn the whole, I agree that this patch had no business being committed\nto v14.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 12:38:38 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On Mon, Oct 25, 2021 at 12:38 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Um ... the removed symbols were at the end of the WaitEventIO enum,\n> so is there really an ABI break? I suppose if an extension contains\n> actual references to the removed symbols, it would fail to recompile,\n> which'd be annoying for a released branch.\n\nI think that you're right. I believe one of the two extensions I know\nabout hopes that values won't be renumbered or become invalid across\nminor releases, and the other contains specific references to these\nparticular constants.\n\nNow of course it is always arguable whether or not anything that some\nextension is doing ought to be deemed an acceptable use of the\nfacilities provided by core, and how much stability ought to be\nguaranteed. But while I agree it's good to remove unused stuff in the\nmaster, it doesn't seem like we really need to back-patch it.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 13:10:25 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> ... But while I agree it's good to remove unused stuff in the\n> master, it doesn't seem like we really need to back-patch it.\n\nYeah, exactly. I don't see any benefit that's commensurate with\neven a small risk of breaking extensions --- and apparently, in\nthis case that's not a risk but a certainty.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 13:18:26 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"> On 25 Oct 2021, at 19:18, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> \n> Robert Haas <robertmhaas@gmail.com> writes:\n>> ... But while I agree it's good to remove unused stuff in the\n>> master, it doesn't seem like we really need to back-patch it.\n> \n> Yeah, exactly. I don't see any benefit that's commensurate with\n> even a small risk of breaking extensions --- and apparently, in\n> this case that's not a risk but a certainty.\n\nSince this will cause integer values to have different textual enum value\nrepresentations in 14 and 15+, do we want to skip two numbers by assigning the\nnext wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\nOr enum integer reuse not something we guarantee against across major versions?\n\n--\nDaniel Gustafsson\t\thttps://vmware.com/\n\n\n\n","msg_date":"Mon, 25 Oct 2021 19:34:37 +0200","msg_from":"Daniel Gustafsson <daniel@yesql.se>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"Daniel Gustafsson <daniel@yesql.se> writes:\n> Since this will cause integer values to have different textual enum value\n> representations in 14 and 15+, do we want to skip two numbers by assigning the\n> next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\n> Or enum integer reuse not something we guarantee against across major versions?\n\nWe require a recompile across major versions. I don't see a reason why\nthis particular enum needs more stability than any other one.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 13:39:44 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On 2021-10-25 13:39:44 -0400, Tom Lane wrote:\n> Daniel Gustafsson <daniel@yesql.se> writes:\n> > Since this will cause integer values to have different textual enum value\n> > representations in 14 and 15+, do we want to skip two numbers by assigning the\n> > next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\n> > Or enum integer reuse not something we guarantee against across major versions?\n> \n> We require a recompile across major versions. I don't see a reason why\n> this particular enum needs more stability than any other one.\n\n+1. That'd end up pushing us to be more conservative about defining new wait\nevents, which I think would be bad tradeoff.\n\n\n","msg_date":"Mon, 25 Oct 2021 11:01:22 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"> On 25 Oct 2021, at 20:01, Andres Freund <andres@anarazel.de> wrote:\n> \n> On 2021-10-25 13:39:44 -0400, Tom Lane wrote:\n>> Daniel Gustafsson <daniel@yesql.se> writes:\n>>> Since this will cause integer values to have different textual enum value\n>>> representations in 14 and 15+, do we want to skip two numbers by assigning the\n>>> next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\n>>> Or enum integer reuse not something we guarantee against across major versions?\n>> \n>> We require a recompile across major versions. I don't see a reason why\n>> this particular enum needs more stability than any other one.\n> \n> +1. That'd end up pushing us to be more conservative about defining new wait\n> events, which I think would be bad tradeoff.\n\nFair enough, makes sense.\n\n--\nDaniel Gustafsson\t\thttps://vmware.com/\n\n\n\n","msg_date":"Mon, 25 Oct 2021 20:03:54 +0200","msg_from":"Daniel Gustafsson <daniel@yesql.se>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On Mon, Oct 25, 2021 at 01:18:26PM -0400, Tom Lane wrote:\n> Robert Haas <robertmhaas@gmail.com> writes:\n>> ... But while I agree it's good to remove unused stuff in the\n>> master, it doesn't seem like we really need to back-patch it.\n> \n> Yeah, exactly. I don't see any benefit that's commensurate with\n> even a small risk of breaking extensions --- and apparently, in\n> this case that's not a risk but a certainty.\n\n+1.\n--\nMichael","msg_date":"Tue, 26 Oct 2021 10:19:53 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On Tue, Oct 26, 2021 at 6:50 AM Michael Paquier <michael@paquier.xyz> wrote:\n>\n> On Mon, Oct 25, 2021 at 01:18:26PM -0400, Tom Lane wrote:\n> > Robert Haas <robertmhaas@gmail.com> writes:\n> >> ... But while I agree it's good to remove unused stuff in the\n> >> master, it doesn't seem like we really need to back-patch it.\n> >\n> > Yeah, exactly. I don't see any benefit that's commensurate with\n> > even a small risk of breaking extensions --- and apparently, in\n> > this case that's not a risk but a certainty.\n>\n> +1.\n>\n\nI agree with the points raised here and will revert this for v14.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Tue, 26 Oct 2021 07:50:06 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On 26.10.21 04:20, Amit Kapila wrote:\n> I agree with the points raised here and will revert this for v14.\n\nThanks, Amit. I appreciate the revert.\n\nNote that the removed events were almost at the end of WaitEventIO enum, \nexcept for one last entry: WAIT_EVENT_WAL_WRITE.\n\nJust as a data point: Our BDR extension indeed references the wait \nevents in question (or at least it used to do so up until that commit).\n\n-- \nMarkus Wanner\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 26 Oct 2021 16:02:22 +0200","msg_from":"Markus Wanner <markus.wanner@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."},{"msg_contents":"On Tue, Oct 26, 2021 at 7:34 PM Markus Wanner\n<markus.wanner@enterprisedb.com> wrote:\n>\n> On 26.10.21 04:20, Amit Kapila wrote:\n> > I agree with the points raised here and will revert this for v14.\n>\n> Thanks, Amit. I appreciate the revert.\n>\n> Note that the removed events were almost at the end of WaitEventIO enum,\n> except for one last entry: WAIT_EVENT_WAL_WRITE.\n>\n> Just as a data point: Our BDR extension indeed references the wait\n> events in question (or at least it used to do so up until that commit).\n>\n\nThanks for the relevant information.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Wed, 27 Oct 2021 07:30:20 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Remove unused wait events."}],"string":"[\n {\n \"msg_contents\": \"Remove unused wait events.\\n\\nCommit 464824323e introduced the wait events which were neither used by\\nthat commit nor by follow-up commits for that work.\\n\\nAuthor: Masahiro Ikeda\\nBackpatch-through: 14, where it was introduced\\nDiscussion: https://postgr.es/m/ff077840-3ab2-04dd-bbe4-4f5dfd2ad481@oss.nttdata.com\\n\\nBranch\\n------\\nREL_14_STABLE\\n\\nDetails\\n-------\\nhttps://git.postgresql.org/pg/commitdiff/671eb8f34404d24c8f16ae40e94becb38afd93bb\\n\\nModified Files\\n--------------\\ndoc/src/sgml/monitoring.sgml | 16 ----------------\\nsrc/backend/utils/activity/wait_event.c | 12 ------------\\nsrc/include/utils/wait_event.h | 6 +-----\\n3 files changed, 1 insertion(+), 33 deletions(-)\",\n \"msg_date\": \"Thu, 21 Oct 2021 02:52:04 +0000\",\n \"msg_from\": \"Amit Kapila <akapila@postgresql.org>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 20, 2021 at 10:52 PM Amit Kapila <akapila@postgresql.org> wrote:\\n> Remove unused wait events.\\n>\\n> Commit 464824323e introduced the wait events which were neither used by\\n> that commit nor by follow-up commits for that work.\\n\\nThis commit forces a recompile of every extension that knows about the\\ninteger values assigned to the enums in WaitEventIO. I know of 2\\nextensions that are affected by this. I think that it should be\\nreverted in v14 and kept only in master.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:17:53 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Wed, Oct 20, 2021 at 10:52 PM Amit Kapila <akapila@postgresql.org> wrote:\\n>> Remove unused wait events.\\n\\n> This commit forces a recompile of every extension that knows about the\\n> integer values assigned to the enums in WaitEventIO. I know of 2\\n> extensions that are affected by this. I think that it should be\\n> reverted in v14 and kept only in master.\\n\\nUm ... the removed symbols were at the end of the WaitEventIO enum,\\nso is there really an ABI break? I suppose if an extension contains\\nactual references to the removed symbols, it would fail to recompile,\\nwhich'd be annoying for a released branch.\\n\\nOn the whole, I agree that this patch had no business being committed\\nto v14.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:38:38 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 12:38 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Um ... the removed symbols were at the end of the WaitEventIO enum,\\n> so is there really an ABI break? I suppose if an extension contains\\n> actual references to the removed symbols, it would fail to recompile,\\n> which'd be annoying for a released branch.\\n\\nI think that you're right. I believe one of the two extensions I know\\nabout hopes that values won't be renumbered or become invalid across\\nminor releases, and the other contains specific references to these\\nparticular constants.\\n\\nNow of course it is always arguable whether or not anything that some\\nextension is doing ought to be deemed an acceptable use of the\\nfacilities provided by core, and how much stability ought to be\\nguaranteed. But while I agree it's good to remove unused stuff in the\\nmaster, it doesn't seem like we really need to back-patch it.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:10:25 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> ... But while I agree it's good to remove unused stuff in the\\n> master, it doesn't seem like we really need to back-patch it.\\n\\nYeah, exactly. I don't see any benefit that's commensurate with\\neven a small risk of breaking extensions --- and apparently, in\\nthis case that's not a risk but a certainty.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:18:26 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"> On 25 Oct 2021, at 19:18, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> \\n> Robert Haas <robertmhaas@gmail.com> writes:\\n>> ... But while I agree it's good to remove unused stuff in the\\n>> master, it doesn't seem like we really need to back-patch it.\\n> \\n> Yeah, exactly. I don't see any benefit that's commensurate with\\n> even a small risk of breaking extensions --- and apparently, in\\n> this case that's not a risk but a certainty.\\n\\nSince this will cause integer values to have different textual enum value\\nrepresentations in 14 and 15+, do we want to skip two numbers by assigning the\\nnext wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\\nOr enum integer reuse not something we guarantee against across major versions?\\n\\n--\\nDaniel Gustafsson\\t\\thttps://vmware.com/\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 19:34:37 +0200\",\n \"msg_from\": \"Daniel Gustafsson <daniel@yesql.se>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"Daniel Gustafsson <daniel@yesql.se> writes:\\n> Since this will cause integer values to have different textual enum value\\n> representations in 14 and 15+, do we want to skip two numbers by assigning the\\n> next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\\n> Or enum integer reuse not something we guarantee against across major versions?\\n\\nWe require a recompile across major versions. I don't see a reason why\\nthis particular enum needs more stability than any other one.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:39:44 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On 2021-10-25 13:39:44 -0400, Tom Lane wrote:\\n> Daniel Gustafsson <daniel@yesql.se> writes:\\n> > Since this will cause integer values to have different textual enum value\\n> > representations in 14 and 15+, do we want to skip two numbers by assigning the\\n> > next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\\n> > Or enum integer reuse not something we guarantee against across major versions?\\n> \\n> We require a recompile across major versions. I don't see a reason why\\n> this particular enum needs more stability than any other one.\\n\\n+1. That'd end up pushing us to be more conservative about defining new wait\\nevents, which I think would be bad tradeoff.\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:01:22 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"> On 25 Oct 2021, at 20:01, Andres Freund <andres@anarazel.de> wrote:\\n> \\n> On 2021-10-25 13:39:44 -0400, Tom Lane wrote:\\n>> Daniel Gustafsson <daniel@yesql.se> writes:\\n>>> Since this will cause integer values to have different textual enum value\\n>>> representations in 14 and 15+, do we want to skip two numbers by assigning the\\n>>> next wait event the integer value of WAIT_EVENT_WAL_WRITE incremented by three?\\n>>> Or enum integer reuse not something we guarantee against across major versions?\\n>> \\n>> We require a recompile across major versions. I don't see a reason why\\n>> this particular enum needs more stability than any other one.\\n> \\n> +1. That'd end up pushing us to be more conservative about defining new wait\\n> events, which I think would be bad tradeoff.\\n\\nFair enough, makes sense.\\n\\n--\\nDaniel Gustafsson\\t\\thttps://vmware.com/\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 20:03:54 +0200\",\n \"msg_from\": \"Daniel Gustafsson <daniel@yesql.se>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 01:18:26PM -0400, Tom Lane wrote:\\n> Robert Haas <robertmhaas@gmail.com> writes:\\n>> ... But while I agree it's good to remove unused stuff in the\\n>> master, it doesn't seem like we really need to back-patch it.\\n> \\n> Yeah, exactly. I don't see any benefit that's commensurate with\\n> even a small risk of breaking extensions --- and apparently, in\\n> this case that's not a risk but a certainty.\\n\\n+1.\\n--\\nMichael\",\n \"msg_date\": \"Tue, 26 Oct 2021 10:19:53 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 6:50 AM Michael Paquier <michael@paquier.xyz> wrote:\\n>\\n> On Mon, Oct 25, 2021 at 01:18:26PM -0400, Tom Lane wrote:\\n> > Robert Haas <robertmhaas@gmail.com> writes:\\n> >> ... But while I agree it's good to remove unused stuff in the\\n> >> master, it doesn't seem like we really need to back-patch it.\\n> >\\n> > Yeah, exactly. I don't see any benefit that's commensurate with\\n> > even a small risk of breaking extensions --- and apparently, in\\n> > this case that's not a risk but a certainty.\\n>\\n> +1.\\n>\\n\\nI agree with the points raised here and will revert this for v14.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 07:50:06 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On 26.10.21 04:20, Amit Kapila wrote:\\n> I agree with the points raised here and will revert this for v14.\\n\\nThanks, Amit. I appreciate the revert.\\n\\nNote that the removed events were almost at the end of WaitEventIO enum, \\nexcept for one last entry: WAIT_EVENT_WAL_WRITE.\\n\\nJust as a data point: Our BDR extension indeed references the wait \\nevents in question (or at least it used to do so up until that commit).\\n\\n-- \\nMarkus Wanner\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 16:02:22 +0200\",\n \"msg_from\": \"Markus Wanner <markus.wanner@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 7:34 PM Markus Wanner\\n<markus.wanner@enterprisedb.com> wrote:\\n>\\n> On 26.10.21 04:20, Amit Kapila wrote:\\n> > I agree with the points raised here and will revert this for v14.\\n>\\n> Thanks, Amit. I appreciate the revert.\\n>\\n> Note that the removed events were almost at the end of WaitEventIO enum,\\n> except for one last entry: WAIT_EVENT_WAL_WRITE.\\n>\\n> Just as a data point: Our BDR extension indeed references the wait\\n> events in question (or at least it used to do so up until that commit).\\n>\\n\\nThanks for the relevant information.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 07:30:20 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Remove unused wait events.\"\n }\n]","isConversational":false}}},{"rowIdx":52977,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\n\nI'd like to propose to add new wait event reported while archiver process\nis executing archive_command. This would be helpful to observe\nwhat archiver is doing and check whether it has some troubles or not.\nThought? PoC patch attached.\n\nAlso how about adding wait events for other commands like\narchive_cleanup_command, restore_command and recovery_end_command?\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION","msg_date":"Thu, 21 Oct 2021 22:57:50 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"wait event and archive_command"},{"msg_contents":"On Thu, Oct 21, 2021 at 7:28 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n>\n> Hi,\n>\n> I'd like to propose to add new wait event reported while archiver process\n> is executing archive_command. This would be helpful to observe\n> what archiver is doing and check whether it has some troubles or not.\n> Thought? PoC patch attached.\n>\n> Also how about adding wait events for other commands like\n> archive_cleanup_command, restore_command and recovery_end_command?\n\n+1 for the wait event.\n\nThe following activitymsg that are being set to ps display in\nXLogFileRead and pgarch_archiveXlog have come up for one of our\ninternal team discussions recently:\n\n snprintf(activitymsg, sizeof(activitymsg), \"waiting for %s\",\n xlogfname);\n set_ps_display(activitymsg);\n\n snprintf(activitymsg, sizeof(activitymsg), \"recovering %s\",\n xlogfname);\n set_ps_display(activitymsg);\n\n snprintf(activitymsg, sizeof(activitymsg), \"archiving %s\", xlog);\n set_ps_display(activitymsg);\n\nThe ps display info might be useful if we run postgres on a stand\nalone box and there's someone monitoring at the ps output, but it\ndoesn't help debugging after an issue has occurred. How about we have\nthe following statements which will be useful for someone to look at\nthe server logs and know what was/is happening during the recovery and\narchiving. IMO, we should also have the elog statement.\n\nelog(LOG, \"waiting for %s\", xlogfname);\nelog(LOG, \"recovering %s\"\", xlogfname);\nelog(LOG, \"archiving %s\", xlog);\n\nAnother idea could be to have a hook emitting the above info to\noutside components, but a hook just for this purpose isn't a great\nidea IMO.\n\nThoughts?\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Thu, 21 Oct 2021 20:25:06 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Thu, Oct 21, 2021 at 10:57:50PM +0900, Fujii Masao wrote:\n> Also how about adding wait events for other commands like\n> archive_cleanup_command, restore_command and recovery_end_command?\n\n+1 to add something for all of them as we track the startup process in\npg_stat_activity. Thinking with a larger picture, this comes down to\nthe usage of system(). We could introduce a small wrapper of system()\nthat takes as argument a wait event for the backend.\n--\nMichael","msg_date":"Fri, 22 Oct 2021 18:32:23 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On 2021/10/21 23:55, Bharath Rupireddy wrote:\n>> Also how about adding wait events for other commands like\n>> archive_cleanup_command, restore_command and recovery_end_command?\n> \n> +1 for the wait event.\n\nThanks!\nI added the wait events for also restore_command, etc into the patch.\nI attached that updated version of the patch.\n\n\n> The following activitymsg that are being set to ps display in\n> XLogFileRead and pgarch_archiveXlog have come up for one of our\n> internal team discussions recently:\n> \n> snprintf(activitymsg, sizeof(activitymsg), \"waiting for %s\",\n> xlogfname);\n> set_ps_display(activitymsg);\n> \n> snprintf(activitymsg, sizeof(activitymsg), \"recovering %s\",\n> xlogfname);\n> set_ps_display(activitymsg);\n> \n> snprintf(activitymsg, sizeof(activitymsg), \"archiving %s\", xlog);\n> set_ps_display(activitymsg);\n> \n> The ps display info might be useful if we run postgres on a stand\n> alone box and there's someone monitoring at the ps output, but it\n> doesn't help debugging after an issue has occurred. How about we have\n> the following statements which will be useful for someone to look at\n> the server logs and know what was/is happening during the recovery and\n> archiving.\n\nIf an issue occurs while the command is executing,\nthe error message is logged, isn't it? Isn't that enough for your case?\n\n\n> IMO, we should also have the elog statement.\n> \n> elog(LOG, \"waiting for %s\", xlogfname);\n> elog(LOG, \"recovering %s\"\", xlogfname);\n> elog(LOG, \"archiving %s\", xlog);\n\nI'm afraid that some people think that it's noisy to always log those messages.\n\n\n> Another idea could be to have a hook emitting the above info to\n> outside components, but a hook just for this purpose isn't a great\n> idea IMO.\n\nYes, this idea sounds overkill to me.\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION","msg_date":"Mon, 1 Nov 2021 18:01:13 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"\n\nOn 2021/10/22 18:32, Michael Paquier wrote:\n> On Thu, Oct 21, 2021 at 10:57:50PM +0900, Fujii Masao wrote:\n>> Also how about adding wait events for other commands like\n>> archive_cleanup_command, restore_command and recovery_end_command?\n> \n> +1 to add something for all of them as we track the startup process in\n> pg_stat_activity. Thinking with a larger picture, this comes down to\n> the usage of system(). We could introduce a small wrapper of system()\n> that takes as argument a wait event for the backend.\n\nThat's an idea, but as far as I implemented the patch, introduing such wrapper\nfunction doesn't seem to simplify or improve the source code.\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION\n\n\n","msg_date":"Mon, 1 Nov 2021 18:04:22 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n> On 2021/10/21 23:55, Bharath Rupireddy wrote:\n> >> Also how about adding wait events for other commands like\n> >> archive_cleanup_command, restore_command and recovery_end_command?\n> >\n> > +1 for the wait event.\n>\n> Thanks!\n> I added the wait events for also restore_command, etc into the patch.\n> I attached that updated version of the patch.\n\nThanks for the patch. It looks good to me other than the following comment:\n\n1) Can't we determine the wait event type based on commandName in\nExecuteRecoveryCommand instead of passing it as an extra param?\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Wed, 10 Nov 2021 16:49:54 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"Great, so great. Thanks you\n\nBharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> schrieb am Mi.,\n10. Nov. 2021, 12:20:\n\n> On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com>\n> wrote:\n> > On 2021/10/21 23:55, Bharath Rupireddy wrote:\n> > >> Also how about adding wait events for other commands like\n> > >> archive_cleanup_command, restore_command and recovery_end_command?\n> > >\n> > > +1 for the wait event.\n> >\n> > Thanks!\n> > I added the wait events for also restore_command, etc into the patch.\n> > I attached that updated version of the patch.\n>\n> Thanks for the patch. It looks good to me other than the following comment:\n>\n> 1) Can't we determine the wait event type based on commandName in\n> ExecuteRecoveryCommand instead of passing it as an extra param?\n>\n> Regards,\n> Bharath Rupireddy.\n>\n>\n>\n\nGreat, so great. Thanks youBharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> schrieb am Mi., 10. Nov. 2021, 12:20:On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n> On 2021/10/21 23:55, Bharath Rupireddy wrote:\n> >> Also how about adding wait events for other commands like\n> >> archive_cleanup_command, restore_command and recovery_end_command?\n> >\n> > +1 for the wait event.\n>\n> Thanks!\n> I added the wait events for also restore_command, etc into the patch.\n> I attached that updated version of the patch.\n\nThanks for the patch. It looks good to me other than the following comment:\n\n1) Can't we determine the wait event type based on commandName in\nExecuteRecoveryCommand instead of passing it as an extra param?\n\nRegards,\nBharath Rupireddy.","msg_date":"Wed, 10 Nov 2021 12:25:58 +0100","msg_from":"Sascha Kuhl <yogidabanli@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n> > The following activitymsg that are being set to ps display in\n> > XLogFileRead and pgarch_archiveXlog have come up for one of our\n> > internal team discussions recently:\n> >\n> > snprintf(activitymsg, sizeof(activitymsg), \"waiting for %s\",\n> > xlogfname);\n> > set_ps_display(activitymsg);\n> >\n> > snprintf(activitymsg, sizeof(activitymsg), \"recovering %s\",\n> > xlogfname);\n> > set_ps_display(activitymsg);\n> >\n> > snprintf(activitymsg, sizeof(activitymsg), \"archiving %s\", xlog);\n> > set_ps_display(activitymsg);\n> >\n> > The ps display info might be useful if we run postgres on a stand\n> > alone box and there's someone monitoring at the ps output, but it\n> > doesn't help debugging after an issue has occurred. How about we have\n> > the following statements which will be useful for someone to look at\n> > the server logs and know what was/is happening during the recovery and\n> > archiving.\n>\n> If an issue occurs while the command is executing,\n> the error message is logged, isn't it? Isn't that enough for your case?\n\nYou are right when an issue occurs. However, these messages will be\nuseful 1) if the recovery or archiving is taking a lot of time and one\nwould want to understand how it is progressing. 2) if these commands\npass but an issue occurs in some other area of the code. IMO, we\nshould have these as LOG messages instead of just setting in the ps\ndisplay for temporary purposes which doesn't work well with the\npostgres on cloud where users/admins/developers don't get to see the\nps display.\n\n> > IMO, we should also have the elog statement.\n> >\n> > elog(LOG, \"waiting for %s\", xlogfname);\n> > elog(LOG, \"recovering %s\"\", xlogfname);\n> > elog(LOG, \"archiving %s\", xlog);\n>\n> I'm afraid that some people think that it's noisy to always log those messages.\n\nI don't think these are noisy messages at all. In fact, they will be\nuseful to answer (if not exact answers, but an approximation) some of\nthe customer queries like \"what is happening in my server during the\nrecovery/archiving phase? how much more time recovery might take?\".\nToday, the server emits lot of LOGs, adding these will not blow up the\nserver logs at all if the log rotation policy is configured\nappropriately.\n\nHaving said the above, I plan to discuss these things in a separate thread.\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Wed, 10 Nov 2021 17:00:20 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Wed, Nov 10, 2021 at 5:00 PM Bharath Rupireddy\n<bharath.rupireddyforpostgres@gmail.com> wrote:\n>\n> On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n> > > The following activitymsg that are being set to ps display in\n> > > XLogFileRead and pgarch_archiveXlog have come up for one of our\n> > > internal team discussions recently:\n> > >\n> > > snprintf(activitymsg, sizeof(activitymsg), \"waiting for %s\",\n> > > xlogfname);\n> > > set_ps_display(activitymsg);\n> > >\n> > > snprintf(activitymsg, sizeof(activitymsg), \"recovering %s\",\n> > > xlogfname);\n> > > set_ps_display(activitymsg);\n> > >\n> > > snprintf(activitymsg, sizeof(activitymsg), \"archiving %s\", xlog);\n> > > set_ps_display(activitymsg);\n> > >\n> > > The ps display info might be useful if we run postgres on a stand\n> > > alone box and there's someone monitoring at the ps output, but it\n> > > doesn't help debugging after an issue has occurred. How about we have\n> > > the following statements which will be useful for someone to look at\n> > > the server logs and know what was/is happening during the recovery and\n> > > archiving.\n> >\n> > If an issue occurs while the command is executing,\n> > the error message is logged, isn't it? Isn't that enough for your case?\n>\n> You are right when an issue occurs. However, these messages will be\n> useful 1) if the recovery or archiving is taking a lot of time and one\n> would want to understand how it is progressing. 2) if these commands\n> pass but an issue occurs in some other area of the code. IMO, we\n> should have these as LOG messages instead of just setting in the ps\n> display for temporary purposes which doesn't work well with the\n> postgres on cloud where users/admins/developers don't get to see the\n> ps display.\n>\n> > > IMO, we should also have the elog statement.\n> > >\n> > > elog(LOG, \"waiting for %s\", xlogfname);\n> > > elog(LOG, \"recovering %s\"\", xlogfname);\n> > > elog(LOG, \"archiving %s\", xlog);\n> >\n> > I'm afraid that some people think that it's noisy to always log those messages.\n>\n> I don't think these are noisy messages at all. In fact, they will be\n> useful to answer (if not exact answers, but an approximation) some of\n> the customer queries like \"what is happening in my server during the\n> recovery/archiving phase? how much more time recovery might take?\".\n> Today, the server emits lot of LOGs, adding these will not blow up the\n> server logs at all if the log rotation policy is configured\n> appropriately.\n>\n> Having said the above, I plan to discuss these things in a separate thread.\n\nJust for the records - I've started a new thread for the above\ndiscussion - https://www.postgresql.org/message-id/CALj2ACUfMU%3Dahxivfy%2BZmpVZccd5PASG-_10mLpM55_Y_h4-VA%40mail.gmail.com\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Wed, 10 Nov 2021 23:10:00 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"\n\nOn 2021/11/10 20:19, Bharath Rupireddy wrote:\n> Thanks for the patch. It looks good to me other than the following comment:\n\nThanks for the review!\n\n\n> 1) Can't we determine the wait event type based on commandName in\n> ExecuteRecoveryCommand instead of passing it as an extra param?\n\nYes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\nthe map of command name and wait event? So I feel inclined to avoid adding\nsomething like the following code into the function... Thought?\n\nif (strcmp(commandName, \"recovery_end_command\") == 0)\n wait_event_info = WAIT_EVENT_RECOVERY_END_COMMAND;\nelse if (strcmp(commandName, \"archive_command_command\") == 0)\n...\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION\n\n\n","msg_date":"Thu, 18 Nov 2021 11:23:17 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Thu, Nov 18, 2021 at 11:23:17AM +0900, Fujii Masao wrote:\n> Yes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\n> the map of command name and wait event? So I feel inclined to avoid adding\n> something like the following code into the function... Thought?\n\nFWIW, I find cleaner, and less bug-prone, the approach taken by\nFujii-san's patch to have the wait event set as an argument of the\nfunction rather than trying to guess it from the command data.\n--\nMichael","msg_date":"Thu, 18 Nov 2021 12:43:21 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Thu, Nov 18, 2021 at 7:53 AM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\n> > 1) Can't we determine the wait event type based on commandName in\n> > ExecuteRecoveryCommand instead of passing it as an extra param?\n>\n> Yes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\n> the map of command name and wait event? So I feel inclined to avoid adding\n> something like the following code into the function... Thought?\n>\n> if (strcmp(commandName, \"recovery_end_command\") == 0)\n> wait_event_info = WAIT_EVENT_RECOVERY_END_COMMAND;\n> else if (strcmp(commandName, \"archive_command_command\") == 0)\n\nYeah let's not do that. I'm fine with the\nwait_event_for_archive_command_v2.patch as is.\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Thu, 18 Nov 2021 10:04:57 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\n> Yeah let's not do that. I'm fine with the\n> wait_event_for_archive_command_v2.patch as is.\n\nSwitched the patch as RfC, then.\n--\nMichael","msg_date":"Fri, 19 Nov 2021 16:54:52 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"\n\nOn 2021/11/19 16:54, Michael Paquier wrote:\n> On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\n>> Yeah let's not do that. I'm fine with the\n>> wait_event_for_archive_command_v2.patch as is.\n> \n> Switched the patch as RfC, then.\n\nThanks! Barring any objection, I will commit the patch.\n\nRegards,\n\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION\n\n\n","msg_date":"Sat, 20 Nov 2021 00:19:02 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"Re: wait event and archive_command"},{"msg_contents":"\n\nOn 2021/11/20 0:19, Fujii Masao wrote:\n> \n> \n> On 2021/11/19 16:54, Michael Paquier wrote:\n>> On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\n>>> Yeah let's not do that. I'm fine with the\n>>> wait_event_for_archive_command_v2.patch as is.\n>>\n>> Switched the patch as RfC, then.\n> \n> Thanks! Barring any objection, I will commit the patch.\n\nPushed. Thanks!\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION\n\n\n","msg_date":"Mon, 22 Nov 2021 10:31:57 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":true,"msg_subject":"Re: wait event and archive_command"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\n\\nI'd like to propose to add new wait event reported while archiver process\\nis executing archive_command. This would be helpful to observe\\nwhat archiver is doing and check whether it has some troubles or not.\\nThought? PoC patch attached.\\n\\nAlso how about adding wait events for other commands like\\narchive_cleanup_command, restore_command and recovery_end_command?\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\",\n \"msg_date\": \"Thu, 21 Oct 2021 22:57:50 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 21, 2021 at 7:28 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n>\\n> Hi,\\n>\\n> I'd like to propose to add new wait event reported while archiver process\\n> is executing archive_command. This would be helpful to observe\\n> what archiver is doing and check whether it has some troubles or not.\\n> Thought? PoC patch attached.\\n>\\n> Also how about adding wait events for other commands like\\n> archive_cleanup_command, restore_command and recovery_end_command?\\n\\n+1 for the wait event.\\n\\nThe following activitymsg that are being set to ps display in\\nXLogFileRead and pgarch_archiveXlog have come up for one of our\\ninternal team discussions recently:\\n\\n snprintf(activitymsg, sizeof(activitymsg), \\\"waiting for %s\\\",\\n xlogfname);\\n set_ps_display(activitymsg);\\n\\n snprintf(activitymsg, sizeof(activitymsg), \\\"recovering %s\\\",\\n xlogfname);\\n set_ps_display(activitymsg);\\n\\n snprintf(activitymsg, sizeof(activitymsg), \\\"archiving %s\\\", xlog);\\n set_ps_display(activitymsg);\\n\\nThe ps display info might be useful if we run postgres on a stand\\nalone box and there's someone monitoring at the ps output, but it\\ndoesn't help debugging after an issue has occurred. How about we have\\nthe following statements which will be useful for someone to look at\\nthe server logs and know what was/is happening during the recovery and\\narchiving. IMO, we should also have the elog statement.\\n\\nelog(LOG, \\\"waiting for %s\\\", xlogfname);\\nelog(LOG, \\\"recovering %s\\\"\\\", xlogfname);\\nelog(LOG, \\\"archiving %s\\\", xlog);\\n\\nAnother idea could be to have a hook emitting the above info to\\noutside components, but a hook just for this purpose isn't a great\\nidea IMO.\\n\\nThoughts?\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 20:25:06 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 21, 2021 at 10:57:50PM +0900, Fujii Masao wrote:\\n> Also how about adding wait events for other commands like\\n> archive_cleanup_command, restore_command and recovery_end_command?\\n\\n+1 to add something for all of them as we track the startup process in\\npg_stat_activity. Thinking with a larger picture, this comes down to\\nthe usage of system(). We could introduce a small wrapper of system()\\nthat takes as argument a wait event for the backend.\\n--\\nMichael\",\n \"msg_date\": \"Fri, 22 Oct 2021 18:32:23 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On 2021/10/21 23:55, Bharath Rupireddy wrote:\\n>> Also how about adding wait events for other commands like\\n>> archive_cleanup_command, restore_command and recovery_end_command?\\n> \\n> +1 for the wait event.\\n\\nThanks!\\nI added the wait events for also restore_command, etc into the patch.\\nI attached that updated version of the patch.\\n\\n\\n> The following activitymsg that are being set to ps display in\\n> XLogFileRead and pgarch_archiveXlog have come up for one of our\\n> internal team discussions recently:\\n> \\n> snprintf(activitymsg, sizeof(activitymsg), \\\"waiting for %s\\\",\\n> xlogfname);\\n> set_ps_display(activitymsg);\\n> \\n> snprintf(activitymsg, sizeof(activitymsg), \\\"recovering %s\\\",\\n> xlogfname);\\n> set_ps_display(activitymsg);\\n> \\n> snprintf(activitymsg, sizeof(activitymsg), \\\"archiving %s\\\", xlog);\\n> set_ps_display(activitymsg);\\n> \\n> The ps display info might be useful if we run postgres on a stand\\n> alone box and there's someone monitoring at the ps output, but it\\n> doesn't help debugging after an issue has occurred. How about we have\\n> the following statements which will be useful for someone to look at\\n> the server logs and know what was/is happening during the recovery and\\n> archiving.\\n\\nIf an issue occurs while the command is executing,\\nthe error message is logged, isn't it? Isn't that enough for your case?\\n\\n\\n> IMO, we should also have the elog statement.\\n> \\n> elog(LOG, \\\"waiting for %s\\\", xlogfname);\\n> elog(LOG, \\\"recovering %s\\\"\\\", xlogfname);\\n> elog(LOG, \\\"archiving %s\\\", xlog);\\n\\nI'm afraid that some people think that it's noisy to always log those messages.\\n\\n\\n> Another idea could be to have a hook emitting the above info to\\n> outside components, but a hook just for this purpose isn't a great\\n> idea IMO.\\n\\nYes, this idea sounds overkill to me.\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\",\n \"msg_date\": \"Mon, 1 Nov 2021 18:01:13 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2021/10/22 18:32, Michael Paquier wrote:\\n> On Thu, Oct 21, 2021 at 10:57:50PM +0900, Fujii Masao wrote:\\n>> Also how about adding wait events for other commands like\\n>> archive_cleanup_command, restore_command and recovery_end_command?\\n> \\n> +1 to add something for all of them as we track the startup process in\\n> pg_stat_activity. Thinking with a larger picture, this comes down to\\n> the usage of system(). We could introduce a small wrapper of system()\\n> that takes as argument a wait event for the backend.\\n\\nThat's an idea, but as far as I implemented the patch, introduing such wrapper\\nfunction doesn't seem to simplify or improve the source code.\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 18:04:22 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n> On 2021/10/21 23:55, Bharath Rupireddy wrote:\\n> >> Also how about adding wait events for other commands like\\n> >> archive_cleanup_command, restore_command and recovery_end_command?\\n> >\\n> > +1 for the wait event.\\n>\\n> Thanks!\\n> I added the wait events for also restore_command, etc into the patch.\\n> I attached that updated version of the patch.\\n\\nThanks for the patch. It looks good to me other than the following comment:\\n\\n1) Can't we determine the wait event type based on commandName in\\nExecuteRecoveryCommand instead of passing it as an extra param?\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Wed, 10 Nov 2021 16:49:54 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"Great, so great. Thanks you\\n\\nBharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> schrieb am Mi.,\\n10. Nov. 2021, 12:20:\\n\\n> On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com>\\n> wrote:\\n> > On 2021/10/21 23:55, Bharath Rupireddy wrote:\\n> > >> Also how about adding wait events for other commands like\\n> > >> archive_cleanup_command, restore_command and recovery_end_command?\\n> > >\\n> > > +1 for the wait event.\\n> >\\n> > Thanks!\\n> > I added the wait events for also restore_command, etc into the patch.\\n> > I attached that updated version of the patch.\\n>\\n> Thanks for the patch. It looks good to me other than the following comment:\\n>\\n> 1) Can't we determine the wait event type based on commandName in\\n> ExecuteRecoveryCommand instead of passing it as an extra param?\\n>\\n> Regards,\\n> Bharath Rupireddy.\\n>\\n>\\n>\\n\\nGreat, so great. Thanks youBharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> schrieb am Mi., 10. Nov. 2021, 12:20:On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n> On 2021/10/21 23:55, Bharath Rupireddy wrote:\\n> >> Also how about adding wait events for other commands like\\n> >> archive_cleanup_command, restore_command and recovery_end_command?\\n> >\\n> > +1 for the wait event.\\n>\\n> Thanks!\\n> I added the wait events for also restore_command, etc into the patch.\\n> I attached that updated version of the patch.\\n\\nThanks for the patch. It looks good to me other than the following comment:\\n\\n1) Can't we determine the wait event type based on commandName in\\nExecuteRecoveryCommand instead of passing it as an extra param?\\n\\nRegards,\\nBharath Rupireddy.\",\n \"msg_date\": \"Wed, 10 Nov 2021 12:25:58 +0100\",\n \"msg_from\": \"Sascha Kuhl <yogidabanli@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n> > The following activitymsg that are being set to ps display in\\n> > XLogFileRead and pgarch_archiveXlog have come up for one of our\\n> > internal team discussions recently:\\n> >\\n> > snprintf(activitymsg, sizeof(activitymsg), \\\"waiting for %s\\\",\\n> > xlogfname);\\n> > set_ps_display(activitymsg);\\n> >\\n> > snprintf(activitymsg, sizeof(activitymsg), \\\"recovering %s\\\",\\n> > xlogfname);\\n> > set_ps_display(activitymsg);\\n> >\\n> > snprintf(activitymsg, sizeof(activitymsg), \\\"archiving %s\\\", xlog);\\n> > set_ps_display(activitymsg);\\n> >\\n> > The ps display info might be useful if we run postgres on a stand\\n> > alone box and there's someone monitoring at the ps output, but it\\n> > doesn't help debugging after an issue has occurred. How about we have\\n> > the following statements which will be useful for someone to look at\\n> > the server logs and know what was/is happening during the recovery and\\n> > archiving.\\n>\\n> If an issue occurs while the command is executing,\\n> the error message is logged, isn't it? Isn't that enough for your case?\\n\\nYou are right when an issue occurs. However, these messages will be\\nuseful 1) if the recovery or archiving is taking a lot of time and one\\nwould want to understand how it is progressing. 2) if these commands\\npass but an issue occurs in some other area of the code. IMO, we\\nshould have these as LOG messages instead of just setting in the ps\\ndisplay for temporary purposes which doesn't work well with the\\npostgres on cloud where users/admins/developers don't get to see the\\nps display.\\n\\n> > IMO, we should also have the elog statement.\\n> >\\n> > elog(LOG, \\\"waiting for %s\\\", xlogfname);\\n> > elog(LOG, \\\"recovering %s\\\"\\\", xlogfname);\\n> > elog(LOG, \\\"archiving %s\\\", xlog);\\n>\\n> I'm afraid that some people think that it's noisy to always log those messages.\\n\\nI don't think these are noisy messages at all. In fact, they will be\\nuseful to answer (if not exact answers, but an approximation) some of\\nthe customer queries like \\\"what is happening in my server during the\\nrecovery/archiving phase? how much more time recovery might take?\\\".\\nToday, the server emits lot of LOGs, adding these will not blow up the\\nserver logs at all if the log rotation policy is configured\\nappropriately.\\n\\nHaving said the above, I plan to discuss these things in a separate thread.\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Wed, 10 Nov 2021 17:00:20 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Wed, Nov 10, 2021 at 5:00 PM Bharath Rupireddy\\n<bharath.rupireddyforpostgres@gmail.com> wrote:\\n>\\n> On Mon, Nov 1, 2021 at 2:31 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n> > > The following activitymsg that are being set to ps display in\\n> > > XLogFileRead and pgarch_archiveXlog have come up for one of our\\n> > > internal team discussions recently:\\n> > >\\n> > > snprintf(activitymsg, sizeof(activitymsg), \\\"waiting for %s\\\",\\n> > > xlogfname);\\n> > > set_ps_display(activitymsg);\\n> > >\\n> > > snprintf(activitymsg, sizeof(activitymsg), \\\"recovering %s\\\",\\n> > > xlogfname);\\n> > > set_ps_display(activitymsg);\\n> > >\\n> > > snprintf(activitymsg, sizeof(activitymsg), \\\"archiving %s\\\", xlog);\\n> > > set_ps_display(activitymsg);\\n> > >\\n> > > The ps display info might be useful if we run postgres on a stand\\n> > > alone box and there's someone monitoring at the ps output, but it\\n> > > doesn't help debugging after an issue has occurred. How about we have\\n> > > the following statements which will be useful for someone to look at\\n> > > the server logs and know what was/is happening during the recovery and\\n> > > archiving.\\n> >\\n> > If an issue occurs while the command is executing,\\n> > the error message is logged, isn't it? Isn't that enough for your case?\\n>\\n> You are right when an issue occurs. However, these messages will be\\n> useful 1) if the recovery or archiving is taking a lot of time and one\\n> would want to understand how it is progressing. 2) if these commands\\n> pass but an issue occurs in some other area of the code. IMO, we\\n> should have these as LOG messages instead of just setting in the ps\\n> display for temporary purposes which doesn't work well with the\\n> postgres on cloud where users/admins/developers don't get to see the\\n> ps display.\\n>\\n> > > IMO, we should also have the elog statement.\\n> > >\\n> > > elog(LOG, \\\"waiting for %s\\\", xlogfname);\\n> > > elog(LOG, \\\"recovering %s\\\"\\\", xlogfname);\\n> > > elog(LOG, \\\"archiving %s\\\", xlog);\\n> >\\n> > I'm afraid that some people think that it's noisy to always log those messages.\\n>\\n> I don't think these are noisy messages at all. In fact, they will be\\n> useful to answer (if not exact answers, but an approximation) some of\\n> the customer queries like \\\"what is happening in my server during the\\n> recovery/archiving phase? how much more time recovery might take?\\\".\\n> Today, the server emits lot of LOGs, adding these will not blow up the\\n> server logs at all if the log rotation policy is configured\\n> appropriately.\\n>\\n> Having said the above, I plan to discuss these things in a separate thread.\\n\\nJust for the records - I've started a new thread for the above\\ndiscussion - https://www.postgresql.org/message-id/CALj2ACUfMU%3Dahxivfy%2BZmpVZccd5PASG-_10mLpM55_Y_h4-VA%40mail.gmail.com\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Wed, 10 Nov 2021 23:10:00 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2021/11/10 20:19, Bharath Rupireddy wrote:\\n> Thanks for the patch. It looks good to me other than the following comment:\\n\\nThanks for the review!\\n\\n\\n> 1) Can't we determine the wait event type based on commandName in\\n> ExecuteRecoveryCommand instead of passing it as an extra param?\\n\\nYes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\\nthe map of command name and wait event? So I feel inclined to avoid adding\\nsomething like the following code into the function... Thought?\\n\\nif (strcmp(commandName, \\\"recovery_end_command\\\") == 0)\\n wait_event_info = WAIT_EVENT_RECOVERY_END_COMMAND;\\nelse if (strcmp(commandName, \\\"archive_command_command\\\") == 0)\\n...\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 11:23:17 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 18, 2021 at 11:23:17AM +0900, Fujii Masao wrote:\\n> Yes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\\n> the map of command name and wait event? So I feel inclined to avoid adding\\n> something like the following code into the function... Thought?\\n\\nFWIW, I find cleaner, and less bug-prone, the approach taken by\\nFujii-san's patch to have the wait event set as an argument of the\\nfunction rather than trying to guess it from the command data.\\n--\\nMichael\",\n \"msg_date\": \"Thu, 18 Nov 2021 12:43:21 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 18, 2021 at 7:53 AM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:\\n> > 1) Can't we determine the wait event type based on commandName in\\n> > ExecuteRecoveryCommand instead of passing it as an extra param?\\n>\\n> Yes, that's possible. But isn't it uglier to make ExecuteRecoveryCommand() have\\n> the map of command name and wait event? So I feel inclined to avoid adding\\n> something like the following code into the function... Thought?\\n>\\n> if (strcmp(commandName, \\\"recovery_end_command\\\") == 0)\\n> wait_event_info = WAIT_EVENT_RECOVERY_END_COMMAND;\\n> else if (strcmp(commandName, \\\"archive_command_command\\\") == 0)\\n\\nYeah let's not do that. I'm fine with the\\nwait_event_for_archive_command_v2.patch as is.\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Nov 2021 10:04:57 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\\n> Yeah let's not do that. I'm fine with the\\n> wait_event_for_archive_command_v2.patch as is.\\n\\nSwitched the patch as RfC, then.\\n--\\nMichael\",\n \"msg_date\": \"Fri, 19 Nov 2021 16:54:52 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2021/11/19 16:54, Michael Paquier wrote:\\n> On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\\n>> Yeah let's not do that. I'm fine with the\\n>> wait_event_for_archive_command_v2.patch as is.\\n> \\n> Switched the patch as RfC, then.\\n\\nThanks! Barring any objection, I will commit the patch.\\n\\nRegards,\\n\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Sat, 20 Nov 2021 00:19:02 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: wait event and archive_command\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2021/11/20 0:19, Fujii Masao wrote:\\n> \\n> \\n> On 2021/11/19 16:54, Michael Paquier wrote:\\n>> On Thu, Nov 18, 2021 at 10:04:57AM +0530, Bharath Rupireddy wrote:\\n>>> Yeah let's not do that. I'm fine with the\\n>>> wait_event_for_archive_command_v2.patch as is.\\n>>\\n>> Switched the patch as RfC, then.\\n> \\n> Thanks! Barring any objection, I will commit the patch.\\n\\nPushed. Thanks!\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Nov 2021 10:31:57 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: wait event and archive_command\"\n }\n]","isConversational":false}}},{"rowIdx":52978,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"One problem I've seen in multiple databases and is when a table has a\nmixture of data sets within it. E.g. A queue table where 99% of the\nentries are \"done\" but most queries are working with the 1% that are\n\"new\" or in other states. Often the statistics are skewed by the\n\"done\" entries and give bad estimates for query planning when the\nquery is actually looking at the other rows.\n\nWe've always talked about this as a \"skewed distribution\" or\n\"intercolumn correlation\" problem. And we've developed some tools for\ndealing with those issues. But I've been thinking that's not the only\nproblem with these cases.\n\nThe problem I'm finding is that the distribution of these small\nsubsets can swing quickly. And understanding intercolumn correlations\neven if we could do it perfectly would be no help at all.\n\nConsider a table with millions of rows that are \"done\" but none that\nare \"pending\". Inserting just a few hundred or thousand new pending\nrows makes any estimates based on the existing statistics entirely\nincorrect. Even if we had perfect statistics capable of making perfect\nestimates they would be entirely wrong once a few inserts of pending\nrows are done.\n\nWorse, this is kind of true for even n_dead_tup, n_mod_since_analyze,\netc are kind of affected by this. It's easy (at least on older\nversions, maybe Peter's work has fixed this for btree) to get severe\nindex bloat because vacuum doesn't run for a long time relative to the\nsize of the busy portion of a table.\n\nI'm imagining to really tackle this we should be doing something like\nnoticing when inserts, updates, deletes are affecting key values that\nare \"rare\" according to the statistics and triggering autovacuum\nANALYZE statements that use indexes to only update the statistics for\nthe relevant key ranges.\n\nObviously this could get complex quickly. Perhaps it should be\nsomething users could declare. Some kind of \"partitioned statistics\"\nwhere you declare a where clause and we generate statistics for the\ntable where that where clause is true. Then we could fairly easily\nalso count things like n_mod_since_analyze for that where clause too.\n\nAnd yes, partitioning the table could be a solution to this in some\ncases. I think there are reasons why it isn't always going to work for\nthese issues though, not least that users will likely have other ways\nthey want to partition the data already.\n\n\n-- \ngreg\n\n\n","msg_date":"Thu, 21 Oct 2021 17:12:38 -0400","msg_from":"Greg Stark <stark@mit.edu>","msg_from_op":true,"msg_subject":"Thinking about ANALYZE stats and autovacuum and large non-uniform\n tables"},{"msg_contents":"On Fri, Oct 22, 2021 at 10:13 AM Greg Stark <stark@mit.edu> wrote:\n> Obviously this could get complex quickly. Perhaps it should be\n> something users could declare. Some kind of \"partitioned statistics\"\n> where you declare a where clause and we generate statistics for the\n> table where that where clause is true. Then we could fairly easily\n> also count things like n_mod_since_analyze for that where clause too.\n\nIt's a different thing, but somehow related and maybe worth\nmentioning, that in DB2 you can declare a table to be VOLATILE. In\nthat case, by some unspecified different heuristics, it'll prefer\nindex scans over table scans, and it's intended to give stable\nperformance for queue-like tables by defending against automatically\nscheduled stats being collected at a bad time. It's been a while\nsince I ran busy queue-like workloads on DB2 but I seem to recall it\nwas more about the dangers of tables that sometimes have say 10 rows\nand something 42 million, rather than the case of 42 million DONE rows\nand 0-10 PENDING rows, but not a million miles off.\n\n\n","msg_date":"Fri, 22 Oct 2021 10:42:23 +1300","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":false,"msg_subject":"Re: Thinking about ANALYZE stats and autovacuum and large non-uniform\n tables"},{"msg_contents":"On Thu, Oct 21, 2021 at 2:13 PM Greg Stark <stark@mit.edu> wrote:\n> The problem I'm finding is that the distribution of these small\n> subsets can swing quickly. And understanding intercolumn correlations\n> even if we could do it perfectly would be no help at all.\n>\n> Consider a table with millions of rows that are \"done\" but none that\n> are \"pending\". Inserting just a few hundred or thousand new pending\n> rows makes any estimates based on the existing statistics entirely\n> incorrect. Even if we had perfect statistics capable of making perfect\n> estimates they would be entirely wrong once a few inserts of pending\n> rows are done.\n\nI am very sympathetic to this view of things. Because this asymmetry\nobviously exists, and matters. There is no getting around that.\n\n> Worse, this is kind of true for even n_dead_tup, n_mod_since_analyze,\n> etc are kind of affected by this. It's easy (at least on older\n> versions, maybe Peter's work has fixed this for btree) to get severe\n> index bloat because vacuum doesn't run for a long time relative to the\n> size of the busy portion of a table.\n\nMy work (especially in 14) has definitely helped a great deal with\nindex bloat, by cleaning it up in a targeted fashion, based on\npage-level considerations. This is just the only thing that can work;\nwe can never expect VACUUM to be able to deal with that, no matter\nwhat. Simply because it's totally normal and expected for index bloat\nto grow at an uneven rate over time.\n\nI do still think that there is an unsolved issue here, which leads to\nproblems with index bloat when there isn't \"B-Tree keyspace\nconcentration\" of garbage index tuples. That problem is with the\nstatistics that drive VACUUM themselves; they just don't work very\nwell in certain cases [1]. Statistics that drive autovacuum usually\ncome from ANALYZE, of course. The entire intellectual justification\nfor database statistics doesn't really carry over to VACUUM. There are\ncertain \"physical database\" implementation details that bleed into the\nway ANALYZE counts dead rows. For example, most dead tuples are\nusually LP_DEAD stub line pointers (not even tuples). They're only 4\nbytes, whereas live tuples are about 30 bytes at a minimum (depending\non how you count it). This leads to the ANALYZE block-based sampling\nbecoming confused.\n\nThis confusion seems related to the fact that ANALYZE is really a\n\"logical database\" thing. It's slightly amazing that statistics from\nANALYZE work as well as they do for query planning, so we shouldn't be\ntoo surprised.\n\nNote that the TPC-C issue I describe in [1] involves a table that's a\nlittle bit like a queue table, but with lots of non-HOT updates (lots\noverall, but only one update per logical row, ever). This might tie\nthings to what Thomas just said about DB2 and queue tables.\n\n> I'm imagining to really tackle this we should be doing something like\n> noticing when inserts, updates, deletes are affecting key values that\n> are \"rare\" according to the statistics and triggering autovacuum\n> ANALYZE statements that use indexes to only update the statistics for\n> the relevant key ranges.\n\nI'm not sure. I tend to think that the most promising approaches all\ninvolve some kind of execution time smarts about the statistics, and\ntheir inherent unreliability. Somehow query execution itself should\nbecome less gullible, at least in cases where we really can have high\nconfidence in the statistics being wrong at this exact time, for this\nexact key space.\n\n[1] https://postgr.es/m/CAH2-Wz=9R83wcwZcPUH4FVPeDM4znzbzMvp3rt21+XhQWMU8+g@mail.gmail.com\n--\nPeter Geoghegan\n\n\n","msg_date":"Thu, 21 Oct 2021 14:45:36 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":false,"msg_subject":"Re: Thinking about ANALYZE stats and autovacuum and large non-uniform\n tables"}],"string":"[\n {\n \"msg_contents\": \"One problem I've seen in multiple databases and is when a table has a\\nmixture of data sets within it. E.g. A queue table where 99% of the\\nentries are \\\"done\\\" but most queries are working with the 1% that are\\n\\\"new\\\" or in other states. Often the statistics are skewed by the\\n\\\"done\\\" entries and give bad estimates for query planning when the\\nquery is actually looking at the other rows.\\n\\nWe've always talked about this as a \\\"skewed distribution\\\" or\\n\\\"intercolumn correlation\\\" problem. And we've developed some tools for\\ndealing with those issues. But I've been thinking that's not the only\\nproblem with these cases.\\n\\nThe problem I'm finding is that the distribution of these small\\nsubsets can swing quickly. And understanding intercolumn correlations\\neven if we could do it perfectly would be no help at all.\\n\\nConsider a table with millions of rows that are \\\"done\\\" but none that\\nare \\\"pending\\\". Inserting just a few hundred or thousand new pending\\nrows makes any estimates based on the existing statistics entirely\\nincorrect. Even if we had perfect statistics capable of making perfect\\nestimates they would be entirely wrong once a few inserts of pending\\nrows are done.\\n\\nWorse, this is kind of true for even n_dead_tup, n_mod_since_analyze,\\netc are kind of affected by this. It's easy (at least on older\\nversions, maybe Peter's work has fixed this for btree) to get severe\\nindex bloat because vacuum doesn't run for a long time relative to the\\nsize of the busy portion of a table.\\n\\nI'm imagining to really tackle this we should be doing something like\\nnoticing when inserts, updates, deletes are affecting key values that\\nare \\\"rare\\\" according to the statistics and triggering autovacuum\\nANALYZE statements that use indexes to only update the statistics for\\nthe relevant key ranges.\\n\\nObviously this could get complex quickly. Perhaps it should be\\nsomething users could declare. Some kind of \\\"partitioned statistics\\\"\\nwhere you declare a where clause and we generate statistics for the\\ntable where that where clause is true. Then we could fairly easily\\nalso count things like n_mod_since_analyze for that where clause too.\\n\\nAnd yes, partitioning the table could be a solution to this in some\\ncases. I think there are reasons why it isn't always going to work for\\nthese issues though, not least that users will likely have other ways\\nthey want to partition the data already.\\n\\n\\n-- \\ngreg\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 17:12:38 -0400\",\n \"msg_from\": \"Greg Stark <stark@mit.edu>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Thinking about ANALYZE stats and autovacuum and large non-uniform\\n tables\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 10:13 AM Greg Stark <stark@mit.edu> wrote:\\n> Obviously this could get complex quickly. Perhaps it should be\\n> something users could declare. Some kind of \\\"partitioned statistics\\\"\\n> where you declare a where clause and we generate statistics for the\\n> table where that where clause is true. Then we could fairly easily\\n> also count things like n_mod_since_analyze for that where clause too.\\n\\nIt's a different thing, but somehow related and maybe worth\\nmentioning, that in DB2 you can declare a table to be VOLATILE. In\\nthat case, by some unspecified different heuristics, it'll prefer\\nindex scans over table scans, and it's intended to give stable\\nperformance for queue-like tables by defending against automatically\\nscheduled stats being collected at a bad time. It's been a while\\nsince I ran busy queue-like workloads on DB2 but I seem to recall it\\nwas more about the dangers of tables that sometimes have say 10 rows\\nand something 42 million, rather than the case of 42 million DONE rows\\nand 0-10 PENDING rows, but not a million miles off.\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 10:42:23 +1300\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Thinking about ANALYZE stats and autovacuum and large non-uniform\\n tables\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 21, 2021 at 2:13 PM Greg Stark <stark@mit.edu> wrote:\\n> The problem I'm finding is that the distribution of these small\\n> subsets can swing quickly. And understanding intercolumn correlations\\n> even if we could do it perfectly would be no help at all.\\n>\\n> Consider a table with millions of rows that are \\\"done\\\" but none that\\n> are \\\"pending\\\". Inserting just a few hundred or thousand new pending\\n> rows makes any estimates based on the existing statistics entirely\\n> incorrect. Even if we had perfect statistics capable of making perfect\\n> estimates they would be entirely wrong once a few inserts of pending\\n> rows are done.\\n\\nI am very sympathetic to this view of things. Because this asymmetry\\nobviously exists, and matters. There is no getting around that.\\n\\n> Worse, this is kind of true for even n_dead_tup, n_mod_since_analyze,\\n> etc are kind of affected by this. It's easy (at least on older\\n> versions, maybe Peter's work has fixed this for btree) to get severe\\n> index bloat because vacuum doesn't run for a long time relative to the\\n> size of the busy portion of a table.\\n\\nMy work (especially in 14) has definitely helped a great deal with\\nindex bloat, by cleaning it up in a targeted fashion, based on\\npage-level considerations. This is just the only thing that can work;\\nwe can never expect VACUUM to be able to deal with that, no matter\\nwhat. Simply because it's totally normal and expected for index bloat\\nto grow at an uneven rate over time.\\n\\nI do still think that there is an unsolved issue here, which leads to\\nproblems with index bloat when there isn't \\\"B-Tree keyspace\\nconcentration\\\" of garbage index tuples. That problem is with the\\nstatistics that drive VACUUM themselves; they just don't work very\\nwell in certain cases [1]. Statistics that drive autovacuum usually\\ncome from ANALYZE, of course. The entire intellectual justification\\nfor database statistics doesn't really carry over to VACUUM. There are\\ncertain \\\"physical database\\\" implementation details that bleed into the\\nway ANALYZE counts dead rows. For example, most dead tuples are\\nusually LP_DEAD stub line pointers (not even tuples). They're only 4\\nbytes, whereas live tuples are about 30 bytes at a minimum (depending\\non how you count it). This leads to the ANALYZE block-based sampling\\nbecoming confused.\\n\\nThis confusion seems related to the fact that ANALYZE is really a\\n\\\"logical database\\\" thing. It's slightly amazing that statistics from\\nANALYZE work as well as they do for query planning, so we shouldn't be\\ntoo surprised.\\n\\nNote that the TPC-C issue I describe in [1] involves a table that's a\\nlittle bit like a queue table, but with lots of non-HOT updates (lots\\noverall, but only one update per logical row, ever). This might tie\\nthings to what Thomas just said about DB2 and queue tables.\\n\\n> I'm imagining to really tackle this we should be doing something like\\n> noticing when inserts, updates, deletes are affecting key values that\\n> are \\\"rare\\\" according to the statistics and triggering autovacuum\\n> ANALYZE statements that use indexes to only update the statistics for\\n> the relevant key ranges.\\n\\nI'm not sure. I tend to think that the most promising approaches all\\ninvolve some kind of execution time smarts about the statistics, and\\ntheir inherent unreliability. Somehow query execution itself should\\nbecome less gullible, at least in cases where we really can have high\\nconfidence in the statistics being wrong at this exact time, for this\\nexact key space.\\n\\n[1] https://postgr.es/m/CAH2-Wz=9R83wcwZcPUH4FVPeDM4znzbzMvp3rt21+XhQWMU8+g@mail.gmail.com\\n--\\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 14:45:36 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Thinking about ANALYZE stats and autovacuum and large non-uniform\\n tables\"\n }\n]","isConversational":false}}},{"rowIdx":52979,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\nw.r.t. 0001-Partial-aggregates-push-down-v03.patch\n\nFor partial_agg_ok(),\n\n+ if (agg->aggdistinct || agg->aggvariadic || agg->aggkind !=\nAGGKIND_NORMAL || agg->aggorder != NIL)\n+ ok = false;\n\nSince SearchSysCache1() is not called yet, you can return false directly.\n\n+ if (aggform->aggpartialpushdownsafe != true)\n\nThe above can be written as:\n\n if (!aggform->aggpartialpushdownsafe)\n\nFor build_conv_list():\n\n+ Oid converter_oid = InvalidOid;\n+\n+ if (IsA(tlentry->expr, Aggref))\n...\n+ }\n+ convlist = lappend_oid(convlist, converter_oid);\n\nDo you intend to append InvalidOid to convlist (when tlentry->expr is\nnot Aggref) ?\n\nCheers\n\nHi,w.r.t. 0001-Partial-aggregates-push-down-v03.patchFor partial_agg_ok(),+ if (agg->aggdistinct || agg->aggvariadic || agg->aggkind != AGGKIND_NORMAL || agg->aggorder != NIL)+ ok = false;Since SearchSysCache1() is not called yet, you can return false directly.+ if (aggform->aggpartialpushdownsafe != true)The above can be written as: if (!aggform->aggpartialpushdownsafe)For build_conv_list():+ Oid converter_oid = InvalidOid;++ if (IsA(tlentry->expr, Aggref))...+ }+ convlist = lappend_oid(convlist, converter_oid);Do you intend to append InvalidOid to convlist (when tlentry->expr is not Aggref) ?Cheers","msg_date":"Thu, 21 Oct 2021 14:43:38 -0700","msg_from":"Zhihong Yu <zyu@yugabyte.com>","msg_from_op":true,"msg_subject":"Re: Partial aggregates pushdown"},{"msg_contents":"Zhihong Yu писал 2021-10-22 00:43:\n> Hi,\n> w.r.t. 0001-Partial-aggregates-push-down-v03.patch\n> \n\nHi.\n\n> For partial_agg_ok(),\n> \n> + if (agg->aggdistinct || agg->aggvariadic || agg->aggkind !=\n> AGGKIND_NORMAL || agg->aggorder != NIL)\n> + ok = false;\n> \n> Since SearchSysCache1() is not called yet, you can return false\n> directly.\n\nFixed.\n\n> \n> + if (aggform->aggpartialpushdownsafe != true)\n> \n> The above can be written as:\n> \n> if (!aggform->aggpartialpushdownsafe)\n\nFixed.\n\n> \n> For build_conv_list():\n> \n> + Oid converter_oid = InvalidOid;\n> +\n> + if (IsA(tlentry->expr, Aggref))\n> \n> ...\n> + }\n> + convlist = lappend_oid(convlist, converter_oid);\n> \n> Do you intend to append InvalidOid to convlist (when tlentry->expr is\n> not Aggref) ?\n\nYes, for each tlist member (which matches fpinfo->grouped_tlist in case \nwhen foreignrel is UPPER_REL) we need to find corresponding converter.\nIf we don't append InvalidOid, we can't find convlist member, \ncorresponding to tlist member. Added comments to build_conv_list.\n\nAlso fixed error in pg_dump.c (we selected '0' when \naggpartialconverterfn was not defined in schema, but checked for '-').\n\n-- \nBest regards,\nAlexander Pyhalov,\nPostgres Professional","msg_date":"Fri, 22 Oct 2021 09:26:50 +0300","msg_from":"Alexander Pyhalov <a.pyhalov@postgrespro.ru>","msg_from_op":false,"msg_subject":"Re: Partial aggregates pushdown"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\nw.r.t. 0001-Partial-aggregates-push-down-v03.patch\\n\\nFor partial_agg_ok(),\\n\\n+ if (agg->aggdistinct || agg->aggvariadic || agg->aggkind !=\\nAGGKIND_NORMAL || agg->aggorder != NIL)\\n+ ok = false;\\n\\nSince SearchSysCache1() is not called yet, you can return false directly.\\n\\n+ if (aggform->aggpartialpushdownsafe != true)\\n\\nThe above can be written as:\\n\\n if (!aggform->aggpartialpushdownsafe)\\n\\nFor build_conv_list():\\n\\n+ Oid converter_oid = InvalidOid;\\n+\\n+ if (IsA(tlentry->expr, Aggref))\\n...\\n+ }\\n+ convlist = lappend_oid(convlist, converter_oid);\\n\\nDo you intend to append InvalidOid to convlist (when tlentry->expr is\\nnot Aggref) ?\\n\\nCheers\\n\\nHi,w.r.t. 0001-Partial-aggregates-push-down-v03.patchFor partial_agg_ok(),+ if (agg->aggdistinct || agg->aggvariadic || agg->aggkind != AGGKIND_NORMAL || agg->aggorder != NIL)+ ok = false;Since SearchSysCache1() is not called yet, you can return false directly.+ if (aggform->aggpartialpushdownsafe != true)The above can be written as: if (!aggform->aggpartialpushdownsafe)For build_conv_list():+ Oid converter_oid = InvalidOid;++ if (IsA(tlentry->expr, Aggref))...+ }+ convlist = lappend_oid(convlist, converter_oid);Do you intend to append InvalidOid to convlist (when tlentry->expr is not Aggref) ?Cheers\",\n \"msg_date\": \"Thu, 21 Oct 2021 14:43:38 -0700\",\n \"msg_from\": \"Zhihong Yu <zyu@yugabyte.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Partial aggregates pushdown\"\n },\n {\n \"msg_contents\": \"Zhihong Yu писал 2021-10-22 00:43:\\n> Hi,\\n> w.r.t. 0001-Partial-aggregates-push-down-v03.patch\\n> \\n\\nHi.\\n\\n> For partial_agg_ok(),\\n> \\n> + if (agg->aggdistinct || agg->aggvariadic || agg->aggkind !=\\n> AGGKIND_NORMAL || agg->aggorder != NIL)\\n> + ok = false;\\n> \\n> Since SearchSysCache1() is not called yet, you can return false\\n> directly.\\n\\nFixed.\\n\\n> \\n> + if (aggform->aggpartialpushdownsafe != true)\\n> \\n> The above can be written as:\\n> \\n> if (!aggform->aggpartialpushdownsafe)\\n\\nFixed.\\n\\n> \\n> For build_conv_list():\\n> \\n> + Oid converter_oid = InvalidOid;\\n> +\\n> + if (IsA(tlentry->expr, Aggref))\\n> \\n> ...\\n> + }\\n> + convlist = lappend_oid(convlist, converter_oid);\\n> \\n> Do you intend to append InvalidOid to convlist (when tlentry->expr is\\n> not Aggref) ?\\n\\nYes, for each tlist member (which matches fpinfo->grouped_tlist in case \\nwhen foreignrel is UPPER_REL) we need to find corresponding converter.\\nIf we don't append InvalidOid, we can't find convlist member, \\ncorresponding to tlist member. Added comments to build_conv_list.\\n\\nAlso fixed error in pg_dump.c (we selected '0' when \\naggpartialconverterfn was not defined in schema, but checked for '-').\\n\\n-- \\nBest regards,\\nAlexander Pyhalov,\\nPostgres Professional\",\n \"msg_date\": \"Fri, 22 Oct 2021 09:26:50 +0300\",\n \"msg_from\": \"Alexander Pyhalov <a.pyhalov@postgrespro.ru>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Partial aggregates pushdown\"\n }\n]","isConversational":false}}},{"rowIdx":52980,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Today, pg_dump does a lot of internal lookups via binary search\nin presorted arrays. I thought it might improve matters\nto replace those binary searches with hash tables, theoretically\nconverting O(log N) searches into O(1) searches. So I tried making\na hash table indexed by CatalogId (tableoid+oid) with simplehash.h,\nand replacing as many data structures as I could with that.\n\nThis makes the code shorter and (IMO anyway) cleaner, but\n\n(a) the executable size increases by a few KB --- apparently, even\nthe minimum subset of simplehash.h's functionality is code-wasteful.\n\n(b) I couldn't measure any change in performance at all. I tried\nit on the regression database and on a toy DB with 10000 simple\ntables. Maybe on a really large DB you'd notice some difference,\nbut I'm not very optimistic now.\n\nSo this experiment feels like a failure, but I thought I'd post\nthe patch and results for the archives' sake. Maybe somebody\nwill think of a way to improve matters. Or maybe it's worth\ndoing just to shorten the code?\n\n\t\t\tregards, tom lane","msg_date":"Thu, 21 Oct 2021 18:27:25 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Experimenting with hash tables inside pg_dump"},{"msg_contents":"On 10/21/21, 3:29 PM, \"Tom Lane\" <tgl@sss.pgh.pa.us> wrote:\r\n> (b) I couldn't measure any change in performance at all. I tried\r\n> it on the regression database and on a toy DB with 10000 simple\r\n> tables. Maybe on a really large DB you'd notice some difference,\r\n> but I'm not very optimistic now.\r\n\r\nI wonder how many tables you'd need to start seeing a difference.\r\nThere are certainly databases out there with many more than 10,000\r\ntables. I'll look into this...\r\n\r\nNathan\r\n\r\n","msg_date":"Thu, 21 Oct 2021 23:13:11 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-21 18:27:25 -0400, Tom Lane wrote:\n> Today, pg_dump does a lot of internal lookups via binary search\n> in presorted arrays. I thought it might improve matters\n> to replace those binary searches with hash tables, theoretically\n> converting O(log N) searches into O(1) searches. So I tried making\n> a hash table indexed by CatalogId (tableoid+oid) with simplehash.h,\n> and replacing as many data structures as I could with that.\n\nThat does sound like a good idea in theory...\n\n\n> This makes the code shorter and (IMO anyway) cleaner, but\n> \n> (a) the executable size increases by a few KB --- apparently, even\n> the minimum subset of simplehash.h's functionality is code-wasteful.\n\nHm. Surprised a bit by that. In an optimized build the difference is a\nsmaller, at least.\n\noptimized:\n text\t data\t bss\t dec\t hex\tfilename\n 448066\t 7048\t 1368\t 456482\t 6f722\tsrc/bin/pg_dump/pg_dump\n 447530\t 7048\t 1496\t 456074\t 6f58a\tsrc/bin/pg_dump/pg_dump.orig\n\ndebug:\n text\t data\t bss\t dec\t hex\tfilename\n 516883\t 7024\t 1352\t 525259\t 803cb\tsrc/bin/pg_dump/pg_dump\n 509819\t 7024\t 1480\t 518323\t 7e8b3\tsrc/bin/pg_dump/pg_dump.orig\n\nThe fact that optimization plays such a role makes me wonder if a good chunk\nof the difference is the slightly more complicated find{Type,Func,...}ByOid()\nfunctions.\n\n\n> (b) I couldn't measure any change in performance at all. I tried\n> it on the regression database and on a toy DB with 10000 simple\n> tables. Maybe on a really large DB you'd notice some difference,\n> but I'm not very optimistic now.\n\nDid you measure runtime of pg_dump, or how much CPU it used? I think a lot of\nthe time the backend is a bigger bottleneck than pg_dump...\n\nFor the regression test DB the majority of the time seems to be spent below\ntwo things:\n1) libpq\n2) sortDumpableObjects().\n\nI don't think 2) hits the binary search / hashtable path?\n\n\nIt does seem interesting that a substantial part of the time is spent in/below\nPQexec() and PQfnumber(). Especially the latter shouldn't be too hard to\noptimize away...\n\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 21 Oct 2021 16:37:57 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"On 10/21/21, 4:14 PM, \"Bossart, Nathan\" <bossartn@amazon.com> wrote:\r\n> On 10/21/21, 3:29 PM, \"Tom Lane\" <tgl@sss.pgh.pa.us> wrote:\r\n>> (b) I couldn't measure any change in performance at all. I tried\r\n>> it on the regression database and on a toy DB with 10000 simple\r\n>> tables. Maybe on a really large DB you'd notice some difference,\r\n>> but I'm not very optimistic now.\r\n>\r\n> I wonder how many tables you'd need to start seeing a difference.\r\n> There are certainly databases out there with many more than 10,000\r\n> tables. I'll look into this...\r\n\r\nWell, I tested with 200,000 tables and saw no difference with this.\r\n\r\nNathan\r\n\r\n","msg_date":"Thu, 21 Oct 2021 23:59:57 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> Did you measure runtime of pg_dump, or how much CPU it used?\n\nI was looking mostly at wall-clock runtime, though I did notice\nthat the CPU time looked about the same too.\n\n> I think a lot of\n> the time the backend is a bigger bottleneck than pg_dump...\n\nYeah, that. I tried doing a system-wide \"perf\" measurement, and soon\nrealized that a big fraction of the time for a \"pg_dump -s\" run is\nbeing spent in the planner :-(. I'm currently experimenting with\nPREPARE'ing pg_dump's repetitive queries, and it's looking very\npromising. More later.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 21 Oct 2021 20:22:56 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-21 16:37:57 -0700, Andres Freund wrote:\n> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\n> > (a) the executable size increases by a few KB --- apparently, even\n> > the minimum subset of simplehash.h's functionality is code-wasteful.\n> \n> Hm. Surprised a bit by that. In an optimized build the difference is a\n> smaller, at least.\n> \n> optimized:\n> text\t data\t bss\t dec\t hex\tfilename\n> 448066\t 7048\t 1368\t 456482\t 6f722\tsrc/bin/pg_dump/pg_dump\n> 447530\t 7048\t 1496\t 456074\t 6f58a\tsrc/bin/pg_dump/pg_dump.orig\n> \n> debug:\n> text\t data\t bss\t dec\t hex\tfilename\n> 516883\t 7024\t 1352\t 525259\t 803cb\tsrc/bin/pg_dump/pg_dump\n> 509819\t 7024\t 1480\t 518323\t 7e8b3\tsrc/bin/pg_dump/pg_dump.orig\n> \n> The fact that optimization plays such a role makes me wonder if a good chunk\n> of the difference is the slightly more complicated find{Type,Func,...}ByOid()\n> functions.\n\nIt's not that.\n\nIn a debug build a good chunk of it is due to a bunch of Assert()s. Another\npart is that trivial helper functions like SH_PREV() don't get inlined.\n\nThe increase for an optimized build seems to boil down to pg_log_error()\ninvocations. If I replace those with an exit(1), the resulting binaries are\nwithin 100 byte.\n\nIf I prevent the compiler from inlining findObjectByCatalogId() in all the\nfind*ByOid() routines, your version is smaller than master even without other\nchanges.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 21 Oct 2021 17:47:15 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-21 20:22:56 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> Yeah, that. I tried doing a system-wide \"perf\" measurement, and soon\n> realized that a big fraction of the time for a \"pg_dump -s\" run is\n> being spent in the planner :-(.\n\nA trick for seeing the proportions of this easily in perf is to start both\npostgres and pg_dump pinned to a specific CPU, and profile that cpu. That gets\nrid of most of the noise of other programs etc.\n\n\n\n> I'm currently experimenting with\n> PREPARE'ing pg_dump's repetitive queries, and it's looking very\n> promising. More later.\n\nGood idea.\n\nI wonder though if for some of them we should instead replace the per-object\nqueries with one query returning the information for all objects of a type. It\ndoesn't make all that much sense that we build and send one query for each\ntable and index.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 21 Oct 2021 18:09:36 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> I wonder though if for some of them we should instead replace the per-object\n> queries with one query returning the information for all objects of a type. It\n> doesn't make all that much sense that we build and send one query for each\n> table and index.\n\nThe trick is the problem I alluded to in another thread: it's not safe to\ndo stuff like pg_get_expr() on tables we don't have lock on.\n\nI've thought about doing something like\n\nSELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\n\nbut in cases with tens of thousands of tables, it seems unlikely that\nthat's going to behave all that nicely.\n\nThe *real* fix, I suppose, would be to fix all those catalog-inspection\nfunctions so that they operate with respect to the query's snapshot.\nBut that's not a job I'm volunteering for. Besides which, pg_dump\nstill has to cope with back-rev servers where it wouldn't be safe.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 21 Oct 2021 22:13:22 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-21 22:13:22 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> > I wonder though if for some of them we should instead replace the per-object\n> > queries with one query returning the information for all objects of a type. It\n> > doesn't make all that much sense that we build and send one query for each\n> > table and index.\n> \n> The trick is the problem I alluded to in another thread: it's not safe to\n> do stuff like pg_get_expr() on tables we don't have lock on.\n\nI was looking at getTableAttrs() - sending one query instead of #tables\nqueries yields a quite substantial speedup in a quick prototype. And I don't\nthink it changes anything around locking semantics.\n\n\n> I've thought about doing something like\n> \n> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\n> \n> but in cases with tens of thousands of tables, it seems unlikely that\n> that's going to behave all that nicely.\n\nThat's kinda what I'm doing in the quick hack. But instead of using IN(...) I\nmade it unnest('{oid, oid, ...}'), that scales much better.\n\nA pg_dump --schema-only of the regression database goes from\n\nreal\t0m0.675s\nuser\t0m0.039s\nsys\t0m0.029s\n\nto\n\nreal\t0m0.477s\nuser\t0m0.037s\nsys\t0m0.020s\n\nwhich isn't half-bad.\n\nThere's a few more cases like this I think. But most are harder because the\ndumping happens one-by-one from dumpDumpableObject(). The relatively easy but\nsubstantial cases I could find quickly were getIndexes(), getConstraints(),\ngetTriggers()\n\n\nTo see where it's worth putting in time it'd be useful if getSchemaData() in\nverbose mode printed timing information...\n\n\n> The *real* fix, I suppose, would be to fix all those catalog-inspection\n> functions so that they operate with respect to the query's snapshot.\n> But that's not a job I'm volunteering for. Besides which, pg_dump\n> still has to cope with back-rev servers where it wouldn't be safe.\n\nYea, that's not a small change :(. I suspect that we'd need a bunch of new\ncaching infrastructure to make that reasonably performant, since this\npresumably couldn't use syscache etc.\n\nGreetings,\n\nAndres Freund","msg_date":"Thu, 21 Oct 2021 22:59:39 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-21 22:13:22 -0400, Tom Lane wrote:\n>> I've thought about doing something like\n>> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\n>> but in cases with tens of thousands of tables, it seems unlikely that\n>> that's going to behave all that nicely.\n\n> That's kinda what I'm doing in the quick hack. But instead of using IN(...) I\n> made it unnest('{oid, oid, ...}'), that scales much better.\n\nI'm skeptical of that, mainly because it doesn't work in old servers,\nand I really don't want to maintain two fundamentally different\nversions of getTableAttrs(). I don't think you actually need the\nmulti-array form of unnest() here --- we know the TableInfo array\nis in OID order --- but even the single-array form only works\nback to 8.4.\n\nHowever ... looking through getTableAttrs' main query, it seems\nlike the only thing there that's potentially unsafe is the\n\"format_type(t.oid, a.atttypmod)\" call. I wonder if it could be\nsane to convert it into a single query that just scans all of\npg_attribute, and then deal with creating the formatted type names\nseparately, perhaps with an improved version of getFormattedTypeName\nthat could cache the results for non-default typmods. The main\nknock on this approach is the temptation for somebody to stick some\nunsafe function into the query in future. We could stick a big fat\nwarning comment into the code, but lately I despair of people reading\ncomments.\n\n> To see where it's worth putting in time it'd be useful if getSchemaData() in\n> verbose mode printed timing information...\n\nI've been running test cases with log_min_duration_statement = 0,\nwhich serves well enough.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 10:53:31 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-22 10:53:31 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> > On 2021-10-21 22:13:22 -0400, Tom Lane wrote:\n> >> I've thought about doing something like\n> >> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\n> >> but in cases with tens of thousands of tables, it seems unlikely that\n> >> that's going to behave all that nicely.\n> \n> > That's kinda what I'm doing in the quick hack. But instead of using IN(...) I\n> > made it unnest('{oid, oid, ...}'), that scales much better.\n> \n> I'm skeptical of that, mainly because it doesn't work in old servers,\n> and I really don't want to maintain two fundamentally different\n> versions of getTableAttrs(). I don't think you actually need the\n> multi-array form of unnest() here --- we know the TableInfo array\n> is in OID order --- but even the single-array form only works\n> back to 8.4.\n\nI think we can address that, if we think it's overall a promising approach to\npursue. E.g. if we don't need the indexes, we can make it = ANY().\n\n\n> However ... looking through getTableAttrs' main query, it seems\n> like the only thing there that's potentially unsafe is the\n> \"format_type(t.oid, a.atttypmod)\" call.\n\nI assume the default expression bit would also be unsafe?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Fri, 22 Oct 2021 08:21:59 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-22 10:53:31 -0400, Tom Lane wrote:\n>> I'm skeptical of that, mainly because it doesn't work in old servers,\n\n> I think we can address that, if we think it's overall a promising approach to\n> pursue. E.g. if we don't need the indexes, we can make it = ANY().\n\nHmm ... yeah, I guess we could get away with that. It might not scale\nas nicely to a huge database, but probably dumping a huge database\nfrom an ancient server isn't all that interesting.\n\nI'm inclined to think that it could be sane to make getTableAttrs\nand getIndexes use this style, but we probably still want functions\nand such to use per-object queries. In those other catalogs there\nare many built-in objects that we don't really care about. The\nprepared-queries hack I was working on last night is probably plenty\ngood enough there, and it's a much less invasive patch.\n\nWere you planning to pursue this further, or did you want me to?\nI'd want to layer it on top of the work I did at [1], else there's\ngoing to be lots of merge conflicts.\n\n\t\t\tregards, tom lane\n\n[1] https://www.postgresql.org/message-id/2273648.1634764485%40sss.pgh.pa.us\n\n\n","msg_date":"Fri, 22 Oct 2021 11:54:13 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n>> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\n>>> (a) the executable size increases by a few KB --- apparently, even\n>>> the minimum subset of simplehash.h's functionality is code-wasteful.\n\n> If I prevent the compiler from inlining findObjectByCatalogId() in all the\n> find*ByOid() routines, your version is smaller than master even without other\n> changes.\n\nHmm ... seems to depend a lot on which compiler you use.\n\nI was originally looking at it with gcc 8.4.1 (RHEL8 default),\nx86_64. On that, adding pg_noinline to findObjectByCatalogId\nhelps a little, but it's still 3.6K bigger than HEAD.\n\nI then tried gcc 11.2.1/x86_64, finding that the patch adds\nabout 2K and pg_noinline makes no difference.\n\nI also tried it on Apple's clang 13.0.0, both x86_64 and ARM\nversions. On that, the change seems to be a wash or slightly\nsmaller, with maybe a little benefit from pg_noinline but not\nmuch. It's hard to tell for sure because size(1) seems to be\nrounding off to a page boundary on that platform.\n\nAnyway, these are all sub-one-percent changes in the code\nsize, so probably we should not sweat that much about it.\nI'm kind of leaning now towards pushing the patch, just\non the grounds that getting rid of all those single-purpose\nindex arrays (and likely future need for more of them)\nis worth it from a maintenance perspective.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 13:32:30 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi, \n\nOn October 22, 2021 8:54:13 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>Andres Freund <andres@anarazel.de> writes:\n>> On 2021-10-22 10:53:31 -0400, Tom Lane wrote:\n>>> I'm skeptical of that, mainly because it doesn't work in old servers,\n>\n>> I think we can address that, if we think it's overall a promising approach to\n>> pursue. E.g. if we don't need the indexes, we can make it = ANY().\n>\n>Hmm ... yeah, I guess we could get away with that. It might not scale\n>as nicely to a huge database, but probably dumping a huge database\n>from an ancient server isn't all that interesting.\n\nI think compared to the overhead of locking that many tables and sending O(N) queries it shouldn't be a huge factor.\n\nOne think that looks like it might be worth doing, and not hard, is to use single row mode. No need to materialize all that data twice in memory.\n\n\nAt a later stage it might be worth sending the array separately as a parameter. Perhaps even binary encoded.\n\n\n>I'm inclined to think that it could be sane to make getTableAttrs\n>and getIndexes use this style, but we probably still want functions\n>and such to use per-object queries. In those other catalogs there\n>are many built-in objects that we don't really care about. The\n>prepared-queries hack I was working on last night is probably plenty\n>good enough there, and it's a much less invasive patch.\n\nYes, that seems reasonable. I think the triggers query would benefit from the batch approach though - I see that taking a long time in aggregate on a test database with many tables I had around (partially due to the self join), and we already materialize it.\n\n\n>Were you planning to pursue this further, or did you want me to?\n\nIt seems too nice an improvement to drop on the floor. That said, I don't really have the mental bandwidth to pursue this beyond the POC stage - it seemed complicated enough that suggestion accompanied by a prototype was a good idea. So I'd be happy for you to incorporate this into your other changes.\n\n\n>I'd want to layer it on top of the work I did at [1], else there's\n>going to be lots of merge conflicts.\n\nMakes sense. Even if nobody else were doing anything in the area I'd probably want to split it into one commit creating the query once, and then separately implement the batching.\n\nRegards,\n\nAndres\n-- \nSent from my Android device with K-9 Mail. Please excuse my brevity.\n\n\n","msg_date":"Fri, 22 Oct 2021 11:30:38 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On October 22, 2021 8:54:13 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Were you planning to pursue this further, or did you want me to?\n\n> It seems too nice an improvement to drop on the floor. That said, I don't really have the mental bandwidth to pursue this beyond the POC stage - it seemed complicated enough that suggestion accompanied by a prototype was a good idea. So I'd be happy for you to incorporate this into your other changes.\n\nCool, I'll see what I can do with it, as long as I'm poking around\nin the area.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 14:36:44 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi, \n\nOn October 22, 2021 10:32:30 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>Andres Freund <andres@anarazel.de> writes:\n>>> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\n>>>> (a) the executable size increases by a few KB --- apparently, even\n>>>> the minimum subset of simplehash.h's functionality is code-wasteful.\n>\n>> If I prevent the compiler from inlining findObjectByCatalogId() in all the\n>> find*ByOid() routines, your version is smaller than master even without other\n>> changes.\n>\n>Hmm ... seems to depend a lot on which compiler you use.\n\nInline heuristics change a lot over time, so that'd make sense.\n\nI see some win by marking pg_log_error cold. That might be useful more generally too.\n\n\nWhich made me look at the code invoking it from simplehash. I think the patch that made simplehash work in frontend code isn't quite right, because pg_log_error() returns...\n\n\nWonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\n\n\n>Anyway, these are all sub-one-percent changes in the code\n>size, so probably we should not sweat that much about it.\n>I'm kind of leaning now towards pushing the patch, just\n>on the grounds that getting rid of all those single-purpose\n>index arrays (and likely future need for more of them)\n>is worth it from a maintenance perspective.\n\n+1\n\nThe only thought I had wrt the patch is that I'd always create the hash table. That way the related branches can be removed, which is a win code size wise (as well as speed presumably, but I think we're far away from that mattering).\n\n\nThis type of code is where I most wish for a language with proper generic data types/containers...\n\nAndres\n-- \nSent from my Android device with K-9 Mail. Please excuse my brevity.\n\n\n","msg_date":"Fri, 22 Oct 2021 11:44:21 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> Which made me look at the code invoking it from simplehash. I think the patch that made simplehash work in frontend code isn't quite right, because pg_log_error() returns...\n\nIndeed, that's broken. I guess we want pg_log_fatal then exit(1).\n\n> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\n\nSeems plausible --- you want me to go change that?\n\n> The only thought I had wrt the patch is that I'd always create the hash\n> table.\n\nThat'd require adding an explicit init function and figuring out where to\ncall it, which we could do but I didn't (and don't) think it's worth the\ntrouble. One more branch here isn't going to matter, especially given\nthat we can't even measure the presumed macro improvement.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 15:41:07 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"I wrote:\n> Andres Freund <andres@anarazel.de> writes:\n>> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\n\n> Seems plausible --- you want me to go change that?\n\nHmm, harder than it sounds. If I remove \"inline\" from SH_SCOPE then\nthe compiler complains about unreferenced static functions, while\nif I leave it there than adding pg_noinline causes a complaint about\nconflicting options. Seems like we need a less quick-and-dirty\napproach to dealing with unnecessary simplehash support functions.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 16:32:39 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nThanks for pushing the error handling cleanup etc!\n\nOn 2021-10-22 16:32:39 -0400, Tom Lane wrote:\n> I wrote:\n> > Andres Freund <andres@anarazel.de> writes:\n> >> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\n>\n> > Seems plausible --- you want me to go change that?\n>\n> Hmm, harder than it sounds. If I remove \"inline\" from SH_SCOPE then\n> the compiler complains about unreferenced static functions, while\n> if I leave it there than adding pg_noinline causes a complaint about\n> conflicting options.\n\nThe easy way out would be to to not declare SH_GROW inside SH_DECLARE - that'd\ncurrently work, because there aren't any calls to grow from outside of\nsimplehash.h. The comment says:\n * ... But resizing to the exact input size can be advantageous\n * performance-wise, when known at some point.\n\nBut perhaps that's sufficiently served to create the table with the correct\nsize immediately?\n\nIf we were to go for that, we'd just put SH_GROW in the SH_DEFINE section not\nuse SH_SCOPE, but just static. That works here, and I have some hope it'd not\ncause warnings on other compilers either, because there'll be references from\nthe other inline functions. Even if there's a SH_SCOPE=static inline\nsimplehash use inside a header and there aren't any callers in a TU, there'd\nstill be static inline references to it.\n\n\nAnother alternative would be to use __attribute__((unused)) or such on\nnon-static-inline functions that might or might not be used.\n\n\n> Seems like we need a less quick-and-dirty approach to dealing with\n> unnecessary simplehash support functions.\n\nI don't think the problem is unnecessary ones? It's \"cold\" functions we don't\nwant to have inlined into larger functions.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 10:50:28 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-22 16:32:39 -0400, Tom Lane wrote:\n>> Hmm, harder than it sounds. If I remove \"inline\" from SH_SCOPE then\n>> the compiler complains about unreferenced static functions, while\n>> if I leave it there than adding pg_noinline causes a complaint about\n>> conflicting options.\n\n> The easy way out would be to to not declare SH_GROW inside SH_DECLARE - that'd\n> currently work, because there aren't any calls to grow from outside of\n> simplehash.h.\n\nSeems like a reasonable approach. If somebody wanted to call that\nfrom outside, I'd personally feel they were getting way too friendly\nwith the implementation.\n\n>> Seems like we need a less quick-and-dirty approach to dealing with\n>> unnecessary simplehash support functions.\n\n> I don't think the problem is unnecessary ones?\n\nI was thinking about the stuff like SH_ITERATE, which you might or\nmight not have use for in any particular file. In the case at hand\nhere, a file that doesn't call SH_INSERT would be at risk of getting\nunused-function complaints about SH_GROW. But as you say, if we do\nfind that happening, __attribute__((unused)) would probably be\nenough to silence it.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 13:58:06 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-25 13:58:06 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> >> Seems like we need a less quick-and-dirty approach to dealing with\n> >> unnecessary simplehash support functions.\n> \n> > I don't think the problem is unnecessary ones?\n> \n> I was thinking about the stuff like SH_ITERATE, which you might or\n> might not have use for in any particular file. In the case at hand\n> here, a file that doesn't call SH_INSERT would be at risk of getting\n> unused-function complaints about SH_GROW. But as you say, if we do\n> find that happening, __attribute__((unused)) would probably be\n> enough to silence it.\n\nI was hoping that a reference from a static inline function ought to be\nsufficient to prevent warning about an unused-static-not-inline function, even\nif the referencing static inline function is unused... It does work that way\nwith at least the last few versions of gcc (tested 8-11) and clang (tested 6.0\nto 13).\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 11:39:46 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Experimenting with hash tables inside pg_dump"}],"string":"[\n {\n \"msg_contents\": \"Today, pg_dump does a lot of internal lookups via binary search\\nin presorted arrays. I thought it might improve matters\\nto replace those binary searches with hash tables, theoretically\\nconverting O(log N) searches into O(1) searches. So I tried making\\na hash table indexed by CatalogId (tableoid+oid) with simplehash.h,\\nand replacing as many data structures as I could with that.\\n\\nThis makes the code shorter and (IMO anyway) cleaner, but\\n\\n(a) the executable size increases by a few KB --- apparently, even\\nthe minimum subset of simplehash.h's functionality is code-wasteful.\\n\\n(b) I couldn't measure any change in performance at all. I tried\\nit on the regression database and on a toy DB with 10000 simple\\ntables. Maybe on a really large DB you'd notice some difference,\\nbut I'm not very optimistic now.\\n\\nSo this experiment feels like a failure, but I thought I'd post\\nthe patch and results for the archives' sake. Maybe somebody\\nwill think of a way to improve matters. Or maybe it's worth\\ndoing just to shorten the code?\\n\\n\\t\\t\\tregards, tom lane\",\n \"msg_date\": \"Thu, 21 Oct 2021 18:27:25 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"On 10/21/21, 3:29 PM, \\\"Tom Lane\\\" <tgl@sss.pgh.pa.us> wrote:\\r\\n> (b) I couldn't measure any change in performance at all. I tried\\r\\n> it on the regression database and on a toy DB with 10000 simple\\r\\n> tables. Maybe on a really large DB you'd notice some difference,\\r\\n> but I'm not very optimistic now.\\r\\n\\r\\nI wonder how many tables you'd need to start seeing a difference.\\r\\nThere are certainly databases out there with many more than 10,000\\r\\ntables. I'll look into this...\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 23:13:11 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-21 18:27:25 -0400, Tom Lane wrote:\\n> Today, pg_dump does a lot of internal lookups via binary search\\n> in presorted arrays. I thought it might improve matters\\n> to replace those binary searches with hash tables, theoretically\\n> converting O(log N) searches into O(1) searches. So I tried making\\n> a hash table indexed by CatalogId (tableoid+oid) with simplehash.h,\\n> and replacing as many data structures as I could with that.\\n\\nThat does sound like a good idea in theory...\\n\\n\\n> This makes the code shorter and (IMO anyway) cleaner, but\\n> \\n> (a) the executable size increases by a few KB --- apparently, even\\n> the minimum subset of simplehash.h's functionality is code-wasteful.\\n\\nHm. Surprised a bit by that. In an optimized build the difference is a\\nsmaller, at least.\\n\\noptimized:\\n text\\t data\\t bss\\t dec\\t hex\\tfilename\\n 448066\\t 7048\\t 1368\\t 456482\\t 6f722\\tsrc/bin/pg_dump/pg_dump\\n 447530\\t 7048\\t 1496\\t 456074\\t 6f58a\\tsrc/bin/pg_dump/pg_dump.orig\\n\\ndebug:\\n text\\t data\\t bss\\t dec\\t hex\\tfilename\\n 516883\\t 7024\\t 1352\\t 525259\\t 803cb\\tsrc/bin/pg_dump/pg_dump\\n 509819\\t 7024\\t 1480\\t 518323\\t 7e8b3\\tsrc/bin/pg_dump/pg_dump.orig\\n\\nThe fact that optimization plays such a role makes me wonder if a good chunk\\nof the difference is the slightly more complicated find{Type,Func,...}ByOid()\\nfunctions.\\n\\n\\n> (b) I couldn't measure any change in performance at all. I tried\\n> it on the regression database and on a toy DB with 10000 simple\\n> tables. Maybe on a really large DB you'd notice some difference,\\n> but I'm not very optimistic now.\\n\\nDid you measure runtime of pg_dump, or how much CPU it used? I think a lot of\\nthe time the backend is a bigger bottleneck than pg_dump...\\n\\nFor the regression test DB the majority of the time seems to be spent below\\ntwo things:\\n1) libpq\\n2) sortDumpableObjects().\\n\\nI don't think 2) hits the binary search / hashtable path?\\n\\n\\nIt does seem interesting that a substantial part of the time is spent in/below\\nPQexec() and PQfnumber(). Especially the latter shouldn't be too hard to\\noptimize away...\\n\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 16:37:57 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"On 10/21/21, 4:14 PM, \\\"Bossart, Nathan\\\" <bossartn@amazon.com> wrote:\\r\\n> On 10/21/21, 3:29 PM, \\\"Tom Lane\\\" <tgl@sss.pgh.pa.us> wrote:\\r\\n>> (b) I couldn't measure any change in performance at all. I tried\\r\\n>> it on the regression database and on a toy DB with 10000 simple\\r\\n>> tables. Maybe on a really large DB you'd notice some difference,\\r\\n>> but I'm not very optimistic now.\\r\\n>\\r\\n> I wonder how many tables you'd need to start seeing a difference.\\r\\n> There are certainly databases out there with many more than 10,000\\r\\n> tables. I'll look into this...\\r\\n\\r\\nWell, I tested with 200,000 tables and saw no difference with this.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 23:59:57 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> Did you measure runtime of pg_dump, or how much CPU it used?\\n\\nI was looking mostly at wall-clock runtime, though I did notice\\nthat the CPU time looked about the same too.\\n\\n> I think a lot of\\n> the time the backend is a bigger bottleneck than pg_dump...\\n\\nYeah, that. I tried doing a system-wide \\\"perf\\\" measurement, and soon\\nrealized that a big fraction of the time for a \\\"pg_dump -s\\\" run is\\nbeing spent in the planner :-(. I'm currently experimenting with\\nPREPARE'ing pg_dump's repetitive queries, and it's looking very\\npromising. More later.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 20:22:56 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-21 16:37:57 -0700, Andres Freund wrote:\\n> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\\n> > (a) the executable size increases by a few KB --- apparently, even\\n> > the minimum subset of simplehash.h's functionality is code-wasteful.\\n> \\n> Hm. Surprised a bit by that. In an optimized build the difference is a\\n> smaller, at least.\\n> \\n> optimized:\\n> text\\t data\\t bss\\t dec\\t hex\\tfilename\\n> 448066\\t 7048\\t 1368\\t 456482\\t 6f722\\tsrc/bin/pg_dump/pg_dump\\n> 447530\\t 7048\\t 1496\\t 456074\\t 6f58a\\tsrc/bin/pg_dump/pg_dump.orig\\n> \\n> debug:\\n> text\\t data\\t bss\\t dec\\t hex\\tfilename\\n> 516883\\t 7024\\t 1352\\t 525259\\t 803cb\\tsrc/bin/pg_dump/pg_dump\\n> 509819\\t 7024\\t 1480\\t 518323\\t 7e8b3\\tsrc/bin/pg_dump/pg_dump.orig\\n> \\n> The fact that optimization plays such a role makes me wonder if a good chunk\\n> of the difference is the slightly more complicated find{Type,Func,...}ByOid()\\n> functions.\\n\\nIt's not that.\\n\\nIn a debug build a good chunk of it is due to a bunch of Assert()s. Another\\npart is that trivial helper functions like SH_PREV() don't get inlined.\\n\\nThe increase for an optimized build seems to boil down to pg_log_error()\\ninvocations. If I replace those with an exit(1), the resulting binaries are\\nwithin 100 byte.\\n\\nIf I prevent the compiler from inlining findObjectByCatalogId() in all the\\nfind*ByOid() routines, your version is smaller than master even without other\\nchanges.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 17:47:15 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-21 20:22:56 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> Yeah, that. I tried doing a system-wide \\\"perf\\\" measurement, and soon\\n> realized that a big fraction of the time for a \\\"pg_dump -s\\\" run is\\n> being spent in the planner :-(.\\n\\nA trick for seeing the proportions of this easily in perf is to start both\\npostgres and pg_dump pinned to a specific CPU, and profile that cpu. That gets\\nrid of most of the noise of other programs etc.\\n\\n\\n\\n> I'm currently experimenting with\\n> PREPARE'ing pg_dump's repetitive queries, and it's looking very\\n> promising. More later.\\n\\nGood idea.\\n\\nI wonder though if for some of them we should instead replace the per-object\\nqueries with one query returning the information for all objects of a type. It\\ndoesn't make all that much sense that we build and send one query for each\\ntable and index.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 18:09:36 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> I wonder though if for some of them we should instead replace the per-object\\n> queries with one query returning the information for all objects of a type. It\\n> doesn't make all that much sense that we build and send one query for each\\n> table and index.\\n\\nThe trick is the problem I alluded to in another thread: it's not safe to\\ndo stuff like pg_get_expr() on tables we don't have lock on.\\n\\nI've thought about doing something like\\n\\nSELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\\n\\nbut in cases with tens of thousands of tables, it seems unlikely that\\nthat's going to behave all that nicely.\\n\\nThe *real* fix, I suppose, would be to fix all those catalog-inspection\\nfunctions so that they operate with respect to the query's snapshot.\\nBut that's not a job I'm volunteering for. Besides which, pg_dump\\nstill has to cope with back-rev servers where it wouldn't be safe.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 22:13:22 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-21 22:13:22 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> > I wonder though if for some of them we should instead replace the per-object\\n> > queries with one query returning the information for all objects of a type. It\\n> > doesn't make all that much sense that we build and send one query for each\\n> > table and index.\\n> \\n> The trick is the problem I alluded to in another thread: it's not safe to\\n> do stuff like pg_get_expr() on tables we don't have lock on.\\n\\nI was looking at getTableAttrs() - sending one query instead of #tables\\nqueries yields a quite substantial speedup in a quick prototype. And I don't\\nthink it changes anything around locking semantics.\\n\\n\\n> I've thought about doing something like\\n> \\n> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\\n> \\n> but in cases with tens of thousands of tables, it seems unlikely that\\n> that's going to behave all that nicely.\\n\\nThat's kinda what I'm doing in the quick hack. But instead of using IN(...) I\\nmade it unnest('{oid, oid, ...}'), that scales much better.\\n\\nA pg_dump --schema-only of the regression database goes from\\n\\nreal\\t0m0.675s\\nuser\\t0m0.039s\\nsys\\t0m0.029s\\n\\nto\\n\\nreal\\t0m0.477s\\nuser\\t0m0.037s\\nsys\\t0m0.020s\\n\\nwhich isn't half-bad.\\n\\nThere's a few more cases like this I think. But most are harder because the\\ndumping happens one-by-one from dumpDumpableObject(). The relatively easy but\\nsubstantial cases I could find quickly were getIndexes(), getConstraints(),\\ngetTriggers()\\n\\n\\nTo see where it's worth putting in time it'd be useful if getSchemaData() in\\nverbose mode printed timing information...\\n\\n\\n> The *real* fix, I suppose, would be to fix all those catalog-inspection\\n> functions so that they operate with respect to the query's snapshot.\\n> But that's not a job I'm volunteering for. Besides which, pg_dump\\n> still has to cope with back-rev servers where it wouldn't be safe.\\n\\nYea, that's not a small change :(. I suspect that we'd need a bunch of new\\ncaching infrastructure to make that reasonably performant, since this\\npresumably couldn't use syscache etc.\\n\\nGreetings,\\n\\nAndres Freund\",\n \"msg_date\": \"Thu, 21 Oct 2021 22:59:39 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-21 22:13:22 -0400, Tom Lane wrote:\\n>> I've thought about doing something like\\n>> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\\n>> but in cases with tens of thousands of tables, it seems unlikely that\\n>> that's going to behave all that nicely.\\n\\n> That's kinda what I'm doing in the quick hack. But instead of using IN(...) I\\n> made it unnest('{oid, oid, ...}'), that scales much better.\\n\\nI'm skeptical of that, mainly because it doesn't work in old servers,\\nand I really don't want to maintain two fundamentally different\\nversions of getTableAttrs(). I don't think you actually need the\\nmulti-array form of unnest() here --- we know the TableInfo array\\nis in OID order --- but even the single-array form only works\\nback to 8.4.\\n\\nHowever ... looking through getTableAttrs' main query, it seems\\nlike the only thing there that's potentially unsafe is the\\n\\\"format_type(t.oid, a.atttypmod)\\\" call. I wonder if it could be\\nsane to convert it into a single query that just scans all of\\npg_attribute, and then deal with creating the formatted type names\\nseparately, perhaps with an improved version of getFormattedTypeName\\nthat could cache the results for non-default typmods. The main\\nknock on this approach is the temptation for somebody to stick some\\nunsafe function into the query in future. We could stick a big fat\\nwarning comment into the code, but lately I despair of people reading\\ncomments.\\n\\n> To see where it's worth putting in time it'd be useful if getSchemaData() in\\n> verbose mode printed timing information...\\n\\nI've been running test cases with log_min_duration_statement = 0,\\nwhich serves well enough.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 10:53:31 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-22 10:53:31 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> > On 2021-10-21 22:13:22 -0400, Tom Lane wrote:\\n> >> I've thought about doing something like\\n> >> SELECT unsafe-functions FROM pg_class WHERE oid IN (someoid, someoid, ...)\\n> >> but in cases with tens of thousands of tables, it seems unlikely that\\n> >> that's going to behave all that nicely.\\n> \\n> > That's kinda what I'm doing in the quick hack. But instead of using IN(...) I\\n> > made it unnest('{oid, oid, ...}'), that scales much better.\\n> \\n> I'm skeptical of that, mainly because it doesn't work in old servers,\\n> and I really don't want to maintain two fundamentally different\\n> versions of getTableAttrs(). I don't think you actually need the\\n> multi-array form of unnest() here --- we know the TableInfo array\\n> is in OID order --- but even the single-array form only works\\n> back to 8.4.\\n\\nI think we can address that, if we think it's overall a promising approach to\\npursue. E.g. if we don't need the indexes, we can make it = ANY().\\n\\n\\n> However ... looking through getTableAttrs' main query, it seems\\n> like the only thing there that's potentially unsafe is the\\n> \\\"format_type(t.oid, a.atttypmod)\\\" call.\\n\\nI assume the default expression bit would also be unsafe?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 08:21:59 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-22 10:53:31 -0400, Tom Lane wrote:\\n>> I'm skeptical of that, mainly because it doesn't work in old servers,\\n\\n> I think we can address that, if we think it's overall a promising approach to\\n> pursue. E.g. if we don't need the indexes, we can make it = ANY().\\n\\nHmm ... yeah, I guess we could get away with that. It might not scale\\nas nicely to a huge database, but probably dumping a huge database\\nfrom an ancient server isn't all that interesting.\\n\\nI'm inclined to think that it could be sane to make getTableAttrs\\nand getIndexes use this style, but we probably still want functions\\nand such to use per-object queries. In those other catalogs there\\nare many built-in objects that we don't really care about. The\\nprepared-queries hack I was working on last night is probably plenty\\ngood enough there, and it's a much less invasive patch.\\n\\nWere you planning to pursue this further, or did you want me to?\\nI'd want to layer it on top of the work I did at [1], else there's\\ngoing to be lots of merge conflicts.\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://www.postgresql.org/message-id/2273648.1634764485%40sss.pgh.pa.us\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 11:54:13 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n>> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\\n>>> (a) the executable size increases by a few KB --- apparently, even\\n>>> the minimum subset of simplehash.h's functionality is code-wasteful.\\n\\n> If I prevent the compiler from inlining findObjectByCatalogId() in all the\\n> find*ByOid() routines, your version is smaller than master even without other\\n> changes.\\n\\nHmm ... seems to depend a lot on which compiler you use.\\n\\nI was originally looking at it with gcc 8.4.1 (RHEL8 default),\\nx86_64. On that, adding pg_noinline to findObjectByCatalogId\\nhelps a little, but it's still 3.6K bigger than HEAD.\\n\\nI then tried gcc 11.2.1/x86_64, finding that the patch adds\\nabout 2K and pg_noinline makes no difference.\\n\\nI also tried it on Apple's clang 13.0.0, both x86_64 and ARM\\nversions. On that, the change seems to be a wash or slightly\\nsmaller, with maybe a little benefit from pg_noinline but not\\nmuch. It's hard to tell for sure because size(1) seems to be\\nrounding off to a page boundary on that platform.\\n\\nAnyway, these are all sub-one-percent changes in the code\\nsize, so probably we should not sweat that much about it.\\nI'm kind of leaning now towards pushing the patch, just\\non the grounds that getting rid of all those single-purpose\\nindex arrays (and likely future need for more of them)\\nis worth it from a maintenance perspective.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 13:32:30 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi, \\n\\nOn October 22, 2021 8:54:13 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>Andres Freund <andres@anarazel.de> writes:\\n>> On 2021-10-22 10:53:31 -0400, Tom Lane wrote:\\n>>> I'm skeptical of that, mainly because it doesn't work in old servers,\\n>\\n>> I think we can address that, if we think it's overall a promising approach to\\n>> pursue. E.g. if we don't need the indexes, we can make it = ANY().\\n>\\n>Hmm ... yeah, I guess we could get away with that. It might not scale\\n>as nicely to a huge database, but probably dumping a huge database\\n>from an ancient server isn't all that interesting.\\n\\nI think compared to the overhead of locking that many tables and sending O(N) queries it shouldn't be a huge factor.\\n\\nOne think that looks like it might be worth doing, and not hard, is to use single row mode. No need to materialize all that data twice in memory.\\n\\n\\nAt a later stage it might be worth sending the array separately as a parameter. Perhaps even binary encoded.\\n\\n\\n>I'm inclined to think that it could be sane to make getTableAttrs\\n>and getIndexes use this style, but we probably still want functions\\n>and such to use per-object queries. In those other catalogs there\\n>are many built-in objects that we don't really care about. The\\n>prepared-queries hack I was working on last night is probably plenty\\n>good enough there, and it's a much less invasive patch.\\n\\nYes, that seems reasonable. I think the triggers query would benefit from the batch approach though - I see that taking a long time in aggregate on a test database with many tables I had around (partially due to the self join), and we already materialize it.\\n\\n\\n>Were you planning to pursue this further, or did you want me to?\\n\\nIt seems too nice an improvement to drop on the floor. That said, I don't really have the mental bandwidth to pursue this beyond the POC stage - it seemed complicated enough that suggestion accompanied by a prototype was a good idea. So I'd be happy for you to incorporate this into your other changes.\\n\\n\\n>I'd want to layer it on top of the work I did at [1], else there's\\n>going to be lots of merge conflicts.\\n\\nMakes sense. Even if nobody else were doing anything in the area I'd probably want to split it into one commit creating the query once, and then separately implement the batching.\\n\\nRegards,\\n\\nAndres\\n-- \\nSent from my Android device with K-9 Mail. Please excuse my brevity.\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 11:30:38 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On October 22, 2021 8:54:13 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Were you planning to pursue this further, or did you want me to?\\n\\n> It seems too nice an improvement to drop on the floor. That said, I don't really have the mental bandwidth to pursue this beyond the POC stage - it seemed complicated enough that suggestion accompanied by a prototype was a good idea. So I'd be happy for you to incorporate this into your other changes.\\n\\nCool, I'll see what I can do with it, as long as I'm poking around\\nin the area.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 14:36:44 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi, \\n\\nOn October 22, 2021 10:32:30 AM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>Andres Freund <andres@anarazel.de> writes:\\n>>> On 2021-10-21 18:27:25 -0400, Tom Lane wrote:\\n>>>> (a) the executable size increases by a few KB --- apparently, even\\n>>>> the minimum subset of simplehash.h's functionality is code-wasteful.\\n>\\n>> If I prevent the compiler from inlining findObjectByCatalogId() in all the\\n>> find*ByOid() routines, your version is smaller than master even without other\\n>> changes.\\n>\\n>Hmm ... seems to depend a lot on which compiler you use.\\n\\nInline heuristics change a lot over time, so that'd make sense.\\n\\nI see some win by marking pg_log_error cold. That might be useful more generally too.\\n\\n\\nWhich made me look at the code invoking it from simplehash. I think the patch that made simplehash work in frontend code isn't quite right, because pg_log_error() returns...\\n\\n\\nWonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\\n\\n\\n>Anyway, these are all sub-one-percent changes in the code\\n>size, so probably we should not sweat that much about it.\\n>I'm kind of leaning now towards pushing the patch, just\\n>on the grounds that getting rid of all those single-purpose\\n>index arrays (and likely future need for more of them)\\n>is worth it from a maintenance perspective.\\n\\n+1\\n\\nThe only thought I had wrt the patch is that I'd always create the hash table. That way the related branches can be removed, which is a win code size wise (as well as speed presumably, but I think we're far away from that mattering).\\n\\n\\nThis type of code is where I most wish for a language with proper generic data types/containers...\\n\\nAndres\\n-- \\nSent from my Android device with K-9 Mail. Please excuse my brevity.\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 11:44:21 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> Which made me look at the code invoking it from simplehash. I think the patch that made simplehash work in frontend code isn't quite right, because pg_log_error() returns...\\n\\nIndeed, that's broken. I guess we want pg_log_fatal then exit(1).\\n\\n> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\\n\\nSeems plausible --- you want me to go change that?\\n\\n> The only thought I had wrt the patch is that I'd always create the hash\\n> table.\\n\\nThat'd require adding an explicit init function and figuring out where to\\ncall it, which we could do but I didn't (and don't) think it's worth the\\ntrouble. One more branch here isn't going to matter, especially given\\nthat we can't even measure the presumed macro improvement.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 15:41:07 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"I wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n>> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\\n\\n> Seems plausible --- you want me to go change that?\\n\\nHmm, harder than it sounds. If I remove \\\"inline\\\" from SH_SCOPE then\\nthe compiler complains about unreferenced static functions, while\\nif I leave it there than adding pg_noinline causes a complaint about\\nconflicting options. Seems like we need a less quick-and-dirty\\napproach to dealing with unnecessary simplehash support functions.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 16:32:39 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nThanks for pushing the error handling cleanup etc!\\n\\nOn 2021-10-22 16:32:39 -0400, Tom Lane wrote:\\n> I wrote:\\n> > Andres Freund <andres@anarazel.de> writes:\\n> >> Wonder if we should mark simplehash's grow as noinline? Even with a single caller it seems better to not inline it to remove register allocator pressure.\\n>\\n> > Seems plausible --- you want me to go change that?\\n>\\n> Hmm, harder than it sounds. If I remove \\\"inline\\\" from SH_SCOPE then\\n> the compiler complains about unreferenced static functions, while\\n> if I leave it there than adding pg_noinline causes a complaint about\\n> conflicting options.\\n\\nThe easy way out would be to to not declare SH_GROW inside SH_DECLARE - that'd\\ncurrently work, because there aren't any calls to grow from outside of\\nsimplehash.h. The comment says:\\n * ... But resizing to the exact input size can be advantageous\\n * performance-wise, when known at some point.\\n\\nBut perhaps that's sufficiently served to create the table with the correct\\nsize immediately?\\n\\nIf we were to go for that, we'd just put SH_GROW in the SH_DEFINE section not\\nuse SH_SCOPE, but just static. That works here, and I have some hope it'd not\\ncause warnings on other compilers either, because there'll be references from\\nthe other inline functions. Even if there's a SH_SCOPE=static inline\\nsimplehash use inside a header and there aren't any callers in a TU, there'd\\nstill be static inline references to it.\\n\\n\\nAnother alternative would be to use __attribute__((unused)) or such on\\nnon-static-inline functions that might or might not be used.\\n\\n\\n> Seems like we need a less quick-and-dirty approach to dealing with\\n> unnecessary simplehash support functions.\\n\\nI don't think the problem is unnecessary ones? It's \\\"cold\\\" functions we don't\\nwant to have inlined into larger functions.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:50:28 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-22 16:32:39 -0400, Tom Lane wrote:\\n>> Hmm, harder than it sounds. If I remove \\\"inline\\\" from SH_SCOPE then\\n>> the compiler complains about unreferenced static functions, while\\n>> if I leave it there than adding pg_noinline causes a complaint about\\n>> conflicting options.\\n\\n> The easy way out would be to to not declare SH_GROW inside SH_DECLARE - that'd\\n> currently work, because there aren't any calls to grow from outside of\\n> simplehash.h.\\n\\nSeems like a reasonable approach. If somebody wanted to call that\\nfrom outside, I'd personally feel they were getting way too friendly\\nwith the implementation.\\n\\n>> Seems like we need a less quick-and-dirty approach to dealing with\\n>> unnecessary simplehash support functions.\\n\\n> I don't think the problem is unnecessary ones?\\n\\nI was thinking about the stuff like SH_ITERATE, which you might or\\nmight not have use for in any particular file. In the case at hand\\nhere, a file that doesn't call SH_INSERT would be at risk of getting\\nunused-function complaints about SH_GROW. But as you say, if we do\\nfind that happening, __attribute__((unused)) would probably be\\nenough to silence it.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:58:06 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 13:58:06 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> >> Seems like we need a less quick-and-dirty approach to dealing with\\n> >> unnecessary simplehash support functions.\\n> \\n> > I don't think the problem is unnecessary ones?\\n> \\n> I was thinking about the stuff like SH_ITERATE, which you might or\\n> might not have use for in any particular file. In the case at hand\\n> here, a file that doesn't call SH_INSERT would be at risk of getting\\n> unused-function complaints about SH_GROW. But as you say, if we do\\n> find that happening, __attribute__((unused)) would probably be\\n> enough to silence it.\\n\\nI was hoping that a reference from a static inline function ought to be\\nsufficient to prevent warning about an unused-static-not-inline function, even\\nif the referencing static inline function is unused... It does work that way\\nwith at least the last few versions of gcc (tested 8-11) and clang (tested 6.0\\nto 13).\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:39:46 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Experimenting with hash tables inside pg_dump\"\n }\n]","isConversational":false}}},{"rowIdx":52981,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"I returned to the 1995 paper \"Efficient Search of Multidimensional\nB-Trees\" [1] as part of the process of reviewing v39 of the skip scan\npatch, which was posted back in May. It's a great paper, and anybody\ninvolved in the skip scan effort should read it thoroughly (if they\nhaven't already). It's easy to see why people get excited about skip\nscan [2]. But there is a bigger picture here.\n\nI don't necessarily expect to come away from this discussion with a\nmuch better high level architecture for the patch, or any kind of\ndeeper insight, or even a frame of reference for further discussion. I\njust think that we ought to *try* to impose some order on this stuff.\n\nLike many difficult patches, the skip scan patch is not so much\ntroubled by problems with the implementation as it is troubled by\n*ambiguity* about the design. Particularly concerning how skip scan\nmeshes with existing designs, as well as future designs --\nparticularly designs for other MDAM techniques. I've started this\nthread to have a big picture conversation about how to think about\nthese things. Many other MDAM techniques also seem highly appealing.\nMuch of the MDAM stuff is for data warehousing use-cases, while skip\nscan/loose index scan is seen as more of an OLTP thing. But they are\nstill related, clearly.\n\nI'd like to also talk about another patch, that ISTM had that same\nquality -- it was also held back by high level design uncertainty. Back in 2018,\nTom abandoned a patch that transformed a star-schema style query with\nleft outer joins on dimension tables with OR conditions, into an\nequivalent query that UNIONs together 2 distinct queries [3][4].\n\nBelieve it or not, I am now reminded of that patch by the example of\n\"IN() Lists\", from page 5 of the paper. We see this example SQL query:\n\nSELECT date, item_class, store, sum(total_sales)\nFROM sales\nWHERE date between '06/01/95' and '06/30/95' and\nitem_class IN (20,35,50) and\nstore IN (200,250)\nGROUP BY dept, date, item_class, store;\n\nGranted, this SQL might not seem directly relevant to Tom's patch at\nfirst -- there is no join for the optimizer to even try to eliminate,\nwhich was the whole basis of Jim Nasby's original complaint, which is\nwhat spurred Tom to write the patch in the first place. But hear me\nout: there is still a fact table (the sales table) with some\ndimensions (the 'D' from 'MDAM') shown in the predicate. Moreover, the\ntable (and this SQL query) drives discussion of an optimization\ninvolving transforming a predicate with many ORs (which is explicitly\nsaid to be logically/semantically equivalent to the IN() lists from\nthe query). They transform the query into a bunch of disjunct clauses\nthat can easily be independently executed, and combined at the end\n(see also \"General OR Optimization\" on page 6 of the paper).\n\nAlso...I'm not entirely sure that the intended underlying \"physical\nplan\" is truly free of join-like scans. If you squint just right, you\nmight see something that you could think of as a \"physical join\" (at\nleast very informally). The whole point of this particular \"IN()\nLists\" example is that we get to the following, for each distinct\n\"dept\" and \"date\" in the table:\n\ndept=1, date='06/04/95', item_class=20, store=200\ndept=1, date='06/04/95', item_class=20, store=250\ndept=1, date='06/04/95', item_class=35, store=200\ndept=1, date='06/04/95', item_class=35, store=250\ndept=1, date='06/04/95', item_class=50, store=200\ndept=1, date='06/04/95', item_class=50, store=250\n\nThere are 2400 such accesses in total after transformation -- imagine\nadditional lines like these, for every distinct combination of dept\nand date (only for those dates that actually had sales, which they\nenumerate up-front), for store 200 and 250, and item_class 20, 35, and\n50. This adds up to 2400 lines in total. Even 2400 index probes will\nbe much faster than a full table scan, given that this is a large fact\ntable. The \"sales\" table is a clustered index whose keys are on the\ncolumns \"(dept, date, item_class, store)\", per note at the top of page\n4. The whole point is to avoid having any secondary indexes on this\nfact table, without getting a full scan. We can just probe the primary\nkey 2400 times instead, following this transformation. No need for\nsecondary indexes.\n\nThe plan can be thought of as a DAG, at least informally. This is also\nsomewhat similar to what Tom was thinking about back in 2018. Tom had\nto deduplicate rows during execution (IIRC using a UNION style ad-hoc\napproach that sorted on TIDs), whereas I think that they can get away\nwith skipping that extra step. Page 7 says \"MDAM removes duplicates\nbefore reading the data, so it does not have to do any post read\noperations to accomplish duplicate elimination (a common problem with\nOR optimization)\".\n\nMy general concern is that the skip scan patch may currently be\nstructured in a way that paints us into a corner, MDAM-wise.\n\nNote that the MDAM paper treats skipping a prefix of columns as a case\nwhere the prefix is handled by pretending that there is a clause that\nlooks like this: \"WHERE date between -inf AND +inf\" -- which is not so\ndifferent from the original sales SQL query example that I have\nhighlighted. We don't tend to think of queries like this (like my\nsales query) as in any way related to skip-scan, because we don't\nimagine that there is any skipping going on. But maybe we should\nrecognize the similarities.\n\nBTW, these imaginary -inf/+inf values seem to me to be just like the\nsentinel values already used inside nbtree, for pivot tuples -- they\nhave explicit -inf values for truncated suffix key columns, and you\ncan think of a rightmost page as having a +inf high key, per the L&Y\npaper. Wearing my B-Tree hat, I don't see much difference between\nimaginary -inf/+inf values, and values from the BETWEEN \"date\" range\nfrom the example SQL query. I have in the past wondered if\n_bt_get_endpoint() should have been implemented that way -- we could\ngo through _bt_search() instead, and get rid of that code. All we need\nis insertion scan keys that can explicitly contain the same -inf/+inf\nsentinel values. Maybe this also allows us to get rid of\nBTScanInsertData.nextkey semantics (not sure offhand).\n\nAnother more concrete concern about the patch series comes from the\nbackwards scan stuff. This is added by a later patch in the patch\nseries, \"v39-0004-Extend-amskip-implementation-for-Btree.patch\". It\nstrikes me as a bad thing that we cannot just do leaf-page-at-a-time\nprocessing, without usually needing to hold a pin on the leaf page.\nAfter all, ordinary backwards scans manage to avoid that today, albeit\nby using trickery inside _bt_walk_left(). MDAM-style \"Maintenance of\nIndex Order\" (as described on page 8) seems like a good goal for us\nhere. I don't like the idea of doing ad-hoc duplicate TID elimination\ninside nbtree, across calls made from the executor (whether it's\nduring backwards skip scans, or at any other time). Not because it\nseems to go against the approach taken by the MDAM paper (though it\ndoes); just because it seems kludgy. (I think that Tom felt the same\nway about the TID deduplication stuff in his own patch back in 2018,\ntoo.)\n\nOpen question: What does all of this MDAM business mean for\nScalarArrayOpExpr, if anything?\n\nI freely admit that I could easily be worrying over nothing here. But\nif I am, I'd really like to know *why* that's the case.\n\n[1] http://vldb.org/conf/1995/P710.PDF\n[2] https://blog.timescale.com/blog/how-we-made-distinct-queries-up-to-8000x-faster-on-postgresql/\n[3] https://www.postgresql.org/message-id/flat/7f70bd5a-5d16-e05c-f0b4-2fdfc8873489%40BlueTreble.com\n[4] https://www.postgresql.org/message-id/flat/14593.1517581614%40sss.pgh.pa.us#caf373b36332f25acb7673bff331c95e\n--\nPeter Geoghegan\n\n\n","msg_date":"Thu, 21 Oct 2021 19:16:00 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":true,"msg_subject":"MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Great to see some interest in the skip scan patch series again!\r\n\r\n> Like many difficult patches, the skip scan patch is not so much troubled by\r\n> problems with the implementation as it is troubled by\r\n> *ambiguity* about the design. Particularly concerning how skip scan meshes\r\n> with existing designs, as well as future designs -- particularly designs for\r\n> other MDAM techniques. I've started this thread to have a big picture\r\n> conversation about how to think about these things. Many other MDAM\r\n> techniques also seem highly appealing.\r\n\r\nI think it is good to have this discussion. In my opinion, Postgres could make really good use of some of the described MDAM techniques.\r\n\r\n> Much of the MDAM stuff is for data warehousing use-cases, while skip\r\n> scan/loose index scan is seen as more of an OLTP thing. But they are still\r\n> related, clearly.\r\n\r\nFWIW I think skip scan is very much data warehousing use-case related - hence why the TimescaleDb people in your [2] reference implemented a simple form of it already for their extension. Skip scan is a really useful feature for large data sets. However, I agree it is only one part of the bigger MDAM picture.\r\n\r\n> \r\n> My general concern is that the skip scan patch may currently be structured in\r\n> a way that paints us into a corner, MDAM-wise.\r\n> \r\n\r\nOne of the concerns I raised before was that the patch may be thinking too simplistically on some things, that would make it difficult to adopt more complex optimizations in the future. One concrete example can be illustrated by a different query on the sales table of the paper's example:\r\n\r\nSELECT DISTINCT dept, date WHERE item_class = 100\r\n\r\nThis should skip with prefix of (dept, date). Suppose we're at (dept, date) = (1, 2021-01-01) and it's skipping to the next prefix, the patch just implements what the MDAM paper describes as the 'probing' step. It finds the beginning of the next prefix. This could be for example (dept, date, item_class) = (1, 2021-01-02, 1). From there onwards, it would just scan the index until it finds item_class=100. What it should do however, is to first 'probe' for the next prefix value and then skip directly to (1, 2021-01-02, 100) (skipping item_class 1-99 altogether). The problem if it doesn't support this is that skip scan could have a quite unpredictable performance, because sometimes it'll end up going through most of the index where it should be skipping.\r\n\r\nA while ago, I spent quite some time trying to come up with an implementation that would work in this more general case. The nice thing is that with such a more generic implementation, you get almost all the features from the MDAM paper almost for free. I focused on the executor code, not on the planner code - the planner code is for the DISTINCT skip part very similar to the original patch and I hacked in a way to make it choose a 'skip scan' also for non-DISTINCT queries for testing purposes. For this discussion about MDAM, the planner part is less relevant though. There's still a lot of discussion and work on the planner-side too, but I think that is completely independent from each other.\r\n\r\nThe more generic patch I originally posted in [1], together with some technical considerations. That was quite a while ago so it obviously doesn't apply anymore on master. Therefore, I've attached a rebased version. Unfortunately, it's still based on an older version of the UniqueKeys patch - but since that patch is all planner machinery as well, it doesn't matter so much for the discussion about the executor code either.\r\n\r\nI believe if we want something that fits better with future MDAM use cases, we should take a closer look at the executor code of this patch to drive this discussion. The logic is definitely more complex than the original patch, however I believe it is also more flexible and future-proof.\r\n\r\n> \r\n> Another more concrete concern about the patch series comes from the\r\n> backwards scan stuff. This is added by a later patch in the patch series, \"v39-\r\n> 0004-Extend-amskip-implementation-for-Btree.patch\". It strikes me as a bad\r\n> thing that we cannot just do leaf-page-at-a-time processing, without usually\r\n> needing to hold a pin on the leaf page.\r\n> After all, ordinary backwards scans manage to avoid that today, albeit by\r\n> using trickery inside _bt_walk_left(). MDAM-style \"Maintenance of Index\r\n> Order\" (as described on page 8) seems like a good goal for us here. I don't\r\n> like the idea of doing ad-hoc duplicate TID elimination inside nbtree, across\r\n> calls made from the executor (whether it's during backwards skip scans, or at\r\n> any other time). Not because it seems to go against the approach taken by\r\n> the MDAM paper (though it does); just because it seems kludgy. (I think that\r\n> Tom felt the same way about the TID deduplication stuff in his own patch\r\n> back in 2018,\r\n> too.)\r\n\r\nIt's good to mention that the patch I attached does proper 'leaf-page-at-a-time' processing, so it avoids the problem you describe with v39. It is implemented instead in the same way as a \"regular\" index scan - we process the full leaf page and store the matched tuples in the local state. If a DISTINCT scan wants to do a skip, we check our local state first if that skipping would be possible with the matched tuples from the current page. Then we avoid double work and also the need to look at the same page again.\r\n\r\n> Open question: What does all of this MDAM business mean for\r\n> ScalarArrayOpExpr, if anything?\r\n> \r\n\r\nThis is a really interesting combination actually. I think, ideally, you'd probably get rid of it and provide full support for that with the 'skip' based approach (essentially the ScalarArrayOpExpr seems to do some form of skipping already - it transforms x IN (1,2,3) into 3 separate index scans for x).\r\nHowever, even without doing any work on it, it actually interacts nicely with the skip based approach.\r\n\r\nAs an example, here's some queries based on the 'sales' table of the paper with some data in it (18M rows total, see sales_query.sql attachment for the full example):\r\n\r\n-- terminology from paper: \"intervening range predicate\"\r\nselect date, sum(total_sales)\r\nfrom sales\r\nwhere dept between 2 and 3 and date between '2021-01-05' and '2021-01-10' and item_class=20 and store=250\r\ngroup by dept, date\r\n;\r\nPatch: Execution Time: 0.368 ms\r\nMaster: Execution Time: 416.792 ms\r\n\r\n-- terminology from paper: \"missing key predicate\"\r\nselect date, sum(total_sales)\r\nfrom sales\r\nwhere date between '2021-01-05' and '2021-01-10' and item_class=20 and store=250\r\ngroup by dept, date\r\n;\r\nPatch: Execution Time: 0.667 ms\r\nMaster: Execution Time: 654.684 ms\r\n\r\n-- terminology from paper: \"IN lists\" \r\n-- this is similar to the query from your example with an IN list\r\n-- in the current patch, this query is done with a skip scan with skip prefix (dept, date) and then the ScalarOpArray for item_class=(20,30,50)\r\nselect date, sum(total_sales)\r\nfrom sales\r\nwhere date between '2021-01-05' and '2021-01-10' and item_class in (20, 30, 50) and store=250\r\ngroup by dept, date\r\n;\r\nPatch: Execution Time: 1.767 ms\r\nMaster: Execution Time: 629.792 ms\r\n\r\nThe other mentioned MDAM optimizations in the paper (NOT =, general OR) are not implemented but don't seem to be conflicting at all with the current implementation - they seem to be just a matter of transforming the expressions into the right form.\r\n\r\nFrom the patch series above, v9-0001/v9-0002 is the UniqueKeys patch series, which focuses on the planner. v2-0001 is Dmitry's patch that extends it to make it possible to use UniqueKeys for the skip scan. Both of these are unfortunately still older patches, but because they are planner machinery they are less relevant to the discussion about the executor here.\r\nPatch v2-0002 contains most of my work and introduces all the executor logic for the skip scan and hooks up the planner for DISTINCT queries to use the skip scan.\r\nPatch v2-0003 is a planner hack that makes the planner pick a skip scan on virtually every possibility. This also enables the skip scan on the queries above that don't have a DISTINCT but where it could be useful.\r\n\r\n\r\n-Floris\r\n\r\n[1] https://www.postgresql.org/message-id/c5c5c974714a47f1b226c857699e8680@opammb0561.comp.optiver.com","msg_date":"Sat, 23 Oct 2021 19:30:47 +0000","msg_from":"Floris Van Nee <florisvannee@Optiver.com>","msg_from_op":false,"msg_subject":"RE: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Thu, Oct 21, 2021 at 07:16:00PM -0700, Peter Geoghegan wrote:\n>\n> My general concern is that the skip scan patch may currently be\n> structured in a way that paints us into a corner, MDAM-wise.\n>\n> Note that the MDAM paper treats skipping a prefix of columns as a case\n> where the prefix is handled by pretending that there is a clause that\n> looks like this: \"WHERE date between -inf AND +inf\" -- which is not so\n> different from the original sales SQL query example that I have\n> highlighted. We don't tend to think of queries like this (like my\n> sales query) as in any way related to skip-scan, because we don't\n> imagine that there is any skipping going on. But maybe we should\n> recognize the similarities.\n\nTo avoid potential problems with extensibility in this sense, the\nimplementation needs to explicitly work with sets of disjoint intervals\nof values instead of simple prefix size, one set of intervals per scan\nkey. An interesting idea, doesn't seem to be a big change in terms of\nthe patch itself.\n\n\n","msg_date":"Sun, 24 Oct 2021 04:44:01 +0200","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Hi Peter,\n\nOn 10/21/21 22:16, Peter Geoghegan wrote:\n> I returned to the 1995 paper \"Efficient Search of Multidimensional\n> B-Trees\" [1] as part of the process of reviewing v39 of the skip scan\n> patch, which was posted back in May. It's a great paper, and anybody\n> involved in the skip scan effort should read it thoroughly (if they\n> haven't already). It's easy to see why people get excited about skip\n> scan [2]. But there is a bigger picture here.\n> \n\nThanks for starting this thread !\n\nThe Index Skip Scan patch could affect a lot of areas, so keeping MDAM \nin mind is definitely important.\n\nHowever, I think the key part to progress on the \"core\" functionality \n(B-tree related changes) is to get the planner functionality in place \nfirst. Hopefully we can make progress on that during the November \nCommitFest based on Andy's patch.\n\nBest regards,\n Jesper\n\n\n\n","msg_date":"Mon, 25 Oct 2021 08:10:56 -0400","msg_from":"Jesper Pedersen <jesper.pedersen@redhat.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Hi,\n\nOn Sat, Oct 23, 2021 at 07:30:47PM +0000, Floris Van Nee wrote:\n> \n> From the patch series above, v9-0001/v9-0002 is the UniqueKeys patch series,\n> which focuses on the planner. v2-0001 is Dmitry's patch that extends it to\n> make it possible to use UniqueKeys for the skip scan. Both of these are\n> unfortunately still older patches, but because they are planner machinery\n> they are less relevant to the discussion about the executor here. Patch\n> v2-0002 contains most of my work and introduces all the executor logic for\n> the skip scan and hooks up the planner for DISTINCT queries to use the skip\n> scan. Patch v2-0003 is a planner hack that makes the planner pick a skip\n> scan on virtually every possibility. This also enables the skip scan on the\n> queries above that don't have a DISTINCT but where it could be useful.\n\nThe patchset doesn't apply anymore:\nhttp://cfbot.cputube.org/patch_36_1741.log\n=== Applying patches on top of PostgreSQL commit ID a18b6d2dc288dfa6e7905ede1d4462edd6a8af47 ===\n=== applying patch ./v2-0001-Extend-UniqueKeys.patch\n[...]\npatching file src/include/optimizer/paths.h\nHunk #2 FAILED at 299.\n1 out of 2 hunks FAILED -- saving rejects to file src/include/optimizer/paths.h.rej\n\nCould you send a rebased version? In the meantime I will change the status on\nthe cf app to Waiting on Author.\n\n\n","msg_date":"Thu, 13 Jan 2022 18:36:12 +0800","msg_from":"Julien Rouhaud <rjuju123@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> \n> Could you send a rebased version? In the meantime I will change the status\n> on the cf app to Waiting on Author.\n\nAttached a rebased version.","msg_date":"Thu, 13 Jan 2022 15:27:08 +0000","msg_from":"Floris Van Nee <florisvannee@Optiver.com>","msg_from_op":false,"msg_subject":"RE: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Thu, Jan 13, 2022 at 03:27:08PM +0000, Floris Van Nee wrote:\n> >\n> > Could you send a rebased version? In the meantime I will change the status\n> > on the cf app to Waiting on Author.\n>\n> Attached a rebased version.\n\nFYI, I've attached this thread to the CF item as an informational one,\nbut as there are some patches posted here, folks may get confused. For\nthose who have landed here with no context, I feel obliged to mention\nthat now there are two alternative patch series posted under the same\nCF item:\n\n* the original one lives in [1], waiting for reviews since the last May\n* an alternative one posted here from Floris\n\n[1]: https://www.postgresql.org/message-id/flat/20200609102247.jdlatmfyeecg52fi@localhost\n\n\n","msg_date":"Fri, 14 Jan 2022 08:55:26 +0100","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Hi,\n\nOn Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\n> \n> FYI, I've attached this thread to the CF item as an informational one,\n> but as there are some patches posted here, folks may get confused. For\n> those who have landed here with no context, I feel obliged to mention\n> that now there are two alternative patch series posted under the same\n> CF item:\n> \n> * the original one lives in [1], waiting for reviews since the last May\n> * an alternative one posted here from Floris\n\nAh, I indeed wasn't sure of which patchset(s) should actually be reviewed.\nIt's nice to have the alternative approach threads linkied in the commit fest,\nbut it seems that the cfbot will use the most recent attachments as the only\npatchset, thus leaving the \"original\" one untested.\n\nI'm not sure of what's the best approach in such situation. Maybe creating a\ndifferent CF entry for each alternative, and link the other cf entry on the cf\napp using the \"Add annotations\" or \"Links\" feature rather than attaching\nthreads?\n\n\n","msg_date":"Fri, 14 Jan 2022 16:03:41 +0800","msg_from":"Julien Rouhaud <rjuju123@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Fri, Jan 14, 2022 at 04:03:41PM +0800, Julien Rouhaud wrote:\n> Hi,\n>\n> On Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\n> >\n> > FYI, I've attached this thread to the CF item as an informational one,\n> > but as there are some patches posted here, folks may get confused. For\n> > those who have landed here with no context, I feel obliged to mention\n> > that now there are two alternative patch series posted under the same\n> > CF item:\n> >\n> > * the original one lives in [1], waiting for reviews since the last May\n> > * an alternative one posted here from Floris\n>\n> Ah, I indeed wasn't sure of which patchset(s) should actually be reviewed.\n> It's nice to have the alternative approach threads linkied in the commit fest,\n> but it seems that the cfbot will use the most recent attachments as the only\n> patchset, thus leaving the \"original\" one untested.\n>\n> I'm not sure of what's the best approach in such situation. Maybe creating a\n> different CF entry for each alternative, and link the other cf entry on the cf\n> app using the \"Add annotations\" or \"Links\" feature rather than attaching\n> threads?\n\nI don't mind having all of the alternatives under the same CF item, only\none being tested seems to be only a small limitation of cfbot.\n\n\n","msg_date":"Sat, 22 Jan 2022 22:37:19 +0100","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Hi,\n\nOn 2022-01-22 22:37:19 +0100, Dmitry Dolgov wrote:\n> > On Fri, Jan 14, 2022 at 04:03:41PM +0800, Julien Rouhaud wrote:\n> > Hi,\n> >\n> > On Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\n> > >\n> > > FYI, I've attached this thread to the CF item as an informational one,\n> > > but as there are some patches posted here, folks may get confused. For\n> > > those who have landed here with no context, I feel obliged to mention\n> > > that now there are two alternative patch series posted under the same\n> > > CF item:\n> > >\n> > > * the original one lives in [1], waiting for reviews since the last May\n> > > * an alternative one posted here from Floris\n> >\n> > Ah, I indeed wasn't sure of which patchset(s) should actually be reviewed.\n> > It's nice to have the alternative approach threads linkied in the commit fest,\n> > but it seems that the cfbot will use the most recent attachments as the only\n> > patchset, thus leaving the \"original\" one untested.\n> >\n> > I'm not sure of what's the best approach in such situation. Maybe creating a\n> > different CF entry for each alternative, and link the other cf entry on the cf\n> > app using the \"Add annotations\" or \"Links\" feature rather than attaching\n> > threads?\n> \n> I don't mind having all of the alternatives under the same CF item, only\n> one being tested seems to be only a small limitation of cfbot.\n\nIMO it's pretty clear that having \"duelling\" patches below one CF entry is a\nbad idea. I think they should be split, with inactive approaches marked as\nreturned with feeback or whatnot.\n\nEither way, currently this patch fails on cfbot due to a new GUC:\nhttps://api.cirrus-ci.com/v1/artifact/task/5134905372835840/log/src/test/recovery/tmp_check/regression.diffs\nhttps://cirrus-ci.com/task/5134905372835840\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 21 Mar 2022 18:34:09 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Mon, Mar 21, 2022 at 06:34:09PM -0700, Andres Freund wrote:\n>\n> > I don't mind having all of the alternatives under the same CF item, only\n> > one being tested seems to be only a small limitation of cfbot.\n>\n> IMO it's pretty clear that having \"duelling\" patches below one CF entry is a\n> bad idea. I think they should be split, with inactive approaches marked as\n> returned with feeback or whatnot.\n\nOn the other hand even for patches with dependencies (i.e. the patch A\ndepends on the patch B) different CF items cause a lot of confusion for\nreviewers. I guess for various flavours of the same patch it would be\neven worse. But I don't have a strong opinion here.\n\n> Either way, currently this patch fails on cfbot due to a new GUC:\n> https://api.cirrus-ci.com/v1/artifact/task/5134905372835840/log/src/test/recovery/tmp_check/regression.diffs\n> https://cirrus-ci.com/task/5134905372835840\n\nThis seems to be easy to solve.","msg_date":"Tue, 22 Mar 2022 21:00:08 +0100","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On Tue, Mar 22, 2022 at 2:34 PM Andres Freund <andres@anarazel.de> wrote:\n> IMO it's pretty clear that having \"duelling\" patches below one CF entry is a\n> bad idea. I think they should be split, with inactive approaches marked as\n> returned with feeback or whatnot.\n\nI have the impression that this thread is getting some value from\nhaving a CF entry, as a multi-person collaboration where people are\ntrading ideas and also making progress that no one wants to mark as\nreturned, but it's vexing for people managing the CF because it's not\nreally proposed for 15. Perhaps what we lack is a new status, \"Work\nIn Progress\" or something?\n\n\n","msg_date":"Wed, 23 Mar 2022 09:33:50 +1300","msg_from":"Thomas Munro <thomas.munro@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Peter Geoghegan <pg@bowt.ie> writes:\n> Like many difficult patches, the skip scan patch is not so much\n> troubled by problems with the implementation as it is troubled by\n> *ambiguity* about the design. Particularly concerning how skip scan\n> meshes with existing designs, as well as future designs --\n> particularly designs for other MDAM techniques. I've started this\n> thread to have a big picture conversation about how to think about\n> these things.\n\nPeter asked me off-list to spend some time thinking about the overall\ndirection we ought to be pursuing here. I have done that, and here\nare a few modest suggestions.\n\n1. Usually I'm in favor of doing this sort of thing in an index AM\nagnostic way, but here I don't see much point. All of the ideas at\nstake rely fundamentally on having a lexicographically-ordered multi\ncolumn index; but we don't have any of those except btree, nor do\nI think we're likely to get any soon. This motivates the general\ntenor of my remarks below, which is \"do it in access/nbtree/ not in\nthe planner\".\n\n2. The MDAM paper Peter cited is really interesting. You can see\nfragments of those ideas in our existing btree code, particularly in\nthe scan setup stuff that detects redundant or contradictory keys and\ndetermines a scan start strategy. The special handling we implemented\nawhile ago for ScalarArrayOp index quals is also a subset of what they\nwere talking about. It seems to me that if we wanted to implement more\nof those ideas, the relevant work should almost all be done in nbtree\nproper. The planner would need only minor adjustments: btcostestimate\nwould have to be fixed to understand the improvements, and there are\nsome rules in indxpath.c that prevent us from passing \"too complicated\"\nsets of indexquals to the AM, which would need to be relaxed or removed\naltogether.\n\n3. \"Loose\" indexscan (i.e., sometimes re-descend from the tree root\nto find the next index entry) is again something that seems like it's\nmainly nbtree's internal problem. Loose scan is interesting if we\nhave index quals for columns that are after the first column that lacks\nan equality qual, otherwise not. I've worried in the past that we'd\nneed planner/statistical support to figure out whether a loose scan\nis likely to be useful compared to just plowing ahead in the index.\nHowever, that seems to be rendered moot by the idea used in the current\npatchsets, ie scan till we find that we'll have to step off the current\npage, and re-descend at that point. (When and if we find that that\nheuristic is inadequate, we could work on passing some statistical data\nforward. But we don't need any in the v1 patch.) Again, we need some\nwork in btcostestimate to understand how the index scan cost will be\naffected, but I still don't see any pressing need for major planner\nchanges or plan tree contents changes.\n\n4. I find each of the above ideas to be far more attractive than\noptimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\nunderstand why the current patchsets seem to be driven largely\nby that single use-case. I wouldn't even bother with that for the\ninitial patch. When we do get around to it, it still doesn't need\nmajor planner support, I think --- again fixing the cost estimation\nis the bulk of the work. Munro's original 2014 patch showed that we\ndon't really need all that much to get the planner to build such a\nplan; the problem is to convince it that that plan will be cheap.\n\nIn short: I would throw out just about all the planner infrastructure\nthat's been proposed so far. It looks bulky, expensive, and\ndrastically undercommented, and I don't think it's buying us anything\nof commensurate value. The part of the planner that actually needs\nserious thought is btcostestimate, which has been woefully neglected in\nboth of the current patchsets.\n\nBTW, I've had a bee in my bonnet for a long time about whether some of\nnbtree's scan setup work could be done once during planning, rather than\nover again during each indexscan start. This issue might become more\npressing if the work becomes significantly more complicated/expensive,\nwhich these ideas might cause. But it's a refinement that could be\nleft for later --- and in any case, the responsibility would still\nfundamentally be nbtree's. I don't think the planner would do more\nthan call some AM routine that could add decoration to an IndexScan\nplan node.\n\nNow ... where did I put my flameproof vest?\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 22 Mar 2022 16:55:49 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Hi,\n\nOn 2022-03-22 16:55:49 -0400, Tom Lane wrote:\n> 4. I find each of the above ideas to be far more attractive than\n> optimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\n> understand why the current patchsets seem to be driven largely\n> by that single use-case.\n\nIt's something causing plenty pain in production environments... Obviously\nit'd be even better if the optimization also triggered in cases like\n SELECT some_indexed_col FROM blarg GROUP BY some_indexed_col\nwhich seems to be what ORMs like to generate.\n\n\n> BTW, I've had a bee in my bonnet for a long time about whether some of\n> nbtree's scan setup work could be done once during planning, rather than\n> over again during each indexscan start.\n\nIt does show up in simple-index-lookup heavy workloads. Not as a major thing,\nbut it's there. And it's just architecturally displeasing :)\n\nAre you thinking of just moving the setup stuff in nbtree (presumably parts of\n_bt_first() / _bt_preprocess_keys()) or also stuff in\nExecIndexBuildScanKeys()?\n\nThe latter does show up a bit more heavily in profiles than nbtree specific\nsetup, and given that it's generic executor type stuff, seems even more\namenable to being moved to plan time.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 22 Mar 2022 16:06:14 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2022-03-22 16:55:49 -0400, Tom Lane wrote:\n>> BTW, I've had a bee in my bonnet for a long time about whether some of\n>> nbtree's scan setup work could be done once during planning, rather than\n>> over again during each indexscan start.\n\n> It does show up in simple-index-lookup heavy workloads. Not as a major thing,\n> but it's there. And it's just architecturally displeasing :)\n> Are you thinking of just moving the setup stuff in nbtree (presumably parts of\n> _bt_first() / _bt_preprocess_keys()) or also stuff in\n> ExecIndexBuildScanKeys()?\n\nDidn't really have specifics in mind. The key stumbling block is\nthat some (not all) of the work depends on knowing the specific\nvalues of the indexqual comparison keys, so while you could do\nthat work in advance for constant keys, you'd still have to be\nprepared to do work at scan start for non-constant keys. I don't\nhave a clear idea about how to factorize that effectively.\n\nA couple of other random ideas in this space:\n\n* I suspect that a lot of this work overlaps with the efforts that\nbtcostestimate makes along the way to getting a cost estimate.\nSo it's interesting to wonder whether we could refactor so that\nbtcostestimate is integrated with this hypothetical plan-time key\npreprocessing and doesn't duplicate work.\n\n* I think that we run through most or all of that preprocessing\nlogic even for internal catalog accesses, where we know darn well\nhow the keys are set up. We ought to think harder about how we\ncould short-circuit pointless work in those code paths.\n\nI don't think any of this is an essential prerequisite to getting\nsomething done for loose index scans, which ISTM ought to be the first\npoint of attack for v16. Loose index scans per se shouldn't add much\nto the key preprocessing costs. But these ideas likely would be\nuseful to look into before anyone starts on the more complicated\npreprocessing that would be needed for the ideas in the MDAM paper.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 22 Mar 2022 19:34:52 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\n> Peter Geoghegan <pg@bowt.ie> writes:\n> > Like many difficult patches, the skip scan patch is not so much\n> > troubled by problems with the implementation as it is troubled by\n> > *ambiguity* about the design. Particularly concerning how skip scan\n> > meshes with existing designs, as well as future designs --\n> > particularly designs for other MDAM techniques. I've started this\n> > thread to have a big picture conversation about how to think about\n> > these things.\n>\n> Peter asked me off-list to spend some time thinking about the overall\n> direction we ought to be pursuing here. I have done that, and here\n> are a few modest suggestions.\n\nThanks. To make sure I understand your proposal better, I have a couple\nof questions:\n\n> In short: I would throw out just about all the planner infrastructure\n> that's been proposed so far. It looks bulky, expensive, and\n> drastically undercommented, and I don't think it's buying us anything\n> of commensurate value.\n\nBroadly speaking planner related changes proposed in the patch so far\nare: UniqueKey, taken from the neighbour thread about select distinct;\nlist of uniquekeys to actually pass information about the specified\nloose scan prefix into nbtree; some verification logic to prevent\napplying skipping when it's not supported. I can imagine taking out\nUniqueKeys and passing loose scan prefix in some other form (the other\nparts seems to be essential) -- is that what you mean?\n\n\n","msg_date":"Wed, 23 Mar 2022 21:47:47 +0100","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Dmitry Dolgov <9erthalion6@gmail.com> writes:\n> On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\n>> In short: I would throw out just about all the planner infrastructure\n>> that's been proposed so far. It looks bulky, expensive, and\n>> drastically undercommented, and I don't think it's buying us anything\n>> of commensurate value.\n\n> Broadly speaking planner related changes proposed in the patch so far\n> are: UniqueKey, taken from the neighbour thread about select distinct;\n> list of uniquekeys to actually pass information about the specified\n> loose scan prefix into nbtree; some verification logic to prevent\n> applying skipping when it's not supported. I can imagine taking out\n> UniqueKeys and passing loose scan prefix in some other form (the other\n> parts seems to be essential) -- is that what you mean?\n\nMy point is that for pure loose scans --- that is, just optimizing a scan,\nnot doing AM-based duplicate-row-elimination --- you do not need to pass\nany new data to btree at all. It can infer what to do on the basis of the\nset of index quals it's handed.\n\nThe bigger picture here is that I think the reason this patch series has\nfailed to progress is that it's too scattershot. You need to pick a\nminimum committable feature and get that done, and then you can move on\nto the next part. I think the minimum committable feature is loose scans,\nwhich will require a fair amount of work in access/nbtree/ but very little\nnew planner code, and will be highly useful in their own right even if we\nnever do anything more.\n\nIn general I feel that the UniqueKey code is a solution looking for a\nproblem, and that treating it as the core of the patchset is a mistake.\nWe should be driving this work off of what nbtree needs to make progress,\nand not building more infrastructure elsewhere than we have to. Maybe\nwe'll end up with something that looks like UniqueKeys, but I'm far from\nconvinced of that.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 23 Mar 2022 17:32:46 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"> On Wed, Mar 23, 2022 at 05:32:46PM -0400, Tom Lane wrote:\n> Dmitry Dolgov <9erthalion6@gmail.com> writes:\n> > On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\n> >> In short: I would throw out just about all the planner infrastructure\n> >> that's been proposed so far. It looks bulky, expensive, and\n> >> drastically undercommented, and I don't think it's buying us anything\n> >> of commensurate value.\n>\n> > Broadly speaking planner related changes proposed in the patch so far\n> > are: UniqueKey, taken from the neighbour thread about select distinct;\n> > list of uniquekeys to actually pass information about the specified\n> > loose scan prefix into nbtree; some verification logic to prevent\n> > applying skipping when it's not supported. I can imagine taking out\n> > UniqueKeys and passing loose scan prefix in some other form (the other\n> > parts seems to be essential) -- is that what you mean?\n>\n> My point is that for pure loose scans --- that is, just optimizing a scan,\n> not doing AM-based duplicate-row-elimination --- you do not need to pass\n> any new data to btree at all. It can infer what to do on the basis of the\n> set of index quals it's handed.\n>\n> The bigger picture here is that I think the reason this patch series has\n> failed to progress is that it's too scattershot. You need to pick a\n> minimum committable feature and get that done, and then you can move on\n> to the next part. I think the minimum committable feature is loose scans,\n> which will require a fair amount of work in access/nbtree/ but very little\n> new planner code, and will be highly useful in their own right even if we\n> never do anything more.\n>\n> In general I feel that the UniqueKey code is a solution looking for a\n> problem, and that treating it as the core of the patchset is a mistake.\n> We should be driving this work off of what nbtree needs to make progress,\n> and not building more infrastructure elsewhere than we have to. Maybe\n> we'll end up with something that looks like UniqueKeys, but I'm far from\n> convinced of that.\n\nI see. I'll need some thinking time about how it may look like (will\nprobably return with more questions).\n\nThe CF item could be set to RwF, what would you say, Jesper?\n\n\n","msg_date":"Wed, 23 Mar 2022 23:22:32 +0100","msg_from":"Dmitry Dolgov <9erthalion6@gmail.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On 3/23/22 18:22, Dmitry Dolgov wrote:\n> \n> The CF item could be set to RwF, what would you say, Jesper?\n> \n\nWe want to thank the community for the feedback that we have received \nover the years for this feature. Hopefully a future implementation can \nuse Tom's suggestions to get closer to a committable solution.\n\nHere is the last CommitFest entry [1] for the archives.\n\nRwF\n\n[1] https://commitfest.postgresql.org/37/1741/\n\nBest regards,\n Dmitry & Jesper\n\n\n\n","msg_date":"Thu, 24 Mar 2022 07:32:14 -0400","msg_from":"Jesper Pedersen <jesper.pedersen@redhat.com>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On Tue, Mar 22, 2022 at 4:06 PM Andres Freund <andres@anarazel.de> wrote:\n> Are you thinking of just moving the setup stuff in nbtree (presumably parts of\n> _bt_first() / _bt_preprocess_keys()) or also stuff in\n> ExecIndexBuildScanKeys()?\n>\n> The latter does show up a bit more heavily in profiles than nbtree specific\n> setup, and given that it's generic executor type stuff, seems even more\n> amenable to being moved to plan time.\n\nWhen I was working on the patch series that became the nbtree Postgres\n12 work, this came up. At one point I discovered that using palloc0()\nfor the insertion scankey in _bt_first() was a big problem with nested\nloop joins -- it became a really noticeable bottleneck with one of my\ntest cases. I independently discovered what Tom must have figured out\nback in 2005, when he committed d961a56899. This led to my making the\nnew insertion scan key structure (BTScanInsertData) not use dynamic\nallocation. So _bt_first() is definitely performance critical for\ncertain types of queries.\n\nWe could get rid of dynamic allocations for BTStackData in\n_bt_first(), perhaps. The problem is that there is no simple,\nreasonable proof of the maximum height on a B-tree, even though a\nB-Tree with more than 7 or 8 levels seems extraordinarily unlikely.\nYou could also invent a slow path (maybe do what we do in\n_bt_insert_parent() in the event of a concurrent root page split/NULL\nstack), but that runs into the problem of being awkward to test, and\npretty ugly. It's doable, but I wouldn't do it unless there was a\npretty noticeable payoff.\n\n-- \nPeter Geoghegan\n\n\n","msg_date":"Mon, 28 Mar 2022 17:13:16 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":true,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Peter Geoghegan <pg@bowt.ie> writes:\n> We could get rid of dynamic allocations for BTStackData in\n> _bt_first(), perhaps. The problem is that there is no simple,\n> reasonable proof of the maximum height on a B-tree, even though a\n> B-Tree with more than 7 or 8 levels seems extraordinarily unlikely.\n\nStart with a few entries preallocated, and switch to dynamically\nallocated space if there turn out to be more levels than that,\nperhaps? Not sure if it's worth the trouble.\n\nIn any case, what I was on about is _bt_preprocess_keys() and\nadjacent code. I'm surprised that those aren't more expensive\nthan one palloc in _bt_first. Maybe that logic falls through very\nquickly in simple cases, though.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 28 Mar 2022 20:21:54 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On Tue, Mar 22, 2022 at 1:55 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Peter asked me off-list to spend some time thinking about the overall\n> direction we ought to be pursuing here.\n\nThanks for taking a look!\n\n\"5.5 Exploiting Key Prefixes\" and \"5.6 Ordered Retrieval\" from \"Modern\nB-Tree Techniques\" are also good, BTW.\n\nThe terminology in this area is a mess. MySQL calls\nSELECT-DISTINCT-that-matches-an-index \"loose index scans\". I think\nthat you're talking about skip scan when you say \"loose index scan\".\nSkip scan is where there is an omitted prefix of columns in the SQL\nquery -- omitted columns after the first column that lack an equality\nqual. Pretty sure that MySQL/InnoDB can't do that -- it can only\n\"skip\" to the extent required to make\nSELECT-DISTINCT-that-matches-an-index perform well, but that's about\nit.\n\nIt might be useful for somebody to go write a \"taxonomy of MDAM\ntechniques\", or a glossary. The existing \"Loose indexscan\" Postgres\nwiki page doesn't seem like enough. Something very high level and\nexplicit, with examples, just so we don't end up talking at cross\npurposes too much.\n\n> 1. Usually I'm in favor of doing this sort of thing in an index AM\n> agnostic way, but here I don't see much point. All of the ideas at\n> stake rely fundamentally on having a lexicographically-ordered multi\n> column index; but we don't have any of those except btree, nor do\n> I think we're likely to get any soon. This motivates the general\n> tenor of my remarks below, which is \"do it in access/nbtree/ not in\n> the planner\".\n\nThat was my intuition all along, but I didn't quite have the courage\nto say so -- sounds too much like something that an optimizer\ndilettante like me would be expected to say. :-)\n\nSeems like one of those things where lots of high level details\nintrinsically need to be figured out on-the-fly, at execution time,\nrather than during planning. Perhaps it'll be easier to correctly\ndetermine that a skip scan plan is the cheapest in practice than to\naccurately cost skip scan plans. If the only alternative is a\nsequential scan, then perhaps a very approximate cost model will work\nwell enough. It's probably way too early to tell right now, though.\n\n> I've worried in the past that we'd\n> need planner/statistical support to figure out whether a loose scan\n> is likely to be useful compared to just plowing ahead in the index.\n\nI don't expect to be able to come up with a structure that leaves no\nunanswered questions about future MDAM work -- it's not realistic to\nexpect everything to just fall into place. But that's okay. Just\nhaving everybody agree on roughly the right conceptual model is the\nreally important thing. That now seems quite close, which I count as\nreal progress.\n\n> 4. I find each of the above ideas to be far more attractive than\n> optimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\n> understand why the current patchsets seem to be driven largely\n> by that single use-case. I wouldn't even bother with that for the\n> initial patch.\n\nI absolutely agree. I wondered about that myself in the past. My best\nguess is that a certain segment of users are familiar with\nSELECT-DISTINCT-that-matches-an-index from MySQL. And so to some\nextent application frameworks evolved in a world where that capability\nexisted. IIRC Jesper once said that Hibernate relied on this\ncapability.\n\nIt's probably a lot easier to implement\nSELECT-DISTINCT-that-matches-an-index if you have the MySQL storage\nengine model, with concurrency control that's typically based on\ntwo-phase locking. I think that MySQL does some amount of\ndeduplication in its executor here -- and *not* in what they call the storage\nengine. This is exactly what I'd like to avoid in Postgres; as I said\n\"Maintenance of Index Order\" (as the paper calls it) seems important,\nand not something to be added later on. Optimizer and executor layers\nthat each barely know the difference between a skip scan and a full\nindex scan seems like something we might actually want to aim for,\nrather than avoid. Teaching nbtree to transform quals into ranges\nsounds odd at first, but it seems like the right approach now, on\nbalance -- that's the only *good* way to maintain index order.\n(Maintaining index order is needed to avoid needing or relying on\ndeduplication in the executor proper, which is even inappropriate in\nan implementation of SELECT-DISTINCT-that-matches-an-index IMO.)\n\n--\nPeter Geoghegan\n\n\n","msg_date":"Mon, 28 Mar 2022 18:58:22 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":true,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On Mon, Mar 28, 2022 at 5:21 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> In any case, what I was on about is _bt_preprocess_keys() and\n> adjacent code. I'm surprised that those aren't more expensive\n> than one palloc in _bt_first. Maybe that logic falls through very\n> quickly in simple cases, though.\n\nI assume that it doesn't really appear in very simple cases (also\ncommon cases). But delaying the scan setup work until execution time\ndoes seem ugly. That's probably a good enough reason to refactor.\n\n-- \nPeter Geoghegan\n\n\n","msg_date":"Mon, 28 Mar 2022 19:03:17 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":true,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"Peter Geoghegan <pg@bowt.ie> writes:\n> The terminology in this area is a mess. MySQL calls\n> SELECT-DISTINCT-that-matches-an-index \"loose index scans\". I think\n> that you're talking about skip scan when you say \"loose index scan\".\n> Skip scan is where there is an omitted prefix of columns in the SQL\n> query -- omitted columns after the first column that lack an equality\n> qual.\n\nRight, that's the case I had in mind --- apologies if my terminology\nwas faulty. btree can actually handle such a case now, but what it\nfails to do is re-descend from the tree root instead of plowing\nforward in the index to find the next matching entry.\n\n> It might be useful for somebody to go write a \"taxonomy of MDAM\n> techniques\", or a glossary.\n\n+1. We at least need to be sure we all are using these terms\nthe same way.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 28 Mar 2022 22:07:44 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"},{"msg_contents":"On Mon, Mar 28, 2022 at 7:07 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Right, that's the case I had in mind --- apologies if my terminology\n> was faulty. btree can actually handle such a case now, but what it\n> fails to do is re-descend from the tree root instead of plowing\n> forward in the index to find the next matching entry.\n\nKNNGIST seems vaguely related to what we'd build for nbtree skip scan,\nthough. GiST index scans are \"inherently loose\", though. KNNGIST uses\na pairing heap/priority queue, which seems like the kind of thing\nnbtree skip scan can avoid.\n\n> +1. We at least need to be sure we all are using these terms\n> the same way.\n\nYeah, there are *endless* opportunities for confusion here.\n\n-- \nPeter Geoghegan\n\n\n","msg_date":"Mon, 28 Mar 2022 20:19:15 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":true,"msg_subject":"Re: MDAM techniques and Index Skip Scan patch"}],"string":"[\n {\n \"msg_contents\": \"I returned to the 1995 paper \\\"Efficient Search of Multidimensional\\nB-Trees\\\" [1] as part of the process of reviewing v39 of the skip scan\\npatch, which was posted back in May. It's a great paper, and anybody\\ninvolved in the skip scan effort should read it thoroughly (if they\\nhaven't already). It's easy to see why people get excited about skip\\nscan [2]. But there is a bigger picture here.\\n\\nI don't necessarily expect to come away from this discussion with a\\nmuch better high level architecture for the patch, or any kind of\\ndeeper insight, or even a frame of reference for further discussion. I\\njust think that we ought to *try* to impose some order on this stuff.\\n\\nLike many difficult patches, the skip scan patch is not so much\\ntroubled by problems with the implementation as it is troubled by\\n*ambiguity* about the design. Particularly concerning how skip scan\\nmeshes with existing designs, as well as future designs --\\nparticularly designs for other MDAM techniques. I've started this\\nthread to have a big picture conversation about how to think about\\nthese things. Many other MDAM techniques also seem highly appealing.\\nMuch of the MDAM stuff is for data warehousing use-cases, while skip\\nscan/loose index scan is seen as more of an OLTP thing. But they are\\nstill related, clearly.\\n\\nI'd like to also talk about another patch, that ISTM had that same\\nquality -- it was also held back by high level design uncertainty. Back in 2018,\\nTom abandoned a patch that transformed a star-schema style query with\\nleft outer joins on dimension tables with OR conditions, into an\\nequivalent query that UNIONs together 2 distinct queries [3][4].\\n\\nBelieve it or not, I am now reminded of that patch by the example of\\n\\\"IN() Lists\\\", from page 5 of the paper. We see this example SQL query:\\n\\nSELECT date, item_class, store, sum(total_sales)\\nFROM sales\\nWHERE date between '06/01/95' and '06/30/95' and\\nitem_class IN (20,35,50) and\\nstore IN (200,250)\\nGROUP BY dept, date, item_class, store;\\n\\nGranted, this SQL might not seem directly relevant to Tom's patch at\\nfirst -- there is no join for the optimizer to even try to eliminate,\\nwhich was the whole basis of Jim Nasby's original complaint, which is\\nwhat spurred Tom to write the patch in the first place. But hear me\\nout: there is still a fact table (the sales table) with some\\ndimensions (the 'D' from 'MDAM') shown in the predicate. Moreover, the\\ntable (and this SQL query) drives discussion of an optimization\\ninvolving transforming a predicate with many ORs (which is explicitly\\nsaid to be logically/semantically equivalent to the IN() lists from\\nthe query). They transform the query into a bunch of disjunct clauses\\nthat can easily be independently executed, and combined at the end\\n(see also \\\"General OR Optimization\\\" on page 6 of the paper).\\n\\nAlso...I'm not entirely sure that the intended underlying \\\"physical\\nplan\\\" is truly free of join-like scans. If you squint just right, you\\nmight see something that you could think of as a \\\"physical join\\\" (at\\nleast very informally). The whole point of this particular \\\"IN()\\nLists\\\" example is that we get to the following, for each distinct\\n\\\"dept\\\" and \\\"date\\\" in the table:\\n\\ndept=1, date='06/04/95', item_class=20, store=200\\ndept=1, date='06/04/95', item_class=20, store=250\\ndept=1, date='06/04/95', item_class=35, store=200\\ndept=1, date='06/04/95', item_class=35, store=250\\ndept=1, date='06/04/95', item_class=50, store=200\\ndept=1, date='06/04/95', item_class=50, store=250\\n\\nThere are 2400 such accesses in total after transformation -- imagine\\nadditional lines like these, for every distinct combination of dept\\nand date (only for those dates that actually had sales, which they\\nenumerate up-front), for store 200 and 250, and item_class 20, 35, and\\n50. This adds up to 2400 lines in total. Even 2400 index probes will\\nbe much faster than a full table scan, given that this is a large fact\\ntable. The \\\"sales\\\" table is a clustered index whose keys are on the\\ncolumns \\\"(dept, date, item_class, store)\\\", per note at the top of page\\n4. The whole point is to avoid having any secondary indexes on this\\nfact table, without getting a full scan. We can just probe the primary\\nkey 2400 times instead, following this transformation. No need for\\nsecondary indexes.\\n\\nThe plan can be thought of as a DAG, at least informally. This is also\\nsomewhat similar to what Tom was thinking about back in 2018. Tom had\\nto deduplicate rows during execution (IIRC using a UNION style ad-hoc\\napproach that sorted on TIDs), whereas I think that they can get away\\nwith skipping that extra step. Page 7 says \\\"MDAM removes duplicates\\nbefore reading the data, so it does not have to do any post read\\noperations to accomplish duplicate elimination (a common problem with\\nOR optimization)\\\".\\n\\nMy general concern is that the skip scan patch may currently be\\nstructured in a way that paints us into a corner, MDAM-wise.\\n\\nNote that the MDAM paper treats skipping a prefix of columns as a case\\nwhere the prefix is handled by pretending that there is a clause that\\nlooks like this: \\\"WHERE date between -inf AND +inf\\\" -- which is not so\\ndifferent from the original sales SQL query example that I have\\nhighlighted. We don't tend to think of queries like this (like my\\nsales query) as in any way related to skip-scan, because we don't\\nimagine that there is any skipping going on. But maybe we should\\nrecognize the similarities.\\n\\nBTW, these imaginary -inf/+inf values seem to me to be just like the\\nsentinel values already used inside nbtree, for pivot tuples -- they\\nhave explicit -inf values for truncated suffix key columns, and you\\ncan think of a rightmost page as having a +inf high key, per the L&Y\\npaper. Wearing my B-Tree hat, I don't see much difference between\\nimaginary -inf/+inf values, and values from the BETWEEN \\\"date\\\" range\\nfrom the example SQL query. I have in the past wondered if\\n_bt_get_endpoint() should have been implemented that way -- we could\\ngo through _bt_search() instead, and get rid of that code. All we need\\nis insertion scan keys that can explicitly contain the same -inf/+inf\\nsentinel values. Maybe this also allows us to get rid of\\nBTScanInsertData.nextkey semantics (not sure offhand).\\n\\nAnother more concrete concern about the patch series comes from the\\nbackwards scan stuff. This is added by a later patch in the patch\\nseries, \\\"v39-0004-Extend-amskip-implementation-for-Btree.patch\\\". It\\nstrikes me as a bad thing that we cannot just do leaf-page-at-a-time\\nprocessing, without usually needing to hold a pin on the leaf page.\\nAfter all, ordinary backwards scans manage to avoid that today, albeit\\nby using trickery inside _bt_walk_left(). MDAM-style \\\"Maintenance of\\nIndex Order\\\" (as described on page 8) seems like a good goal for us\\nhere. I don't like the idea of doing ad-hoc duplicate TID elimination\\ninside nbtree, across calls made from the executor (whether it's\\nduring backwards skip scans, or at any other time). Not because it\\nseems to go against the approach taken by the MDAM paper (though it\\ndoes); just because it seems kludgy. (I think that Tom felt the same\\nway about the TID deduplication stuff in his own patch back in 2018,\\ntoo.)\\n\\nOpen question: What does all of this MDAM business mean for\\nScalarArrayOpExpr, if anything?\\n\\nI freely admit that I could easily be worrying over nothing here. But\\nif I am, I'd really like to know *why* that's the case.\\n\\n[1] http://vldb.org/conf/1995/P710.PDF\\n[2] https://blog.timescale.com/blog/how-we-made-distinct-queries-up-to-8000x-faster-on-postgresql/\\n[3] https://www.postgresql.org/message-id/flat/7f70bd5a-5d16-e05c-f0b4-2fdfc8873489%40BlueTreble.com\\n[4] https://www.postgresql.org/message-id/flat/14593.1517581614%40sss.pgh.pa.us#caf373b36332f25acb7673bff331c95e\\n--\\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Oct 2021 19:16:00 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Great to see some interest in the skip scan patch series again!\\r\\n\\r\\n> Like many difficult patches, the skip scan patch is not so much troubled by\\r\\n> problems with the implementation as it is troubled by\\r\\n> *ambiguity* about the design. Particularly concerning how skip scan meshes\\r\\n> with existing designs, as well as future designs -- particularly designs for\\r\\n> other MDAM techniques. I've started this thread to have a big picture\\r\\n> conversation about how to think about these things. Many other MDAM\\r\\n> techniques also seem highly appealing.\\r\\n\\r\\nI think it is good to have this discussion. In my opinion, Postgres could make really good use of some of the described MDAM techniques.\\r\\n\\r\\n> Much of the MDAM stuff is for data warehousing use-cases, while skip\\r\\n> scan/loose index scan is seen as more of an OLTP thing. But they are still\\r\\n> related, clearly.\\r\\n\\r\\nFWIW I think skip scan is very much data warehousing use-case related - hence why the TimescaleDb people in your [2] reference implemented a simple form of it already for their extension. Skip scan is a really useful feature for large data sets. However, I agree it is only one part of the bigger MDAM picture.\\r\\n\\r\\n> \\r\\n> My general concern is that the skip scan patch may currently be structured in\\r\\n> a way that paints us into a corner, MDAM-wise.\\r\\n> \\r\\n\\r\\nOne of the concerns I raised before was that the patch may be thinking too simplistically on some things, that would make it difficult to adopt more complex optimizations in the future. One concrete example can be illustrated by a different query on the sales table of the paper's example:\\r\\n\\r\\nSELECT DISTINCT dept, date WHERE item_class = 100\\r\\n\\r\\nThis should skip with prefix of (dept, date). Suppose we're at (dept, date) = (1, 2021-01-01) and it's skipping to the next prefix, the patch just implements what the MDAM paper describes as the 'probing' step. It finds the beginning of the next prefix. This could be for example (dept, date, item_class) = (1, 2021-01-02, 1). From there onwards, it would just scan the index until it finds item_class=100. What it should do however, is to first 'probe' for the next prefix value and then skip directly to (1, 2021-01-02, 100) (skipping item_class 1-99 altogether). The problem if it doesn't support this is that skip scan could have a quite unpredictable performance, because sometimes it'll end up going through most of the index where it should be skipping.\\r\\n\\r\\nA while ago, I spent quite some time trying to come up with an implementation that would work in this more general case. The nice thing is that with such a more generic implementation, you get almost all the features from the MDAM paper almost for free. I focused on the executor code, not on the planner code - the planner code is for the DISTINCT skip part very similar to the original patch and I hacked in a way to make it choose a 'skip scan' also for non-DISTINCT queries for testing purposes. For this discussion about MDAM, the planner part is less relevant though. There's still a lot of discussion and work on the planner-side too, but I think that is completely independent from each other.\\r\\n\\r\\nThe more generic patch I originally posted in [1], together with some technical considerations. That was quite a while ago so it obviously doesn't apply anymore on master. Therefore, I've attached a rebased version. Unfortunately, it's still based on an older version of the UniqueKeys patch - but since that patch is all planner machinery as well, it doesn't matter so much for the discussion about the executor code either.\\r\\n\\r\\nI believe if we want something that fits better with future MDAM use cases, we should take a closer look at the executor code of this patch to drive this discussion. The logic is definitely more complex than the original patch, however I believe it is also more flexible and future-proof.\\r\\n\\r\\n> \\r\\n> Another more concrete concern about the patch series comes from the\\r\\n> backwards scan stuff. This is added by a later patch in the patch series, \\\"v39-\\r\\n> 0004-Extend-amskip-implementation-for-Btree.patch\\\". It strikes me as a bad\\r\\n> thing that we cannot just do leaf-page-at-a-time processing, without usually\\r\\n> needing to hold a pin on the leaf page.\\r\\n> After all, ordinary backwards scans manage to avoid that today, albeit by\\r\\n> using trickery inside _bt_walk_left(). MDAM-style \\\"Maintenance of Index\\r\\n> Order\\\" (as described on page 8) seems like a good goal for us here. I don't\\r\\n> like the idea of doing ad-hoc duplicate TID elimination inside nbtree, across\\r\\n> calls made from the executor (whether it's during backwards skip scans, or at\\r\\n> any other time). Not because it seems to go against the approach taken by\\r\\n> the MDAM paper (though it does); just because it seems kludgy. (I think that\\r\\n> Tom felt the same way about the TID deduplication stuff in his own patch\\r\\n> back in 2018,\\r\\n> too.)\\r\\n\\r\\nIt's good to mention that the patch I attached does proper 'leaf-page-at-a-time' processing, so it avoids the problem you describe with v39. It is implemented instead in the same way as a \\\"regular\\\" index scan - we process the full leaf page and store the matched tuples in the local state. If a DISTINCT scan wants to do a skip, we check our local state first if that skipping would be possible with the matched tuples from the current page. Then we avoid double work and also the need to look at the same page again.\\r\\n\\r\\n> Open question: What does all of this MDAM business mean for\\r\\n> ScalarArrayOpExpr, if anything?\\r\\n> \\r\\n\\r\\nThis is a really interesting combination actually. I think, ideally, you'd probably get rid of it and provide full support for that with the 'skip' based approach (essentially the ScalarArrayOpExpr seems to do some form of skipping already - it transforms x IN (1,2,3) into 3 separate index scans for x).\\r\\nHowever, even without doing any work on it, it actually interacts nicely with the skip based approach.\\r\\n\\r\\nAs an example, here's some queries based on the 'sales' table of the paper with some data in it (18M rows total, see sales_query.sql attachment for the full example):\\r\\n\\r\\n-- terminology from paper: \\\"intervening range predicate\\\"\\r\\nselect date, sum(total_sales)\\r\\nfrom sales\\r\\nwhere dept between 2 and 3 and date between '2021-01-05' and '2021-01-10' and item_class=20 and store=250\\r\\ngroup by dept, date\\r\\n;\\r\\nPatch: Execution Time: 0.368 ms\\r\\nMaster: Execution Time: 416.792 ms\\r\\n\\r\\n-- terminology from paper: \\\"missing key predicate\\\"\\r\\nselect date, sum(total_sales)\\r\\nfrom sales\\r\\nwhere date between '2021-01-05' and '2021-01-10' and item_class=20 and store=250\\r\\ngroup by dept, date\\r\\n;\\r\\nPatch: Execution Time: 0.667 ms\\r\\nMaster: Execution Time: 654.684 ms\\r\\n\\r\\n-- terminology from paper: \\\"IN lists\\\" \\r\\n-- this is similar to the query from your example with an IN list\\r\\n-- in the current patch, this query is done with a skip scan with skip prefix (dept, date) and then the ScalarOpArray for item_class=(20,30,50)\\r\\nselect date, sum(total_sales)\\r\\nfrom sales\\r\\nwhere date between '2021-01-05' and '2021-01-10' and item_class in (20, 30, 50) and store=250\\r\\ngroup by dept, date\\r\\n;\\r\\nPatch: Execution Time: 1.767 ms\\r\\nMaster: Execution Time: 629.792 ms\\r\\n\\r\\nThe other mentioned MDAM optimizations in the paper (NOT =, general OR) are not implemented but don't seem to be conflicting at all with the current implementation - they seem to be just a matter of transforming the expressions into the right form.\\r\\n\\r\\nFrom the patch series above, v9-0001/v9-0002 is the UniqueKeys patch series, which focuses on the planner. v2-0001 is Dmitry's patch that extends it to make it possible to use UniqueKeys for the skip scan. Both of these are unfortunately still older patches, but because they are planner machinery they are less relevant to the discussion about the executor here.\\r\\nPatch v2-0002 contains most of my work and introduces all the executor logic for the skip scan and hooks up the planner for DISTINCT queries to use the skip scan.\\r\\nPatch v2-0003 is a planner hack that makes the planner pick a skip scan on virtually every possibility. This also enables the skip scan on the queries above that don't have a DISTINCT but where it could be useful.\\r\\n\\r\\n\\r\\n-Floris\\r\\n\\r\\n[1] https://www.postgresql.org/message-id/c5c5c974714a47f1b226c857699e8680@opammb0561.comp.optiver.com\",\n \"msg_date\": \"Sat, 23 Oct 2021 19:30:47 +0000\",\n \"msg_from\": \"Floris Van Nee <florisvannee@Optiver.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Thu, Oct 21, 2021 at 07:16:00PM -0700, Peter Geoghegan wrote:\\n>\\n> My general concern is that the skip scan patch may currently be\\n> structured in a way that paints us into a corner, MDAM-wise.\\n>\\n> Note that the MDAM paper treats skipping a prefix of columns as a case\\n> where the prefix is handled by pretending that there is a clause that\\n> looks like this: \\\"WHERE date between -inf AND +inf\\\" -- which is not so\\n> different from the original sales SQL query example that I have\\n> highlighted. We don't tend to think of queries like this (like my\\n> sales query) as in any way related to skip-scan, because we don't\\n> imagine that there is any skipping going on. But maybe we should\\n> recognize the similarities.\\n\\nTo avoid potential problems with extensibility in this sense, the\\nimplementation needs to explicitly work with sets of disjoint intervals\\nof values instead of simple prefix size, one set of intervals per scan\\nkey. An interesting idea, doesn't seem to be a big change in terms of\\nthe patch itself.\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 04:44:01 +0200\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Hi Peter,\\n\\nOn 10/21/21 22:16, Peter Geoghegan wrote:\\n> I returned to the 1995 paper \\\"Efficient Search of Multidimensional\\n> B-Trees\\\" [1] as part of the process of reviewing v39 of the skip scan\\n> patch, which was posted back in May. It's a great paper, and anybody\\n> involved in the skip scan effort should read it thoroughly (if they\\n> haven't already). It's easy to see why people get excited about skip\\n> scan [2]. But there is a bigger picture here.\\n> \\n\\nThanks for starting this thread !\\n\\nThe Index Skip Scan patch could affect a lot of areas, so keeping MDAM \\nin mind is definitely important.\\n\\nHowever, I think the key part to progress on the \\\"core\\\" functionality \\n(B-tree related changes) is to get the planner functionality in place \\nfirst. Hopefully we can make progress on that during the November \\nCommitFest based on Andy's patch.\\n\\nBest regards,\\n Jesper\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 08:10:56 -0400\",\n \"msg_from\": \"Jesper Pedersen <jesper.pedersen@redhat.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Sat, Oct 23, 2021 at 07:30:47PM +0000, Floris Van Nee wrote:\\n> \\n> From the patch series above, v9-0001/v9-0002 is the UniqueKeys patch series,\\n> which focuses on the planner. v2-0001 is Dmitry's patch that extends it to\\n> make it possible to use UniqueKeys for the skip scan. Both of these are\\n> unfortunately still older patches, but because they are planner machinery\\n> they are less relevant to the discussion about the executor here. Patch\\n> v2-0002 contains most of my work and introduces all the executor logic for\\n> the skip scan and hooks up the planner for DISTINCT queries to use the skip\\n> scan. Patch v2-0003 is a planner hack that makes the planner pick a skip\\n> scan on virtually every possibility. This also enables the skip scan on the\\n> queries above that don't have a DISTINCT but where it could be useful.\\n\\nThe patchset doesn't apply anymore:\\nhttp://cfbot.cputube.org/patch_36_1741.log\\n=== Applying patches on top of PostgreSQL commit ID a18b6d2dc288dfa6e7905ede1d4462edd6a8af47 ===\\n=== applying patch ./v2-0001-Extend-UniqueKeys.patch\\n[...]\\npatching file src/include/optimizer/paths.h\\nHunk #2 FAILED at 299.\\n1 out of 2 hunks FAILED -- saving rejects to file src/include/optimizer/paths.h.rej\\n\\nCould you send a rebased version? In the meantime I will change the status on\\nthe cf app to Waiting on Author.\\n\\n\\n\",\n \"msg_date\": \"Thu, 13 Jan 2022 18:36:12 +0800\",\n \"msg_from\": \"Julien Rouhaud <rjuju123@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> \\n> Could you send a rebased version? In the meantime I will change the status\\n> on the cf app to Waiting on Author.\\n\\nAttached a rebased version.\",\n \"msg_date\": \"Thu, 13 Jan 2022 15:27:08 +0000\",\n \"msg_from\": \"Floris Van Nee <florisvannee@Optiver.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"RE: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Thu, Jan 13, 2022 at 03:27:08PM +0000, Floris Van Nee wrote:\\n> >\\n> > Could you send a rebased version? In the meantime I will change the status\\n> > on the cf app to Waiting on Author.\\n>\\n> Attached a rebased version.\\n\\nFYI, I've attached this thread to the CF item as an informational one,\\nbut as there are some patches posted here, folks may get confused. For\\nthose who have landed here with no context, I feel obliged to mention\\nthat now there are two alternative patch series posted under the same\\nCF item:\\n\\n* the original one lives in [1], waiting for reviews since the last May\\n* an alternative one posted here from Floris\\n\\n[1]: https://www.postgresql.org/message-id/flat/20200609102247.jdlatmfyeecg52fi@localhost\\n\\n\\n\",\n \"msg_date\": \"Fri, 14 Jan 2022 08:55:26 +0100\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\\n> \\n> FYI, I've attached this thread to the CF item as an informational one,\\n> but as there are some patches posted here, folks may get confused. For\\n> those who have landed here with no context, I feel obliged to mention\\n> that now there are two alternative patch series posted under the same\\n> CF item:\\n> \\n> * the original one lives in [1], waiting for reviews since the last May\\n> * an alternative one posted here from Floris\\n\\nAh, I indeed wasn't sure of which patchset(s) should actually be reviewed.\\nIt's nice to have the alternative approach threads linkied in the commit fest,\\nbut it seems that the cfbot will use the most recent attachments as the only\\npatchset, thus leaving the \\\"original\\\" one untested.\\n\\nI'm not sure of what's the best approach in such situation. Maybe creating a\\ndifferent CF entry for each alternative, and link the other cf entry on the cf\\napp using the \\\"Add annotations\\\" or \\\"Links\\\" feature rather than attaching\\nthreads?\\n\\n\\n\",\n \"msg_date\": \"Fri, 14 Jan 2022 16:03:41 +0800\",\n \"msg_from\": \"Julien Rouhaud <rjuju123@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Fri, Jan 14, 2022 at 04:03:41PM +0800, Julien Rouhaud wrote:\\n> Hi,\\n>\\n> On Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\\n> >\\n> > FYI, I've attached this thread to the CF item as an informational one,\\n> > but as there are some patches posted here, folks may get confused. For\\n> > those who have landed here with no context, I feel obliged to mention\\n> > that now there are two alternative patch series posted under the same\\n> > CF item:\\n> >\\n> > * the original one lives in [1], waiting for reviews since the last May\\n> > * an alternative one posted here from Floris\\n>\\n> Ah, I indeed wasn't sure of which patchset(s) should actually be reviewed.\\n> It's nice to have the alternative approach threads linkied in the commit fest,\\n> but it seems that the cfbot will use the most recent attachments as the only\\n> patchset, thus leaving the \\\"original\\\" one untested.\\n>\\n> I'm not sure of what's the best approach in such situation. Maybe creating a\\n> different CF entry for each alternative, and link the other cf entry on the cf\\n> app using the \\\"Add annotations\\\" or \\\"Links\\\" feature rather than attaching\\n> threads?\\n\\nI don't mind having all of the alternatives under the same CF item, only\\none being tested seems to be only a small limitation of cfbot.\\n\\n\\n\",\n \"msg_date\": \"Sat, 22 Jan 2022 22:37:19 +0100\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-01-22 22:37:19 +0100, Dmitry Dolgov wrote:\\n> > On Fri, Jan 14, 2022 at 04:03:41PM +0800, Julien Rouhaud wrote:\\n> > Hi,\\n> >\\n> > On Fri, Jan 14, 2022 at 08:55:26AM +0100, Dmitry Dolgov wrote:\\n> > >\\n> > > FYI, I've attached this thread to the CF item as an informational one,\\n> > > but as there are some patches posted here, folks may get confused. For\\n> > > those who have landed here with no context, I feel obliged to mention\\n> > > that now there are two alternative patch series posted under the same\\n> > > CF item:\\n> > >\\n> > > * the original one lives in [1], waiting for reviews since the last May\\n> > > * an alternative one posted here from Floris\\n> >\\n> > Ah, I indeed wasn't sure of which patchset(s) should actually be reviewed.\\n> > It's nice to have the alternative approach threads linkied in the commit fest,\\n> > but it seems that the cfbot will use the most recent attachments as the only\\n> > patchset, thus leaving the \\\"original\\\" one untested.\\n> >\\n> > I'm not sure of what's the best approach in such situation. Maybe creating a\\n> > different CF entry for each alternative, and link the other cf entry on the cf\\n> > app using the \\\"Add annotations\\\" or \\\"Links\\\" feature rather than attaching\\n> > threads?\\n> \\n> I don't mind having all of the alternatives under the same CF item, only\\n> one being tested seems to be only a small limitation of cfbot.\\n\\nIMO it's pretty clear that having \\\"duelling\\\" patches below one CF entry is a\\nbad idea. I think they should be split, with inactive approaches marked as\\nreturned with feeback or whatnot.\\n\\nEither way, currently this patch fails on cfbot due to a new GUC:\\nhttps://api.cirrus-ci.com/v1/artifact/task/5134905372835840/log/src/test/recovery/tmp_check/regression.diffs\\nhttps://cirrus-ci.com/task/5134905372835840\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 21 Mar 2022 18:34:09 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Mon, Mar 21, 2022 at 06:34:09PM -0700, Andres Freund wrote:\\n>\\n> > I don't mind having all of the alternatives under the same CF item, only\\n> > one being tested seems to be only a small limitation of cfbot.\\n>\\n> IMO it's pretty clear that having \\\"duelling\\\" patches below one CF entry is a\\n> bad idea. I think they should be split, with inactive approaches marked as\\n> returned with feeback or whatnot.\\n\\nOn the other hand even for patches with dependencies (i.e. the patch A\\ndepends on the patch B) different CF items cause a lot of confusion for\\nreviewers. I guess for various flavours of the same patch it would be\\neven worse. But I don't have a strong opinion here.\\n\\n> Either way, currently this patch fails on cfbot due to a new GUC:\\n> https://api.cirrus-ci.com/v1/artifact/task/5134905372835840/log/src/test/recovery/tmp_check/regression.diffs\\n> https://cirrus-ci.com/task/5134905372835840\\n\\nThis seems to be easy to solve.\",\n \"msg_date\": \"Tue, 22 Mar 2022 21:00:08 +0100\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 22, 2022 at 2:34 PM Andres Freund <andres@anarazel.de> wrote:\\n> IMO it's pretty clear that having \\\"duelling\\\" patches below one CF entry is a\\n> bad idea. I think they should be split, with inactive approaches marked as\\n> returned with feeback or whatnot.\\n\\nI have the impression that this thread is getting some value from\\nhaving a CF entry, as a multi-person collaboration where people are\\ntrading ideas and also making progress that no one wants to mark as\\nreturned, but it's vexing for people managing the CF because it's not\\nreally proposed for 15. Perhaps what we lack is a new status, \\\"Work\\nIn Progress\\\" or something?\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 09:33:50 +1300\",\n \"msg_from\": \"Thomas Munro <thomas.munro@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Peter Geoghegan <pg@bowt.ie> writes:\\n> Like many difficult patches, the skip scan patch is not so much\\n> troubled by problems with the implementation as it is troubled by\\n> *ambiguity* about the design. Particularly concerning how skip scan\\n> meshes with existing designs, as well as future designs --\\n> particularly designs for other MDAM techniques. I've started this\\n> thread to have a big picture conversation about how to think about\\n> these things.\\n\\nPeter asked me off-list to spend some time thinking about the overall\\ndirection we ought to be pursuing here. I have done that, and here\\nare a few modest suggestions.\\n\\n1. Usually I'm in favor of doing this sort of thing in an index AM\\nagnostic way, but here I don't see much point. All of the ideas at\\nstake rely fundamentally on having a lexicographically-ordered multi\\ncolumn index; but we don't have any of those except btree, nor do\\nI think we're likely to get any soon. This motivates the general\\ntenor of my remarks below, which is \\\"do it in access/nbtree/ not in\\nthe planner\\\".\\n\\n2. The MDAM paper Peter cited is really interesting. You can see\\nfragments of those ideas in our existing btree code, particularly in\\nthe scan setup stuff that detects redundant or contradictory keys and\\ndetermines a scan start strategy. The special handling we implemented\\nawhile ago for ScalarArrayOp index quals is also a subset of what they\\nwere talking about. It seems to me that if we wanted to implement more\\nof those ideas, the relevant work should almost all be done in nbtree\\nproper. The planner would need only minor adjustments: btcostestimate\\nwould have to be fixed to understand the improvements, and there are\\nsome rules in indxpath.c that prevent us from passing \\\"too complicated\\\"\\nsets of indexquals to the AM, which would need to be relaxed or removed\\naltogether.\\n\\n3. \\\"Loose\\\" indexscan (i.e., sometimes re-descend from the tree root\\nto find the next index entry) is again something that seems like it's\\nmainly nbtree's internal problem. Loose scan is interesting if we\\nhave index quals for columns that are after the first column that lacks\\nan equality qual, otherwise not. I've worried in the past that we'd\\nneed planner/statistical support to figure out whether a loose scan\\nis likely to be useful compared to just plowing ahead in the index.\\nHowever, that seems to be rendered moot by the idea used in the current\\npatchsets, ie scan till we find that we'll have to step off the current\\npage, and re-descend at that point. (When and if we find that that\\nheuristic is inadequate, we could work on passing some statistical data\\nforward. But we don't need any in the v1 patch.) Again, we need some\\nwork in btcostestimate to understand how the index scan cost will be\\naffected, but I still don't see any pressing need for major planner\\nchanges or plan tree contents changes.\\n\\n4. I find each of the above ideas to be far more attractive than\\noptimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\\nunderstand why the current patchsets seem to be driven largely\\nby that single use-case. I wouldn't even bother with that for the\\ninitial patch. When we do get around to it, it still doesn't need\\nmajor planner support, I think --- again fixing the cost estimation\\nis the bulk of the work. Munro's original 2014 patch showed that we\\ndon't really need all that much to get the planner to build such a\\nplan; the problem is to convince it that that plan will be cheap.\\n\\nIn short: I would throw out just about all the planner infrastructure\\nthat's been proposed so far. It looks bulky, expensive, and\\ndrastically undercommented, and I don't think it's buying us anything\\nof commensurate value. The part of the planner that actually needs\\nserious thought is btcostestimate, which has been woefully neglected in\\nboth of the current patchsets.\\n\\nBTW, I've had a bee in my bonnet for a long time about whether some of\\nnbtree's scan setup work could be done once during planning, rather than\\nover again during each indexscan start. This issue might become more\\npressing if the work becomes significantly more complicated/expensive,\\nwhich these ideas might cause. But it's a refinement that could be\\nleft for later --- and in any case, the responsibility would still\\nfundamentally be nbtree's. I don't think the planner would do more\\nthan call some AM routine that could add decoration to an IndexScan\\nplan node.\\n\\nNow ... where did I put my flameproof vest?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 22 Mar 2022 16:55:49 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-03-22 16:55:49 -0400, Tom Lane wrote:\\n> 4. I find each of the above ideas to be far more attractive than\\n> optimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\\n> understand why the current patchsets seem to be driven largely\\n> by that single use-case.\\n\\nIt's something causing plenty pain in production environments... Obviously\\nit'd be even better if the optimization also triggered in cases like\\n SELECT some_indexed_col FROM blarg GROUP BY some_indexed_col\\nwhich seems to be what ORMs like to generate.\\n\\n\\n> BTW, I've had a bee in my bonnet for a long time about whether some of\\n> nbtree's scan setup work could be done once during planning, rather than\\n> over again during each indexscan start.\\n\\nIt does show up in simple-index-lookup heavy workloads. Not as a major thing,\\nbut it's there. And it's just architecturally displeasing :)\\n\\nAre you thinking of just moving the setup stuff in nbtree (presumably parts of\\n_bt_first() / _bt_preprocess_keys()) or also stuff in\\nExecIndexBuildScanKeys()?\\n\\nThe latter does show up a bit more heavily in profiles than nbtree specific\\nsetup, and given that it's generic executor type stuff, seems even more\\namenable to being moved to plan time.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 22 Mar 2022 16:06:14 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2022-03-22 16:55:49 -0400, Tom Lane wrote:\\n>> BTW, I've had a bee in my bonnet for a long time about whether some of\\n>> nbtree's scan setup work could be done once during planning, rather than\\n>> over again during each indexscan start.\\n\\n> It does show up in simple-index-lookup heavy workloads. Not as a major thing,\\n> but it's there. And it's just architecturally displeasing :)\\n> Are you thinking of just moving the setup stuff in nbtree (presumably parts of\\n> _bt_first() / _bt_preprocess_keys()) or also stuff in\\n> ExecIndexBuildScanKeys()?\\n\\nDidn't really have specifics in mind. The key stumbling block is\\nthat some (not all) of the work depends on knowing the specific\\nvalues of the indexqual comparison keys, so while you could do\\nthat work in advance for constant keys, you'd still have to be\\nprepared to do work at scan start for non-constant keys. I don't\\nhave a clear idea about how to factorize that effectively.\\n\\nA couple of other random ideas in this space:\\n\\n* I suspect that a lot of this work overlaps with the efforts that\\nbtcostestimate makes along the way to getting a cost estimate.\\nSo it's interesting to wonder whether we could refactor so that\\nbtcostestimate is integrated with this hypothetical plan-time key\\npreprocessing and doesn't duplicate work.\\n\\n* I think that we run through most or all of that preprocessing\\nlogic even for internal catalog accesses, where we know darn well\\nhow the keys are set up. We ought to think harder about how we\\ncould short-circuit pointless work in those code paths.\\n\\nI don't think any of this is an essential prerequisite to getting\\nsomething done for loose index scans, which ISTM ought to be the first\\npoint of attack for v16. Loose index scans per se shouldn't add much\\nto the key preprocessing costs. But these ideas likely would be\\nuseful to look into before anyone starts on the more complicated\\npreprocessing that would be needed for the ideas in the MDAM paper.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 22 Mar 2022 19:34:52 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\\n> Peter Geoghegan <pg@bowt.ie> writes:\\n> > Like many difficult patches, the skip scan patch is not so much\\n> > troubled by problems with the implementation as it is troubled by\\n> > *ambiguity* about the design. Particularly concerning how skip scan\\n> > meshes with existing designs, as well as future designs --\\n> > particularly designs for other MDAM techniques. I've started this\\n> > thread to have a big picture conversation about how to think about\\n> > these things.\\n>\\n> Peter asked me off-list to spend some time thinking about the overall\\n> direction we ought to be pursuing here. I have done that, and here\\n> are a few modest suggestions.\\n\\nThanks. To make sure I understand your proposal better, I have a couple\\nof questions:\\n\\n> In short: I would throw out just about all the planner infrastructure\\n> that's been proposed so far. It looks bulky, expensive, and\\n> drastically undercommented, and I don't think it's buying us anything\\n> of commensurate value.\\n\\nBroadly speaking planner related changes proposed in the patch so far\\nare: UniqueKey, taken from the neighbour thread about select distinct;\\nlist of uniquekeys to actually pass information about the specified\\nloose scan prefix into nbtree; some verification logic to prevent\\napplying skipping when it's not supported. I can imagine taking out\\nUniqueKeys and passing loose scan prefix in some other form (the other\\nparts seems to be essential) -- is that what you mean?\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 21:47:47 +0100\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Dmitry Dolgov <9erthalion6@gmail.com> writes:\\n> On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\\n>> In short: I would throw out just about all the planner infrastructure\\n>> that's been proposed so far. It looks bulky, expensive, and\\n>> drastically undercommented, and I don't think it's buying us anything\\n>> of commensurate value.\\n\\n> Broadly speaking planner related changes proposed in the patch so far\\n> are: UniqueKey, taken from the neighbour thread about select distinct;\\n> list of uniquekeys to actually pass information about the specified\\n> loose scan prefix into nbtree; some verification logic to prevent\\n> applying skipping when it's not supported. I can imagine taking out\\n> UniqueKeys and passing loose scan prefix in some other form (the other\\n> parts seems to be essential) -- is that what you mean?\\n\\nMy point is that for pure loose scans --- that is, just optimizing a scan,\\nnot doing AM-based duplicate-row-elimination --- you do not need to pass\\nany new data to btree at all. It can infer what to do on the basis of the\\nset of index quals it's handed.\\n\\nThe bigger picture here is that I think the reason this patch series has\\nfailed to progress is that it's too scattershot. You need to pick a\\nminimum committable feature and get that done, and then you can move on\\nto the next part. I think the minimum committable feature is loose scans,\\nwhich will require a fair amount of work in access/nbtree/ but very little\\nnew planner code, and will be highly useful in their own right even if we\\nnever do anything more.\\n\\nIn general I feel that the UniqueKey code is a solution looking for a\\nproblem, and that treating it as the core of the patchset is a mistake.\\nWe should be driving this work off of what nbtree needs to make progress,\\nand not building more infrastructure elsewhere than we have to. Maybe\\nwe'll end up with something that looks like UniqueKeys, but I'm far from\\nconvinced of that.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 17:32:46 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"> On Wed, Mar 23, 2022 at 05:32:46PM -0400, Tom Lane wrote:\\n> Dmitry Dolgov <9erthalion6@gmail.com> writes:\\n> > On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:\\n> >> In short: I would throw out just about all the planner infrastructure\\n> >> that's been proposed so far. It looks bulky, expensive, and\\n> >> drastically undercommented, and I don't think it's buying us anything\\n> >> of commensurate value.\\n>\\n> > Broadly speaking planner related changes proposed in the patch so far\\n> > are: UniqueKey, taken from the neighbour thread about select distinct;\\n> > list of uniquekeys to actually pass information about the specified\\n> > loose scan prefix into nbtree; some verification logic to prevent\\n> > applying skipping when it's not supported. I can imagine taking out\\n> > UniqueKeys and passing loose scan prefix in some other form (the other\\n> > parts seems to be essential) -- is that what you mean?\\n>\\n> My point is that for pure loose scans --- that is, just optimizing a scan,\\n> not doing AM-based duplicate-row-elimination --- you do not need to pass\\n> any new data to btree at all. It can infer what to do on the basis of the\\n> set of index quals it's handed.\\n>\\n> The bigger picture here is that I think the reason this patch series has\\n> failed to progress is that it's too scattershot. You need to pick a\\n> minimum committable feature and get that done, and then you can move on\\n> to the next part. I think the minimum committable feature is loose scans,\\n> which will require a fair amount of work in access/nbtree/ but very little\\n> new planner code, and will be highly useful in their own right even if we\\n> never do anything more.\\n>\\n> In general I feel that the UniqueKey code is a solution looking for a\\n> problem, and that treating it as the core of the patchset is a mistake.\\n> We should be driving this work off of what nbtree needs to make progress,\\n> and not building more infrastructure elsewhere than we have to. Maybe\\n> we'll end up with something that looks like UniqueKeys, but I'm far from\\n> convinced of that.\\n\\nI see. I'll need some thinking time about how it may look like (will\\nprobably return with more questions).\\n\\nThe CF item could be set to RwF, what would you say, Jesper?\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 23:22:32 +0100\",\n \"msg_from\": \"Dmitry Dolgov <9erthalion6@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On 3/23/22 18:22, Dmitry Dolgov wrote:\\n> \\n> The CF item could be set to RwF, what would you say, Jesper?\\n> \\n\\nWe want to thank the community for the feedback that we have received \\nover the years for this feature. Hopefully a future implementation can \\nuse Tom's suggestions to get closer to a committable solution.\\n\\nHere is the last CommitFest entry [1] for the archives.\\n\\nRwF\\n\\n[1] https://commitfest.postgresql.org/37/1741/\\n\\nBest regards,\\n Dmitry & Jesper\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 07:32:14 -0400\",\n \"msg_from\": \"Jesper Pedersen <jesper.pedersen@redhat.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 22, 2022 at 4:06 PM Andres Freund <andres@anarazel.de> wrote:\\n> Are you thinking of just moving the setup stuff in nbtree (presumably parts of\\n> _bt_first() / _bt_preprocess_keys()) or also stuff in\\n> ExecIndexBuildScanKeys()?\\n>\\n> The latter does show up a bit more heavily in profiles than nbtree specific\\n> setup, and given that it's generic executor type stuff, seems even more\\n> amenable to being moved to plan time.\\n\\nWhen I was working on the patch series that became the nbtree Postgres\\n12 work, this came up. At one point I discovered that using palloc0()\\nfor the insertion scankey in _bt_first() was a big problem with nested\\nloop joins -- it became a really noticeable bottleneck with one of my\\ntest cases. I independently discovered what Tom must have figured out\\nback in 2005, when he committed d961a56899. This led to my making the\\nnew insertion scan key structure (BTScanInsertData) not use dynamic\\nallocation. So _bt_first() is definitely performance critical for\\ncertain types of queries.\\n\\nWe could get rid of dynamic allocations for BTStackData in\\n_bt_first(), perhaps. The problem is that there is no simple,\\nreasonable proof of the maximum height on a B-tree, even though a\\nB-Tree with more than 7 or 8 levels seems extraordinarily unlikely.\\nYou could also invent a slow path (maybe do what we do in\\n_bt_insert_parent() in the event of a concurrent root page split/NULL\\nstack), but that runs into the problem of being awkward to test, and\\npretty ugly. It's doable, but I wouldn't do it unless there was a\\npretty noticeable payoff.\\n\\n-- \\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 17:13:16 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Peter Geoghegan <pg@bowt.ie> writes:\\n> We could get rid of dynamic allocations for BTStackData in\\n> _bt_first(), perhaps. The problem is that there is no simple,\\n> reasonable proof of the maximum height on a B-tree, even though a\\n> B-Tree with more than 7 or 8 levels seems extraordinarily unlikely.\\n\\nStart with a few entries preallocated, and switch to dynamically\\nallocated space if there turn out to be more levels than that,\\nperhaps? Not sure if it's worth the trouble.\\n\\nIn any case, what I was on about is _bt_preprocess_keys() and\\nadjacent code. I'm surprised that those aren't more expensive\\nthan one palloc in _bt_first. Maybe that logic falls through very\\nquickly in simple cases, though.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 20:21:54 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 22, 2022 at 1:55 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Peter asked me off-list to spend some time thinking about the overall\\n> direction we ought to be pursuing here.\\n\\nThanks for taking a look!\\n\\n\\\"5.5 Exploiting Key Prefixes\\\" and \\\"5.6 Ordered Retrieval\\\" from \\\"Modern\\nB-Tree Techniques\\\" are also good, BTW.\\n\\nThe terminology in this area is a mess. MySQL calls\\nSELECT-DISTINCT-that-matches-an-index \\\"loose index scans\\\". I think\\nthat you're talking about skip scan when you say \\\"loose index scan\\\".\\nSkip scan is where there is an omitted prefix of columns in the SQL\\nquery -- omitted columns after the first column that lack an equality\\nqual. Pretty sure that MySQL/InnoDB can't do that -- it can only\\n\\\"skip\\\" to the extent required to make\\nSELECT-DISTINCT-that-matches-an-index perform well, but that's about\\nit.\\n\\nIt might be useful for somebody to go write a \\\"taxonomy of MDAM\\ntechniques\\\", or a glossary. The existing \\\"Loose indexscan\\\" Postgres\\nwiki page doesn't seem like enough. Something very high level and\\nexplicit, with examples, just so we don't end up talking at cross\\npurposes too much.\\n\\n> 1. Usually I'm in favor of doing this sort of thing in an index AM\\n> agnostic way, but here I don't see much point. All of the ideas at\\n> stake rely fundamentally on having a lexicographically-ordered multi\\n> column index; but we don't have any of those except btree, nor do\\n> I think we're likely to get any soon. This motivates the general\\n> tenor of my remarks below, which is \\\"do it in access/nbtree/ not in\\n> the planner\\\".\\n\\nThat was my intuition all along, but I didn't quite have the courage\\nto say so -- sounds too much like something that an optimizer\\ndilettante like me would be expected to say. :-)\\n\\nSeems like one of those things where lots of high level details\\nintrinsically need to be figured out on-the-fly, at execution time,\\nrather than during planning. Perhaps it'll be easier to correctly\\ndetermine that a skip scan plan is the cheapest in practice than to\\naccurately cost skip scan plans. If the only alternative is a\\nsequential scan, then perhaps a very approximate cost model will work\\nwell enough. It's probably way too early to tell right now, though.\\n\\n> I've worried in the past that we'd\\n> need planner/statistical support to figure out whether a loose scan\\n> is likely to be useful compared to just plowing ahead in the index.\\n\\nI don't expect to be able to come up with a structure that leaves no\\nunanswered questions about future MDAM work -- it's not realistic to\\nexpect everything to just fall into place. But that's okay. Just\\nhaving everybody agree on roughly the right conceptual model is the\\nreally important thing. That now seems quite close, which I count as\\nreal progress.\\n\\n> 4. I find each of the above ideas to be far more attractive than\\n> optimizing SELECT-DISTINCT-that-matches-an-index, so I don't really\\n> understand why the current patchsets seem to be driven largely\\n> by that single use-case. I wouldn't even bother with that for the\\n> initial patch.\\n\\nI absolutely agree. I wondered about that myself in the past. My best\\nguess is that a certain segment of users are familiar with\\nSELECT-DISTINCT-that-matches-an-index from MySQL. And so to some\\nextent application frameworks evolved in a world where that capability\\nexisted. IIRC Jesper once said that Hibernate relied on this\\ncapability.\\n\\nIt's probably a lot easier to implement\\nSELECT-DISTINCT-that-matches-an-index if you have the MySQL storage\\nengine model, with concurrency control that's typically based on\\ntwo-phase locking. I think that MySQL does some amount of\\ndeduplication in its executor here -- and *not* in what they call the storage\\nengine. This is exactly what I'd like to avoid in Postgres; as I said\\n\\\"Maintenance of Index Order\\\" (as the paper calls it) seems important,\\nand not something to be added later on. Optimizer and executor layers\\nthat each barely know the difference between a skip scan and a full\\nindex scan seems like something we might actually want to aim for,\\nrather than avoid. Teaching nbtree to transform quals into ranges\\nsounds odd at first, but it seems like the right approach now, on\\nbalance -- that's the only *good* way to maintain index order.\\n(Maintaining index order is needed to avoid needing or relying on\\ndeduplication in the executor proper, which is even inappropriate in\\nan implementation of SELECT-DISTINCT-that-matches-an-index IMO.)\\n\\n--\\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 18:58:22 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 28, 2022 at 5:21 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> In any case, what I was on about is _bt_preprocess_keys() and\\n> adjacent code. I'm surprised that those aren't more expensive\\n> than one palloc in _bt_first. Maybe that logic falls through very\\n> quickly in simple cases, though.\\n\\nI assume that it doesn't really appear in very simple cases (also\\ncommon cases). But delaying the scan setup work until execution time\\ndoes seem ugly. That's probably a good enough reason to refactor.\\n\\n-- \\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 19:03:17 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"Peter Geoghegan <pg@bowt.ie> writes:\\n> The terminology in this area is a mess. MySQL calls\\n> SELECT-DISTINCT-that-matches-an-index \\\"loose index scans\\\". I think\\n> that you're talking about skip scan when you say \\\"loose index scan\\\".\\n> Skip scan is where there is an omitted prefix of columns in the SQL\\n> query -- omitted columns after the first column that lack an equality\\n> qual.\\n\\nRight, that's the case I had in mind --- apologies if my terminology\\nwas faulty. btree can actually handle such a case now, but what it\\nfails to do is re-descend from the tree root instead of plowing\\nforward in the index to find the next matching entry.\\n\\n> It might be useful for somebody to go write a \\\"taxonomy of MDAM\\n> techniques\\\", or a glossary.\\n\\n+1. We at least need to be sure we all are using these terms\\nthe same way.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 22:07:44 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 28, 2022 at 7:07 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Right, that's the case I had in mind --- apologies if my terminology\\n> was faulty. btree can actually handle such a case now, but what it\\n> fails to do is re-descend from the tree root instead of plowing\\n> forward in the index to find the next matching entry.\\n\\nKNNGIST seems vaguely related to what we'd build for nbtree skip scan,\\nthough. GiST index scans are \\\"inherently loose\\\", though. KNNGIST uses\\na pairing heap/priority queue, which seems like the kind of thing\\nnbtree skip scan can avoid.\\n\\n> +1. We at least need to be sure we all are using these terms\\n> the same way.\\n\\nYeah, there are *endless* opportunities for confusion here.\\n\\n-- \\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Mar 2022 20:19:15 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: MDAM techniques and Index Skip Scan patch\"\n }\n]","isConversational":false}}},{"rowIdx":52982,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hello there hackers,\n\nWe at Zalando have faced some issues around long running idle\ntransactions and were thinking about increasing the visibility of\npg_stat_* views to capture them easily. What I found is that currently\nin pg_stat_activity there is a lot of good information about the\ncurrent state of the process, but it is lacking the cumulative\ninformation on how much time the connection spent being idle, idle in\ntransaction or active, we would like to see cumulative values for each\nof these per connection. I believe it would be helpful for us and more\npeople out there if we could have total connection active and idle\ntime displayed in pg_stat_activity.\n\nTo provide this information I was digging into how the statistics\ncollector is working and found out there is already information like\ntotal time that a connection is active as well as idle computed in\npgstat_report_activity[1]. Ideally, this would be the values we would\nlike to see per process in pg_stat_activity.\n\nCurious to know your thoughts on this.\n\n[1]https://github.com/postgres/postgres/blob/cd3f429d9565b2e5caf0980ea7c707e37bc3b317/src/backend/utils/activity/backend_status.c#L593\n\n\n\n-- \nRegards,\nRafia Sabih\n\n\n","msg_date":"Fri, 22 Oct 2021 10:22:54 +0200","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Fri, 22 Oct 2021 at 10:22, Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n>\n> Hello there hackers,\n>\n> We at Zalando have faced some issues around long running idle\n> transactions and were thinking about increasing the visibility of\n> pg_stat_* views to capture them easily. What I found is that currently\n> in pg_stat_activity there is a lot of good information about the\n> current state of the process, but it is lacking the cumulative\n> information on how much time the connection spent being idle, idle in\n> transaction or active, we would like to see cumulative values for each\n> of these per connection. I believe it would be helpful for us and more\n> people out there if we could have total connection active and idle\n> time displayed in pg_stat_activity.\n>\n> To provide this information I was digging into how the statistics\n> collector is working and found out there is already information like\n> total time that a connection is active as well as idle computed in\n> pgstat_report_activity[1]. Ideally, this would be the values we would\n> like to see per process in pg_stat_activity.\n>\n> Curious to know your thoughts on this.\n>\n> [1]https://github.com/postgres/postgres/blob/cd3f429d9565b2e5caf0980ea7c707e37bc3b317/src/backend/utils/activity/backend_status.c#L593\n>\n>\n>\n> --\n> Regards,\n> Rafia Sabih\n\nPlease find the attached patch for the idea of our intentions.\nIt basically adds three attributes for idle, idle_in_transaction, and\nactive time respectively.\nPlease let me know your views on this and I shall add this to the\nupcoming commitfest for better tracking.\n\n\n--\nRegards,\nRafia Sabih","msg_date":"Tue, 26 Oct 2021 13:46:48 +0200","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Oct 26, 2021 at 5:17 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n>\n> >\n> > To provide this information I was digging into how the statistics\n> > collector is working and found out there is already information like\n> > total time that a connection is active as well as idle computed in\n> > pgstat_report_activity[1]. Ideally, this would be the values we would\n> > like to see per process in pg_stat_activity.\n> >\n> > Curious to know your thoughts on this.\n\n+1 for the idea\n\n> Please find the attached patch for the idea of our intentions.\n> It basically adds three attributes for idle, idle_in_transaction, and\n> active time respectively.\n> Please let me know your views on this and I shall add this to the\n> upcoming commitfest for better tracking.\n\nAbout the patch, IIUC earlier all the idle time was accumulated in the\n\"pgStatTransactionIdleTime\" counter, now with your patch you have\nintroduced one more counter which specifically tracks the\nSTATE_IDLEINTRANSACTION state. But my concern is that the\nSTATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\nthat looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\nbe accumulated in the \"pgStatTransactionIdleInTxnTime\" counter or\nthere should be a separate counter for that. But after your patch we\ncan not accumulate this in the \"pgStatTransactionIdleTime\" counter.\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 2 Nov 2021 13:29:42 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n>\n> On Tue, Oct 26, 2021 at 5:17 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> >\n> > >\n> > > To provide this information I was digging into how the statistics\n> > > collector is working and found out there is already information like\n> > > total time that a connection is active as well as idle computed in\n> > > pgstat_report_activity[1]. Ideally, this would be the values we would\n> > > like to see per process in pg_stat_activity.\n> > >\n> > > Curious to know your thoughts on this.\n>\n> +1 for the idea\n>\nThanks!\n\n> > Please find the attached patch for the idea of our intentions.\n> > It basically adds three attributes for idle, idle_in_transaction, and\n> > active time respectively.\n> > Please let me know your views on this and I shall add this to the\n> > upcoming commitfest for better tracking.\n>\n> About the patch, IIUC earlier all the idle time was accumulated in the\n> \"pgStatTransactionIdleTime\" counter, now with your patch you have\n> introduced one more counter which specifically tracks the\n> STATE_IDLEINTRANSACTION state. But my concern is that the\n> STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\n> that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\n> be accumulated in the \"pgStatTransactionIdleInTxnTime\" counter or\n> there should be a separate counter for that. But after your patch we\n> can not accumulate this in the \"pgStatTransactionIdleTime\" counter.\n>\nAs per your comments I have added it in pgStatTransactionIdleInTxnTime.\nPlease let me know if there are any further comments.\n\n-- \nRegards,\nRafia Sabih","msg_date":"Tue, 9 Nov 2021 15:58:27 +0100","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Nov 9, 2021 at 8:28 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n>\n> On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n> >\n\n> > About the patch, IIUC earlier all the idle time was accumulated in the\n> > \"pgStatTransactionIdleTime\" counter, now with your patch you have\n> > introduced one more counter which specifically tracks the\n> > STATE_IDLEINTRANSACTION state. But my concern is that the\n> > STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\n> > that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\n> > be accumulated in the \"pgStatTransactionIdleInTxnTime\" counter or\n> > there should be a separate counter for that. But after your patch we\n> > can not accumulate this in the \"pgStatTransactionIdleTime\" counter.\n> >\n> As per your comments I have added it in pgStatTransactionIdleInTxnTime.\n> Please let me know if there are any further comments.\n\nI have a few comments,\n\n nulls[29] = true;\n+ values[30] = true;\n+ values[31] = true;\n+ values[32] = true;\n\nThis looks wrong, this should be nulls[] = true not values[]=true.\n\nif ((beentry->st_state == STATE_RUNNING ||\n beentry->st_state == STATE_FASTPATH ||\n beentry->st_state == STATE_IDLEINTRANSACTION ||\n beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\n state != beentry->st_state)\n{\nif (beentry->st_state == STATE_RUNNING ||\nbeentry->st_state == STATE_FASTPATH)\n{\n pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n beentry->st_active_time = pgStatActiveTime;\n}\nelse if (beentry->st_state == STATE_IDLEINTRANSACTION ||\n beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED)\n{\n pgstat_count_conn_txn_idle_in_txn_time((PgStat_Counter) secs *\n1000000 + usecs);\n beentry->st_idle_in_transaction_time = pgStatTransactionIdleInTxnTime;\n}\nelse\n{\n pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);\n beentry->st_idle_time = pgStatTransactionIdleTime;\n}\n\nIt seems that in beentry->st_idle_time, you want to compute the\nSTATE_IDLE, but that state is not handled in the outer \"if\", that\nmeans whenever it comes out of the\nSTATE_IDLE, it will not enter inside this if check. You can run and\ntest, I am sure that with this patch the \"idle_time\" will always\nremain 0.\n\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Wed, 10 Nov 2021 13:35:31 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Wed, 10 Nov 2021 at 09:05, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n>\n> On Tue, Nov 9, 2021 at 8:28 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> >\n> > On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n> > >\n>\n> > > About the patch, IIUC earlier all the idle time was accumulated in the\n> > > \"pgStatTransactionIdleTime\" counter, now with your patch you have\n> > > introduced one more counter which specifically tracks the\n> > > STATE_IDLEINTRANSACTION state. But my concern is that the\n> > > STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\n> > > that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\n> > > be accumulated in the \"pgStatTransactionIdleInTxnTime\" counter or\n> > > there should be a separate counter for that. But after your patch we\n> > > can not accumulate this in the \"pgStatTransactionIdleTime\" counter.\n> > >\n> > As per your comments I have added it in pgStatTransactionIdleInTxnTime.\n> > Please let me know if there are any further comments.\n>\n> I have a few comments,\n>\n> nulls[29] = true;\n> + values[30] = true;\n> + values[31] = true;\n> + values[32] = true;\n>\n> This looks wrong, this should be nulls[] = true not values[]=true.\n>\n> if ((beentry->st_state == STATE_RUNNING ||\n> beentry->st_state == STATE_FASTPATH ||\n> beentry->st_state == STATE_IDLEINTRANSACTION ||\n> beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\n> state != beentry->st_state)\n> {\n> if (beentry->st_state == STATE_RUNNING ||\n> beentry->st_state == STATE_FASTPATH)\n> {\n> pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n> beentry->st_active_time = pgStatActiveTime;\n> }\n> else if (beentry->st_state == STATE_IDLEINTRANSACTION ||\n> beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED)\n> {\n> pgstat_count_conn_txn_idle_in_txn_time((PgStat_Counter) secs *\n> 1000000 + usecs);\n> beentry->st_idle_in_transaction_time = pgStatTransactionIdleInTxnTime;\n> }\n> else\n> {\n> pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);\n> beentry->st_idle_time = pgStatTransactionIdleTime;\n> }\n>\n> It seems that in beentry->st_idle_time, you want to compute the\n> STATE_IDLE, but that state is not handled in the outer \"if\", that\n> means whenever it comes out of the\n> STATE_IDLE, it will not enter inside this if check. You can run and\n> test, I am sure that with this patch the \"idle_time\" will always\n> remain 0.\n>\nThank you Dilip for your time on this.\nAnd yes you are right in both your observations.\nPlease find the attached patch for the updated version.\n\n-- \nRegards,\nRafia Sabih","msg_date":"Wed, 10 Nov 2021 09:17:22 +0100","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n>\n> > It seems that in beentry->st_idle_time, you want to compute the\n> > STATE_IDLE, but that state is not handled in the outer \"if\", that\n> > means whenever it comes out of the\n> > STATE_IDLE, it will not enter inside this if check. You can run and\n> > test, I am sure that with this patch the \"idle_time\" will always\n> > remain 0.\n> >\n> Thank you Dilip for your time on this.\n> And yes you are right in both your observations.\n> Please find the attached patch for the updated version.\n\nLooks fine now except these variable names,\n\n PgStat_Counter pgStatTransactionIdleTime = 0;\n+PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\n\nNow, pgStatTransactionIdleTime is collecting just the Idle time so\npgStatTransactionIdleTime should be renamed to \"pgStatIdleTime\" and\npgStatTransactionIdleInTxnTime should be renamed to\n\"pgStatTransactionIdleTime\"\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 15 Nov 2021 14:54:15 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n>\n> On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> >\n> > > It seems that in beentry->st_idle_time, you want to compute the\n> > > STATE_IDLE, but that state is not handled in the outer \"if\", that\n> > > means whenever it comes out of the\n> > > STATE_IDLE, it will not enter inside this if check. You can run and\n> > > test, I am sure that with this patch the \"idle_time\" will always\n> > > remain 0.\n> > >\n> > Thank you Dilip for your time on this.\n> > And yes you are right in both your observations.\n> > Please find the attached patch for the updated version.\n>\n> Looks fine now except these variable names,\n>\n> PgStat_Counter pgStatTransactionIdleTime = 0;\n> +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\n>\n> Now, pgStatTransactionIdleTime is collecting just the Idle time so\n> pgStatTransactionIdleTime should be renamed to \"pgStatIdleTime\" and\n> pgStatTransactionIdleInTxnTime should be renamed to\n> \"pgStatTransactionIdleTime\"\n>\nGood point!\nDone.\n\n\n-- \nRegards,\nRafia Sabih","msg_date":"Mon, 15 Nov 2021 12:15:46 +0100","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Mon, Nov 15, 2021 at 4:46 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n>\n> On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n> >\n> > On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> > >\n> > > > It seems that in beentry->st_idle_time, you want to compute the\n> > > > STATE_IDLE, but that state is not handled in the outer \"if\", that\n> > > > means whenever it comes out of the\n> > > > STATE_IDLE, it will not enter inside this if check. You can run and\n> > > > test, I am sure that with this patch the \"idle_time\" will always\n> > > > remain 0.\n> > > >\n> > > Thank you Dilip for your time on this.\n> > > And yes you are right in both your observations.\n> > > Please find the attached patch for the updated version.\n> >\n> > Looks fine now except these variable names,\n> >\n> > PgStat_Counter pgStatTransactionIdleTime = 0;\n> > +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\n> >\n> > Now, pgStatTransactionIdleTime is collecting just the Idle time so\n> > pgStatTransactionIdleTime should be renamed to \"pgStatIdleTime\" and\n> > pgStatTransactionIdleInTxnTime should be renamed to\n> > \"pgStatTransactionIdleTime\"\n> >\n> Good point!\n> Done.\n\n@@ -1018,7 +1019,7 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg,\nTimestampTz now)\n pgLastSessionReportTime = now;\n tsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\n tsmsg->m_active_time = pgStatActiveTime;\n- tsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\n+ tsmsg->m_idle_in_xact_time = pgStatIdleTime;\n\nI think this change is wrong, basically, \"tsmsg->m_idle_in_xact_time\"\nis used for counting the database level idle in transaction count, you\ncan check \"pg_stat_get_db_idle_in_transaction_time\" function for that.\nSo \"pgStatTransactionIdleTime\" is the variable counting the idle in\ntransaction time, pgStatIdleTime is just counting the idle time\noutside the transaction so if we make this change we are changing the\nmeaning of tsmsg->m_idle_in_xact_time.\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 15 Nov 2021 17:10:06 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Mon, 15 Nov 2021 at 12:40, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n>\n> On Mon, Nov 15, 2021 at 4:46 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> >\n> > On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\n> > >\n> > > On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> > > >\n> > > > > It seems that in beentry->st_idle_time, you want to compute the\n> > > > > STATE_IDLE, but that state is not handled in the outer \"if\", that\n> > > > > means whenever it comes out of the\n> > > > > STATE_IDLE, it will not enter inside this if check. You can run and\n> > > > > test, I am sure that with this patch the \"idle_time\" will always\n> > > > > remain 0.\n> > > > >\n> > > > Thank you Dilip for your time on this.\n> > > > And yes you are right in both your observations.\n> > > > Please find the attached patch for the updated version.\n> > >\n> > > Looks fine now except these variable names,\n> > >\n> > > PgStat_Counter pgStatTransactionIdleTime = 0;\n> > > +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\n> > >\n> > > Now, pgStatTransactionIdleTime is collecting just the Idle time so\n> > > pgStatTransactionIdleTime should be renamed to \"pgStatIdleTime\" and\n> > > pgStatTransactionIdleInTxnTime should be renamed to\n> > > \"pgStatTransactionIdleTime\"\n> > >\n> > Good point!\n> > Done.\n>\n> @@ -1018,7 +1019,7 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg,\n> TimestampTz now)\n> pgLastSessionReportTime = now;\n> tsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\n> tsmsg->m_active_time = pgStatActiveTime;\n> - tsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\n> + tsmsg->m_idle_in_xact_time = pgStatIdleTime;\n>\n> I think this change is wrong, basically, \"tsmsg->m_idle_in_xact_time\"\n> is used for counting the database level idle in transaction count, you\n> can check \"pg_stat_get_db_idle_in_transaction_time\" function for that.\n> So \"pgStatTransactionIdleTime\" is the variable counting the idle in\n> transaction time, pgStatIdleTime is just counting the idle time\n> outside the transaction so if we make this change we are changing the\n> meaning of tsmsg->m_idle_in_xact_time.\n\nGot it.\nUpdated\n\n-- \nRegards,\nRafia Sabih","msg_date":"Tue, 16 Nov 2021 12:35:52 +0100","msg_from":"Rafia Sabih <rafia.pghackers@gmail.com>","msg_from_op":true,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> > I think this change is wrong, basically, \"tsmsg->m_idle_in_xact_time\"\n> > is used for counting the database level idle in transaction count, you\n> > can check \"pg_stat_get_db_idle_in_transaction_time\" function for that.\n> > So \"pgStatTransactionIdleTime\" is the variable counting the idle in\n> > transaction time, pgStatIdleTime is just counting the idle time\n> > outside the transaction so if we make this change we are changing the\n> > meaning of tsmsg->m_idle_in_xact_time.\n>\n> Got it.\n> Updated\n\nOkay, thanks, I will look into it one more time early next week and if\nI see no issues then I will move it to RFC.\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 26 Nov 2021 13:57:28 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> Got it.\n> Updated\n\nThanks for the patch. +1 for adding the idle/idle_in_txn_time/active\ntime. I believe these are the total times a backend in its lifetime\naccumulates. For instance, if a backend runs 100 txns, then these new\ncolumns show the total time that the backend spent during these 100\ntxns, right?\n\nFew comments on the patch:\n\n1) Patch is missing a commit message. It is good to have a commit\nmessage describing the high-level of the feature.\n2) This patch needs to bump the catalog version, at the end of the\ncommit message, we usually keep a note \"Bump the catalog version\".\n3) It looks like the documentation is missing [1], for the new columns.\n4) When will these backend variables be reset? Is it at the backend\nstartup? Or some other? If these variables are reset only at the\nbackend startup and do they keep growing during the entire life of the\nbackend process? If yes, what happens for a long running backend/user\nsession, don't they get overflowed?\n\n+\n+ int64 st_active_time;\n+ int64 st_transaction_idle_time;\n+ int64 st_idle_time;\n } PgBackendStatus;\n\n5) Is there any way you can get them tested?\n6) What will be entries of st_active_time, st_transaction_idle_time,\nst_idle_time for non-backend processes, like bg writer, checkpointer,\nparallel worker, bg worker, logical replication launcher, stats\ncollector, sys logger etc?\n\n[1] https://www.postgresql.org/docs/devel/monitoring-stats.html#MONITORING-PG-STAT-ACTIVITY-VIEW\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Sat, 27 Nov 2021 08:00:13 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Sat, Nov 27, 2021 at 8:00 AM Bharath Rupireddy\n<bharath.rupireddyforpostgres@gmail.com> wrote:\n>\n> On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> > Got it.\n> > Updated\n>\n> Thanks for the patch. +1 for adding the idle/idle_in_txn_time/active\n> time. I believe these are the total times a backend in its lifetime\n> accumulates. For instance, if a backend runs 100 txns, then these new\n> columns show the total time that the backend spent during these 100\n> txns, right?\n>\n> Few comments on the patch:\n>\n> 1) Patch is missing a commit message. It is good to have a commit\n> message describing the high-level of the feature.\n> 2) This patch needs to bump the catalog version, at the end of the\n> commit message, we usually keep a note \"Bump the catalog version\".\n> 3) It looks like the documentation is missing [1], for the new columns.\n> 4) When will these backend variables be reset? Is it at the backend\n> startup? Or some other? If these variables are reset only at the\n> backend startup and do they keep growing during the entire life of the\n> backend process? If yes, what happens for a long running backend/user\n> session, don't they get overflowed?\n\nThis is a 64-bit variable so I am not sure do we really need to worry\nabout overflow? I mean if we are storing microseconds then also this\nwill be able to last for ~300,000 years no?\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 29 Nov 2021 11:32:44 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Fri, Oct 22, 2021 at 1:53 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\n> To provide this information I was digging into how the statistics\n> collector is working and found out there is already information like\n> total time that a connection is active as well as idle computed in\n> pgstat_report_activity[1]. Ideally, this would be the values we would\n> like to see per process in pg_stat_activity.\nIt's definitely useful to know how much time a backend has spent for\nquery executions. Once you've this info, you can easily calculate the\nidle time using this information: (now() - backend_start) -\nactive_time. But, I'm wondering why you need to distinguish between\nidle and idle in transactions - what's the usage? Either the backend\nis doing some work or it sits idle. Another useful information would\nbe when the last query execution was ended. From this information, you\ncan figure out whether a backend is idle for a long time since the\nlast execution and the execution time of the last query (query_end -\nquery_start).\n\nYou also need to update the documentation.\n\n-- \nThanks & Regards,\nKuntal Ghosh\n\n\n","msg_date":"Mon, 29 Nov 2021 20:34:14 +0530","msg_from":"Kuntal Ghosh <kuntalghosh.2007@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn Mon, Nov 29, 2021 at 11:04 PM Kuntal Ghosh\n<kuntalghosh.2007@gmail.com> wrote:\n>\n> You also need to update the documentation.\n\nYou also need to update rules.sql: https://cirrus-ci.com/task/6145265819189248\n\n\n","msg_date":"Wed, 12 Jan 2022 14:16:35 +0800","msg_from":"Julien Rouhaud <rjuju123@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn Wed, Jan 12, 2022 at 02:16:35PM +0800, Julien Rouhaud wrote:\n> \n> On Mon, Nov 29, 2021 at 11:04 PM Kuntal Ghosh\n> <kuntalghosh.2007@gmail.com> wrote:\n> >\n> > You also need to update the documentation.\n> \n> You also need to update rules.sql: https://cirrus-ci.com/task/6145265819189248\n\nThere has been multiple comments in the last two months that weren't addressed\nsince, and also the patch doesn't pass the regression tests anymore.\n\nRafia, do you plan to send a new version soon? Without update in the next few\ndays this patch will be closed as Returned with Feedback, per the commitfest\nrules.\n\n\n","msg_date":"Tue, 25 Jan 2022 22:22:45 +0800","msg_from":"Julien Rouhaud <rjuju123@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello,\n\n> Without update in the next few\n> days this patch will be closed as Returned with Feedback,\n\nThank you for the reminder, Julien.\n\nPer agreement with Rafia I have reworked the patch in the past days.\nThe new version 6 is now ready for review.\n\nRegards,\nSergey Dudoladov","msg_date":"Thu, 27 Jan 2022 11:43:26 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\n> \n> Per agreement with Rafia I have reworked the patch in the past days.\n> The new version 6 is now ready for review.\n\nGreat, thanks a lot Sergey!\n\nThe cfbot is happy with this new version:\nhttps://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\n\n\n","msg_date":"Thu, 27 Jan 2022 20:36:56 +0800","msg_from":"Julien Rouhaud <rjuju123@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi.\n\nAt Thu, 27 Jan 2022 20:36:56 +0800, Julien Rouhaud <rjuju123@gmail.com> wrote in\n> On Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\n> > \n> > Per agreement with Rafia I have reworked the patch in the past days.\n> > The new version 6 is now ready for review.\n> \n> Great, thanks a lot Sergey!\n> \n> The cfbot is happy with this new version:\n> https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\n\nI think we can easily add the duration of the current state to the two\nin pg_stat_get_activity and it would offer better information.\n\n\n \t\tif (beentry->st_state == STATE_RUNNING ||\n \t\t\tbeentry->st_state == STATE_FASTPATH)\n-\t\t\tpgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n+\t\t{\n+\t\t\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\n+\t\t\tbeentry->st_total_active_time += usecs_diff;\n+\t\t}\n\nThe two lines operates exactly the same way on variables with slightly\ndifferent behavior. pgStatActiveTime is reported at transaction end\nand reset at every tabstat reporting. st_total_active_time is reported\nimmediately and reset at session end. Since we do the latter, the\nfirst can be omitted by remembering the last values for the local\nvariables at every reporting. This needs additional two exporting\nfunction in pgstatfuncs like pgstat_get_my_queryid so others might\nthink differently.\n\nThe write operation to beentry needs to be enclosed by\nPGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\nbetter to move that writes to the PGSTAT_WRITE_ACTIVITY section just\nbelow.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Fri, 28 Jan 2022 14:36:31 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"At Mon, 29 Nov 2021 20:34:14 +0530, Kuntal Ghosh <kuntalghosh.2007@gmail.com> wrote in \n> active_time. But, I'm wondering why you need to distinguish between\n> idle and idle in transactions - what's the usage? Either the backend\n> is doing some work or it sits idle. Another useful information would\n\nI believe many people suffer from mysterious long idle in\ntransactions, which harm server performance many ways. In many cases\ntransactions with unexpectedly long idle time is an omen or a cause of\ntrouble.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Fri, 28 Jan 2022 14:40:24 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"At Fri, 28 Jan 2022 14:36:31 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in \n> Hi.\n> \n> At Thu, 27 Jan 2022 20:36:56 +0800, Julien Rouhaud <rjuju123@gmail.com> wrote in\n> > On Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\n> > > \n> > > Per agreement with Rafia I have reworked the patch in the past days.\n> > > The new version 6 is now ready for review.\n> > \n> > Great, thanks a lot Sergey!\n> > \n> > The cfbot is happy with this new version:\n> > https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\n> \n> I think we can easily add the duration of the current state to the two\n> in pg_stat_get_activity and it would offer better information.\n> \n> \n> \t\tif (beentry->st_state == STATE_RUNNING ||\n> \t\t\tbeentry->st_state == STATE_FASTPATH)\n> -\t\t\tpgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n> +\t\t{\n> +\t\t\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\n> +\t\t\tbeentry->st_total_active_time += usecs_diff;\n> +\t\t}\n> \n> The two lines operates exactly the same way on variables with slightly\n> different behavior. pgStatActiveTime is reported at transaction end\n> and reset at every tabstat reporting. st_total_active_time is reported\n> immediately and reset at session end. Since we do the latter, the\n\n> first can be omitted by remembering the last values for the local\n> variables at every reporting. This needs additional two exporting\n\nOf course it's typo(?) of \"values of the shared variables\".\nSorry for the mistake.\n\n> function in pgstatfuncs like pgstat_get_my_queryid so others might\n> think differently.\n> \n> The write operation to beentry needs to be enclosed by\n> PGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\n> better to move that writes to the PGSTAT_WRITE_ACTIVITY section just\n> below.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Fri, 28 Jan 2022 14:43:03 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nThank you for the reviews.\n\n> > The write operation to beentry needs to be enclosed by\n> > PGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\n> > better to move that writes to the PGSTAT_WRITE_ACTIVITY section just\n> > below.\n\nI have fixed it in the new version.\n\n> > if (beentry->st_state == STATE_RUNNING ||\n> > beentry->st_state == STATE_FASTPATH)\n> > - pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n> > + {\n> > + pgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\n> > + beentry->st_total_active_time += usecs_diff;\n> > + }\n> >\n> > The two lines operates exactly the same way on variables with slightly\n> > different behavior. pgStatActiveTime is reported at transaction end\n> > and reset at every tabstat reporting. st_total_active_time is reported\n> > immediately and reset at session end. Since we do the latter, the\n> > first can be omitted by remembering the last values for the local\n> > variables at every reporting. This needs additional two exporting\n>\n> Of course it's typo(?) of \"values of the shared variables\".\n\nCould you please elaborate on this idea ?\nSo we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\nused to report respective metrics in pg_stat_database.\nNow beentry's st_total_active_time / st_total_transaction_idle_time\nduplicates this info, so one may get rid of pgStat*Time counters. Is\nthe idea to report instead of them at every tabstat reporting the\ndifference between the last memorized value of st_total_*_time and\nits current value ?\n\n> > This needs additional two exporting\n> > function in pgstatfuncs like pgstat_get_my_queryid so others might\n> > think differently.\n\nWhat would be example functions to look at ?\n\nRegards,\nSergey","msg_date":"Mon, 31 Jan 2022 15:11:56 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"At Mon, 31 Jan 2022 15:11:56 +0100, Sergey Dudoladov <sergey.dudoladov@gmail.com> wrote in \n> > > if (beentry->st_state == STATE_RUNNING ||\n> > > beentry->st_state == STATE_FASTPATH)\n> > > - pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\n> > > + {\n> > > + pgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\n> > > + beentry->st_total_active_time += usecs_diff;\n> > > + }\n> > >\n> > > The two lines operates exactly the same way on variables with slightly\n> > > different behavior. pgStatActiveTime is reported at transaction end\n> > > and reset at every tabstat reporting. st_total_active_time is reported\n> > > immediately and reset at session end. Since we do the latter, the\n> > > first can be omitted by remembering the last values for the local\n> > > variables at every reporting. This needs additional two exporting\n> >\n> > Of course it's typo(?) of \"values of the shared variables\".\n> \n> Could you please elaborate on this idea ?\n> So we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\n> used to report respective metrics in pg_stat_database.\n> Now beentry's st_total_active_time / st_total_transaction_idle_time\n> duplicates this info, so one may get rid of pgStat*Time counters. Is\n> the idea to report instead of them at every tabstat reporting the\n> difference between the last memorized value of st_total_*_time and\n> its current value ?\n\nExactly. The attached first diff is the schetch of that.\n\n> > > This needs additional two exporting\n> > > function in pgstatfuncs like pgstat_get_my_queryid so others might\n> > > think differently.\n> \n> What would be example functions to look at ?\n\npgstat_get_my_queryid..\n\n\nAnd, it seems like I forgot to mention this, but as Kuntal suggested\n(in a different context and objective, though) upthraed, I think that\nwe can show realtime values in the two time fields by adding the time\nof the current state. See the attached second diff.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\ndiff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c\nindex 0646f53098..27419c1851 100644\n--- a/src/backend/postmaster/pgstat.c\n+++ b/src/backend/postmaster/pgstat.c\n@@ -249,8 +249,8 @@ static int\tpgStatXactRollback = 0;\n PgStat_Counter pgStatBlockReadTime = 0;\n PgStat_Counter pgStatBlockWriteTime = 0;\n static PgStat_Counter pgLastSessionReportTime = 0;\n-PgStat_Counter pgStatActiveTime = 0;\n-PgStat_Counter pgStatTransactionIdleTime = 0;\n+PgStat_Counter pgStatLastActiveTime = 0;\n+PgStat_Counter pgStatLastTransactionIdleTime = 0;\n SessionEndType pgStatSessionEndCause = DISCONNECT_NORMAL;\n \n /* Record that's written to 2PC state file when pgstat state is persisted */\n@@ -1026,8 +1026,13 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg, TimestampTz now)\n \t\t\tTimestampDifference(pgLastSessionReportTime, now, &secs, &usecs);\n \t\t\tpgLastSessionReportTime = now;\n \t\t\ttsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\n-\t\t\ttsmsg->m_active_time = pgStatActiveTime;\n-\t\t\ttsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\n+\n+\t\t\t/* send the difference since the last report */\n+\t\t\ttsmsg->m_active_time =\n+\t\t\t\tpgstat_get_my_active_time() - pgStatLastActiveTime;\n+\t\t\ttsmsg->m_idle_in_xact_time =\n+\t\t\t\tpgstat_get_my_transaction_idle_time() -\n+\t\t\t\tpgStatLastTransactionIdleTime;\n \t\t}\n \t\telse\n \t\t{\n@@ -1039,8 +1044,8 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg, TimestampTz now)\n \t\tpgStatXactRollback = 0;\n \t\tpgStatBlockReadTime = 0;\n \t\tpgStatBlockWriteTime = 0;\n-\t\tpgStatActiveTime = 0;\n-\t\tpgStatTransactionIdleTime = 0;\n+\t\tpgStatLastActiveTime = pgstat_get_my_active_time();\n+\t\tpgStatLastTransactionIdleTime = pgstat_get_my_transaction_idle_time();\n \t}\n \telse\n \t{\ndiff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c\nindex 5f15dcdc05..8b6836a662 100644\n--- a/src/backend/utils/activity/backend_status.c\n+++ b/src/backend/utils/activity/backend_status.c\n@@ -613,15 +613,9 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\n \t\t */\n \t\tif (beentry->st_state == STATE_RUNNING ||\n \t\t\tbeentry->st_state == STATE_FASTPATH)\n-\t\t{\n-\t\t\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\n \t\t\tactive_time_diff = usecs_diff;\n-\t\t}\n \t\telse\n-\t\t{\n-\t\t\tpgstat_count_conn_txn_idle_time((PgStat_Counter) usecs_diff);\n \t\t\ttransaction_idle_time_diff = usecs_diff;\n-\t\t}\n \t}\n \n \t/*\n@@ -1078,6 +1072,48 @@ pgstat_get_my_query_id(void)\n }\n \n \n+/* ----------\n+ * pgstat_get_my_active_time() -\n+ *\n+ * Return current backend's accumulated active time.\n+ */\n+uint64\n+pgstat_get_my_active_time(void)\n+{\n+\tif (!MyBEEntry)\n+\t\treturn 0;\n+\n+\t/*\n+\t * There's no need for a lock around pgstat_begin_read_activity /\n+\t * pgstat_end_read_activity here as it's only called from\n+\t * pg_stat_get_activity which is already protected, or from the same\n+\t * backend which means that there won't be concurrent writes.\n+\t */\n+\treturn MyBEEntry->st_total_active_time;\n+}\n+\n+\n+/* ----------\n+ * pgstat_get_my_transaction_idle_time() -\n+ *\n+ * Return current backend's accumulated in-transaction idel time.\n+ */\n+uint64\n+pgstat_get_my_transaction_idle_time(void)\n+{\n+\tif (!MyBEEntry)\n+\t\treturn 0;\n+\n+\t/*\n+\t * There's no need for a lock around pgstat_begin_read_activity /\n+\t * pgstat_end_read_activity here as it's only called from\n+\t * pg_stat_get_activity which is already protected, or from the same\n+\t * backend which means that there won't be concurrent writes.\n+\t */\n+\treturn MyBEEntry->st_total_transaction_idle_time;\n+}\n+\n+\n /* ----------\n * pgstat_fetch_stat_beentry() -\n *\ndiff --git a/src/include/pgstat.h b/src/include/pgstat.h\nindex e10d20222a..382d7202c1 100644\n--- a/src/include/pgstat.h\n+++ b/src/include/pgstat.h\n@@ -1185,10 +1185,6 @@ extern void pgstat_initstats(Relation rel);\n \t(pgStatBlockReadTime += (n))\n #define pgstat_count_buffer_write_time(n)\t\t\t\t\t\t\t\\\n \t(pgStatBlockWriteTime += (n))\n-#define pgstat_count_conn_active_time(n)\t\t\t\t\t\t\t\\\n-\t(pgStatActiveTime += (n))\n-#define pgstat_count_conn_txn_idle_time(n)\t\t\t\t\t\t\t\\\n-\t(pgStatTransactionIdleTime += (n))\n \n extern void pgstat_count_heap_insert(Relation rel, PgStat_Counter n);\n extern void pgstat_count_heap_update(Relation rel, bool hot);\ndiff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h\nindex 96d432ce49..1791dd6842 100644\n--- a/src/include/utils/backend_status.h\n+++ b/src/include/utils/backend_status.h\n@@ -309,6 +309,8 @@ extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);\n extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,\n \t\t\t\t\t\t\t\t\t\t\t\t\t int buflen);\n extern uint64 pgstat_get_my_query_id(void);\n+extern uint64 pgstat_get_my_active_time(void);\n+extern uint64 pgstat_get_my_transaction_idle_time(void);\n \n \n /* ----------\n\ndiff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c\nindex 8b6836a662..996f4e88d7 100644\n--- a/src/backend/utils/activity/backend_status.c\n+++ b/src/backend/utils/activity/backend_status.c\n@@ -587,10 +587,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\n \t * If the state has changed from \"active\" or \"idle in transaction\",\n \t * calculate the duration.\n \t */\n-\tif ((beentry->st_state == STATE_RUNNING ||\n-\t\t beentry->st_state == STATE_FASTPATH ||\n-\t\t beentry->st_state == STATE_IDLEINTRANSACTION ||\n-\t\t beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\n+\tif ((PGSTAT_IS_ACTIVE(beentry) || PGSTAT_IS_IDLEINTRANSACTION(beentry)) &&\n \t\tstate != beentry->st_state)\n \t{\n \t\tlong\t\tsecs;\n@@ -611,8 +608,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\n \t\t * 2. The latter values are reset to 0 once the data has been sent\n \t\t * to the statistics collector.\n \t\t */\n-\t\tif (beentry->st_state == STATE_RUNNING ||\n-\t\t\tbeentry->st_state == STATE_FASTPATH)\n+\t\tif (PGSTAT_IS_ACTIVE(beentry))\n \t\t\tactive_time_diff = usecs_diff;\n \t\telse\n \t\t\ttransaction_idle_time_diff = usecs_diff;\ndiff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c\nindex 7c2776c14c..48c0ffa33a 100644\n--- a/src/backend/utils/adt/pgstatfuncs.c\n+++ b/src/backend/utils/adt/pgstatfuncs.c\n@@ -675,6 +675,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\n \t\t{\n \t\t\tSockAddr\tzero_clientaddr;\n \t\t\tchar\t *clipped_activity;\n+\t\t\tint64\t\ttmp_time;\n \n \t\t\tswitch (beentry->st_state)\n \t\t\t{\n@@ -917,9 +918,25 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\n \t\t\telse\n \t\t\t\tvalues[29] = UInt64GetDatum(beentry->st_query_id);\n \n-\t\t\t/* convert to msec for display */\n-\t\t\tvalues[30] = Float8GetDatum(beentry->st_total_active_time / 1000.0) ;\n-\t\t\tvalues[31] = Float8GetDatum(beentry->st_total_transaction_idle_time / 1000.0);\n+\t\t\ttmp_time = beentry->st_total_active_time;\n+\n+\t\t\t/* add the realtime value to the counter if needed */\n+\t\t\tif (PGSTAT_IS_ACTIVE(beentry))\n+\t\t\t\ttmp_time +=\n+\t\t\t\t\tGetCurrentTimestamp() - beentry->st_state_start_timestamp;\n+\n+\t\t\t/* convert it to msec */\n+\t\t\tvalues[30] = Float8GetDatum(tmp_time / 1000.0) ;\n+\n+\t\t\ttmp_time = beentry->st_total_transaction_idle_time;\n+\n+\t\t\t/* add the realtime value to the counter if needed */\n+\t\t\tif (PGSTAT_IS_IDLEINTRANSACTION(beentry))\n+\t\t\t\ttmp_time +=\n+\t\t\t\t\tGetCurrentTimestamp() - beentry->st_state_start_timestamp;\n+\n+\t\t\t/* convert it to msec */\n+\t\t\tvalues[31] = Float8GetDatum(tmp_time);\n \t\t}\n \t\telse\n \t\t{\ndiff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h\nindex 1791dd6842..a03225c4f0 100644\n--- a/src/include/utils/backend_status.h\n+++ b/src/include/utils/backend_status.h\n@@ -235,6 +235,12 @@ typedef struct PgBackendStatus\n \t((before_changecount) == (after_changecount) && \\\n \t ((before_changecount) & 1) == 0)\n \n+/* macros to identify the states for time accounting */\n+#define PGSTAT_IS_ACTIVE(s)\t\t\t\t\t\t\t\t\t\t\t\t\\\n+\t((s)->st_state == STATE_RUNNING || (s)->st_state == STATE_FASTPATH)\n+#define PGSTAT_IS_IDLEINTRANSACTION(s)\t\t\t \\\n+\t((s)->st_state == STATE_IDLEINTRANSACTION ||\t\t\\\n+\t (s)->st_state == STATE_IDLEINTRANSACTION_ABORTED)\n \n /* ----------\n * LocalPgBackendStatus","msg_date":"Tue, 01 Feb 2022 13:55:16 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\n> > Could you please elaborate on this idea ?\n> > So we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\n> > used to report respective metrics in pg_stat_database.\n> > Now beentry's st_total_active_time / st_total_transaction_idle_time\n> > duplicates this info, so one may get rid of pgStat*Time counters. Is\n> > the idea to report instead of them at every tabstat reporting the\n> > difference between the last memorized value of st_total_*_time and\n> > its current value ?\n>\n> Exactly. The attached first diff is the schetch of that.\n\nThis diff actually adds more code than it removes and somewhat bloats the patch.\nI decided to incorporate it anyway because the diff explicitly shows\nthat time differences since the last report\nare send to the statistics collector,which is not immediately evident\nfrom the existing PgStat*Time counters.\nThat point may be worth further discussion though.\n\n\n> And, it seems like I forgot to mention this, but as Kuntal suggested\n> (in a different context and objective, though) upthraed, I think that\n> we can show realtime values in the two time fields by adding the time\n> of the current state. See the attached second diff.\n\nThat is exactly what we need in our infra, also included into the patch.\n\n\n@Kyotaro Horiguchi\nThank you for the contribution. I included both of your diffs with\nminor changes.\nShould I add you to the authors of the patch given that now half of it\nis basically your code ?\n\nRegards,\nSergey","msg_date":"Fri, 4 Feb 2022 10:58:24 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn 2022-02-04 10:58:24 +0100, Sergey Dudoladov wrote:\n> Thank you for the contribution. I included both of your diffs with\n> minor changes.\n\nThis currently doesn't apply: http://cfbot.cputube.org/patch_37_3405.log\n\nCould you rebase? Marking as waiting on author for now.\n\n- Andres\n\n\n","msg_date":"Mon, 21 Mar 2022 17:13:35 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello,\n\nI've updated the patch in preparation for the upcoming commitfest.\n\nRegards,\nSergey.","msg_date":"Mon, 13 Jun 2022 16:51:00 +0200","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn 6/13/22 4:51 PM, Sergey Dudoladov wrote:\n> Hello,\n>\n> I've updated the patch in preparation for the upcoming commitfest.\n\nI really like the idea of adding additional information like the ones in \nthis patch, so +1 for the patch.\n\nAs far the patch:\n\n@@ -864,7 +864,9 @@ CREATE VIEW pg_stat_activity AS\n s.backend_xmin,\n S.query_id,\n S.query,\n- S.backend_type\n+ S.backend_type,\n+ S.active_time,\n+ S.idle_in_transaction_time\n\nwhat about using total_active_time and total_idle_in_transaction_time?\n\nI think that would avoid any confusion and \"total_\" is also already used \nin other pg_stat_* views when appropriate.\n\n@@ -468,6 +468,13 @@ pgstat_beshutdown_hook(int code, Datum arg)\n\n beentry->st_procpid = 0; /* mark invalid */\n\n+ /*\n+ * Reset per-backend counters so that accumulated values for the \ncurrent\n+ * backend are not used for future backends.\n+ */\n+ beentry->st_total_active_time = 0;\n+ beentry->st_total_transaction_idle_time = 0;\n\nshouldn't that be in pgstat_bestart() instead? (and just let \npgstat_beshutdown_hook() set st_procpid to 0)\n\n /* so that functions can check if backend_status.c is up via \nMyBEEntry */\n@@ -524,6 +531,8 @@ pgstat_report_activity(BackendState state, const \nchar *cmd_str)\n TimestampTz start_timestamp;\n TimestampTz current_timestamp;\n int len = 0;\n+ int64 active_time_diff = 0;\n+ int64 transaction_idle_time_diff = 0;\n\nI think here we can use only a single variable say \"state_time_diff\" for \nexample, as later only one of those two is incremented anyway.\n\n+++ b/src/backend/utils/adt/pgstatfuncs.c\n@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)\n Datum\n pg_stat_get_activity(PG_FUNCTION_ARGS)\n {\n-#define PG_STAT_GET_ACTIVITY_COLS 30\n+#define PG_STAT_GET_ACTIVITY_COLS 32\n int num_backends = \npgstat_fetch_stat_numbackends();\n int curr_backend;\n int pid = PG_ARGISNULL(0) ? -1 : \nPG_GETARG_INT32(0);\n@@ -621,6 +621,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\n {\n SockAddr zero_clientaddr;\n char *clipped_activity;\n+ int64 time_to_report;\n\nwhat about total_time_to_report instead?\n\nAlso, maybe not for this patch but I think that would be also useful to \nget the total time waited (so that we would get more inside of what the \n\"active\" time was made of).\n\nRegards,\n\n-- \n\nBertrand Drouvot\nAmazon Web Services:https://aws.amazon.com\n\n\n\n","msg_date":"Mon, 4 Jul 2022 18:29:13 +0200","msg_from":"\"Drouvot, Bertrand\" <bdrouvot@amazon.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello,\n\nthanks for the helpful review. I have incorporated most of the\nsuggestions into the patch. I have also rebased and tested the patch\non top of the current master (2cd2569c72b89200).\n\n> + int64 active_time_diff = 0;\n> + int64 transaction_idle_time_diff = 0;\n>\n> I think here we can use only a single variable say \"state_time_diff\" for\n> example, as later only one of those two is incremented anyway.\n\nI have written it this way to avoid cluttering the critical section\nbetween PGSTAT_(BEGIN|END)_WRITE_ACTIVITY.\nWith two variable one can leave only actual increments in the section\nand check conditions / call TimestampDifference outside of it.\n\nRegards,\nSergey","msg_date":"Mon, 11 Jul 2022 16:43:12 +0200","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Rafia, Sergey,\n\nMany thanks for working on this!\n\n> I have incorporated most of the suggestions into the patch. I have also rebased and tested the patch on top of the current master\n\nI noticed that this patch is marked as \"Needs Review\" and decided to\ntake a look.\n\nI believe there is a bug in the implementation. Here is what I did:\n\n```\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\n...\ntotal_active_time | 9.128\ntotal_idle_in_transaction_time | 0\n\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\n...\ntotal_active_time | 10.626\ntotal_idle_in_transaction_time | 0\n\n57033 (master) =# BEGIN;\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\n...\ntotal_active_time | 17.443\ntotal_idle_in_transaction_time | 2314.703\n\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\n...\ntotal_active_time | 2514.635\ntotal_idle_in_transaction_time | 2314.703\n\n57033 (master) =# COMMIT;\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\n...\ntotal_active_time | 22.048\ntotal_idle_in_transaction_time | 7300.911\n```\n\nSo it looks like total_active_time tracks seconds when a user executes\nsingle expressions and milliseconds when running a transaction. It\nshould always track milliseconds.\n\nPlease use `git format-patch` for the next patch and provide a commit\nmessage, as it was previously pointed out by Bharath. Please specify\nthe list of the authors and reviewers and add a note about\nincrementing the catalog version.\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Wed, 13 Jul 2022 11:56:44 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi again,\n\n> 57033 (master) =# select * from pg_stat_activity where pid = 57033;\n> ...\n> total_active_time | 2514.635\n> total_idle_in_transaction_time | 2314.703\n>\n> 57033 (master) =# COMMIT;\n> 57033 (master) =# select * from pg_stat_activity where pid = 57033;\n> ...\n> total_active_time | 22.048\n> total_idle_in_transaction_time | 7300.911\n> ```\n\nMy previous message was wrong, total_active_time doesn't track\nseconds. I got confused by the name of this column. Still I'm pretty\nconfident it shouldn't decrease.\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Wed, 13 Jul 2022 12:09:13 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Rafia, Sergey,\n\n+1 for adding the total_active_time and total_idle_in_transaction_time \nto pg_stat_activity.\n\nI reviewed the patch and here are some comments.\n\n+ <entry role=\"catalog_table_entry\"><para role=\"column_definition\">\n+ <structfield>total_active_time</structfield> <type>double \nprecision</type>\n+ </para>\n+ <para>\n+ Time in milliseconds this backend spent in \n<literal>active</literal> and\n+ <literal>fastpath</literal> states.\n\nIs 'fastpath' an abbreviation of 'fastpath function call'?\nIf so, I feel it's clearer '<literal>fastpath function call</literal>' \nthan '<literal>fastpath</literal>'.\n\n\n+extern uint64 pgstat_get_my_active_time(void);\n+extern uint64 pgstat_get_my_transaction_idle_time(void);\n\nAre these functions necessary?\nIt seems they are not called from anywhere, doesn't it?\n\n-- \nRegards,\n\n--\nAtsushi Torikoshi\nNTT DATA CORPORATION\n\n\n","msg_date":"Thu, 14 Jul 2022 12:15:24 +0900","msg_from":"torikoshia <torikoshia@oss.nttdata.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello,\n\nI have addressed the reviews.\n\n@Aleksander Alekseev thanks for reporting the issue. I have altered\nthe patch to respect the behavior of pg_stat_activity, specifically\n[1]\n\n> Another important point is that when a server process is asked to display any of these statistics,\n> it first fetches the most recent report emitted by the collector process and then continues to use this snapshot\n> for all statistical views and functions until the end of its current transaction.\n> So the statistics will show static information as long as you continue the current transaction.\n\nFor the patch it means no computing of real-time values of\ntotal_*_time. Here is an example to illustrate the new behavior:\n\n=# begin;\n\n=*# select total_active_time, total_idle_in_transaction_time from\npg_stat_activity where pid = pg_backend_pid();\n total_active_time | total_idle_in_transaction_time\n-------------------+--------------------------------\n 0.124 | 10505.098\n\npostgres=*# select pg_sleep(10);\n\npostgres=*# select total_active_time, total_idle_in_transaction_time\nfrom pg_stat_activity where pid = pg_backend_pid();\n total_active_time | total_idle_in_transaction_time\n-------------------+--------------------------------\n 0.124 | 10505.098\n\npostgres=*# commit;\n\npostgres=# select total_active_time, total_idle_in_transaction_time\nfrom pg_stat_activity where pid = pg_backend_pid();\n total_active_time | total_idle_in_transaction_time\n-------------------+--------------------------------\n 10015.796 | 29322.831\n\n\n[1] https://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWS\n\nRegards,\nSergey","msg_date":"Thu, 21 Jul 2022 18:22:51 +0200","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi Sergey,\n\n> @Aleksander Alekseev thanks for reporting the issue. I have altered\n> the patch to respect the behavior of pg_stat_activity, specifically\n> [1]\n>\n> > Another important point is that when a server process is asked to\ndisplay any of these statistics,\n> > it first fetches the most recent report emitted by the collector\nprocess and then continues to use this snapshot\n> > for all statistical views and functions until the end of its current\ntransaction.\n> > So the statistics will show static information as long as you continue\nthe current transaction.\n>\n> For the patch it means no computing of real-time values of\n> total_*_time. Here is an example to illustrate the new behavior:\n>\n> =# begin;\n>\n> =*# select total_active_time, total_idle_in_transaction_time from\n> pg_stat_activity where pid = pg_backend_pid();\n> total_active_time | total_idle_in_transaction_time\n> -------------------+--------------------------------\n> 0.124 | 10505.098\n>\n> postgres=*# select pg_sleep(10);\n>\n> postgres=*# select total_active_time, total_idle_in_transaction_time\n> from pg_stat_activity where pid = pg_backend_pid();\n> total_active_time | total_idle_in_transaction_time\n> -------------------+--------------------------------\n> 0.124 | 10505.098\n>\n> postgres=*# commit;\n>\n> postgres=# select total_active_time, total_idle_in_transaction_time\n> from pg_stat_activity where pid = pg_backend_pid();\n> total_active_time | total_idle_in_transaction_time\n> -------------------+--------------------------------\n> 10015.796 | 29322.831\n>\n>\n> [1]\nhttps://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWS\n\nThis looks reasonable.\n\nWhat concerns me though is the fact that total_idle_in_transaction_time for\ngiven session doesn't seem to updated from the perspective of another\nsession:\n\n```\nsession1 (78376) =# BEGIN;\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\n...\ntotal_active_time | 40.057\ntotal_idle_in_transaction_time | 34322.171\n\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\n...\ntotal_active_time | 40.057\ntotal_idle_in_transaction_time | 34322.171\n\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\n...\ntotal_active_time | 46.908\ntotal_idle_in_transaction_time | 96933.518\n\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\n...\ntotal_active_time | 46.908\ntotal_idle_in_transaction_time | 96933.518 <--- doesn't change!\n\nsession1 (78376) =# COMMIT;\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\n...\ntotal_active_time | 47.16\ntotal_idle_in_transaction_time | 218422.143\n\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\ntotal_active_time | 50.631\ntotal_idle_in_transaction_time | 218422.143\n```\n\nThis is consistent with the current documentation:\n\n> Each individual server process transmits new statistical counts to the\ncollector just before going idle; so a query or transaction still in\nprogress does not affect the displayed totals.\n\nBut it makes me wonder if there will be a lot of use of\ntotal_idle_in_transaction_time and if the patch should actually alter this\nbehavior.\n\nThoughts?\n\n-- \nBest regards,\nAleksander Alekseev\n\nHi Sergey,> @Aleksander Alekseev thanks for reporting the issue. I have altered> the patch to respect the behavior of pg_stat_activity, specifically> [1]>> > Another important point is that when a server process is asked to display any of these statistics,> > it first fetches the most recent report emitted by the collector process and then continues to use this snapshot> > for all statistical views and functions until the end of its current transaction.> > So the statistics will show static information as long as you continue the current transaction.>> For the patch it means no computing of real-time values of> total_*_time. Here is an example to illustrate the new behavior:>> =# begin;>> =*# select total_active_time, total_idle_in_transaction_time from> pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 0.124 | 10505.098>> postgres=*# select pg_sleep(10);>> postgres=*# select total_active_time, total_idle_in_transaction_time> from pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 0.124 | 10505.098>> postgres=*# commit;>> postgres=# select total_active_time, total_idle_in_transaction_time> from pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 10015.796 | 29322.831>>> [1] https://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWSThis looks reasonable.What concerns me though is the fact that total_idle_in_transaction_time for given session doesn't seem to updated from the perspective of another session:```session1 (78376) =# BEGIN;session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 40.057total_idle_in_transaction_time | 34322.171session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 40.057total_idle_in_transaction_time | 34322.171session2 (78382) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 46.908total_idle_in_transaction_time | 96933.518session2 (78382) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 46.908total_idle_in_transaction_time | 96933.518 <--- doesn't change!session1 (78376) =# COMMIT;session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 47.16total_idle_in_transaction_time | 218422.143session2 (78382) =# select * from pg_stat_activity where pid = 78376;total_active_time | 50.631total_idle_in_transaction_time | 218422.143```This is consistent with the current documentation:> Each individual server process transmits new statistical counts to the collector just before going idle; so a query or transaction still in progress does not affect the displayed totals.But it makes me wonder if there will be a lot of use of total_idle_in_transaction_time and if the patch should actually alter this behavior.Thoughts?-- Best regards,Aleksander Alekseev","msg_date":"Fri, 22 Jul 2022 11:32:09 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi hackers,\n\nAll in all the patch seems to be in good shape.\n\n> This is consistent with the current documentation:\n>\n> > Each individual server process transmits new statistical counts to the collector just before going idle; so a query or transaction still in progress does not affect the displayed totals.\n>\n> But it makes me wonder if there will be a lot of use of total_idle_in_transaction_time and if the patch should actually alter this behavior.\n>\n> Thoughts?\n\nOn second thought, this is arguably out of scope of this particular\npatch and this particular discussion. In any case, having some stats\nis better than none.\n\nI'm going to change the status of the patch to \"Ready for Committer\"\nin a short time unless anyone has a second opinion.\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Fri, 22 Jul 2022 12:42:20 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello hackers,\n\nIs there anything we can do to facilitate merging of this patch ?\nIt has been in the \"ready-for-commiter\" state for 3 commitfests in a row now.\n\nWe would appreciate if the patch makes it to version 16: the need to\nmonitor idle-in-transaction connections is very real for us.\n\nRegards,\nSergey Dudoladov\n\n\n","msg_date":"Tue, 8 Nov 2022 19:11:43 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\nOn 2022-07-21 18:22:51 +0200, Sergey Dudoladov wrote:\n> From b5298301a3f5223bd78c519ddcddbd1bec9cf000 Mon Sep 17 00:00:00 2001\n> From: Sergey Dudoladov <sergey.dudoladov@gmail.com>\n> Date: Wed, 20 Apr 2022 23:47:37 +0200\n> Subject: [PATCH] pg_stat_activity: add 'total_active_time' and\n> 'total_idle_in_transaction_time'\n> \n> catversion bump because of the change in the contents of pg_stat_activity\n> \n> Author: Sergey Dudoladov, based on the initial version by Rafia Sabih\n> \n> Reviewed-by: Aleksander Alekseev, Bertrand Drouvot, and Atsushi Torikoshi\n> \n> Discussion: https://www.postgresql.org/message-id/flat/CA%2BFpmFcJF0vwi-SWW0wYO-c-FbhyawLq4tCpRDCJJ8Bq%3Dja-gA%40mail.gmail.com\n\nIsn't this patch breaking pg_stat_database? You removed\npgstat_count_conn_active_time() etc and the declaration for pgStatActiveTime /\npgStatTransactionIdleTime (but left the definition in pgstat_database.c), but\ndidn't replace it with anything afaics.\n\n\nSeparately from that, I'm a bit worried about starting to add accumulative\ncounters to pg_stat_activity. It's already gotten hard to use interactively\ndue to the number of columns - and why stop with the columns you suggest? Why\nnot show e.g. the total number of reads/writes, tuples inserted / deleted,\netc. as well?\n\nI wonder if we shouldn't add a pg_stat_session or such for per-connection\ncounters that show not the current state, but accumulated per-session state.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 8 Nov 2022 17:56:14 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Nov 8, 2022 at 6:56 PM Andres Freund <andres@anarazel.de> wrote:\n\n>\n> Separately from that, I'm a bit worried about starting to add accumulative\n> counters to pg_stat_activity. It's already gotten hard to use interactively\n> due to the number of columns - and why stop with the columns you suggest?\n> Why\n> not show e.g. the total number of reads/writes, tuples inserted / deleted,\n> etc. as well?\n>\n> I wonder if we shouldn't add a pg_stat_session or such for per-connection\n> counters that show not the current state, but accumulated per-session\n> state.\n>\n>\nI would much rather go down this route than make the existing table wider.\n\npg_stat_activity_state_duration (this patch) [the table - for a given\nbackend - would be empty if track_activities is off]\npg_stat_activity_bandwidth_usage (if someone feels like implementing the\nother items you mention)\n\n\nI'm not really buying into the idea of having multiple states sum their\ntimes together. I would expect one column per state. Actually two,\nbecause I also suggest that not only is the duration recorded, but a\ncounter be incremented each time a given state becomes the currently active\nstate. Seems like having access to a divisor of some form may be useful.\n\nSo 10 columns of data plus pid to join back to pg_stat_activity proper.\n\nDavid J.\n\nOn Tue, Nov 8, 2022 at 6:56 PM Andres Freund <andres@anarazel.de> wrote:\nSeparately from that, I'm a bit worried about starting to add accumulative\ncounters to pg_stat_activity. It's already gotten hard to use interactively\ndue to the number of columns - and why stop with the columns you suggest? Why\nnot show e.g. the total number of reads/writes, tuples inserted / deleted,\netc. as well?\n\nI wonder if we shouldn't add a pg_stat_session or such for per-connection\ncounters that show not the current state, but accumulated per-session state.I would much rather go down this route than make the existing table wider.pg_stat_activity_state_duration (this patch) [the table - for a given backend - would be empty if track_activities is off]pg_stat_activity_bandwidth_usage (if someone feels like implementing the other items you mention)I'm not really buying into the idea of having multiple states sum their times together. I would expect one column per state. Actually two, because I also suggest that not only is the duration recorded, but a counter be incremented each time a given state becomes the currently active state. Seems like having access to a divisor of some form may be useful.So 10 columns of data plus pid to join back to pg_stat_activity proper.David J.","msg_date":"Tue, 8 Nov 2022 19:25:27 -0700","msg_from":"\"David G. Johnston\" <david.g.johnston@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\n> Actually two, because I also suggest that not only is the duration recorded,\n> but a counter be incremented each time a given state becomes the currently\n> active state. Seems like having access to a divisor of some form may be\n> useful.\n\nWhat for?\n\n\n","msg_date":"Tue, 8 Nov 2022 18:37:27 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Tue, Nov 8, 2022 at 7:37 PM Andres Freund <andres@anarazel.de> wrote:\n\n> On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\n> > Actually two, because I also suggest that not only is the duration\n> recorded,\n> > but a counter be incremented each time a given state becomes the\n> currently\n> > active state. Seems like having access to a divisor of some form may be\n> > useful.\n>\n> What for?\n>\n\nBecause 5 hours of idle-in-transaction time in a single block means\nsomething different than the same 5 hours accumulated across 300 mini-idles.\n\nDavid J.\n\nOn Tue, Nov 8, 2022 at 7:37 PM Andres Freund <andres@anarazel.de> wrote:On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\n> Actually two, because I also suggest that not only is the duration recorded,\n> but a counter be incremented each time a given state becomes the currently\n> active state. Seems like having access to a divisor of some form may be\n> useful.\n\nWhat for?Because 5 hours of idle-in-transaction time in a single block means something different than the same 5 hours accumulated across 300 mini-idles.David J.","msg_date":"Tue, 8 Nov 2022 19:43:54 -0700","msg_from":"\"David G. Johnston\" <david.g.johnston@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello hackers,\n\nI've sketched the first version of a patch to add pg_stat_session.\nPlease review this early version.\n\nRegards,\nSergey.","msg_date":"Wed, 1 Feb 2023 21:45:52 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Wed, Feb 1, 2023 at 12:46 PM Sergey Dudoladov\n<sergey.dudoladov@gmail.com> wrote:\n>\n> I've sketched the first version of a patch to add pg_stat_session.\n> Please review this early version.\n\nHi Sergey!\n\nI've taken a look into the patch and got some notes.\n1. It is hard to understand what fastpath backend state is. What do\nfastpath metrics mean for a user?\n2. Anyway, the path \"if (PGSTAT_IS_FASTPATH(beentry))\" seems\nunreachable to me. I'm a bit surprised that compilers do not produce\nwarnings about it. Maybe I'm just wrong.\n3. Tests do not check any incrementation logic. I think we can have\nsome test that verifies delta for select some_counter from\npg_stat_session where pid = pg_backend_pid();\n4. Macroses like PGSTAT_IS_RUNNING do not look like net win in code\nreadability and PGSTAT prefix have no semantic load.\n\n\nThat's all I've found so far. Thank you!\n\nBest regards, Andrey Borodin.\n\nPS. We were doing on-air review session [0], I hope Nik will chime-in\nwith \"usability part of a review\".\n\n[0] https://youtu.be/vTV8XhWf3mo?t=2404\n\n\n","msg_date":"Thu, 16 Feb 2023 13:37:41 -0800","msg_from":"Andrey Borodin <amborodin86@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hello hackers,\n\nAndrey and Nik, thank you for selecting this patch for review in\nPostgres Hacking 101: I've modified the patch based both on your email\nand the video.\n\n1. Session statistics is now collected only for client backends. PG\ninternal processes like wal sender seem to stop sending statistics\nafter they have entered their respective main loops.\n2. Fastpath state now counts towards the running state. I think this\nspecial case does not justify tracking two extra numbers for every\nclient backend.\n3. I've added a small test for pg_stat_session similar to other tests\nin src/test/regress/sql/sysviews.sql\n4. Here are the pb_bench results requested in the video review:\n\nConditions: no assertions, number of transactions = 1000\nThe query: SELECT generate_series(1, 10000000) OFFSET 10000000;\nWith pg_stat_session:\n latency average = 324.480 ms\n tps = 3.081857 (without initial connection time)\n\nWithout pg_stat_session:\n latency average = 327.370 ms\n tps = 3.054651 (without initial connection time)\n\n\nRegards,\nSergey","msg_date":"Wed, 14 Jun 2023 07:50:35 +0200","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi Sergey,\n\nI've done a review of this patch. I found the patch idea very useful,\nthank you for the patch. I've noted something observing this patch:\n1. Patch can't be applied on the current master. My review is based on\n application of this patch over ac68323a878\n2. Being applied over ac68323a878 patch works as expected.\n3. Field names seems quite long to me (and they should be uniformly\n named with the same statistics in other views. For example\n \"running\" term is called \"active\" in pg_stat_database)\n4. Meaningless spaces at the end of line:\n - backend_status.c:586\n - monitoring.sgml:5857\n5. Patch adds\n\n usecs_diff = secs * 1000000 + usecs;\n\n at backend_status.c:pgstat_report_activity() to optimize\n calculations. But\n\n pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 +\nusecs);\n and \n pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 +\nusecs);\n\n are left in place after that.\n6. I'm not sure that I can understand the comment\n /* Keep statistics for pg_stat_database intact */\n at backend_status.c:600 correctly. Can you please explain it a\n little?\n7. Tests seems incomplete. It looks like we can check increments in\n all fields playing with transactions in tests.\n\nAlso, I have a thought about other possible improvements fitting to\nthis patch.\n\nThe view pg_stat_session is really needed in Postgres but I think it\nshould have much more statistics. I mean all resource statistics\nrelated to sessions. Every backend has instrumentation that tracks\nresource consumption. Data of this instrumentation goes to the\ncumulative statistics system and is used in monitoring extensions\n(like pg_stat_statements). I think pg_stat_session view is able to add\none more dimension of monitoring - a dimension of sessions. In my\nopinion this view should provide resource consumption statistics of\ncurrent sessions in two cumulative sets of statistics - since backend\nstart and since transaction start. Such view will be really useful in\nmonitoring of long running sessions and transactions providing\nresource consumption information besides timing statistics.\n\nregards, Andrei Zubkov\nPostgres Professional\n\n\n","msg_date":"Wed, 25 Oct 2023 16:12:42 +0300","msg_from":"Andrei Zubkov <zubkov@moonset.ru>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\n> I've done a review of this patch. I found the patch idea very useful,\n> thank you for the patch. I've noted something observing this patch:\n> 1. Patch can't be applied on the current master. My review is based on\n> application of this patch over ac68323a878\n\nOn top of that not sure if I see the patch on the November commitfest\n[1]. Please make sure it's there so that cfbot will check the patch.\n\n[1]: https://commitfest.postgresql.org/45/\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Wed, 25 Oct 2023 16:17:51 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi Aleksander,\n\nOn Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\n> On top of that not sure if I see the patch on the November commitfest\n> [1]. Please make sure it's there so that cfbot will check the patch.\n\nYes, this patch is listed on the November commitfest. cfbot says rebase\nneeded since 2023-08-21.\n\nregards, Andrei Zubkov\n\n\n\n","msg_date":"Wed, 25 Oct 2023 16:36:32 +0300","msg_from":"Andrei Zubkov <zubkov@moonset.ru>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi,\n\n> On Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\n> > On top of that not sure if I see the patch on the November commitfest\n> > [1]. Please make sure it's there so that cfbot will check the patch.\n>\n> Yes, this patch is listed on the November commitfest. cfbot says rebase\n> needed since 2023-08-21.\n\nYou are right, I missed the corresponding entry [1].\n\n[1]: https://commitfest.postgresql.org/45/3405/\n\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Wed, 25 Oct 2023 16:38:19 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"On Wed, 25 Oct 2023 at 19:06, Andrei Zubkov <zubkov@moonset.ru> wrote:\n>\n> Hi Aleksander,\n>\n> On Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\n> > On top of that not sure if I see the patch on the November commitfest\n> > [1]. Please make sure it's there so that cfbot will check the patch.\n>\n> Yes, this patch is listed on the November commitfest. cfbot says rebase\n> needed since 2023-08-21.\n\nI have changed the status of commitfest entry to \"Returned with\nFeedback\" as Andrei Zubkov's comments have not yet been resolved.\nPlease feel free to post an updated version of the patch and update\nthe commitfest entry accordingly.\n\nRegards,\nVignesh\n\n\n","msg_date":"Sun, 14 Jan 2024 16:34:44 +0530","msg_from":"vignesh C <vignesh21@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi all,\n\n@Andrei Zubkov\nI've modify the patch to address most of your comments.\n\n> I have a thought about other possible improvements fitting to this patch.\n> I think pg_stat_session view is able to add one more dimension of\nmonitoring - a dimension of sessions\n\nI would like to remind here about the initial scope of this patch. The main\ngoal of it was to ease tracking \"idle in transactions\" connections, a\nfeature that would really help in my work. The \"pg_stat_session\" came into\nplay only because the \"pg_stat_activity\" was seen as an unsuitable place\nfor the relevant counters. With that I still would like to maintaint the\nfocus on committing the \"idle in transactions\" part of pg_stat_session\nfirst.\n\nRegards,\nSergey","msg_date":"Thu, 1 Feb 2024 18:41:55 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi again,\n\n> It looks like we can check increments in all fields playing with\ntransactions in tests.\n\nI've added such tests.\n\nRegards,\nSergey","msg_date":"Thu, 1 Feb 2024 20:50:15 +0100","msg_from":"Sergey Dudoladov <sergey.dudoladov@gmail.com>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"},{"msg_contents":"Hi Sergei,\n\n> I still would like to maintaint the focus on committing the \"idle in\ntransactions\" part of pg_stat_session first.\n\nAgreed.\n\nI've done a review of version 0004. This version is applied successful\nover ce571434ae7, installcheck passed. The behavior of pg_stat_session\nview and corresponding function looks correct. I've didn't found any\nissues in the code.\n\nNotes about the current state of a patch:\n\nNaming\nthe view and function names 'pg_stat_session' seems correct for this\nparticular scope of a patch. However possible future resource\nconsumption statistics are valid for all backends (vacuum for example).\nRight now it is not clear for me if we can get resource statistics from\nthose backends while those are listed in the pg_stat_activity view but\nrenaming to something like 'pg_stat_backend' seems reasonable to me.\n\nDocs\n1. session states referenced in monitoring.sgml is not uniform with\nthose of the pg_stat_activity view.\nmonitoring.sgml:4635\nmonitoring.sgml:4644\n+ Time in milliseconds this backend spent in the\n<literal>running</literal> or <literal>fastpath</literal> state.\nI think those states should be referenced uniformly with\npg_stat_activity.\n\n2. Description of the 'pg_stat_get_session()' function might be as\nfollows:\n\n Returns a row, showing statistics about the client backend with the\n specified process ID, or one row per client backend if\n <literal>NULL</literal> is specified. The fields returned are the\n same as those of <structname>pg_stat_session</structname> view.\n\nThe main thought here is to get rid of 'each active backend' because\n'active backend' looks like backend in the 'active' state.\n\nTests\nCall to a non-existing function is depend on non-existence of a\nfunction, which can't be guaranteed absolutely. How about to do some\nkind of obvious error here? Couple examples follows:\n\nSELECT 0/0;\n\n- or -\n\nDO $$\nBEGIN\nRAISE 'test error';\nEND;\n$$ LANGUAGE plpgsql;\n\nMy personal choice would be the last one.\n\n-- \nregards, Andrei Zubkov\nPostgres Professional\n\n\n\n","msg_date":"Mon, 12 Feb 2024 15:30:58 +0300","msg_from":"Andrei Zubkov <zubkov@moonset.ru>","msg_from_op":false,"msg_subject":"Re: Add connection active, idle time to pg_stat_activity"}],"string":"[\n {\n \"msg_contents\": \"Hello there hackers,\\n\\nWe at Zalando have faced some issues around long running idle\\ntransactions and were thinking about increasing the visibility of\\npg_stat_* views to capture them easily. What I found is that currently\\nin pg_stat_activity there is a lot of good information about the\\ncurrent state of the process, but it is lacking the cumulative\\ninformation on how much time the connection spent being idle, idle in\\ntransaction or active, we would like to see cumulative values for each\\nof these per connection. I believe it would be helpful for us and more\\npeople out there if we could have total connection active and idle\\ntime displayed in pg_stat_activity.\\n\\nTo provide this information I was digging into how the statistics\\ncollector is working and found out there is already information like\\ntotal time that a connection is active as well as idle computed in\\npgstat_report_activity[1]. Ideally, this would be the values we would\\nlike to see per process in pg_stat_activity.\\n\\nCurious to know your thoughts on this.\\n\\n[1]https://github.com/postgres/postgres/blob/cd3f429d9565b2e5caf0980ea7c707e37bc3b317/src/backend/utils/activity/backend_status.c#L593\\n\\n\\n\\n-- \\nRegards,\\nRafia Sabih\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 10:22:54 +0200\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Fri, 22 Oct 2021 at 10:22, Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n>\\n> Hello there hackers,\\n>\\n> We at Zalando have faced some issues around long running idle\\n> transactions and were thinking about increasing the visibility of\\n> pg_stat_* views to capture them easily. What I found is that currently\\n> in pg_stat_activity there is a lot of good information about the\\n> current state of the process, but it is lacking the cumulative\\n> information on how much time the connection spent being idle, idle in\\n> transaction or active, we would like to see cumulative values for each\\n> of these per connection. I believe it would be helpful for us and more\\n> people out there if we could have total connection active and idle\\n> time displayed in pg_stat_activity.\\n>\\n> To provide this information I was digging into how the statistics\\n> collector is working and found out there is already information like\\n> total time that a connection is active as well as idle computed in\\n> pgstat_report_activity[1]. Ideally, this would be the values we would\\n> like to see per process in pg_stat_activity.\\n>\\n> Curious to know your thoughts on this.\\n>\\n> [1]https://github.com/postgres/postgres/blob/cd3f429d9565b2e5caf0980ea7c707e37bc3b317/src/backend/utils/activity/backend_status.c#L593\\n>\\n>\\n>\\n> --\\n> Regards,\\n> Rafia Sabih\\n\\nPlease find the attached patch for the idea of our intentions.\\nIt basically adds three attributes for idle, idle_in_transaction, and\\nactive time respectively.\\nPlease let me know your views on this and I shall add this to the\\nupcoming commitfest for better tracking.\\n\\n\\n--\\nRegards,\\nRafia Sabih\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:46:48 +0200\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 5:17 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n>\\n> >\\n> > To provide this information I was digging into how the statistics\\n> > collector is working and found out there is already information like\\n> > total time that a connection is active as well as idle computed in\\n> > pgstat_report_activity[1]. Ideally, this would be the values we would\\n> > like to see per process in pg_stat_activity.\\n> >\\n> > Curious to know your thoughts on this.\\n\\n+1 for the idea\\n\\n> Please find the attached patch for the idea of our intentions.\\n> It basically adds three attributes for idle, idle_in_transaction, and\\n> active time respectively.\\n> Please let me know your views on this and I shall add this to the\\n> upcoming commitfest for better tracking.\\n\\nAbout the patch, IIUC earlier all the idle time was accumulated in the\\n\\\"pgStatTransactionIdleTime\\\" counter, now with your patch you have\\nintroduced one more counter which specifically tracks the\\nSTATE_IDLEINTRANSACTION state. But my concern is that the\\nSTATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\\nthat looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\\nbe accumulated in the \\\"pgStatTransactionIdleInTxnTime\\\" counter or\\nthere should be a separate counter for that. But after your patch we\\ncan not accumulate this in the \\\"pgStatTransactionIdleTime\\\" counter.\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 13:29:42 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n>\\n> On Tue, Oct 26, 2021 at 5:17 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> >\\n> > >\\n> > > To provide this information I was digging into how the statistics\\n> > > collector is working and found out there is already information like\\n> > > total time that a connection is active as well as idle computed in\\n> > > pgstat_report_activity[1]. Ideally, this would be the values we would\\n> > > like to see per process in pg_stat_activity.\\n> > >\\n> > > Curious to know your thoughts on this.\\n>\\n> +1 for the idea\\n>\\nThanks!\\n\\n> > Please find the attached patch for the idea of our intentions.\\n> > It basically adds three attributes for idle, idle_in_transaction, and\\n> > active time respectively.\\n> > Please let me know your views on this and I shall add this to the\\n> > upcoming commitfest for better tracking.\\n>\\n> About the patch, IIUC earlier all the idle time was accumulated in the\\n> \\\"pgStatTransactionIdleTime\\\" counter, now with your patch you have\\n> introduced one more counter which specifically tracks the\\n> STATE_IDLEINTRANSACTION state. But my concern is that the\\n> STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\\n> that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\\n> be accumulated in the \\\"pgStatTransactionIdleInTxnTime\\\" counter or\\n> there should be a separate counter for that. But after your patch we\\n> can not accumulate this in the \\\"pgStatTransactionIdleTime\\\" counter.\\n>\\nAs per your comments I have added it in pgStatTransactionIdleInTxnTime.\\nPlease let me know if there are any further comments.\\n\\n-- \\nRegards,\\nRafia Sabih\",\n \"msg_date\": \"Tue, 9 Nov 2021 15:58:27 +0100\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 9, 2021 at 8:28 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n>\\n> On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n> >\\n\\n> > About the patch, IIUC earlier all the idle time was accumulated in the\\n> > \\\"pgStatTransactionIdleTime\\\" counter, now with your patch you have\\n> > introduced one more counter which specifically tracks the\\n> > STATE_IDLEINTRANSACTION state. But my concern is that the\\n> > STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\\n> > that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\\n> > be accumulated in the \\\"pgStatTransactionIdleInTxnTime\\\" counter or\\n> > there should be a separate counter for that. But after your patch we\\n> > can not accumulate this in the \\\"pgStatTransactionIdleTime\\\" counter.\\n> >\\n> As per your comments I have added it in pgStatTransactionIdleInTxnTime.\\n> Please let me know if there are any further comments.\\n\\nI have a few comments,\\n\\n nulls[29] = true;\\n+ values[30] = true;\\n+ values[31] = true;\\n+ values[32] = true;\\n\\nThis looks wrong, this should be nulls[] = true not values[]=true.\\n\\nif ((beentry->st_state == STATE_RUNNING ||\\n beentry->st_state == STATE_FASTPATH ||\\n beentry->st_state == STATE_IDLEINTRANSACTION ||\\n beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\\n state != beentry->st_state)\\n{\\nif (beentry->st_state == STATE_RUNNING ||\\nbeentry->st_state == STATE_FASTPATH)\\n{\\n pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n beentry->st_active_time = pgStatActiveTime;\\n}\\nelse if (beentry->st_state == STATE_IDLEINTRANSACTION ||\\n beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED)\\n{\\n pgstat_count_conn_txn_idle_in_txn_time((PgStat_Counter) secs *\\n1000000 + usecs);\\n beentry->st_idle_in_transaction_time = pgStatTransactionIdleInTxnTime;\\n}\\nelse\\n{\\n pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);\\n beentry->st_idle_time = pgStatTransactionIdleTime;\\n}\\n\\nIt seems that in beentry->st_idle_time, you want to compute the\\nSTATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\nmeans whenever it comes out of the\\nSTATE_IDLE, it will not enter inside this if check. You can run and\\ntest, I am sure that with this patch the \\\"idle_time\\\" will always\\nremain 0.\\n\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 10 Nov 2021 13:35:31 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Wed, 10 Nov 2021 at 09:05, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n>\\n> On Tue, Nov 9, 2021 at 8:28 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> >\\n> > On Tue, 2 Nov 2021 at 09:00, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n> > >\\n>\\n> > > About the patch, IIUC earlier all the idle time was accumulated in the\\n> > > \\\"pgStatTransactionIdleTime\\\" counter, now with your patch you have\\n> > > introduced one more counter which specifically tracks the\\n> > > STATE_IDLEINTRANSACTION state. But my concern is that the\\n> > > STATE_IDLEINTRANSACTION_ABORTED is still computed under STATE_IDLE and\\n> > > that looks odd to me. Either STATE_IDLEINTRANSACTION_ABORTED should\\n> > > be accumulated in the \\\"pgStatTransactionIdleInTxnTime\\\" counter or\\n> > > there should be a separate counter for that. But after your patch we\\n> > > can not accumulate this in the \\\"pgStatTransactionIdleTime\\\" counter.\\n> > >\\n> > As per your comments I have added it in pgStatTransactionIdleInTxnTime.\\n> > Please let me know if there are any further comments.\\n>\\n> I have a few comments,\\n>\\n> nulls[29] = true;\\n> + values[30] = true;\\n> + values[31] = true;\\n> + values[32] = true;\\n>\\n> This looks wrong, this should be nulls[] = true not values[]=true.\\n>\\n> if ((beentry->st_state == STATE_RUNNING ||\\n> beentry->st_state == STATE_FASTPATH ||\\n> beentry->st_state == STATE_IDLEINTRANSACTION ||\\n> beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\\n> state != beentry->st_state)\\n> {\\n> if (beentry->st_state == STATE_RUNNING ||\\n> beentry->st_state == STATE_FASTPATH)\\n> {\\n> pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n> beentry->st_active_time = pgStatActiveTime;\\n> }\\n> else if (beentry->st_state == STATE_IDLEINTRANSACTION ||\\n> beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED)\\n> {\\n> pgstat_count_conn_txn_idle_in_txn_time((PgStat_Counter) secs *\\n> 1000000 + usecs);\\n> beentry->st_idle_in_transaction_time = pgStatTransactionIdleInTxnTime;\\n> }\\n> else\\n> {\\n> pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);\\n> beentry->st_idle_time = pgStatTransactionIdleTime;\\n> }\\n>\\n> It seems that in beentry->st_idle_time, you want to compute the\\n> STATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\n> means whenever it comes out of the\\n> STATE_IDLE, it will not enter inside this if check. You can run and\\n> test, I am sure that with this patch the \\\"idle_time\\\" will always\\n> remain 0.\\n>\\nThank you Dilip for your time on this.\\nAnd yes you are right in both your observations.\\nPlease find the attached patch for the updated version.\\n\\n-- \\nRegards,\\nRafia Sabih\",\n \"msg_date\": \"Wed, 10 Nov 2021 09:17:22 +0100\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n>\\n> > It seems that in beentry->st_idle_time, you want to compute the\\n> > STATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\n> > means whenever it comes out of the\\n> > STATE_IDLE, it will not enter inside this if check. You can run and\\n> > test, I am sure that with this patch the \\\"idle_time\\\" will always\\n> > remain 0.\\n> >\\n> Thank you Dilip for your time on this.\\n> And yes you are right in both your observations.\\n> Please find the attached patch for the updated version.\\n\\nLooks fine now except these variable names,\\n\\n PgStat_Counter pgStatTransactionIdleTime = 0;\\n+PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\\n\\nNow, pgStatTransactionIdleTime is collecting just the Idle time so\\npgStatTransactionIdleTime should be renamed to \\\"pgStatIdleTime\\\" and\\npgStatTransactionIdleInTxnTime should be renamed to\\n\\\"pgStatTransactionIdleTime\\\"\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 15 Nov 2021 14:54:15 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n>\\n> On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> >\\n> > > It seems that in beentry->st_idle_time, you want to compute the\\n> > > STATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\n> > > means whenever it comes out of the\\n> > > STATE_IDLE, it will not enter inside this if check. You can run and\\n> > > test, I am sure that with this patch the \\\"idle_time\\\" will always\\n> > > remain 0.\\n> > >\\n> > Thank you Dilip for your time on this.\\n> > And yes you are right in both your observations.\\n> > Please find the attached patch for the updated version.\\n>\\n> Looks fine now except these variable names,\\n>\\n> PgStat_Counter pgStatTransactionIdleTime = 0;\\n> +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\\n>\\n> Now, pgStatTransactionIdleTime is collecting just the Idle time so\\n> pgStatTransactionIdleTime should be renamed to \\\"pgStatIdleTime\\\" and\\n> pgStatTransactionIdleInTxnTime should be renamed to\\n> \\\"pgStatTransactionIdleTime\\\"\\n>\\nGood point!\\nDone.\\n\\n\\n-- \\nRegards,\\nRafia Sabih\",\n \"msg_date\": \"Mon, 15 Nov 2021 12:15:46 +0100\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 15, 2021 at 4:46 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n>\\n> On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n> >\\n> > On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> > >\\n> > > > It seems that in beentry->st_idle_time, you want to compute the\\n> > > > STATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\n> > > > means whenever it comes out of the\\n> > > > STATE_IDLE, it will not enter inside this if check. You can run and\\n> > > > test, I am sure that with this patch the \\\"idle_time\\\" will always\\n> > > > remain 0.\\n> > > >\\n> > > Thank you Dilip for your time on this.\\n> > > And yes you are right in both your observations.\\n> > > Please find the attached patch for the updated version.\\n> >\\n> > Looks fine now except these variable names,\\n> >\\n> > PgStat_Counter pgStatTransactionIdleTime = 0;\\n> > +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\\n> >\\n> > Now, pgStatTransactionIdleTime is collecting just the Idle time so\\n> > pgStatTransactionIdleTime should be renamed to \\\"pgStatIdleTime\\\" and\\n> > pgStatTransactionIdleInTxnTime should be renamed to\\n> > \\\"pgStatTransactionIdleTime\\\"\\n> >\\n> Good point!\\n> Done.\\n\\n@@ -1018,7 +1019,7 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg,\\nTimestampTz now)\\n pgLastSessionReportTime = now;\\n tsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\\n tsmsg->m_active_time = pgStatActiveTime;\\n- tsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\\n+ tsmsg->m_idle_in_xact_time = pgStatIdleTime;\\n\\nI think this change is wrong, basically, \\\"tsmsg->m_idle_in_xact_time\\\"\\nis used for counting the database level idle in transaction count, you\\ncan check \\\"pg_stat_get_db_idle_in_transaction_time\\\" function for that.\\nSo \\\"pgStatTransactionIdleTime\\\" is the variable counting the idle in\\ntransaction time, pgStatIdleTime is just counting the idle time\\noutside the transaction so if we make this change we are changing the\\nmeaning of tsmsg->m_idle_in_xact_time.\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 15 Nov 2021 17:10:06 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Mon, 15 Nov 2021 at 12:40, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n>\\n> On Mon, Nov 15, 2021 at 4:46 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> >\\n> > On Mon, 15 Nov 2021 at 10:24, Dilip Kumar <dilipbalaut@gmail.com> wrote:\\n> > >\\n> > > On Wed, Nov 10, 2021 at 1:47 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> > > >\\n> > > > > It seems that in beentry->st_idle_time, you want to compute the\\n> > > > > STATE_IDLE, but that state is not handled in the outer \\\"if\\\", that\\n> > > > > means whenever it comes out of the\\n> > > > > STATE_IDLE, it will not enter inside this if check. You can run and\\n> > > > > test, I am sure that with this patch the \\\"idle_time\\\" will always\\n> > > > > remain 0.\\n> > > > >\\n> > > > Thank you Dilip for your time on this.\\n> > > > And yes you are right in both your observations.\\n> > > > Please find the attached patch for the updated version.\\n> > >\\n> > > Looks fine now except these variable names,\\n> > >\\n> > > PgStat_Counter pgStatTransactionIdleTime = 0;\\n> > > +PgStat_Counter pgStatTransactionIdleInTxnTime = 0;\\n> > >\\n> > > Now, pgStatTransactionIdleTime is collecting just the Idle time so\\n> > > pgStatTransactionIdleTime should be renamed to \\\"pgStatIdleTime\\\" and\\n> > > pgStatTransactionIdleInTxnTime should be renamed to\\n> > > \\\"pgStatTransactionIdleTime\\\"\\n> > >\\n> > Good point!\\n> > Done.\\n>\\n> @@ -1018,7 +1019,7 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg,\\n> TimestampTz now)\\n> pgLastSessionReportTime = now;\\n> tsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\\n> tsmsg->m_active_time = pgStatActiveTime;\\n> - tsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\\n> + tsmsg->m_idle_in_xact_time = pgStatIdleTime;\\n>\\n> I think this change is wrong, basically, \\\"tsmsg->m_idle_in_xact_time\\\"\\n> is used for counting the database level idle in transaction count, you\\n> can check \\\"pg_stat_get_db_idle_in_transaction_time\\\" function for that.\\n> So \\\"pgStatTransactionIdleTime\\\" is the variable counting the idle in\\n> transaction time, pgStatIdleTime is just counting the idle time\\n> outside the transaction so if we make this change we are changing the\\n> meaning of tsmsg->m_idle_in_xact_time.\\n\\nGot it.\\nUpdated\\n\\n-- \\nRegards,\\nRafia Sabih\",\n \"msg_date\": \"Tue, 16 Nov 2021 12:35:52 +0100\",\n \"msg_from\": \"Rafia Sabih <rafia.pghackers@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> > I think this change is wrong, basically, \\\"tsmsg->m_idle_in_xact_time\\\"\\n> > is used for counting the database level idle in transaction count, you\\n> > can check \\\"pg_stat_get_db_idle_in_transaction_time\\\" function for that.\\n> > So \\\"pgStatTransactionIdleTime\\\" is the variable counting the idle in\\n> > transaction time, pgStatIdleTime is just counting the idle time\\n> > outside the transaction so if we make this change we are changing the\\n> > meaning of tsmsg->m_idle_in_xact_time.\\n>\\n> Got it.\\n> Updated\\n\\nOkay, thanks, I will look into it one more time early next week and if\\nI see no issues then I will move it to RFC.\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 26 Nov 2021 13:57:28 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> Got it.\\n> Updated\\n\\nThanks for the patch. +1 for adding the idle/idle_in_txn_time/active\\ntime. I believe these are the total times a backend in its lifetime\\naccumulates. For instance, if a backend runs 100 txns, then these new\\ncolumns show the total time that the backend spent during these 100\\ntxns, right?\\n\\nFew comments on the patch:\\n\\n1) Patch is missing a commit message. It is good to have a commit\\nmessage describing the high-level of the feature.\\n2) This patch needs to bump the catalog version, at the end of the\\ncommit message, we usually keep a note \\\"Bump the catalog version\\\".\\n3) It looks like the documentation is missing [1], for the new columns.\\n4) When will these backend variables be reset? Is it at the backend\\nstartup? Or some other? If these variables are reset only at the\\nbackend startup and do they keep growing during the entire life of the\\nbackend process? If yes, what happens for a long running backend/user\\nsession, don't they get overflowed?\\n\\n+\\n+ int64 st_active_time;\\n+ int64 st_transaction_idle_time;\\n+ int64 st_idle_time;\\n } PgBackendStatus;\\n\\n5) Is there any way you can get them tested?\\n6) What will be entries of st_active_time, st_transaction_idle_time,\\nst_idle_time for non-backend processes, like bg writer, checkpointer,\\nparallel worker, bg worker, logical replication launcher, stats\\ncollector, sys logger etc?\\n\\n[1] https://www.postgresql.org/docs/devel/monitoring-stats.html#MONITORING-PG-STAT-ACTIVITY-VIEW\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Sat, 27 Nov 2021 08:00:13 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Sat, Nov 27, 2021 at 8:00 AM Bharath Rupireddy\\n<bharath.rupireddyforpostgres@gmail.com> wrote:\\n>\\n> On Tue, Nov 16, 2021 at 5:06 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> > Got it.\\n> > Updated\\n>\\n> Thanks for the patch. +1 for adding the idle/idle_in_txn_time/active\\n> time. I believe these are the total times a backend in its lifetime\\n> accumulates. For instance, if a backend runs 100 txns, then these new\\n> columns show the total time that the backend spent during these 100\\n> txns, right?\\n>\\n> Few comments on the patch:\\n>\\n> 1) Patch is missing a commit message. It is good to have a commit\\n> message describing the high-level of the feature.\\n> 2) This patch needs to bump the catalog version, at the end of the\\n> commit message, we usually keep a note \\\"Bump the catalog version\\\".\\n> 3) It looks like the documentation is missing [1], for the new columns.\\n> 4) When will these backend variables be reset? Is it at the backend\\n> startup? Or some other? If these variables are reset only at the\\n> backend startup and do they keep growing during the entire life of the\\n> backend process? If yes, what happens for a long running backend/user\\n> session, don't they get overflowed?\\n\\nThis is a 64-bit variable so I am not sure do we really need to worry\\nabout overflow? I mean if we are storing microseconds then also this\\nwill be able to last for ~300,000 years no?\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 11:32:44 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 1:53 PM Rafia Sabih <rafia.pghackers@gmail.com> wrote:\\n> To provide this information I was digging into how the statistics\\n> collector is working and found out there is already information like\\n> total time that a connection is active as well as idle computed in\\n> pgstat_report_activity[1]. Ideally, this would be the values we would\\n> like to see per process in pg_stat_activity.\\nIt's definitely useful to know how much time a backend has spent for\\nquery executions. Once you've this info, you can easily calculate the\\nidle time using this information: (now() - backend_start) -\\nactive_time. But, I'm wondering why you need to distinguish between\\nidle and idle in transactions - what's the usage? Either the backend\\nis doing some work or it sits idle. Another useful information would\\nbe when the last query execution was ended. From this information, you\\ncan figure out whether a backend is idle for a long time since the\\nlast execution and the execution time of the last query (query_end -\\nquery_start).\\n\\nYou also need to update the documentation.\\n\\n-- \\nThanks & Regards,\\nKuntal Ghosh\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Nov 2021 20:34:14 +0530\",\n \"msg_from\": \"Kuntal Ghosh <kuntalghosh.2007@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Mon, Nov 29, 2021 at 11:04 PM Kuntal Ghosh\\n<kuntalghosh.2007@gmail.com> wrote:\\n>\\n> You also need to update the documentation.\\n\\nYou also need to update rules.sql: https://cirrus-ci.com/task/6145265819189248\\n\\n\\n\",\n \"msg_date\": \"Wed, 12 Jan 2022 14:16:35 +0800\",\n \"msg_from\": \"Julien Rouhaud <rjuju123@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Wed, Jan 12, 2022 at 02:16:35PM +0800, Julien Rouhaud wrote:\\n> \\n> On Mon, Nov 29, 2021 at 11:04 PM Kuntal Ghosh\\n> <kuntalghosh.2007@gmail.com> wrote:\\n> >\\n> > You also need to update the documentation.\\n> \\n> You also need to update rules.sql: https://cirrus-ci.com/task/6145265819189248\\n\\nThere has been multiple comments in the last two months that weren't addressed\\nsince, and also the patch doesn't pass the regression tests anymore.\\n\\nRafia, do you plan to send a new version soon? Without update in the next few\\ndays this patch will be closed as Returned with Feedback, per the commitfest\\nrules.\\n\\n\\n\",\n \"msg_date\": \"Tue, 25 Jan 2022 22:22:45 +0800\",\n \"msg_from\": \"Julien Rouhaud <rjuju123@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello,\\n\\n> Without update in the next few\\n> days this patch will be closed as Returned with Feedback,\\n\\nThank you for the reminder, Julien.\\n\\nPer agreement with Rafia I have reworked the patch in the past days.\\nThe new version 6 is now ready for review.\\n\\nRegards,\\nSergey Dudoladov\",\n \"msg_date\": \"Thu, 27 Jan 2022 11:43:26 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\\n> \\n> Per agreement with Rafia I have reworked the patch in the past days.\\n> The new version 6 is now ready for review.\\n\\nGreat, thanks a lot Sergey!\\n\\nThe cfbot is happy with this new version:\\nhttps://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\\n\\n\\n\",\n \"msg_date\": \"Thu, 27 Jan 2022 20:36:56 +0800\",\n \"msg_from\": \"Julien Rouhaud <rjuju123@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi.\\n\\nAt Thu, 27 Jan 2022 20:36:56 +0800, Julien Rouhaud <rjuju123@gmail.com> wrote in\\n> On Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\\n> > \\n> > Per agreement with Rafia I have reworked the patch in the past days.\\n> > The new version 6 is now ready for review.\\n> \\n> Great, thanks a lot Sergey!\\n> \\n> The cfbot is happy with this new version:\\n> https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\\n\\nI think we can easily add the duration of the current state to the two\\nin pg_stat_get_activity and it would offer better information.\\n\\n\\n \\t\\tif (beentry->st_state == STATE_RUNNING ||\\n \\t\\t\\tbeentry->st_state == STATE_FASTPATH)\\n-\\t\\t\\tpgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n+\\t\\t{\\n+\\t\\t\\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\\n+\\t\\t\\tbeentry->st_total_active_time += usecs_diff;\\n+\\t\\t}\\n\\nThe two lines operates exactly the same way on variables with slightly\\ndifferent behavior. pgStatActiveTime is reported at transaction end\\nand reset at every tabstat reporting. st_total_active_time is reported\\nimmediately and reset at session end. Since we do the latter, the\\nfirst can be omitted by remembering the last values for the local\\nvariables at every reporting. This needs additional two exporting\\nfunction in pgstatfuncs like pgstat_get_my_queryid so others might\\nthink differently.\\n\\nThe write operation to beentry needs to be enclosed by\\nPGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\\nbetter to move that writes to the PGSTAT_WRITE_ACTIVITY section just\\nbelow.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Fri, 28 Jan 2022 14:36:31 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"At Mon, 29 Nov 2021 20:34:14 +0530, Kuntal Ghosh <kuntalghosh.2007@gmail.com> wrote in \\n> active_time. But, I'm wondering why you need to distinguish between\\n> idle and idle in transactions - what's the usage? Either the backend\\n> is doing some work or it sits idle. Another useful information would\\n\\nI believe many people suffer from mysterious long idle in\\ntransactions, which harm server performance many ways. In many cases\\ntransactions with unexpectedly long idle time is an omen or a cause of\\ntrouble.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Fri, 28 Jan 2022 14:40:24 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"At Fri, 28 Jan 2022 14:36:31 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in \\n> Hi.\\n> \\n> At Thu, 27 Jan 2022 20:36:56 +0800, Julien Rouhaud <rjuju123@gmail.com> wrote in\\n> > On Thu, Jan 27, 2022 at 11:43:26AM +0100, Sergey Dudoladov wrote:\\n> > > \\n> > > Per agreement with Rafia I have reworked the patch in the past days.\\n> > > The new version 6 is now ready for review.\\n> > \\n> > Great, thanks a lot Sergey!\\n> > \\n> > The cfbot is happy with this new version:\\n> > https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest/36/3405\\n> \\n> I think we can easily add the duration of the current state to the two\\n> in pg_stat_get_activity and it would offer better information.\\n> \\n> \\n> \\t\\tif (beentry->st_state == STATE_RUNNING ||\\n> \\t\\t\\tbeentry->st_state == STATE_FASTPATH)\\n> -\\t\\t\\tpgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n> +\\t\\t{\\n> +\\t\\t\\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\\n> +\\t\\t\\tbeentry->st_total_active_time += usecs_diff;\\n> +\\t\\t}\\n> \\n> The two lines operates exactly the same way on variables with slightly\\n> different behavior. pgStatActiveTime is reported at transaction end\\n> and reset at every tabstat reporting. st_total_active_time is reported\\n> immediately and reset at session end. Since we do the latter, the\\n\\n> first can be omitted by remembering the last values for the local\\n> variables at every reporting. This needs additional two exporting\\n\\nOf course it's typo(?) of \\\"values of the shared variables\\\".\\nSorry for the mistake.\\n\\n> function in pgstatfuncs like pgstat_get_my_queryid so others might\\n> think differently.\\n> \\n> The write operation to beentry needs to be enclosed by\\n> PGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\\n> better to move that writes to the PGSTAT_WRITE_ACTIVITY section just\\n> below.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Fri, 28 Jan 2022 14:43:03 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nThank you for the reviews.\\n\\n> > The write operation to beentry needs to be enclosed by\\n> > PGSTAT_BEGIN/END_WRITE_ACTIVITY(). In that perspective, it would be\\n> > better to move that writes to the PGSTAT_WRITE_ACTIVITY section just\\n> > below.\\n\\nI have fixed it in the new version.\\n\\n> > if (beentry->st_state == STATE_RUNNING ||\\n> > beentry->st_state == STATE_FASTPATH)\\n> > - pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n> > + {\\n> > + pgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\\n> > + beentry->st_total_active_time += usecs_diff;\\n> > + }\\n> >\\n> > The two lines operates exactly the same way on variables with slightly\\n> > different behavior. pgStatActiveTime is reported at transaction end\\n> > and reset at every tabstat reporting. st_total_active_time is reported\\n> > immediately and reset at session end. Since we do the latter, the\\n> > first can be omitted by remembering the last values for the local\\n> > variables at every reporting. This needs additional two exporting\\n>\\n> Of course it's typo(?) of \\\"values of the shared variables\\\".\\n\\nCould you please elaborate on this idea ?\\nSo we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\\nused to report respective metrics in pg_stat_database.\\nNow beentry's st_total_active_time / st_total_transaction_idle_time\\nduplicates this info, so one may get rid of pgStat*Time counters. Is\\nthe idea to report instead of them at every tabstat reporting the\\ndifference between the last memorized value of st_total_*_time and\\nits current value ?\\n\\n> > This needs additional two exporting\\n> > function in pgstatfuncs like pgstat_get_my_queryid so others might\\n> > think differently.\\n\\nWhat would be example functions to look at ?\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Mon, 31 Jan 2022 15:11:56 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"At Mon, 31 Jan 2022 15:11:56 +0100, Sergey Dudoladov <sergey.dudoladov@gmail.com> wrote in \\n> > > if (beentry->st_state == STATE_RUNNING ||\\n> > > beentry->st_state == STATE_FASTPATH)\\n> > > - pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);\\n> > > + {\\n> > > + pgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\\n> > > + beentry->st_total_active_time += usecs_diff;\\n> > > + }\\n> > >\\n> > > The two lines operates exactly the same way on variables with slightly\\n> > > different behavior. pgStatActiveTime is reported at transaction end\\n> > > and reset at every tabstat reporting. st_total_active_time is reported\\n> > > immediately and reset at session end. Since we do the latter, the\\n> > > first can be omitted by remembering the last values for the local\\n> > > variables at every reporting. This needs additional two exporting\\n> >\\n> > Of course it's typo(?) of \\\"values of the shared variables\\\".\\n> \\n> Could you please elaborate on this idea ?\\n> So we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\\n> used to report respective metrics in pg_stat_database.\\n> Now beentry's st_total_active_time / st_total_transaction_idle_time\\n> duplicates this info, so one may get rid of pgStat*Time counters. Is\\n> the idea to report instead of them at every tabstat reporting the\\n> difference between the last memorized value of st_total_*_time and\\n> its current value ?\\n\\nExactly. The attached first diff is the schetch of that.\\n\\n> > > This needs additional two exporting\\n> > > function in pgstatfuncs like pgstat_get_my_queryid so others might\\n> > > think differently.\\n> \\n> What would be example functions to look at ?\\n\\npgstat_get_my_queryid..\\n\\n\\nAnd, it seems like I forgot to mention this, but as Kuntal suggested\\n(in a different context and objective, though) upthraed, I think that\\nwe can show realtime values in the two time fields by adding the time\\nof the current state. See the attached second diff.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\ndiff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c\\nindex 0646f53098..27419c1851 100644\\n--- a/src/backend/postmaster/pgstat.c\\n+++ b/src/backend/postmaster/pgstat.c\\n@@ -249,8 +249,8 @@ static int\\tpgStatXactRollback = 0;\\n PgStat_Counter pgStatBlockReadTime = 0;\\n PgStat_Counter pgStatBlockWriteTime = 0;\\n static PgStat_Counter pgLastSessionReportTime = 0;\\n-PgStat_Counter pgStatActiveTime = 0;\\n-PgStat_Counter pgStatTransactionIdleTime = 0;\\n+PgStat_Counter pgStatLastActiveTime = 0;\\n+PgStat_Counter pgStatLastTransactionIdleTime = 0;\\n SessionEndType pgStatSessionEndCause = DISCONNECT_NORMAL;\\n \\n /* Record that's written to 2PC state file when pgstat state is persisted */\\n@@ -1026,8 +1026,13 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg, TimestampTz now)\\n \\t\\t\\tTimestampDifference(pgLastSessionReportTime, now, &secs, &usecs);\\n \\t\\t\\tpgLastSessionReportTime = now;\\n \\t\\t\\ttsmsg->m_session_time = (PgStat_Counter) secs * 1000000 + usecs;\\n-\\t\\t\\ttsmsg->m_active_time = pgStatActiveTime;\\n-\\t\\t\\ttsmsg->m_idle_in_xact_time = pgStatTransactionIdleTime;\\n+\\n+\\t\\t\\t/* send the difference since the last report */\\n+\\t\\t\\ttsmsg->m_active_time =\\n+\\t\\t\\t\\tpgstat_get_my_active_time() - pgStatLastActiveTime;\\n+\\t\\t\\ttsmsg->m_idle_in_xact_time =\\n+\\t\\t\\t\\tpgstat_get_my_transaction_idle_time() -\\n+\\t\\t\\t\\tpgStatLastTransactionIdleTime;\\n \\t\\t}\\n \\t\\telse\\n \\t\\t{\\n@@ -1039,8 +1044,8 @@ pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg, TimestampTz now)\\n \\t\\tpgStatXactRollback = 0;\\n \\t\\tpgStatBlockReadTime = 0;\\n \\t\\tpgStatBlockWriteTime = 0;\\n-\\t\\tpgStatActiveTime = 0;\\n-\\t\\tpgStatTransactionIdleTime = 0;\\n+\\t\\tpgStatLastActiveTime = pgstat_get_my_active_time();\\n+\\t\\tpgStatLastTransactionIdleTime = pgstat_get_my_transaction_idle_time();\\n \\t}\\n \\telse\\n \\t{\\ndiff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c\\nindex 5f15dcdc05..8b6836a662 100644\\n--- a/src/backend/utils/activity/backend_status.c\\n+++ b/src/backend/utils/activity/backend_status.c\\n@@ -613,15 +613,9 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\\n \\t\\t */\\n \\t\\tif (beentry->st_state == STATE_RUNNING ||\\n \\t\\t\\tbeentry->st_state == STATE_FASTPATH)\\n-\\t\\t{\\n-\\t\\t\\tpgstat_count_conn_active_time((PgStat_Counter) usecs_diff);\\n \\t\\t\\tactive_time_diff = usecs_diff;\\n-\\t\\t}\\n \\t\\telse\\n-\\t\\t{\\n-\\t\\t\\tpgstat_count_conn_txn_idle_time((PgStat_Counter) usecs_diff);\\n \\t\\t\\ttransaction_idle_time_diff = usecs_diff;\\n-\\t\\t}\\n \\t}\\n \\n \\t/*\\n@@ -1078,6 +1072,48 @@ pgstat_get_my_query_id(void)\\n }\\n \\n \\n+/* ----------\\n+ * pgstat_get_my_active_time() -\\n+ *\\n+ * Return current backend's accumulated active time.\\n+ */\\n+uint64\\n+pgstat_get_my_active_time(void)\\n+{\\n+\\tif (!MyBEEntry)\\n+\\t\\treturn 0;\\n+\\n+\\t/*\\n+\\t * There's no need for a lock around pgstat_begin_read_activity /\\n+\\t * pgstat_end_read_activity here as it's only called from\\n+\\t * pg_stat_get_activity which is already protected, or from the same\\n+\\t * backend which means that there won't be concurrent writes.\\n+\\t */\\n+\\treturn MyBEEntry->st_total_active_time;\\n+}\\n+\\n+\\n+/* ----------\\n+ * pgstat_get_my_transaction_idle_time() -\\n+ *\\n+ * Return current backend's accumulated in-transaction idel time.\\n+ */\\n+uint64\\n+pgstat_get_my_transaction_idle_time(void)\\n+{\\n+\\tif (!MyBEEntry)\\n+\\t\\treturn 0;\\n+\\n+\\t/*\\n+\\t * There's no need for a lock around pgstat_begin_read_activity /\\n+\\t * pgstat_end_read_activity here as it's only called from\\n+\\t * pg_stat_get_activity which is already protected, or from the same\\n+\\t * backend which means that there won't be concurrent writes.\\n+\\t */\\n+\\treturn MyBEEntry->st_total_transaction_idle_time;\\n+}\\n+\\n+\\n /* ----------\\n * pgstat_fetch_stat_beentry() -\\n *\\ndiff --git a/src/include/pgstat.h b/src/include/pgstat.h\\nindex e10d20222a..382d7202c1 100644\\n--- a/src/include/pgstat.h\\n+++ b/src/include/pgstat.h\\n@@ -1185,10 +1185,6 @@ extern void pgstat_initstats(Relation rel);\\n \\t(pgStatBlockReadTime += (n))\\n #define pgstat_count_buffer_write_time(n)\\t\\t\\t\\t\\t\\t\\t\\\\\\n \\t(pgStatBlockWriteTime += (n))\\n-#define pgstat_count_conn_active_time(n)\\t\\t\\t\\t\\t\\t\\t\\\\\\n-\\t(pgStatActiveTime += (n))\\n-#define pgstat_count_conn_txn_idle_time(n)\\t\\t\\t\\t\\t\\t\\t\\\\\\n-\\t(pgStatTransactionIdleTime += (n))\\n \\n extern void pgstat_count_heap_insert(Relation rel, PgStat_Counter n);\\n extern void pgstat_count_heap_update(Relation rel, bool hot);\\ndiff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h\\nindex 96d432ce49..1791dd6842 100644\\n--- a/src/include/utils/backend_status.h\\n+++ b/src/include/utils/backend_status.h\\n@@ -309,6 +309,8 @@ extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);\\n extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,\\n \\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t int buflen);\\n extern uint64 pgstat_get_my_query_id(void);\\n+extern uint64 pgstat_get_my_active_time(void);\\n+extern uint64 pgstat_get_my_transaction_idle_time(void);\\n \\n \\n /* ----------\\n\\ndiff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c\\nindex 8b6836a662..996f4e88d7 100644\\n--- a/src/backend/utils/activity/backend_status.c\\n+++ b/src/backend/utils/activity/backend_status.c\\n@@ -587,10 +587,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\\n \\t * If the state has changed from \\\"active\\\" or \\\"idle in transaction\\\",\\n \\t * calculate the duration.\\n \\t */\\n-\\tif ((beentry->st_state == STATE_RUNNING ||\\n-\\t\\t beentry->st_state == STATE_FASTPATH ||\\n-\\t\\t beentry->st_state == STATE_IDLEINTRANSACTION ||\\n-\\t\\t beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&\\n+\\tif ((PGSTAT_IS_ACTIVE(beentry) || PGSTAT_IS_IDLEINTRANSACTION(beentry)) &&\\n \\t\\tstate != beentry->st_state)\\n \\t{\\n \\t\\tlong\\t\\tsecs;\\n@@ -611,8 +608,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)\\n \\t\\t * 2. The latter values are reset to 0 once the data has been sent\\n \\t\\t * to the statistics collector.\\n \\t\\t */\\n-\\t\\tif (beentry->st_state == STATE_RUNNING ||\\n-\\t\\t\\tbeentry->st_state == STATE_FASTPATH)\\n+\\t\\tif (PGSTAT_IS_ACTIVE(beentry))\\n \\t\\t\\tactive_time_diff = usecs_diff;\\n \\t\\telse\\n \\t\\t\\ttransaction_idle_time_diff = usecs_diff;\\ndiff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c\\nindex 7c2776c14c..48c0ffa33a 100644\\n--- a/src/backend/utils/adt/pgstatfuncs.c\\n+++ b/src/backend/utils/adt/pgstatfuncs.c\\n@@ -675,6 +675,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\\n \\t\\t{\\n \\t\\t\\tSockAddr\\tzero_clientaddr;\\n \\t\\t\\tchar\\t *clipped_activity;\\n+\\t\\t\\tint64\\t\\ttmp_time;\\n \\n \\t\\t\\tswitch (beentry->st_state)\\n \\t\\t\\t{\\n@@ -917,9 +918,25 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\\n \\t\\t\\telse\\n \\t\\t\\t\\tvalues[29] = UInt64GetDatum(beentry->st_query_id);\\n \\n-\\t\\t\\t/* convert to msec for display */\\n-\\t\\t\\tvalues[30] = Float8GetDatum(beentry->st_total_active_time / 1000.0) ;\\n-\\t\\t\\tvalues[31] = Float8GetDatum(beentry->st_total_transaction_idle_time / 1000.0);\\n+\\t\\t\\ttmp_time = beentry->st_total_active_time;\\n+\\n+\\t\\t\\t/* add the realtime value to the counter if needed */\\n+\\t\\t\\tif (PGSTAT_IS_ACTIVE(beentry))\\n+\\t\\t\\t\\ttmp_time +=\\n+\\t\\t\\t\\t\\tGetCurrentTimestamp() - beentry->st_state_start_timestamp;\\n+\\n+\\t\\t\\t/* convert it to msec */\\n+\\t\\t\\tvalues[30] = Float8GetDatum(tmp_time / 1000.0) ;\\n+\\n+\\t\\t\\ttmp_time = beentry->st_total_transaction_idle_time;\\n+\\n+\\t\\t\\t/* add the realtime value to the counter if needed */\\n+\\t\\t\\tif (PGSTAT_IS_IDLEINTRANSACTION(beentry))\\n+\\t\\t\\t\\ttmp_time +=\\n+\\t\\t\\t\\t\\tGetCurrentTimestamp() - beentry->st_state_start_timestamp;\\n+\\n+\\t\\t\\t/* convert it to msec */\\n+\\t\\t\\tvalues[31] = Float8GetDatum(tmp_time);\\n \\t\\t}\\n \\t\\telse\\n \\t\\t{\\ndiff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h\\nindex 1791dd6842..a03225c4f0 100644\\n--- a/src/include/utils/backend_status.h\\n+++ b/src/include/utils/backend_status.h\\n@@ -235,6 +235,12 @@ typedef struct PgBackendStatus\\n \\t((before_changecount) == (after_changecount) && \\\\\\n \\t ((before_changecount) & 1) == 0)\\n \\n+/* macros to identify the states for time accounting */\\n+#define PGSTAT_IS_ACTIVE(s)\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\\\\\n+\\t((s)->st_state == STATE_RUNNING || (s)->st_state == STATE_FASTPATH)\\n+#define PGSTAT_IS_IDLEINTRANSACTION(s)\\t\\t\\t \\\\\\n+\\t((s)->st_state == STATE_IDLEINTRANSACTION ||\\t\\t\\\\\\n+\\t (s)->st_state == STATE_IDLEINTRANSACTION_ABORTED)\\n \\n /* ----------\\n * LocalPgBackendStatus\",\n \"msg_date\": \"Tue, 01 Feb 2022 13:55:16 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\n> > Could you please elaborate on this idea ?\\n> > So we have pgStatActiveTime and pgStatIdleInTransactionTime ultimately\\n> > used to report respective metrics in pg_stat_database.\\n> > Now beentry's st_total_active_time / st_total_transaction_idle_time\\n> > duplicates this info, so one may get rid of pgStat*Time counters. Is\\n> > the idea to report instead of them at every tabstat reporting the\\n> > difference between the last memorized value of st_total_*_time and\\n> > its current value ?\\n>\\n> Exactly. The attached first diff is the schetch of that.\\n\\nThis diff actually adds more code than it removes and somewhat bloats the patch.\\nI decided to incorporate it anyway because the diff explicitly shows\\nthat time differences since the last report\\nare send to the statistics collector,which is not immediately evident\\nfrom the existing PgStat*Time counters.\\nThat point may be worth further discussion though.\\n\\n\\n> And, it seems like I forgot to mention this, but as Kuntal suggested\\n> (in a different context and objective, though) upthraed, I think that\\n> we can show realtime values in the two time fields by adding the time\\n> of the current state. See the attached second diff.\\n\\nThat is exactly what we need in our infra, also included into the patch.\\n\\n\\n@Kyotaro Horiguchi\\nThank you for the contribution. I included both of your diffs with\\nminor changes.\\nShould I add you to the authors of the patch given that now half of it\\nis basically your code ?\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Fri, 4 Feb 2022 10:58:24 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-02-04 10:58:24 +0100, Sergey Dudoladov wrote:\\n> Thank you for the contribution. I included both of your diffs with\\n> minor changes.\\n\\nThis currently doesn't apply: http://cfbot.cputube.org/patch_37_3405.log\\n\\nCould you rebase? Marking as waiting on author for now.\\n\\n- Andres\\n\\n\\n\",\n \"msg_date\": \"Mon, 21 Mar 2022 17:13:35 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello,\\n\\nI've updated the patch in preparation for the upcoming commitfest.\\n\\nRegards,\\nSergey.\",\n \"msg_date\": \"Mon, 13 Jun 2022 16:51:00 +0200\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 6/13/22 4:51 PM, Sergey Dudoladov wrote:\\n> Hello,\\n>\\n> I've updated the patch in preparation for the upcoming commitfest.\\n\\nI really like the idea of adding additional information like the ones in \\nthis patch, so +1 for the patch.\\n\\nAs far the patch:\\n\\n@@ -864,7 +864,9 @@ CREATE VIEW pg_stat_activity AS\\n s.backend_xmin,\\n S.query_id,\\n S.query,\\n- S.backend_type\\n+ S.backend_type,\\n+ S.active_time,\\n+ S.idle_in_transaction_time\\n\\nwhat about using total_active_time and total_idle_in_transaction_time?\\n\\nI think that would avoid any confusion and \\\"total_\\\" is also already used \\nin other pg_stat_* views when appropriate.\\n\\n@@ -468,6 +468,13 @@ pgstat_beshutdown_hook(int code, Datum arg)\\n\\n beentry->st_procpid = 0; /* mark invalid */\\n\\n+ /*\\n+ * Reset per-backend counters so that accumulated values for the \\ncurrent\\n+ * backend are not used for future backends.\\n+ */\\n+ beentry->st_total_active_time = 0;\\n+ beentry->st_total_transaction_idle_time = 0;\\n\\nshouldn't that be in pgstat_bestart() instead? (and just let \\npgstat_beshutdown_hook() set st_procpid to 0)\\n\\n /* so that functions can check if backend_status.c is up via \\nMyBEEntry */\\n@@ -524,6 +531,8 @@ pgstat_report_activity(BackendState state, const \\nchar *cmd_str)\\n TimestampTz start_timestamp;\\n TimestampTz current_timestamp;\\n int len = 0;\\n+ int64 active_time_diff = 0;\\n+ int64 transaction_idle_time_diff = 0;\\n\\nI think here we can use only a single variable say \\\"state_time_diff\\\" for \\nexample, as later only one of those two is incremented anyway.\\n\\n+++ b/src/backend/utils/adt/pgstatfuncs.c\\n@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)\\n Datum\\n pg_stat_get_activity(PG_FUNCTION_ARGS)\\n {\\n-#define PG_STAT_GET_ACTIVITY_COLS 30\\n+#define PG_STAT_GET_ACTIVITY_COLS 32\\n int num_backends = \\npgstat_fetch_stat_numbackends();\\n int curr_backend;\\n int pid = PG_ARGISNULL(0) ? -1 : \\nPG_GETARG_INT32(0);\\n@@ -621,6 +621,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)\\n {\\n SockAddr zero_clientaddr;\\n char *clipped_activity;\\n+ int64 time_to_report;\\n\\nwhat about total_time_to_report instead?\\n\\nAlso, maybe not for this patch but I think that would be also useful to \\nget the total time waited (so that we would get more inside of what the \\n\\\"active\\\" time was made of).\\n\\nRegards,\\n\\n-- \\n\\nBertrand Drouvot\\nAmazon Web Services:https://aws.amazon.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 4 Jul 2022 18:29:13 +0200\",\n \"msg_from\": \"\\\"Drouvot, Bertrand\\\" <bdrouvot@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello,\\n\\nthanks for the helpful review. I have incorporated most of the\\nsuggestions into the patch. I have also rebased and tested the patch\\non top of the current master (2cd2569c72b89200).\\n\\n> + int64 active_time_diff = 0;\\n> + int64 transaction_idle_time_diff = 0;\\n>\\n> I think here we can use only a single variable say \\\"state_time_diff\\\" for\\n> example, as later only one of those two is incremented anyway.\\n\\nI have written it this way to avoid cluttering the critical section\\nbetween PGSTAT_(BEGIN|END)_WRITE_ACTIVITY.\\nWith two variable one can leave only actual increments in the section\\nand check conditions / call TimestampDifference outside of it.\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Mon, 11 Jul 2022 16:43:12 +0200\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Rafia, Sergey,\\n\\nMany thanks for working on this!\\n\\n> I have incorporated most of the suggestions into the patch. I have also rebased and tested the patch on top of the current master\\n\\nI noticed that this patch is marked as \\\"Needs Review\\\" and decided to\\ntake a look.\\n\\nI believe there is a bug in the implementation. Here is what I did:\\n\\n```\\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n...\\ntotal_active_time | 9.128\\ntotal_idle_in_transaction_time | 0\\n\\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n...\\ntotal_active_time | 10.626\\ntotal_idle_in_transaction_time | 0\\n\\n57033 (master) =# BEGIN;\\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n...\\ntotal_active_time | 17.443\\ntotal_idle_in_transaction_time | 2314.703\\n\\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n...\\ntotal_active_time | 2514.635\\ntotal_idle_in_transaction_time | 2314.703\\n\\n57033 (master) =# COMMIT;\\n57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n...\\ntotal_active_time | 22.048\\ntotal_idle_in_transaction_time | 7300.911\\n```\\n\\nSo it looks like total_active_time tracks seconds when a user executes\\nsingle expressions and milliseconds when running a transaction. It\\nshould always track milliseconds.\\n\\nPlease use `git format-patch` for the next patch and provide a commit\\nmessage, as it was previously pointed out by Bharath. Please specify\\nthe list of the authors and reviewers and add a note about\\nincrementing the catalog version.\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Wed, 13 Jul 2022 11:56:44 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi again,\\n\\n> 57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n> ...\\n> total_active_time | 2514.635\\n> total_idle_in_transaction_time | 2314.703\\n>\\n> 57033 (master) =# COMMIT;\\n> 57033 (master) =# select * from pg_stat_activity where pid = 57033;\\n> ...\\n> total_active_time | 22.048\\n> total_idle_in_transaction_time | 7300.911\\n> ```\\n\\nMy previous message was wrong, total_active_time doesn't track\\nseconds. I got confused by the name of this column. Still I'm pretty\\nconfident it shouldn't decrease.\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Wed, 13 Jul 2022 12:09:13 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Rafia, Sergey,\\n\\n+1 for adding the total_active_time and total_idle_in_transaction_time \\nto pg_stat_activity.\\n\\nI reviewed the patch and here are some comments.\\n\\n+ <entry role=\\\"catalog_table_entry\\\"><para role=\\\"column_definition\\\">\\n+ <structfield>total_active_time</structfield> <type>double \\nprecision</type>\\n+ </para>\\n+ <para>\\n+ Time in milliseconds this backend spent in \\n<literal>active</literal> and\\n+ <literal>fastpath</literal> states.\\n\\nIs 'fastpath' an abbreviation of 'fastpath function call'?\\nIf so, I feel it's clearer '<literal>fastpath function call</literal>' \\nthan '<literal>fastpath</literal>'.\\n\\n\\n+extern uint64 pgstat_get_my_active_time(void);\\n+extern uint64 pgstat_get_my_transaction_idle_time(void);\\n\\nAre these functions necessary?\\nIt seems they are not called from anywhere, doesn't it?\\n\\n-- \\nRegards,\\n\\n--\\nAtsushi Torikoshi\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Jul 2022 12:15:24 +0900\",\n \"msg_from\": \"torikoshia <torikoshia@oss.nttdata.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello,\\n\\nI have addressed the reviews.\\n\\n@Aleksander Alekseev thanks for reporting the issue. I have altered\\nthe patch to respect the behavior of pg_stat_activity, specifically\\n[1]\\n\\n> Another important point is that when a server process is asked to display any of these statistics,\\n> it first fetches the most recent report emitted by the collector process and then continues to use this snapshot\\n> for all statistical views and functions until the end of its current transaction.\\n> So the statistics will show static information as long as you continue the current transaction.\\n\\nFor the patch it means no computing of real-time values of\\ntotal_*_time. Here is an example to illustrate the new behavior:\\n\\n=# begin;\\n\\n=*# select total_active_time, total_idle_in_transaction_time from\\npg_stat_activity where pid = pg_backend_pid();\\n total_active_time | total_idle_in_transaction_time\\n-------------------+--------------------------------\\n 0.124 | 10505.098\\n\\npostgres=*# select pg_sleep(10);\\n\\npostgres=*# select total_active_time, total_idle_in_transaction_time\\nfrom pg_stat_activity where pid = pg_backend_pid();\\n total_active_time | total_idle_in_transaction_time\\n-------------------+--------------------------------\\n 0.124 | 10505.098\\n\\npostgres=*# commit;\\n\\npostgres=# select total_active_time, total_idle_in_transaction_time\\nfrom pg_stat_activity where pid = pg_backend_pid();\\n total_active_time | total_idle_in_transaction_time\\n-------------------+--------------------------------\\n 10015.796 | 29322.831\\n\\n\\n[1] https://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWS\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Thu, 21 Jul 2022 18:22:51 +0200\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi Sergey,\\n\\n> @Aleksander Alekseev thanks for reporting the issue. I have altered\\n> the patch to respect the behavior of pg_stat_activity, specifically\\n> [1]\\n>\\n> > Another important point is that when a server process is asked to\\ndisplay any of these statistics,\\n> > it first fetches the most recent report emitted by the collector\\nprocess and then continues to use this snapshot\\n> > for all statistical views and functions until the end of its current\\ntransaction.\\n> > So the statistics will show static information as long as you continue\\nthe current transaction.\\n>\\n> For the patch it means no computing of real-time values of\\n> total_*_time. Here is an example to illustrate the new behavior:\\n>\\n> =# begin;\\n>\\n> =*# select total_active_time, total_idle_in_transaction_time from\\n> pg_stat_activity where pid = pg_backend_pid();\\n> total_active_time | total_idle_in_transaction_time\\n> -------------------+--------------------------------\\n> 0.124 | 10505.098\\n>\\n> postgres=*# select pg_sleep(10);\\n>\\n> postgres=*# select total_active_time, total_idle_in_transaction_time\\n> from pg_stat_activity where pid = pg_backend_pid();\\n> total_active_time | total_idle_in_transaction_time\\n> -------------------+--------------------------------\\n> 0.124 | 10505.098\\n>\\n> postgres=*# commit;\\n>\\n> postgres=# select total_active_time, total_idle_in_transaction_time\\n> from pg_stat_activity where pid = pg_backend_pid();\\n> total_active_time | total_idle_in_transaction_time\\n> -------------------+--------------------------------\\n> 10015.796 | 29322.831\\n>\\n>\\n> [1]\\nhttps://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWS\\n\\nThis looks reasonable.\\n\\nWhat concerns me though is the fact that total_idle_in_transaction_time for\\ngiven session doesn't seem to updated from the perspective of another\\nsession:\\n\\n```\\nsession1 (78376) =# BEGIN;\\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\\n...\\ntotal_active_time | 40.057\\ntotal_idle_in_transaction_time | 34322.171\\n\\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\\n...\\ntotal_active_time | 40.057\\ntotal_idle_in_transaction_time | 34322.171\\n\\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\\n...\\ntotal_active_time | 46.908\\ntotal_idle_in_transaction_time | 96933.518\\n\\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\\n...\\ntotal_active_time | 46.908\\ntotal_idle_in_transaction_time | 96933.518 <--- doesn't change!\\n\\nsession1 (78376) =# COMMIT;\\nsession1 (78376) =# select * from pg_stat_activity where pid = 78376;\\n...\\ntotal_active_time | 47.16\\ntotal_idle_in_transaction_time | 218422.143\\n\\nsession2 (78382) =# select * from pg_stat_activity where pid = 78376;\\ntotal_active_time | 50.631\\ntotal_idle_in_transaction_time | 218422.143\\n```\\n\\nThis is consistent with the current documentation:\\n\\n> Each individual server process transmits new statistical counts to the\\ncollector just before going idle; so a query or transaction still in\\nprogress does not affect the displayed totals.\\n\\nBut it makes me wonder if there will be a lot of use of\\ntotal_idle_in_transaction_time and if the patch should actually alter this\\nbehavior.\\n\\nThoughts?\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\nHi Sergey,> @Aleksander Alekseev thanks for reporting the issue. I have altered> the patch to respect the behavior of pg_stat_activity, specifically> [1]>> > Another important point is that when a server process is asked to display any of these statistics,> > it first fetches the most recent report emitted by the collector process and then continues to use this snapshot> > for all statistical views and functions until the end of its current transaction.> > So the statistics will show static information as long as you continue the current transaction.>> For the patch it means no computing of real-time values of> total_*_time. Here is an example to illustrate the new behavior:>> =# begin;>> =*# select total_active_time, total_idle_in_transaction_time from> pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 0.124 | 10505.098>> postgres=*# select pg_sleep(10);>> postgres=*# select total_active_time, total_idle_in_transaction_time> from pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 0.124 | 10505.098>> postgres=*# commit;>> postgres=# select total_active_time, total_idle_in_transaction_time> from pg_stat_activity where pid = pg_backend_pid();> total_active_time | total_idle_in_transaction_time> -------------------+--------------------------------> 10015.796 | 29322.831>>> [1] https://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-STATS-VIEWSThis looks reasonable.What concerns me though is the fact that total_idle_in_transaction_time for given session doesn't seem to updated from the perspective of another session:```session1 (78376) =# BEGIN;session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 40.057total_idle_in_transaction_time | 34322.171session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 40.057total_idle_in_transaction_time | 34322.171session2 (78382) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 46.908total_idle_in_transaction_time | 96933.518session2 (78382) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 46.908total_idle_in_transaction_time | 96933.518 <--- doesn't change!session1 (78376) =# COMMIT;session1 (78376) =# select * from pg_stat_activity where pid = 78376;...total_active_time | 47.16total_idle_in_transaction_time | 218422.143session2 (78382) =# select * from pg_stat_activity where pid = 78376;total_active_time | 50.631total_idle_in_transaction_time | 218422.143```This is consistent with the current documentation:> Each individual server process transmits new statistical counts to the collector just before going idle; so a query or transaction still in progress does not affect the displayed totals.But it makes me wonder if there will be a lot of use of total_idle_in_transaction_time and if the patch should actually alter this behavior.Thoughts?-- Best regards,Aleksander Alekseev\",\n \"msg_date\": \"Fri, 22 Jul 2022 11:32:09 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi hackers,\\n\\nAll in all the patch seems to be in good shape.\\n\\n> This is consistent with the current documentation:\\n>\\n> > Each individual server process transmits new statistical counts to the collector just before going idle; so a query or transaction still in progress does not affect the displayed totals.\\n>\\n> But it makes me wonder if there will be a lot of use of total_idle_in_transaction_time and if the patch should actually alter this behavior.\\n>\\n> Thoughts?\\n\\nOn second thought, this is arguably out of scope of this particular\\npatch and this particular discussion. In any case, having some stats\\nis better than none.\\n\\nI'm going to change the status of the patch to \\\"Ready for Committer\\\"\\nin a short time unless anyone has a second opinion.\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Jul 2022 12:42:20 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello hackers,\\n\\nIs there anything we can do to facilitate merging of this patch ?\\nIt has been in the \\\"ready-for-commiter\\\" state for 3 commitfests in a row now.\\n\\nWe would appreciate if the patch makes it to version 16: the need to\\nmonitor idle-in-transaction connections is very real for us.\\n\\nRegards,\\nSergey Dudoladov\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Nov 2022 19:11:43 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-07-21 18:22:51 +0200, Sergey Dudoladov wrote:\\n> From b5298301a3f5223bd78c519ddcddbd1bec9cf000 Mon Sep 17 00:00:00 2001\\n> From: Sergey Dudoladov <sergey.dudoladov@gmail.com>\\n> Date: Wed, 20 Apr 2022 23:47:37 +0200\\n> Subject: [PATCH] pg_stat_activity: add 'total_active_time' and\\n> 'total_idle_in_transaction_time'\\n> \\n> catversion bump because of the change in the contents of pg_stat_activity\\n> \\n> Author: Sergey Dudoladov, based on the initial version by Rafia Sabih\\n> \\n> Reviewed-by: Aleksander Alekseev, Bertrand Drouvot, and Atsushi Torikoshi\\n> \\n> Discussion: https://www.postgresql.org/message-id/flat/CA%2BFpmFcJF0vwi-SWW0wYO-c-FbhyawLq4tCpRDCJJ8Bq%3Dja-gA%40mail.gmail.com\\n\\nIsn't this patch breaking pg_stat_database? You removed\\npgstat_count_conn_active_time() etc and the declaration for pgStatActiveTime /\\npgStatTransactionIdleTime (but left the definition in pgstat_database.c), but\\ndidn't replace it with anything afaics.\\n\\n\\nSeparately from that, I'm a bit worried about starting to add accumulative\\ncounters to pg_stat_activity. It's already gotten hard to use interactively\\ndue to the number of columns - and why stop with the columns you suggest? Why\\nnot show e.g. the total number of reads/writes, tuples inserted / deleted,\\netc. as well?\\n\\nI wonder if we shouldn't add a pg_stat_session or such for per-connection\\ncounters that show not the current state, but accumulated per-session state.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Nov 2022 17:56:14 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 8, 2022 at 6:56 PM Andres Freund <andres@anarazel.de> wrote:\\n\\n>\\n> Separately from that, I'm a bit worried about starting to add accumulative\\n> counters to pg_stat_activity. It's already gotten hard to use interactively\\n> due to the number of columns - and why stop with the columns you suggest?\\n> Why\\n> not show e.g. the total number of reads/writes, tuples inserted / deleted,\\n> etc. as well?\\n>\\n> I wonder if we shouldn't add a pg_stat_session or such for per-connection\\n> counters that show not the current state, but accumulated per-session\\n> state.\\n>\\n>\\nI would much rather go down this route than make the existing table wider.\\n\\npg_stat_activity_state_duration (this patch) [the table - for a given\\nbackend - would be empty if track_activities is off]\\npg_stat_activity_bandwidth_usage (if someone feels like implementing the\\nother items you mention)\\n\\n\\nI'm not really buying into the idea of having multiple states sum their\\ntimes together. I would expect one column per state. Actually two,\\nbecause I also suggest that not only is the duration recorded, but a\\ncounter be incremented each time a given state becomes the currently active\\nstate. Seems like having access to a divisor of some form may be useful.\\n\\nSo 10 columns of data plus pid to join back to pg_stat_activity proper.\\n\\nDavid J.\\n\\nOn Tue, Nov 8, 2022 at 6:56 PM Andres Freund <andres@anarazel.de> wrote:\\nSeparately from that, I'm a bit worried about starting to add accumulative\\ncounters to pg_stat_activity. It's already gotten hard to use interactively\\ndue to the number of columns - and why stop with the columns you suggest? Why\\nnot show e.g. the total number of reads/writes, tuples inserted / deleted,\\netc. as well?\\n\\nI wonder if we shouldn't add a pg_stat_session or such for per-connection\\ncounters that show not the current state, but accumulated per-session state.I would much rather go down this route than make the existing table wider.pg_stat_activity_state_duration (this patch) [the table - for a given backend - would be empty if track_activities is off]pg_stat_activity_bandwidth_usage (if someone feels like implementing the other items you mention)I'm not really buying into the idea of having multiple states sum their times together. I would expect one column per state. Actually two, because I also suggest that not only is the duration recorded, but a counter be incremented each time a given state becomes the currently active state. Seems like having access to a divisor of some form may be useful.So 10 columns of data plus pid to join back to pg_stat_activity proper.David J.\",\n \"msg_date\": \"Tue, 8 Nov 2022 19:25:27 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\\n> Actually two, because I also suggest that not only is the duration recorded,\\n> but a counter be incremented each time a given state becomes the currently\\n> active state. Seems like having access to a divisor of some form may be\\n> useful.\\n\\nWhat for?\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Nov 2022 18:37:27 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 8, 2022 at 7:37 PM Andres Freund <andres@anarazel.de> wrote:\\n\\n> On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\\n> > Actually two, because I also suggest that not only is the duration\\n> recorded,\\n> > but a counter be incremented each time a given state becomes the\\n> currently\\n> > active state. Seems like having access to a divisor of some form may be\\n> > useful.\\n>\\n> What for?\\n>\\n\\nBecause 5 hours of idle-in-transaction time in a single block means\\nsomething different than the same 5 hours accumulated across 300 mini-idles.\\n\\nDavid J.\\n\\nOn Tue, Nov 8, 2022 at 7:37 PM Andres Freund <andres@anarazel.de> wrote:On 2022-11-08 19:25:27 -0700, David G. Johnston wrote:\\n> Actually two, because I also suggest that not only is the duration recorded,\\n> but a counter be incremented each time a given state becomes the currently\\n> active state. Seems like having access to a divisor of some form may be\\n> useful.\\n\\nWhat for?Because 5 hours of idle-in-transaction time in a single block means something different than the same 5 hours accumulated across 300 mini-idles.David J.\",\n \"msg_date\": \"Tue, 8 Nov 2022 19:43:54 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello hackers,\\n\\nI've sketched the first version of a patch to add pg_stat_session.\\nPlease review this early version.\\n\\nRegards,\\nSergey.\",\n \"msg_date\": \"Wed, 1 Feb 2023 21:45:52 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Wed, Feb 1, 2023 at 12:46 PM Sergey Dudoladov\\n<sergey.dudoladov@gmail.com> wrote:\\n>\\n> I've sketched the first version of a patch to add pg_stat_session.\\n> Please review this early version.\\n\\nHi Sergey!\\n\\nI've taken a look into the patch and got some notes.\\n1. It is hard to understand what fastpath backend state is. What do\\nfastpath metrics mean for a user?\\n2. Anyway, the path \\\"if (PGSTAT_IS_FASTPATH(beentry))\\\" seems\\nunreachable to me. I'm a bit surprised that compilers do not produce\\nwarnings about it. Maybe I'm just wrong.\\n3. Tests do not check any incrementation logic. I think we can have\\nsome test that verifies delta for select some_counter from\\npg_stat_session where pid = pg_backend_pid();\\n4. Macroses like PGSTAT_IS_RUNNING do not look like net win in code\\nreadability and PGSTAT prefix have no semantic load.\\n\\n\\nThat's all I've found so far. Thank you!\\n\\nBest regards, Andrey Borodin.\\n\\nPS. We were doing on-air review session [0], I hope Nik will chime-in\\nwith \\\"usability part of a review\\\".\\n\\n[0] https://youtu.be/vTV8XhWf3mo?t=2404\\n\\n\\n\",\n \"msg_date\": \"Thu, 16 Feb 2023 13:37:41 -0800\",\n \"msg_from\": \"Andrey Borodin <amborodin86@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hello hackers,\\n\\nAndrey and Nik, thank you for selecting this patch for review in\\nPostgres Hacking 101: I've modified the patch based both on your email\\nand the video.\\n\\n1. Session statistics is now collected only for client backends. PG\\ninternal processes like wal sender seem to stop sending statistics\\nafter they have entered their respective main loops.\\n2. Fastpath state now counts towards the running state. I think this\\nspecial case does not justify tracking two extra numbers for every\\nclient backend.\\n3. I've added a small test for pg_stat_session similar to other tests\\nin src/test/regress/sql/sysviews.sql\\n4. Here are the pb_bench results requested in the video review:\\n\\nConditions: no assertions, number of transactions = 1000\\nThe query: SELECT generate_series(1, 10000000) OFFSET 10000000;\\nWith pg_stat_session:\\n latency average = 324.480 ms\\n tps = 3.081857 (without initial connection time)\\n\\nWithout pg_stat_session:\\n latency average = 327.370 ms\\n tps = 3.054651 (without initial connection time)\\n\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Wed, 14 Jun 2023 07:50:35 +0200\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi Sergey,\\n\\nI've done a review of this patch. I found the patch idea very useful,\\nthank you for the patch. I've noted something observing this patch:\\n1. Patch can't be applied on the current master. My review is based on\\n application of this patch over ac68323a878\\n2. Being applied over ac68323a878 patch works as expected.\\n3. Field names seems quite long to me (and they should be uniformly\\n named with the same statistics in other views. For example\\n \\\"running\\\" term is called \\\"active\\\" in pg_stat_database)\\n4. Meaningless spaces at the end of line:\\n - backend_status.c:586\\n - monitoring.sgml:5857\\n5. Patch adds\\n\\n usecs_diff = secs * 1000000 + usecs;\\n\\n at backend_status.c:pgstat_report_activity() to optimize\\n calculations. But\\n\\n pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 +\\nusecs);\\n and \\n pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 +\\nusecs);\\n\\n are left in place after that.\\n6. I'm not sure that I can understand the comment\\n /* Keep statistics for pg_stat_database intact */\\n at backend_status.c:600 correctly. Can you please explain it a\\n little?\\n7. Tests seems incomplete. It looks like we can check increments in\\n all fields playing with transactions in tests.\\n\\nAlso, I have a thought about other possible improvements fitting to\\nthis patch.\\n\\nThe view pg_stat_session is really needed in Postgres but I think it\\nshould have much more statistics. I mean all resource statistics\\nrelated to sessions. Every backend has instrumentation that tracks\\nresource consumption. Data of this instrumentation goes to the\\ncumulative statistics system and is used in monitoring extensions\\n(like pg_stat_statements). I think pg_stat_session view is able to add\\none more dimension of monitoring - a dimension of sessions. In my\\nopinion this view should provide resource consumption statistics of\\ncurrent sessions in two cumulative sets of statistics - since backend\\nstart and since transaction start. Such view will be really useful in\\nmonitoring of long running sessions and transactions providing\\nresource consumption information besides timing statistics.\\n\\nregards, Andrei Zubkov\\nPostgres Professional\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Oct 2023 16:12:42 +0300\",\n \"msg_from\": \"Andrei Zubkov <zubkov@moonset.ru>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\n> I've done a review of this patch. I found the patch idea very useful,\\n> thank you for the patch. I've noted something observing this patch:\\n> 1. Patch can't be applied on the current master. My review is based on\\n> application of this patch over ac68323a878\\n\\nOn top of that not sure if I see the patch on the November commitfest\\n[1]. Please make sure it's there so that cfbot will check the patch.\\n\\n[1]: https://commitfest.postgresql.org/45/\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Oct 2023 16:17:51 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi Aleksander,\\n\\nOn Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\\n> On top of that not sure if I see the patch on the November commitfest\\n> [1]. Please make sure it's there so that cfbot will check the patch.\\n\\nYes, this patch is listed on the November commitfest. cfbot says rebase\\nneeded since 2023-08-21.\\n\\nregards, Andrei Zubkov\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Oct 2023 16:36:32 +0300\",\n \"msg_from\": \"Andrei Zubkov <zubkov@moonset.ru>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\n> On Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\\n> > On top of that not sure if I see the patch on the November commitfest\\n> > [1]. Please make sure it's there so that cfbot will check the patch.\\n>\\n> Yes, this patch is listed on the November commitfest. cfbot says rebase\\n> needed since 2023-08-21.\\n\\nYou are right, I missed the corresponding entry [1].\\n\\n[1]: https://commitfest.postgresql.org/45/3405/\\n\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Wed, 25 Oct 2023 16:38:19 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"On Wed, 25 Oct 2023 at 19:06, Andrei Zubkov <zubkov@moonset.ru> wrote:\\n>\\n> Hi Aleksander,\\n>\\n> On Wed, 2023-10-25 at 16:17 +0300, Aleksander Alekseev wrote:\\n> > On top of that not sure if I see the patch on the November commitfest\\n> > [1]. Please make sure it's there so that cfbot will check the patch.\\n>\\n> Yes, this patch is listed on the November commitfest. cfbot says rebase\\n> needed since 2023-08-21.\\n\\nI have changed the status of commitfest entry to \\\"Returned with\\nFeedback\\\" as Andrei Zubkov's comments have not yet been resolved.\\nPlease feel free to post an updated version of the patch and update\\nthe commitfest entry accordingly.\\n\\nRegards,\\nVignesh\\n\\n\\n\",\n \"msg_date\": \"Sun, 14 Jan 2024 16:34:44 +0530\",\n \"msg_from\": \"vignesh C <vignesh21@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi all,\\n\\n@Andrei Zubkov\\nI've modify the patch to address most of your comments.\\n\\n> I have a thought about other possible improvements fitting to this patch.\\n> I think pg_stat_session view is able to add one more dimension of\\nmonitoring - a dimension of sessions\\n\\nI would like to remind here about the initial scope of this patch. The main\\ngoal of it was to ease tracking \\\"idle in transactions\\\" connections, a\\nfeature that would really help in my work. The \\\"pg_stat_session\\\" came into\\nplay only because the \\\"pg_stat_activity\\\" was seen as an unsuitable place\\nfor the relevant counters. With that I still would like to maintaint the\\nfocus on committing the \\\"idle in transactions\\\" part of pg_stat_session\\nfirst.\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Thu, 1 Feb 2024 18:41:55 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi again,\\n\\n> It looks like we can check increments in all fields playing with\\ntransactions in tests.\\n\\nI've added such tests.\\n\\nRegards,\\nSergey\",\n \"msg_date\": \"Thu, 1 Feb 2024 20:50:15 +0100\",\n \"msg_from\": \"Sergey Dudoladov <sergey.dudoladov@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n },\n {\n \"msg_contents\": \"Hi Sergei,\\n\\n> I still would like to maintaint the focus on committing the \\\"idle in\\ntransactions\\\" part of pg_stat_session first.\\n\\nAgreed.\\n\\nI've done a review of version 0004. This version is applied successful\\nover ce571434ae7, installcheck passed. The behavior of pg_stat_session\\nview and corresponding function looks correct. I've didn't found any\\nissues in the code.\\n\\nNotes about the current state of a patch:\\n\\nNaming\\nthe view and function names 'pg_stat_session' seems correct for this\\nparticular scope of a patch. However possible future resource\\nconsumption statistics are valid for all backends (vacuum for example).\\nRight now it is not clear for me if we can get resource statistics from\\nthose backends while those are listed in the pg_stat_activity view but\\nrenaming to something like 'pg_stat_backend' seems reasonable to me.\\n\\nDocs\\n1. session states referenced in monitoring.sgml is not uniform with\\nthose of the pg_stat_activity view.\\nmonitoring.sgml:4635\\nmonitoring.sgml:4644\\n+ Time in milliseconds this backend spent in the\\n<literal>running</literal> or <literal>fastpath</literal> state.\\nI think those states should be referenced uniformly with\\npg_stat_activity.\\n\\n2. Description of the 'pg_stat_get_session()' function might be as\\nfollows:\\n\\n Returns a row, showing statistics about the client backend with the\\n specified process ID, or one row per client backend if\\n <literal>NULL</literal> is specified. The fields returned are the\\n same as those of <structname>pg_stat_session</structname> view.\\n\\nThe main thought here is to get rid of 'each active backend' because\\n'active backend' looks like backend in the 'active' state.\\n\\nTests\\nCall to a non-existing function is depend on non-existence of a\\nfunction, which can't be guaranteed absolutely. How about to do some\\nkind of obvious error here? Couple examples follows:\\n\\nSELECT 0/0;\\n\\n- or -\\n\\nDO $$\\nBEGIN\\nRAISE 'test error';\\nEND;\\n$$ LANGUAGE plpgsql;\\n\\nMy personal choice would be the last one.\\n\\n-- \\nregards, Andrei Zubkov\\nPostgres Professional\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 12 Feb 2024 15:30:58 +0300\",\n \"msg_from\": \"Andrei Zubkov <zubkov@moonset.ru>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Add connection active, idle time to pg_stat_activity\"\n }\n]","isConversational":false}}},{"rowIdx":52983,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi hackers,\n\nDuring the discussion [1] it was discovered that we have two\nprocedures in execTuples.c that do the same thing:\n\n* MakeSingleTupleTableSlot()\n* MakeTupleTableSlot()\n\nIn fact, MakeSingleTupleTableSlot() is simply a wrapper for\nMakeTupleTableSlot().\n\nI propose keeping only one of these procedures to simplify navigating\nthrough the code and debugging, and maybe saving a CPU cycle or two. A\nsearch for MakeTupleTableSlot produced 8 matches across 2 files, while\nMakeSingleTupleTableSlot is used 41 times across 26 files. Thus the\nproposed patch removes MakeTupleTableSlot and keeps\nMakeSingleTupleTableSlot to keep the patch less invasive and simplify\nbackporting of the other patches. Hopefully, this will not complicate\nthe life of the extension developers too much.\n\nThe patch was tested on MacOS against `master` branch b1ce6c28.\n\n[1]: https://www.postgresql.org/message-id/flat/CAJ7c6TP0AowkUgNL6zcAK-s5HYsVHVBRWfu69FRubPpfwZGM9A%40mail.gmail.com\n\n-- \nBest regards,\nAleksander Alekseev","msg_date":"Fri, 22 Oct 2021 16:39:37 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":true,"msg_subject":"Refactoring: join MakeSingleTupleTableSlot() and MakeTupleTableSlot()"},{"msg_contents":"On Fri, Oct 22, 2021 at 04:39:37PM +0300, Aleksander Alekseev wrote:\n> I propose keeping only one of these procedures to simplify navigating\n> through the code and debugging, and maybe saving a CPU cycle or two. A\n> search for MakeTupleTableSlot produced 8 matches across 2 files, while\n> MakeSingleTupleTableSlot is used 41 times across 26 files. Thus the\n> proposed patch removes MakeTupleTableSlot and keeps\n> MakeSingleTupleTableSlot to keep the patch less invasive and simplify\n> backporting of the other patches. Hopefully, this will not complicate\n> the life of the extension developers too much.\n\nTo make the life of extension developers easier, we could as well have\na compatibility macro so as anybody using MakeTupleTableSlot() won't\nbe annoyed by this change. However, looking around, this does not\nlook like a popular API so I'd be fine with your change as proposed.\n\nOther opinions?\n--\nMichael","msg_date":"Sun, 24 Oct 2021 08:33:12 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"},{"msg_contents":"On 2021-Oct-22, Aleksander Alekseev wrote:\n\n> Hi hackers,\n> \n> During the discussion [1] it was discovered that we have two\n> procedures in execTuples.c that do the same thing:\n> \n> * MakeSingleTupleTableSlot()\n> * MakeTupleTableSlot()\n> \n> In fact, MakeSingleTupleTableSlot() is simply a wrapper for\n> MakeTupleTableSlot().\n\nDid you see the arguments at [1]?\n\n[1] https://www.postgresql.org/message-id/1632520.1613195514%40sss.pgh.pa.us\n\n-- \nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\n\n\n","msg_date":"Mon, 25 Oct 2021 18:47:00 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"},{"msg_contents":"Hi Alvaro,\n\n> Did you see the arguments at [1]?\n>\n> [1] https://www.postgresql.org/message-id/1632520.1613195514%40sss.pgh.pa.us\n\nNo, I missed it. Thanks for sharing.\n\n> If you dig in the git history (see f92e8a4b5 in particular) you'll note\n> that the current version of MakeTupleTableSlot originated as code shared\n> between ExecAllocTableSlot and MakeSingleTupleTableSlot.\n> [...]\n> In short: I'm not okay with doing\n> s/MakeTupleTableSlot/MakeSingleTupleTableSlot/g in a patch that doesn't\n> also introduce matching ExecDropSingleTupleTableSlot calls (unless those\n> exist somewhere already; but where?). If we did clean that up, maybe\n> MakeTupleTableSlot could become \"static\". But I'd still be inclined to\n> keep it physically separate, leaving it to the compiler to decide whether\n> to inline it into the callers.\n> [...]\n\nOK, I will need some time to figure out the actual difference between\nthese two functions and to submit an updated version of the patch.\n\n-- \nBest regards,\nAleksander Alekseev\n\n\n","msg_date":"Tue, 26 Oct 2021 14:48:47 +0300","msg_from":"Aleksander Alekseev <aleksander@timescale.com>","msg_from_op":true,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"},{"msg_contents":"On 2021-Oct-26, Aleksander Alekseev wrote:\n\n> > In short: I'm not okay with doing\n> > s/MakeTupleTableSlot/MakeSingleTupleTableSlot/g in a patch that doesn't\n> > also introduce matching ExecDropSingleTupleTableSlot calls (unless those\n> > exist somewhere already; but where?). If we did clean that up, maybe\n> > MakeTupleTableSlot could become \"static\". But I'd still be inclined to\n> > keep it physically separate, leaving it to the compiler to decide whether\n> > to inline it into the callers.\n\nAnother point that could be made is that perhaps\nMakeSingleTupleTableSlot should always construct a slot using virtual\ntuples rather than passing TTSOps as a parameter?\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\"Ellos andaban todos desnudos como su madre los parió, y también las mujeres,\naunque no vi más que una, harto moza, y todos los que yo vi eran todos\nmancebos, que ninguno vi de edad de más de XXX años\" (Cristóbal Colón)\n\n\n","msg_date":"Tue, 26 Oct 2021 08:54:37 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"},{"msg_contents":"On Tue, Oct 26, 2021 at 7:54 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\n> Another point that could be made is that perhaps\n> MakeSingleTupleTableSlot should always construct a slot using virtual\n> tuples rather than passing TTSOps as a parameter?\n\nI haven't really looked at this issue deeply but that seems like it\nmight be a bit confusing. Then \"single\" would end up being an alias\nfor \"virtual\" which I don't suppose is what anyone is expecting.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 26 Oct 2021 11:03:44 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"},{"msg_contents":"On 2021-Oct-26, Robert Haas wrote:\n\n> On Tue, Oct 26, 2021 at 7:54 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\n> > Another point that could be made is that perhaps\n> > MakeSingleTupleTableSlot should always construct a slot using virtual\n> > tuples rather than passing TTSOps as a parameter?\n> \n> I haven't really looked at this issue deeply but that seems like it\n> might be a bit confusing. Then \"single\" would end up being an alias\n> for \"virtual\" which I don't suppose is what anyone is expecting.\n\nYeah -- another point against that idea is that most of the callers are\nindeed not using virtual tuples, so it doesn't really work. I was just\nthinking that if something wants to process transient tuples they may\njust be virtual and not be forced to make them heap tuples, but on\nlooking again, that's not how the abstraction works.\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\"Siempre hay que alimentar a los dioses, aunque la tierra esté seca\" (Orual)\n\n\n","msg_date":"Tue, 26 Oct 2021 13:36:03 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Refactoring: join MakeSingleTupleTableSlot() and\n MakeTupleTableSlot()"}],"string":"[\n {\n \"msg_contents\": \"Hi hackers,\\n\\nDuring the discussion [1] it was discovered that we have two\\nprocedures in execTuples.c that do the same thing:\\n\\n* MakeSingleTupleTableSlot()\\n* MakeTupleTableSlot()\\n\\nIn fact, MakeSingleTupleTableSlot() is simply a wrapper for\\nMakeTupleTableSlot().\\n\\nI propose keeping only one of these procedures to simplify navigating\\nthrough the code and debugging, and maybe saving a CPU cycle or two. A\\nsearch for MakeTupleTableSlot produced 8 matches across 2 files, while\\nMakeSingleTupleTableSlot is used 41 times across 26 files. Thus the\\nproposed patch removes MakeTupleTableSlot and keeps\\nMakeSingleTupleTableSlot to keep the patch less invasive and simplify\\nbackporting of the other patches. Hopefully, this will not complicate\\nthe life of the extension developers too much.\\n\\nThe patch was tested on MacOS against `master` branch b1ce6c28.\\n\\n[1]: https://www.postgresql.org/message-id/flat/CAJ7c6TP0AowkUgNL6zcAK-s5HYsVHVBRWfu69FRubPpfwZGM9A%40mail.gmail.com\\n\\n-- \\nBest regards,\\nAleksander Alekseev\",\n \"msg_date\": \"Fri, 22 Oct 2021 16:39:37 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Refactoring: join MakeSingleTupleTableSlot() and MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 04:39:37PM +0300, Aleksander Alekseev wrote:\\n> I propose keeping only one of these procedures to simplify navigating\\n> through the code and debugging, and maybe saving a CPU cycle or two. A\\n> search for MakeTupleTableSlot produced 8 matches across 2 files, while\\n> MakeSingleTupleTableSlot is used 41 times across 26 files. Thus the\\n> proposed patch removes MakeTupleTableSlot and keeps\\n> MakeSingleTupleTableSlot to keep the patch less invasive and simplify\\n> backporting of the other patches. Hopefully, this will not complicate\\n> the life of the extension developers too much.\\n\\nTo make the life of extension developers easier, we could as well have\\na compatibility macro so as anybody using MakeTupleTableSlot() won't\\nbe annoyed by this change. However, looking around, this does not\\nlook like a popular API so I'd be fine with your change as proposed.\\n\\nOther opinions?\\n--\\nMichael\",\n \"msg_date\": \"Sun, 24 Oct 2021 08:33:12 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-22, Aleksander Alekseev wrote:\\n\\n> Hi hackers,\\n> \\n> During the discussion [1] it was discovered that we have two\\n> procedures in execTuples.c that do the same thing:\\n> \\n> * MakeSingleTupleTableSlot()\\n> * MakeTupleTableSlot()\\n> \\n> In fact, MakeSingleTupleTableSlot() is simply a wrapper for\\n> MakeTupleTableSlot().\\n\\nDid you see the arguments at [1]?\\n\\n[1] https://www.postgresql.org/message-id/1632520.1613195514%40sss.pgh.pa.us\\n\\n-- \\nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 18:47:00 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"Hi Alvaro,\\n\\n> Did you see the arguments at [1]?\\n>\\n> [1] https://www.postgresql.org/message-id/1632520.1613195514%40sss.pgh.pa.us\\n\\nNo, I missed it. Thanks for sharing.\\n\\n> If you dig in the git history (see f92e8a4b5 in particular) you'll note\\n> that the current version of MakeTupleTableSlot originated as code shared\\n> between ExecAllocTableSlot and MakeSingleTupleTableSlot.\\n> [...]\\n> In short: I'm not okay with doing\\n> s/MakeTupleTableSlot/MakeSingleTupleTableSlot/g in a patch that doesn't\\n> also introduce matching ExecDropSingleTupleTableSlot calls (unless those\\n> exist somewhere already; but where?). If we did clean that up, maybe\\n> MakeTupleTableSlot could become \\\"static\\\". But I'd still be inclined to\\n> keep it physically separate, leaving it to the compiler to decide whether\\n> to inline it into the callers.\\n> [...]\\n\\nOK, I will need some time to figure out the actual difference between\\nthese two functions and to submit an updated version of the patch.\\n\\n-- \\nBest regards,\\nAleksander Alekseev\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 14:48:47 +0300\",\n \"msg_from\": \"Aleksander Alekseev <aleksander@timescale.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-26, Aleksander Alekseev wrote:\\n\\n> > In short: I'm not okay with doing\\n> > s/MakeTupleTableSlot/MakeSingleTupleTableSlot/g in a patch that doesn't\\n> > also introduce matching ExecDropSingleTupleTableSlot calls (unless those\\n> > exist somewhere already; but where?). If we did clean that up, maybe\\n> > MakeTupleTableSlot could become \\\"static\\\". But I'd still be inclined to\\n> > keep it physically separate, leaving it to the compiler to decide whether\\n> > to inline it into the callers.\\n\\nAnother point that could be made is that perhaps\\nMakeSingleTupleTableSlot should always construct a slot using virtual\\ntuples rather than passing TTSOps as a parameter?\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\\"Ellos andaban todos desnudos como su madre los parió, y también las mujeres,\\naunque no vi más que una, harto moza, y todos los que yo vi eran todos\\nmancebos, que ninguno vi de edad de más de XXX años\\\" (Cristóbal Colón)\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 08:54:37 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 7:54 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\\n> Another point that could be made is that perhaps\\n> MakeSingleTupleTableSlot should always construct a slot using virtual\\n> tuples rather than passing TTSOps as a parameter?\\n\\nI haven't really looked at this issue deeply but that seems like it\\nmight be a bit confusing. Then \\\"single\\\" would end up being an alias\\nfor \\\"virtual\\\" which I don't suppose is what anyone is expecting.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:03:44 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-26, Robert Haas wrote:\\n\\n> On Tue, Oct 26, 2021 at 7:54 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\\n> > Another point that could be made is that perhaps\\n> > MakeSingleTupleTableSlot should always construct a slot using virtual\\n> > tuples rather than passing TTSOps as a parameter?\\n> \\n> I haven't really looked at this issue deeply but that seems like it\\n> might be a bit confusing. Then \\\"single\\\" would end up being an alias\\n> for \\\"virtual\\\" which I don't suppose is what anyone is expecting.\\n\\nYeah -- another point against that idea is that most of the callers are\\nindeed not using virtual tuples, so it doesn't really work. I was just\\nthinking that if something wants to process transient tuples they may\\njust be virtual and not be forced to make them heap tuples, but on\\nlooking again, that's not how the abstraction works.\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\\"Siempre hay que alimentar a los dioses, aunque la tierra esté seca\\\" (Orual)\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:36:03 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Refactoring: join MakeSingleTupleTableSlot() and\\n MakeTupleTableSlot()\"\n }\n]","isConversational":false}}},{"rowIdx":52984,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hackers,\n\nI noticed recently that permissions checking is done differently for the \nserver certificate key than the client key. Specifically, on the server \nthe key can have 640 perms if it is owned by root.\n\nOn the server side this change was made in 9a83564c and I think the same \nrational applies equally well to the client key. At the time managed \nkeys on the client may not have been common but they are now.\n\nAttached is a patch to make this change.\n\nI was able to this this manually by hacking 001_ssltests.pl like so:\n\n-\tchmod 0640, \"ssl/${key}_tmp.key\"\n+\tchmod 0600, \"ssl/${key}_tmp.key\"\n \t or die \"failed to change permissions on ssl/${key}_tmp.key: $!\";\n-\tsystem_or_bail(\"sudo chown root ssl/${key}_tmp.key\");\n\nBut this is clearly not going to work for general purpose testing. The \nserver keys also not tested for root ownership so perhaps we do not need \nthat here either.\n\nI looked at trying to make this code common between the server and \nclient but due to the differences in error reporting it seemed like more \ntrouble than it was worth.\n\nRegards,\n-- \n-David\ndavid@pgmasters.net","msg_date":"Fri, 22 Oct 2021 11:41:21 -0400","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Allow root ownership of client certificate key"},{"msg_contents":"On 10/22/21 11:41 AM, David Steele wrote:\n> \n> I noticed recently that permissions checking is done differently for the \n> server certificate key than the client key. Specifically, on the server \n> the key can have 640 perms if it is owned by root.\n> \n> On the server side this change was made in 9a83564c and I think the same \n> rational applies equally well to the client key. At the time managed \n> keys on the client may not have been common but they are now.\n> \n> Attached is a patch to make this change.\n> \n> I was able to this this manually by hacking 001_ssltests.pl like so:\n> \n> - chmod 0640, \"ssl/${key}_tmp.key\"\n> + chmod 0600, \"ssl/${key}_tmp.key\"\n> or die \"failed to change permissions on ssl/${key}_tmp.key: $!\";\n> - system_or_bail(\"sudo chown root ssl/${key}_tmp.key\");\n> \n> But this is clearly not going to work for general purpose testing. The \n> server keys also not tested for root ownership so perhaps we do not need \n> that here either.\n> \n> I looked at trying to make this code common between the server and \n> client but due to the differences in error reporting it seemed like more \n> trouble than it was worth.\n\nAdded to next CF: https://commitfest.postgresql.org/35/3379\n\n-- \n-David\ndavid@pgmasters.net\n\n\n","msg_date":"Thu, 28 Oct 2021 09:08:38 -0400","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"Greetings,\n\n* David Steele (david@pgmasters.net) wrote:\n> I noticed recently that permissions checking is done differently for the\n> server certificate key than the client key. Specifically, on the server the\n> key can have 640 perms if it is owned by root.\n\nYeah, that strikes me as odd too, particularly given that many many\ncases of client-side certificates are application servers and not actual\nend users. If we can justify having a looser check on the PG server\nside then it surely makes sense that an app server could also be\njustified in having such a permission setup (and it definitely happens\noften in Kubernetes/OpenShift and such places where secrets are mounted\nfrom somewhere else).\n\n> On the server side this change was made in 9a83564c and I think the same\n> rational applies equally well to the client key. At the time managed keys on\n> the client may not have been common but they are now.\n\nAgreed.\n\n> Attached is a patch to make this change.\n> \n> I was able to this this manually by hacking 001_ssltests.pl like so:\n> \n> -\tchmod 0640, \"ssl/${key}_tmp.key\"\n> +\tchmod 0600, \"ssl/${key}_tmp.key\"\n> \t or die \"failed to change permissions on ssl/${key}_tmp.key: $!\";\n> -\tsystem_or_bail(\"sudo chown root ssl/${key}_tmp.key\");\n> \n> But this is clearly not going to work for general purpose testing. The\n> server keys also not tested for root ownership so perhaps we do not need\n> that here either.\n\nMakes sense to me.\n\n> I looked at trying to make this code common between the server and client\n> but due to the differences in error reporting it seemed like more trouble\n> than it was worth.\n\nMaybe we should at least have the comments refer to each other though,\nto hopefully encourage future hackers in this area to maintain\nconsistency between the two and avoid what happened before..?\n\n> diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c\n> index 3a7cc8f774..285e772170 100644\n> --- a/src/interfaces/libpq/fe-secure-openssl.c\n> +++ b/src/interfaces/libpq/fe-secure-openssl.c\n> @@ -1234,11 +1234,38 @@ initialize_SSL(PGconn *conn)\n> \t\t\t\t\t\t\t fnbuf);\n> \t\t\treturn -1;\n> \t\t}\n> +\n> +\t\t/*\n> +\t\t* Refuse to load key files owned by users other than us or root.\n> +\t\t*\n> +\t\t* XXX surely we can check this on Windows somehow, too.\n> +\t\t*/\n\nNot really sure if there's actually much point in having this marked in\nthis way as it's not apparently something we're going to actually fix in\nthe near term. Maybe instead something like \"Would be nice to find a\nway to do this on Windows somehow, too, but it isn't clear today how\nto.\"\n\n> +#ifndef WIN32\n> +\t\tif (buf.st_uid != geteuid() && buf.st_uid != 0)\n> +\t\t{\n> +\t\t\tappendPQExpBuffer(&conn->errorMessage,\n> +\t\t\t\t\t\t\t libpq_gettext(\"private key file \\\"%s\\\" must be owned by the current user or root\\n\"),\n> +\t\t\t\t\t\t\t fnbuf);\n> +\t\t\treturn -1;\n> +\t\t}\n> +#endif\n\nBasically the same check as what is done on the server side, so this\nlooks good to me.\n\n> +\t\t/*\n> +\t\t* Require no public access to key file. If the file is owned by us,\n> +\t\t* require mode 0600 or less. If owned by root, require 0640 or less to\n> +\t\t* allow read access through our gid, or a supplementary gid that allows\n> +\t\t* to read system-wide certificates.\n> +\t\t*\n> +\t\t* XXX temporarily suppress check when on Windows, because there may not\n> +\t\t* be proper support for Unix-y file permissions. Need to think of a\n> +\t\t* reasonable check to apply on Windows.\n> +\t\t*/\n\nOn the server-side, we also include a reference to postmaster.c. Not\nsure if we need to do that or not but just figured I'd mention it.\n\n> #ifndef WIN32\n> -\t\tif (!S_ISREG(buf.st_mode) || buf.st_mode & (S_IRWXG | S_IRWXO))\n> +\t\tif ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||\n> +\t\t\t(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))\n> \t\t{\n> \t\t\tappendPQExpBuffer(&conn->errorMessage,\n> -\t\t\t\t\t\t\t libpq_gettext(\"private key file \\\"%s\\\" has group or world access; permissions should be u=rw (0600) or less\\n\"),\n> +\t\t\t\t\t\t\t libpq_gettext(\"private key file \\\"%s\\\" has group or world access; file must have permissions u=rw (0600) or less if owned by the current user, or permissions u=rw,g=r (0640) or less if owned by root.\\n\"),\n> \t\t\t\t\t\t\t fnbuf);\n> \t\t\treturn -1;\n> \t\t}\n\nDo we really want to remove the S_ISREG() check? We have that check\n(although a bit earlier) on the server side and we've had it for a very\nlong time, so I don't think that we want to drop it, certainly not\nwithout some additional discussion as to why we should (and why it would\nmake sense to have that be different between the client side and the\nserver side).\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 14:04:05 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"On 11/8/21 2:04 PM, Stephen Frost wrote:\n> * David Steele (david@pgmasters.net) wrote:\n> \n>> I looked at trying to make this code common between the server and client\n>> but due to the differences in error reporting it seemed like more trouble\n>> than it was worth.\n> \n> Maybe we should at least have the comments refer to each other though,\n> to hopefully encourage future hackers in this area to maintain\n> consistency between the two and avoid what happened before..?\n\nDone.\n\n>> +\n>> +\t\t/*\n>> +\t\t* Refuse to load key files owned by users other than us or root.\n>> +\t\t*\n>> +\t\t* XXX surely we can check this on Windows somehow, too.\n>> +\t\t*/\n> \n> Not really sure if there's actually much point in having this marked in\n> this way as it's not apparently something we're going to actually fix in\n> the near term. Maybe instead something like \"Would be nice to find a\n> way to do this on Windows somehow, too, but it isn't clear today how\n> to.\"\n\nDone.\n\n>> +\t\t/*\n>> +\t\t* Require no public access to key file. If the file is owned by us,\n>> +\t\t* require mode 0600 or less. If owned by root, require 0640 or less to\n>> +\t\t* allow read access through our gid, or a supplementary gid that allows\n>> +\t\t* to read system-wide certificates.\n>> +\t\t*\n>> +\t\t* XXX temporarily suppress check when on Windows, because there may not\n>> +\t\t* be proper support for Unix-y file permissions. Need to think of a\n>> +\t\t* reasonable check to apply on Windows.\n>> +\t\t*/\n> \n> On the server-side, we also include a reference to postmaster.c. Not\n> sure if we need to do that or not but just figured I'd mention it.\n\nLooks like this moved to miscinit.c so probably this comment deserves an \nupdate. That might be better as a separate commit.\n\nIn the patch I referenced the function name instead since that will come \nup in searches when the original function gets renamed/moved.\n\n>> #ifndef WIN32\n>> -\t\tif (!S_ISREG(buf.st_mode) || buf.st_mode & (S_IRWXG | S_IRWXO))\n>> +\t\tif ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||\n>> +\t\t\t(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))\n>> \t\t{\n>> \t\t\tappendPQExpBuffer(&conn->errorMessage,\n>> -\t\t\t\t\t\t\t libpq_gettext(\"private key file \\\"%s\\\" has group or world access; permissions should be u=rw (0600) or less\\n\"),\n>> +\t\t\t\t\t\t\t libpq_gettext(\"private key file \\\"%s\\\" has group or world access; file must have permissions u=rw (0600) or less if owned by the current user, or permissions u=rw,g=r (0640) or less if owned by root.\\n\"),\n>> \t\t\t\t\t\t\t fnbuf);\n>> \t\t\treturn -1;\n>> \t\t}\n> \n> Do we really want to remove the S_ISREG() check? We have that check\n> (although a bit earlier) on the server side and we've had it for a very\n> long time, so I don't think that we want to drop it, certainly not\n> without some additional discussion as to why we should (and why it would\n> make sense to have that be different between the client side and the\n> server side).\n\nOof. Definitely a copy-paste error.\n\nA new version is attached with these changes, plus I consolidated the \nchecks under one comment block to reduce comment and #ifdef duplication.\n\nWe may want to do the same on the server side to make the code blocks \nlook more similar.\n\nAlso, on the server side the S_ISREG() check gets its own error and that \nmight be a good idea on the client side as well. As it is, the error \nmessage on the client is going to be pretty confusing in this case.\n\nRegards,\n-- \n-David\ndavid@pgmasters.net","msg_date":"Mon, 8 Nov 2021 17:36:39 -0500","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"David Steele <david@pgmasters.net> writes:\n> [ client-key-perm-002.patch ]\n\nI took a quick look at this and agree with the proposed behavior\nchange, but also with your self-criticisms:\n\n> We may want to do the same on the server side to make the code blocks \n> look more similar.\n>\n> Also, on the server side the S_ISREG() check gets its own error and that \n> might be a good idea on the client side as well. As it is, the error \n> message on the client is going to be pretty confusing in this case.\n\nParticularly, I think the S_ISREG check should happen before any\nownership/permissions checks; it just seems saner that way.\n\nThe only other nitpick I have is that I'd make the cross-references be\nto the two file names, ie like \"Note that similar checks are performed\nin fe-secure-openssl.c ...\" References to the specific functions seem\nlikely to bit-rot in the face of future code rearrangements.\nI suppose filename references could become obsolete too, but it\nseems less likely.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 18 Jan 2022 15:41:02 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"On 1/18/22 15:41, Tom Lane wrote:\n> David Steele <david@pgmasters.net> writes:\n> \n> I took a quick look at this and agree with the proposed behavior\n> change, but also with your self-criticisms:\n> \n>> We may want to do the same on the server side to make the code blocks\n>> look more similar.\n>>\n>> Also, on the server side the S_ISREG() check gets its own error and that\n>> might be a good idea on the client side as well. As it is, the error\n>> message on the client is going to be pretty confusing in this case.\n> \n> Particularly, I think the S_ISREG check should happen before any\n> ownership/permissions checks; it just seems saner that way.\n\nI was worried about doing too much refactoring in this commit since I \nhave hopes and dreams of it being back-patched. But I'll go ahead and do \nthat and if any part of this can be back-patched we'll consider that \nseparately.\n\n> The only other nitpick I have is that I'd make the cross-references be\n> to the two file names, ie like \"Note that similar checks are performed\n> in fe-secure-openssl.c ...\" References to the specific functions seem\n> likely to bit-rot in the face of future code rearrangements.\n> I suppose filename references could become obsolete too, but it\n> seems less likely.\n\nIt's true that functions are more likely to be renamed, but when I \nrename a function I then search for all the places where it is used so I \ncan update them. If the function name appears in a comment that gets \nupdated as well.\n\nIf you would still prefer filenames I have no strong argument against \nthat, just wanted to explain my logic.\n\nRegards,\n-David\n\n\n","msg_date":"Tue, 18 Jan 2022 16:44:29 -0500","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"David Steele <david@pgmasters.net> writes:\n> On 1/18/22 15:41, Tom Lane wrote:\n>> The only other nitpick I have is that I'd make the cross-references be\n>> to the two file names, ie like \"Note that similar checks are performed\n>> in fe-secure-openssl.c ...\" References to the specific functions seem\n>> likely to bit-rot in the face of future code rearrangements.\n>> I suppose filename references could become obsolete too, but it\n>> seems less likely.\n\n> It's true that functions are more likely to be renamed, but when I \n> rename a function I then search for all the places where it is used so I \n> can update them. If the function name appears in a comment that gets \n> updated as well.\n\nHarsh experience says that a lot of Postgres contributors have zero\ninterest in updating comments two lines away from what they're editing,\nlet alone in some distant branch of the source tree. But I'm not dead\nset on it either way.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 18 Jan 2022 16:51:48 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"Hi Tom,\n\nOn 1/18/22 14:41, Tom Lane wrote:\n> David Steele <david@pgmasters.net> writes:\n>> [ client-key-perm-002.patch ]\n> \n> I took a quick look at this and agree with the proposed behavior\n> change, but also with your self-criticisms:\n> \n>> We may want to do the same on the server side to make the code blocks\n>> look more similar.\n>>\n>> Also, on the server side the S_ISREG() check gets its own error and that\n>> might be a good idea on the client side as well. As it is, the error\n>> message on the client is going to be pretty confusing in this case.\n> \n> Particularly, I think the S_ISREG check should happen before any\n> ownership/permissions checks; it just seems saner that way.\n\nThe two blocks of code now look pretty much identical except for error \nhandling and the reference to the other file. Also, the indentation for \nthe comment on the server side is less but I kept the comment formatting \nthe same to make it easier to copy the comment back and forth.\n\n> The only other nitpick I have is that I'd make the cross-references be\n> to the two file names, ie like \"Note that similar checks are performed\n> in fe-secure-openssl.c ...\" References to the specific functions seem\n> likely to bit-rot in the face of future code rearrangements.\n> I suppose filename references could become obsolete too, but it\n> seems less likely.\n\nUpdated these to reference the file instead of the function.\n\nI still don't think we can commit the test for root ownership, but \ntesting it manually got a whole lot easier after the refactor in \nc3b34a0f. Before that you had to hack up the source tree, which is a \npain depending on how it is mounted (I'm testing in a container).\n\nSo, to test the new functionality, just add this snippet on line 57 of \n001_ssltests.pl:\n\nchmod 0640, \"$cert_tempdir/client.key\"\n\tor die \"failed to change permissions on $cert_tempdir/client.key: $!\";\nsystem_or_bail(\"sudo chown root $cert_tempdir/client.key\");\n\nIf you can think of a way to add this to the tests I'm all ears. Perhaps \nwe could add these lines commented out and explain what they are for?\n\nRegards,\n-David","msg_date":"Wed, 16 Feb 2022 12:57:15 -0600","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"David Steele <david@pgmasters.net> writes:\n> [ client-key-perm-003.patch ]\n\nPushed with a bit of copy-editing of the comments.\n\n> So, to test the new functionality, just add this snippet on line 57 of \n> 001_ssltests.pl:\n> chmod 0640, \"$cert_tempdir/client.key\"\n> \tor die \"failed to change permissions on $cert_tempdir/client.key: $!\";\n> system_or_bail(\"sudo chown root $cert_tempdir/client.key\");\n> If you can think of a way to add this to the tests I'm all ears. Perhaps \n> we could add these lines commented out and explain what they are for?\n\nI believe we have some precedents for invoking this sort of test\noptionally if an appropriate environment variable is set. However,\nI'm having a pretty hard time seeing that there's any real use-case\nfor a test set up like this. The TAP tests are meant for automatic\ntesting, and nobody is going to run automatic tests in an environment\nwhere they'd be allowed to sudo. (Or at least I sure hope nobody\nworking on this project is that naive.)\n\nIf somebody wants to put this in despite that, I'd merely suggest\nthat the server-side logic ought to get exercised too.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 28 Feb 2022 14:20:03 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"On 2/28/22 13:20, Tom Lane wrote:\n> David Steele <david@pgmasters.net> writes:\n>> [ client-key-perm-003.patch ]\n> \n> Pushed with a bit of copy-editing of the comments.\n\nThank you!\n\nAny thoughts on back-patching at least the client portion of this? \nProbably hard to argue that it's a bug, but it is certainly painful.\n\nRegards,\n-David\n\n\n","msg_date":"Mon, 28 Feb 2022 18:07:28 -0600","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"David Steele <david@pgmasters.net> writes:\n> Any thoughts on back-patching at least the client portion of this? \n> Probably hard to argue that it's a bug, but it is certainly painful.\n\nI'd be more eager to do that if we had some field complaints\nabout it. Since we don't, my inclination is not to, but I'm\nonly -0.1 or so; anybody else want to vote?\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 28 Feb 2022 19:12:06 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"Greetings,\n\n* Tom Lane (tgl@sss.pgh.pa.us) wrote:\n> David Steele <david@pgmasters.net> writes:\n> > Any thoughts on back-patching at least the client portion of this? \n> > Probably hard to argue that it's a bug, but it is certainly painful.\n> \n> I'd be more eager to do that if we had some field complaints\n> about it. Since we don't, my inclination is not to, but I'm\n> only -0.1 or so; anybody else want to vote?\n\nThis patch was specifically developed in response to field complaints\nabout it working differently, so there's that. Currently it's being\nworked around in the container environments by copying the key from the\nsecret that's provided to a temporary space where we can modify the\nprivileges, but that's pretty terrible. Would be great to be able to\nget rid of that in favor of being able to use it directly.\n\nThanks,\n\nStephen","msg_date":"Mon, 28 Feb 2022 19:31:53 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"Stephen Frost <sfrost@snowman.net> writes:\n> * Tom Lane (tgl@sss.pgh.pa.us) wrote:\n>> I'd be more eager to do that if we had some field complaints\n>> about it. Since we don't, my inclination is not to, but I'm\n>> only -0.1 or so; anybody else want to vote?\n\n> This patch was specifically developed in response to field complaints\n> about it working differently, so there's that.\n\nHmm ... I didn't recall seeing any on the lists, but a bit of archive\nsearching found\n\nhttps://www.postgresql.org/message-id/flat/20170213184323.6099.18278%40wrigleys.postgresql.org\n\nwherein we'd considered the idea and rejected it, or at least decided\nthat we wanted finer-grained control than the server side needs.\nSo that's *a* field complaint. But are we still worried about the\nconcerns that were raised there?\n\nRe-reading, it looks like the submitter then wanted us to just drop the\nprohibition of group-readability without tying it to root ownership,\nwhich I feel would indeed be pretty dangerous given how many systems have\ngroups like \"users\". But I don't think root-owned-group-readable is such\na problem: if you can create such a file then you can make one owned by\nthe calling user, too.\n\nAnyway, I'd be happier about back-patching if we could document\nactual requests to make it work like the server side does.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 28 Feb 2022 22:15:16 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"On 3/1/22 3:15 AM, Tom Lane wrote:\n> Stephen Frost <sfrost@snowman.net> writes:\n>> * Tom Lane (tgl@sss.pgh.pa.us) wrote:\n>>> I'd be more eager to do that if we had some field complaints\n>>> about it. Since we don't, my inclination is not to, but I'm\n>>> only -0.1 or so; anybody else want to vote?\n> \n>> This patch was specifically developed in response to field complaints\n>> about it working differently, so there's that.\n> \n> Anyway, I'd be happier about back-patching if we could document\n> actual requests to make it work like the server side does.\n> \n\nThis patch is tidy and addresses an incompatibility with Kubernetes, so\n+1 from me for a back-patch.\n\n\nPGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\naround this issue when using certificates for system accounts.\n\nFor example, we use certificates to encrypt and authenticate streaming\nreplication connections. We store certificates in the Kubernetes API as\nSecrets.[1] Kubernetes then hands those certificates/secrets to a\nrunning container by mounting them as files on the filesystem.\n\nThose files and their directories are managed by Kubernetes (as root)\nfrom outside the container, and processes inside the container (as\nnot-root) cannot change them. They are mounted with these permissions:\n\n drwxrwsrwt root postgres /pgconf/tls\n -rw-r----- root postgres /pgconf/tls/ca.crt\n -rw-r----- root postgres /pgconf/tls/tls.crt\n -rw-r----- root postgres /pgconf/tls/tls.key\n\n drwxr-sr-x root postgres /pgconf/tls/replication\n -rw-r----- root postgres /pgconf/tls/replication/ca.crt\n -rw-r----- root postgres /pgconf/tls/replication/tls.crt\n -rw-r----- root postgres /pgconf/tls/replication/tls.key\n\nKubernetes treats the server certificate (top) with the same ownership\nand permissions as the client certificate for the replication user\n(bottom). The server is happy but anything libpq, including walreceiver,\nrejects the latter files for not being \"u=rw (0600) or less\".\n\n\nThere is an open request in the Kubernetes project to provide more\ncontrol over ownership and permissions of mounted secrets.[2] PostgreSQL\nis mentioned repeatedly as motivation for the feature.\n\n\n[1]: https://kubernetes.io/docs/concepts/configuration/secret/\n[2]: https://issue.kubernetes.io/81089\n\n-- Chris\n\n\n","msg_date":"Tue, 1 Mar 2022 23:30:25 -0600","msg_from":"Chris Bandy <bandy.chris@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"Chris Bandy <bandy.chris@gmail.com> writes:\n> On 3/1/22 3:15 AM, Tom Lane wrote:\n>> Anyway, I'd be happier about back-patching if we could document\n>> actual requests to make it work like the server side does.\n\n> PGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\n> around this issue when using certificates for system accounts.\n\nSold then, I'll make it so in a bit.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 02 Mar 2022 09:40:10 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Allow root ownership of client certificate key"},{"msg_contents":"On 3/2/22 08:40, Tom Lane wrote:\n> Chris Bandy <bandy.chris@gmail.com> writes:\n>> On 3/1/22 3:15 AM, Tom Lane wrote:\n>>> Anyway, I'd be happier about back-patching if we could document\n>>> actual requests to make it work like the server side does.\n> \n>> PGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\n>> around this issue when using certificates for system accounts.\n> \n> Sold then, I'll make it so in a bit.\n\nThank you! I think the containers community is really going to \nappreciate this.\n\nRegards,\n-David\n\n\n","msg_date":"Wed, 2 Mar 2022 11:17:34 -0600","msg_from":"David Steele <david@pgmasters.net>","msg_from_op":true,"msg_subject":"Re: Allow root ownership of client certificate key"}],"string":"[\n {\n \"msg_contents\": \"Hackers,\\n\\nI noticed recently that permissions checking is done differently for the \\nserver certificate key than the client key. Specifically, on the server \\nthe key can have 640 perms if it is owned by root.\\n\\nOn the server side this change was made in 9a83564c and I think the same \\nrational applies equally well to the client key. At the time managed \\nkeys on the client may not have been common but they are now.\\n\\nAttached is a patch to make this change.\\n\\nI was able to this this manually by hacking 001_ssltests.pl like so:\\n\\n-\\tchmod 0640, \\\"ssl/${key}_tmp.key\\\"\\n+\\tchmod 0600, \\\"ssl/${key}_tmp.key\\\"\\n \\t or die \\\"failed to change permissions on ssl/${key}_tmp.key: $!\\\";\\n-\\tsystem_or_bail(\\\"sudo chown root ssl/${key}_tmp.key\\\");\\n\\nBut this is clearly not going to work for general purpose testing. The \\nserver keys also not tested for root ownership so perhaps we do not need \\nthat here either.\\n\\nI looked at trying to make this code common between the server and \\nclient but due to the differences in error reporting it seemed like more \\ntrouble than it was worth.\\n\\nRegards,\\n-- \\n-David\\ndavid@pgmasters.net\",\n \"msg_date\": \"Fri, 22 Oct 2021 11:41:21 -0400\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 10/22/21 11:41 AM, David Steele wrote:\\n> \\n> I noticed recently that permissions checking is done differently for the \\n> server certificate key than the client key. Specifically, on the server \\n> the key can have 640 perms if it is owned by root.\\n> \\n> On the server side this change was made in 9a83564c and I think the same \\n> rational applies equally well to the client key. At the time managed \\n> keys on the client may not have been common but they are now.\\n> \\n> Attached is a patch to make this change.\\n> \\n> I was able to this this manually by hacking 001_ssltests.pl like so:\\n> \\n> - chmod 0640, \\\"ssl/${key}_tmp.key\\\"\\n> + chmod 0600, \\\"ssl/${key}_tmp.key\\\"\\n> or die \\\"failed to change permissions on ssl/${key}_tmp.key: $!\\\";\\n> - system_or_bail(\\\"sudo chown root ssl/${key}_tmp.key\\\");\\n> \\n> But this is clearly not going to work for general purpose testing. The \\n> server keys also not tested for root ownership so perhaps we do not need \\n> that here either.\\n> \\n> I looked at trying to make this code common between the server and \\n> client but due to the differences in error reporting it seemed like more \\n> trouble than it was worth.\\n\\nAdded to next CF: https://commitfest.postgresql.org/35/3379\\n\\n-- \\n-David\\ndavid@pgmasters.net\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 09:08:38 -0400\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* David Steele (david@pgmasters.net) wrote:\\n> I noticed recently that permissions checking is done differently for the\\n> server certificate key than the client key. Specifically, on the server the\\n> key can have 640 perms if it is owned by root.\\n\\nYeah, that strikes me as odd too, particularly given that many many\\ncases of client-side certificates are application servers and not actual\\nend users. If we can justify having a looser check on the PG server\\nside then it surely makes sense that an app server could also be\\njustified in having such a permission setup (and it definitely happens\\noften in Kubernetes/OpenShift and such places where secrets are mounted\\nfrom somewhere else).\\n\\n> On the server side this change was made in 9a83564c and I think the same\\n> rational applies equally well to the client key. At the time managed keys on\\n> the client may not have been common but they are now.\\n\\nAgreed.\\n\\n> Attached is a patch to make this change.\\n> \\n> I was able to this this manually by hacking 001_ssltests.pl like so:\\n> \\n> -\\tchmod 0640, \\\"ssl/${key}_tmp.key\\\"\\n> +\\tchmod 0600, \\\"ssl/${key}_tmp.key\\\"\\n> \\t or die \\\"failed to change permissions on ssl/${key}_tmp.key: $!\\\";\\n> -\\tsystem_or_bail(\\\"sudo chown root ssl/${key}_tmp.key\\\");\\n> \\n> But this is clearly not going to work for general purpose testing. The\\n> server keys also not tested for root ownership so perhaps we do not need\\n> that here either.\\n\\nMakes sense to me.\\n\\n> I looked at trying to make this code common between the server and client\\n> but due to the differences in error reporting it seemed like more trouble\\n> than it was worth.\\n\\nMaybe we should at least have the comments refer to each other though,\\nto hopefully encourage future hackers in this area to maintain\\nconsistency between the two and avoid what happened before..?\\n\\n> diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c\\n> index 3a7cc8f774..285e772170 100644\\n> --- a/src/interfaces/libpq/fe-secure-openssl.c\\n> +++ b/src/interfaces/libpq/fe-secure-openssl.c\\n> @@ -1234,11 +1234,38 @@ initialize_SSL(PGconn *conn)\\n> \\t\\t\\t\\t\\t\\t\\t fnbuf);\\n> \\t\\t\\treturn -1;\\n> \\t\\t}\\n> +\\n> +\\t\\t/*\\n> +\\t\\t* Refuse to load key files owned by users other than us or root.\\n> +\\t\\t*\\n> +\\t\\t* XXX surely we can check this on Windows somehow, too.\\n> +\\t\\t*/\\n\\nNot really sure if there's actually much point in having this marked in\\nthis way as it's not apparently something we're going to actually fix in\\nthe near term. Maybe instead something like \\\"Would be nice to find a\\nway to do this on Windows somehow, too, but it isn't clear today how\\nto.\\\"\\n\\n> +#ifndef WIN32\\n> +\\t\\tif (buf.st_uid != geteuid() && buf.st_uid != 0)\\n> +\\t\\t{\\n> +\\t\\t\\tappendPQExpBuffer(&conn->errorMessage,\\n> +\\t\\t\\t\\t\\t\\t\\t libpq_gettext(\\\"private key file \\\\\\\"%s\\\\\\\" must be owned by the current user or root\\\\n\\\"),\\n> +\\t\\t\\t\\t\\t\\t\\t fnbuf);\\n> +\\t\\t\\treturn -1;\\n> +\\t\\t}\\n> +#endif\\n\\nBasically the same check as what is done on the server side, so this\\nlooks good to me.\\n\\n> +\\t\\t/*\\n> +\\t\\t* Require no public access to key file. If the file is owned by us,\\n> +\\t\\t* require mode 0600 or less. If owned by root, require 0640 or less to\\n> +\\t\\t* allow read access through our gid, or a supplementary gid that allows\\n> +\\t\\t* to read system-wide certificates.\\n> +\\t\\t*\\n> +\\t\\t* XXX temporarily suppress check when on Windows, because there may not\\n> +\\t\\t* be proper support for Unix-y file permissions. Need to think of a\\n> +\\t\\t* reasonable check to apply on Windows.\\n> +\\t\\t*/\\n\\nOn the server-side, we also include a reference to postmaster.c. Not\\nsure if we need to do that or not but just figured I'd mention it.\\n\\n> #ifndef WIN32\\n> -\\t\\tif (!S_ISREG(buf.st_mode) || buf.st_mode & (S_IRWXG | S_IRWXO))\\n> +\\t\\tif ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||\\n> +\\t\\t\\t(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))\\n> \\t\\t{\\n> \\t\\t\\tappendPQExpBuffer(&conn->errorMessage,\\n> -\\t\\t\\t\\t\\t\\t\\t libpq_gettext(\\\"private key file \\\\\\\"%s\\\\\\\" has group or world access; permissions should be u=rw (0600) or less\\\\n\\\"),\\n> +\\t\\t\\t\\t\\t\\t\\t libpq_gettext(\\\"private key file \\\\\\\"%s\\\\\\\" has group or world access; file must have permissions u=rw (0600) or less if owned by the current user, or permissions u=rw,g=r (0640) or less if owned by root.\\\\n\\\"),\\n> \\t\\t\\t\\t\\t\\t\\t fnbuf);\\n> \\t\\t\\treturn -1;\\n> \\t\\t}\\n\\nDo we really want to remove the S_ISREG() check? We have that check\\n(although a bit earlier) on the server side and we've had it for a very\\nlong time, so I don't think that we want to drop it, certainly not\\nwithout some additional discussion as to why we should (and why it would\\nmake sense to have that be different between the client side and the\\nserver side).\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 14:04:05 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 11/8/21 2:04 PM, Stephen Frost wrote:\\n> * David Steele (david@pgmasters.net) wrote:\\n> \\n>> I looked at trying to make this code common between the server and client\\n>> but due to the differences in error reporting it seemed like more trouble\\n>> than it was worth.\\n> \\n> Maybe we should at least have the comments refer to each other though,\\n> to hopefully encourage future hackers in this area to maintain\\n> consistency between the two and avoid what happened before..?\\n\\nDone.\\n\\n>> +\\n>> +\\t\\t/*\\n>> +\\t\\t* Refuse to load key files owned by users other than us or root.\\n>> +\\t\\t*\\n>> +\\t\\t* XXX surely we can check this on Windows somehow, too.\\n>> +\\t\\t*/\\n> \\n> Not really sure if there's actually much point in having this marked in\\n> this way as it's not apparently something we're going to actually fix in\\n> the near term. Maybe instead something like \\\"Would be nice to find a\\n> way to do this on Windows somehow, too, but it isn't clear today how\\n> to.\\\"\\n\\nDone.\\n\\n>> +\\t\\t/*\\n>> +\\t\\t* Require no public access to key file. If the file is owned by us,\\n>> +\\t\\t* require mode 0600 or less. If owned by root, require 0640 or less to\\n>> +\\t\\t* allow read access through our gid, or a supplementary gid that allows\\n>> +\\t\\t* to read system-wide certificates.\\n>> +\\t\\t*\\n>> +\\t\\t* XXX temporarily suppress check when on Windows, because there may not\\n>> +\\t\\t* be proper support for Unix-y file permissions. Need to think of a\\n>> +\\t\\t* reasonable check to apply on Windows.\\n>> +\\t\\t*/\\n> \\n> On the server-side, we also include a reference to postmaster.c. Not\\n> sure if we need to do that or not but just figured I'd mention it.\\n\\nLooks like this moved to miscinit.c so probably this comment deserves an \\nupdate. That might be better as a separate commit.\\n\\nIn the patch I referenced the function name instead since that will come \\nup in searches when the original function gets renamed/moved.\\n\\n>> #ifndef WIN32\\n>> -\\t\\tif (!S_ISREG(buf.st_mode) || buf.st_mode & (S_IRWXG | S_IRWXO))\\n>> +\\t\\tif ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||\\n>> +\\t\\t\\t(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))\\n>> \\t\\t{\\n>> \\t\\t\\tappendPQExpBuffer(&conn->errorMessage,\\n>> -\\t\\t\\t\\t\\t\\t\\t libpq_gettext(\\\"private key file \\\\\\\"%s\\\\\\\" has group or world access; permissions should be u=rw (0600) or less\\\\n\\\"),\\n>> +\\t\\t\\t\\t\\t\\t\\t libpq_gettext(\\\"private key file \\\\\\\"%s\\\\\\\" has group or world access; file must have permissions u=rw (0600) or less if owned by the current user, or permissions u=rw,g=r (0640) or less if owned by root.\\\\n\\\"),\\n>> \\t\\t\\t\\t\\t\\t\\t fnbuf);\\n>> \\t\\t\\treturn -1;\\n>> \\t\\t}\\n> \\n> Do we really want to remove the S_ISREG() check? We have that check\\n> (although a bit earlier) on the server side and we've had it for a very\\n> long time, so I don't think that we want to drop it, certainly not\\n> without some additional discussion as to why we should (and why it would\\n> make sense to have that be different between the client side and the\\n> server side).\\n\\nOof. Definitely a copy-paste error.\\n\\nA new version is attached with these changes, plus I consolidated the \\nchecks under one comment block to reduce comment and #ifdef duplication.\\n\\nWe may want to do the same on the server side to make the code blocks \\nlook more similar.\\n\\nAlso, on the server side the S_ISREG() check gets its own error and that \\nmight be a good idea on the client side as well. As it is, the error \\nmessage on the client is going to be pretty confusing in this case.\\n\\nRegards,\\n-- \\n-David\\ndavid@pgmasters.net\",\n \"msg_date\": \"Mon, 8 Nov 2021 17:36:39 -0500\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"David Steele <david@pgmasters.net> writes:\\n> [ client-key-perm-002.patch ]\\n\\nI took a quick look at this and agree with the proposed behavior\\nchange, but also with your self-criticisms:\\n\\n> We may want to do the same on the server side to make the code blocks \\n> look more similar.\\n>\\n> Also, on the server side the S_ISREG() check gets its own error and that \\n> might be a good idea on the client side as well. As it is, the error \\n> message on the client is going to be pretty confusing in this case.\\n\\nParticularly, I think the S_ISREG check should happen before any\\nownership/permissions checks; it just seems saner that way.\\n\\nThe only other nitpick I have is that I'd make the cross-references be\\nto the two file names, ie like \\\"Note that similar checks are performed\\nin fe-secure-openssl.c ...\\\" References to the specific functions seem\\nlikely to bit-rot in the face of future code rearrangements.\\nI suppose filename references could become obsolete too, but it\\nseems less likely.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 18 Jan 2022 15:41:02 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 1/18/22 15:41, Tom Lane wrote:\\n> David Steele <david@pgmasters.net> writes:\\n> \\n> I took a quick look at this and agree with the proposed behavior\\n> change, but also with your self-criticisms:\\n> \\n>> We may want to do the same on the server side to make the code blocks\\n>> look more similar.\\n>>\\n>> Also, on the server side the S_ISREG() check gets its own error and that\\n>> might be a good idea on the client side as well. As it is, the error\\n>> message on the client is going to be pretty confusing in this case.\\n> \\n> Particularly, I think the S_ISREG check should happen before any\\n> ownership/permissions checks; it just seems saner that way.\\n\\nI was worried about doing too much refactoring in this commit since I \\nhave hopes and dreams of it being back-patched. But I'll go ahead and do \\nthat and if any part of this can be back-patched we'll consider that \\nseparately.\\n\\n> The only other nitpick I have is that I'd make the cross-references be\\n> to the two file names, ie like \\\"Note that similar checks are performed\\n> in fe-secure-openssl.c ...\\\" References to the specific functions seem\\n> likely to bit-rot in the face of future code rearrangements.\\n> I suppose filename references could become obsolete too, but it\\n> seems less likely.\\n\\nIt's true that functions are more likely to be renamed, but when I \\nrename a function I then search for all the places where it is used so I \\ncan update them. If the function name appears in a comment that gets \\nupdated as well.\\n\\nIf you would still prefer filenames I have no strong argument against \\nthat, just wanted to explain my logic.\\n\\nRegards,\\n-David\\n\\n\\n\",\n \"msg_date\": \"Tue, 18 Jan 2022 16:44:29 -0500\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"David Steele <david@pgmasters.net> writes:\\n> On 1/18/22 15:41, Tom Lane wrote:\\n>> The only other nitpick I have is that I'd make the cross-references be\\n>> to the two file names, ie like \\\"Note that similar checks are performed\\n>> in fe-secure-openssl.c ...\\\" References to the specific functions seem\\n>> likely to bit-rot in the face of future code rearrangements.\\n>> I suppose filename references could become obsolete too, but it\\n>> seems less likely.\\n\\n> It's true that functions are more likely to be renamed, but when I \\n> rename a function I then search for all the places where it is used so I \\n> can update them. If the function name appears in a comment that gets \\n> updated as well.\\n\\nHarsh experience says that a lot of Postgres contributors have zero\\ninterest in updating comments two lines away from what they're editing,\\nlet alone in some distant branch of the source tree. But I'm not dead\\nset on it either way.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 18 Jan 2022 16:51:48 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"Hi Tom,\\n\\nOn 1/18/22 14:41, Tom Lane wrote:\\n> David Steele <david@pgmasters.net> writes:\\n>> [ client-key-perm-002.patch ]\\n> \\n> I took a quick look at this and agree with the proposed behavior\\n> change, but also with your self-criticisms:\\n> \\n>> We may want to do the same on the server side to make the code blocks\\n>> look more similar.\\n>>\\n>> Also, on the server side the S_ISREG() check gets its own error and that\\n>> might be a good idea on the client side as well. As it is, the error\\n>> message on the client is going to be pretty confusing in this case.\\n> \\n> Particularly, I think the S_ISREG check should happen before any\\n> ownership/permissions checks; it just seems saner that way.\\n\\nThe two blocks of code now look pretty much identical except for error \\nhandling and the reference to the other file. Also, the indentation for \\nthe comment on the server side is less but I kept the comment formatting \\nthe same to make it easier to copy the comment back and forth.\\n\\n> The only other nitpick I have is that I'd make the cross-references be\\n> to the two file names, ie like \\\"Note that similar checks are performed\\n> in fe-secure-openssl.c ...\\\" References to the specific functions seem\\n> likely to bit-rot in the face of future code rearrangements.\\n> I suppose filename references could become obsolete too, but it\\n> seems less likely.\\n\\nUpdated these to reference the file instead of the function.\\n\\nI still don't think we can commit the test for root ownership, but \\ntesting it manually got a whole lot easier after the refactor in \\nc3b34a0f. Before that you had to hack up the source tree, which is a \\npain depending on how it is mounted (I'm testing in a container).\\n\\nSo, to test the new functionality, just add this snippet on line 57 of \\n001_ssltests.pl:\\n\\nchmod 0640, \\\"$cert_tempdir/client.key\\\"\\n\\tor die \\\"failed to change permissions on $cert_tempdir/client.key: $!\\\";\\nsystem_or_bail(\\\"sudo chown root $cert_tempdir/client.key\\\");\\n\\nIf you can think of a way to add this to the tests I'm all ears. Perhaps \\nwe could add these lines commented out and explain what they are for?\\n\\nRegards,\\n-David\",\n \"msg_date\": \"Wed, 16 Feb 2022 12:57:15 -0600\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"David Steele <david@pgmasters.net> writes:\\n> [ client-key-perm-003.patch ]\\n\\nPushed with a bit of copy-editing of the comments.\\n\\n> So, to test the new functionality, just add this snippet on line 57 of \\n> 001_ssltests.pl:\\n> chmod 0640, \\\"$cert_tempdir/client.key\\\"\\n> \\tor die \\\"failed to change permissions on $cert_tempdir/client.key: $!\\\";\\n> system_or_bail(\\\"sudo chown root $cert_tempdir/client.key\\\");\\n> If you can think of a way to add this to the tests I'm all ears. Perhaps \\n> we could add these lines commented out and explain what they are for?\\n\\nI believe we have some precedents for invoking this sort of test\\noptionally if an appropriate environment variable is set. However,\\nI'm having a pretty hard time seeing that there's any real use-case\\nfor a test set up like this. The TAP tests are meant for automatic\\ntesting, and nobody is going to run automatic tests in an environment\\nwhere they'd be allowed to sudo. (Or at least I sure hope nobody\\nworking on this project is that naive.)\\n\\nIf somebody wants to put this in despite that, I'd merely suggest\\nthat the server-side logic ought to get exercised too.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Feb 2022 14:20:03 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 2/28/22 13:20, Tom Lane wrote:\\n> David Steele <david@pgmasters.net> writes:\\n>> [ client-key-perm-003.patch ]\\n> \\n> Pushed with a bit of copy-editing of the comments.\\n\\nThank you!\\n\\nAny thoughts on back-patching at least the client portion of this? \\nProbably hard to argue that it's a bug, but it is certainly painful.\\n\\nRegards,\\n-David\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Feb 2022 18:07:28 -0600\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"David Steele <david@pgmasters.net> writes:\\n> Any thoughts on back-patching at least the client portion of this? \\n> Probably hard to argue that it's a bug, but it is certainly painful.\\n\\nI'd be more eager to do that if we had some field complaints\\nabout it. Since we don't, my inclination is not to, but I'm\\nonly -0.1 or so; anybody else want to vote?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Feb 2022 19:12:06 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Tom Lane (tgl@sss.pgh.pa.us) wrote:\\n> David Steele <david@pgmasters.net> writes:\\n> > Any thoughts on back-patching at least the client portion of this? \\n> > Probably hard to argue that it's a bug, but it is certainly painful.\\n> \\n> I'd be more eager to do that if we had some field complaints\\n> about it. Since we don't, my inclination is not to, but I'm\\n> only -0.1 or so; anybody else want to vote?\\n\\nThis patch was specifically developed in response to field complaints\\nabout it working differently, so there's that. Currently it's being\\nworked around in the container environments by copying the key from the\\nsecret that's provided to a temporary space where we can modify the\\nprivileges, but that's pretty terrible. Would be great to be able to\\nget rid of that in favor of being able to use it directly.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 28 Feb 2022 19:31:53 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"Stephen Frost <sfrost@snowman.net> writes:\\n> * Tom Lane (tgl@sss.pgh.pa.us) wrote:\\n>> I'd be more eager to do that if we had some field complaints\\n>> about it. Since we don't, my inclination is not to, but I'm\\n>> only -0.1 or so; anybody else want to vote?\\n\\n> This patch was specifically developed in response to field complaints\\n> about it working differently, so there's that.\\n\\nHmm ... I didn't recall seeing any on the lists, but a bit of archive\\nsearching found\\n\\nhttps://www.postgresql.org/message-id/flat/20170213184323.6099.18278%40wrigleys.postgresql.org\\n\\nwherein we'd considered the idea and rejected it, or at least decided\\nthat we wanted finer-grained control than the server side needs.\\nSo that's *a* field complaint. But are we still worried about the\\nconcerns that were raised there?\\n\\nRe-reading, it looks like the submitter then wanted us to just drop the\\nprohibition of group-readability without tying it to root ownership,\\nwhich I feel would indeed be pretty dangerous given how many systems have\\ngroups like \\\"users\\\". But I don't think root-owned-group-readable is such\\na problem: if you can create such a file then you can make one owned by\\nthe calling user, too.\\n\\nAnyway, I'd be happier about back-patching if we could document\\nactual requests to make it work like the server side does.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 28 Feb 2022 22:15:16 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 3/1/22 3:15 AM, Tom Lane wrote:\\n> Stephen Frost <sfrost@snowman.net> writes:\\n>> * Tom Lane (tgl@sss.pgh.pa.us) wrote:\\n>>> I'd be more eager to do that if we had some field complaints\\n>>> about it. Since we don't, my inclination is not to, but I'm\\n>>> only -0.1 or so; anybody else want to vote?\\n> \\n>> This patch was specifically developed in response to field complaints\\n>> about it working differently, so there's that.\\n> \\n> Anyway, I'd be happier about back-patching if we could document\\n> actual requests to make it work like the server side does.\\n> \\n\\nThis patch is tidy and addresses an incompatibility with Kubernetes, so\\n+1 from me for a back-patch.\\n\\n\\nPGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\\naround this issue when using certificates for system accounts.\\n\\nFor example, we use certificates to encrypt and authenticate streaming\\nreplication connections. We store certificates in the Kubernetes API as\\nSecrets.[1] Kubernetes then hands those certificates/secrets to a\\nrunning container by mounting them as files on the filesystem.\\n\\nThose files and their directories are managed by Kubernetes (as root)\\nfrom outside the container, and processes inside the container (as\\nnot-root) cannot change them. They are mounted with these permissions:\\n\\n drwxrwsrwt root postgres /pgconf/tls\\n -rw-r----- root postgres /pgconf/tls/ca.crt\\n -rw-r----- root postgres /pgconf/tls/tls.crt\\n -rw-r----- root postgres /pgconf/tls/tls.key\\n\\n drwxr-sr-x root postgres /pgconf/tls/replication\\n -rw-r----- root postgres /pgconf/tls/replication/ca.crt\\n -rw-r----- root postgres /pgconf/tls/replication/tls.crt\\n -rw-r----- root postgres /pgconf/tls/replication/tls.key\\n\\nKubernetes treats the server certificate (top) with the same ownership\\nand permissions as the client certificate for the replication user\\n(bottom). The server is happy but anything libpq, including walreceiver,\\nrejects the latter files for not being \\\"u=rw (0600) or less\\\".\\n\\n\\nThere is an open request in the Kubernetes project to provide more\\ncontrol over ownership and permissions of mounted secrets.[2] PostgreSQL\\nis mentioned repeatedly as motivation for the feature.\\n\\n\\n[1]: https://kubernetes.io/docs/concepts/configuration/secret/\\n[2]: https://issue.kubernetes.io/81089\\n\\n-- Chris\\n\\n\\n\",\n \"msg_date\": \"Tue, 1 Mar 2022 23:30:25 -0600\",\n \"msg_from\": \"Chris Bandy <bandy.chris@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"Chris Bandy <bandy.chris@gmail.com> writes:\\n> On 3/1/22 3:15 AM, Tom Lane wrote:\\n>> Anyway, I'd be happier about back-patching if we could document\\n>> actual requests to make it work like the server side does.\\n\\n> PGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\\n> around this issue when using certificates for system accounts.\\n\\nSold then, I'll make it so in a bit.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 02 Mar 2022 09:40:10 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n },\n {\n \"msg_contents\": \"On 3/2/22 08:40, Tom Lane wrote:\\n> Chris Bandy <bandy.chris@gmail.com> writes:\\n>> On 3/1/22 3:15 AM, Tom Lane wrote:\\n>>> Anyway, I'd be happier about back-patching if we could document\\n>>> actual requests to make it work like the server side does.\\n> \\n>> PGO runs PostgreSQL 10 through 14 in Kubernetes, and we have to work\\n>> around this issue when using certificates for system accounts.\\n> \\n> Sold then, I'll make it so in a bit.\\n\\nThank you! I think the containers community is really going to \\nappreciate this.\\n\\nRegards,\\n-David\\n\\n\\n\",\n \"msg_date\": \"Wed, 2 Mar 2022 11:17:34 -0600\",\n \"msg_from\": \"David Steele <david@pgmasters.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow root ownership of client certificate key\"\n }\n]","isConversational":false}}},{"rowIdx":52985,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hello Tom!\n\nI noticed you are improving pg_dump just now.\n\nSome time ago I experimented with a customer database dump in parallel directory mode -F directory -j (2-4)\n\nI noticed it took quite long to complete.\n\nFurther investigation showed that in this mode with multiple jobs the tables are processed in decreasing size order, which makes sense to avoid a long tail of a big table in one of the jobs prolonging overall dump time.\n\nExactly one table took very long, but seemed to be of moderate size.\n\nBut the size-determination fails to consider the size of toast tables and this table had a big associated toast-table of bytea column(s).\nEven with an analyze at loading time there where no size information of the toast-table in the catalog tables.\n\nI thought of the following alternatives to ameliorate:\n\n1. Using pg_table_size() function in the catalog query\nPos: This reflects the correct size of every relation\nNeg: This goes out to disk and may take a huge impact on databases with very many tables\n\n2. Teaching vacuum to set the toast-table size like it sets it on normal tables\n\n3. Have a command/function for occasionly setting the (approximate) size of toast tables \n\nI think with further work under the way (not yet ready), pg_dump can really profit from parallel/not compressing mode, especially considering the huge amount of bytea/blob/string data in many big customer scenarios.\n\nThoughts?\n\nHans Buschmann\n\n\n","msg_date":"Fri, 22 Oct 2021 16:36:27 +0000","msg_from":"Hans Buschmann <buschmann@nidsa.net>","msg_from_op":true,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Hans Buschmann <buschmann@nidsa.net> writes:\n> Some time ago I experimented with a customer database dump in parallel directory mode -F directory -j (2-4)\n> I noticed it took quite long to complete.\n> Further investigation showed that in this mode with multiple jobs the tables are processed in decreasing size order, which makes sense to avoid a long tail of a big table in one of the jobs prolonging overall dump time.\n> Exactly one table took very long, but seemed to be of moderate size.\n> But the size-determination fails to consider the size of toast tables and this table had a big associated toast-table of bytea column(s).\n\nHmm, yeah, we just use pg_class.relpages for scheduling parallel dumps.\nI'd supposed that would be fine, but maybe it's worth being smarter.\nI think it should be sufficient to add on the toast table's relpages\nvalue; that's maintained by autovacuum on the same terms as relpages\nfor regular tables. See 0005 below.\n\nHere's an update of this patch series:\n\n0001 is the same as before, except I changed collectComments and\ncollectSecLabels to strdup the strings they want and then release\ntheir PGresults. The previous behavior confused valgrind's leak\ntracking, which is only a minor annoyance, but I think we can\njustify changing it now that these functions don't save all of\nthe collected comments or seclabels. In particular, we've got\nno need for the several thousand comments on built-in objects,\nso that that PGresult is at least 100KB bigger than what we're\ngoing to keep.\n\n0002 is updated to account for commit 2acc84c6f.\n\n0003 is the same except I added a missing free().\n\n0004 is a new patch based on an idea from Andres Freund [1]:\nin the functions that repetitively issue the same query against\ndifferent tables, issue just one query and use a WHERE clause\nto restrict the output to the tables we care about. I was\nskeptical about this to start with, but it turns out to be\nquite a spectacular win. On my machine, the time to pg_dump\nthe regression database (with \"-s\") drops from 0.91 seconds\nto 0.39 seconds. For a database with 10000 toy tables, the\ntime drops from 18.1 seconds to 2.3 seconds.\n\n0004 is not committable as-is, because it assumes that the source\nserver has single-array unnest(), which is not true before 8.4.\nWe could fix that by using \"oid = ANY(array-constant)\" conditions\ninstead, but I'm unsure about the performance properties of that\nfor large OID arrays on those old server versions. There's a\ndiscussion at [2] about whether it'd be okay to drop pg_dump's\nsupport for pre-8.4 servers; if we do so, then it would become\nunnecessary to do anything more here.\n\n0005 implements your suggestion of accounting for TOAST data while\nscheduling parallel dumps. I realized while looking at that that\nthere's a pre-existing bug, which this'd exacerbate: on machines\nwith 32-bit off_t, dataLength can overflow. Admittedly such machines\nare just about extinct in the wild, but we do still trouble to support\nthe case. So 0005 also includes code to check for overflow and clamp\nthe result to INT_MAX blocks.\n\nMaybe we should back-patch 0005. OTOH, how likely is it that anyone\nis wrangling tables exceeding 16TB on a machine with 32-bit off_t?\nOr that poor parallel dump scheduling would be a real problem in\nsuch a case?\n\nLastly, 0006 implements the other idea we'd discussed in the other\nthread: for queries that are issued repetitively but not within a\nsingle pg_dump function invocation, use PREPARE/EXECUTE to cut down\nthe overhead. This gets only diminishing returns after 0004, but\nit still brings \"pg_dump -s regression\" down from 0.39s to 0.33s,\nso maybe it's worth doing. I stopped after caching the plans for\nfunctions/aggregates/operators/types, though. The remaining sorts\nof objects aren't likely to appear in typical databases enough times\nto be worth worrying over. (This patch will be a net loss if there\nare more than zero but less than perhaps 10 instances of an object type,\nso there's definitely reasons beyond laziness for not doing more.)\n\n\t\t\tregards, tom lane\n\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\n[2] https://www.postgresql.org/message-id/flat/2923349.1634942313%40sss.pgh.pa.us","msg_date":"Sun, 24 Oct 2021 17:10:55 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"On Sun, Oct 24, 2021 at 05:10:55PM -0400, Tom Lane wrote:\n> 0003 is the same except I added a missing free().\n> \n> 0004 is a new patch based on an idea from Andres Freund [1]:\n> in the functions that repetitively issue the same query against\n> different tables, issue just one query and use a WHERE clause\n> to restrict the output to the tables we care about. I was\n> skeptical about this to start with, but it turns out to be\n> quite a spectacular win. On my machine, the time to pg_dump\n> the regression database (with \"-s\") drops from 0.91 seconds\n> to 0.39 seconds. For a database with 10000 toy tables, the\n> time drops from 18.1 seconds to 2.3 seconds.\n\n+ if (tbloids->len > 1) \n+ appendPQExpBufferChar(tbloids, ','); \n+ appendPQExpBuffer(tbloids, \"%u\", tbinfo->dobj.catId.oid); \n\nI think this should say \n\n+ if (tbloids->len > 0) \n\nThat doesn't matter much since catalogs aren't dumped as such, and we tend to\ncount in base 10 and not base 10000.\n\nBTW, the ACL patch makes the overhead 6x lower (6.9sec vs 1.2sec) for pg_dump -t\nof a single, small table. Thanks for that.\n\n-- \nJustin\n\n\n","msg_date":"Sun, 24 Oct 2021 17:03:37 -0500","msg_from":"Justin Pryzby <pryzby@telsasoft.com>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Justin Pryzby <pryzby@telsasoft.com> writes:\n> On Sun, Oct 24, 2021 at 05:10:55PM -0400, Tom Lane wrote:\n>> + if (tbloids->len > 1)\n\n> I think this should say \n> + if (tbloids->len > 0)\n\nNo, >1 is the correct test, because it's checking the string length\nand we started by stuffing a '{' into the string. Maybe needs a\ncomment.\n\n> BTW, the ACL patch makes the overhead 6x lower (6.9sec vs 1.2sec) for pg_dump -t\n> of a single, small table. Thanks for that.\n\nYeah --- I haven't done any formal measurements of the case where you're\nselecting a small number of tables, but I did note that it decreased a\ngood deal compared to HEAD.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sun, 24 Oct 2021 18:58:41 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"\n________________________________________\n1. Von: Tom Lane <tgl@sss.pgh.pa.us>\n>Maybe we should back-patch 0005. OTOH, how likely is it that anyone\n>is wrangling tables exceeding 16TB on a machine with 32-bit off_t?\n>Or that poor parallel dump scheduling would be a real problem in\n>such a case?\n\nI tested your patch on Windows x64, pg15_devel_25.10.2021 against the customer database\n( 2 core/4 thread NUC,32 GB RAM, 1 NVME-SSD, 4 jobs)\n\npg_dump manually patched with your changes\ndatabase pg14.0, 20 GB shared buffers.\n\nThe dump of the database tables took 3min7sec for a 16 GB database resulting in a directory of 31.1 GB with 1628 files!\n\nThe dump worked like a rush: full cpu-usage, finish.\n\nI don't have the old performance data available, but it is a real improvement, so backpatching may be really woth the effort.\n\nThe former slowing-down table has a ratio from 5169 relpages to 673024 toastpages.\n\nDespite of the great disk usage (about dubbling the size from the db) directory mode seems to be by far the fastest mode especially for databases in the range 1TB+.\n\nFor archiving purposes an extern_to_ postgres tool often fits better for compression and can be applied to the dumped data not withholding the dump process.\n\nI am still working on another big speedup in this scenario (comming soon).\n\n-----------------------------------------------------------\n\n2. Another suggestion considering pg_dump\n\nWith some customer databases I follow a yearly practice of pg_dump/pg_restore to the new major version.\nThis eliminates all bloat and does a full reindex, so the disk data layout is already quite clean.\n\nIt would be very favorable to dump the pages according to the CLUSTER index when defined for a table. This would only concern the select to retrieve the rows and not harm pg_dump's logic.\n\nThis would give perfectly reorganized tables in a pg_dump/pg_restore round.\n\nIf a cluster index is defined by the customer, this expresses the whish to have the table layout in this way and nothing is introduced arbitrarily.\n\nI would suggest to have a flag (--cluster) for pg_dump to activate this new behavior.\n\nI think this is not immediately part of the current patchset, but should be taken into account for pg_dump ameliorations in PG15.\n\nIn the moment I have not yet enough knowledge to propose a patch of this kind ( a logic similar to the cluster command itself). Perhaps someone could jump in ...\n\nThanks for the patch and awaiting your thoughts\n\nHans Buschmann\n\n","msg_date":"Mon, 25 Oct 2021 12:23:59 +0000","msg_from":"Hans Buschmann <buschmann@nidsa.net>","msg_from_op":true,"msg_subject":"AW: Assorted improvements in pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-24 17:10:55 -0400, Tom Lane wrote:\n> 0004 is not committable as-is, because it assumes that the source\n> server has single-array unnest(), which is not true before 8.4.\n> We could fix that by using \"oid = ANY(array-constant)\" conditions\n> instead, but I'm unsure about the performance properties of that\n> for large OID arrays on those old server versions.\n\nIt doesn't seem bad at all. 8.3 assert:\n\nCREATE TABLE foo(oid oid primary key);\nINSERT INTO foo SELECT generate_series(1, 1000000);\npostgres[1164129][1]=# explain ANALYZE SELECT count(*) FROM foo WHERE oid = ANY(ARRAY(SELECT generate_series(1100000, 1, -1)));\n┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐\n│ QUERY PLAN │\n├─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤\n│ Aggregate (cost=81.54..81.55 rows=1 width=0) (actual time=2433.656..2433.656 rows=1 loops=1) │\n│ InitPlan │\n│ -> Result (cost=0.00..0.01 rows=1 width=0) (actual time=0.004..149.425 rows=1100000 loops=1) │\n│ -> Bitmap Heap Scan on foo (cost=42.70..81.50 rows=10 width=0) (actual time=2275.137..2369.478 rows=1000000 loops=1) │\n│ Recheck Cond: (oid = ANY (($0)::oid[])) │\n│ -> Bitmap Index Scan on foo_pkey (cost=0.00..42.69 rows=10 width=0) (actual time=2274.077..2274.077 rows=1000000 loops=1) │\n│ Index Cond: (oid = ANY (($0)::oid[])) │\n│ Total runtime: 2436.201 ms │\n└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘\n(8 rows)\n\nTime: 2437.568 ms (00:02.438)\n\n\n> Lastly, 0006 implements the other idea we'd discussed in the other\n> thread: for queries that are issued repetitively but not within a\n> single pg_dump function invocation, use PREPARE/EXECUTE to cut down\n> the overhead. This gets only diminishing returns after 0004, but\n> it still brings \"pg_dump -s regression\" down from 0.39s to 0.33s,\n> so maybe it's worth doing.\n\nI think it's worth doing. There's things that the batch approach won't help\nwith and even if it doesn't help a lot with the regression test database, I'd\nexpect it to help plenty with other cases.\n\nA test database I had around with lots of functions got drastically faster to\ndump (7.4s to 2.5s), even though the number of queries didn't change\nsignificantly. According to pg_stat_statements plan_time for the dumpFunc\nquery went from 2352ms to 0.4ms - interestingly execution time nearly halves\nas well.\n\n\n> I stopped after caching the plans for\n> functions/aggregates/operators/types, though. The remaining sorts\n> of objects aren't likely to appear in typical databases enough times\n> to be worth worrying over. (This patch will be a net loss if there\n> are more than zero but less than perhaps 10 instances of an object type,\n> so there's definitely reasons beyond laziness for not doing more.)\n\nSeems reasonable.\n\n\n> @@ -7340,25 +7340,37 @@ getDomainConstraints(Archive *fout, TypeInfo *tyinfo)\n> \t\t\t\ti_consrc;\n> \tint\t\t\tntups;\n> \n> -\tquery = createPQExpBuffer();\n> +\tstatic bool query_prepared = false;\n> \n> -\tif (fout->remoteVersion >= 90100)\n> -\t\tappendPQExpBuffer(query, \"SELECT tableoid, oid, conname, \"\n> -\t\t\t\t\t\t \"pg_catalog.pg_get_constraintdef(oid) AS consrc, \"\n> -\t\t\t\t\t\t \"convalidated \"\n> -\t\t\t\t\t\t \"FROM pg_catalog.pg_constraint \"\n> -\t\t\t\t\t\t \"WHERE contypid = '%u'::pg_catalog.oid \"\n> -\t\t\t\t\t\t \"ORDER BY conname\",\n> -\t\t\t\t\t\t tyinfo->dobj.catId.oid);\n> +\tif (!query_prepared)\n> +\t{\n\nI wonder if it'd be better to store this in Archive or such. The approach with\nstatic variables might run into problems with parallel pg_dump at some\npoint. These objects aren't dumped in parallel yet, but still...\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 12:30:24 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-24 17:10:55 -0400, Tom Lane wrote:\n>> +\tstatic bool query_prepared = false;\n\n> I wonder if it'd be better to store this in Archive or such. The approach with\n> static variables might run into problems with parallel pg_dump at some\n> point. These objects aren't dumped in parallel yet, but still...\n\nYeah, I wasn't too happy with the static bools either. However, each\nfunction would need its own field in the struct, which seems like a\nmaintenance annoyance, plus a big hazard for future copy-and-paste\nchanges (ie, copy and paste the wrong flag name -> trouble). Also\nthe Archive struct is shared between dump and restore cases, so\nadding a dozen fields that are irrelevant for restore didn't feel\nright. So I'd like a better idea, but I'm not sure that that one\nis better.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 16:02:34 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"On 2021-Oct-25, Tom Lane wrote:\n\n> Yeah, I wasn't too happy with the static bools either. However, each\n> function would need its own field in the struct, which seems like a\n> maintenance annoyance, plus a big hazard for future copy-and-paste\n> changes (ie, copy and paste the wrong flag name -> trouble). Also\n> the Archive struct is shared between dump and restore cases, so\n> adding a dozen fields that are irrelevant for restore didn't feel\n> right. So I'd like a better idea, but I'm not sure that that one\n> is better.\n\nWhat about a separate struct passed from pg_dump's main() to the\nfunctions that execute queries, containing a bunch of bools? This'd\nstill have the problem that mindless copy and paste would cause a bug,\nbut I wonder if that isn't overstated: if you use the wrong flag,\npg_dump would fail as soon as you try to invoke your query when it\nhasn't been prepared yet.\n\n-- \nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\n\"I'm impressed how quickly you are fixing this obscure issue. I came from \nMS SQL and it would be hard for me to put into words how much of a better job\nyou all are doing on [PostgreSQL].\"\n Steve Midgley, http://archives.postgresql.org/pgsql-sql/2008-08/msg00000.php\n\n\n","msg_date":"Mon, 25 Oct 2021 17:42:23 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Hi,\n\nOn 2021-10-25 16:02:34 -0400, Tom Lane wrote:\n> So I'd like a better idea, but I'm not sure that that one is better.\n\nI guess we could move the prepared-statement handling into a query execution\nhelper. That could then use a hashtable or something similar to check if a\ncertain prepared statement already exists. That'd then centrally be extensible\nto deal with multiple connects etc.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 14:35:50 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> I guess we could move the prepared-statement handling into a query execution\n> helper. That could then use a hashtable or something similar to check if a\n> certain prepared statement already exists. That'd then centrally be extensible\n> to deal with multiple connects etc.\n\nThat seems like more mechanism than is warranted. I tried it with a\nsimple array of booleans, and that seems like not too much of a mess;\nsee revised 0006 attached.\n\n(0001-0005 are the same as before; including them just to satisfy\nthe cfbot.)\n\n\t\t\tregards, tom lane","msg_date":"Tue, 26 Oct 2021 18:31:05 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Here's an updated version of this patch set. The only non-line-number\nchanges are\n\n(1) in 0004, I dealt with the issue of not having unnest() in old branches\nby bumping the minimum remote server version to 8.4. Seeing that we seem\nto have consensus in the other thread to push the minimum up to somewhere\naround 9.2, I see no point in making this patch put in conditional code\nthat we'd shortly rip out again.\n\n(2) I also added some comments to 0004 to hopefully address Justin's\nconfusion about string lengths.\n\nI feel quite fortunate that a month's worth of commitfest hacking\ndidn't break any of these patches. Unless someone intends to\nreview these more thoroughly than they already have, I'd like to\ngo ahead and push them.\n\n\t\t\tregards, tom lane","msg_date":"Fri, 03 Dec 2021 16:33:42 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Assorted improvements in pg_dump"},{"msg_contents":"Hello Tom,\n\nfrom your mail from 25.10.2021:\n\n>0005 implements your suggestion of accounting for TOAST data while\n>scheduling parallel dumps. I realized while looking at that that\n>there's a pre-existing bug, which this'd exacerbate: on machines\n>with 32-bit off_t, dataLength can overflow. Admittedly such machines\n>are just about extinct in the wild, but we do still trouble to support\n>the case. So 0005 also includes code to check for overflow and clamp\n>the result to INT_MAX blocks.\n\n>Maybe we should back-patch 0005. OTOH, how likely is it that anyone\n>is wrangling tables exceeding 16TB on a machine with 32-bit off_t?\n>Or that poor parallel dump scheduling would be a real problem in\n>such a case?\n\nI noticed that you patched master with all the improvements in pg_dump.\n\nDid you change your mind about backpatching patch 0005 to fix the toast size matter?\n\nIt would be rather helpfull for handling existent user data in active branches.\n\n\nOn the matter of 32bit versions I think they are used only in much more little instances.\n\nBTW the 32 bit build of postgres on Windows does not work any more with more modern tool sets (tested with VS2019 and VS2022) albeit not excluded explicitly in the docs. But no one complained yet (for a long time now...).\n\nThanks\n\nHans Buschmann\n\n","msg_date":"Tue, 7 Dec 2021 08:05:32 +0000","msg_from":"Hans Buschmann <buschmann@nidsa.net>","msg_from_op":true,"msg_subject":"AW: Assorted improvements in pg_dump"},{"msg_contents":"Hans Buschmann <buschmann@nidsa.net> writes:\n> I noticed that you patched master with all the improvements in pg_dump.\n> Did you change your mind about backpatching patch 0005 to fix the toast size matter?\n\nI looked briefly at that and found that the patch would have to be\nlargely rewritten, because getTables() looks quite different in the\nolder branches. I'm not really sufficiently excited about the point\nto do that rewriting and re-testing. I think that cases where the\nold logic gets the scheduling badly wrong are probably rare.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 07 Dec 2021 11:18:17 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: AW: Assorted improvements in pg_dump"}],"string":"[\n {\n \"msg_contents\": \"Hello Tom!\\n\\nI noticed you are improving pg_dump just now.\\n\\nSome time ago I experimented with a customer database dump in parallel directory mode -F directory -j (2-4)\\n\\nI noticed it took quite long to complete.\\n\\nFurther investigation showed that in this mode with multiple jobs the tables are processed in decreasing size order, which makes sense to avoid a long tail of a big table in one of the jobs prolonging overall dump time.\\n\\nExactly one table took very long, but seemed to be of moderate size.\\n\\nBut the size-determination fails to consider the size of toast tables and this table had a big associated toast-table of bytea column(s).\\nEven with an analyze at loading time there where no size information of the toast-table in the catalog tables.\\n\\nI thought of the following alternatives to ameliorate:\\n\\n1. Using pg_table_size() function in the catalog query\\nPos: This reflects the correct size of every relation\\nNeg: This goes out to disk and may take a huge impact on databases with very many tables\\n\\n2. Teaching vacuum to set the toast-table size like it sets it on normal tables\\n\\n3. Have a command/function for occasionly setting the (approximate) size of toast tables \\n\\nI think with further work under the way (not yet ready), pg_dump can really profit from parallel/not compressing mode, especially considering the huge amount of bytea/blob/string data in many big customer scenarios.\\n\\nThoughts?\\n\\nHans Buschmann\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 16:36:27 +0000\",\n \"msg_from\": \"Hans Buschmann <buschmann@nidsa.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Hans Buschmann <buschmann@nidsa.net> writes:\\n> Some time ago I experimented with a customer database dump in parallel directory mode -F directory -j (2-4)\\n> I noticed it took quite long to complete.\\n> Further investigation showed that in this mode with multiple jobs the tables are processed in decreasing size order, which makes sense to avoid a long tail of a big table in one of the jobs prolonging overall dump time.\\n> Exactly one table took very long, but seemed to be of moderate size.\\n> But the size-determination fails to consider the size of toast tables and this table had a big associated toast-table of bytea column(s).\\n\\nHmm, yeah, we just use pg_class.relpages for scheduling parallel dumps.\\nI'd supposed that would be fine, but maybe it's worth being smarter.\\nI think it should be sufficient to add on the toast table's relpages\\nvalue; that's maintained by autovacuum on the same terms as relpages\\nfor regular tables. See 0005 below.\\n\\nHere's an update of this patch series:\\n\\n0001 is the same as before, except I changed collectComments and\\ncollectSecLabels to strdup the strings they want and then release\\ntheir PGresults. The previous behavior confused valgrind's leak\\ntracking, which is only a minor annoyance, but I think we can\\njustify changing it now that these functions don't save all of\\nthe collected comments or seclabels. In particular, we've got\\nno need for the several thousand comments on built-in objects,\\nso that that PGresult is at least 100KB bigger than what we're\\ngoing to keep.\\n\\n0002 is updated to account for commit 2acc84c6f.\\n\\n0003 is the same except I added a missing free().\\n\\n0004 is a new patch based on an idea from Andres Freund [1]:\\nin the functions that repetitively issue the same query against\\ndifferent tables, issue just one query and use a WHERE clause\\nto restrict the output to the tables we care about. I was\\nskeptical about this to start with, but it turns out to be\\nquite a spectacular win. On my machine, the time to pg_dump\\nthe regression database (with \\\"-s\\\") drops from 0.91 seconds\\nto 0.39 seconds. For a database with 10000 toy tables, the\\ntime drops from 18.1 seconds to 2.3 seconds.\\n\\n0004 is not committable as-is, because it assumes that the source\\nserver has single-array unnest(), which is not true before 8.4.\\nWe could fix that by using \\\"oid = ANY(array-constant)\\\" conditions\\ninstead, but I'm unsure about the performance properties of that\\nfor large OID arrays on those old server versions. There's a\\ndiscussion at [2] about whether it'd be okay to drop pg_dump's\\nsupport for pre-8.4 servers; if we do so, then it would become\\nunnecessary to do anything more here.\\n\\n0005 implements your suggestion of accounting for TOAST data while\\nscheduling parallel dumps. I realized while looking at that that\\nthere's a pre-existing bug, which this'd exacerbate: on machines\\nwith 32-bit off_t, dataLength can overflow. Admittedly such machines\\nare just about extinct in the wild, but we do still trouble to support\\nthe case. So 0005 also includes code to check for overflow and clamp\\nthe result to INT_MAX blocks.\\n\\nMaybe we should back-patch 0005. OTOH, how likely is it that anyone\\nis wrangling tables exceeding 16TB on a machine with 32-bit off_t?\\nOr that poor parallel dump scheduling would be a real problem in\\nsuch a case?\\n\\nLastly, 0006 implements the other idea we'd discussed in the other\\nthread: for queries that are issued repetitively but not within a\\nsingle pg_dump function invocation, use PREPARE/EXECUTE to cut down\\nthe overhead. This gets only diminishing returns after 0004, but\\nit still brings \\\"pg_dump -s regression\\\" down from 0.39s to 0.33s,\\nso maybe it's worth doing. I stopped after caching the plans for\\nfunctions/aggregates/operators/types, though. The remaining sorts\\nof objects aren't likely to appear in typical databases enough times\\nto be worth worrying over. (This patch will be a net loss if there\\nare more than zero but less than perhaps 10 instances of an object type,\\nso there's definitely reasons beyond laziness for not doing more.)\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\\n[2] https://www.postgresql.org/message-id/flat/2923349.1634942313%40sss.pgh.pa.us\",\n \"msg_date\": \"Sun, 24 Oct 2021 17:10:55 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 05:10:55PM -0400, Tom Lane wrote:\\n> 0003 is the same except I added a missing free().\\n> \\n> 0004 is a new patch based on an idea from Andres Freund [1]:\\n> in the functions that repetitively issue the same query against\\n> different tables, issue just one query and use a WHERE clause\\n> to restrict the output to the tables we care about. I was\\n> skeptical about this to start with, but it turns out to be\\n> quite a spectacular win. On my machine, the time to pg_dump\\n> the regression database (with \\\"-s\\\") drops from 0.91 seconds\\n> to 0.39 seconds. For a database with 10000 toy tables, the\\n> time drops from 18.1 seconds to 2.3 seconds.\\n\\n+ if (tbloids->len > 1) \\n+ appendPQExpBufferChar(tbloids, ','); \\n+ appendPQExpBuffer(tbloids, \\\"%u\\\", tbinfo->dobj.catId.oid); \\n\\nI think this should say \\n\\n+ if (tbloids->len > 0) \\n\\nThat doesn't matter much since catalogs aren't dumped as such, and we tend to\\ncount in base 10 and not base 10000.\\n\\nBTW, the ACL patch makes the overhead 6x lower (6.9sec vs 1.2sec) for pg_dump -t\\nof a single, small table. Thanks for that.\\n\\n-- \\nJustin\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 17:03:37 -0500\",\n \"msg_from\": \"Justin Pryzby <pryzby@telsasoft.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Justin Pryzby <pryzby@telsasoft.com> writes:\\n> On Sun, Oct 24, 2021 at 05:10:55PM -0400, Tom Lane wrote:\\n>> + if (tbloids->len > 1)\\n\\n> I think this should say \\n> + if (tbloids->len > 0)\\n\\nNo, >1 is the correct test, because it's checking the string length\\nand we started by stuffing a '{' into the string. Maybe needs a\\ncomment.\\n\\n> BTW, the ACL patch makes the overhead 6x lower (6.9sec vs 1.2sec) for pg_dump -t\\n> of a single, small table. Thanks for that.\\n\\nYeah --- I haven't done any formal measurements of the case where you're\\nselecting a small number of tables, but I did note that it decreased a\\ngood deal compared to HEAD.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 18:58:41 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"\\n________________________________________\\n1. Von: Tom Lane <tgl@sss.pgh.pa.us>\\n>Maybe we should back-patch 0005. OTOH, how likely is it that anyone\\n>is wrangling tables exceeding 16TB on a machine with 32-bit off_t?\\n>Or that poor parallel dump scheduling would be a real problem in\\n>such a case?\\n\\nI tested your patch on Windows x64, pg15_devel_25.10.2021 against the customer database\\n( 2 core/4 thread NUC,32 GB RAM, 1 NVME-SSD, 4 jobs)\\n\\npg_dump manually patched with your changes\\ndatabase pg14.0, 20 GB shared buffers.\\n\\nThe dump of the database tables took 3min7sec for a 16 GB database resulting in a directory of 31.1 GB with 1628 files!\\n\\nThe dump worked like a rush: full cpu-usage, finish.\\n\\nI don't have the old performance data available, but it is a real improvement, so backpatching may be really woth the effort.\\n\\nThe former slowing-down table has a ratio from 5169 relpages to 673024 toastpages.\\n\\nDespite of the great disk usage (about dubbling the size from the db) directory mode seems to be by far the fastest mode especially for databases in the range 1TB+.\\n\\nFor archiving purposes an extern_to_ postgres tool often fits better for compression and can be applied to the dumped data not withholding the dump process.\\n\\nI am still working on another big speedup in this scenario (comming soon).\\n\\n-----------------------------------------------------------\\n\\n2. Another suggestion considering pg_dump\\n\\nWith some customer databases I follow a yearly practice of pg_dump/pg_restore to the new major version.\\nThis eliminates all bloat and does a full reindex, so the disk data layout is already quite clean.\\n\\nIt would be very favorable to dump the pages according to the CLUSTER index when defined for a table. This would only concern the select to retrieve the rows and not harm pg_dump's logic.\\n\\nThis would give perfectly reorganized tables in a pg_dump/pg_restore round.\\n\\nIf a cluster index is defined by the customer, this expresses the whish to have the table layout in this way and nothing is introduced arbitrarily.\\n\\nI would suggest to have a flag (--cluster) for pg_dump to activate this new behavior.\\n\\nI think this is not immediately part of the current patchset, but should be taken into account for pg_dump ameliorations in PG15.\\n\\nIn the moment I have not yet enough knowledge to propose a patch of this kind ( a logic similar to the cluster command itself). Perhaps someone could jump in ...\\n\\nThanks for the patch and awaiting your thoughts\\n\\nHans Buschmann\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:23:59 +0000\",\n \"msg_from\": \"Hans Buschmann <buschmann@nidsa.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"AW: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-24 17:10:55 -0400, Tom Lane wrote:\\n> 0004 is not committable as-is, because it assumes that the source\\n> server has single-array unnest(), which is not true before 8.4.\\n> We could fix that by using \\\"oid = ANY(array-constant)\\\" conditions\\n> instead, but I'm unsure about the performance properties of that\\n> for large OID arrays on those old server versions.\\n\\nIt doesn't seem bad at all. 8.3 assert:\\n\\nCREATE TABLE foo(oid oid primary key);\\nINSERT INTO foo SELECT generate_series(1, 1000000);\\npostgres[1164129][1]=# explain ANALYZE SELECT count(*) FROM foo WHERE oid = ANY(ARRAY(SELECT generate_series(1100000, 1, -1)));\\n┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐\\n│ QUERY PLAN │\\n├─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤\\n│ Aggregate (cost=81.54..81.55 rows=1 width=0) (actual time=2433.656..2433.656 rows=1 loops=1) │\\n│ InitPlan │\\n│ -> Result (cost=0.00..0.01 rows=1 width=0) (actual time=0.004..149.425 rows=1100000 loops=1) │\\n│ -> Bitmap Heap Scan on foo (cost=42.70..81.50 rows=10 width=0) (actual time=2275.137..2369.478 rows=1000000 loops=1) │\\n│ Recheck Cond: (oid = ANY (($0)::oid[])) │\\n│ -> Bitmap Index Scan on foo_pkey (cost=0.00..42.69 rows=10 width=0) (actual time=2274.077..2274.077 rows=1000000 loops=1) │\\n│ Index Cond: (oid = ANY (($0)::oid[])) │\\n│ Total runtime: 2436.201 ms │\\n└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘\\n(8 rows)\\n\\nTime: 2437.568 ms (00:02.438)\\n\\n\\n> Lastly, 0006 implements the other idea we'd discussed in the other\\n> thread: for queries that are issued repetitively but not within a\\n> single pg_dump function invocation, use PREPARE/EXECUTE to cut down\\n> the overhead. This gets only diminishing returns after 0004, but\\n> it still brings \\\"pg_dump -s regression\\\" down from 0.39s to 0.33s,\\n> so maybe it's worth doing.\\n\\nI think it's worth doing. There's things that the batch approach won't help\\nwith and even if it doesn't help a lot with the regression test database, I'd\\nexpect it to help plenty with other cases.\\n\\nA test database I had around with lots of functions got drastically faster to\\ndump (7.4s to 2.5s), even though the number of queries didn't change\\nsignificantly. According to pg_stat_statements plan_time for the dumpFunc\\nquery went from 2352ms to 0.4ms - interestingly execution time nearly halves\\nas well.\\n\\n\\n> I stopped after caching the plans for\\n> functions/aggregates/operators/types, though. The remaining sorts\\n> of objects aren't likely to appear in typical databases enough times\\n> to be worth worrying over. (This patch will be a net loss if there\\n> are more than zero but less than perhaps 10 instances of an object type,\\n> so there's definitely reasons beyond laziness for not doing more.)\\n\\nSeems reasonable.\\n\\n\\n> @@ -7340,25 +7340,37 @@ getDomainConstraints(Archive *fout, TypeInfo *tyinfo)\\n> \\t\\t\\t\\ti_consrc;\\n> \\tint\\t\\t\\tntups;\\n> \\n> -\\tquery = createPQExpBuffer();\\n> +\\tstatic bool query_prepared = false;\\n> \\n> -\\tif (fout->remoteVersion >= 90100)\\n> -\\t\\tappendPQExpBuffer(query, \\\"SELECT tableoid, oid, conname, \\\"\\n> -\\t\\t\\t\\t\\t\\t \\\"pg_catalog.pg_get_constraintdef(oid) AS consrc, \\\"\\n> -\\t\\t\\t\\t\\t\\t \\\"convalidated \\\"\\n> -\\t\\t\\t\\t\\t\\t \\\"FROM pg_catalog.pg_constraint \\\"\\n> -\\t\\t\\t\\t\\t\\t \\\"WHERE contypid = '%u'::pg_catalog.oid \\\"\\n> -\\t\\t\\t\\t\\t\\t \\\"ORDER BY conname\\\",\\n> -\\t\\t\\t\\t\\t\\t tyinfo->dobj.catId.oid);\\n> +\\tif (!query_prepared)\\n> +\\t{\\n\\nI wonder if it'd be better to store this in Archive or such. The approach with\\nstatic variables might run into problems with parallel pg_dump at some\\npoint. These objects aren't dumped in parallel yet, but still...\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:30:24 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-24 17:10:55 -0400, Tom Lane wrote:\\n>> +\\tstatic bool query_prepared = false;\\n\\n> I wonder if it'd be better to store this in Archive or such. The approach with\\n> static variables might run into problems with parallel pg_dump at some\\n> point. These objects aren't dumped in parallel yet, but still...\\n\\nYeah, I wasn't too happy with the static bools either. However, each\\nfunction would need its own field in the struct, which seems like a\\nmaintenance annoyance, plus a big hazard for future copy-and-paste\\nchanges (ie, copy and paste the wrong flag name -> trouble). Also\\nthe Archive struct is shared between dump and restore cases, so\\nadding a dozen fields that are irrelevant for restore didn't feel\\nright. So I'd like a better idea, but I'm not sure that that one\\nis better.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:02:34 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-25, Tom Lane wrote:\\n\\n> Yeah, I wasn't too happy with the static bools either. However, each\\n> function would need its own field in the struct, which seems like a\\n> maintenance annoyance, plus a big hazard for future copy-and-paste\\n> changes (ie, copy and paste the wrong flag name -> trouble). Also\\n> the Archive struct is shared between dump and restore cases, so\\n> adding a dozen fields that are irrelevant for restore didn't feel\\n> right. So I'd like a better idea, but I'm not sure that that one\\n> is better.\\n\\nWhat about a separate struct passed from pg_dump's main() to the\\nfunctions that execute queries, containing a bunch of bools? This'd\\nstill have the problem that mindless copy and paste would cause a bug,\\nbut I wonder if that isn't overstated: if you use the wrong flag,\\npg_dump would fail as soon as you try to invoke your query when it\\nhasn't been prepared yet.\\n\\n-- \\nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\\n\\\"I'm impressed how quickly you are fixing this obscure issue. I came from \\nMS SQL and it would be hard for me to put into words how much of a better job\\nyou all are doing on [PostgreSQL].\\\"\\n Steve Midgley, http://archives.postgresql.org/pgsql-sql/2008-08/msg00000.php\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 17:42:23 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 16:02:34 -0400, Tom Lane wrote:\\n> So I'd like a better idea, but I'm not sure that that one is better.\\n\\nI guess we could move the prepared-statement handling into a query execution\\nhelper. That could then use a hashtable or something similar to check if a\\ncertain prepared statement already exists. That'd then centrally be extensible\\nto deal with multiple connects etc.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:35:50 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> I guess we could move the prepared-statement handling into a query execution\\n> helper. That could then use a hashtable or something similar to check if a\\n> certain prepared statement already exists. That'd then centrally be extensible\\n> to deal with multiple connects etc.\\n\\nThat seems like more mechanism than is warranted. I tried it with a\\nsimple array of booleans, and that seems like not too much of a mess;\\nsee revised 0006 attached.\\n\\n(0001-0005 are the same as before; including them just to satisfy\\nthe cfbot.)\\n\\n\\t\\t\\tregards, tom lane\",\n \"msg_date\": \"Tue, 26 Oct 2021 18:31:05 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Here's an updated version of this patch set. The only non-line-number\\nchanges are\\n\\n(1) in 0004, I dealt with the issue of not having unnest() in old branches\\nby bumping the minimum remote server version to 8.4. Seeing that we seem\\nto have consensus in the other thread to push the minimum up to somewhere\\naround 9.2, I see no point in making this patch put in conditional code\\nthat we'd shortly rip out again.\\n\\n(2) I also added some comments to 0004 to hopefully address Justin's\\nconfusion about string lengths.\\n\\nI feel quite fortunate that a month's worth of commitfest hacking\\ndidn't break any of these patches. Unless someone intends to\\nreview these more thoroughly than they already have, I'd like to\\ngo ahead and push them.\\n\\n\\t\\t\\tregards, tom lane\",\n \"msg_date\": \"Fri, 03 Dec 2021 16:33:42 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Hello Tom,\\n\\nfrom your mail from 25.10.2021:\\n\\n>0005 implements your suggestion of accounting for TOAST data while\\n>scheduling parallel dumps. I realized while looking at that that\\n>there's a pre-existing bug, which this'd exacerbate: on machines\\n>with 32-bit off_t, dataLength can overflow. Admittedly such machines\\n>are just about extinct in the wild, but we do still trouble to support\\n>the case. So 0005 also includes code to check for overflow and clamp\\n>the result to INT_MAX blocks.\\n\\n>Maybe we should back-patch 0005. OTOH, how likely is it that anyone\\n>is wrangling tables exceeding 16TB on a machine with 32-bit off_t?\\n>Or that poor parallel dump scheduling would be a real problem in\\n>such a case?\\n\\nI noticed that you patched master with all the improvements in pg_dump.\\n\\nDid you change your mind about backpatching patch 0005 to fix the toast size matter?\\n\\nIt would be rather helpfull for handling existent user data in active branches.\\n\\n\\nOn the matter of 32bit versions I think they are used only in much more little instances.\\n\\nBTW the 32 bit build of postgres on Windows does not work any more with more modern tool sets (tested with VS2019 and VS2022) albeit not excluded explicitly in the docs. But no one complained yet (for a long time now...).\\n\\nThanks\\n\\nHans Buschmann\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 08:05:32 +0000\",\n \"msg_from\": \"Hans Buschmann <buschmann@nidsa.net>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"AW: Assorted improvements in pg_dump\"\n },\n {\n \"msg_contents\": \"Hans Buschmann <buschmann@nidsa.net> writes:\\n> I noticed that you patched master with all the improvements in pg_dump.\\n> Did you change your mind about backpatching patch 0005 to fix the toast size matter?\\n\\nI looked briefly at that and found that the patch would have to be\\nlargely rewritten, because getTables() looks quite different in the\\nolder branches. I'm not really sufficiently excited about the point\\nto do that rewriting and re-testing. I think that cases where the\\nold logic gets the scheduling badly wrong are probably rare.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 07 Dec 2021 11:18:17 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: AW: Assorted improvements in pg_dump\"\n }\n]","isConversational":false}}},{"rowIdx":52986,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"While doing some desultory testing, I realized that the commit\nI just pushed (92316a458) broke pg_dump against 8.0 servers:\n\n$ pg_dump -p5480 -s regression\npg_dump: error: schema with OID 11 does not exist\n\nThe reason turns out to be something I'd long forgotten about: except\nfor the few \"bootstrap\" catalogs, our system catalogs didn't use to\nhave fixed OIDs. That changed at 7c13781ee, but 8.0 predates that.\nSo when pg_dump reads a catalog on 8.0, it gets some weird number for\n\"tableoid\", and the logic I just put into common.c's findNamespaceByOid\net al fails to find the resulting DumpableObjects.\n\nSo my first thought was just to revert 92316a458 and give up on it as\na bad idea. However ... does anyone actually still care about being\nable to dump from such ancient servers? In addition to this issue,\nI'm thinking of the discussion at [1] about wanting to use unnest()\nin pg_dump, and of what we would need to do instead in pre-8.4 servers\nthat lack that. Maybe it'd be better to move up pg_dump's minimum\nsupported server version to 8.4 or 9.0, and along the way whack a\nfew more lines of its backward-compatibility hacks. If there is\nanyone out there still using an 8.x server, they could use its\nown pg_dump whenever they get around to migration.\n\nAnother idea would be to ignore \"tableoid\" and instead use the OIDs\nwe're expecting, but that's way too ugly for my taste, especially\ngiven the rather thin argument for committing 92316a458 at all.\n\nAnyway, I think the default answer is \"revert 92316a458 and keep the\ncompatibility goalposts where they are\". But I wanted to open up a\ndiscussion to see if anyone likes the other approach better.\n\n\t\t\tregards, tom lane\n\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\n\n\n","msg_date":"Fri, 22 Oct 2021 18:38:33 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"pg_dump versus ancient server versions"},{"msg_contents":"On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n\n> Anyway, I think the default answer is \"revert 92316a458 and keep the\n> compatibility goalposts where they are\". But I wanted to open up a\n> discussion to see if anyone likes the other approach better.\n>\n> [1]\n> https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\n>\n>\nI'd rather drop legacy support than revert. Even if the benefit of\n92316a456 of is limited to refactoring the fact it was committed is enough\nfor me to feel it is a worthwhile improvement. It's still yet another five\nyears before there won't be a supported release that can dump/restore this\n- so 20 years for someone to have upgraded without having to go to the (not\nthat big a) hassle of installing an out-of-support version as a stop-over.\n\nIn short, IMO, the bar for this kind of situation should be 10 releases at\nmost - 5 of which would be in support at the time the patch goes in. We\ndon't have to actively drop support of older stuff but anything older\nshouldn't be preventing new commits.\n\nDavid J.\n\nOn Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:Anyway, I think the default answer is \"revert 92316a458 and keep the\ncompatibility goalposts where they are\". But I wanted to open up a\ndiscussion to see if anyone likes the other approach better.\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.deI'd rather drop legacy support than revert. Even if the benefit of 92316a456 of is limited to refactoring the fact it was committed is enough for me to feel it is a worthwhile improvement. It's still yet another five years before there won't be a supported release that can dump/restore this - so 20 years for someone to have upgraded without having to go to the (not that big a) hassle of installing an out-of-support version as a stop-over.In short, IMO, the bar for this kind of situation should be 10 releases at most - 5 of which would be in support at the time the patch goes in. We don't have to actively drop support of older stuff but anything older shouldn't be preventing new commits.David J.","msg_date":"Fri, 22 Oct 2021 16:00:19 -0700","msg_from":"\"David G. Johnston\" <david.g.johnston@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Fri, Oct 22, 2021 at 6:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> So my first thought was just to revert 92316a458 and give up on it as\n> a bad idea. However ... does anyone actually still care about being\n> able to dump from such ancient servers?\n\nI think I recently heard about an 8.4 server still out there in the\nwild, but AFAICR it's been a long time since I've heard about anything\nolder.\n\nIt seems to me that if you're upgrading by a dozen server versions in\none shot, it's not a totally crazy idea that you might want to do it\nin steps, or use the pg_dump for the version you have and then hack\nthe dump. I kind of wonder if there's really any hope of a pain-free\nupgrade across that many versions anyway. There are things that can\nbite you despite all the work we've put into pg_dump, like having\nobjects that depend on system objects whose definition has changed\nover the years, plus implicit casting differences, operator precedence\nchanges, => getting deprecated, lots of GUC changes, etc. You are\ngoing to be able to upgrade in the end, but it's probably going to\ntake some work. So I'm not really sure that giving up pg_dump\ncompatibility for versions that old is losing as much as it may seem.\n\nAnother thing to think about in that regard: how likely is that\nPostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\noperating system? I suspect the answer is \"not very.\" I seem to recall\nGreg Stark trying to compile really old versions of PostgreSQL for a\nconference talk some years ago, and he got back to a point where it\njust became impossible to make work on modern toolchains even with a\ndecent amount of hackery. One tends to think of C as about as static a\nthing as can be, but that's kind of missing the point. On my laptop\nfor example, my usual configure invocation fails on 7.4 with:\n\nchecking for SSL_library_init in -lssl... no\nconfigure: error: library 'ssl' is required for OpenSSL\n\nIn fact, I get that same failure on every branch older than 9.2. I\nexpect I could work around that by disabling SSL or finding an older\nversion of OpenSSL that works the way those branches expect, but that\nmight not be the only problem, either. Now I understand you could\nhave PostgreSQL 15 on a new box and PostgreSQL 7.x on an ancient one\nand connect via the network, and it would in all fairness be cool if\nthat Just Worked. But I suspect that even if that did happen in the\nlab, reality wouldn't often be so kind.\n\n--\nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 22 Oct 2021 19:26:57 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\"David G. Johnston\" <david.g.johnston@gmail.com> writes:\n> On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Anyway, I think the default answer is \"revert 92316a458 and keep the\n>> compatibility goalposts where they are\". But I wanted to open up a\n>> discussion to see if anyone likes the other approach better.\n\n> ... IMO, the bar for this kind of situation should be 10 releases at\n> most - 5 of which would be in support at the time the patch goes in. We\n> don't have to actively drop support of older stuff but anything older\n> shouldn't be preventing new commits.\n\nYeah. I checked into when it was that we dropped pre-8.0 support\nfrom pg_dump, and the answer is just about five years ago (64f3524e2).\nSo moving the bar forward by five releases isn't at all out of line.\n8.4 would be eight years past EOL by the time v15 comes out.\n\nOne of the arguments for the previous change was that it was getting\nvery hard to build old releases on modern platforms, thus making it\nhard to do any compatibility testing. I believe the same is starting\nto become true of the 8.x releases, though I've not tried personally\nto build any of them in some time. (The executables I'm using for\nthem date from 2014 or earlier, and have not been recompiled in\nsubsequent platform upgrades ...) Anyway it's definitely not free\nto continue to support old source server versions.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 19:30:25 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> Another thing to think about in that regard: how likely is that\n> PostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\n> operating system? I suspect the answer is \"not very.\" I seem to recall\n> Greg Stark trying to compile really old versions of PostgreSQL for a\n> conference talk some years ago, and he got back to a point where it\n> just became impossible to make work on modern toolchains even with a\n> decent amount of hackery.\n\nRight. The toolchains keep moving, even if the official language\ndefinition doesn't. For grins, I just checked out REL8_4_STABLE\non my M1 Mac, and found that it only gets this far:\n\nchecking test program... ok\nchecking whether long int is 64 bits... no\nchecking whether long long int is 64 bits... no\nconfigure: error: Cannot find a working 64-bit integer type.\n\nwhich turns out to be down to a configure-script issue we fixed\nsome years ago, ie using exit() without a prototype:\n\nconftest.c:158:3: error: implicitly declaring library function 'exit' with type\\\n 'void (int) __attribute__((noreturn))' [-Werror,-Wimplicit-function-declaratio\\\nn]\n exit(! does_int64_work());\n ^\n\nI notice that the configure script is also selecting some warning\nswitches that this compiler doesn't much like, plus it doesn't\nbelieve 2.6.x flex is usable. So that's *at least* three things\nthat'd have to be hacked even to get to a successful configure run.\n\nIndividually such issues are (usually) not very painful, but when\nyou have to recreate all of them at once it's a daunting project.\n\nSo if I had to rebuild 8.4 from scratch right now, I would not be\na happy camper. That seems like a good argument for not deeming\nit to be something we still have to support.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 22 Oct 2021 19:48:13 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 2021-Oct-22, Robert Haas wrote:\n\n> In fact, I get that same failure on every branch older than 9.2. I\n> expect I could work around that by disabling SSL or finding an older\n> version of OpenSSL that works the way those branches expect, but that\n> might not be the only problem, either.\n\nI just tried to build 9.1. My config line there doesn't have ssl, but I\ndo get this in the compile stage:\n\ngram.c:69:25: error: conflicting types for ‘base_yylex’\n 69 | #define yylex base_yylex\n | ^~~~~~~~~~\nscan.c:15241:12: note: in expansion of macro ‘yylex’\n15241 | extern int yylex \\\n | ^~~~~\nIn file included from /pgsql/source/REL9_1_STABLE/src/backend/parser/gram.y:60:\n/pgsql/source/REL9_1_STABLE/src/include/parser/gramparse.h:66:12: note: previous declaration of ‘base_yylex’ was here\n 66 | extern int base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp,\n | ^~~~~~~~~~\ngram.c:69:25: error: conflicting types for ‘base_yylex’\n 69 | #define yylex base_yylex\n | ^~~~~~~~~~\nscan.c:15244:21: note: in expansion of macro ‘yylex’\n15244 | #define YY_DECL int yylex \\\n | ^~~~~\nscan.c:15265:1: note: in expansion of macro ‘YY_DECL’\n15265 | YY_DECL\n | ^~~~~~~\nIn file included from /pgsql/source/REL9_1_STABLE/src/backend/parser/gram.y:60:\n/pgsql/source/REL9_1_STABLE/src/include/parser/gramparse.h:66:12: note: previous declaration of ‘base_yylex’ was here\n 66 | extern int base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp,\n | ^~~~~~~~~~\nmake[3]: *** [../../../src/Makefile.global:655: gram.o] Error 1\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\"El Maquinismo fue proscrito so pena de cosquilleo hasta la muerte\"\n(Ijon Tichy en Viajes, Stanislaw Lem)\n\n\n","msg_date":"Fri, 22 Oct 2021 20:51:22 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Fri, Oct 22, 2021 at 7:51 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\n> I just tried to build 9.1. My config line there doesn't have ssl, but I\n> do get this in the compile stage:\n\nHmm.\n\nYou know, one thing we could think about doing is patching some of the\nolder branches to make them compile on modern machines. That would not\nonly be potentially useful for people who are upgrading from ancient\nversions, but also for hackers trying to do research on the origin of\nbugs or performance problems, and also for people who are trying to\nmaintain some kind of backward compatibility or other and want to test\nagainst old versions.\n\nI don't know whether that's really worth the effort and I expect Tom\nwill say that it's not. If he does say that, he may be right. But I\nthink if I were trying to extract my data from an old 7.4 database, I\nthink I'd find it a lot more useful if I could make 9.0 or 9.2 or\nsomething compile and talk to it than if I had to use v15 and hope\nthat held together somehow. It doesn't really make sense to try to\nkeep compatibility of any sort with versions we can no longer test\nagainst.\n\n--\nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Sun, 24 Oct 2021 16:45:20 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> You know, one thing we could think about doing is patching some of the\n> older branches to make them compile on modern machines. That would not\n> only be potentially useful for people who are upgrading from ancient\n> versions, but also for hackers trying to do research on the origin of\n> bugs or performance problems, and also for people who are trying to\n> maintain some kind of backward compatibility or other and want to test\n> against old versions.\n\nYeah. We have done that in the past; I thought more than once,\nbut right now the only case I can find is d13f41d21/105f3ef49.\nThere are some other post-EOL commits in git, but I think the\nothers were mistakes from over-enthusiastic back-patching, while\nthat one was definitely an intentional portability fix for EOL'd\nversions.\n\n> I don't know whether that's really worth the effort and I expect Tom\n> will say that it's not. If he does say ,that, he may be right.\n\nHmm ... I guess the question is how much work we feel like putting\ninto that, and how we'd track whether old branches still work,\nand on what platforms. It could easily turn into a time sink\nthat's not justified by the value. I do see your point that there's\nsome value in it; I'm just not sure about the cost/benefit ratio.\n\nOne thing we could do that would help circumscribe the costs is to say\n\"we are not going to consider issues involving new compiler warnings\nor bugs caused by more-aggressive optimization\". We could mechanize\nthat pretty effectively by changing configure shortly after a branch's\nEOL to select -O0 and no extra warning flags, so that anyone building\nfrom branch tip would get those switch choices.\n\n(I have no idea what this might look like on the Windows side, but\nI'm concerned by the fact that we seem to need fixes every time a\nnew Visual Studio major version comes out.)\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sun, 24 Oct 2021 17:46:17 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 2021-Oct-24, Robert Haas wrote:\n\n> You know, one thing we could think about doing is patching some of the\n> older branches to make them compile on modern machines. That would not\n> only be potentially useful for people who are upgrading from ancient\n> versions, but also for hackers trying to do research on the origin of\n> bugs or performance problems, and also for people who are trying to\n> maintain some kind of backward compatibility or other and want to test\n> against old versions.\n\nI think it is worth *some* effort, at least as far back as we want to\nclaim that we maintain pg_dump and/or psql compatibility, assuming it is\nnot too onerous. For instance, I wouldn't want to clutter buildfarm or\nCI dashboards with testing these branches, unless it is well isolated\nfrom regular ones; we shouldn't commit anything that's too invasive; and\nwe shouldn't make any claims about supportability of these abandoned\nbranches.\n\nAs an example, I did backpatch one such fix to 8.3 (just over a year)\nand 8.2 (four years) after they had closed -- see d13f41d21538 and\n105f3ef492ab.\n\n-- \nÁlvaro Herrera 39°49'30\"S 73°17'W — https://www.EnterpriseDB.com/\n\"Puedes vivir sólo una vez, pero si lo haces bien, una vez es suficiente\"\n\n\n","msg_date":"Sun, 24 Oct 2021 18:52:00 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Fri, 2021-10-22 at 19:26 -0400, Robert Haas wrote:\n> On Fri, Oct 22, 2021 at 6:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> > So my first thought was just to revert 92316a458 and give up on it as\n> > a bad idea. However ... does anyone actually still care about being\n> > able to dump from such ancient servers?\n> \n> I think I recently heard about an 8.4 server still out there in the\n> wild, but AFAICR it's been a long time since I've heard about anything\n> older.\n\nI had a customer with 8.3 in the not too distant past, but that need not\nstop the show. If necessary, they can dump with 8.3 and restire that.\n\nYours,\nLaurenz Albe\n\n\n\n","msg_date":"Mon, 25 Oct 2021 10:29:19 +0200","msg_from":"Laurenz Albe <laurenz.albe@cybertec.at>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/22/21 19:30, Tom Lane wrote:\n> \"David G. Johnston\" <david.g.johnston@gmail.com> writes:\n>> On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>>> Anyway, I think the default answer is \"revert 92316a458 and keep the\n>>> compatibility goalposts where they are\". But I wanted to open up a\n>>> discussion to see if anyone likes the other approach better.\n>> ... IMO, the bar for this kind of situation should be 10 releases at\n>> most - 5 of which would be in support at the time the patch goes in. We\n>> don't have to actively drop support of older stuff but anything older\n>> shouldn't be preventing new commits.\n> Yeah. I checked into when it was that we dropped pre-8.0 support\n> from pg_dump, and the answer is just about five years ago (64f3524e2).\n> So moving the bar forward by five releases isn't at all out of line.\n> 8.4 would be eight years past EOL by the time v15 comes out.\n>\n> One of the arguments for the previous change was that it was getting\n> very hard to build old releases on modern platforms, thus making it\n> hard to do any compatibility testing. I believe the same is starting\n> to become true of the 8.x releases, though I've not tried personally\n> to build any of them in some time. (The executables I'm using for\n> them date from 2014 or earlier, and have not been recompiled in\n> subsequent platform upgrades ...) Anyway it's definitely not free\n> to continue to support old source server versions.\n\n\nBut we don't need to build them on modern platforms, just run them on\nmodern platforms, ISTM.\n\nSome months ago I built binaries all the way back to 7.2 that with a\nlittle help run on modern Fedora and Ubuntu systems. I just upgraded my\nFedora system from 31 to 34 and they still run. See\n<https://gitlab.com/adunstan/pg-old-bin> One of the intended use cases\nwas to test pg_dump against old versions.\n\nI'm not opposed to us cutting off support for very old versions,\nalthough I think we should only do that very occasionally (no more than\nonce every five years, say) unless there's a very good reason. I'm also\nnot opposed to us making small adjustments to allow us to build old\nversions on modern platforms, but if we do that then we should probably\nhave some buildfarm support for it.\n\n\ncheers\n\n\nandrew\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 08:29:24 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Sun, Oct 24, 2021 at 5:46 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Hmm ... I guess the question is how much work we feel like putting\n> into that, and how we'd track whether old branches still work,\n> and on what platforms. It could easily turn into a time sink\n> that's not justified by the value. I do see your point that there's\n> some value in it; I'm just not sure about the cost/benefit ratio.\n\nRight. Well, we could leave it up to people who care to decide how\nmuch work they want to do, perhaps. But I do find it annoying that\npg_dump is supposed to maintain compatibility with server releases\nthat I can't easily build. Fortunately I don't patch pg_dump very\noften, but if I did, it'd be very difficult for me to verify that\nthings work against really old versions. I know that you (Tom) do a\nlot of work of this type though. In my opinion, if you find yourself\nworking on a project of this type and as part of that you do some\nfixes to an older branch to make it compile, maybe you ought to commit\nthose so that the next person doesn't have the same problem. And maybe\nwhen we add support for newer versions of OpenSSL or Windows, we ought\nto consider back-patching those even to unsupported releases if\nsomeone's willing to do the work. If they're not, they're not, but I\nthink we tend to strongly discourage commits to EOL branches, and I\nthink maybe we should stop doing that. Not that people should\nroutinely back-patch bug fixes, but stuff that makes it easier to\nbuild seems fair game.\n\nI don't think we need to worry too much about users getting the wrong\nimpression. People who want to know what is supported are going to\nlook at our web site for that information, and they are going to look\nfor releases. I can't rule out the possibility that someone is going\nto build an updated version of 7.4 or 8.2 with whatever patches we\nmight choose to commit there, but they're unlikely to think that means\nthose are fully supported branches. And if they somehow do think that\ndespite all evidence to the contrary, we can just tell them that they\nare mistaken.\n\n> One thing we could do that would help circumscribe the costs is to say\n> \"we are not going to consider issues involving new compiler warnings\n> or bugs caused by more-aggressive optimization\". We could mechanize\n> that pretty effectively by changing configure shortly after a branch's\n> EOL to select -O0 and no extra warning flags, so that anyone building\n> from branch tip would get those switch choices.\n\nI don't much like the idea of including -O0 because it seems like it\ncould be confusing. People might not realize that that the build\nsettings have been changed. I don't think that's really the problem\nanyway: anybody who hits compiler warnings in older branches could\ndecide to fix them (and as long as it's a committer who will be\nresponsible for their own work, I think that's totally fine) or enable\n-O0 locally. I routinely do that when I hit problems on older\nbranches, and it helps a lot, but the way I see it, that's such an\neasy change that there's little reason to make it in the source code.\nWhat's a lot more annoying is if the compile fails altogether, or you\ncan't even get past the configure step.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 08:55:37 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Oct 25, 2021 at 8:29 AM Andrew Dunstan <andrew@dunslane.net> wrote:\n> But we don't need to build them on modern platforms, just run them on\n> modern platforms, ISTM.\n\nI don't really agree with this.\n\n> Some months ago I built binaries all the way back to 7.2 that with a\n> little help run on modern Fedora and Ubuntu systems. I just upgraded my\n> Fedora system from 31 to 34 and they still run. See\n> <https://gitlab.com/adunstan/pg-old-bin> One of the intended use cases\n> was to test pg_dump against old versions.\n\nThat's cool, but I don't have a Fedora or Ubuntu VM handy, and it does\nseem like if people are working on testing against old versions, they\nmight even want to be able to recompile with debugging statements\nadded or something. So I think actually compiling is a lot better than\nbeing able to get working binaries from someplace, even though the\nlatter is better than nothing.\n\n> I'm not opposed to us cutting off support for very old versions,\n> although I think we should only do that very occasionally (no more than\n> once every five years, say) unless there's a very good reason. I'm also\n> not opposed to us making small adjustments to allow us to build old\n> versions on modern platforms, but if we do that then we should probably\n> have some buildfarm support for it.\n\nYeah, I think having a small number of buildfarm animals testing very\nold versions would be nice. Perhaps we can call them tyrannosaurus,\nbrontosaurus, triceratops, etc. :-)\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 08:59:56 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> Right. Well, we could leave it up to people who care to decide how\n> much work they want to do, perhaps. But I do find it annoying that\n> pg_dump is supposed to maintain compatibility with server releases\n> that I can't easily build. Fortunately I don't patch pg_dump very\n> often, but if I did, it'd be very difficult for me to verify that\n> things work against really old versions. I know that you (Tom) do a\n> lot of work of this type though. In my opinion, if you find yourself\n> working on a project of this type and as part of that you do some\n> fixes to an older branch to make it compile, maybe you ought to commit\n> those so that the next person doesn't have the same problem.\n\nWell, the answer to that so far is that I've never done such fixes.\nI have the last released versions of old branches laying around,\nand that's what I test against. It's been sufficient so far, although\nif I suddenly needed to do (say) SSL-enabled testing, that would be\na problem because I don't think I built with SSL for any of those\nbranches.\n\nBecause of that angle, I concur with your position that it'd really\nbe desirable to be able to build old versions on modern platforms.\nEven if you've got an old executable, it might be misconfigured for\nthe purpose you have in mind.\n\n> And maybe\n> when we add support for newer versions of OpenSSL or Windows, we ought\n> to consider back-patching those even to unsupported releases if\n> someone's willing to do the work. If they're not, they're not, but I\n> think we tend to strongly discourage commits to EOL branches, and I\n> think maybe we should stop doing that. Not that people should\n> routinely back-patch bug fixes, but stuff that makes it easier to\n> build seems fair game.\n\nWhat concerns me here is that we not get into a position where we're\neffectively still maintaining EOL'd versions. Looking at the git\nhistory yesterday reminded me that we had such a situation back in\nthe early 7.x days. I can see that I still occasionally made commits\ninto 7.1 and 7.2 years after the last releases of those branches,\nwhich ended up being a complete waste of effort. There was no policy\nguiding what to back-patch into what branches, partly because we\ndidn't have a defined EOL policy then. So I want to have a policy\n(and a pretty tight one) before I'll go back to doing that.\n\nRoughly speaking, I think the policy should be \"no feature bug fixes,\nnot even security fixes, for EOL'd branches; only fixes that are\nminimally necessary to make it build on newer platforms\". And\nI want to have a sunset provision even for that. Fixing every branch\nforevermore doesn't scale.\n\nThere's also the question of how we get to a working state in the\nfirst place -- as we found upthread, there's a fair-sized amount\nof work to do just to restore buildability right now, for anything\nthat was EOL'd more than a year or two back. I'm not volunteering\nfor that, but somebody would have to to get things off the ground.\n\nAlso, I concur with Andrew's point that we'd really have to have\nbuildfarm support. However, this might not be as bad as it seems.\nIn principle we might just need to add resurrected branches back to\nthe branches_to_build list. Given my view of what the back-patching\npolicy ought to be, a new build in an old branch might only be\nrequired a couple of times a year, which would not be an undue\ninvestment of buildfarm resources. (Hmmm ... but disk space could\nbecome a problem, particularly on older machines with not so much\ndisk. Do we really need to maintain a separate checkout for each\nbranch? It seems like a fresh checkout from the repo would be\nlittle more expensive than the current copy-a-checkout process.)\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 10:23:40 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Oct 25, 2021 at 10:23 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> What concerns me here is that we not get into a position where we're\n> effectively still maintaining EOL'd versions. Looking at the git\n> history yesterday reminded me that we had such a situation back in\n> the early 7.x days. I can see that I still occasionally made commits\n> into 7.1 and 7.2 years after the last releases of those branches,\n> which ended up being a complete waste of effort. There was no policy\n> guiding what to back-patch into what branches, partly because we\n> didn't have a defined EOL policy then. So I want to have a policy\n> (and a pretty tight one) before I'll go back to doing that.\n>\n> Roughly speaking, I think the policy should be \"no feature bug fixes,\n> not even security fixes, for EOL'd branches; only fixes that are\n> minimally necessary to make it build on newer platforms\". And\n> I want to have a sunset provision even for that. Fixing every branch\n> forevermore doesn't scale.\n\nSure, but you can ameliorate that a lot by just saying it's something\npeople have the *option* to do, not something anybody is *expected* to\ndo. I agree it's best if we continue to discourage back-patching bug\nfixes into supported branches, but I also think we don't need to be\ntoo stringent about this. What I think we don't want is, for example,\nsomebody working at company X deciding to back-patch all the bug fixes\nthat customers of company X cares about into our back-branches, but\nnot the other ones. But on the other hand if somebody is trying to\nbenchmark or test compatibility an old branch and it keeps crashing\nbecause of some bug, telling them that they're not allowed to fix that\nbug because it's not a sufficiently-minimal change to a dead branch is\nkind of ridiculous. In other words, if you try to police every change\nanyone wants to make, e.g. \"well I know that would help YOU build on a\nnewer platform but it doesn't seem like it meets the criteria of the\nminimum necessary change to make it build on a newer platform,\" then\nyou might as well just give up now. Nobody cares about the older\nbranches enough to put work into fixing whatever's wrong and then\nhaving to argue about whether that work ought to be thrown away\nanyway.\n\n> There's also the question of how we get to a working state in the\n> first place -- as we found upthread, there's a fair-sized amount\n> of work to do just to restore buildability right now, for anything\n> that was EOL'd more than a year or two back. I'm not volunteering\n> for that, but somebody would have to to get things off the ground.\n\nRight.\n\n> Also, I concur with Andrew's point that we'd really have to have\n> buildfarm support. However, this might not be as bad as it seems.\n> In principle we might just need to add resurrected branches back to\n> the branches_to_build list. Given my view of what the back-patching\n> policy ought to be, a new build in an old branch might only be\n> required a couple of times a year, which would not be an undue\n> investment of buildfarm resources. (Hmmm ... but disk space could\n> become a problem, particularly on older machines with not so much\n> disk. Do we really need to maintain a separate checkout for each\n> branch? It seems like a fresh checkout from the repo would be\n> little more expensive than the current copy-a-checkout process.)\n\nI suppose it would be useful if we had the ability to do new runs only\nwhen the source code has changed...\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 10:40:29 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> On Mon, Oct 25, 2021 at 10:23 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Roughly speaking, I think the policy should be \"no feature bug fixes,\n>> not even security fixes, for EOL'd branches; only fixes that are\n>> minimally necessary to make it build on newer platforms\". And\n>> I want to have a sunset provision even for that. Fixing every branch\n>> forevermore doesn't scale.\n\n> Sure, but you can ameliorate that a lot by just saying it's something\n> people have the *option* to do, not something anybody is *expected* to\n> do. I agree it's best if we continue to discourage back-patching bug\n> fixes into supported branches, but I also think we don't need to be\n> too stringent about this.\n\nActually, I think we do. If I want to test against 7.4, ISTM I want\nto test against the last released 7.4 version, not something with\narbitrary later changes. Otherwise, what exactly is the point?\n\n>> In principle we might just need to add resurrected branches back to\n>> the branches_to_build list. Given my view of what the back-patching\n>> policy ought to be, a new build in an old branch might only be\n>> required a couple of times a year, which would not be an undue\n>> investment of buildfarm resources.\n\n> I suppose it would be useful if we had the ability to do new runs only\n> when the source code has changed...\n\nUh, don't we have that already? I know you can configure a buildfarm\nanimal to force a run at least every-so-often, but it's not required,\nand I don't think it's even the default.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 11:00:42 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 2021-Oct-25, Tom Lane wrote:\n\n> Roughly speaking, I think the policy should be \"no feature bug fixes,\n> not even security fixes, for EOL'd branches; only fixes that are\n> minimally necessary to make it build on newer platforms\". And\n> I want to have a sunset provision even for that. Fixing every branch\n> forevermore doesn't scale.\n\nAgreed. I think dropping such support at the same time we drop\npsql/pg_dump support is a decent answer to that. That meets the stated\npurpose of being able to test such support, and also it moves forward\naccording to subjective choice per development needs.\n\n> Also, I concur with Andrew's point that we'd really have to have\n> buildfarm support. However, this might not be as bad as it seems.\n> In principle we might just need to add resurrected branches back to\n> the branches_to_build list.\n\nWell, we would add them to *some* list, but not to the one used by stock\nBF members -- not only because of the diskspace issue but also because\nof the time to build. I suggest that we should have a separate\nlist-of-branches file that would only be used by BF members especially\nconfigured to do so; and hopefully we won't allow more than a handful\nanimals to do that but rather a well-chosen subset, and also maybe allow\nonly GCC rather than try to support other compilers. (There's no need\nto ensure compilability on any Windows platform, for example.)\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\"Ed is the standard text editor.\"\n http://groups.google.com/group/alt.religion.emacs/msg/8d94ddab6a9b0ad3\n\n\n","msg_date":"Mon, 25 Oct 2021 12:05:22 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Actually, I think we do. If I want to test against 7.4, ISTM I want\n> to test against the last released 7.4 version, not something with\n> arbitrary later changes. Otherwise, what exactly is the point?\n\n1. You're free to check out any commit you like.\n\n2. Nothing I said can reasonably be confused with \"let's allow\narbitrary later changes.\"\n\n> Uh, don't we have that already? I know you can configure a buildfarm\n> animal to force a run at least every-so-often, but it's not required,\n> and I don't think it's even the default.\n\nOh, OK. I wonder how that plays with the buildfarm status page's\ndesire to drop old results that are more than 30 days old. I guess\nyou'd just need to force a run at least every 28 days or something.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 25 Oct 2021 11:09:04 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 11:09, Robert Haas wrote:\n> On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Actually, I think we do. If I want to test against 7.4, ISTM I want\n>> to test against the last released 7.4 version, not something with\n>> arbitrary later changes. Otherwise, what exactly is the point?\n> 1. You're free to check out any commit you like.\n>\n> 2. Nothing I said can reasonably be confused with \"let's allow\n> arbitrary later changes.\"\n>\n>> Uh, don't we have that already? I know you can configure a buildfarm\n>> animal to force a run at least every-so-often, but it's not required,\n>> and I don't think it's even the default.\n\n\nYes, in fact its rather discouraged. The default is just to build when\nthere's a code change detected.\n\n\n> Oh, OK. I wonder how that plays with the buildfarm status page's\n> desire to drop old results that are more than 30 days old. I guess\n> you'd just need to force a run at least every 28 days or something.\n>\n\nWell, we could do that, or we could modify the way the server does the\nstatus. The table it's based on has the last 500 records for each branch\nfor each animal, so the data is there.\n\n\ncheers\n\n\nandrew\n\n\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 11:25:00 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Actually, I think we do. If I want to test against 7.4, ISTM I want\n>> to test against the last released 7.4 version, not something with\n>> arbitrary later changes. Otherwise, what exactly is the point?\n\n> 1. You're free to check out any commit you like.\n\nYeah, and get something that won't build. If there's any point\nto this work at all, it has to be that we'll maintain the closest\npossible buildable approximation to the last released version.\n\n> Oh, OK. I wonder how that plays with the buildfarm status page's\n> desire to drop old results that are more than 30 days old. I guess\n> you'd just need to force a run at least every 28 days or something.\n\nI don't think it's a problem. If we haven't committed anything to\nbranch X in a month, it's likely not interesting. It might be worth\nhaving a way to get the website to show results further back than\na month, but that doesn't need to be in the default view.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 11:26:26 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 10:23, Tom Lane wrote:\n>\n> Also, I concur with Andrew's point that we'd really have to have\n> buildfarm support. However, this might not be as bad as it seems.\n> In principle we might just need to add resurrected branches back to\n> the branches_to_build list. Given my view of what the back-patching\n> policy ought to be, a new build in an old branch might only be\n> required a couple of times a year, which would not be an undue\n> investment of buildfarm resources. (Hmmm ... but disk space could\n> become a problem, particularly on older machines with not so much\n> disk. Do we really need to maintain a separate checkout for each\n> branch? It seems like a fresh checkout from the repo would be\n> little more expensive than the current copy-a-checkout process.)\n\n\nIf you set it up with these settings then the disk space used is minimal:\n\n git_use_workdirs => 1,\n rm_worktrees => 1,\n\nSo I have this on crake:\n\n andrew@emma:root $ du -sh REL*/pgsql\n 5.5M REL_10_STABLE/pgsql\n 5.6M REL_11_STABLE/pgsql\n 5.6M REL_12_STABLE/pgsql\n 5.6M REL_13_STABLE/pgsql\n 2.0M REL_14_STABLE/pgsql\n 2.6M REL9_5_STABLE/pgsql\n 5.5M REL9_6_STABLE/pgsql\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 11:28:04 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 11:05, Alvaro Herrera wrote:\n>\n>> Also, I concur with Andrew's point that we'd really have to have\n>> buildfarm support. However, this might not be as bad as it seems.\n>> In principle we might just need to add resurrected branches back to\n>> the branches_to_build list.\n> Well, we would add them to *some* list, but not to the one used by stock\n> BF members -- not only because of the diskspace issue but also because\n> of the time to build. I suggest that we should have a separate\n> list-of-branches file that would only be used by BF members especially\n> configured to do so; and hopefully we won't allow more than a handful\n> animals to do that but rather a well-chosen subset, and also maybe allow\n> only GCC rather than try to support other compilers. (There's no need\n> to ensure compilability on any Windows platform, for example.)\n\n\nWell, we do build with gcc on Windows :-) But yes, maybe we should make\nthis a more opt-in process.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 11:30:40 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Alvaro Herrera <alvherre@alvh.no-ip.org> writes:\n> On 2021-Oct-25, Tom Lane wrote:\n>> Also, I concur with Andrew's point that we'd really have to have\n>> buildfarm support. However, this might not be as bad as it seems.\n>> In principle we might just need to add resurrected branches back to\n>> the branches_to_build list.\n\n> Well, we would add them to *some* list, but not to the one used by stock\n> BF members -- not only because of the diskspace issue but also because\n> of the time to build. I suggest that we should have a separate\n> list-of-branches file that would only be used by BF members especially\n> configured to do so; and hopefully we won't allow more than a handful\n> animals to do that but rather a well-chosen subset, and also maybe allow\n> only GCC rather than try to support other compilers. (There's no need\n> to ensure compilability on any Windows platform, for example.)\n\nMeh. I don't think that's a great approach, because then we're only\nensuring buildability on a rather static set of platforms. The whole\npoint here is that when release N+1 of $your_favorite_platform arrives,\nwe want to know whether the old branches still build on it. If the\ndefault behavior for new buildfarm animals is to ignore the old branches,\nwe're much less likely to find that out.\n\nIt's also unclear to me why we'd leave Windows out of this discussion.\nWe keep saying we want to encourage Windows-based hackers to contribute,\nso doesn't that require testing it on the same basis as other platforms?\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 11:33:17 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Andrew Dunstan <andrew@dunslane.net> writes:\n> On 10/25/21 10:23, Tom Lane wrote:\n>> (Hmmm ... but disk space could\n>> become a problem, particularly on older machines with not so much\n>> disk. Do we really need to maintain a separate checkout for each\n>> branch? It seems like a fresh checkout from the repo would be\n>> little more expensive than the current copy-a-checkout process.)\n\n> If you set it up with these settings then the disk space used is minimal:\n> git_use_workdirs => 1,\n> rm_worktrees => 1,\n\nMaybe we should make those the defaults? AFAICS the current\ndefault setup uses circa 200MB per back branch, even between runs.\nI'm not sure what that is buying us.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 11:38:51 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 2021-Oct-25, Tom Lane wrote:\n\n> It's also unclear to me why we'd leave Windows out of this discussion.\n> We keep saying we want to encourage Windows-based hackers to contribute,\n> so doesn't that require testing it on the same basis as other platforms?\n\nTesting of in-support branches, sure -- I don't propose to break that.\nBut this is all about providing *some* server against which to test\nclient-side changes with, right? Not to test the old servers\nthemselves. Looking at Amit K's \"Postgres person of the week\" interview[1]\nand remembering conversations with David Rowley, Windows hackers seem\nperfectly familiar with getting Linux builds going, so we wouldn't need\nto force MSVC fixes in order for them to have old servers available.\n\nBut anyway, I was thinking that the fixes required for MSVC buildability\nwere quite invasive, but on looking again they don't seem all that\nbad[2], so I withdraw that comment.\n\nI do think you have moved the goalposts: to reiterate what I said above,\nI thought what we wanted was to have *some* server in order to test\nclient-side changes with; not to be able to get a server running on\nevery possible platform. I'm not really on board with the idea that old\nbranches have to be buildable everywhere all the time.\n\n[1] https://postgresql.life/post/amit_kapila/\n[2] e.g., commit 2b1394fc2b52a2573d08aa626e7b49568f27464e\n\n-- \nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\n\n\n","msg_date":"Mon, 25 Oct 2021 13:25:04 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Alvaro Herrera <alvherre@alvh.no-ip.org> writes:\n> I do think you have moved the goalposts: to reiterate what I said above,\n> I thought what we wanted was to have *some* server in order to test\n> client-side changes with; not to be able to get a server running on\n> every possible platform. I'm not really on board with the idea that old\n> branches have to be buildable everywhere all the time.\n\nAgreed, that might be too much work compared to the value. But if we're\nto be selective about support for this, I'm unclear on how we decide\nwhich platforms are supported --- and, more importantly, how we keep\nthat list up to date over time.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 12:43:15 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Hi,\n\nOn 2021-10-22 19:30:25 -0400, Tom Lane wrote:\n> Yeah. I checked into when it was that we dropped pre-8.0 support\n> from pg_dump, and the answer is just about five years ago (64f3524e2).\n> So moving the bar forward by five releases isn't at all out of line.\n> 8.4 would be eight years past EOL by the time v15 comes out.\n\nI'd really like us to adopt a \"default\" policy on this. I think it's a waste\nto spend time every few years arguing what exact versions to drop. I'd much\nrather say that, unless there are concrete reasons to deviate from that, we\nprovide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\nfor 5 releases or something like that.\n\nIt's fine to not actually spend the time to excise support for old versions\nevery release if not useful, but we should be able to \"just do it\" whenever\nversion compat is a meaningful hindrance.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 09:56:20 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Hi,\n\nOn 2021-10-25 10:23:40 -0400, Tom Lane wrote:\n> Also, I concur with Andrew's point that we'd really have to have\n> buildfarm support. However, this might not be as bad as it seems.\n> In principle we might just need to add resurrected branches back to\n> the branches_to_build list. Given my view of what the back-patching\n> policy ought to be, a new build in an old branch might only be\n> required a couple of times a year, which would not be an undue\n> investment of buildfarm resources.\n\nFWIW, if helpful I could easily specify a few additional branches to some of\nmy buildfarm animals. Perhaps serinus/flaviventris (snapshot gcc wo/w\noptimizations) so we'd see problems coming early? I could also add\nrecent-clang one.\n\nI think doing this to a few designated animals is a better idea than wasting\ncycles and space on a lot of animals.\n\n\n> It seems like a fresh checkout from the repo would be little more expensive\n> than the current copy-a-checkout process.)\n\nI haven't looked in detail, but from what I've seen in the logs the\nis-there-anything-new check is already not cheap, and does a checkout / update\nof the git directory.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 10:06:57 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-22 19:30:25 -0400, Tom Lane wrote:\n>> Yeah. I checked into when it was that we dropped pre-8.0 support\n>> from pg_dump, and the answer is just about five years ago (64f3524e2).\n>> So moving the bar forward by five releases isn't at all out of line.\n>> 8.4 would be eight years past EOL by the time v15 comes out.\n\n> I'd really like us to adopt a \"default\" policy on this. I think it's a waste\n> to spend time every few years arguing what exact versions to drop. I'd much\n> rather say that, unless there are concrete reasons to deviate from that, we\n> provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\n> for 5 releases or something like that.\n\nI agree with considering something like that to be the minimum support\npolicy, but the actual changes need a bit more care. For example, when\nwe last did this, the technical need was just to drop pre-7.4 versions,\nbut we chose to make the cutoff 8.0 on the grounds that that was more\nunderstandable to users [1]. In the same way, I'm thinking of moving the\ncutoff to 9.0 now, although 8.4 would be sufficient from a technical\nstandpoint.\n\nOTOH, in the new world of one-part major versions, it's less clear that\nthere will be obvious division points for future cutoff changes. Maybe\nversions-divisible-by-five would work? Or versions divisible by ten,\nbut experience so far suggests that we'll want to move the cutoff more\noften than once every ten years.\n\n\t\t\tregards, tom lane\n\n[1] https://www.postgresql.org/message-id/flat/2661.1475849167%40sss.pgh.pa.us\n\n\n","msg_date":"Mon, 25 Oct 2021 13:09:43 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-25 10:23:40 -0400, Tom Lane wrote:\n>> It seems like a fresh checkout from the repo would be little more expensive\n>> than the current copy-a-checkout process.)\n\n> I haven't looked in detail, but from what I've seen in the logs the\n> is-there-anything-new check is already not cheap, and does a checkout / update\n> of the git directory.\n\nYeah, you probably need a checkout to apply the rule about don't rebuild\nafter documentation-only changes. But it seems like the case where the\nbranch tip hasn't moved at all could be optimized fairly easily. I'm not\nsure it's worth the trouble to add code for that given our current usage\nof the buildfarm; but if we were to start tracking branches that only\nchange a couple of times a year, it would be.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 13:14:19 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Hi,\n\nOn 2021-10-25 12:43:15 -0400, Tom Lane wrote:\n> Agreed, that might be too much work compared to the value. But if we're\n> to be selective about support for this, I'm unclear on how we decide\n> which platforms are supported --- and, more importantly, how we keep\n> that list up to date over time.\n\nI honestly think that if we just test on linux with a single distribution,\nwe're already covering most of the benefit. From memory there have been two\nrough classes of doesn't-build-anymore:\n\n1) New optimizations / warnings. At least between gcc and clang, within a year\n or two, most of the issues end up being visible with the other compiler\n too. These aren't particularly distribution / OS specific.\n\n2) Library dependencies cause problems, like the ssl detection mentioned\n elsewhere in this thread. This is also not that OS dependent. It's also not\n that clear that we can do something about the issues with a reasonable\n amount of effort in all cases. It's easy enough if it's just a minor\n configure fix, but we'd not want to backpatch larger SSL changes or such.\n\n\nMaybe there's also a case for building older releases with msvc, but that\nseems like a pain due to the msvc project generation needing to support a\nspecific version of msvc.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 10:17:20 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Hi,\n\nOn 2021-10-25 13:09:43 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> > I'd really like us to adopt a \"default\" policy on this. I think it's a waste\n> > to spend time every few years arguing what exact versions to drop. I'd much\n> > rather say that, unless there are concrete reasons to deviate from that, we\n> > provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\n> > for 5 releases or something like that.\n> \n> I agree with considering something like that to be the minimum support\n> policy, but the actual changes need a bit more care. For example, when\n> we last did this, the technical need was just to drop pre-7.4 versions,\n> but we chose to make the cutoff 8.0 on the grounds that that was more\n> understandable to users [1]. In the same way, I'm thinking of moving the\n> cutoff to 9.0 now, although 8.4 would be sufficient from a technical\n> standpoint.\n\nI think that'd be less of a concern if we had a documented policy\nsomewhere. It'd not be hard to include a version table in that policy to make\nit easier to understand. We could even add it to the table in\nhttps://www.postgresql.org/support/versioning/ or something similar.\n\n\n> OTOH, in the new world of one-part major versions, it's less clear that\n> there will be obvious division points for future cutoff changes. Maybe\n> versions-divisible-by-five would work?\n\nI think that's more confusing than helpful, because the support timeframes\nthen differ between releases. It's easier to just subtract a number of major\nreleases for from a specific major version. Especially if there's a table\nsomewhere.\n\n\n> Or versions divisible by ten, but experience so far suggests that we'll want\n> to move the cutoff more often than once every ten years.\n\nYes, I think that'd be quite a bit too restrictive.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 10:24:13 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 13:06, Andres Freund wrote:\n> Hi,\n>\n> On 2021-10-25 10:23:40 -0400, Tom Lane wrote:\n>> Also, I concur with Andrew's point that we'd really have to have\n>> buildfarm support. However, this might not be as bad as it seems.\n>> In principle we might just need to add resurrected branches back to\n>> the branches_to_build list. Given my view of what the back-patching\n>> policy ought to be, a new build in an old branch might only be\n>> required a couple of times a year, which would not be an undue\n>> investment of buildfarm resources.\n> FWIW, if helpful I could easily specify a few additional branches to some of\n> my buildfarm animals. Perhaps serinus/flaviventris (snapshot gcc wo/w\n> optimizations) so we'd see problems coming early? I could also add\n> recent-clang one.\n>\n> I think doing this to a few designated animals is a better idea than wasting\n> cycles and space on a lot of animals.\n\n\nRight now the server will only accept results for something in\nbranches_of_interest.txt. So we would need to modify that.\n\n\nI tend to agree that we don't need a whole lot of cross platform testing\nhere.\n\n\n>\n>\n>> It seems like a fresh checkout from the repo would be little more expensive\n>> than the current copy-a-checkout process.)\n> I haven't looked in detail, but from what I've seen in the logs the\n> is-there-anything-new check is already not cheap, and does a checkout / update\n> of the git directory.\n>\n>\n\nIf you have removed the work tree (with the \"rm_worktrees => 1\" setting)\nthen it restores it by doing a checkout. It then does a \"git fetch\", and\nthen as you say looks to see if there is anything new. If you know of a\nbetter way to manage it then please let me know. On crake (which is\nactually checking out four different repos) the checkout step typically\ntakes one or two seconds.\n\n\nCopying the work tree can take a few seconds - to avoid that on\nUnix/msys use vpath builds.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 16:29:11 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Anyway, to get back to the original point ...\n\nNo one has spoken against moving up the cutoff for pg_dump support,\nso I did a very quick pass to see how much code could be removed.\nThe answer is right about 1000 lines, counting both pg_dump and\npg_upgrade, so it seems like it's worth doing independently of the\nunnest() issue.\n\nThe attached is just draft-quality, because I don't really want\nto pursue the point until after committing the pg_dump changes\nbeing discussed in the other thread. If I push this first it'll\nbreak a lot of those patches. (Admittedly, pushing those first\nwill break this one, but this one is a lot easier to re-do.)\n\nBTW, while looking at pg_upgrade I chanced to notice\ncheck_for_isn_and_int8_passing_mismatch(), which seems like it's\nnot well thought out at all. It's right that contrib/isn will\nnot upgrade nicely if the target cluster has a different\nfloat8_pass_by_value setting from the source. What's wrong is\nthe assumption that no other extension has the same issue.\nWe invented and publicized the \"LIKE type\" option for CREATE TYPE\nprecisely so that people could build types that act just like isn,\nso it seems pretty foolish to imagine that no one has done so.\n\nI think we should nuke check_for_isn_and_int8_passing_mismatch()\nand just refuse to upgrade if float8_pass_by_value differs, full stop.\nI can see little practical need to allow that case.\n\n\t\t\tregards, tom lane","msg_date":"Mon, 25 Oct 2021 18:52:18 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Oct 25, 2021 at 11:38:51AM -0400, Tom Lane wrote:\n> Andrew Dunstan <andrew@dunslane.net> writes:\n> > On 10/25/21 10:23, Tom Lane wrote:\n> >> (Hmmm ... but disk space could\n> >> become a problem, particularly on older machines with not so much\n> >> disk. Do we really need to maintain a separate checkout for each\n> >> branch? It seems like a fresh checkout from the repo would be\n> >> little more expensive than the current copy-a-checkout process.)\n> \n> > If you set it up with these settings then the disk space used is minimal:\n> > �� � git_use_workdirs => 1,\n> > �� � rm_worktrees => 1,\n> \n> Maybe we should make those the defaults? AFAICS the current\n> default setup uses circa 200MB per back branch, even between runs.\n> I'm not sure what that is buying us.\n\nMaybe git's shared/\"alternates\" would be helpful to minimize the size of\n.git/objects?\n\nI'm not sure - it looks like the BF client does its own stuff with symlinks.\nIs that for compatibility with old git ?\nhttps://github.com/PGBuildFarm/client-code/blob/main/PGBuild/SCM.pm\n\nIf you \"clone\" a local location, it uses hard links by default.\nIf you use --shared or --reference, then it uses references to the configured\n\"alternates\", if any.\n\nIn both cases, .git/objects requires no additional space (but the \"checked out\"\ncopy still takes up however much space).\n\n$ mkdir tmp\n$ git clone --quiet ./postgresql tmp/pg\n$ du -sh tmp/pg\n492M tmp/pg\n\n$ rm -fr tmp/pg\n$ git clone --quiet --shared ./postgresql tmp/pg\n$ du -sh tmp/pg\n124M tmp/pg\n\n-- \nJustin\n\n\n","msg_date":"Mon, 25 Oct 2021 18:12:56 -0500","msg_from":"Justin Pryzby <pryzby@telsasoft.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 19:12, Justin Pryzby wrote:\n> On Mon, Oct 25, 2021 at 11:38:51AM -0400, Tom Lane wrote:\n>> Andrew Dunstan <andrew@dunslane.net> writes:\n>>> On 10/25/21 10:23, Tom Lane wrote:\n>>>> (Hmmm ... but disk space could\n>>>> become a problem, particularly on older machines with not so much\n>>>> disk. Do we really need to maintain a separate checkout for each\n>>>> branch? It seems like a fresh checkout from the repo would be\n>>>> little more expensive than the current copy-a-checkout process.)\n>>> If you set it up with these settings then the disk space used is minimal:\n>>> git_use_workdirs => 1,\n>>> rm_worktrees => 1,\n>> Maybe we should make those the defaults? AFAICS the current\n>> default setup uses circa 200MB per back branch, even between runs.\n>> I'm not sure what that is buying us.\n> Maybe git's shared/\"alternates\" would be helpful to minimize the size of\n> .git/objects?\n>\n> I'm not sure - it looks like the BF client does its own stuff with symlinks.\n> Is that for compatibility with old git ?\n> https://github.com/PGBuildFarm/client-code/blob/main/PGBuild/SCM.pm\n\n\nIt's actually based on the git contrib script git-new-workdir. And using\nit is the default (except on Windows, where it doesn't work due to\nissues with symlinking plain files :-( )\n\nSince what we have is not broken I'm not inclined to fix it.\n\nThe issue Tom was complaining about is different, namely the storage for\neach branch's working tree. As I mentioned upthread, you can alleviate\nthat by setting \"rm_worktrees => 1\" in your config. That works\neverywhere, including Windows, and will be the default in the next\nbuildfarm release.\n\n\ncheers\n\n\nandrew\n\n\n-- \n\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 26 Oct 2021 13:41:32 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 10/25/21 13:09, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n>> On 2021-10-22 19:30:25 -0400, Tom Lane wrote:\n>>> Yeah. I checked into when it was that we dropped pre-8.0 support\n>>> from pg_dump, and the answer is just about five years ago (64f3524e2).\n>>> So moving the bar forward by five releases isn't at all out of line.\n>>> 8.4 would be eight years past EOL by the time v15 comes out.\n>> I'd really like us to adopt a \"default\" policy on this. I think it's a waste\n>> to spend time every few years arguing what exact versions to drop. I'd much\n>> rather say that, unless there are concrete reasons to deviate from that, we\n>> provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\n>> for 5 releases or something like that.\n> I agree with considering something like that to be the minimum support\n> policy, but the actual changes need a bit more care. For example, when\n> we last did this, the technical need was just to drop pre-7.4 versions,\n> but we chose to make the cutoff 8.0 on the grounds that that was more\n> understandable to users [1]. In the same way, I'm thinking of moving the\n> cutoff to 9.0 now, although 8.4 would be sufficient from a technical\n> standpoint.\n>\n> OTOH, in the new world of one-part major versions, it's less clear that\n> there will be obvious division points for future cutoff changes. Maybe\n> versions-divisible-by-five would work? Or versions divisible by ten,\n> but experience so far suggests that we'll want to move the cutoff more\n> often than once every ten years.\n>\n> \t\n\n\npg_upgrade claims to be able to operate on 8.4, which might be all the\nbetter for some regular testing (which this could enable), so that seems\nto me more like where the cutoff should be at least for this round.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 26 Oct 2021 13:59:34 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"I was thinking a bit about formulating a policy for pg_dump backward\ncompatibility, based on the discussions in this thread.\n\nPremises and preparatory thoughts:\n\n- Users (and developers) want pg_dump to support server versions that\n are much older than non-EOL versions.\n\n- Less critically, much-longer backward compatibility has also\n historically been provided for psql, so keeping those two the same\n would make sense.\n\n- The policy for other client-side tools (list at [0]) is less clear\n and arguably less important. I suggest we focus on pg_dump and psql\n first, and then we can decide for the rest whether they want to\n match a longer window, a shorter window, or a different policy\n altogether (e.g., ecpg).\n\n- If we are going to maintain compatibility with very old server\n versions, we need to make sure the older server versions can at\n least still be built while an allegedly-compatible client tool is\n under support.\n\n[0]: https://www.postgresql.org/docs/devel/reference-client.html\n\nProposal:\n\n* pg_dump and psql will maintain compatibility with servers at least\n ten major releases back.\n\nThis assumes a yearly major release cadence.\n\nI use the count of major releases here instead of some number of\nyears, as was previously discussed, for two reasons. First, it makes\ncomputing the cutoff easier, because you are not bothered by whether\nsome old release was released a few weeks before or after the\nequivalent date in the current year for the new release. Second,\nthere is no ambiguity about what happens during the lifetime of a\nmajor release: If major release $NEW supports major release $OLD at\nthe time of $NEW's release, then that stays the same for the whole\nlife of $NEW; we don't start dropping support for $OLD in $NEW.5\nbecause a year has passed.\n\nI say \"at least\" because I wouldn't go around aggressively removing\nsupport for old releases. If $NEW is supposed to support 9.5 but\nthere is code that says `if (version > 9.4)`, I would not s/9.4/9.5/\nthat unless that code is touched for other reasons.\n\nThen ...\n\n* We keep old major release branches buildable as long as a new major\n release that has support for that old release is under support.\n\nBuildable for this purpose means just enough that you can use it to\ntest pg_dump and psql. This probably includes being able to run make\ninstallcheck and use pg_dump and psql against the regression database.\nIt does not require support for any additional build-time options that\nare not required for this purpose (e.g., new OpenSSL releases).\nConversely, it should be buildable with default compiler options. For\nexample, if it fails to build and test cleanly unless you use -O0,\nthat should be fixed. Fixes in very-old branches should normally be\nbackpatches that have stabilized in under-support branches. Changes\nthat silence compiler warnings in newer compilers are by themselves\nnot considered a backpatch-worthy fix.\n\n(In some cases, the support window of typical compilers should be\nconsidered. If adding support for a very new compiler with new\naggressive optimizations turns out to be too invasive, then that\ncompiler might simply be declared not supported for that release. But\nwe should strive to support at least one compiler that still has some\nupstream support.)\n\nThis keep-buildable effort is on an as-needed basis. There is no\nrequirement to keep the buildability current at all times, and there\nis no requirement to keep all platforms working at all times.\nObviously, any changes made to improve buildability should not\nknowingly adversely affect other platforms.\n\n(The above could be reconsidered if buildfarm support is available,\nbut I don't consider that necessary and wouldn't want to wait for it.)\n\nThere is no obligation on anyone backpatching fixes to supported\nbranches to also backpatch them to keep-buildable branches. It is up\nto those working on pg_dump/psql and requiring testing against old\nversions to pick available fixes and apply them to keep-buildable\nbranches as needed.\n\nFinally, none of this is meant to imply that there will be any\nreleases, packages, security support, production support, or community\nsupport for keep-buildable branches. This is a Git-repo-only,\ndeveloper-focusing effort.\n\nExample under this proposal:\n\nPG 15 supports PG 9.2\nPG 14 supports PG 9.1\nPG 13 supports PG 9.0\nPG 12 supports PG 8.4\nPG 11 supports PG 8.3\nPG 10 supports PG 8.2\n\nIn practice, the effort can focus on keeping the most recent cutoff\nrelease buildable. So in the above example, we really only need to\nkeep PG >=9.2 buildable to support ongoing development. The chances\nthat some needs to touch code pertaining to older versions in\nbackbranches is lower, so those really would need to be dealt with\nvery rarely.\n\n\nThe parent message has proposed to remove support for PG <9.0 from\nmaster. But I think that was chosen mainly because it was a round\nnumber. I suggest we pick a cutoff based on years, as I had\ndescribed, and then proceed with that patch.\n\n\n","msg_date":"Thu, 2 Dec 2021 11:01:47 +0100","msg_from":"Peter Eisentraut <peter.eisentraut@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Thu, Dec 2, 2021 at 5:01 AM Peter Eisentraut\n<peter.eisentraut@enterprisedb.com> wrote:\n> * pg_dump and psql will maintain compatibility with servers at least\n> ten major releases back.\n>\n> * We keep old major release branches buildable as long as a new major\n> release that has support for that old release is under support.\n>\n> Buildable for this purpose means just enough that you can use it to\n> test pg_dump and psql. This probably includes being able to run make\n> installcheck and use pg_dump and psql against the regression database.\n> It does not require support for any additional build-time options that\n> are not required for this purpose (e.g., new OpenSSL releases).\n> Conversely, it should be buildable with default compiler options. For\n> example, if it fails to build and test cleanly unless you use -O0,\n> that should be fixed. Fixes in very-old branches should normally be\n> backpatches that have stabilized in under-support branches. Changes\n> that silence compiler warnings in newer compilers are by themselves\n> not considered a backpatch-worthy fix.\n\nSounds reasonable. It doesn't really make sense to insist that the\ntools have to be compatible with releases that most developers can't\nactually build.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 2 Dec 2021 06:54:04 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\n> Proposal:\n\n> * pg_dump and psql will maintain compatibility with servers at least\n> ten major releases back.\n> * We keep old major release branches buildable as long as a new major\n> release that has support for that old release is under support.\n\n> This assumes a yearly major release cadence.\n\nIf the point is to not have to count dates carefully, why does the cadence\nmatter?\n\n> I say \"at least\" because I wouldn't go around aggressively removing\n> support for old releases. If $NEW is supposed to support 9.5 but\n> there is code that says `if (version > 9.4)`, I would not s/9.4/9.5/\n> that unless that code is touched for other reasons.\n\nI can get behind something roughly like this, but I wonder if it wouldn't\nbe better to formulate the policy in a reactive way, i.e. when X happens\nwe'll do Y. If we don't plan to proactively remove some code every year,\nthen it seems like the policy really is more like \"when something breaks,\nthen we'll make an attempt to keep it working if the release is less than\nten majors back; otherwise we'll declare that release no longer\nbuildable.\"\n\nHowever, this'd imply continuing to test against releases that are out of\nthe ten-year window but have not yet been found to be broken. Not sure\nif that's a useful expenditure of test resources or not.\n\n> Buildable for this purpose means just enough that you can use it to\n> test pg_dump and psql. This probably includes being able to run make\n> installcheck and use pg_dump and psql against the regression database.\n> It does not require support for any additional build-time options that\n> are not required for this purpose (e.g., new OpenSSL releases).\n\nI agree with the idea of being conservative about what outside\ndependencies we will worry about for \"buildable\" old versions.\n(Your nearby message about Python breakage is a good example of\nwhy we must limit that.) But I wonder about, say, libxml or libicu,\nor even if we can afford to drop all the non-plpgsql PLs. An\nexample of why that seems worrisome is that it's not clear we'd\nhave any meaningful coverage of transforms in pg_dump with no PLs.\nI don't have any immediate proposal here, but it seems like an area\nthat needs some thought and specific policy.\n\n> Example under this proposal:\n\n> PG 15 supports PG 9.2\n> PG 14 supports PG 9.1\n> PG 13 supports PG 9.0\n> PG 12 supports PG 8.4\n> PG 11 supports PG 8.3\n> PG 10 supports PG 8.2\n\nI was going to express concern about having to resurrect branches\nback to 8.2, but:\n\n> In practice, the effort can focus on keeping the most recent cutoff\n> release buildable. So in the above example, we really only need to\n> keep PG >=9.2 buildable to support ongoing development. The chances\n> that some needs to touch code pertaining to older versions in\n> backbranches is lower, so those really would need to be dealt with\n> very rarely.\n\nOK. Also, when you do need to check that, there are often other ways\nthan rebuilding the old branch on modern platforms --- people may\nwell have still-executable builds laying about, even if rebuilding\nfrom source would be problematic.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 02 Dec 2021 12:30:45 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 12/2/21 12:30, Tom Lane wrote:\n>\n>> In practice, the effort can focus on keeping the most recent cutoff\n>> release buildable. So in the above example, we really only need to\n>> keep PG >=9.2 buildable to support ongoing development. The chances\n>> that some needs to touch code pertaining to older versions in\n>> backbranches is lower, so those really would need to be dealt with\n>> very rarely.\n> OK. Also, when you do need to check that, there are often other ways\n> than rebuilding the old branch on modern platforms --- people may\n> well have still-executable builds laying about, even if rebuilding\n> from source would be problematic.\n>\n> \t\t\t\n\n\n\nI have a very old fedora instance where I can build every release back\nto 7.2 :-) And with only slight massaging for the very old releases,\nthese builds run on my Fedora 34 development system. Certainly 8.2 and\nup wouldn't be a problem. Currently I have only tested building without\nany extra libraries/PLs, but I can look at other combinations. So, long\nstory short this is fairly doable at least in some environments. This\nprovides a good use case for the work I have been doing on backwards\ncompatibility of the TAP framework. I need to get back to that now that\nthe great module namespace adjustment has settled down.\n\n\ncheers\n\n\nandrew\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Thu, 2 Dec 2021 15:46:09 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Hi,\n\nOn 2021-12-02 11:01:47 +0100, Peter Eisentraut wrote:\n> - The policy for other client-side tools (list at [0]) is less clear\n> and arguably less important. I suggest we focus on pg_dump and psql\n> first, and then we can decide for the rest whether they want to\n> match a longer window, a shorter window, or a different policy\n> altogether (e.g., ecpg).\n\nI think we should at least include pg_upgrade in this as well, it's pretty\nclosely tied to at least pg_dump.\n\n\n> * pg_dump and psql will maintain compatibility with servers at least\n> ten major releases back.\n\nPersonally I think that's too long... It boils down keeping branches buildable\nfor ~15 years after they've been released. That strikes me as pretty far into\ndiminishing-returns, and steeply increasing costs, territory.\n\nI realize it's more complicated for users, but a policy based on supporting a\ncertain number of out-of-support branches calculated from the newest major\nversion is more realistic. I'd personally go for something like newest-major -\n7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\nsupport a few more. I think there's a considerable advantage of having one\ncutoff date across all branches.\n\nThat's not to say we'd remove support for older versions from back\nbranches. Just that we don't ever consider them supported (or test them) once\nbelow the cutoff.\n\n\n> I use the count of major releases here instead of some number of\n> years, as was previously discussed, for two reasons. First, it makes\n> computing the cutoff easier, because you are not bothered by whether\n> some old release was released a few weeks before or after the\n> equivalent date in the current year for the new release. Second,\n> there is no ambiguity about what happens during the lifetime of a\n> major release: If major release $NEW supports major release $OLD at\n> the time of $NEW's release, then that stays the same for the whole\n> life of $NEW; we don't start dropping support for $OLD in $NEW.5\n> because a year has passed.\n\nMakes sense.\n\n\n> * We keep old major release branches buildable as long as a new major\n> release that has support for that old release is under support.\n\n> Buildable for this purpose means just enough that you can use it to\n> test pg_dump and psql. This probably includes being able to run make\n> installcheck and use pg_dump and psql against the regression database.\n\nI think we should explicitly limit the number of platforms we care about for\nthis purpose. I don't think we should even try to keep 8.2 compile on AIX or\nwhatnot.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 2 Dec 2021 14:16:07 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 02.12.21 18:30, Tom Lane wrote:\n>> This assumes a yearly major release cadence.\n> \n> If the point is to not have to count dates carefully, why does the cadence\n> matter?\n\nIf we were to change the release cadence, then it would be appropriate \nto review this policy.\n\n> I can get behind something roughly like this, but I wonder if it wouldn't\n> be better to formulate the policy in a reactive way, i.e. when X happens\n> we'll do Y. If we don't plan to proactively remove some code every year,\n> then it seems like the policy really is more like \"when something breaks,\n> then we'll make an attempt to keep it working if the release is less than\n> ten majors back; otherwise we'll declare that release no longer\n> buildable.\"\n\nThis sounds like it would give license to accidentally break support for \nold releases in the code and only fix them if someone complains. That's \nnot really what I would be aiming for.\n\n> I agree with the idea of being conservative about what outside\n> dependencies we will worry about for \"buildable\" old versions.\n> (Your nearby message about Python breakage is a good example of\n> why we must limit that.) But I wonder about, say, libxml or libicu,\n> or even if we can afford to drop all the non-plpgsql PLs. An\n> example of why that seems worrisome is that it's not clear we'd\n> have any meaningful coverage of transforms in pg_dump with no PLs.\n> I don't have any immediate proposal here, but it seems like an area\n> that needs some thought and specific policy.\n\nYeah, I think questions like this will currently quickly lead to dead \nends. We are talking 5 years this, 10 years that here. Everybody else \n(apart from RHEL) is talking at best in the range 3-5 years. We will \nhave to figure this out as we go.\n\n\n","msg_date":"Fri, 3 Dec 2021 17:19:47 +0100","msg_from":"Peter Eisentraut <peter.eisentraut@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 02.12.21 23:16, Andres Freund wrote:\n> I think we should at least include pg_upgrade in this as well, it's pretty\n> closely tied to at least pg_dump.\n\nright\n\n>> * pg_dump and psql will maintain compatibility with servers at least\n>> ten major releases back.\n> \n> Personally I think that's too long... It boils down keeping branches buildable\n> for ~15 years after they've been released. That strikes me as pretty far into\n> diminishing-returns, and steeply increasing costs, territory.\n\nWell, it is a lot, but it's on the order of what we have historically \nprovided.\n\n> I realize it's more complicated for users, but a policy based on supporting a\n> certain number of out-of-support branches calculated from the newest major\n> version is more realistic. I'd personally go for something like newest-major -\n> 7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\n> support a few more. I think there's a considerable advantage of having one\n> cutoff date across all branches.\n\nI'm not sure it will be clear what this would actually mean. Assume \nPG11 supports back to 9.4 (14-7) now, but when PG15 comes out, we drop \n9.4 support. But the PG11 code hasn't changed, and PG9.4 hasn't changed, \nso it will most likely still work. Then we have messaging that is out \nof sync with reality. I can see the advantage of this approach, but the \ncommunication around it might have to be refined.\n\n> I think we should explicitly limit the number of platforms we care about for\n> this purpose. I don't think we should even try to keep 8.2 compile on AIX or\n> whatnot.\n\nIt's meant to be developer-facing, so only for platforms that developers \nuse. I think that can police itself, if we define it that way.\n\n\n","msg_date":"Fri, 3 Dec 2021 17:29:41 +0100","msg_from":"Peter Eisentraut <peter.eisentraut@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\n> [ policy requiring that 9.2 and up be kept buildable, as of today ]\n\nI experimented to see what this would entail exactly. Using\ncurrent macOS (Apple clang version 13.0.0) on M1 hardware,\nI built with minimal configure options (--enable-debug --enable-cassert)\nand ran the core regression tests. I found that commit\n1c0cf52b3 (Use return instead of exit() in configure) is needed\nin 9.4 and before, else we don't get through configure.\nThat's the only fix needed to get a clean build in 9.4 and 9.3.\n9.2 shows several compiler warnings, the scarier ones of which could\nbe cleaned up by back-patching c74d586d2 (Fix function return type\nconfusion). The remainder are variable-may-be-used-uninitialized\nwarnings, which I think people are accustomed to ignoring in\ndubious cases. In any case, I failed to get rid of them without\nback-patching 71450d7fd (Teach compiler that ereport(>=ERROR) does\nnot return), which seems like a bridge too far.\n\nI also tried 9.1, but it has multiple compile-time problems:\n* fails to select a spinlock implementation\n* \"conflicting types for 'base_yylex'\"\n* strange type-conflict warnings in zlib calls\n\nSo at least on this platform, there are solid technical reasons\nto select 9.2 not 9.1 as the cutoff.\n\nObviously, we might find some other things to fix if we checked\nwith other compilers, or tested more than the core tests.\nBut this much seems quite doable, and it's probably prerequisite\nfor any further testing.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 03 Dec 2021 12:10:07 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 12/3/21 12:10, Tom Lane wrote:\n> Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\n>> [ policy requiring that 9.2 and up be kept buildable, as of today ]\n> I experimented to see what this would entail exactly. Using\n> current macOS (Apple clang version 13.0.0) on M1 hardware,\n> I built with minimal configure options (--enable-debug --enable-cassert)\n> and ran the core regression tests. \n\n\nI've mentioned my efforts on fedora previously. But like you I used a\nminimal configuration. So what would be reasonable to test? I know you\nmentioned building with perl and python upthread so we could possibly\ntest transforms. Anything else? I don't think we need to worry about all\nthe authentication-supporting options. XML/XSLT maybe.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Fri, 3 Dec 2021 12:28:11 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Andrew Dunstan <andrew@dunslane.net> writes:\n> On 12/3/21 12:10, Tom Lane wrote:\n>> I experimented to see what this would entail exactly. Using\n>> current macOS (Apple clang version 13.0.0) on M1 hardware,\n>> I built with minimal configure options (--enable-debug --enable-cassert)\n>> and ran the core regression tests. \n\n> I've mentioned my efforts on fedora previously. But like you I used a\n> minimal configuration. So what would be reasonable to test? I know you\n> mentioned building with perl and python upthread so we could possibly\n> test transforms. Anything else? I don't think we need to worry about all\n> the authentication-supporting options. XML/XSLT maybe.\n\nNot sure. I think we should evaluate based on\n1. how integral is the option, ie how much PG code can't we test if\n we don't enable it.\n2. how stable is the referenced code.\n\nPoint 2 makes me want to exclude both Python and OpenSSL, as they've\nboth proven to be moving API targets. If we want to have tests for\ntransform modules, plperl would be sufficient for that, and perl seems\nto be a lot more stable than python. libxml is pretty morib^H^H^Hstable,\nbut on the other hand it seems quite noncritical for the sorts of tests\nwe want to run against old servers, so I'd be inclined to exclude it.\n\nLooking through the other configure options, the only one that I find\nto be a hard call is --enable-nls. In theory this shouldn't be\ncritical for testing pg_dump or psql ... but you never know, and it\nhasn't been a stability problem. Every other one I think we could\nignore for these purposes. At some point --with-icu might become\ninteresting, but it isn't yet relevant to any out-of-support\nbranches, so we can leave that call for another day.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 03 Dec 2021 13:09:31 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\n> On 02.12.21 23:16, Andres Freund wrote:\n>> I realize it's more complicated for users, but a policy based on supporting a\n>> certain number of out-of-support branches calculated from the newest major\n>> version is more realistic. I'd personally go for something like newest-major -\n>> 7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\n>> support a few more. I think there's a considerable advantage of having one\n>> cutoff date across all branches.\n\n> I'm not sure it will be clear what this would actually mean. Assume \n> PG11 supports back to 9.4 (14-7) now, but when PG15 comes out, we drop \n> 9.4 support. But the PG11 code hasn't changed, and PG9.4 hasn't changed, \n> so it will most likely still work. Then we have messaging that is out \n> of sync with reality. I can see the advantage of this approach, but the \n> communication around it might have to be refined.\n\nI don't find this suggestion to be an improvement over Peter's original\nformulation, for two reasons:\n\n* I'm not convinced that it saves us any actual work; as you say, the\ncode doesn't stop working just because we declare it out-of-support.\n\n* There's a real-world use-case underneath here. If somewhere you've\ndiscovered a decades-old server that you need to upgrade, and current\npg_dump won't dump from it, you would like it to be well-defined\nwhich intermediate pg_dump versions you can use. So if 10.19 can\ndump from that hoary server, it would not be nice if 10.20 can't;\nnor if the documentation lies to you about that based on which minor\nversion you happen to consult.\n\n>> I think we should explicitly limit the number of platforms we care about for\n>> this purpose. I don't think we should even try to keep 8.2 compile on AIX or\n>> whatnot.\n\n> It's meant to be developer-facing, so only for platforms that developers \n> use. I think that can police itself, if we define it that way.\n\nI agree that if you care about doing this sort of test on platform X,\nit's up to you to patch for that. I think Andres' concern is about\nthe amount of committer bandwidth that might be needed to handle\nsuch patches submitted by non-committers. However, based on the\nexperiment I just ran, I think it's not really likely to be a big deal:\nthere are not that many problems, and most of them just amount to\nback-patching something that originally wasn't back-patched.\n\nWhat's most likely to happen IMO is that committers will just start\nback-patching essential portability fixes into out-of-support-but-\nstill-in-the-buildability-window branches, contemporaneously with\nthe original fix. Yeah, that does mean more committer effort,\nbut only for a very small number of patches.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Fri, 03 Dec 2021 13:30:31 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Fri, Dec 3, 2021 at 1:30 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> What's most likely to happen IMO is that committers will just start\n> back-patching essential portability fixes into out-of-support-but-\n> still-in-the-buildability-window branches, contemporaneously with\n> the original fix. Yeah, that does mean more committer effort,\n> but only for a very small number of patches.\n\nI agree. I think that's exactly what we want to have happen, and if a\ngiven policy won't have exactly this result then the policy needs\nadjusting.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 3 Dec 2021 15:46:04 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"I ran a new set of experiments concerning building back branches\non modern platforms, this time trying Fedora 35 (gcc 11.2.1)\non x86_64. I widened the scope of the testing a bit by adding\n\"--enable-nls --with-perl\" and running check-world not just the\ncore tests. Salient results:\n\n* Everything back to 9.2 passes the test, although with more\nand more compile warnings the further back you go.\n\n* 9.1 fails with \"conflicting types for 'base_yylex'\", much as\nI saw on macOS except it's a hard error on this compiler.\n\n* Parallel check-world is pretty unreliable before v10 (I knew\nthis already, actually). But without parallelism, it's fine.\n\nBased on these results, I think maybe we should raise our ambitions\na bit compared to Peter's original proposal. Specifically,\nI wonder if it wouldn't be wise to try to silence compile warnings\nin these branches. The argument for this is basically that if we\ndon't, then every time someone builds one of these branches, they\nhave to tediously go through the warnings and verify that\nthey're not important. It won't take long for the accumulated\ntime-wastage from that to exceed the cost of back-patching whatever\nwe did to silence the warning in later branches.\n\nNow, I'm still not interested in trying to silence\nmaybe-uninitialized warnings pre-9.3, mainly because of the\nereport-ERROR-doesnt-return issue. (I saw far fewer of those\nunder gcc than clang, but not zero.) We could ignore those\nfiguring that 9.2 will be out of scope in a year anyway, or else\nteach 9.2's configure to select -Wno-maybe-uninitialized where\npossible.\n\nLikewise, getting check-world to parallelize successfully pre-v10\nseems like a bridge too far. But I would, for example, be in favor\nof back-patching eb9812f27 (Make pg_upgrade's test.sh less chatty).\nIt's just annoying to run check-world and get that output now.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sun, 05 Dec 2021 19:41:14 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Sun, Dec 5, 2021 at 7:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Based on these results, I think maybe we should raise our ambitions\n> a bit compared to Peter's original proposal. Specifically,\n> I wonder if it wouldn't be wise to try to silence compile warnings\n> in these branches. The argument for this is basically that if we\n> don't, then every time someone builds one of these branches, they\n> have to tediously go through the warnings and verify that\n> they're not important. It won't take long for the accumulated\n> time-wastage from that to exceed the cost of back-patching whatever\n> we did to silence the warning in later branches.\n\nYep. I have long been of the view, and have said before, that there is\nvery little harm in doing some maintenance of EOL branches. Making it\neasy to test against them is a great way to improve our chances of\nactually having the amount of backward-compatibility that we say we\nwant to have.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 6 Dec 2021 15:38:55 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> On Sun, Dec 5, 2021 at 7:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Based on these results, I think maybe we should raise our ambitions\n>> a bit compared to Peter's original proposal. Specifically,\n>> I wonder if it wouldn't be wise to try to silence compile warnings\n>> in these branches.\n\n> Yep. I have long been of the view, and have said before, that there is\n> very little harm in doing some maintenance of EOL branches. Making it\n> easy to test against them is a great way to improve our chances of\n> actually having the amount of backward-compatibility that we say we\n> want to have.\n\nRight. The question that's on the table is how much is the right\namount of maintenance. I think that back-patching user-visible bug\nfixes, for example, is taking things too far. What we want is to\nbe able to replicate the behavior of the branch's last released\nversion, using whatever build tools we are currently using. So\nback-patching something like that is counterproductive, because\nnow the behavior is not what was released.\n\nA minimal amount of maintenance would be \"only back-patch fixes\nfor issues that cause failure-to-build\". The next step up is \"fix\nissues that cause failure-to-pass-regression-tests\", and then above\nthat is \"fix developer-facing annoyances, such as compiler warnings\nor unwanted test output, as long as you aren't changing user-facing\nbehavior\". I now think that it'd be reasonable to include this\nlast group, although I'm pretty sure Peter didn't have that in mind\nin his policy sketch.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 06 Dec 2021 16:19:08 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Dec 6, 2021 at 4:19 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Right. The question that's on the table is how much is the right\n> amount of maintenance. I think that back-patching user-visible bug\n> fixes, for example, is taking things too far. What we want is to\n> be able to replicate the behavior of the branch's last released\n> version, using whatever build tools we are currently using. So\n> back-patching something like that is counterproductive, because\n> now the behavior is not what was released.\n>\n> A minimal amount of maintenance would be \"only back-patch fixes\n> for issues that cause failure-to-build\". The next step up is \"fix\n> issues that cause failure-to-pass-regression-tests\", and then above\n> that is \"fix developer-facing annoyances, such as compiler warnings\n> or unwanted test output, as long as you aren't changing user-facing\n> behavior\". I now think that it'd be reasonable to include this\n> last group, although I'm pretty sure Peter didn't have that in mind\n> in his policy sketch.\n\nYep, that seems reasonable to me.\n\nI guess the point about user-visible bug fixes is that, as soon as we\nstart doing that, we don't really want it to be hit-or-miss. We could\nmake a decision to back-patch all bug fixes or those of a certain\nseverity or whatever we like back to older branches, and then those\nbranches would be supported or semi-supported depending on what rule\nwe adopted, and we could even continue to do releases for them if we\nso chose. However, it wouldn't be a great idea to back-patch a\ncompletely arbitrary subset of our fixes into those branches, because\nthen it sort of gets confusing to understand what the status of that\nbranch is. I don't know that I'm terribly bothered by the idea that\nthe behavior of the branch might deviate from the last official\nrelease, because most bug fixes are pretty minor and wouldn't really\naffect testing much, but it would be a little annoying to explain to\nusers that those branches contain an arbitrary subset of newer fixes,\nand a little hard for us to understand what is and is not there.\n\nThat being said, suppose that a new compiler version comes out and on\nthat new compiler version, 'make check' crashes on the older branch\ndue to a missing WhateverGetDatum() call that we rectified in a later,\nback-patched commit. I would consider it reasonable to back-patch that\nparticular bug fix into an unsupported branch to make it testable,\njust like we would do for a failure-to-build issue.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 7 Dec 2021 11:33:38 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> I guess the point about user-visible bug fixes is that, as soon as we\n> start doing that, we don't really want it to be hit-or-miss. We could\n> make a decision to back-patch all bug fixes or those of a certain\n> severity or whatever we like back to older branches, and then those\n> branches would be supported or semi-supported depending on what rule\n> we adopted, and we could even continue to do releases for them if we\n> so chose. However, it wouldn't be a great idea to back-patch a\n> completely arbitrary subset of our fixes into those branches, because\n> then it sort of gets confusing to understand what the status of that\n> branch is.\n\nYup, and also confusing to understand whether a given new fix should\nbe back-patched into the out-of-support-but-keep-buildable branches.\nI want to settle on a reasonably well-defined policy for that.\n\nI'm basically suggesting that the policy should be \"back-patch the\nminimal fix needed so that you can still get a clean build and clean\ncheck-world run, using thus-and-such configure options\". (The point\nof the configure options limitation being to exclude moving-target\nexternal dependencies, such as Python.) I think that Peter's\noriginal suggestion could be read the same way except for the\nadjective \"clean\". He also said that only core regression needs\nto pass not check-world; but if we're trying to test things like\npg_dump compatibility, I think we want the wider scope of what to\nkeep working.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 07 Dec 2021 12:46:09 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\n\n> On Dec 7, 2021, at 8:33 AM, Robert Haas <robertmhaas@gmail.com> wrote:\n> \n> However, it wouldn't be a great idea to back-patch a\n> completely arbitrary subset of our fixes into those branches, because\n> then it sort of gets confusing to understand what the status of that\n> branch is. I don't know that I'm terribly bothered by the idea that\n> the behavior of the branch might deviate from the last official\n> release, because most bug fixes are pretty minor and wouldn't really\n> affect testing much, but it would be a little annoying to explain to\n> users that those branches contain an arbitrary subset of newer fixes,\n> and a little hard for us to understand what is and is not there.\n\nWouldn't you be able to see what changed by comparing the last released tag for version X.Y against the RELX_Y_STABLE branch? Something like `git diff REL8_4_22 origin/REL8_4_STABLE > buildability.patch`?\n\nHaving such a patch should make reproducing old corruption bugs easier, as you could apply the buildability.patch to the last branch that contained the bug. If anybody did that work, would we want it committed somewhere? REL8_4_19_BUILDABLE or such? For patches that apply trivially, that might not be worth keeping, but if the merge is difficult, maybe sharing with the community would make sense.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 7 Dec 2021 10:26:13 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Mark Dilger <mark.dilger@enterprisedb.com> writes:\n> Wouldn't you be able to see what changed by comparing the last released tag for version X.Y against the RELX_Y_STABLE branch? Something like `git diff REL8_4_22 origin/REL8_4_STABLE > buildability.patch`?\n\n> Having such a patch should make reproducing old corruption bugs easier, as you could apply the buildability.patch to the last branch that contained the bug. If anybody did that work, would we want it committed somewhere? REL8_4_19_BUILDABLE or such? For patches that apply trivially, that might not be worth keeping, but if the merge is difficult, maybe sharing with the community would make sense.\n\nI'm not entirely following ... are you suggesting that each released minor\nversion needs to be kept buildable separately? That seems like a huge\namount of extra committer effort with not much added value. If someone\ncomes to me and wants to investigate a bug in a branch that's already\nout-of-support, and they then say they're not running the last minor\nrelease, I'm going to tell them to come back after updating.\n\nIt is (I suspect) true that diffing the last release against branch\ntip would often yield a patch that could be used to make an older\nminor release buildable again. But when that patch doesn't work\ntrivially, I for one am not interested in making it work. And\nespecially not interested in doing so \"on spec\", with no certainty\nthat anyone would ever need it.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 07 Dec 2021 13:52:34 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\n\n> On Dec 7, 2021, at 10:52 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> \n> I'm not entirely following ... are you suggesting that each released minor\n> version needs to be kept buildable separately?\n\nNo. I'm just wondering if we want to share the product of such efforts if anybody (me, for instance) volunteers to do it for some subset of minor releases. For my heap corruption checking work, I might want to be able to build a small number of old minor releases that I know had corruption bugs.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 7 Dec 2021 10:59:02 -0800","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 12/7/21 13:59, Mark Dilger wrote:\n>> On Dec 7, 2021, at 10:52 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>>\n>> I'm not entirely following ... are you suggesting that each released minor\n>> version needs to be kept buildable separately?\n> No. I'm just wondering if we want to share the product of such efforts if anybody (me, for instance) volunteers to do it for some subset of minor releases. For my heap corruption checking work, I might want to be able to build a small number of old minor releases that I know had corruption bugs.\n>\n\nI doubt there's going to be a whole lot of changes. You should just be\nable to cherry-pick them in most cases I suspect.\n\n\ncheers\n\n\nandrew\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Tue, 7 Dec 2021 14:19:36 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On 06.12.21 22:19, Tom Lane wrote:\n> A minimal amount of maintenance would be \"only back-patch fixes\n> for issues that cause failure-to-build\". The next step up is \"fix\n> issues that cause failure-to-pass-regression-tests\", and then above\n> that is \"fix developer-facing annoyances, such as compiler warnings\n> or unwanted test output, as long as you aren't changing user-facing\n> behavior\". I now think that it'd be reasonable to include this\n> last group, although I'm pretty sure Peter didn't have that in mind\n> in his policy sketch.\n\nI would be okay with that.\n\n\n","msg_date":"Thu, 9 Dec 2021 15:01:43 +0100","msg_from":"Peter Eisentraut <peter.eisentraut@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"[ mostly for the archives' sake ]\n\nI wrote:\n> I ran a new set of experiments concerning building back branches\n> on modern platforms, this time trying Fedora 35 (gcc 11.2.1)\n> on x86_64. I widened the scope of the testing a bit by adding\n> \"--enable-nls --with-perl\" and running check-world not just the\n> core tests. Salient results:\n\n> * 9.1 fails with \"conflicting types for 'base_yylex'\", much as\n> I saw on macOS except it's a hard error on this compiler.\n\nI poked a little harder at what might be needed to get 9.1 compiled\non modern platforms. It looks like the base_yylex issue is down\nto newer versions of flex doing things differently. We fixed\nthat in the v10 era via 72b1e3a21 (Build backend/parser/scan.l and\ninterfaces/ecpg/preproc/pgc.l standalone) and 92fb64983 (Use \"%option\nprefix\" to set API names in ecpg's lexer), which were later back-patched\nas far down as 9.2. It might not be out of the question to back-patch\nthose further, but the 9.2 patches don't apply cleanly to 9.1, so some\neffort would be needed.\n\nWorrisomely, I also noted warnings like\n\nparse_coerce.c:791:67: warning: array subscript 1 is above array bounds of 'Oid[1]' {aka 'unsigned int[1]'} [-Warray-bounds]\n 791 | Assert(nargs < 2 || procstruct->proargtypes.values[1] == INT4OID);\n | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~\n\nwhich remind me that 9.1 lacks 8137f2c32 (Hide most variable-length fields\nfrom Form_pg_* structs). We did stick -fno-aggressive-loop-optimizations\ninto 9.1 and older branches back in 2015, but I don't have a lot of\nconfidence that that'd be sufficient to prevent misoptimizations in\ncurrent-vintage compilers. Back-patching 8137f2c32 and all the follow-on\nwork is very clearly not something to consider, so dialing down the -O\nlevel might be necessary if you were interested in making this go.\n\nIn short then, there is a really large gap between 9.1 and 9.2 in terms\nof how hard they are to build on current toolchains. It's kind of\nfortunate that Peter proposed 9.2 rather than some earlier cutoff.\nIn any case, I've completely lost interest in trying to move the\nkeep-it-buildable cutoff to any earlier than 9.2; it doesn't look\nlike the effort-to-benefit ratio would be attractive at all.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 09 Dec 2021 12:50:40 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"\nOn 12/9/21 12:50, Tom Lane wrote:\n>\n> In short then, there is a really large gap between 9.1 and 9.2 in terms\n> of how hard they are to build on current toolchains. It's kind of\n> fortunate that Peter proposed 9.2 rather than some earlier cutoff.\n> In any case, I've completely lost interest in trying to move the\n> keep-it-buildable cutoff to any earlier than 9.2; it doesn't look\n> like the effort-to-benefit ratio would be attractive at all.\n>\n> \t\t\t\n\n\n9.2 is how far back crake goes in testing pg_ugrade from old versions,\nso that could well be a convenient stopping point. For older versions\nthere is still the possibility of building on older toolchains and\nrunning on modern ones. Yes it's more cumbersome, but it does mean we\ncan test an awful long way back. I don't remember the last time I saw a\nreally old version in the wild, but I'm sure there are some out there\nsitting in a cupboard humming along.\n\nThis might also be a good time to revive work on making the TAP test\nframework backwards compatible via subclassing.\n\n\ncheers\n\n\nandrew\n\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Sat, 11 Dec 2021 10:17:17 -0500","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Andrew Dunstan <andrew@dunslane.net> writes:\n> 9.2 is how far back crake goes in testing pg_ugrade from old versions,\n> so that could well be a convenient stopping point. For older versions\n> there is still the possibility of building on older toolchains and\n> running on modern ones. Yes it's more cumbersome, but it does mean we\n> can test an awful long way back.\n\nRight. I think the point of the current discussion is to ensure that,\nif we expect new patches for pg_dump or psql to work against version-N\nservers, that it's not too unpleasant for patch submitters to build\nand test against version N. There's a different discussion to be had\nabout what we do if we receive a bug report about compatibility with\nsome more-ancient-than-that version. But that is, I hope, a far less\ncommon scenario; so it's okay if it requires extra effort, and/or use\nof setups that not everyone has handy.\n\nAnyway, it seems like there's some consensus that 9.2 is a good\nstopping place for today. I'll push forward with\n(1) back-patching as necessary to make 9.2 and up build cleanly\non the platforms I have handy;\n(2) ripping out pg_dump's support for pre-9.2 servers;\n(3) ripping out psql's support for pre-9.2 servers.\n\nIn a preliminary look, it did not seem that (3) would save very\nmuch code, but it seems like we ought to do it if we're being\nconsistent.\n\nA point we've not discussed is whether to drop any bits of libpq\nthat are only needed for such old servers. I feel a bit more\nuncomfortable about that, mainly because I'm pretty sure that\nonly a few lines of code would be involved, and it seems to have\nmore of an air of burning-the-bridges finality about it than (say)\ndropping psql/describe.c support. On the other hand, the point\nabout what's required to test future patches still applies.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Sun, 12 Dec 2021 01:24:24 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"I wrote:\n> Anyway, it seems like there's some consensus that 9.2 is a good\n> stopping place for today. I'll push forward with\n> (1) back-patching as necessary to make 9.2 and up build cleanly\n> on the platforms I have handy;\n\nI've done as much as I plan to do in that direction. As of the\nrespective branch tips, I see clean builds and check-world\nresults with minimal configure options in all branches back to 9.2\non Fedora 35 (gcc 11.2.1) and macOS Monterey (Apple clang 13.0.0).\n\nA few notes for the archives' sake:\n\n* As discussed, parallel check-world is unreliable before v10;\nperhaps this is worth improving, but I doubt it. I did find\nthat aggressive parallelism in the build process is fine.\n\n* On some compilers, pre-v10 branches produce this warning:\n\nscan.c: In function 'yy_try_NUL_trans':\nscan.c:10189:23: warning: unused variable 'yyg' [-Wunused-variable]\n struct yyguts_t * yyg = (struct yyguts_t*)yyscanner; /* This var may be unused depending upon options. */\n\nIn principle we could back-patch 65d508fd4 to silence that,\nbut I think that fix is more invasive than what we want to\ndo in these branches. We lived with that warning for years\nbefore figuring out how to get rid of it, so I think we can\ncontinue to accept it in these branches.\n\n* 9.2's plperl fails to compile on macOS:\n\n./plperl.h:53:10: fatal error: 'EXTERN.h' file not found\n#include \"EXTERN.h\"\n\nThis is evidently because 9.2 predates the \"sysroot\" hacking\nwe did later (5e2217131 and many many subsequent tweaks).\nI judge this not worth the trouble to fix, because the argument\nfor supporting --with-perl in these branches is basically that\nwe need a PL with transforms to test pg_dump ... but transforms\ndidn't come in until 9.5. (Reviewing the commit log, I suppose\nthat 9.3 and 9.4 would also fail to build in some macOS\nconfigurations, but by the same argument I see no need to work\nfurther on those branches either. 9.5 does have all the\nsysroot changes I can find in the log.)\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 13 Dec 2021 12:23:10 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Mon, Dec 13, 2021 at 12:23 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> I've done as much as I plan to do in that direction. As of the\n> respective branch tips, I see clean builds and check-world\n> results with minimal configure options in all branches back to 9.2\n> on Fedora 35 (gcc 11.2.1) and macOS Monterey (Apple clang 13.0.0).\n\nI think this is great. Thanks for being willing to work on it.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 13 Dec 2021 12:33:50 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"I wrote:\n> Anyway, it seems like there's some consensus that 9.2 is a good\n> stopping place for today. I'll push forward with\n> (1) back-patching as necessary to make 9.2 and up build cleanly\n> on the platforms I have handy;\n> (2) ripping out pg_dump's support for pre-9.2 servers;\n> (3) ripping out psql's support for pre-9.2 servers.\n\nI've completed the pg_dump/pg_dumpall part of that, but while\nupdating the docs I started to wonder whether we shouldn't nuke\npg_dump's --no-synchronized-snapshots option. As far as I can\nmake out, the remaining use case for that is to let you perform an\nunsafe parallel dump from a standby server of an out-of-support\nmajor version. I'm not very clear why we allowed that at all,\never, rather than saying you can't parallelize in such cases.\nBut for sure that remaining use case is paper thin, and leaving\nthe option available seems way more likely to let people shoot\nthemselves in the foot than to let them do anything helpful.\n\nBarring objections, I'll remove that option in a day or two.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 14 Dec 2021 17:18:44 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Tue, Dec 14, 2021 at 05:18:44PM -0500, Tom Lane wrote:\n> I wrote:\n> > Anyway, it seems like there's some consensus that 9.2 is a good\n> > stopping place for today. I'll push forward with\n> > (1) back-patching as necessary to make 9.2 and up build cleanly\n> > on the platforms I have handy;\n> > (2) ripping out pg_dump's support for pre-9.2 servers;\n> > (3) ripping out psql's support for pre-9.2 servers.\n> \n> I've completed the pg_dump/pg_dumpall part of that, but while\n\nIs it possible to clean up pg_upgrade, too ?\n\n-- \nJustin\n\n\n","msg_date":"Wed, 15 Dec 2021 22:08:07 -0600","msg_from":"Justin Pryzby <pryzby@telsasoft.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Justin Pryzby <pryzby@telsasoft.com> writes:\n> On Tue, Dec 14, 2021 at 05:18:44PM -0500, Tom Lane wrote:\n>> I've completed the pg_dump/pg_dumpall part of that, but while\n\n> Is it possible to clean up pg_upgrade, too ?\n\nhttps://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=e469f0aaf3c586c8390bd65923f97d4b1683cd9f\n\nI'm still working on psql.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 15 Dec 2021 23:55:41 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Wed, Dec 15, 2021 at 10:08:07PM -0600, Justin Pryzby wrote:\n> Is it possible to clean up pg_upgrade, too ?\n\nNevermind - I found yesterday's e469f0aaf3 after git-fetch.\n\nI think you missed a few parts though ?\n\nsrc/bin/pg_upgrade/function.c\n if (GET_MAJOR_VERSION(old_cluster.major_version) <= 900)\n...\n if (GET_MAJOR_VERSION(old_cluster.major_version) <= 900 &&\n strcmp(lib, \"$libdir/plpython\") == 0)\n\nsrc/bin/pg_upgrade/option.c\n * Someday, the port number option could be removed and passed\n * using -o/-O, but that requires postmaster -C to be\n * supported on all old/new versions (added in PG 9.2).\n...\n if (GET_MAJOR_VERSION(cluster->major_version) >= 901)\n\n\n","msg_date":"Wed, 15 Dec 2021 22:58:04 -0600","msg_from":"Justin Pryzby <pryzby@telsasoft.com>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"Justin Pryzby <pryzby@telsasoft.com> writes:\n> I think you missed a few parts though ?\n\nUm. I think those are leftover from when I was intending the\ncutoff to be 9.0 not 9.2. I'll take a fresh look tomorrow.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 16 Dec 2021 00:02:54 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":true,"msg_subject":"Re: pg_dump versus ancient server versions"},{"msg_contents":"On Fri, 22 Oct 2021 at 19:27, Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> Another thing to think about in that regard: how likely is that\n> PostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\n> operating system? I suspect the answer is \"not very.\" I seem to recall\n> Greg Stark trying to compile really old versions of PostgreSQL for a\n> conference talk some years ago, and he got back to a point where it\n> just became impossible to make work on modern toolchains even with a\n> decent amount of hackery.\n\nThat was when I compared sorting performance over time. I was able to\nget Postgres to build back to the point where 64-bit architecture\nsupport was added. From Andrew Dunstans comment later in this thread\nI'm guessing that was 7.2\n\nThat was basically at the point where 64-bit architecture support was\nadded. It looks like the earliest date on the graphs in the talk are\n2002-11-27 which matches the 7.3 release date. I think building\nearlier versions would have been doable if I had built them in 32-bit\nmode.\n\n-- \ngreg\n\n\n","msg_date":"Fri, 17 Dec 2021 03:06:50 -0500","msg_from":"Greg Stark <stark@mit.edu>","msg_from_op":false,"msg_subject":"Re: pg_dump versus ancient server versions"}],"string":"[\n {\n \"msg_contents\": \"While doing some desultory testing, I realized that the commit\\nI just pushed (92316a458) broke pg_dump against 8.0 servers:\\n\\n$ pg_dump -p5480 -s regression\\npg_dump: error: schema with OID 11 does not exist\\n\\nThe reason turns out to be something I'd long forgotten about: except\\nfor the few \\\"bootstrap\\\" catalogs, our system catalogs didn't use to\\nhave fixed OIDs. That changed at 7c13781ee, but 8.0 predates that.\\nSo when pg_dump reads a catalog on 8.0, it gets some weird number for\\n\\\"tableoid\\\", and the logic I just put into common.c's findNamespaceByOid\\net al fails to find the resulting DumpableObjects.\\n\\nSo my first thought was just to revert 92316a458 and give up on it as\\na bad idea. However ... does anyone actually still care about being\\nable to dump from such ancient servers? In addition to this issue,\\nI'm thinking of the discussion at [1] about wanting to use unnest()\\nin pg_dump, and of what we would need to do instead in pre-8.4 servers\\nthat lack that. Maybe it'd be better to move up pg_dump's minimum\\nsupported server version to 8.4 or 9.0, and along the way whack a\\nfew more lines of its backward-compatibility hacks. If there is\\nanyone out there still using an 8.x server, they could use its\\nown pg_dump whenever they get around to migration.\\n\\nAnother idea would be to ignore \\\"tableoid\\\" and instead use the OIDs\\nwe're expecting, but that's way too ugly for my taste, especially\\ngiven the rather thin argument for committing 92316a458 at all.\\n\\nAnyway, I think the default answer is \\\"revert 92316a458 and keep the\\ncompatibility goalposts where they are\\\". But I wanted to open up a\\ndiscussion to see if anyone likes the other approach better.\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 18:38:33 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n\\n> Anyway, I think the default answer is \\\"revert 92316a458 and keep the\\n> compatibility goalposts where they are\\\". But I wanted to open up a\\n> discussion to see if anyone likes the other approach better.\\n>\\n> [1]\\n> https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.de\\n>\\n>\\nI'd rather drop legacy support than revert. Even if the benefit of\\n92316a456 of is limited to refactoring the fact it was committed is enough\\nfor me to feel it is a worthwhile improvement. It's still yet another five\\nyears before there won't be a supported release that can dump/restore this\\n- so 20 years for someone to have upgraded without having to go to the (not\\nthat big a) hassle of installing an out-of-support version as a stop-over.\\n\\nIn short, IMO, the bar for this kind of situation should be 10 releases at\\nmost - 5 of which would be in support at the time the patch goes in. We\\ndon't have to actively drop support of older stuff but anything older\\nshouldn't be preventing new commits.\\n\\nDavid J.\\n\\nOn Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:Anyway, I think the default answer is \\\"revert 92316a458 and keep the\\ncompatibility goalposts where they are\\\". But I wanted to open up a\\ndiscussion to see if anyone likes the other approach better.\\n[1] https://www.postgresql.org/message-id/20211022055939.z6fihsm7hdzbjttf%40alap3.anarazel.deI'd rather drop legacy support than revert. Even if the benefit of 92316a456 of is limited to refactoring the fact it was committed is enough for me to feel it is a worthwhile improvement. It's still yet another five years before there won't be a supported release that can dump/restore this - so 20 years for someone to have upgraded without having to go to the (not that big a) hassle of installing an out-of-support version as a stop-over.In short, IMO, the bar for this kind of situation should be 10 releases at most - 5 of which would be in support at the time the patch goes in. We don't have to actively drop support of older stuff but anything older shouldn't be preventing new commits.David J.\",\n \"msg_date\": \"Fri, 22 Oct 2021 16:00:19 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 6:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> So my first thought was just to revert 92316a458 and give up on it as\\n> a bad idea. However ... does anyone actually still care about being\\n> able to dump from such ancient servers?\\n\\nI think I recently heard about an 8.4 server still out there in the\\nwild, but AFAICR it's been a long time since I've heard about anything\\nolder.\\n\\nIt seems to me that if you're upgrading by a dozen server versions in\\none shot, it's not a totally crazy idea that you might want to do it\\nin steps, or use the pg_dump for the version you have and then hack\\nthe dump. I kind of wonder if there's really any hope of a pain-free\\nupgrade across that many versions anyway. There are things that can\\nbite you despite all the work we've put into pg_dump, like having\\nobjects that depend on system objects whose definition has changed\\nover the years, plus implicit casting differences, operator precedence\\nchanges, => getting deprecated, lots of GUC changes, etc. You are\\ngoing to be able to upgrade in the end, but it's probably going to\\ntake some work. So I'm not really sure that giving up pg_dump\\ncompatibility for versions that old is losing as much as it may seem.\\n\\nAnother thing to think about in that regard: how likely is that\\nPostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\\noperating system? I suspect the answer is \\\"not very.\\\" I seem to recall\\nGreg Stark trying to compile really old versions of PostgreSQL for a\\nconference talk some years ago, and he got back to a point where it\\njust became impossible to make work on modern toolchains even with a\\ndecent amount of hackery. One tends to think of C as about as static a\\nthing as can be, but that's kind of missing the point. On my laptop\\nfor example, my usual configure invocation fails on 7.4 with:\\n\\nchecking for SSL_library_init in -lssl... no\\nconfigure: error: library 'ssl' is required for OpenSSL\\n\\nIn fact, I get that same failure on every branch older than 9.2. I\\nexpect I could work around that by disabling SSL or finding an older\\nversion of OpenSSL that works the way those branches expect, but that\\nmight not be the only problem, either. Now I understand you could\\nhave PostgreSQL 15 on a new box and PostgreSQL 7.x on an ancient one\\nand connect via the network, and it would in all fairness be cool if\\nthat Just Worked. But I suspect that even if that did happen in the\\nlab, reality wouldn't often be so kind.\\n\\n--\\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 19:26:57 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com> writes:\\n> On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Anyway, I think the default answer is \\\"revert 92316a458 and keep the\\n>> compatibility goalposts where they are\\\". But I wanted to open up a\\n>> discussion to see if anyone likes the other approach better.\\n\\n> ... IMO, the bar for this kind of situation should be 10 releases at\\n> most - 5 of which would be in support at the time the patch goes in. We\\n> don't have to actively drop support of older stuff but anything older\\n> shouldn't be preventing new commits.\\n\\nYeah. I checked into when it was that we dropped pre-8.0 support\\nfrom pg_dump, and the answer is just about five years ago (64f3524e2).\\nSo moving the bar forward by five releases isn't at all out of line.\\n8.4 would be eight years past EOL by the time v15 comes out.\\n\\nOne of the arguments for the previous change was that it was getting\\nvery hard to build old releases on modern platforms, thus making it\\nhard to do any compatibility testing. I believe the same is starting\\nto become true of the 8.x releases, though I've not tried personally\\nto build any of them in some time. (The executables I'm using for\\nthem date from 2014 or earlier, and have not been recompiled in\\nsubsequent platform upgrades ...) Anyway it's definitely not free\\nto continue to support old source server versions.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 19:30:25 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> Another thing to think about in that regard: how likely is that\\n> PostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\\n> operating system? I suspect the answer is \\\"not very.\\\" I seem to recall\\n> Greg Stark trying to compile really old versions of PostgreSQL for a\\n> conference talk some years ago, and he got back to a point where it\\n> just became impossible to make work on modern toolchains even with a\\n> decent amount of hackery.\\n\\nRight. The toolchains keep moving, even if the official language\\ndefinition doesn't. For grins, I just checked out REL8_4_STABLE\\non my M1 Mac, and found that it only gets this far:\\n\\nchecking test program... ok\\nchecking whether long int is 64 bits... no\\nchecking whether long long int is 64 bits... no\\nconfigure: error: Cannot find a working 64-bit integer type.\\n\\nwhich turns out to be down to a configure-script issue we fixed\\nsome years ago, ie using exit() without a prototype:\\n\\nconftest.c:158:3: error: implicitly declaring library function 'exit' with type\\\\\\n 'void (int) __attribute__((noreturn))' [-Werror,-Wimplicit-function-declaratio\\\\\\nn]\\n exit(! does_int64_work());\\n ^\\n\\nI notice that the configure script is also selecting some warning\\nswitches that this compiler doesn't much like, plus it doesn't\\nbelieve 2.6.x flex is usable. So that's *at least* three things\\nthat'd have to be hacked even to get to a successful configure run.\\n\\nIndividually such issues are (usually) not very painful, but when\\nyou have to recreate all of them at once it's a daunting project.\\n\\nSo if I had to rebuild 8.4 from scratch right now, I would not be\\na happy camper. That seems like a good argument for not deeming\\nit to be something we still have to support.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 19:48:13 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-22, Robert Haas wrote:\\n\\n> In fact, I get that same failure on every branch older than 9.2. I\\n> expect I could work around that by disabling SSL or finding an older\\n> version of OpenSSL that works the way those branches expect, but that\\n> might not be the only problem, either.\\n\\nI just tried to build 9.1. My config line there doesn't have ssl, but I\\ndo get this in the compile stage:\\n\\ngram.c:69:25: error: conflicting types for ‘base_yylex’\\n 69 | #define yylex base_yylex\\n | ^~~~~~~~~~\\nscan.c:15241:12: note: in expansion of macro ‘yylex’\\n15241 | extern int yylex \\\\\\n | ^~~~~\\nIn file included from /pgsql/source/REL9_1_STABLE/src/backend/parser/gram.y:60:\\n/pgsql/source/REL9_1_STABLE/src/include/parser/gramparse.h:66:12: note: previous declaration of ‘base_yylex’ was here\\n 66 | extern int base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp,\\n | ^~~~~~~~~~\\ngram.c:69:25: error: conflicting types for ‘base_yylex’\\n 69 | #define yylex base_yylex\\n | ^~~~~~~~~~\\nscan.c:15244:21: note: in expansion of macro ‘yylex’\\n15244 | #define YY_DECL int yylex \\\\\\n | ^~~~~\\nscan.c:15265:1: note: in expansion of macro ‘YY_DECL’\\n15265 | YY_DECL\\n | ^~~~~~~\\nIn file included from /pgsql/source/REL9_1_STABLE/src/backend/parser/gram.y:60:\\n/pgsql/source/REL9_1_STABLE/src/include/parser/gramparse.h:66:12: note: previous declaration of ‘base_yylex’ was here\\n 66 | extern int base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp,\\n | ^~~~~~~~~~\\nmake[3]: *** [../../../src/Makefile.global:655: gram.o] Error 1\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\\"El Maquinismo fue proscrito so pena de cosquilleo hasta la muerte\\\"\\n(Ijon Tichy en Viajes, Stanislaw Lem)\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Oct 2021 20:51:22 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, Oct 22, 2021 at 7:51 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:\\n> I just tried to build 9.1. My config line there doesn't have ssl, but I\\n> do get this in the compile stage:\\n\\nHmm.\\n\\nYou know, one thing we could think about doing is patching some of the\\nolder branches to make them compile on modern machines. That would not\\nonly be potentially useful for people who are upgrading from ancient\\nversions, but also for hackers trying to do research on the origin of\\nbugs or performance problems, and also for people who are trying to\\nmaintain some kind of backward compatibility or other and want to test\\nagainst old versions.\\n\\nI don't know whether that's really worth the effort and I expect Tom\\nwill say that it's not. If he does say that, he may be right. But I\\nthink if I were trying to extract my data from an old 7.4 database, I\\nthink I'd find it a lot more useful if I could make 9.0 or 9.2 or\\nsomething compile and talk to it than if I had to use v15 and hope\\nthat held together somehow. It doesn't really make sense to try to\\nkeep compatibility of any sort with versions we can no longer test\\nagainst.\\n\\n--\\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 16:45:20 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> You know, one thing we could think about doing is patching some of the\\n> older branches to make them compile on modern machines. That would not\\n> only be potentially useful for people who are upgrading from ancient\\n> versions, but also for hackers trying to do research on the origin of\\n> bugs or performance problems, and also for people who are trying to\\n> maintain some kind of backward compatibility or other and want to test\\n> against old versions.\\n\\nYeah. We have done that in the past; I thought more than once,\\nbut right now the only case I can find is d13f41d21/105f3ef49.\\nThere are some other post-EOL commits in git, but I think the\\nothers were mistakes from over-enthusiastic back-patching, while\\nthat one was definitely an intentional portability fix for EOL'd\\nversions.\\n\\n> I don't know whether that's really worth the effort and I expect Tom\\n> will say that it's not. If he does say ,that, he may be right.\\n\\nHmm ... I guess the question is how much work we feel like putting\\ninto that, and how we'd track whether old branches still work,\\nand on what platforms. It could easily turn into a time sink\\nthat's not justified by the value. I do see your point that there's\\nsome value in it; I'm just not sure about the cost/benefit ratio.\\n\\nOne thing we could do that would help circumscribe the costs is to say\\n\\\"we are not going to consider issues involving new compiler warnings\\nor bugs caused by more-aggressive optimization\\\". We could mechanize\\nthat pretty effectively by changing configure shortly after a branch's\\nEOL to select -O0 and no extra warning flags, so that anyone building\\nfrom branch tip would get those switch choices.\\n\\n(I have no idea what this might look like on the Windows side, but\\nI'm concerned by the fact that we seem to need fixes every time a\\nnew Visual Studio major version comes out.)\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 17:46:17 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-24, Robert Haas wrote:\\n\\n> You know, one thing we could think about doing is patching some of the\\n> older branches to make them compile on modern machines. That would not\\n> only be potentially useful for people who are upgrading from ancient\\n> versions, but also for hackers trying to do research on the origin of\\n> bugs or performance problems, and also for people who are trying to\\n> maintain some kind of backward compatibility or other and want to test\\n> against old versions.\\n\\nI think it is worth *some* effort, at least as far back as we want to\\nclaim that we maintain pg_dump and/or psql compatibility, assuming it is\\nnot too onerous. For instance, I wouldn't want to clutter buildfarm or\\nCI dashboards with testing these branches, unless it is well isolated\\nfrom regular ones; we shouldn't commit anything that's too invasive; and\\nwe shouldn't make any claims about supportability of these abandoned\\nbranches.\\n\\nAs an example, I did backpatch one such fix to 8.3 (just over a year)\\nand 8.2 (four years) after they had closed -- see d13f41d21538 and\\n105f3ef492ab.\\n\\n-- \\nÁlvaro Herrera 39°49'30\\\"S 73°17'W — https://www.EnterpriseDB.com/\\n\\\"Puedes vivir sólo una vez, pero si lo haces bien, una vez es suficiente\\\"\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 18:52:00 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, 2021-10-22 at 19:26 -0400, Robert Haas wrote:\\n> On Fri, Oct 22, 2021 at 6:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> > So my first thought was just to revert 92316a458 and give up on it as\\n> > a bad idea. However ... does anyone actually still care about being\\n> > able to dump from such ancient servers?\\n> \\n> I think I recently heard about an 8.4 server still out there in the\\n> wild, but AFAICR it's been a long time since I've heard about anything\\n> older.\\n\\nI had a customer with 8.3 in the not too distant past, but that need not\\nstop the show. If necessary, they can dump with 8.3 and restire that.\\n\\nYours,\\nLaurenz Albe\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:29:19 +0200\",\n \"msg_from\": \"Laurenz Albe <laurenz.albe@cybertec.at>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/22/21 19:30, Tom Lane wrote:\\n> \\\"David G. Johnston\\\" <david.g.johnston@gmail.com> writes:\\n>> On Fri, Oct 22, 2021 at 3:42 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>>> Anyway, I think the default answer is \\\"revert 92316a458 and keep the\\n>>> compatibility goalposts where they are\\\". But I wanted to open up a\\n>>> discussion to see if anyone likes the other approach better.\\n>> ... IMO, the bar for this kind of situation should be 10 releases at\\n>> most - 5 of which would be in support at the time the patch goes in. We\\n>> don't have to actively drop support of older stuff but anything older\\n>> shouldn't be preventing new commits.\\n> Yeah. I checked into when it was that we dropped pre-8.0 support\\n> from pg_dump, and the answer is just about five years ago (64f3524e2).\\n> So moving the bar forward by five releases isn't at all out of line.\\n> 8.4 would be eight years past EOL by the time v15 comes out.\\n>\\n> One of the arguments for the previous change was that it was getting\\n> very hard to build old releases on modern platforms, thus making it\\n> hard to do any compatibility testing. I believe the same is starting\\n> to become true of the 8.x releases, though I've not tried personally\\n> to build any of them in some time. (The executables I'm using for\\n> them date from 2014 or earlier, and have not been recompiled in\\n> subsequent platform upgrades ...) Anyway it's definitely not free\\n> to continue to support old source server versions.\\n\\n\\nBut we don't need to build them on modern platforms, just run them on\\nmodern platforms, ISTM.\\n\\nSome months ago I built binaries all the way back to 7.2 that with a\\nlittle help run on modern Fedora and Ubuntu systems. I just upgraded my\\nFedora system from 31 to 34 and they still run. See\\n<https://gitlab.com/adunstan/pg-old-bin> One of the intended use cases\\nwas to test pg_dump against old versions.\\n\\nI'm not opposed to us cutting off support for very old versions,\\nalthough I think we should only do that very occasionally (no more than\\nonce every five years, say) unless there's a very good reason. I'm also\\nnot opposed to us making small adjustments to allow us to build old\\nversions on modern platforms, but if we do that then we should probably\\nhave some buildfarm support for it.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 08:29:24 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 5:46 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Hmm ... I guess the question is how much work we feel like putting\\n> into that, and how we'd track whether old branches still work,\\n> and on what platforms. It could easily turn into a time sink\\n> that's not justified by the value. I do see your point that there's\\n> some value in it; I'm just not sure about the cost/benefit ratio.\\n\\nRight. Well, we could leave it up to people who care to decide how\\nmuch work they want to do, perhaps. But I do find it annoying that\\npg_dump is supposed to maintain compatibility with server releases\\nthat I can't easily build. Fortunately I don't patch pg_dump very\\noften, but if I did, it'd be very difficult for me to verify that\\nthings work against really old versions. I know that you (Tom) do a\\nlot of work of this type though. In my opinion, if you find yourself\\nworking on a project of this type and as part of that you do some\\nfixes to an older branch to make it compile, maybe you ought to commit\\nthose so that the next person doesn't have the same problem. And maybe\\nwhen we add support for newer versions of OpenSSL or Windows, we ought\\nto consider back-patching those even to unsupported releases if\\nsomeone's willing to do the work. If they're not, they're not, but I\\nthink we tend to strongly discourage commits to EOL branches, and I\\nthink maybe we should stop doing that. Not that people should\\nroutinely back-patch bug fixes, but stuff that makes it easier to\\nbuild seems fair game.\\n\\nI don't think we need to worry too much about users getting the wrong\\nimpression. People who want to know what is supported are going to\\nlook at our web site for that information, and they are going to look\\nfor releases. I can't rule out the possibility that someone is going\\nto build an updated version of 7.4 or 8.2 with whatever patches we\\nmight choose to commit there, but they're unlikely to think that means\\nthose are fully supported branches. And if they somehow do think that\\ndespite all evidence to the contrary, we can just tell them that they\\nare mistaken.\\n\\n> One thing we could do that would help circumscribe the costs is to say\\n> \\\"we are not going to consider issues involving new compiler warnings\\n> or bugs caused by more-aggressive optimization\\\". We could mechanize\\n> that pretty effectively by changing configure shortly after a branch's\\n> EOL to select -O0 and no extra warning flags, so that anyone building\\n> from branch tip would get those switch choices.\\n\\nI don't much like the idea of including -O0 because it seems like it\\ncould be confusing. People might not realize that that the build\\nsettings have been changed. I don't think that's really the problem\\nanyway: anybody who hits compiler warnings in older branches could\\ndecide to fix them (and as long as it's a committer who will be\\nresponsible for their own work, I think that's totally fine) or enable\\n-O0 locally. I routinely do that when I hit problems on older\\nbranches, and it helps a lot, but the way I see it, that's such an\\neasy change that there's little reason to make it in the source code.\\nWhat's a lot more annoying is if the compile fails altogether, or you\\ncan't even get past the configure step.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 08:55:37 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 8:29 AM Andrew Dunstan <andrew@dunslane.net> wrote:\\n> But we don't need to build them on modern platforms, just run them on\\n> modern platforms, ISTM.\\n\\nI don't really agree with this.\\n\\n> Some months ago I built binaries all the way back to 7.2 that with a\\n> little help run on modern Fedora and Ubuntu systems. I just upgraded my\\n> Fedora system from 31 to 34 and they still run. See\\n> <https://gitlab.com/adunstan/pg-old-bin> One of the intended use cases\\n> was to test pg_dump against old versions.\\n\\nThat's cool, but I don't have a Fedora or Ubuntu VM handy, and it does\\nseem like if people are working on testing against old versions, they\\nmight even want to be able to recompile with debugging statements\\nadded or something. So I think actually compiling is a lot better than\\nbeing able to get working binaries from someplace, even though the\\nlatter is better than nothing.\\n\\n> I'm not opposed to us cutting off support for very old versions,\\n> although I think we should only do that very occasionally (no more than\\n> once every five years, say) unless there's a very good reason. I'm also\\n> not opposed to us making small adjustments to allow us to build old\\n> versions on modern platforms, but if we do that then we should probably\\n> have some buildfarm support for it.\\n\\nYeah, I think having a small number of buildfarm animals testing very\\nold versions would be nice. Perhaps we can call them tyrannosaurus,\\nbrontosaurus, triceratops, etc. :-)\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 08:59:56 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> Right. Well, we could leave it up to people who care to decide how\\n> much work they want to do, perhaps. But I do find it annoying that\\n> pg_dump is supposed to maintain compatibility with server releases\\n> that I can't easily build. Fortunately I don't patch pg_dump very\\n> often, but if I did, it'd be very difficult for me to verify that\\n> things work against really old versions. I know that you (Tom) do a\\n> lot of work of this type though. In my opinion, if you find yourself\\n> working on a project of this type and as part of that you do some\\n> fixes to an older branch to make it compile, maybe you ought to commit\\n> those so that the next person doesn't have the same problem.\\n\\nWell, the answer to that so far is that I've never done such fixes.\\nI have the last released versions of old branches laying around,\\nand that's what I test against. It's been sufficient so far, although\\nif I suddenly needed to do (say) SSL-enabled testing, that would be\\na problem because I don't think I built with SSL for any of those\\nbranches.\\n\\nBecause of that angle, I concur with your position that it'd really\\nbe desirable to be able to build old versions on modern platforms.\\nEven if you've got an old executable, it might be misconfigured for\\nthe purpose you have in mind.\\n\\n> And maybe\\n> when we add support for newer versions of OpenSSL or Windows, we ought\\n> to consider back-patching those even to unsupported releases if\\n> someone's willing to do the work. If they're not, they're not, but I\\n> think we tend to strongly discourage commits to EOL branches, and I\\n> think maybe we should stop doing that. Not that people should\\n> routinely back-patch bug fixes, but stuff that makes it easier to\\n> build seems fair game.\\n\\nWhat concerns me here is that we not get into a position where we're\\neffectively still maintaining EOL'd versions. Looking at the git\\nhistory yesterday reminded me that we had such a situation back in\\nthe early 7.x days. I can see that I still occasionally made commits\\ninto 7.1 and 7.2 years after the last releases of those branches,\\nwhich ended up being a complete waste of effort. There was no policy\\nguiding what to back-patch into what branches, partly because we\\ndidn't have a defined EOL policy then. So I want to have a policy\\n(and a pretty tight one) before I'll go back to doing that.\\n\\nRoughly speaking, I think the policy should be \\\"no feature bug fixes,\\nnot even security fixes, for EOL'd branches; only fixes that are\\nminimally necessary to make it build on newer platforms\\\". And\\nI want to have a sunset provision even for that. Fixing every branch\\nforevermore doesn't scale.\\n\\nThere's also the question of how we get to a working state in the\\nfirst place -- as we found upthread, there's a fair-sized amount\\nof work to do just to restore buildability right now, for anything\\nthat was EOL'd more than a year or two back. I'm not volunteering\\nfor that, but somebody would have to to get things off the ground.\\n\\nAlso, I concur with Andrew's point that we'd really have to have\\nbuildfarm support. However, this might not be as bad as it seems.\\nIn principle we might just need to add resurrected branches back to\\nthe branches_to_build list. Given my view of what the back-patching\\npolicy ought to be, a new build in an old branch might only be\\nrequired a couple of times a year, which would not be an undue\\ninvestment of buildfarm resources. (Hmmm ... but disk space could\\nbecome a problem, particularly on older machines with not so much\\ndisk. Do we really need to maintain a separate checkout for each\\nbranch? It seems like a fresh checkout from the repo would be\\nlittle more expensive than the current copy-a-checkout process.)\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:23:40 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 10:23 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> What concerns me here is that we not get into a position where we're\\n> effectively still maintaining EOL'd versions. Looking at the git\\n> history yesterday reminded me that we had such a situation back in\\n> the early 7.x days. I can see that I still occasionally made commits\\n> into 7.1 and 7.2 years after the last releases of those branches,\\n> which ended up being a complete waste of effort. There was no policy\\n> guiding what to back-patch into what branches, partly because we\\n> didn't have a defined EOL policy then. So I want to have a policy\\n> (and a pretty tight one) before I'll go back to doing that.\\n>\\n> Roughly speaking, I think the policy should be \\\"no feature bug fixes,\\n> not even security fixes, for EOL'd branches; only fixes that are\\n> minimally necessary to make it build on newer platforms\\\". And\\n> I want to have a sunset provision even for that. Fixing every branch\\n> forevermore doesn't scale.\\n\\nSure, but you can ameliorate that a lot by just saying it's something\\npeople have the *option* to do, not something anybody is *expected* to\\ndo. I agree it's best if we continue to discourage back-patching bug\\nfixes into supported branches, but I also think we don't need to be\\ntoo stringent about this. What I think we don't want is, for example,\\nsomebody working at company X deciding to back-patch all the bug fixes\\nthat customers of company X cares about into our back-branches, but\\nnot the other ones. But on the other hand if somebody is trying to\\nbenchmark or test compatibility an old branch and it keeps crashing\\nbecause of some bug, telling them that they're not allowed to fix that\\nbug because it's not a sufficiently-minimal change to a dead branch is\\nkind of ridiculous. In other words, if you try to police every change\\nanyone wants to make, e.g. \\\"well I know that would help YOU build on a\\nnewer platform but it doesn't seem like it meets the criteria of the\\nminimum necessary change to make it build on a newer platform,\\\" then\\nyou might as well just give up now. Nobody cares about the older\\nbranches enough to put work into fixing whatever's wrong and then\\nhaving to argue about whether that work ought to be thrown away\\nanyway.\\n\\n> There's also the question of how we get to a working state in the\\n> first place -- as we found upthread, there's a fair-sized amount\\n> of work to do just to restore buildability right now, for anything\\n> that was EOL'd more than a year or two back. I'm not volunteering\\n> for that, but somebody would have to to get things off the ground.\\n\\nRight.\\n\\n> Also, I concur with Andrew's point that we'd really have to have\\n> buildfarm support. However, this might not be as bad as it seems.\\n> In principle we might just need to add resurrected branches back to\\n> the branches_to_build list. Given my view of what the back-patching\\n> policy ought to be, a new build in an old branch might only be\\n> required a couple of times a year, which would not be an undue\\n> investment of buildfarm resources. (Hmmm ... but disk space could\\n> become a problem, particularly on older machines with not so much\\n> disk. Do we really need to maintain a separate checkout for each\\n> branch? It seems like a fresh checkout from the repo would be\\n> little more expensive than the current copy-a-checkout process.)\\n\\nI suppose it would be useful if we had the ability to do new runs only\\nwhen the source code has changed...\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:40:29 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Mon, Oct 25, 2021 at 10:23 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Roughly speaking, I think the policy should be \\\"no feature bug fixes,\\n>> not even security fixes, for EOL'd branches; only fixes that are\\n>> minimally necessary to make it build on newer platforms\\\". And\\n>> I want to have a sunset provision even for that. Fixing every branch\\n>> forevermore doesn't scale.\\n\\n> Sure, but you can ameliorate that a lot by just saying it's something\\n> people have the *option* to do, not something anybody is *expected* to\\n> do. I agree it's best if we continue to discourage back-patching bug\\n> fixes into supported branches, but I also think we don't need to be\\n> too stringent about this.\\n\\nActually, I think we do. If I want to test against 7.4, ISTM I want\\nto test against the last released 7.4 version, not something with\\narbitrary later changes. Otherwise, what exactly is the point?\\n\\n>> In principle we might just need to add resurrected branches back to\\n>> the branches_to_build list. Given my view of what the back-patching\\n>> policy ought to be, a new build in an old branch might only be\\n>> required a couple of times a year, which would not be an undue\\n>> investment of buildfarm resources.\\n\\n> I suppose it would be useful if we had the ability to do new runs only\\n> when the source code has changed...\\n\\nUh, don't we have that already? I know you can configure a buildfarm\\nanimal to force a run at least every-so-often, but it's not required,\\nand I don't think it's even the default.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:00:42 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-25, Tom Lane wrote:\\n\\n> Roughly speaking, I think the policy should be \\\"no feature bug fixes,\\n> not even security fixes, for EOL'd branches; only fixes that are\\n> minimally necessary to make it build on newer platforms\\\". And\\n> I want to have a sunset provision even for that. Fixing every branch\\n> forevermore doesn't scale.\\n\\nAgreed. I think dropping such support at the same time we drop\\npsql/pg_dump support is a decent answer to that. That meets the stated\\npurpose of being able to test such support, and also it moves forward\\naccording to subjective choice per development needs.\\n\\n> Also, I concur with Andrew's point that we'd really have to have\\n> buildfarm support. However, this might not be as bad as it seems.\\n> In principle we might just need to add resurrected branches back to\\n> the branches_to_build list.\\n\\nWell, we would add them to *some* list, but not to the one used by stock\\nBF members -- not only because of the diskspace issue but also because\\nof the time to build. I suggest that we should have a separate\\nlist-of-branches file that would only be used by BF members especially\\nconfigured to do so; and hopefully we won't allow more than a handful\\nanimals to do that but rather a well-chosen subset, and also maybe allow\\nonly GCC rather than try to support other compilers. (There's no need\\nto ensure compilability on any Windows platform, for example.)\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\\"Ed is the standard text editor.\\\"\\n http://groups.google.com/group/alt.religion.emacs/msg/8d94ddab6a9b0ad3\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:05:22 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Actually, I think we do. If I want to test against 7.4, ISTM I want\\n> to test against the last released 7.4 version, not something with\\n> arbitrary later changes. Otherwise, what exactly is the point?\\n\\n1. You're free to check out any commit you like.\\n\\n2. Nothing I said can reasonably be confused with \\\"let's allow\\narbitrary later changes.\\\"\\n\\n> Uh, don't we have that already? I know you can configure a buildfarm\\n> animal to force a run at least every-so-often, but it's not required,\\n> and I don't think it's even the default.\\n\\nOh, OK. I wonder how that plays with the buildfarm status page's\\ndesire to drop old results that are more than 30 days old. I guess\\nyou'd just need to force a run at least every 28 days or something.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:09:04 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 11:09, Robert Haas wrote:\\n> On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Actually, I think we do. If I want to test against 7.4, ISTM I want\\n>> to test against the last released 7.4 version, not something with\\n>> arbitrary later changes. Otherwise, what exactly is the point?\\n> 1. You're free to check out any commit you like.\\n>\\n> 2. Nothing I said can reasonably be confused with \\\"let's allow\\n> arbitrary later changes.\\\"\\n>\\n>> Uh, don't we have that already? I know you can configure a buildfarm\\n>> animal to force a run at least every-so-often, but it's not required,\\n>> and I don't think it's even the default.\\n\\n\\nYes, in fact its rather discouraged. The default is just to build when\\nthere's a code change detected.\\n\\n\\n> Oh, OK. I wonder how that plays with the buildfarm status page's\\n> desire to drop old results that are more than 30 days old. I guess\\n> you'd just need to force a run at least every 28 days or something.\\n>\\n\\nWell, we could do that, or we could modify the way the server does the\\nstatus. The table it's based on has the last 500 records for each branch\\nfor each animal, so the data is there.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:25:00 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Mon, Oct 25, 2021 at 11:00 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Actually, I think we do. If I want to test against 7.4, ISTM I want\\n>> to test against the last released 7.4 version, not something with\\n>> arbitrary later changes. Otherwise, what exactly is the point?\\n\\n> 1. You're free to check out any commit you like.\\n\\nYeah, and get something that won't build. If there's any point\\nto this work at all, it has to be that we'll maintain the closest\\npossible buildable approximation to the last released version.\\n\\n> Oh, OK. I wonder how that plays with the buildfarm status page's\\n> desire to drop old results that are more than 30 days old. I guess\\n> you'd just need to force a run at least every 28 days or something.\\n\\nI don't think it's a problem. If we haven't committed anything to\\nbranch X in a month, it's likely not interesting. It might be worth\\nhaving a way to get the website to show results further back than\\na month, but that doesn't need to be in the default view.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:26:26 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 10:23, Tom Lane wrote:\\n>\\n> Also, I concur with Andrew's point that we'd really have to have\\n> buildfarm support. However, this might not be as bad as it seems.\\n> In principle we might just need to add resurrected branches back to\\n> the branches_to_build list. Given my view of what the back-patching\\n> policy ought to be, a new build in an old branch might only be\\n> required a couple of times a year, which would not be an undue\\n> investment of buildfarm resources. (Hmmm ... but disk space could\\n> become a problem, particularly on older machines with not so much\\n> disk. Do we really need to maintain a separate checkout for each\\n> branch? It seems like a fresh checkout from the repo would be\\n> little more expensive than the current copy-a-checkout process.)\\n\\n\\nIf you set it up with these settings then the disk space used is minimal:\\n\\n git_use_workdirs => 1,\\n rm_worktrees => 1,\\n\\nSo I have this on crake:\\n\\n andrew@emma:root $ du -sh REL*/pgsql\\n 5.5M REL_10_STABLE/pgsql\\n 5.6M REL_11_STABLE/pgsql\\n 5.6M REL_12_STABLE/pgsql\\n 5.6M REL_13_STABLE/pgsql\\n 2.0M REL_14_STABLE/pgsql\\n 2.6M REL9_5_STABLE/pgsql\\n 5.5M REL9_6_STABLE/pgsql\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:28:04 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 11:05, Alvaro Herrera wrote:\\n>\\n>> Also, I concur with Andrew's point that we'd really have to have\\n>> buildfarm support. However, this might not be as bad as it seems.\\n>> In principle we might just need to add resurrected branches back to\\n>> the branches_to_build list.\\n> Well, we would add them to *some* list, but not to the one used by stock\\n> BF members -- not only because of the diskspace issue but also because\\n> of the time to build. I suggest that we should have a separate\\n> list-of-branches file that would only be used by BF members especially\\n> configured to do so; and hopefully we won't allow more than a handful\\n> animals to do that but rather a well-chosen subset, and also maybe allow\\n> only GCC rather than try to support other compilers. (There's no need\\n> to ensure compilability on any Windows platform, for example.)\\n\\n\\nWell, we do build with gcc on Windows :-) But yes, maybe we should make\\nthis a more opt-in process.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:30:40 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Alvaro Herrera <alvherre@alvh.no-ip.org> writes:\\n> On 2021-Oct-25, Tom Lane wrote:\\n>> Also, I concur with Andrew's point that we'd really have to have\\n>> buildfarm support. However, this might not be as bad as it seems.\\n>> In principle we might just need to add resurrected branches back to\\n>> the branches_to_build list.\\n\\n> Well, we would add them to *some* list, but not to the one used by stock\\n> BF members -- not only because of the diskspace issue but also because\\n> of the time to build. I suggest that we should have a separate\\n> list-of-branches file that would only be used by BF members especially\\n> configured to do so; and hopefully we won't allow more than a handful\\n> animals to do that but rather a well-chosen subset, and also maybe allow\\n> only GCC rather than try to support other compilers. (There's no need\\n> to ensure compilability on any Windows platform, for example.)\\n\\nMeh. I don't think that's a great approach, because then we're only\\nensuring buildability on a rather static set of platforms. The whole\\npoint here is that when release N+1 of $your_favorite_platform arrives,\\nwe want to know whether the old branches still build on it. If the\\ndefault behavior for new buildfarm animals is to ignore the old branches,\\nwe're much less likely to find that out.\\n\\nIt's also unclear to me why we'd leave Windows out of this discussion.\\nWe keep saying we want to encourage Windows-based hackers to contribute,\\nso doesn't that require testing it on the same basis as other platforms?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:33:17 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Andrew Dunstan <andrew@dunslane.net> writes:\\n> On 10/25/21 10:23, Tom Lane wrote:\\n>> (Hmmm ... but disk space could\\n>> become a problem, particularly on older machines with not so much\\n>> disk. Do we really need to maintain a separate checkout for each\\n>> branch? It seems like a fresh checkout from the repo would be\\n>> little more expensive than the current copy-a-checkout process.)\\n\\n> If you set it up with these settings then the disk space used is minimal:\\n> git_use_workdirs => 1,\\n> rm_worktrees => 1,\\n\\nMaybe we should make those the defaults? AFAICS the current\\ndefault setup uses circa 200MB per back branch, even between runs.\\nI'm not sure what that is buying us.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:38:51 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-25, Tom Lane wrote:\\n\\n> It's also unclear to me why we'd leave Windows out of this discussion.\\n> We keep saying we want to encourage Windows-based hackers to contribute,\\n> so doesn't that require testing it on the same basis as other platforms?\\n\\nTesting of in-support branches, sure -- I don't propose to break that.\\nBut this is all about providing *some* server against which to test\\nclient-side changes with, right? Not to test the old servers\\nthemselves. Looking at Amit K's \\\"Postgres person of the week\\\" interview[1]\\nand remembering conversations with David Rowley, Windows hackers seem\\nperfectly familiar with getting Linux builds going, so we wouldn't need\\nto force MSVC fixes in order for them to have old servers available.\\n\\nBut anyway, I was thinking that the fixes required for MSVC buildability\\nwere quite invasive, but on looking again they don't seem all that\\nbad[2], so I withdraw that comment.\\n\\nI do think you have moved the goalposts: to reiterate what I said above,\\nI thought what we wanted was to have *some* server in order to test\\nclient-side changes with; not to be able to get a server running on\\nevery possible platform. I'm not really on board with the idea that old\\nbranches have to be buildable everywhere all the time.\\n\\n[1] https://postgresql.life/post/amit_kapila/\\n[2] e.g., commit 2b1394fc2b52a2573d08aa626e7b49568f27464e\\n\\n-- \\nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:25:04 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Alvaro Herrera <alvherre@alvh.no-ip.org> writes:\\n> I do think you have moved the goalposts: to reiterate what I said above,\\n> I thought what we wanted was to have *some* server in order to test\\n> client-side changes with; not to be able to get a server running on\\n> every possible platform. I'm not really on board with the idea that old\\n> branches have to be buildable everywhere all the time.\\n\\nAgreed, that might be too much work compared to the value. But if we're\\nto be selective about support for this, I'm unclear on how we decide\\nwhich platforms are supported --- and, more importantly, how we keep\\nthat list up to date over time.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 12:43:15 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-22 19:30:25 -0400, Tom Lane wrote:\\n> Yeah. I checked into when it was that we dropped pre-8.0 support\\n> from pg_dump, and the answer is just about five years ago (64f3524e2).\\n> So moving the bar forward by five releases isn't at all out of line.\\n> 8.4 would be eight years past EOL by the time v15 comes out.\\n\\nI'd really like us to adopt a \\\"default\\\" policy on this. I think it's a waste\\nto spend time every few years arguing what exact versions to drop. I'd much\\nrather say that, unless there are concrete reasons to deviate from that, we\\nprovide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\\nfor 5 releases or something like that.\\n\\nIt's fine to not actually spend the time to excise support for old versions\\nevery release if not useful, but we should be able to \\\"just do it\\\" whenever\\nversion compat is a meaningful hindrance.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 09:56:20 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 10:23:40 -0400, Tom Lane wrote:\\n> Also, I concur with Andrew's point that we'd really have to have\\n> buildfarm support. However, this might not be as bad as it seems.\\n> In principle we might just need to add resurrected branches back to\\n> the branches_to_build list. Given my view of what the back-patching\\n> policy ought to be, a new build in an old branch might only be\\n> required a couple of times a year, which would not be an undue\\n> investment of buildfarm resources.\\n\\nFWIW, if helpful I could easily specify a few additional branches to some of\\nmy buildfarm animals. Perhaps serinus/flaviventris (snapshot gcc wo/w\\noptimizations) so we'd see problems coming early? I could also add\\nrecent-clang one.\\n\\nI think doing this to a few designated animals is a better idea than wasting\\ncycles and space on a lot of animals.\\n\\n\\n> It seems like a fresh checkout from the repo would be little more expensive\\n> than the current copy-a-checkout process.)\\n\\nI haven't looked in detail, but from what I've seen in the logs the\\nis-there-anything-new check is already not cheap, and does a checkout / update\\nof the git directory.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:06:57 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-22 19:30:25 -0400, Tom Lane wrote:\\n>> Yeah. I checked into when it was that we dropped pre-8.0 support\\n>> from pg_dump, and the answer is just about five years ago (64f3524e2).\\n>> So moving the bar forward by five releases isn't at all out of line.\\n>> 8.4 would be eight years past EOL by the time v15 comes out.\\n\\n> I'd really like us to adopt a \\\"default\\\" policy on this. I think it's a waste\\n> to spend time every few years arguing what exact versions to drop. I'd much\\n> rather say that, unless there are concrete reasons to deviate from that, we\\n> provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\\n> for 5 releases or something like that.\\n\\nI agree with considering something like that to be the minimum support\\npolicy, but the actual changes need a bit more care. For example, when\\nwe last did this, the technical need was just to drop pre-7.4 versions,\\nbut we chose to make the cutoff 8.0 on the grounds that that was more\\nunderstandable to users [1]. In the same way, I'm thinking of moving the\\ncutoff to 9.0 now, although 8.4 would be sufficient from a technical\\nstandpoint.\\n\\nOTOH, in the new world of one-part major versions, it's less clear that\\nthere will be obvious division points for future cutoff changes. Maybe\\nversions-divisible-by-five would work? Or versions divisible by ten,\\nbut experience so far suggests that we'll want to move the cutoff more\\noften than once every ten years.\\n\\n\\t\\t\\tregards, tom lane\\n\\n[1] https://www.postgresql.org/message-id/flat/2661.1475849167%40sss.pgh.pa.us\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:09:43 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-25 10:23:40 -0400, Tom Lane wrote:\\n>> It seems like a fresh checkout from the repo would be little more expensive\\n>> than the current copy-a-checkout process.)\\n\\n> I haven't looked in detail, but from what I've seen in the logs the\\n> is-there-anything-new check is already not cheap, and does a checkout / update\\n> of the git directory.\\n\\nYeah, you probably need a checkout to apply the rule about don't rebuild\\nafter documentation-only changes. But it seems like the case where the\\nbranch tip hasn't moved at all could be optimized fairly easily. I'm not\\nsure it's worth the trouble to add code for that given our current usage\\nof the buildfarm; but if we were to start tracking branches that only\\nchange a couple of times a year, it would be.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:14:19 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 12:43:15 -0400, Tom Lane wrote:\\n> Agreed, that might be too much work compared to the value. But if we're\\n> to be selective about support for this, I'm unclear on how we decide\\n> which platforms are supported --- and, more importantly, how we keep\\n> that list up to date over time.\\n\\nI honestly think that if we just test on linux with a single distribution,\\nwe're already covering most of the benefit. From memory there have been two\\nrough classes of doesn't-build-anymore:\\n\\n1) New optimizations / warnings. At least between gcc and clang, within a year\\n or two, most of the issues end up being visible with the other compiler\\n too. These aren't particularly distribution / OS specific.\\n\\n2) Library dependencies cause problems, like the ssl detection mentioned\\n elsewhere in this thread. This is also not that OS dependent. It's also not\\n that clear that we can do something about the issues with a reasonable\\n amount of effort in all cases. It's easy enough if it's just a minor\\n configure fix, but we'd not want to backpatch larger SSL changes or such.\\n\\n\\nMaybe there's also a case for building older releases with msvc, but that\\nseems like a pain due to the msvc project generation needing to support a\\nspecific version of msvc.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:17:20 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 13:09:43 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> > I'd really like us to adopt a \\\"default\\\" policy on this. I think it's a waste\\n> > to spend time every few years arguing what exact versions to drop. I'd much\\n> > rather say that, unless there are concrete reasons to deviate from that, we\\n> > provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\\n> > for 5 releases or something like that.\\n> \\n> I agree with considering something like that to be the minimum support\\n> policy, but the actual changes need a bit more care. For example, when\\n> we last did this, the technical need was just to drop pre-7.4 versions,\\n> but we chose to make the cutoff 8.0 on the grounds that that was more\\n> understandable to users [1]. In the same way, I'm thinking of moving the\\n> cutoff to 9.0 now, although 8.4 would be sufficient from a technical\\n> standpoint.\\n\\nI think that'd be less of a concern if we had a documented policy\\nsomewhere. It'd not be hard to include a version table in that policy to make\\nit easier to understand. We could even add it to the table in\\nhttps://www.postgresql.org/support/versioning/ or something similar.\\n\\n\\n> OTOH, in the new world of one-part major versions, it's less clear that\\n> there will be obvious division points for future cutoff changes. Maybe\\n> versions-divisible-by-five would work?\\n\\nI think that's more confusing than helpful, because the support timeframes\\nthen differ between releases. It's easier to just subtract a number of major\\nreleases for from a specific major version. Especially if there's a table\\nsomewhere.\\n\\n\\n> Or versions divisible by ten, but experience so far suggests that we'll want\\n> to move the cutoff more often than once every ten years.\\n\\nYes, I think that'd be quite a bit too restrictive.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:24:13 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 13:06, Andres Freund wrote:\\n> Hi,\\n>\\n> On 2021-10-25 10:23:40 -0400, Tom Lane wrote:\\n>> Also, I concur with Andrew's point that we'd really have to have\\n>> buildfarm support. However, this might not be as bad as it seems.\\n>> In principle we might just need to add resurrected branches back to\\n>> the branches_to_build list. Given my view of what the back-patching\\n>> policy ought to be, a new build in an old branch might only be\\n>> required a couple of times a year, which would not be an undue\\n>> investment of buildfarm resources.\\n> FWIW, if helpful I could easily specify a few additional branches to some of\\n> my buildfarm animals. Perhaps serinus/flaviventris (snapshot gcc wo/w\\n> optimizations) so we'd see problems coming early? I could also add\\n> recent-clang one.\\n>\\n> I think doing this to a few designated animals is a better idea than wasting\\n> cycles and space on a lot of animals.\\n\\n\\nRight now the server will only accept results for something in\\nbranches_of_interest.txt. So we would need to modify that.\\n\\n\\nI tend to agree that we don't need a whole lot of cross platform testing\\nhere.\\n\\n\\n>\\n>\\n>> It seems like a fresh checkout from the repo would be little more expensive\\n>> than the current copy-a-checkout process.)\\n> I haven't looked in detail, but from what I've seen in the logs the\\n> is-there-anything-new check is already not cheap, and does a checkout / update\\n> of the git directory.\\n>\\n>\\n\\nIf you have removed the work tree (with the \\\"rm_worktrees => 1\\\" setting)\\nthen it restores it by doing a checkout. It then does a \\\"git fetch\\\", and\\nthen as you say looks to see if there is anything new. If you know of a\\nbetter way to manage it then please let me know. On crake (which is\\nactually checking out four different repos) the checkout step typically\\ntakes one or two seconds.\\n\\n\\nCopying the work tree can take a few seconds - to avoid that on\\nUnix/msys use vpath builds.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:29:11 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Anyway, to get back to the original point ...\\n\\nNo one has spoken against moving up the cutoff for pg_dump support,\\nso I did a very quick pass to see how much code could be removed.\\nThe answer is right about 1000 lines, counting both pg_dump and\\npg_upgrade, so it seems like it's worth doing independently of the\\nunnest() issue.\\n\\nThe attached is just draft-quality, because I don't really want\\nto pursue the point until after committing the pg_dump changes\\nbeing discussed in the other thread. If I push this first it'll\\nbreak a lot of those patches. (Admittedly, pushing those first\\nwill break this one, but this one is a lot easier to re-do.)\\n\\nBTW, while looking at pg_upgrade I chanced to notice\\ncheck_for_isn_and_int8_passing_mismatch(), which seems like it's\\nnot well thought out at all. It's right that contrib/isn will\\nnot upgrade nicely if the target cluster has a different\\nfloat8_pass_by_value setting from the source. What's wrong is\\nthe assumption that no other extension has the same issue.\\nWe invented and publicized the \\\"LIKE type\\\" option for CREATE TYPE\\nprecisely so that people could build types that act just like isn,\\nso it seems pretty foolish to imagine that no one has done so.\\n\\nI think we should nuke check_for_isn_and_int8_passing_mismatch()\\nand just refuse to upgrade if float8_pass_by_value differs, full stop.\\nI can see little practical need to allow that case.\\n\\n\\t\\t\\tregards, tom lane\",\n \"msg_date\": \"Mon, 25 Oct 2021 18:52:18 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 11:38:51AM -0400, Tom Lane wrote:\\n> Andrew Dunstan <andrew@dunslane.net> writes:\\n> > On 10/25/21 10:23, Tom Lane wrote:\\n> >> (Hmmm ... but disk space could\\n> >> become a problem, particularly on older machines with not so much\\n> >> disk. Do we really need to maintain a separate checkout for each\\n> >> branch? It seems like a fresh checkout from the repo would be\\n> >> little more expensive than the current copy-a-checkout process.)\\n> \\n> > If you set it up with these settings then the disk space used is minimal:\\n> > �� � git_use_workdirs => 1,\\n> > �� � rm_worktrees => 1,\\n> \\n> Maybe we should make those the defaults? AFAICS the current\\n> default setup uses circa 200MB per back branch, even between runs.\\n> I'm not sure what that is buying us.\\n\\nMaybe git's shared/\\\"alternates\\\" would be helpful to minimize the size of\\n.git/objects?\\n\\nI'm not sure - it looks like the BF client does its own stuff with symlinks.\\nIs that for compatibility with old git ?\\nhttps://github.com/PGBuildFarm/client-code/blob/main/PGBuild/SCM.pm\\n\\nIf you \\\"clone\\\" a local location, it uses hard links by default.\\nIf you use --shared or --reference, then it uses references to the configured\\n\\\"alternates\\\", if any.\\n\\nIn both cases, .git/objects requires no additional space (but the \\\"checked out\\\"\\ncopy still takes up however much space).\\n\\n$ mkdir tmp\\n$ git clone --quiet ./postgresql tmp/pg\\n$ du -sh tmp/pg\\n492M tmp/pg\\n\\n$ rm -fr tmp/pg\\n$ git clone --quiet --shared ./postgresql tmp/pg\\n$ du -sh tmp/pg\\n124M tmp/pg\\n\\n-- \\nJustin\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 18:12:56 -0500\",\n \"msg_from\": \"Justin Pryzby <pryzby@telsasoft.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 19:12, Justin Pryzby wrote:\\n> On Mon, Oct 25, 2021 at 11:38:51AM -0400, Tom Lane wrote:\\n>> Andrew Dunstan <andrew@dunslane.net> writes:\\n>>> On 10/25/21 10:23, Tom Lane wrote:\\n>>>> (Hmmm ... but disk space could\\n>>>> become a problem, particularly on older machines with not so much\\n>>>> disk. Do we really need to maintain a separate checkout for each\\n>>>> branch? It seems like a fresh checkout from the repo would be\\n>>>> little more expensive than the current copy-a-checkout process.)\\n>>> If you set it up with these settings then the disk space used is minimal:\\n>>> git_use_workdirs => 1,\\n>>> rm_worktrees => 1,\\n>> Maybe we should make those the defaults? AFAICS the current\\n>> default setup uses circa 200MB per back branch, even between runs.\\n>> I'm not sure what that is buying us.\\n> Maybe git's shared/\\\"alternates\\\" would be helpful to minimize the size of\\n> .git/objects?\\n>\\n> I'm not sure - it looks like the BF client does its own stuff with symlinks.\\n> Is that for compatibility with old git ?\\n> https://github.com/PGBuildFarm/client-code/blob/main/PGBuild/SCM.pm\\n\\n\\nIt's actually based on the git contrib script git-new-workdir. And using\\nit is the default (except on Windows, where it doesn't work due to\\nissues with symlinking plain files :-( )\\n\\nSince what we have is not broken I'm not inclined to fix it.\\n\\nThe issue Tom was complaining about is different, namely the storage for\\neach branch's working tree. As I mentioned upthread, you can alleviate\\nthat by setting \\\"rm_worktrees => 1\\\" in your config. That works\\neverywhere, including Windows, and will be the default in the next\\nbuildfarm release.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n-- \\n\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:41:32 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 10/25/21 13:09, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n>> On 2021-10-22 19:30:25 -0400, Tom Lane wrote:\\n>>> Yeah. I checked into when it was that we dropped pre-8.0 support\\n>>> from pg_dump, and the answer is just about five years ago (64f3524e2).\\n>>> So moving the bar forward by five releases isn't at all out of line.\\n>>> 8.4 would be eight years past EOL by the time v15 comes out.\\n>> I'd really like us to adopt a \\\"default\\\" policy on this. I think it's a waste\\n>> to spend time every few years arguing what exact versions to drop. I'd much\\n>> rather say that, unless there are concrete reasons to deviate from that, we\\n>> provide pg_dump compatibility for 5+3 releases, pg_upgrade for 5+1, and psql\\n>> for 5 releases or something like that.\\n> I agree with considering something like that to be the minimum support\\n> policy, but the actual changes need a bit more care. For example, when\\n> we last did this, the technical need was just to drop pre-7.4 versions,\\n> but we chose to make the cutoff 8.0 on the grounds that that was more\\n> understandable to users [1]. In the same way, I'm thinking of moving the\\n> cutoff to 9.0 now, although 8.4 would be sufficient from a technical\\n> standpoint.\\n>\\n> OTOH, in the new world of one-part major versions, it's less clear that\\n> there will be obvious division points for future cutoff changes. Maybe\\n> versions-divisible-by-five would work? Or versions divisible by ten,\\n> but experience so far suggests that we'll want to move the cutoff more\\n> often than once every ten years.\\n>\\n> \\t\\n\\n\\npg_upgrade claims to be able to operate on 8.4, which might be all the\\nbetter for some regular testing (which this could enable), so that seems\\nto me more like where the cutoff should be at least for this round.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:59:34 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"I was thinking a bit about formulating a policy for pg_dump backward\\ncompatibility, based on the discussions in this thread.\\n\\nPremises and preparatory thoughts:\\n\\n- Users (and developers) want pg_dump to support server versions that\\n are much older than non-EOL versions.\\n\\n- Less critically, much-longer backward compatibility has also\\n historically been provided for psql, so keeping those two the same\\n would make sense.\\n\\n- The policy for other client-side tools (list at [0]) is less clear\\n and arguably less important. I suggest we focus on pg_dump and psql\\n first, and then we can decide for the rest whether they want to\\n match a longer window, a shorter window, or a different policy\\n altogether (e.g., ecpg).\\n\\n- If we are going to maintain compatibility with very old server\\n versions, we need to make sure the older server versions can at\\n least still be built while an allegedly-compatible client tool is\\n under support.\\n\\n[0]: https://www.postgresql.org/docs/devel/reference-client.html\\n\\nProposal:\\n\\n* pg_dump and psql will maintain compatibility with servers at least\\n ten major releases back.\\n\\nThis assumes a yearly major release cadence.\\n\\nI use the count of major releases here instead of some number of\\nyears, as was previously discussed, for two reasons. First, it makes\\ncomputing the cutoff easier, because you are not bothered by whether\\nsome old release was released a few weeks before or after the\\nequivalent date in the current year for the new release. Second,\\nthere is no ambiguity about what happens during the lifetime of a\\nmajor release: If major release $NEW supports major release $OLD at\\nthe time of $NEW's release, then that stays the same for the whole\\nlife of $NEW; we don't start dropping support for $OLD in $NEW.5\\nbecause a year has passed.\\n\\nI say \\\"at least\\\" because I wouldn't go around aggressively removing\\nsupport for old releases. If $NEW is supposed to support 9.5 but\\nthere is code that says `if (version > 9.4)`, I would not s/9.4/9.5/\\nthat unless that code is touched for other reasons.\\n\\nThen ...\\n\\n* We keep old major release branches buildable as long as a new major\\n release that has support for that old release is under support.\\n\\nBuildable for this purpose means just enough that you can use it to\\ntest pg_dump and psql. This probably includes being able to run make\\ninstallcheck and use pg_dump and psql against the regression database.\\nIt does not require support for any additional build-time options that\\nare not required for this purpose (e.g., new OpenSSL releases).\\nConversely, it should be buildable with default compiler options. For\\nexample, if it fails to build and test cleanly unless you use -O0,\\nthat should be fixed. Fixes in very-old branches should normally be\\nbackpatches that have stabilized in under-support branches. Changes\\nthat silence compiler warnings in newer compilers are by themselves\\nnot considered a backpatch-worthy fix.\\n\\n(In some cases, the support window of typical compilers should be\\nconsidered. If adding support for a very new compiler with new\\naggressive optimizations turns out to be too invasive, then that\\ncompiler might simply be declared not supported for that release. But\\nwe should strive to support at least one compiler that still has some\\nupstream support.)\\n\\nThis keep-buildable effort is on an as-needed basis. There is no\\nrequirement to keep the buildability current at all times, and there\\nis no requirement to keep all platforms working at all times.\\nObviously, any changes made to improve buildability should not\\nknowingly adversely affect other platforms.\\n\\n(The above could be reconsidered if buildfarm support is available,\\nbut I don't consider that necessary and wouldn't want to wait for it.)\\n\\nThere is no obligation on anyone backpatching fixes to supported\\nbranches to also backpatch them to keep-buildable branches. It is up\\nto those working on pg_dump/psql and requiring testing against old\\nversions to pick available fixes and apply them to keep-buildable\\nbranches as needed.\\n\\nFinally, none of this is meant to imply that there will be any\\nreleases, packages, security support, production support, or community\\nsupport for keep-buildable branches. This is a Git-repo-only,\\ndeveloper-focusing effort.\\n\\nExample under this proposal:\\n\\nPG 15 supports PG 9.2\\nPG 14 supports PG 9.1\\nPG 13 supports PG 9.0\\nPG 12 supports PG 8.4\\nPG 11 supports PG 8.3\\nPG 10 supports PG 8.2\\n\\nIn practice, the effort can focus on keeping the most recent cutoff\\nrelease buildable. So in the above example, we really only need to\\nkeep PG >=9.2 buildable to support ongoing development. The chances\\nthat some needs to touch code pertaining to older versions in\\nbackbranches is lower, so those really would need to be dealt with\\nvery rarely.\\n\\n\\nThe parent message has proposed to remove support for PG <9.0 from\\nmaster. But I think that was chosen mainly because it was a round\\nnumber. I suggest we pick a cutoff based on years, as I had\\ndescribed, and then proceed with that patch.\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Dec 2021 11:01:47 +0100\",\n \"msg_from\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 2, 2021 at 5:01 AM Peter Eisentraut\\n<peter.eisentraut@enterprisedb.com> wrote:\\n> * pg_dump and psql will maintain compatibility with servers at least\\n> ten major releases back.\\n>\\n> * We keep old major release branches buildable as long as a new major\\n> release that has support for that old release is under support.\\n>\\n> Buildable for this purpose means just enough that you can use it to\\n> test pg_dump and psql. This probably includes being able to run make\\n> installcheck and use pg_dump and psql against the regression database.\\n> It does not require support for any additional build-time options that\\n> are not required for this purpose (e.g., new OpenSSL releases).\\n> Conversely, it should be buildable with default compiler options. For\\n> example, if it fails to build and test cleanly unless you use -O0,\\n> that should be fixed. Fixes in very-old branches should normally be\\n> backpatches that have stabilized in under-support branches. Changes\\n> that silence compiler warnings in newer compilers are by themselves\\n> not considered a backpatch-worthy fix.\\n\\nSounds reasonable. It doesn't really make sense to insist that the\\ntools have to be compatible with releases that most developers can't\\nactually build.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Dec 2021 06:54:04 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\\n> Proposal:\\n\\n> * pg_dump and psql will maintain compatibility with servers at least\\n> ten major releases back.\\n> * We keep old major release branches buildable as long as a new major\\n> release that has support for that old release is under support.\\n\\n> This assumes a yearly major release cadence.\\n\\nIf the point is to not have to count dates carefully, why does the cadence\\nmatter?\\n\\n> I say \\\"at least\\\" because I wouldn't go around aggressively removing\\n> support for old releases. If $NEW is supposed to support 9.5 but\\n> there is code that says `if (version > 9.4)`, I would not s/9.4/9.5/\\n> that unless that code is touched for other reasons.\\n\\nI can get behind something roughly like this, but I wonder if it wouldn't\\nbe better to formulate the policy in a reactive way, i.e. when X happens\\nwe'll do Y. If we don't plan to proactively remove some code every year,\\nthen it seems like the policy really is more like \\\"when something breaks,\\nthen we'll make an attempt to keep it working if the release is less than\\nten majors back; otherwise we'll declare that release no longer\\nbuildable.\\\"\\n\\nHowever, this'd imply continuing to test against releases that are out of\\nthe ten-year window but have not yet been found to be broken. Not sure\\nif that's a useful expenditure of test resources or not.\\n\\n> Buildable for this purpose means just enough that you can use it to\\n> test pg_dump and psql. This probably includes being able to run make\\n> installcheck and use pg_dump and psql against the regression database.\\n> It does not require support for any additional build-time options that\\n> are not required for this purpose (e.g., new OpenSSL releases).\\n\\nI agree with the idea of being conservative about what outside\\ndependencies we will worry about for \\\"buildable\\\" old versions.\\n(Your nearby message about Python breakage is a good example of\\nwhy we must limit that.) But I wonder about, say, libxml or libicu,\\nor even if we can afford to drop all the non-plpgsql PLs. An\\nexample of why that seems worrisome is that it's not clear we'd\\nhave any meaningful coverage of transforms in pg_dump with no PLs.\\nI don't have any immediate proposal here, but it seems like an area\\nthat needs some thought and specific policy.\\n\\n> Example under this proposal:\\n\\n> PG 15 supports PG 9.2\\n> PG 14 supports PG 9.1\\n> PG 13 supports PG 9.0\\n> PG 12 supports PG 8.4\\n> PG 11 supports PG 8.3\\n> PG 10 supports PG 8.2\\n\\nI was going to express concern about having to resurrect branches\\nback to 8.2, but:\\n\\n> In practice, the effort can focus on keeping the most recent cutoff\\n> release buildable. So in the above example, we really only need to\\n> keep PG >=9.2 buildable to support ongoing development. The chances\\n> that some needs to touch code pertaining to older versions in\\n> backbranches is lower, so those really would need to be dealt with\\n> very rarely.\\n\\nOK. Also, when you do need to check that, there are often other ways\\nthan rebuilding the old branch on modern platforms --- people may\\nwell have still-executable builds laying about, even if rebuilding\\nfrom source would be problematic.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 02 Dec 2021 12:30:45 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 12/2/21 12:30, Tom Lane wrote:\\n>\\n>> In practice, the effort can focus on keeping the most recent cutoff\\n>> release buildable. So in the above example, we really only need to\\n>> keep PG >=9.2 buildable to support ongoing development. The chances\\n>> that some needs to touch code pertaining to older versions in\\n>> backbranches is lower, so those really would need to be dealt with\\n>> very rarely.\\n> OK. Also, when you do need to check that, there are often other ways\\n> than rebuilding the old branch on modern platforms --- people may\\n> well have still-executable builds laying about, even if rebuilding\\n> from source would be problematic.\\n>\\n> \\t\\t\\t\\n\\n\\n\\nI have a very old fedora instance where I can build every release back\\nto 7.2 :-) And with only slight massaging for the very old releases,\\nthese builds run on my Fedora 34 development system. Certainly 8.2 and\\nup wouldn't be a problem. Currently I have only tested building without\\nany extra libraries/PLs, but I can look at other combinations. So, long\\nstory short this is fairly doable at least in some environments. This\\nprovides a good use case for the work I have been doing on backwards\\ncompatibility of the TAP framework. I need to get back to that now that\\nthe great module namespace adjustment has settled down.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Dec 2021 15:46:09 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-12-02 11:01:47 +0100, Peter Eisentraut wrote:\\n> - The policy for other client-side tools (list at [0]) is less clear\\n> and arguably less important. I suggest we focus on pg_dump and psql\\n> first, and then we can decide for the rest whether they want to\\n> match a longer window, a shorter window, or a different policy\\n> altogether (e.g., ecpg).\\n\\nI think we should at least include pg_upgrade in this as well, it's pretty\\nclosely tied to at least pg_dump.\\n\\n\\n> * pg_dump and psql will maintain compatibility with servers at least\\n> ten major releases back.\\n\\nPersonally I think that's too long... It boils down keeping branches buildable\\nfor ~15 years after they've been released. That strikes me as pretty far into\\ndiminishing-returns, and steeply increasing costs, territory.\\n\\nI realize it's more complicated for users, but a policy based on supporting a\\ncertain number of out-of-support branches calculated from the newest major\\nversion is more realistic. I'd personally go for something like newest-major -\\n7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\\nsupport a few more. I think there's a considerable advantage of having one\\ncutoff date across all branches.\\n\\nThat's not to say we'd remove support for older versions from back\\nbranches. Just that we don't ever consider them supported (or test them) once\\nbelow the cutoff.\\n\\n\\n> I use the count of major releases here instead of some number of\\n> years, as was previously discussed, for two reasons. First, it makes\\n> computing the cutoff easier, because you are not bothered by whether\\n> some old release was released a few weeks before or after the\\n> equivalent date in the current year for the new release. Second,\\n> there is no ambiguity about what happens during the lifetime of a\\n> major release: If major release $NEW supports major release $OLD at\\n> the time of $NEW's release, then that stays the same for the whole\\n> life of $NEW; we don't start dropping support for $OLD in $NEW.5\\n> because a year has passed.\\n\\nMakes sense.\\n\\n\\n> * We keep old major release branches buildable as long as a new major\\n> release that has support for that old release is under support.\\n\\n> Buildable for this purpose means just enough that you can use it to\\n> test pg_dump and psql. This probably includes being able to run make\\n> installcheck and use pg_dump and psql against the regression database.\\n\\nI think we should explicitly limit the number of platforms we care about for\\nthis purpose. I don't think we should even try to keep 8.2 compile on AIX or\\nwhatnot.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 2 Dec 2021 14:16:07 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 02.12.21 18:30, Tom Lane wrote:\\n>> This assumes a yearly major release cadence.\\n> \\n> If the point is to not have to count dates carefully, why does the cadence\\n> matter?\\n\\nIf we were to change the release cadence, then it would be appropriate \\nto review this policy.\\n\\n> I can get behind something roughly like this, but I wonder if it wouldn't\\n> be better to formulate the policy in a reactive way, i.e. when X happens\\n> we'll do Y. If we don't plan to proactively remove some code every year,\\n> then it seems like the policy really is more like \\\"when something breaks,\\n> then we'll make an attempt to keep it working if the release is less than\\n> ten majors back; otherwise we'll declare that release no longer\\n> buildable.\\\"\\n\\nThis sounds like it would give license to accidentally break support for \\nold releases in the code and only fix them if someone complains. That's \\nnot really what I would be aiming for.\\n\\n> I agree with the idea of being conservative about what outside\\n> dependencies we will worry about for \\\"buildable\\\" old versions.\\n> (Your nearby message about Python breakage is a good example of\\n> why we must limit that.) But I wonder about, say, libxml or libicu,\\n> or even if we can afford to drop all the non-plpgsql PLs. An\\n> example of why that seems worrisome is that it's not clear we'd\\n> have any meaningful coverage of transforms in pg_dump with no PLs.\\n> I don't have any immediate proposal here, but it seems like an area\\n> that needs some thought and specific policy.\\n\\nYeah, I think questions like this will currently quickly lead to dead \\nends. We are talking 5 years this, 10 years that here. Everybody else \\n(apart from RHEL) is talking at best in the range 3-5 years. We will \\nhave to figure this out as we go.\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Dec 2021 17:19:47 +0100\",\n \"msg_from\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 02.12.21 23:16, Andres Freund wrote:\\n> I think we should at least include pg_upgrade in this as well, it's pretty\\n> closely tied to at least pg_dump.\\n\\nright\\n\\n>> * pg_dump and psql will maintain compatibility with servers at least\\n>> ten major releases back.\\n> \\n> Personally I think that's too long... It boils down keeping branches buildable\\n> for ~15 years after they've been released. That strikes me as pretty far into\\n> diminishing-returns, and steeply increasing costs, territory.\\n\\nWell, it is a lot, but it's on the order of what we have historically \\nprovided.\\n\\n> I realize it's more complicated for users, but a policy based on supporting a\\n> certain number of out-of-support branches calculated from the newest major\\n> version is more realistic. I'd personally go for something like newest-major -\\n> 7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\\n> support a few more. I think there's a considerable advantage of having one\\n> cutoff date across all branches.\\n\\nI'm not sure it will be clear what this would actually mean. Assume \\nPG11 supports back to 9.4 (14-7) now, but when PG15 comes out, we drop \\n9.4 support. But the PG11 code hasn't changed, and PG9.4 hasn't changed, \\nso it will most likely still work. Then we have messaging that is out \\nof sync with reality. I can see the advantage of this approach, but the \\ncommunication around it might have to be refined.\\n\\n> I think we should explicitly limit the number of platforms we care about for\\n> this purpose. I don't think we should even try to keep 8.2 compile on AIX or\\n> whatnot.\\n\\nIt's meant to be developer-facing, so only for platforms that developers \\nuse. I think that can police itself, if we define it that way.\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Dec 2021 17:29:41 +0100\",\n \"msg_from\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\\n> [ policy requiring that 9.2 and up be kept buildable, as of today ]\\n\\nI experimented to see what this would entail exactly. Using\\ncurrent macOS (Apple clang version 13.0.0) on M1 hardware,\\nI built with minimal configure options (--enable-debug --enable-cassert)\\nand ran the core regression tests. I found that commit\\n1c0cf52b3 (Use return instead of exit() in configure) is needed\\nin 9.4 and before, else we don't get through configure.\\nThat's the only fix needed to get a clean build in 9.4 and 9.3.\\n9.2 shows several compiler warnings, the scarier ones of which could\\nbe cleaned up by back-patching c74d586d2 (Fix function return type\\nconfusion). The remainder are variable-may-be-used-uninitialized\\nwarnings, which I think people are accustomed to ignoring in\\ndubious cases. In any case, I failed to get rid of them without\\nback-patching 71450d7fd (Teach compiler that ereport(>=ERROR) does\\nnot return), which seems like a bridge too far.\\n\\nI also tried 9.1, but it has multiple compile-time problems:\\n* fails to select a spinlock implementation\\n* \\\"conflicting types for 'base_yylex'\\\"\\n* strange type-conflict warnings in zlib calls\\n\\nSo at least on this platform, there are solid technical reasons\\nto select 9.2 not 9.1 as the cutoff.\\n\\nObviously, we might find some other things to fix if we checked\\nwith other compilers, or tested more than the core tests.\\nBut this much seems quite doable, and it's probably prerequisite\\nfor any further testing.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 03 Dec 2021 12:10:07 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 12/3/21 12:10, Tom Lane wrote:\\n> Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\\n>> [ policy requiring that 9.2 and up be kept buildable, as of today ]\\n> I experimented to see what this would entail exactly. Using\\n> current macOS (Apple clang version 13.0.0) on M1 hardware,\\n> I built with minimal configure options (--enable-debug --enable-cassert)\\n> and ran the core regression tests. \\n\\n\\nI've mentioned my efforts on fedora previously. But like you I used a\\nminimal configuration. So what would be reasonable to test? I know you\\nmentioned building with perl and python upthread so we could possibly\\ntest transforms. Anything else? I don't think we need to worry about all\\nthe authentication-supporting options. XML/XSLT maybe.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Dec 2021 12:28:11 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Andrew Dunstan <andrew@dunslane.net> writes:\\n> On 12/3/21 12:10, Tom Lane wrote:\\n>> I experimented to see what this would entail exactly. Using\\n>> current macOS (Apple clang version 13.0.0) on M1 hardware,\\n>> I built with minimal configure options (--enable-debug --enable-cassert)\\n>> and ran the core regression tests. \\n\\n> I've mentioned my efforts on fedora previously. But like you I used a\\n> minimal configuration. So what would be reasonable to test? I know you\\n> mentioned building with perl and python upthread so we could possibly\\n> test transforms. Anything else? I don't think we need to worry about all\\n> the authentication-supporting options. XML/XSLT maybe.\\n\\nNot sure. I think we should evaluate based on\\n1. how integral is the option, ie how much PG code can't we test if\\n we don't enable it.\\n2. how stable is the referenced code.\\n\\nPoint 2 makes me want to exclude both Python and OpenSSL, as they've\\nboth proven to be moving API targets. If we want to have tests for\\ntransform modules, plperl would be sufficient for that, and perl seems\\nto be a lot more stable than python. libxml is pretty morib^H^H^Hstable,\\nbut on the other hand it seems quite noncritical for the sorts of tests\\nwe want to run against old servers, so I'd be inclined to exclude it.\\n\\nLooking through the other configure options, the only one that I find\\nto be a hard call is --enable-nls. In theory this shouldn't be\\ncritical for testing pg_dump or psql ... but you never know, and it\\nhasn't been a stability problem. Every other one I think we could\\nignore for these purposes. At some point --with-icu might become\\ninteresting, but it isn't yet relevant to any out-of-support\\nbranches, so we can leave that call for another day.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 03 Dec 2021 13:09:31 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:\\n> On 02.12.21 23:16, Andres Freund wrote:\\n>> I realize it's more complicated for users, but a policy based on supporting a\\n>> certain number of out-of-support branches calculated from the newest major\\n>> version is more realistic. I'd personally go for something like newest-major -\\n>> 7 (i.e. 2 extra releases), but I realize that others think it's worthwhile to\\n>> support a few more. I think there's a considerable advantage of having one\\n>> cutoff date across all branches.\\n\\n> I'm not sure it will be clear what this would actually mean. Assume \\n> PG11 supports back to 9.4 (14-7) now, but when PG15 comes out, we drop \\n> 9.4 support. But the PG11 code hasn't changed, and PG9.4 hasn't changed, \\n> so it will most likely still work. Then we have messaging that is out \\n> of sync with reality. I can see the advantage of this approach, but the \\n> communication around it might have to be refined.\\n\\nI don't find this suggestion to be an improvement over Peter's original\\nformulation, for two reasons:\\n\\n* I'm not convinced that it saves us any actual work; as you say, the\\ncode doesn't stop working just because we declare it out-of-support.\\n\\n* There's a real-world use-case underneath here. If somewhere you've\\ndiscovered a decades-old server that you need to upgrade, and current\\npg_dump won't dump from it, you would like it to be well-defined\\nwhich intermediate pg_dump versions you can use. So if 10.19 can\\ndump from that hoary server, it would not be nice if 10.20 can't;\\nnor if the documentation lies to you about that based on which minor\\nversion you happen to consult.\\n\\n>> I think we should explicitly limit the number of platforms we care about for\\n>> this purpose. I don't think we should even try to keep 8.2 compile on AIX or\\n>> whatnot.\\n\\n> It's meant to be developer-facing, so only for platforms that developers \\n> use. I think that can police itself, if we define it that way.\\n\\nI agree that if you care about doing this sort of test on platform X,\\nit's up to you to patch for that. I think Andres' concern is about\\nthe amount of committer bandwidth that might be needed to handle\\nsuch patches submitted by non-committers. However, based on the\\nexperiment I just ran, I think it's not really likely to be a big deal:\\nthere are not that many problems, and most of them just amount to\\nback-patching something that originally wasn't back-patched.\\n\\nWhat's most likely to happen IMO is that committers will just start\\nback-patching essential portability fixes into out-of-support-but-\\nstill-in-the-buildability-window branches, contemporaneously with\\nthe original fix. Yeah, that does mean more committer effort,\\nbut only for a very small number of patches.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Fri, 03 Dec 2021 13:30:31 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 3, 2021 at 1:30 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> What's most likely to happen IMO is that committers will just start\\n> back-patching essential portability fixes into out-of-support-but-\\n> still-in-the-buildability-window branches, contemporaneously with\\n> the original fix. Yeah, that does mean more committer effort,\\n> but only for a very small number of patches.\\n\\nI agree. I think that's exactly what we want to have happen, and if a\\ngiven policy won't have exactly this result then the policy needs\\nadjusting.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 3 Dec 2021 15:46:04 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"I ran a new set of experiments concerning building back branches\\non modern platforms, this time trying Fedora 35 (gcc 11.2.1)\\non x86_64. I widened the scope of the testing a bit by adding\\n\\\"--enable-nls --with-perl\\\" and running check-world not just the\\ncore tests. Salient results:\\n\\n* Everything back to 9.2 passes the test, although with more\\nand more compile warnings the further back you go.\\n\\n* 9.1 fails with \\\"conflicting types for 'base_yylex'\\\", much as\\nI saw on macOS except it's a hard error on this compiler.\\n\\n* Parallel check-world is pretty unreliable before v10 (I knew\\nthis already, actually). But without parallelism, it's fine.\\n\\nBased on these results, I think maybe we should raise our ambitions\\na bit compared to Peter's original proposal. Specifically,\\nI wonder if it wouldn't be wise to try to silence compile warnings\\nin these branches. The argument for this is basically that if we\\ndon't, then every time someone builds one of these branches, they\\nhave to tediously go through the warnings and verify that\\nthey're not important. It won't take long for the accumulated\\ntime-wastage from that to exceed the cost of back-patching whatever\\nwe did to silence the warning in later branches.\\n\\nNow, I'm still not interested in trying to silence\\nmaybe-uninitialized warnings pre-9.3, mainly because of the\\nereport-ERROR-doesnt-return issue. (I saw far fewer of those\\nunder gcc than clang, but not zero.) We could ignore those\\nfiguring that 9.2 will be out of scope in a year anyway, or else\\nteach 9.2's configure to select -Wno-maybe-uninitialized where\\npossible.\\n\\nLikewise, getting check-world to parallelize successfully pre-v10\\nseems like a bridge too far. But I would, for example, be in favor\\nof back-patching eb9812f27 (Make pg_upgrade's test.sh less chatty).\\nIt's just annoying to run check-world and get that output now.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 05 Dec 2021 19:41:14 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Sun, Dec 5, 2021 at 7:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Based on these results, I think maybe we should raise our ambitions\\n> a bit compared to Peter's original proposal. Specifically,\\n> I wonder if it wouldn't be wise to try to silence compile warnings\\n> in these branches. The argument for this is basically that if we\\n> don't, then every time someone builds one of these branches, they\\n> have to tediously go through the warnings and verify that\\n> they're not important. It won't take long for the accumulated\\n> time-wastage from that to exceed the cost of back-patching whatever\\n> we did to silence the warning in later branches.\\n\\nYep. I have long been of the view, and have said before, that there is\\nvery little harm in doing some maintenance of EOL branches. Making it\\neasy to test against them is a great way to improve our chances of\\nactually having the amount of backward-compatibility that we say we\\nwant to have.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 6 Dec 2021 15:38:55 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Sun, Dec 5, 2021 at 7:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Based on these results, I think maybe we should raise our ambitions\\n>> a bit compared to Peter's original proposal. Specifically,\\n>> I wonder if it wouldn't be wise to try to silence compile warnings\\n>> in these branches.\\n\\n> Yep. I have long been of the view, and have said before, that there is\\n> very little harm in doing some maintenance of EOL branches. Making it\\n> easy to test against them is a great way to improve our chances of\\n> actually having the amount of backward-compatibility that we say we\\n> want to have.\\n\\nRight. The question that's on the table is how much is the right\\namount of maintenance. I think that back-patching user-visible bug\\nfixes, for example, is taking things too far. What we want is to\\nbe able to replicate the behavior of the branch's last released\\nversion, using whatever build tools we are currently using. So\\nback-patching something like that is counterproductive, because\\nnow the behavior is not what was released.\\n\\nA minimal amount of maintenance would be \\\"only back-patch fixes\\nfor issues that cause failure-to-build\\\". The next step up is \\\"fix\\nissues that cause failure-to-pass-regression-tests\\\", and then above\\nthat is \\\"fix developer-facing annoyances, such as compiler warnings\\nor unwanted test output, as long as you aren't changing user-facing\\nbehavior\\\". I now think that it'd be reasonable to include this\\nlast group, although I'm pretty sure Peter didn't have that in mind\\nin his policy sketch.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 06 Dec 2021 16:19:08 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 6, 2021 at 4:19 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Right. The question that's on the table is how much is the right\\n> amount of maintenance. I think that back-patching user-visible bug\\n> fixes, for example, is taking things too far. What we want is to\\n> be able to replicate the behavior of the branch's last released\\n> version, using whatever build tools we are currently using. So\\n> back-patching something like that is counterproductive, because\\n> now the behavior is not what was released.\\n>\\n> A minimal amount of maintenance would be \\\"only back-patch fixes\\n> for issues that cause failure-to-build\\\". The next step up is \\\"fix\\n> issues that cause failure-to-pass-regression-tests\\\", and then above\\n> that is \\\"fix developer-facing annoyances, such as compiler warnings\\n> or unwanted test output, as long as you aren't changing user-facing\\n> behavior\\\". I now think that it'd be reasonable to include this\\n> last group, although I'm pretty sure Peter didn't have that in mind\\n> in his policy sketch.\\n\\nYep, that seems reasonable to me.\\n\\nI guess the point about user-visible bug fixes is that, as soon as we\\nstart doing that, we don't really want it to be hit-or-miss. We could\\nmake a decision to back-patch all bug fixes or those of a certain\\nseverity or whatever we like back to older branches, and then those\\nbranches would be supported or semi-supported depending on what rule\\nwe adopted, and we could even continue to do releases for them if we\\nso chose. However, it wouldn't be a great idea to back-patch a\\ncompletely arbitrary subset of our fixes into those branches, because\\nthen it sort of gets confusing to understand what the status of that\\nbranch is. I don't know that I'm terribly bothered by the idea that\\nthe behavior of the branch might deviate from the last official\\nrelease, because most bug fixes are pretty minor and wouldn't really\\naffect testing much, but it would be a little annoying to explain to\\nusers that those branches contain an arbitrary subset of newer fixes,\\nand a little hard for us to understand what is and is not there.\\n\\nThat being said, suppose that a new compiler version comes out and on\\nthat new compiler version, 'make check' crashes on the older branch\\ndue to a missing WhateverGetDatum() call that we rectified in a later,\\nback-patched commit. I would consider it reasonable to back-patch that\\nparticular bug fix into an unsupported branch to make it testable,\\njust like we would do for a failure-to-build issue.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 11:33:38 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> I guess the point about user-visible bug fixes is that, as soon as we\\n> start doing that, we don't really want it to be hit-or-miss. We could\\n> make a decision to back-patch all bug fixes or those of a certain\\n> severity or whatever we like back to older branches, and then those\\n> branches would be supported or semi-supported depending on what rule\\n> we adopted, and we could even continue to do releases for them if we\\n> so chose. However, it wouldn't be a great idea to back-patch a\\n> completely arbitrary subset of our fixes into those branches, because\\n> then it sort of gets confusing to understand what the status of that\\n> branch is.\\n\\nYup, and also confusing to understand whether a given new fix should\\nbe back-patched into the out-of-support-but-keep-buildable branches.\\nI want to settle on a reasonably well-defined policy for that.\\n\\nI'm basically suggesting that the policy should be \\\"back-patch the\\nminimal fix needed so that you can still get a clean build and clean\\ncheck-world run, using thus-and-such configure options\\\". (The point\\nof the configure options limitation being to exclude moving-target\\nexternal dependencies, such as Python.) I think that Peter's\\noriginal suggestion could be read the same way except for the\\nadjective \\\"clean\\\". He also said that only core regression needs\\nto pass not check-world; but if we're trying to test things like\\npg_dump compatibility, I think we want the wider scope of what to\\nkeep working.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 07 Dec 2021 12:46:09 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 7, 2021, at 8:33 AM, Robert Haas <robertmhaas@gmail.com> wrote:\\n> \\n> However, it wouldn't be a great idea to back-patch a\\n> completely arbitrary subset of our fixes into those branches, because\\n> then it sort of gets confusing to understand what the status of that\\n> branch is. I don't know that I'm terribly bothered by the idea that\\n> the behavior of the branch might deviate from the last official\\n> release, because most bug fixes are pretty minor and wouldn't really\\n> affect testing much, but it would be a little annoying to explain to\\n> users that those branches contain an arbitrary subset of newer fixes,\\n> and a little hard for us to understand what is and is not there.\\n\\nWouldn't you be able to see what changed by comparing the last released tag for version X.Y against the RELX_Y_STABLE branch? Something like `git diff REL8_4_22 origin/REL8_4_STABLE > buildability.patch`?\\n\\nHaving such a patch should make reproducing old corruption bugs easier, as you could apply the buildability.patch to the last branch that contained the bug. If anybody did that work, would we want it committed somewhere? REL8_4_19_BUILDABLE or such? For patches that apply trivially, that might not be worth keeping, but if the merge is difficult, maybe sharing with the community would make sense.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 10:26:13 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Mark Dilger <mark.dilger@enterprisedb.com> writes:\\n> Wouldn't you be able to see what changed by comparing the last released tag for version X.Y against the RELX_Y_STABLE branch? Something like `git diff REL8_4_22 origin/REL8_4_STABLE > buildability.patch`?\\n\\n> Having such a patch should make reproducing old corruption bugs easier, as you could apply the buildability.patch to the last branch that contained the bug. If anybody did that work, would we want it committed somewhere? REL8_4_19_BUILDABLE or such? For patches that apply trivially, that might not be worth keeping, but if the merge is difficult, maybe sharing with the community would make sense.\\n\\nI'm not entirely following ... are you suggesting that each released minor\\nversion needs to be kept buildable separately? That seems like a huge\\namount of extra committer effort with not much added value. If someone\\ncomes to me and wants to investigate a bug in a branch that's already\\nout-of-support, and they then say they're not running the last minor\\nrelease, I'm going to tell them to come back after updating.\\n\\nIt is (I suspect) true that diffing the last release against branch\\ntip would often yield a patch that could be used to make an older\\nminor release buildable again. But when that patch doesn't work\\ntrivially, I for one am not interested in making it work. And\\nespecially not interested in doing so \\\"on spec\\\", with no certainty\\nthat anyone would ever need it.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 07 Dec 2021 13:52:34 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Dec 7, 2021, at 10:52 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> \\n> I'm not entirely following ... are you suggesting that each released minor\\n> version needs to be kept buildable separately?\\n\\nNo. I'm just wondering if we want to share the product of such efforts if anybody (me, for instance) volunteers to do it for some subset of minor releases. For my heap corruption checking work, I might want to be able to build a small number of old minor releases that I know had corruption bugs.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 10:59:02 -0800\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 12/7/21 13:59, Mark Dilger wrote:\\n>> On Dec 7, 2021, at 10:52 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>>\\n>> I'm not entirely following ... are you suggesting that each released minor\\n>> version needs to be kept buildable separately?\\n> No. I'm just wondering if we want to share the product of such efforts if anybody (me, for instance) volunteers to do it for some subset of minor releases. For my heap corruption checking work, I might want to be able to build a small number of old minor releases that I know had corruption bugs.\\n>\\n\\nI doubt there's going to be a whole lot of changes. You should just be\\nable to cherry-pick them in most cases I suspect.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 7 Dec 2021 14:19:36 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On 06.12.21 22:19, Tom Lane wrote:\\n> A minimal amount of maintenance would be \\\"only back-patch fixes\\n> for issues that cause failure-to-build\\\". The next step up is \\\"fix\\n> issues that cause failure-to-pass-regression-tests\\\", and then above\\n> that is \\\"fix developer-facing annoyances, such as compiler warnings\\n> or unwanted test output, as long as you aren't changing user-facing\\n> behavior\\\". I now think that it'd be reasonable to include this\\n> last group, although I'm pretty sure Peter didn't have that in mind\\n> in his policy sketch.\\n\\nI would be okay with that.\\n\\n\\n\",\n \"msg_date\": \"Thu, 9 Dec 2021 15:01:43 +0100\",\n \"msg_from\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"[ mostly for the archives' sake ]\\n\\nI wrote:\\n> I ran a new set of experiments concerning building back branches\\n> on modern platforms, this time trying Fedora 35 (gcc 11.2.1)\\n> on x86_64. I widened the scope of the testing a bit by adding\\n> \\\"--enable-nls --with-perl\\\" and running check-world not just the\\n> core tests. Salient results:\\n\\n> * 9.1 fails with \\\"conflicting types for 'base_yylex'\\\", much as\\n> I saw on macOS except it's a hard error on this compiler.\\n\\nI poked a little harder at what might be needed to get 9.1 compiled\\non modern platforms. It looks like the base_yylex issue is down\\nto newer versions of flex doing things differently. We fixed\\nthat in the v10 era via 72b1e3a21 (Build backend/parser/scan.l and\\ninterfaces/ecpg/preproc/pgc.l standalone) and 92fb64983 (Use \\\"%option\\nprefix\\\" to set API names in ecpg's lexer), which were later back-patched\\nas far down as 9.2. It might not be out of the question to back-patch\\nthose further, but the 9.2 patches don't apply cleanly to 9.1, so some\\neffort would be needed.\\n\\nWorrisomely, I also noted warnings like\\n\\nparse_coerce.c:791:67: warning: array subscript 1 is above array bounds of 'Oid[1]' {aka 'unsigned int[1]'} [-Warray-bounds]\\n 791 | Assert(nargs < 2 || procstruct->proargtypes.values[1] == INT4OID);\\n | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~\\n\\nwhich remind me that 9.1 lacks 8137f2c32 (Hide most variable-length fields\\nfrom Form_pg_* structs). We did stick -fno-aggressive-loop-optimizations\\ninto 9.1 and older branches back in 2015, but I don't have a lot of\\nconfidence that that'd be sufficient to prevent misoptimizations in\\ncurrent-vintage compilers. Back-patching 8137f2c32 and all the follow-on\\nwork is very clearly not something to consider, so dialing down the -O\\nlevel might be necessary if you were interested in making this go.\\n\\nIn short then, there is a really large gap between 9.1 and 9.2 in terms\\nof how hard they are to build on current toolchains. It's kind of\\nfortunate that Peter proposed 9.2 rather than some earlier cutoff.\\nIn any case, I've completely lost interest in trying to move the\\nkeep-it-buildable cutoff to any earlier than 9.2; it doesn't look\\nlike the effort-to-benefit ratio would be attractive at all.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 09 Dec 2021 12:50:40 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"\\nOn 12/9/21 12:50, Tom Lane wrote:\\n>\\n> In short then, there is a really large gap between 9.1 and 9.2 in terms\\n> of how hard they are to build on current toolchains. It's kind of\\n> fortunate that Peter proposed 9.2 rather than some earlier cutoff.\\n> In any case, I've completely lost interest in trying to move the\\n> keep-it-buildable cutoff to any earlier than 9.2; it doesn't look\\n> like the effort-to-benefit ratio would be attractive at all.\\n>\\n> \\t\\t\\t\\n\\n\\n9.2 is how far back crake goes in testing pg_ugrade from old versions,\\nso that could well be a convenient stopping point. For older versions\\nthere is still the possibility of building on older toolchains and\\nrunning on modern ones. Yes it's more cumbersome, but it does mean we\\ncan test an awful long way back. I don't remember the last time I saw a\\nreally old version in the wild, but I'm sure there are some out there\\nsitting in a cupboard humming along.\\n\\nThis might also be a good time to revive work on making the TAP test\\nframework backwards compatible via subclassing.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Sat, 11 Dec 2021 10:17:17 -0500\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Andrew Dunstan <andrew@dunslane.net> writes:\\n> 9.2 is how far back crake goes in testing pg_ugrade from old versions,\\n> so that could well be a convenient stopping point. For older versions\\n> there is still the possibility of building on older toolchains and\\n> running on modern ones. Yes it's more cumbersome, but it does mean we\\n> can test an awful long way back.\\n\\nRight. I think the point of the current discussion is to ensure that,\\nif we expect new patches for pg_dump or psql to work against version-N\\nservers, that it's not too unpleasant for patch submitters to build\\nand test against version N. There's a different discussion to be had\\nabout what we do if we receive a bug report about compatibility with\\nsome more-ancient-than-that version. But that is, I hope, a far less\\ncommon scenario; so it's okay if it requires extra effort, and/or use\\nof setups that not everyone has handy.\\n\\nAnyway, it seems like there's some consensus that 9.2 is a good\\nstopping place for today. I'll push forward with\\n(1) back-patching as necessary to make 9.2 and up build cleanly\\non the platforms I have handy;\\n(2) ripping out pg_dump's support for pre-9.2 servers;\\n(3) ripping out psql's support for pre-9.2 servers.\\n\\nIn a preliminary look, it did not seem that (3) would save very\\nmuch code, but it seems like we ought to do it if we're being\\nconsistent.\\n\\nA point we've not discussed is whether to drop any bits of libpq\\nthat are only needed for such old servers. I feel a bit more\\nuncomfortable about that, mainly because I'm pretty sure that\\nonly a few lines of code would be involved, and it seems to have\\nmore of an air of burning-the-bridges finality about it than (say)\\ndropping psql/describe.c support. On the other hand, the point\\nabout what's required to test future patches still applies.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 12 Dec 2021 01:24:24 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"I wrote:\\n> Anyway, it seems like there's some consensus that 9.2 is a good\\n> stopping place for today. I'll push forward with\\n> (1) back-patching as necessary to make 9.2 and up build cleanly\\n> on the platforms I have handy;\\n\\nI've done as much as I plan to do in that direction. As of the\\nrespective branch tips, I see clean builds and check-world\\nresults with minimal configure options in all branches back to 9.2\\non Fedora 35 (gcc 11.2.1) and macOS Monterey (Apple clang 13.0.0).\\n\\nA few notes for the archives' sake:\\n\\n* As discussed, parallel check-world is unreliable before v10;\\nperhaps this is worth improving, but I doubt it. I did find\\nthat aggressive parallelism in the build process is fine.\\n\\n* On some compilers, pre-v10 branches produce this warning:\\n\\nscan.c: In function 'yy_try_NUL_trans':\\nscan.c:10189:23: warning: unused variable 'yyg' [-Wunused-variable]\\n struct yyguts_t * yyg = (struct yyguts_t*)yyscanner; /* This var may be unused depending upon options. */\\n\\nIn principle we could back-patch 65d508fd4 to silence that,\\nbut I think that fix is more invasive than what we want to\\ndo in these branches. We lived with that warning for years\\nbefore figuring out how to get rid of it, so I think we can\\ncontinue to accept it in these branches.\\n\\n* 9.2's plperl fails to compile on macOS:\\n\\n./plperl.h:53:10: fatal error: 'EXTERN.h' file not found\\n#include \\\"EXTERN.h\\\"\\n\\nThis is evidently because 9.2 predates the \\\"sysroot\\\" hacking\\nwe did later (5e2217131 and many many subsequent tweaks).\\nI judge this not worth the trouble to fix, because the argument\\nfor supporting --with-perl in these branches is basically that\\nwe need a PL with transforms to test pg_dump ... but transforms\\ndidn't come in until 9.5. (Reviewing the commit log, I suppose\\nthat 9.3 and 9.4 would also fail to build in some macOS\\nconfigurations, but by the same argument I see no need to work\\nfurther on those branches either. 9.5 does have all the\\nsysroot changes I can find in the log.)\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 13 Dec 2021 12:23:10 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 13, 2021 at 12:23 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> I've done as much as I plan to do in that direction. As of the\\n> respective branch tips, I see clean builds and check-world\\n> results with minimal configure options in all branches back to 9.2\\n> on Fedora 35 (gcc 11.2.1) and macOS Monterey (Apple clang 13.0.0).\\n\\nI think this is great. Thanks for being willing to work on it.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 13 Dec 2021 12:33:50 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"I wrote:\\n> Anyway, it seems like there's some consensus that 9.2 is a good\\n> stopping place for today. I'll push forward with\\n> (1) back-patching as necessary to make 9.2 and up build cleanly\\n> on the platforms I have handy;\\n> (2) ripping out pg_dump's support for pre-9.2 servers;\\n> (3) ripping out psql's support for pre-9.2 servers.\\n\\nI've completed the pg_dump/pg_dumpall part of that, but while\\nupdating the docs I started to wonder whether we shouldn't nuke\\npg_dump's --no-synchronized-snapshots option. As far as I can\\nmake out, the remaining use case for that is to let you perform an\\nunsafe parallel dump from a standby server of an out-of-support\\nmajor version. I'm not very clear why we allowed that at all,\\never, rather than saying you can't parallelize in such cases.\\nBut for sure that remaining use case is paper thin, and leaving\\nthe option available seems way more likely to let people shoot\\nthemselves in the foot than to let them do anything helpful.\\n\\nBarring objections, I'll remove that option in a day or two.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 14 Dec 2021 17:18:44 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 14, 2021 at 05:18:44PM -0500, Tom Lane wrote:\\n> I wrote:\\n> > Anyway, it seems like there's some consensus that 9.2 is a good\\n> > stopping place for today. I'll push forward with\\n> > (1) back-patching as necessary to make 9.2 and up build cleanly\\n> > on the platforms I have handy;\\n> > (2) ripping out pg_dump's support for pre-9.2 servers;\\n> > (3) ripping out psql's support for pre-9.2 servers.\\n> \\n> I've completed the pg_dump/pg_dumpall part of that, but while\\n\\nIs it possible to clean up pg_upgrade, too ?\\n\\n-- \\nJustin\\n\\n\\n\",\n \"msg_date\": \"Wed, 15 Dec 2021 22:08:07 -0600\",\n \"msg_from\": \"Justin Pryzby <pryzby@telsasoft.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Justin Pryzby <pryzby@telsasoft.com> writes:\\n> On Tue, Dec 14, 2021 at 05:18:44PM -0500, Tom Lane wrote:\\n>> I've completed the pg_dump/pg_dumpall part of that, but while\\n\\n> Is it possible to clean up pg_upgrade, too ?\\n\\nhttps://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=e469f0aaf3c586c8390bd65923f97d4b1683cd9f\\n\\nI'm still working on psql.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 15 Dec 2021 23:55:41 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 15, 2021 at 10:08:07PM -0600, Justin Pryzby wrote:\\n> Is it possible to clean up pg_upgrade, too ?\\n\\nNevermind - I found yesterday's e469f0aaf3 after git-fetch.\\n\\nI think you missed a few parts though ?\\n\\nsrc/bin/pg_upgrade/function.c\\n if (GET_MAJOR_VERSION(old_cluster.major_version) <= 900)\\n...\\n if (GET_MAJOR_VERSION(old_cluster.major_version) <= 900 &&\\n strcmp(lib, \\\"$libdir/plpython\\\") == 0)\\n\\nsrc/bin/pg_upgrade/option.c\\n * Someday, the port number option could be removed and passed\\n * using -o/-O, but that requires postmaster -C to be\\n * supported on all old/new versions (added in PG 9.2).\\n...\\n if (GET_MAJOR_VERSION(cluster->major_version) >= 901)\\n\\n\\n\",\n \"msg_date\": \"Wed, 15 Dec 2021 22:58:04 -0600\",\n \"msg_from\": \"Justin Pryzby <pryzby@telsasoft.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"Justin Pryzby <pryzby@telsasoft.com> writes:\\n> I think you missed a few parts though ?\\n\\nUm. I think those are leftover from when I was intending the\\ncutoff to be 9.0 not 9.2. I'll take a fresh look tomorrow.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 16 Dec 2021 00:02:54 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n },\n {\n \"msg_contents\": \"On Fri, 22 Oct 2021 at 19:27, Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> Another thing to think about in that regard: how likely is that\\n> PostgreSQL 7.4 and PostgreSQL 15 both compile and run on the same\\n> operating system? I suspect the answer is \\\"not very.\\\" I seem to recall\\n> Greg Stark trying to compile really old versions of PostgreSQL for a\\n> conference talk some years ago, and he got back to a point where it\\n> just became impossible to make work on modern toolchains even with a\\n> decent amount of hackery.\\n\\nThat was when I compared sorting performance over time. I was able to\\nget Postgres to build back to the point where 64-bit architecture\\nsupport was added. From Andrew Dunstans comment later in this thread\\nI'm guessing that was 7.2\\n\\nThat was basically at the point where 64-bit architecture support was\\nadded. It looks like the earliest date on the graphs in the talk are\\n2002-11-27 which matches the 7.3 release date. I think building\\nearlier versions would have been doable if I had built them in 32-bit\\nmode.\\n\\n-- \\ngreg\\n\\n\\n\",\n \"msg_date\": \"Fri, 17 Dec 2021 03:06:50 -0500\",\n \"msg_from\": \"Greg Stark <stark@mit.edu>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pg_dump versus ancient server versions\"\n }\n]","isConversational":false}}},{"rowIdx":52987,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Simple patch to implement $SUBJECT attached.\n\npg_signal_backend seems like the appropriate predefined role, because\npg_log_backend_memory_contexts() is implemented by a sending signal.\n\nRegards,\n\tJeff Davis","msg_date":"Sat, 23 Oct 2021 12:57:02 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On 10/23/21, 12:57 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> pg_signal_backend seems like the appropriate predefined role, because\r\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\r\n\r\nThis seems reasonable to me. The stated reason in the original commit\r\nmessage for keeping it restricted to superusers is because of the\r\ndenial-of-service risk, but if you've got pg_signal_backend, you can\r\nalready terminate sessions. The predefined roles documentation notes\r\nthat members of pg_signal_backend cannot signal superuser-owned\r\nbackends, but AFAICT pg_log_backend_memory_contexts() has no such\r\nrestriction at the moment. Should we add this?\r\n\r\nOtherwise, presumably we will need to update func.sgml and the comment\r\nabove pg_log_backend_memory_contexts() in mcxtfuncs.c.\r\n\r\nThis is unrelated to this patch, but should we also consider opening\r\nup pg_reload_conf() and pg_rotate_logfile() to members of\r\npg_signal_backend? Those are the other \"server signaling functions\" I\r\nsee in the docs.\r\n\r\nNathan\r\n\r\n","msg_date":"Sat, 23 Oct 2021 20:42:29 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sat, Oct 23, 2021 at 08:42:29PM +0000, Bossart, Nathan wrote:\n> Otherwise, presumably we will need to update func.sgml and the comment\n> above pg_log_backend_memory_contexts() in mcxtfuncs.c.\n\nYes, the documentation of any SQL function whose hardcoded superuser()\ncheck is removed needs a refresh to outline that its execution can be\nGRANT-ed post-initialization, and it should also document which system\nroles are able to use it. See for instance pg_database_size(), that\nmentions roles need to be a member of pg_read_all_stats.\n\n> This is unrelated to this patch, but should we also consider opening\n> up pg_reload_conf() and pg_rotate_logfile() to members of\n> pg_signal_backend? Those are the other \"server signaling functions\" I\n> see in the docs.\n\nYes, there is that as well.\n\n+CREATE ROLE testrole1 IN ROLE pg_signal_backend;\n+CREATE ROLE testrole2;\nAny role created in the regression test needs to be prefixed with\n\"regress_\", or builds with -DENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS\nwill complain (I just add that by default to not fall into this trap\nagain).\n--\nMichael","msg_date":"Sun, 24 Oct 2021 08:41:52 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sun, Oct 24, 2021 at 1:27 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n>\n> Simple patch to implement $SUBJECT attached.\n>\n> pg_signal_backend seems like the appropriate predefined role, because\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\n\n+1.\n\nIt looks like we are better off with removing explicit superuser()\nchecks from the functions and using normal GRANT based system, see\nothers agreeing on this at [1]. As we have lots of functions that are\ndoing explicit superuser() checks, I'm sure someday they all will have\nto be moved to GRANT system. The current code is a mix - some\nfunctions do explicit checks (I've seen many of them with the comment\nat [2]) and others do it via GRANT system. I'm not saying that we\nshould be dealing with those here in this thread, all I'm looking for\nis that we have a note of it in the postgres todo list in the wiki so\nthat someone interested can pick that work up. Thoughts?\n\nComments on the patch:\n1) testrole1 and testrole2 look generic, how about\nregress_mcxt_role1/2? There's no problem as they are\nmisc_functions.sql local, but still role names can be more readable.\n+CREATE ROLE testrole1 IN ROLE pg_signal_backend;\n+CREATE ROLE testrole2;\n2) It seems like the privileges.sql is the right place to place the\ntest cases, but I'm fine with keeping all the test cases of the\nfunction together.\n3) It might be enough to do has_function_privilege, just a thought -\nisn't it better if we execute the function with the test roles set in.\nThis will help us catch the permission denied error message in the\ntest output files.\n4) Isn't the +#define CATALOG_VERSION_NO 202110230 going to be set to\nthe date on which the patch gets committed?\n5) The following change is being handled in the patch at [3], I know\nit is appropriate to have it in this patch, but please mention it in\nthe commit message on why we do this change. I will remove this change\nfrom my patch at [3].\n-SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\n+SELECT pg_log_backend_memory_contexts(pg_backend_pid());\n\n[1] - https://www.postgresql.org/message-id/CAOuzzgpp0dmOFjWC4JDvk57ZQGm8umCrFdR1at4b80xuF0XChw%40mail.gmail.com\n[2] -\n * Permission checking for this function is managed through the normal\n * GRANT system.\n */\n[3] - https://www.postgresql.org/message-id/CALj2ACVXk1roswqFpiCOMHrsB%2BxxW7HG536krGAzF%3DmWXh3eWQ%40mail.gmail.com\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Sun, 24 Oct 2021 19:58:16 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\n> The predefined roles documentation notes\n> that members of pg_signal_backend cannot signal superuser-owned\n> backends, but AFAICT pg_log_backend_memory_contexts() has no such\n> restriction at the moment. Should we add this?\n\nAdded, good catch.\n\n> This is unrelated to this patch, but should we also consider opening\n> up pg_reload_conf() and pg_rotate_logfile() to members of\n> pg_signal_backend? Those are the other \"server signaling functions\"\n> I\n> see in the docs.\n\nThose are actually signalling the postmaster, not an ordinary backend.\nAlso, those functions are already GRANTable, so I think we should leave\nthem as-is.\n\nRegards,\n\tJeff Davis","msg_date":"Sun, 24 Oct 2021 09:50:58 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sun, 2021-10-24 at 19:58 +0530, Bharath Rupireddy wrote:\n> It looks like we are better off with removing explicit superuser()\n> checks from the functions and using normal GRANT based system, see\n> others agreeing on this at [1]. As we have lots of functions that are\n> doing explicit superuser() checks, I'm sure someday they all will\n> have\n> to be moved to GRANT system.\n\nNote that some functions have additional checks that can't be expressed\nwith GRANT -- see pg_cancel_backend(), for example. But I agree in\ngeneral that GRANT is the way to go most of the time.\n\n> The current code is a mix - some\n> functions do explicit checks (I've seen many of them with the comment\n> at [2]) and others do it via GRANT system. I'm not saying that we\n> should be dealing with those here in this thread, all I'm looking for\n> is that we have a note of it in the postgres todo list in the wiki so\n> that someone interested can pick that work up. Thoughts?\n\nIt seems like there's agreement on the direction, but I don't know that\nthere's a good place to write it down. Probably better to just fix as\nmany of the functions as we can, and then when people add new ones,\nthey'll copy the GRANT pattern rather than the explicit superuser\ncheck.\n\n> Comments on the patch:\n> 1) testrole1 and testrole2 look generic, how about\n\nMichael had a similar comment. Renamed, thank you.\n\n> 2) It seems like the privileges.sql is the right place to place the\n> test cases, but I'm fine with keeping all the test cases of the\n> function together.\n\nIf we add all the function privilege checks there, I think it will\noverwhelm the other interesting tests happening in that file.\n\n> 3) It might be enough to do has_function_privilege, just a thought -\n> isn't it better if we execute the function with the test roles set\n> in.\n> This will help us catch the permission denied error message in the\n> test output files.\n\nMissed this comment. I'll tweak this before commit.\n\n> 4) Isn't the +#define CATALOG_VERSION_NO 202110230 going to be set to\n> the date on which the patch gets committed?\n\nI just put it in there so that I wouldn't forget, but I'll update it at\ncommit time.\n\n> 5) The following change is being handled in the patch at [3], I know\n> it is appropriate to have it in this patch, but please mention it in\n> the commit message on why we do this change. I will remove this\n> change\n> from my patch at [3].\n> -SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\n> +SELECT pg_log_backend_memory_contexts(pg_backend_pid());\n\nWhat would you like me to mention?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sun, 24 Oct 2021 10:04:48 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On 10/24/21, 9:51 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\r\n>> The predefined roles documentation notes\r\n>> that members of pg_signal_backend cannot signal superuser-owned\r\n>> backends, but AFAICT pg_log_backend_memory_contexts() has no such\r\n>> restriction at the moment. Should we add this?\r\n>\r\n> Added, good catch.\r\n\r\nThe new patch looks good to me.\r\n\r\nNathan\r\n\r\n","msg_date":"Sun, 24 Oct 2021 20:59:48 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"At Sun, 24 Oct 2021 09:50:58 -0700, Jeff Davis <pgsql@j-davis.com> wrote in \n> On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\n> > The predefined roles documentation notes\n> > that members of pg_signal_backend cannot signal superuser-owned\n> > backends, but AFAICT pg_log_backend_memory_contexts() has no such\n> > restriction at the moment. Should we add this?\n> \n> Added, good catch.\n> \n> > This is unrelated to this patch, but should we also consider opening\n> > up pg_reload_conf() and pg_rotate_logfile() to members of\n> > pg_signal_backend? Those are the other \"server signaling functions\"\n> > I\n> > see in the docs.\n> \n> Those are actually signalling the postmaster, not an ordinary backend.\n> Also, those functions are already GRANTable, so I think we should leave\n> them as-is.\n\nI'm afraid that it might be wrong that all backend-signalling features\nare allowed by that priviledge. pg_signal_backends is described in\nthe doc as:\n\nhttps://www.postgresql.org/docs/devel/predefined-roles.html\n\n> Signal another backend to cancel a query or terminate its session.\n\nHere, the term \"signal\" there seems to mean interrupting something on\nthat session or the session itself. Addition to that I don't think\n\"terminate a session or the query on a session\" and \"log something on\nanother session\" and \"rotate log file\" don't fall into the same\ncategory in a severity view.\n\nIn other words, I don't think pg_signal_backends is not meant to\ncontrol \"log something on another session\" or \"rotate log file\". It's\ndanger that if we allow somewone to rotate log files, that means to\nallow same user to terminate another session.\n\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Mon, 25 Oct 2021 11:53:33 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Mon, 2021-10-25 at 11:53 +0900, Kyotaro Horiguchi wrote:\n> In other words, I don't think pg_signal_backends is not meant to\n> control \"log something on another session\" or \"rotate log file\". \n> It's\n> danger that if we allow somewone to rotate log files, that means to\n> allow same user to terminate another session.\n\nThe current patch doesn't allow members of pg_signal_backend to rotate\nthe log file.\n\nDo you think pg_signal_backend is the wrong group to allow usage of\npg_log_backend_memory_contexts()? Alternatively, it could simply not\nGRANT anything, and leave that up to the administrator to choose who\ncan use it.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sun, 24 Oct 2021 20:31:37 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"At Sun, 24 Oct 2021 20:31:37 -0700, Jeff Davis <pgsql@j-davis.com> wrote in \n> On Mon, 2021-10-25 at 11:53 +0900, Kyotaro Horiguchi wrote:\n> > In other words, I don't think pg_signal_backends is not meant to\n> > control \"log something on another session\" or \"rotate log file\". \n> > It's\n> > danger that if we allow somewone to rotate log files, that means to\n> > allow same user to terminate another session.\n> \n> The current patch doesn't allow members of pg_signal_backend to rotate\n> the log file.\n\nAh, sorry, I might have confused with some other discussion.\n\n> Do you think pg_signal_backend is the wrong group to allow usage of\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\n\nYes. I think it would be danger that who is allowed to dump memory\ncontext into log files by granting pg_signal_backend also can\nterminate other backends.\n\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\n> GRANT anything, and leave that up to the administrator to choose who\n> can use it.\n\n*I* prefer that. I'm not sure I'm the only one to think so, though..\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Mon, 25 Oct 2021 13:13:43 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Mon, Oct 25, 2021 at 9:43 AM Kyotaro Horiguchi\n<horikyota.ntt@gmail.com> wrote:\n> > Do you think pg_signal_backend is the wrong group to allow usage of\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\n>\n> Yes. I think it would be danger that who is allowed to dump memory\n> context into log files by granting pg_signal_backend also can\n> terminate other backends.\n>\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\n> > GRANT anything, and leave that up to the administrator to choose who\n> > can use it.\n>\n> *I* prefer that. I'm not sure I'm the only one to think so, though..\n\nHow about we have a separate predefined role for the functions that\ndeal with server logs? I'm not sure if Mark Dilger's patch on new\npredefined roles has one, if not, how about something like\npg_write_server_log/pg_manage_server_log/some other name?\n\nIf not with a new predefined role, how about expanding the scope of\nexisting pg_write_server_files role?\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Mon, 25 Oct 2021 09:57:52 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sun, Oct 24, 2021 at 08:31:37PM -0700, Jeff Davis wrote:\n> The current patch doesn't allow members of pg_signal_backend to rotate\n> the log file.\n> \n> Do you think pg_signal_backend is the wrong group to allow usage of\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\n> GRANT anything, and leave that up to the administrator to choose who\n> can use it.\n\nHmm. Why don't you split the patch into two parts that can be\ndiscussed separately then? There would be one to remove all the\nsuperuser() checks you can think of, and a potential second to grant \nthose function's execution to some system role.\n\nFWIW, if the barrier between a role and a function is thin, perhaps\nwe'd better just limit ourselves to the removal of the superuser()\nchecks for now rather than trying to plug more groups into the\nfunctions. When I have dealt with such issues in the past, I tend to\njust do the superuser()/REVOKE part without more GRANTs or even more\nsystem roles, as this is enough to give room to users to do what they\nwant with their clusters. And this is a no-brainer.\n--\nMichael","msg_date":"Mon, 25 Oct 2021 16:10:15 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Sun, Oct 24, 2021 at 10:34 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > 5) The following change is being handled in the patch at [3], I know\n> > it is appropriate to have it in this patch, but please mention it in\n> > the commit message on why we do this change. I will remove this\n> > change\n> > from my patch at [3].\n> > -SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\n> > +SELECT pg_log_backend_memory_contexts(pg_backend_pid());\n>\n> What would you like me to mention?\n\nSomething like below in the commit message would be good:\n\"While on this, change the way the tests use pg_log_backend_memory_contexts()\nUsually for functions, we don't use \"SELECT-FROM-<<function>>\",\nwe just use \"SELECT-<<function>>\".\"\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Mon, 25 Oct 2021 14:44:51 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Mon, Oct 25, 2021 at 12:40 PM Michael Paquier <michael@paquier.xyz> wrote:\n>\n> On Sun, Oct 24, 2021 at 08:31:37PM -0700, Jeff Davis wrote:\n> > The current patch doesn't allow members of pg_signal_backend to rotate\n> > the log file.\n> >\n> > Do you think pg_signal_backend is the wrong group to allow usage of\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\n> > GRANT anything, and leave that up to the administrator to choose who\n> > can use it.\n>\n> Hmm. Why don't you split the patch into two parts that can be\n> discussed separately then? There would be one to remove all the\n> superuser() checks you can think of, and a potential second to grant\n> those function's execution to some system role.\n\nIMO, in this thread we can focus on remvong the\npg_log_backend_memory_contexts()'s superuser() check and +1 to start a\nseparate thread to remove superuser() checks for the other functions\nand REVOKE the permissions in appropriate places, for system functins\nsystem_functions.sql files, for extension functions, the extension\ninstallation .sql files. See [1] and [2].\n\n[1] - https://www.postgresql.org/message-id/CALj2ACUhCFSUQmZhiQ%2Bw1kZdJGmhNP2cd1LZS4GVGowyjiqftQ%40mail.gmail.com\n[2] - https://www.postgresql.org/message-id/CAOuzzgpp0dmOFjWC4JDvk57ZQGm8umCrFdR1at4b80xuF0XChw%40mail.gmail.com\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Mon, 25 Oct 2021 14:49:57 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On 10/25/21, 2:21 AM, \"Bharath Rupireddy\" <bharath.rupireddyforpostgres@gmail.com> wrote:\r\n> On Mon, Oct 25, 2021 at 12:40 PM Michael Paquier <michael@paquier.xyz> wrote:\r\n>> Hmm. Why don't you split the patch into two parts that can be\r\n>> discussed separately then? There would be one to remove all the\r\n>> superuser() checks you can think of, and a potential second to grant\r\n>> those function's execution to some system role.\r\n>\r\n> IMO, in this thread we can focus on remvong the\r\n> pg_log_backend_memory_contexts()'s superuser() check and +1 to start a\r\n> separate thread to remove superuser() checks for the other functions\r\n> and REVOKE the permissions in appropriate places, for system functins\r\n> system_functions.sql files, for extension functions, the extension\r\n> installation .sql files. See [1] and [2].\r\n\r\nI like the general idea of removing hard-coded superuser checks first\r\nand granting execution to predefined roles second. I don't have any\r\nstrong opinion about what should be done in this thread and what\r\nshould be done elsewhere.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 25 Oct 2021 16:15:20 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"Hi,\n\nOn 2021-10-23 12:57:02 -0700, Jeff Davis wrote:\n> Simple patch to implement $SUBJECT attached.\n> \n> pg_signal_backend seems like the appropriate predefined role, because\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\n\nI like the idea of making pg_log_backend_memory_contexts() more widely\navailable. But I think tying it to pg_signal_backend isn't great. It's\nunnecessarily baking in an implementation detail.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 10:29:39 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\n> Hmm. Why don't you split the patch into two parts that can be\n> discussed separately then? There would be one to remove all the\n> superuser() checks you can think of, and a potential second to grant \n> those function's execution to some system role.\n\nGood idea. Attached a patch to remove the superuser check on\npg_log_backend_memory_contexts(), except in the case when trying to log\nmemory contexts of a superuser backend.\n\nUsing pg_signal_backend does not seem to be universally acceptable, so\nI'll just drop the idea of granting to that predefined role.\n\nRegards,\n\tJeff Davis","msg_date":"Mon, 25 Oct 2021 13:42:07 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On 10/25/21, 1:43 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\r\n>> Hmm. Why don't you split the patch into two parts that can be\r\n>> discussed separately then? There would be one to remove all the\r\n>> superuser() checks you can think of, and a potential second to grant\r\n>> those function's execution to some system role.\r\n>\r\n> Good idea. Attached a patch to remove the superuser check on\r\n> pg_log_backend_memory_contexts(), except in the case when trying to log\r\n> memory contexts of a superuser backend.\r\n\r\nLGTM.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 25 Oct 2021 21:26:47 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"Hi,\n\nOn 2021-10-25 13:42:07 -0700, Jeff Davis wrote:\n> Good idea. Attached a patch to remove the superuser check on\n> pg_log_backend_memory_contexts(), except in the case when trying to log\n> memory contexts of a superuser backend.\n\nI don't get the reasoning behind the \"except ...\" logic. What does this\nactually protect against? A reasonable use case for this feature is is to\nmonitor memory usage of all backends, and this restriction practially requires\nto still use a security definer function.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 25 Oct 2021 14:30:38 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Mon, 2021-10-25 at 14:30 -0700, Andres Freund wrote:\n> I don't get the reasoning behind the \"except ...\" logic. What does\n> this\n> actually protect against? A reasonable use case for this feature is\n> is to\n> monitor memory usage of all backends, and this restriction practially\n> requires\n> to still use a security definer function.\n\nNathan brought it up -- more as a question than a request, so perhaps\nit's not necessary. I don't have a strong opinion about it, but I\nincluded it to be conservative (easier to relax a privilege than to\ntighten one).\n\nI can cut out the in-function check entirely if there's no objection.\n\nRegards,\n\tJeff Davis\n\n[1] https://postgr.es/m/33F34F0C-BB16-48DE-B125-95D340A54AE8@amazon.com\n\n\n\n","msg_date":"Mon, 25 Oct 2021 16:28:13 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On 10/25/21, 4:29 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Mon, 2021-10-25 at 14:30 -0700, Andres Freund wrote:\r\n>> I don't get the reasoning behind the \"except ...\" logic. What does\r\n>> this\r\n>> actually protect against? A reasonable use case for this feature is\r\n>> is to\r\n>> monitor memory usage of all backends, and this restriction practially\r\n>> requires\r\n>> to still use a security definer function.\r\n>\r\n> Nathan brought it up -- more as a question than a request, so perhaps\r\n> it's not necessary. I don't have a strong opinion about it, but I\r\n> included it to be conservative (easier to relax a privilege than to\r\n> tighten one).\r\n\r\nI asked about it since we were going to grant execution to\r\npg_signal_backend, which (per the docs) shouldn't be able to signal a\r\nsuperuser-owned backend. I don't mind removing this now that the\r\npg_signal_backend part is removed.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 25 Oct 2021 23:58:31 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"\n\nOn 2021/10/26 5:42, Jeff Davis wrote:\n> On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\n>> Hmm. Why don't you split the patch into two parts that can be\n>> discussed separately then? There would be one to remove all the\n>> superuser() checks you can think of, and a potential second to grant\n>> those function's execution to some system role.\n> \n> Good idea. Attached a patch to remove the superuser check on\n> pg_log_backend_memory_contexts(), except in the case when trying to log\n> memory contexts of a superuser backend.\n\n- Only superusers can request to log the memory contexts.\n+ Only superusers can request to log the memory contexts of superuser\n+ backends.\n\nThe description \"This function is restricted to superusers by default,\nbut other users can be granted EXECUTE to run the function.\"\nshould be added into the docs?\n\nRegards,\n\n-- \nFujii Masao\nAdvanced Computing Technology Center\nResearch and Development Headquarters\nNTT DATA CORPORATION\n\n\n","msg_date":"Tue, 26 Oct 2021 23:32:00 +0900","msg_from":"Fujii Masao <masao.fujii@oss.nttdata.com>","msg_from_op":false,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."},{"msg_contents":"On Tue, 2021-10-26 at 23:32 +0900, Fujii Masao wrote:\n> The description \"This function is restricted to superusers by\n> default,\n> but other users can be granted EXECUTE to run the function.\"\n> should be added into the docs?\n\nA similar statement already exists right above the table of functions:\n\n\"\nUse of these functions is restricted to superusers by default but\naccess may be granted to others using GRANT, with noted exceptions.\"\n\n\nCommitted the version that merely removes the superuser check, and\nrevokes from public. Privilege can be granted to non-superusers if\ndesired.\n\nThanks everyone for looking.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 26 Oct 2021 14:04:14 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Allow pg_signal_backend members to use\n pg_log_backend_memory_stats()."}],"string":"[\n {\n \"msg_contents\": \"Simple patch to implement $SUBJECT attached.\\n\\npg_signal_backend seems like the appropriate predefined role, because\\npg_log_backend_memory_contexts() is implemented by a sending signal.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Sat, 23 Oct 2021 12:57:02 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On 10/23/21, 12:57 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> pg_signal_backend seems like the appropriate predefined role, because\\r\\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\\r\\n\\r\\nThis seems reasonable to me. The stated reason in the original commit\\r\\nmessage for keeping it restricted to superusers is because of the\\r\\ndenial-of-service risk, but if you've got pg_signal_backend, you can\\r\\nalready terminate sessions. The predefined roles documentation notes\\r\\nthat members of pg_signal_backend cannot signal superuser-owned\\r\\nbackends, but AFAICT pg_log_backend_memory_contexts() has no such\\r\\nrestriction at the moment. Should we add this?\\r\\n\\r\\nOtherwise, presumably we will need to update func.sgml and the comment\\r\\nabove pg_log_backend_memory_contexts() in mcxtfuncs.c.\\r\\n\\r\\nThis is unrelated to this patch, but should we also consider opening\\r\\nup pg_reload_conf() and pg_rotate_logfile() to members of\\r\\npg_signal_backend? Those are the other \\\"server signaling functions\\\" I\\r\\nsee in the docs.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Sat, 23 Oct 2021 20:42:29 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sat, Oct 23, 2021 at 08:42:29PM +0000, Bossart, Nathan wrote:\\n> Otherwise, presumably we will need to update func.sgml and the comment\\n> above pg_log_backend_memory_contexts() in mcxtfuncs.c.\\n\\nYes, the documentation of any SQL function whose hardcoded superuser()\\ncheck is removed needs a refresh to outline that its execution can be\\nGRANT-ed post-initialization, and it should also document which system\\nroles are able to use it. See for instance pg_database_size(), that\\nmentions roles need to be a member of pg_read_all_stats.\\n\\n> This is unrelated to this patch, but should we also consider opening\\n> up pg_reload_conf() and pg_rotate_logfile() to members of\\n> pg_signal_backend? Those are the other \\\"server signaling functions\\\" I\\n> see in the docs.\\n\\nYes, there is that as well.\\n\\n+CREATE ROLE testrole1 IN ROLE pg_signal_backend;\\n+CREATE ROLE testrole2;\\nAny role created in the regression test needs to be prefixed with\\n\\\"regress_\\\", or builds with -DENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS\\nwill complain (I just add that by default to not fall into this trap\\nagain).\\n--\\nMichael\",\n \"msg_date\": \"Sun, 24 Oct 2021 08:41:52 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 1:27 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n>\\n> Simple patch to implement $SUBJECT attached.\\n>\\n> pg_signal_backend seems like the appropriate predefined role, because\\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\\n\\n+1.\\n\\nIt looks like we are better off with removing explicit superuser()\\nchecks from the functions and using normal GRANT based system, see\\nothers agreeing on this at [1]. As we have lots of functions that are\\ndoing explicit superuser() checks, I'm sure someday they all will have\\nto be moved to GRANT system. The current code is a mix - some\\nfunctions do explicit checks (I've seen many of them with the comment\\nat [2]) and others do it via GRANT system. I'm not saying that we\\nshould be dealing with those here in this thread, all I'm looking for\\nis that we have a note of it in the postgres todo list in the wiki so\\nthat someone interested can pick that work up. Thoughts?\\n\\nComments on the patch:\\n1) testrole1 and testrole2 look generic, how about\\nregress_mcxt_role1/2? There's no problem as they are\\nmisc_functions.sql local, but still role names can be more readable.\\n+CREATE ROLE testrole1 IN ROLE pg_signal_backend;\\n+CREATE ROLE testrole2;\\n2) It seems like the privileges.sql is the right place to place the\\ntest cases, but I'm fine with keeping all the test cases of the\\nfunction together.\\n3) It might be enough to do has_function_privilege, just a thought -\\nisn't it better if we execute the function with the test roles set in.\\nThis will help us catch the permission denied error message in the\\ntest output files.\\n4) Isn't the +#define CATALOG_VERSION_NO 202110230 going to be set to\\nthe date on which the patch gets committed?\\n5) The following change is being handled in the patch at [3], I know\\nit is appropriate to have it in this patch, but please mention it in\\nthe commit message on why we do this change. I will remove this change\\nfrom my patch at [3].\\n-SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\\n+SELECT pg_log_backend_memory_contexts(pg_backend_pid());\\n\\n[1] - https://www.postgresql.org/message-id/CAOuzzgpp0dmOFjWC4JDvk57ZQGm8umCrFdR1at4b80xuF0XChw%40mail.gmail.com\\n[2] -\\n * Permission checking for this function is managed through the normal\\n * GRANT system.\\n */\\n[3] - https://www.postgresql.org/message-id/CALj2ACVXk1roswqFpiCOMHrsB%2BxxW7HG536krGAzF%3DmWXh3eWQ%40mail.gmail.com\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 19:58:16 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\\n> The predefined roles documentation notes\\n> that members of pg_signal_backend cannot signal superuser-owned\\n> backends, but AFAICT pg_log_backend_memory_contexts() has no such\\n> restriction at the moment. Should we add this?\\n\\nAdded, good catch.\\n\\n> This is unrelated to this patch, but should we also consider opening\\n> up pg_reload_conf() and pg_rotate_logfile() to members of\\n> pg_signal_backend? Those are the other \\\"server signaling functions\\\"\\n> I\\n> see in the docs.\\n\\nThose are actually signalling the postmaster, not an ordinary backend.\\nAlso, those functions are already GRANTable, so I think we should leave\\nthem as-is.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Sun, 24 Oct 2021 09:50:58 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sun, 2021-10-24 at 19:58 +0530, Bharath Rupireddy wrote:\\n> It looks like we are better off with removing explicit superuser()\\n> checks from the functions and using normal GRANT based system, see\\n> others agreeing on this at [1]. As we have lots of functions that are\\n> doing explicit superuser() checks, I'm sure someday they all will\\n> have\\n> to be moved to GRANT system.\\n\\nNote that some functions have additional checks that can't be expressed\\nwith GRANT -- see pg_cancel_backend(), for example. But I agree in\\ngeneral that GRANT is the way to go most of the time.\\n\\n> The current code is a mix - some\\n> functions do explicit checks (I've seen many of them with the comment\\n> at [2]) and others do it via GRANT system. I'm not saying that we\\n> should be dealing with those here in this thread, all I'm looking for\\n> is that we have a note of it in the postgres todo list in the wiki so\\n> that someone interested can pick that work up. Thoughts?\\n\\nIt seems like there's agreement on the direction, but I don't know that\\nthere's a good place to write it down. Probably better to just fix as\\nmany of the functions as we can, and then when people add new ones,\\nthey'll copy the GRANT pattern rather than the explicit superuser\\ncheck.\\n\\n> Comments on the patch:\\n> 1) testrole1 and testrole2 look generic, how about\\n\\nMichael had a similar comment. Renamed, thank you.\\n\\n> 2) It seems like the privileges.sql is the right place to place the\\n> test cases, but I'm fine with keeping all the test cases of the\\n> function together.\\n\\nIf we add all the function privilege checks there, I think it will\\noverwhelm the other interesting tests happening in that file.\\n\\n> 3) It might be enough to do has_function_privilege, just a thought -\\n> isn't it better if we execute the function with the test roles set\\n> in.\\n> This will help us catch the permission denied error message in the\\n> test output files.\\n\\nMissed this comment. I'll tweak this before commit.\\n\\n> 4) Isn't the +#define CATALOG_VERSION_NO 202110230 going to be set to\\n> the date on which the patch gets committed?\\n\\nI just put it in there so that I wouldn't forget, but I'll update it at\\ncommit time.\\n\\n> 5) The following change is being handled in the patch at [3], I know\\n> it is appropriate to have it in this patch, but please mention it in\\n> the commit message on why we do this change. I will remove this\\n> change\\n> from my patch at [3].\\n> -SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\\n> +SELECT pg_log_backend_memory_contexts(pg_backend_pid());\\n\\nWhat would you like me to mention?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 10:04:48 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On 10/24/21, 9:51 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\\r\\n>> The predefined roles documentation notes\\r\\n>> that members of pg_signal_backend cannot signal superuser-owned\\r\\n>> backends, but AFAICT pg_log_backend_memory_contexts() has no such\\r\\n>> restriction at the moment. Should we add this?\\r\\n>\\r\\n> Added, good catch.\\r\\n\\r\\nThe new patch looks good to me.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 20:59:48 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"At Sun, 24 Oct 2021 09:50:58 -0700, Jeff Davis <pgsql@j-davis.com> wrote in \\n> On Sat, 2021-10-23 at 20:42 +0000, Bossart, Nathan wrote:\\n> > The predefined roles documentation notes\\n> > that members of pg_signal_backend cannot signal superuser-owned\\n> > backends, but AFAICT pg_log_backend_memory_contexts() has no such\\n> > restriction at the moment. Should we add this?\\n> \\n> Added, good catch.\\n> \\n> > This is unrelated to this patch, but should we also consider opening\\n> > up pg_reload_conf() and pg_rotate_logfile() to members of\\n> > pg_signal_backend? Those are the other \\\"server signaling functions\\\"\\n> > I\\n> > see in the docs.\\n> \\n> Those are actually signalling the postmaster, not an ordinary backend.\\n> Also, those functions are already GRANTable, so I think we should leave\\n> them as-is.\\n\\nI'm afraid that it might be wrong that all backend-signalling features\\nare allowed by that priviledge. pg_signal_backends is described in\\nthe doc as:\\n\\nhttps://www.postgresql.org/docs/devel/predefined-roles.html\\n\\n> Signal another backend to cancel a query or terminate its session.\\n\\nHere, the term \\\"signal\\\" there seems to mean interrupting something on\\nthat session or the session itself. Addition to that I don't think\\n\\\"terminate a session or the query on a session\\\" and \\\"log something on\\nanother session\\\" and \\\"rotate log file\\\" don't fall into the same\\ncategory in a severity view.\\n\\nIn other words, I don't think pg_signal_backends is not meant to\\ncontrol \\\"log something on another session\\\" or \\\"rotate log file\\\". It's\\ndanger that if we allow somewone to rotate log files, that means to\\nallow same user to terminate another session.\\n\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 11:53:33 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-10-25 at 11:53 +0900, Kyotaro Horiguchi wrote:\\n> In other words, I don't think pg_signal_backends is not meant to\\n> control \\\"log something on another session\\\" or \\\"rotate log file\\\". \\n> It's\\n> danger that if we allow somewone to rotate log files, that means to\\n> allow same user to terminate another session.\\n\\nThe current patch doesn't allow members of pg_signal_backend to rotate\\nthe log file.\\n\\nDo you think pg_signal_backend is the wrong group to allow usage of\\npg_log_backend_memory_contexts()? Alternatively, it could simply not\\nGRANT anything, and leave that up to the administrator to choose who\\ncan use it.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 20:31:37 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"At Sun, 24 Oct 2021 20:31:37 -0700, Jeff Davis <pgsql@j-davis.com> wrote in \\n> On Mon, 2021-10-25 at 11:53 +0900, Kyotaro Horiguchi wrote:\\n> > In other words, I don't think pg_signal_backends is not meant to\\n> > control \\\"log something on another session\\\" or \\\"rotate log file\\\". \\n> > It's\\n> > danger that if we allow somewone to rotate log files, that means to\\n> > allow same user to terminate another session.\\n> \\n> The current patch doesn't allow members of pg_signal_backend to rotate\\n> the log file.\\n\\nAh, sorry, I might have confused with some other discussion.\\n\\n> Do you think pg_signal_backend is the wrong group to allow usage of\\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n\\nYes. I think it would be danger that who is allowed to dump memory\\ncontext into log files by granting pg_signal_backend also can\\nterminate other backends.\\n\\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n> GRANT anything, and leave that up to the administrator to choose who\\n> can use it.\\n\\n*I* prefer that. I'm not sure I'm the only one to think so, though..\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:13:43 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 9:43 AM Kyotaro Horiguchi\\n<horikyota.ntt@gmail.com> wrote:\\n> > Do you think pg_signal_backend is the wrong group to allow usage of\\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n>\\n> Yes. I think it would be danger that who is allowed to dump memory\\n> context into log files by granting pg_signal_backend also can\\n> terminate other backends.\\n>\\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n> > GRANT anything, and leave that up to the administrator to choose who\\n> > can use it.\\n>\\n> *I* prefer that. I'm not sure I'm the only one to think so, though..\\n\\nHow about we have a separate predefined role for the functions that\\ndeal with server logs? I'm not sure if Mark Dilger's patch on new\\npredefined roles has one, if not, how about something like\\npg_write_server_log/pg_manage_server_log/some other name?\\n\\nIf not with a new predefined role, how about expanding the scope of\\nexisting pg_write_server_files role?\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 09:57:52 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 08:31:37PM -0700, Jeff Davis wrote:\\n> The current patch doesn't allow members of pg_signal_backend to rotate\\n> the log file.\\n> \\n> Do you think pg_signal_backend is the wrong group to allow usage of\\n> pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n> GRANT anything, and leave that up to the administrator to choose who\\n> can use it.\\n\\nHmm. Why don't you split the patch into two parts that can be\\ndiscussed separately then? There would be one to remove all the\\nsuperuser() checks you can think of, and a potential second to grant \\nthose function's execution to some system role.\\n\\nFWIW, if the barrier between a role and a function is thin, perhaps\\nwe'd better just limit ourselves to the removal of the superuser()\\nchecks for now rather than trying to plug more groups into the\\nfunctions. When I have dealt with such issues in the past, I tend to\\njust do the superuser()/REVOKE part without more GRANTs or even more\\nsystem roles, as this is enough to give room to users to do what they\\nwant with their clusters. And this is a no-brainer.\\n--\\nMichael\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:10:15 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 10:34 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > 5) The following change is being handled in the patch at [3], I know\\n> > it is appropriate to have it in this patch, but please mention it in\\n> > the commit message on why we do this change. I will remove this\\n> > change\\n> > from my patch at [3].\\n> > -SELECT * FROM pg_log_backend_memory_contexts(pg_backend_pid());\\n> > +SELECT pg_log_backend_memory_contexts(pg_backend_pid());\\n>\\n> What would you like me to mention?\\n\\nSomething like below in the commit message would be good:\\n\\\"While on this, change the way the tests use pg_log_backend_memory_contexts()\\nUsually for functions, we don't use \\\"SELECT-FROM-<<function>>\\\",\\nwe just use \\\"SELECT-<<function>>\\\".\\\"\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:44:51 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Mon, Oct 25, 2021 at 12:40 PM Michael Paquier <michael@paquier.xyz> wrote:\\n>\\n> On Sun, Oct 24, 2021 at 08:31:37PM -0700, Jeff Davis wrote:\\n> > The current patch doesn't allow members of pg_signal_backend to rotate\\n> > the log file.\\n> >\\n> > Do you think pg_signal_backend is the wrong group to allow usage of\\n> > pg_log_backend_memory_contexts()? Alternatively, it could simply not\\n> > GRANT anything, and leave that up to the administrator to choose who\\n> > can use it.\\n>\\n> Hmm. Why don't you split the patch into two parts that can be\\n> discussed separately then? There would be one to remove all the\\n> superuser() checks you can think of, and a potential second to grant\\n> those function's execution to some system role.\\n\\nIMO, in this thread we can focus on remvong the\\npg_log_backend_memory_contexts()'s superuser() check and +1 to start a\\nseparate thread to remove superuser() checks for the other functions\\nand REVOKE the permissions in appropriate places, for system functins\\nsystem_functions.sql files, for extension functions, the extension\\ninstallation .sql files. See [1] and [2].\\n\\n[1] - https://www.postgresql.org/message-id/CALj2ACUhCFSUQmZhiQ%2Bw1kZdJGmhNP2cd1LZS4GVGowyjiqftQ%40mail.gmail.com\\n[2] - https://www.postgresql.org/message-id/CAOuzzgpp0dmOFjWC4JDvk57ZQGm8umCrFdR1at4b80xuF0XChw%40mail.gmail.com\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:49:57 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On 10/25/21, 2:21 AM, \\\"Bharath Rupireddy\\\" <bharath.rupireddyforpostgres@gmail.com> wrote:\\r\\n> On Mon, Oct 25, 2021 at 12:40 PM Michael Paquier <michael@paquier.xyz> wrote:\\r\\n>> Hmm. Why don't you split the patch into two parts that can be\\r\\n>> discussed separately then? There would be one to remove all the\\r\\n>> superuser() checks you can think of, and a potential second to grant\\r\\n>> those function's execution to some system role.\\r\\n>\\r\\n> IMO, in this thread we can focus on remvong the\\r\\n> pg_log_backend_memory_contexts()'s superuser() check and +1 to start a\\r\\n> separate thread to remove superuser() checks for the other functions\\r\\n> and REVOKE the permissions in appropriate places, for system functins\\r\\n> system_functions.sql files, for extension functions, the extension\\r\\n> installation .sql files. See [1] and [2].\\r\\n\\r\\nI like the general idea of removing hard-coded superuser checks first\\r\\nand granting execution to predefined roles second. I don't have any\\r\\nstrong opinion about what should be done in this thread and what\\r\\nshould be done elsewhere.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:15:20 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-23 12:57:02 -0700, Jeff Davis wrote:\\n> Simple patch to implement $SUBJECT attached.\\n> \\n> pg_signal_backend seems like the appropriate predefined role, because\\n> pg_log_backend_memory_contexts() is implemented by a sending signal.\\n\\nI like the idea of making pg_log_backend_memory_contexts() more widely\\navailable. But I think tying it to pg_signal_backend isn't great. It's\\nunnecessarily baking in an implementation detail.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 10:29:39 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\\n> Hmm. Why don't you split the patch into two parts that can be\\n> discussed separately then? There would be one to remove all the\\n> superuser() checks you can think of, and a potential second to grant \\n> those function's execution to some system role.\\n\\nGood idea. Attached a patch to remove the superuser check on\\npg_log_backend_memory_contexts(), except in the case when trying to log\\nmemory contexts of a superuser backend.\\n\\nUsing pg_signal_backend does not seem to be universally acceptable, so\\nI'll just drop the idea of granting to that predefined role.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:42:07 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On 10/25/21, 1:43 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\\r\\n>> Hmm. Why don't you split the patch into two parts that can be\\r\\n>> discussed separately then? There would be one to remove all the\\r\\n>> superuser() checks you can think of, and a potential second to grant\\r\\n>> those function's execution to some system role.\\r\\n>\\r\\n> Good idea. Attached a patch to remove the superuser check on\\r\\n> pg_log_backend_memory_contexts(), except in the case when trying to log\\r\\n> memory contexts of a superuser backend.\\r\\n\\r\\nLGTM.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 21:26:47 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-25 13:42:07 -0700, Jeff Davis wrote:\\n> Good idea. Attached a patch to remove the superuser check on\\n> pg_log_backend_memory_contexts(), except in the case when trying to log\\n> memory contexts of a superuser backend.\\n\\nI don't get the reasoning behind the \\\"except ...\\\" logic. What does this\\nactually protect against? A reasonable use case for this feature is is to\\nmonitor memory usage of all backends, and this restriction practially requires\\nto still use a security definer function.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:30:38 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-10-25 at 14:30 -0700, Andres Freund wrote:\\n> I don't get the reasoning behind the \\\"except ...\\\" logic. What does\\n> this\\n> actually protect against? A reasonable use case for this feature is\\n> is to\\n> monitor memory usage of all backends, and this restriction practially\\n> requires\\n> to still use a security definer function.\\n\\nNathan brought it up -- more as a question than a request, so perhaps\\nit's not necessary. I don't have a strong opinion about it, but I\\nincluded it to be conservative (easier to relax a privilege than to\\ntighten one).\\n\\nI can cut out the in-function check entirely if there's no objection.\\n\\nRegards,\\n\\tJeff Davis\\n\\n[1] https://postgr.es/m/33F34F0C-BB16-48DE-B125-95D340A54AE8@amazon.com\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:28:13 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On 10/25/21, 4:29 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Mon, 2021-10-25 at 14:30 -0700, Andres Freund wrote:\\r\\n>> I don't get the reasoning behind the \\\"except ...\\\" logic. What does\\r\\n>> this\\r\\n>> actually protect against? A reasonable use case for this feature is\\r\\n>> is to\\r\\n>> monitor memory usage of all backends, and this restriction practially\\r\\n>> requires\\r\\n>> to still use a security definer function.\\r\\n>\\r\\n> Nathan brought it up -- more as a question than a request, so perhaps\\r\\n> it's not necessary. I don't have a strong opinion about it, but I\\r\\n> included it to be conservative (easier to relax a privilege than to\\r\\n> tighten one).\\r\\n\\r\\nI asked about it since we were going to grant execution to\\r\\npg_signal_backend, which (per the docs) shouldn't be able to signal a\\r\\nsuperuser-owned backend. I don't mind removing this now that the\\r\\npg_signal_backend part is removed.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 23:58:31 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2021/10/26 5:42, Jeff Davis wrote:\\n> On Mon, 2021-10-25 at 16:10 +0900, Michael Paquier wrote:\\n>> Hmm. Why don't you split the patch into two parts that can be\\n>> discussed separately then? There would be one to remove all the\\n>> superuser() checks you can think of, and a potential second to grant\\n>> those function's execution to some system role.\\n> \\n> Good idea. Attached a patch to remove the superuser check on\\n> pg_log_backend_memory_contexts(), except in the case when trying to log\\n> memory contexts of a superuser backend.\\n\\n- Only superusers can request to log the memory contexts.\\n+ Only superusers can request to log the memory contexts of superuser\\n+ backends.\\n\\nThe description \\\"This function is restricted to superusers by default,\\nbut other users can be granted EXECUTE to run the function.\\\"\\nshould be added into the docs?\\n\\nRegards,\\n\\n-- \\nFujii Masao\\nAdvanced Computing Technology Center\\nResearch and Development Headquarters\\nNTT DATA CORPORATION\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 23:32:00 +0900\",\n \"msg_from\": \"Fujii Masao <masao.fujii@oss.nttdata.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-10-26 at 23:32 +0900, Fujii Masao wrote:\\n> The description \\\"This function is restricted to superusers by\\n> default,\\n> but other users can be granted EXECUTE to run the function.\\\"\\n> should be added into the docs?\\n\\nA similar statement already exists right above the table of functions:\\n\\n\\\"\\nUse of these functions is restricted to superusers by default but\\naccess may be granted to others using GRANT, with noted exceptions.\\\"\\n\\n\\nCommitted the version that merely removes the superuser check, and\\nrevokes from public. Privilege can be granted to non-superusers if\\ndesired.\\n\\nThanks everyone for looking.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 14:04:14 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Allow pg_signal_backend members to use\\n pg_log_backend_memory_stats().\"\n }\n]","isConversational":false}}},{"rowIdx":52988,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Add new predefined role pg_maintenance, which can issue VACUUM,\nANALYZE, CHECKPOINT.\n\nPatch attached.\n\nRegards,\n\tJeff Davis","msg_date":"Sat, 23 Oct 2021 14:45:02 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> Add new predefined role pg_maintenance, which can issue VACUUM,\n> ANALYZE, CHECKPOINT.\n>\n> Patch attached.\n\nAt this point, the idea of having a new role for maintenance work\nlooks good. With this patch and Mark Dilger's patch introducing a\nbunch of new predefined roles, one concern is that we might reach to a\nstate where we will have patches being proposed for new predefined\nroles for every database activity and the superuser eventually will\nhave nothing to do in the database, it just becomes dummy?\n\nI'm not sure if Mark Dilger's patch on new predefined roles has a\nsuitable/same role that we can use here.\n\nAre there any other database activities that fall under the\n\"maintenance\" category? How about CLUSTER, REINDEX? I didn't check the\ncode for their permissions.\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Sun, 24 Oct 2021 20:19:24 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sun, Oct 24, 2021 at 7:49 AM Bharath Rupireddy <\nbharath.rupireddyforpostgres@gmail.com> wrote:\n\n> On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\n> >\n> > Add new predefined role pg_maintenance, which can issue VACUUM,\n> > ANALYZE, CHECKPOINT.\n>\n>\n> Are there any other database activities that fall under the\n> \"maintenance\" category? How about CLUSTER, REINDEX? I didn't check the\n> code for their permissions.\n>\n>\nI would not lump the I/O intensive cluster and reindexing commands, and\nvacuum full, into the same permission bucket as vacuum and analyze.\nCheckpoint fits in the middle of that continuum. However, given that both\nvacuum and analyze are run to ensure good planner statistics during normal\nusage of the database, while the others, including checkpoint, either are\nnon-normal usage or don't influence the planner, I would shift checkpoint\nto the same permission that covers cluster and reindex.\n\nDavid J.\n\nOn Sun, Oct 24, 2021 at 7:49 AM Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\n>\n> Add new predefined role pg_maintenance, which can issue VACUUM,\n> ANALYZE, CHECKPOINT.\n\nAre there any other database activities that fall under the\n\"maintenance\" category? How about CLUSTER, REINDEX? I didn't check the\ncode for their permissions.I would not lump the I/O intensive cluster and reindexing commands, and vacuum full, into the same permission bucket as vacuum and analyze. Checkpoint fits in the middle of that continuum. However, given that both vacuum and analyze are run to ensure good planner statistics during normal usage of the database, while the others, including checkpoint, either are non-normal usage or don't influence the planner, I would shift checkpoint to the same permission that covers cluster and reindex.David J.","msg_date":"Sun, 24 Oct 2021 09:47:37 -0700","msg_from":"\"David G. Johnston\" <david.g.johnston@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sun, 2021-10-24 at 20:19 +0530, Bharath Rupireddy wrote:\n> At this point, the idea of having a new role for maintenance work\n> looks good. With this patch and Mark Dilger's patch introducing a\n> bunch of new predefined roles, one concern is that we might reach to\n> a\n> state where we will have patches being proposed for new predefined\n> roles for every database activity and the superuser eventually will\n> have nothing to do in the database, it just becomes dummy?\n\nThe idea is that, in different environments, the notion of an\n\"administrator\" should have different capabilities and different risks.\nBy making the privileges more fine-grained, we enable those different\nuse cases.\n\nI don't see it as necessarily a problem if superuser doesn't have much\nleft to do.\n\n> I'm not sure if Mark Dilger's patch on new predefined roles has a\n> suitable/same role that we can use here.\n\nI didn't see one. I think one of the most common reasons to do manual\ncheckpoints and vacuums is for performance testing, so another\npotential name might be \"pg_performance\". But \"pg_maintenance\" seemed a\nslightly better fit.\n\n> Are there any other database activities that fall under the\n> \"maintenance\" category? How about CLUSTER, REINDEX? I didn't check\n> the\n> code for their permissions.\n\nI looked around and didn't see much else to fit into this category.\nCLUSTER and REINDEX are a little too specific for a generic maintenance\noperation -- it's unlikely that you'd want to perform those expensive\noperations just to tidy up. But if you think something else should fit,\nlet me know.\n\nThank you,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sun, 24 Oct 2021 10:19:51 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/24/21, 10:20 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Sun, 2021-10-24 at 20:19 +0530, Bharath Rupireddy wrote:\r\n>> Are there any other database activities that fall under the\r\n>> \"maintenance\" category? How about CLUSTER, REINDEX? I didn't check\r\n>> the\r\n>> code for their permissions.\r\n>\r\n> I looked around and didn't see much else to fit into this category.\r\n> CLUSTER and REINDEX are a little too specific for a generic maintenance\r\n> operation -- it's unlikely that you'd want to perform those expensive\r\n> operations just to tidy up. But if you think something else should fit,\r\n> let me know.\r\n\r\nMy initial reaction was that members of pg_maintenance should be able\r\nto do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\r\nCHECKPOINT). It's true that some of these are more expensive or\r\ndisruptive than others, but how else could we divvy it up? Maybe one\r\noption is to have two separate roles, one for commands that require\r\nlower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\r\nFULL), and another for all of the maintenance commands.\r\n\r\nNathan\r\n\r\n","msg_date":"Sun, 24 Oct 2021 21:32:27 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\n> My initial reaction was that members of pg_maintenance should be able\n> to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\n> CHECKPOINT).\n\nWhat about REFRESH MATERIALIZED VIEW? That seems more specific to a\nworkload, but it's hard to draw a clear line between that and CLUSTER.\n\n> Maybe one\n> option is to have two separate roles, one for commands that require\n> lower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\n> FULL), and another for all of the maintenance commands.\n\nMy main motivation is CHECKPOINT and database-wide VACUUM and ANALYZE.\nI'm fine extending it if others think it would be worthwhile, but it\ngoes beyond my use case.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Sun, 24 Oct 2021 23:12:30 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/24/21, 11:13 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\r\n>> My initial reaction was that members of pg_maintenance should be able\r\n>> to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\r\n>> CHECKPOINT).\r\n>\r\n> What about REFRESH MATERIALIZED VIEW? That seems more specific to a\r\n> workload, but it's hard to draw a clear line between that and CLUSTER.\r\n\r\nHm. CLUSTER reorders the content of a table but does not change it.\r\nREFRESH MATERIALIZED VIEW, on the other hand, does replace the\r\ncontent. I think that's the sort of line I'd draw between REFRESH\r\nMATERIALIZED VIEW and the other commands as well, so I'd leave it out\r\nof pg_maintenance.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 25 Oct 2021 16:10:23 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Bharath Rupireddy (bharath.rupireddyforpostgres@gmail.com) wrote:\n> On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\n> > Add new predefined role pg_maintenance, which can issue VACUUM,\n> > ANALYZE, CHECKPOINT.\n> >\n> > Patch attached.\n> \n> At this point, the idea of having a new role for maintenance work\n> looks good. With this patch and Mark Dilger's patch introducing a\n> bunch of new predefined roles, one concern is that we might reach to a\n> state where we will have patches being proposed for new predefined\n> roles for every database activity and the superuser eventually will\n> have nothing to do in the database, it just becomes dummy?\n\nIndependent of other things, getting to the point where everything can\nbe done in the database without the need for superuser is absolutely a\ngood goal to be striving for, not something to be avoiding.\n\nI don't think that makes superuser become 'dummy', but perhaps the\nonly explicit superuser check we end up needing is \"superuser is a\nmember of all roles\". That would be a very cool end state.\n\nThanks,\n\nStephen","msg_date":"Mon, 25 Oct 2021 13:43:18 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Stephen Frost <sfrost@snowman.net> writes:\n> Independent of other things, getting to the point where everything can\n> be done in the database without the need for superuser is absolutely a\n> good goal to be striving for, not something to be avoiding.\n> I don't think that makes superuser become 'dummy', but perhaps the\n> only explicit superuser check we end up needing is \"superuser is a\n> member of all roles\". That would be a very cool end state.\n\nI'm not entirely following how that's going to work. It implies that\nthere is some allegedly-not-superuser role that has the ability to\nbecome superuser -- either within SQL or by breaking out to the OS --\nbecause certainly a superuser can do those things.\n\nI don't think we're serving any good purpose by giving people the\nimpression that roles with such permissions are somehow not\nsuperuser-equivalent. Certainly, the providers who don't want to\ngive users superuser are just going to need a longer list of roles\nthey won't give access to (and they probably won't be pleased about\nhaving to vet every predefined role carefully).\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Mon, 25 Oct 2021 13:51:56 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\n> > My initial reaction was that members of pg_maintenance should be able\n> > to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\n> > CHECKPOINT).\n> \n> What about REFRESH MATERIALIZED VIEW? That seems more specific to a\n> workload, but it's hard to draw a clear line between that and CLUSTER.\n\nLet's not forget that there are already existing non-superusers who can\nrun things like REFRESH MATERIALIZED VIEW- the owner.\n\n> > Maybe one\n> > option is to have two separate roles, one for commands that require\n> > lower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\n> > FULL), and another for all of the maintenance commands.\n> \n> My main motivation is CHECKPOINT and database-wide VACUUM and ANALYZE.\n> I'm fine extending it if others think it would be worthwhile, but it\n> goes beyond my use case.\n\nI've been wondering what the actual use-case here is. DB-wide VACUUM\nand ANALYZE are already able to be run by the database owner, but\nprobably more relevant is that DB-wide VACUUMs and ANALYZEs shouldn't\nreally be necessary given autovacuum, so why are we adding predefined\nroles which will encourage users to do that?\n\nI was also contemplating a different angle on this- allowing users to\nrequest autovacuum to run vacuum/analyze on a particular table. This\nwould have the advantage that you get the vacuum/analyze behavior that\nautovacuum has (giving up an attempted truncate lock if another process\nwants a lock on the table, going at a slower pace rather than going all\nout and sucking up lots of I/O, etc).\n\nI'm not completely against this approach but just would like a bit\nbetter understanding of why it makes sense and what things we'll be able\nto say about what this role can/cannot do.\n\nLastly though- I dislike the name, it seems far too general. I get that\nnaming things is hard but maybe we could find something better than\n'pg_maintenance' for this.\n\nThanks,\n\nStephen","msg_date":"Mon, 25 Oct 2021 13:54:43 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Tom Lane (tgl@sss.pgh.pa.us) wrote:\n> Stephen Frost <sfrost@snowman.net> writes:\n> > Independent of other things, getting to the point where everything can\n> > be done in the database without the need for superuser is absolutely a\n> > good goal to be striving for, not something to be avoiding.\n> > I don't think that makes superuser become 'dummy', but perhaps the\n> > only explicit superuser check we end up needing is \"superuser is a\n> > member of all roles\". That would be a very cool end state.\n> \n> I'm not entirely following how that's going to work. It implies that\n> there is some allegedly-not-superuser role that has the ability to\n> become superuser -- either within SQL or by breaking out to the OS --\n> because certainly a superuser can do those things.\n\nI don't think it implies that at all. Either that, or I'm not following\nwhat you're saying here. We have predefined roles today which aren't\nsuperusers and yet they're able to break out to the OS. Of course they\ncan become superusers if they put the effort in. None of that gets away\nfrom the more general idea that we could get to a point where all of a\nsuperuser's capabilities come from roles which the superuser is\nautomatically a member of such that we need have only one explicit\nsuperuser() check.\n\n> I don't think we're serving any good purpose by giving people the\n> impression that roles with such permissions are somehow not\n> superuser-equivalent. Certainly, the providers who don't want to\n> give users superuser are just going to need a longer list of roles\n> they won't give access to (and they probably won't be pleased about\n> having to vet every predefined role carefully).\n\nI agree that we need to be clear through the documentation about which\npredefined roles are able to \"break outside the box\" and become\nsuperuser, but that's independent from the question of if we will get to\na point where every capability the superuser has can also be given\nthrough membership in some predefined role or not.\n\nThat providers have to figure out what makes sense for them in terms of\nwhat they'll allow their users to do or not do doesn't seem entirely\nrelevant here- different providers are by definition different and some\nmight be fine with given out certain rights that others don't want to\ngive out. That's actually kind of the point of breaking out all of\nthese capabilities into more fine-grained ways of granting capabilities\nout.\n\nWe already have roles today which are ones that can break outside the\nbox and get to the OS and are able to do things that a superuser can do,\nor become a superuser themselves, and that's been generally a positive\nthing. We also have roles which are able to do things that only\nsuperusers used to be able to do but which are not able to become\nsuperusers themselves and aren't able to break out of the box. I don't\nsee any reason why we can't continue with this and eventually eliminate\nthe explicit superuser() checks except from the one where a superuser is\na member of all roles. Sure, some of those roles give capabilities\nwhich can be used to become superuser, while others don't, but I hardly\nsee that as an argument against the general idea that each is able to be\nindependently GRANT'd.\n\nIf nothing else, if we could eventually get to the point where there's\nonly one such explicit check then maybe we'd stop creating *new* places\nwhere capabilities are locked behind a superuser check. I did an audit\nonce upon a time of all superuser checks and rather than that number\ngoing down, as I had hoped at the time, it's been going up instead\nacross new releases. I view that as unfortunate.\n\nThanks,\n\nStephen","msg_date":"Mon, 25 Oct 2021 14:10:54 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Mon, 2021-10-25 at 13:54 -0400, Stephen Frost wrote:\n> Let's not forget that there are already existing non-superusers who\n> can\n> run things like REFRESH MATERIALIZED VIEW- the owner.\n\nRight, that's one reason why I don't see a particular use case there.\n\nBut CHECKPOINT right now has an explicit superuser check, and it would\nbe nice to be able to avoid that.\n\nIt's pretty normal to issue a CHECKPOINT right after a data load and\nbefore running a performance test, right? Shouldn't there be some way\nto do that without superuser?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 25 Oct 2021 13:50:28 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 2021-Oct-25, Jeff Davis wrote:\n\n> But CHECKPOINT right now has an explicit superuser check, and it would\n> be nice to be able to avoid that.\n> \n> It's pretty normal to issue a CHECKPOINT right after a data load and\n> before running a performance test, right? Shouldn't there be some way\n> to do that without superuser?\n\nMaybe you just need pg_checkpointer.\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\n\n","msg_date":"Mon, 25 Oct 2021 17:55:36 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"\n\n> On Oct 24, 2021, at 7:49 AM, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:\n> \n> At this point, the idea of having a new role for maintenance work\n> looks good. With this patch and Mark Dilger's patch introducing a\n> bunch of new predefined roles, one concern is that we might reach to a\n> state where we will have patches being proposed for new predefined\n> roles for every database activity and the superuser eventually will\n> have nothing to do in the database, it just becomes dummy?\n> \n> I'm not sure if Mark Dilger's patch on new predefined roles has a\n> suitable/same role that we can use here.\n\nIf you refer to the ALTER SYSTEM SET patches, which I agree introduce a number of new predefined roles, it may interest you that Andrew has requested that I rework that patch set. In particular, he would like me to implement a new system of grants whereby the authority to ALTER SYSTEM SET can be granted per GUC rather than having predefined roles which hardcoded privileges.\n\nI have not withdrawn the ALTER SYSTEM SET patches yet, as I don't know if Andrew's proposal can be made to work, but I wouldn't recommend tying this pg_maintenance idea to that set.\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Mon, 25 Oct 2021 14:12:16 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Mon, 2021-10-25 at 17:55 -0300, Alvaro Herrera wrote:\n> Maybe you just need pg_checkpointer.\n\nFair enough. Attached simpler patch that only covers checkpoint, and\ncalls the role pg_checkpointer.\n\nRegards,\n\tJeff Davis","msg_date":"Mon, 25 Oct 2021 16:39:35 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/25/21, 4:40 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Mon, 2021-10-25 at 17:55 -0300, Alvaro Herrera wrote:\r\n>> Maybe you just need pg_checkpointer.\r\n>\r\n> Fair enough. Attached simpler patch that only covers checkpoint, and\r\n> calls the role pg_checkpointer.\r\n\r\nIt feels a bit excessive to introduce a new predefined role just for\r\nthis. Perhaps this could be accomplished with a new function that\r\ncould be granted.\r\n\r\nNathan\r\n\r\n","msg_date":"Tue, 26 Oct 2021 00:07:11 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\n> It feels a bit excessive to introduce a new predefined role just for\n> this. Perhaps this could be accomplished with a new function that\n> could be granted.\n\nIt would be nice if the syntax could be used, since it's pretty\nwidespread. I guess it does feel excessive to have its own predefined\nrole, but at the same time it's hard to group a command like CHECKPOINT\ninto a category. Maybe if we named it something like pg_performance or\nsomething we could make a larger group?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Mon, 25 Oct 2021 18:47:03 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/25/21, 6:48 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\r\n>> It feels a bit excessive to introduce a new predefined role just for\r\n>> this. Perhaps this could be accomplished with a new function that\r\n>> could be granted.\r\n>\r\n> It would be nice if the syntax could be used, since it's pretty\r\n> widespread. I guess it does feel excessive to have its own predefined\r\n> role, but at the same time it's hard to group a command like CHECKPOINT\r\n> into a category. Maybe if we named it something like pg_performance or\r\n> something we could make a larger group?\r\n\r\nI do think a larger group is desirable, but as is evidenced by this\r\nthread, it may be some time until we can figure out exactly how that\r\nwould look. I feel like there's general support for being able to\r\nallow non-superusers to CHECKPOINT and do other\r\nmaintenance/performance tasks, though.\r\n\r\nI think my main concern with pg_checkpointer is that it could set a\r\nprecedent for new predefined roles, and we'd end up with dozens or\r\nmore. But as long as new predefined roles aren't terribly expensive,\r\nmaybe that's not all that bad. The advantage of having a\r\npg_checkpointer role is that it enables users to grant just CHECKPOINT\r\nand nothing else. If we wanted a larger \"pg_performance\" group in the\r\nfuture, we could introduce that role and make it a member of\r\npg_checkpointer and others (similar to how pg_monitor works).\r\n\r\nNathan\r\n\r\n","msg_date":"Tue, 26 Oct 2021 16:28:54 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\n> > It feels a bit excessive to introduce a new predefined role just for\n> > this. Perhaps this could be accomplished with a new function that\n> > could be granted.\n> \n> It would be nice if the syntax could be used, since it's pretty\n> widespread. I guess it does feel excessive to have its own predefined\n> role, but at the same time it's hard to group a command like CHECKPOINT\n> into a category. Maybe if we named it something like pg_performance or\n> something we could make a larger group?\n\nFor the use-case presented, I don't really buy off on this argument.\nWe're talking about benchmarking tools, surely they can be and likely\nalready are updated with some regularity for new major versions of PG.\nI wonder also if there aren't other things besides this that would need\nto be changed for them to work as a non-superuser anyway too, meaning\nthis would be just one change among others that they'd need to make.\n\nIn this specific case, I'd be more inclined to provide a function rather\nthan an explicit predefined role for this one thing.\n\nThanks,\n\nStephen","msg_date":"Tue, 26 Oct 2021 16:02:55 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2021-10-26 at 16:02 -0400, Stephen Frost wrote:\n> We're talking about benchmarking tools\n\nWhat I had in mind was something much less formal, like a self-\ncontained repro case of a performance problem.\n\n ... simple schema\n ... data load\n ... maybe build some indexes\n ... maybe set hints\n VACUUM ANALYZE;\n CHECKPOINT;\n\nI'm not saying it's a very strong use case, but at least for me, it's\nkind of a habit to throw in a CHECKPOINT after a quick data load for a\ntest, even if it might not matter for whatever I'm testing.\n\nI guess I can change my habit to use a function instead, but then\nwhat's the point of the syntax?\n\nShould we just add a builtin function pg_checkpoint(), and deprecate\nthe syntax?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 26 Oct 2021 14:03:24 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/26/21, 2:04 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> Should we just add a builtin function pg_checkpoint(), and deprecate\r\n> the syntax?\r\n\r\nThat seems reasonable to me.\r\n\r\nNathan\r\n\r\n","msg_date":"Tue, 26 Oct 2021 21:48:32 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Wed, Oct 27, 2021 at 3:18 AM Bossart, Nathan <bossartn@amazon.com> wrote:\n>\n> On 10/26/21, 2:04 PM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\n> > Should we just add a builtin function pg_checkpoint(), and deprecate\n> > the syntax?\n>\n> That seems reasonable to me.\n\nIMHO, moving away from SQL command \"CHECKPOINT\" to function\n\"pg_checkpoint()\" isn't nice as the SQL command has been there for a\nlong time and all the applications or services that were/are being\nbuilt around the postgres ecosystem would have to adapt someday to the\nnew function (if at all we deprecate the command and onboard the\nfunction). This isn't good at all given the CHECKPOINT is one of the\nmostly used commands in the apps or services layer. Moreover, if we go\nwith the function pg_checkpoint(), we might see patches coming in for\npg_vacuum(), pg_reindex(), pg_cluster() and so on.\n\nI suggest having a predefined role (pg_maintenance or\npg_checkpoint(although I'm not sure convinced to have a separate role\njust for checkpoint) or some other) and let superuser and the users\nwith this new predefined role do checkpoint.\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Sat, 30 Oct 2021 13:24:39 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\n> IMHO, moving away from SQL command \"CHECKPOINT\" to function\n> \"pg_checkpoint()\" isn't nice as the SQL command has been there for a\n> long time and all the applications or services that were/are being\n> built around the postgres ecosystem would have to adapt someday to\n> the\n> new function (if at all we deprecate the command and onboard the\n> function). This isn't good at all given the CHECKPOINT is one of the\n> mostly used commands in the apps or services layer. Moreover, if we\n> go\n> with the function pg_checkpoint(), we might see patches coming in for\n> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\n\nI tend to agree with all of this. The CHECKPOINT command is already\nthere and people already use it. If we are already chipping away at the\nneed for superuser elsewhere, we should offer a way to use CHECKPOINT\nwithout being superuser.\n\nIf the purpose[0] of predefined roles is that they allow you to do\nthings that can't be expressed by GRANT, a predefined role\npg_checkpointer seems to fit the bill.\n\nThe main argument against[1] having a pg_checkpointer predefined role\nis that it creates a clutter of predefined roles. But it seems like\njust another part of the clutter of having a special SQL command merely\nfor requesting a checkpoint.\n\nThe alternative of creating a new function doesn't seem to alleviate\nthe clutter. Some people will use the function and some will use the\ncommand, creating inconsistency in examples and scripts, and people\nwill wonder which one is the \"right\" one.\n\nRegards,\n\tJeff Davis\n\n[0] \nhttps://postgr.es/m/CA+TgmobQoWZn62qWRX+OOFjBPhdubxYTBeO-GSNPcLvBHh4ZvA@mail.gmail.com\n\n[1] https://postgr.es/m/8C661979-AF85-4AE1-9E2B-2A091DA3DB22@amazon.com\n\n\n\n","msg_date":"Sat, 30 Oct 2021 11:14:35 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 2021-Oct-30, Jeff Davis wrote:\n\n> I tend to agree with all of this. The CHECKPOINT command is already\n> there and people already use it. If we are already chipping away at the\n> need for superuser elsewhere, we should offer a way to use CHECKPOINT\n> without being superuser.\n\n+1\n\n> If the purpose[0] of predefined roles is that they allow you to do\n> things that can't be expressed by GRANT, a predefined role\n> pg_checkpointer seems to fit the bill.\n\n+1\n\n> The main argument against[1] having a pg_checkpointer predefined role\n> is that it creates a clutter of predefined roles. But it seems like\n> just another part of the clutter of having a special SQL command merely\n> for requesting a checkpoint.\n\n+1\n\n-- \nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\nY una voz del caos me habló y me dijo\n\"Sonríe y sé feliz, podría ser peor\".\nY sonreí. Y fui feliz.\nY fue peor.\n\n\n","msg_date":"Sat, 30 Oct 2021 21:26:26 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 10/30/21, 11:14 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\r\n>> IMHO, moving away from SQL command \"CHECKPOINT\" to function\r\n>> \"pg_checkpoint()\" isn't nice as the SQL command has been there for a\r\n>> long time and all the applications or services that were/are being\r\n>> built around the postgres ecosystem would have to adapt someday to\r\n>> the\r\n>> new function (if at all we deprecate the command and onboard the\r\n>> function). This isn't good at all given the CHECKPOINT is one of the\r\n>> mostly used commands in the apps or services layer. Moreover, if we\r\n>> go\r\n>> with the function pg_checkpoint(), we might see patches coming in for\r\n>> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\r\n>\r\n> I tend to agree with all of this. The CHECKPOINT command is already\r\n> there and people already use it. If we are already chipping away at the\r\n> need for superuser elsewhere, we should offer a way to use CHECKPOINT\r\n> without being superuser.\r\n\r\nI think Bharath brings up some good points. The simple fact is that\r\nCHECKPOINT has been around for a while, and creating functions for\r\nmaintenance tasks would add just as much or more clutter than adding a\r\npredefined role for each one. I do wonder what we would've done if\r\nCHECKPOINT didn't already exist. Based on the goal of this thread, I\r\nget the feeling that we might've seriously considered introducing it\r\nas a function so that you can just GRANT EXECUTE as needed. \r\n\r\nNathan\r\n\r\n","msg_date":"Sun, 31 Oct 2021 01:05:47 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Bossart, Nathan (bossartn@amazon.com) wrote:\n> On 10/30/21, 11:14 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\n> > On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\n> >> IMHO, moving away from SQL command \"CHECKPOINT\" to function\n> >> \"pg_checkpoint()\" isn't nice as the SQL command has been there for a\n> >> long time and all the applications or services that were/are being\n> >> built around the postgres ecosystem would have to adapt someday to\n> >> the\n> >> new function (if at all we deprecate the command and onboard the\n> >> function). This isn't good at all given the CHECKPOINT is one of the\n> >> mostly used commands in the apps or services layer. Moreover, if we\n> >> go\n> >> with the function pg_checkpoint(), we might see patches coming in for\n> >> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\n> >\n> > I tend to agree with all of this. The CHECKPOINT command is already\n> > there and people already use it. If we are already chipping away at the\n> > need for superuser elsewhere, we should offer a way to use CHECKPOINT\n> > without being superuser.\n> \n> I think Bharath brings up some good points. The simple fact is that\n> CHECKPOINT has been around for a while, and creating functions for\n> maintenance tasks would add just as much or more clutter than adding a\n> predefined role for each one. I do wonder what we would've done if\n> CHECKPOINT didn't already exist. Based on the goal of this thread, I\n> get the feeling that we might've seriously considered introducing it\n> as a function so that you can just GRANT EXECUTE as needed. \n\nI don't really buy off on the \"because it's been around a long time\" as\na reason to invent a predefined role for an individual command that\ndoesn't take any options and could certainly just be a function.\nApplications developed to run as a superuser aren't likely to magically\nstart working because they were GRANT'd this one additional predefined\nrole either but likely would need other changes anyway.\n\nAll that said, I wonder if we can have our cake and eat it too. I\nhaven't looked into this at all yet and perhaps it's foolish on its\nface, but, could we make CHECKPOINT; basically turn around and just run\nselect pg_checkpoint(); with the regular privilege checking happening?\nThen we'd keep the existing syntax working, but if the user is allowed\nto run the command would depend on if they've been GRANT'd EXECUTE\nrights on the function or not.\n\nThanks,\n\nStephen","msg_date":"Mon, 1 Nov 2021 12:50:25 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/1/21, 9:51 AM, \"Stephen Frost\" <sfrost@snowman.net> wrote:\r\n> I don't really buy off on the \"because it's been around a long time\" as\r\n> a reason to invent a predefined role for an individual command that\r\n> doesn't take any options and could certainly just be a function.\r\n> Applications developed to run as a superuser aren't likely to magically\r\n> start working because they were GRANT'd this one additional predefined\r\n> role either but likely would need other changes anyway.\r\n\r\nI suspect the CHECKPOINT command wouldn't be removed anytime soon,\r\neither. I definitely understand the desire to avoid changing\r\nsomething that's been around a long time, but I think a function fits\r\nbetter in this case.\r\n\r\n> All that said, I wonder if we can have our cake and eat it too. I\r\n> haven't looked into this at all yet and perhaps it's foolish on its\r\n> face, but, could we make CHECKPOINT; basically turn around and just run\r\n> select pg_checkpoint(); with the regular privilege checking happening?\r\n> Then we'd keep the existing syntax working, but if the user is allowed\r\n> to run the command would depend on if they've been GRANT'd EXECUTE\r\n> rights on the function or not.\r\n\r\nI'd be worried about the behavior of CHECKPOINT changing because\r\nsomeone messed with the function.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 1 Nov 2021 17:23:35 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Bossart, Nathan (bossartn@amazon.com) wrote:\n> On 11/1/21, 9:51 AM, \"Stephen Frost\" <sfrost@snowman.net> wrote:\n> > All that said, I wonder if we can have our cake and eat it too. I\n> > haven't looked into this at all yet and perhaps it's foolish on its\n> > face, but, could we make CHECKPOINT; basically turn around and just run\n> > select pg_checkpoint(); with the regular privilege checking happening?\n> > Then we'd keep the existing syntax working, but if the user is allowed\n> > to run the command would depend on if they've been GRANT'd EXECUTE\n> > rights on the function or not.\n> \n> I'd be worried about the behavior of CHECKPOINT changing because\n> someone messed with the function.\n\nFolks playing around in the catalog can break lots of things, I don't\nreally see this as an argument against the idea.\n\nI do wonder if we should put a bit more effort into preventing people\nfrom messing with functions and such in pg_catalog. Being able to do\nsomething like:\n\ncreate or replace function xpath ( text, xml ) returns xml[]\nas $$ begin return 'xml'; end; $$ language plpgsql;\n\n(or with much worse functions..) strikes me as just a bit too easy to\nmistakenly cause problems as a superuser. Still, that's really an\nindependent issue from this discussion. It's not like someone breaking\nCHECKPOINT; would actually impact normal checkpoints anyway.\n\nThanks,\n\nStephen","msg_date":"Mon, 1 Nov 2021 13:42:35 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/1/21, 10:43 AM, \"Stephen Frost\" <sfrost@snowman.net> wrote:\r\n> Folks playing around in the catalog can break lots of things, I don't\r\n> really see this as an argument against the idea.\r\n>\r\n> I do wonder if we should put a bit more effort into preventing people\r\n> from messing with functions and such in pg_catalog. Being able to do\r\n> something like:\r\n>\r\n> create or replace function xpath ( text, xml ) returns xml[]\r\n> as $$ begin return 'xml'; end; $$ language plpgsql;\r\n>\r\n> (or with much worse functions..) strikes me as just a bit too easy to\r\n> mistakenly cause problems as a superuser. Still, that's really an\r\n> independent issue from this discussion. It's not like someone breaking\r\n> CHECKPOINT; would actually impact normal checkpoints anyway.\r\n\r\nYeah, I see your point.\r\n\r\nNathan\r\n\r\n","msg_date":"Mon, 1 Nov 2021 18:38:14 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Sat, Oct 23, 2021 at 5:45 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> Add new predefined role pg_maintenance, which can issue VACUUM,\n> ANALYZE, CHECKPOINT.\n\nJust as a sort of general comment on this endeavor, I suspect that any\nattempt to lump things together that seem closely related is doomed to\nbackfire. There's bound to be somebody who wants to grant some of\nthese permissions and not others, or who wants to grant the ability to\nrun those commands on some tables but not others. That's kind of\nunfortunate because it makes it more complicated to implement stuff\nlike this ... but I've more or less given up hope on getting away with\nanything else.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Tue, 2 Nov 2021 11:06:39 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Mon, 2021-11-01 at 12:50 -0400, Stephen Frost wrote:\n> All that said, I wonder if we can have our cake and eat it too. I\n> haven't looked into this at all yet and perhaps it's foolish on its\n> face, but, could we make CHECKPOINT; basically turn around and just\n> run\n> select pg_checkpoint(); with the regular privilege checking\n> happening?\n> Then we'd keep the existing syntax working, but if the user is\n> allowed\n> to run the command would depend on if they've been GRANT'd EXECUTE\n> rights on the function or not.\n\nGreat idea! Patch attached.\n\nThis feels like a good pattern that we might want to use elsewhere, if\nthe need arises.\n\nRegards,\n\tJeff Davis","msg_date":"Tue, 02 Nov 2021 10:28:39 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2021-11-02 at 11:06 -0400, Robert Haas wrote:\n> Just as a sort of general comment on this endeavor, I suspect that\n> any\n> attempt to lump things together that seem closely related is doomed\n> to\n> backfire.\n\nAgreed, I think that is apparent from the different opinions in this\nthread.\n\nRobert had a good idea over here though:\n\nhttps://postgr.es/m/20211101165025.GS20998@tamriel.snowman.net\n\nwhich gives fine-grained control without the \"clutter\" of extra\npredefined roles.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Tue, 02 Nov 2021 10:35:43 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/2/21, 10:29 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\r\n> Great idea! Patch attached.\r\n>\r\n> This feels like a good pattern that we might want to use elsewhere, if\r\n> the need arises.\r\n\r\nThe approach in the patch looks alright to me, but another one could\r\nbe to build a SelectStmt when parsing CHECKPOINT. I think that'd\r\nsimplify the standard_ProcessUtility() changes.\r\n\r\nOtherwise, I see a couple of warnings when compiling:\r\n xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\r\n xlogfuncs.c:56: warning: control reaches end of non-void function\r\n\r\nNathan\r\n\r\n","msg_date":"Tue, 2 Nov 2021 17:45:49 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Tue, 2021-11-02 at 11:06 -0400, Robert Haas wrote:\n> > Just as a sort of general comment on this endeavor, I suspect that\n> > any\n> > attempt to lump things together that seem closely related is doomed\n> > to\n> > backfire.\n> \n> Agreed, I think that is apparent from the different opinions in this\n> thread.\n> \n> Robert had a good idea over here though:\n\nThink you meant 'Stephen' there. ;)\n\n> https://postgr.es/m/20211101165025.GS20998@tamriel.snowman.net\n> \n> which gives fine-grained control without the \"clutter\" of extra\n> predefined roles.\n\nRight.\n\n* Bossart, Nathan (bossartn@amazon.com) wrote:\n> On 11/2/21, 10:29 AM, \"Jeff Davis\" <pgsql@j-davis.com> wrote:\n> > Great idea! Patch attached.\n> >\n> > This feels like a good pattern that we might want to use elsewhere, if\n> > the need arises.\n> \n> The approach in the patch looks alright to me, but another one could\n> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\n> simplify the standard_ProcessUtility() changes.\n\nFor my 2c, at least, I'm not really partial to either approach, though\nI'd want to see what error messages end up looking like. Seems like we\nmight want to exercise a bit more control than we'd be able to if we\ntransformed it directly into a SelectStmt (that is, we might add a HINT:\nroles with execute rights on pg_checkpoint() can run this command, or\nsomething; maybe not too tho).\n\n> Otherwise, I see a couple of warnings when compiling:\n> xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\n> xlogfuncs.c:56: warning: control reaches end of non-void function\n\nYeah, such things would need to be cleaned up, of course.\n\nThanks!\n\nStephen","msg_date":"Tue, 2 Nov 2021 14:26:14 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/2/21, 11:27 AM, \"Stephen Frost\" <sfrost@snowman.net> wrote:\r\n> * Bossart, Nathan (bossartn@amazon.com) wrote:\r\n>> The approach in the patch looks alright to me, but another one could\r\n>> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\r\n>> simplify the standard_ProcessUtility() changes.\r\n>\r\n> For my 2c, at least, I'm not really partial to either approach, though\r\n> I'd want to see what error messages end up looking like. Seems like we\r\n> might want to exercise a bit more control than we'd be able to if we\r\n> transformed it directly into a SelectStmt (that is, we might add a HINT:\r\n> roles with execute rights on pg_checkpoint() can run this command, or\r\n> something; maybe not too tho).\r\n\r\nI don't feel strongly one way or the other as well, but you have a\r\ngood point about extra control over the error messages. The latest\r\npatch just does a standard aclcheck_error(), so you'd probably see\r\n\"permission denied for function\" if you didn't have privileges for\r\nCHECKPOINT. That could be confusing.\r\n\r\nNathan\r\n\r\n","msg_date":"Tue, 2 Nov 2021 21:06:58 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/2/21 4:06 PM, Robert Haas wrote:\n> There's bound to be somebody who wants to grant some of\n> these permissions and not others, or who wants to grant the ability to\n> run those commands on some tables but not others.\nIs there anything stopping us from adding syntax like this?\n\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\n\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\nbe done that way. I would much prefer that over new predefined roles.\n\nThis would be nice, but there is nothing to hang our hat on:\n\n GRANT CHECKPOINT TO username;\n-- \nVik Fearing\n\n\n","msg_date":"Tue, 2 Nov 2021 23:14:20 +0100","msg_from":"Vik Fearing <vik@postgresfriends.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, Nov 2, 2021 at 3:14 PM Vik Fearing <vik@postgresfriends.org> wrote:\n\n> On 11/2/21 4:06 PM, Robert Haas wrote:\n> > There's bound to be somebody who wants to grant some of\n> > these permissions and not others, or who wants to grant the ability to\n> > run those commands on some tables but not others.\n> Is there anything stopping us from adding syntax like this?\n>\n> GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\n>\n> That doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\n> be done that way. I would much prefer that over new predefined roles.\n>\n> This would be nice, but there is nothing to hang our hat on:\n>\n> GRANT CHECKPOINT TO username;\n>\n>\nHere is the thread when I last brought up this idea five years ago:\n\nhttps://www.postgresql.org/message-id/CAKFQuwaAhVt6audf92Q1VrELfJ%2BPz%3DuDfNb8%3D1_bqAmyDpnDmA%40mail.gmail.com\n\nI do not believe we've actually consumed any of the then available\npermission bits in the meanwhile.\n\nDavid J.\n\nOn Tue, Nov 2, 2021 at 3:14 PM Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 4:06 PM, Robert Haas wrote:\n> There's bound to be somebody who wants to grant some of\n> these permissions and not others, or who wants to grant the ability to\n> run those commands on some tables but not others.\nIs there anything stopping us from adding syntax like this?\n\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\n\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\nbe done that way. I would much prefer that over new predefined roles.\n\nThis would be nice, but there is nothing to hang our hat on:\n\n GRANT CHECKPOINT TO username;Here is the thread when I last brought up this idea five years ago:https://www.postgresql.org/message-id/CAKFQuwaAhVt6audf92Q1VrELfJ%2BPz%3DuDfNb8%3D1_bqAmyDpnDmA%40mail.gmail.comI do not believe we've actually consumed any of the then available permission bits in the meanwhile.David J.","msg_date":"Tue, 2 Nov 2021 15:30:25 -0700","msg_from":"\"David G. Johnston\" <david.g.johnston@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2 Nov 2021 at 18:14, Vik Fearing <vik@postgresfriends.org> wrote:\n\n> On 11/2/21 4:06 PM, Robert Haas wrote:\n> > There's bound to be somebody who wants to grant some of\n> > these permissions and not others, or who wants to grant the ability to\n> > run those commands on some tables but not others.\n> Is there anything stopping us from adding syntax like this?\n>\n> GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\n>\n\nThere is a limited number of bits available in the way privileges are\nstored. I investigated this in 2018 in connection with an idea I had to\nallow granting the ability to refresh a materialized view; after\nconsideration and discussion I came to the idea of having a \"MAINTAIN\"\npermission which would allow refreshing materialized views and would also\ncover clustering, reindexing, vacuuming, and analyzing on objects to which\nthose actions are applicable.\n\nThis message from me summarizes the history of usage of the available\nprivilege bits:\n\nhttps://www.postgresql.org/message-id/CAMsGm5c4DycKBYZCypfV02s-SC8GwF%2BKeTt%3D%3DvbWrFn%2Bdz%3DKeg%40mail.gmail.com\n\nIf you dig into the replies you will find the revised proposal.\n\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\n> be done that way. I would much prefer that over new predefined roles.\n>\n> This would be nice, but there is nothing to hang our hat on:\n>\n> GRANT CHECKPOINT TO username;\n>\n\nOn Tue, 2 Nov 2021 at 18:14, Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 4:06 PM, Robert Haas wrote:\n> There's bound to be somebody who wants to grant some of\n> these permissions and not others, or who wants to grant the ability to\n> run those commands on some tables but not others.\nIs there anything stopping us from adding syntax like this?\n\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;There is a limited number of bits available in the way privileges are stored. I investigated this in 2018 in connection with an idea I had to allow granting the ability to refresh a materialized view; after consideration and discussion I came to the idea of having a \"MAINTAIN\" permission which would allow refreshing materialized views and would also cover clustering, reindexing, vacuuming, and analyzing on objects to which those actions are applicable.This message from me summarizes the history of usage of the available privilege bits:https://www.postgresql.org/message-id/CAMsGm5c4DycKBYZCypfV02s-SC8GwF%2BKeTt%3D%3DvbWrFn%2Bdz%3DKeg%40mail.gmail.comIf you dig into the replies you will find the revised proposal.\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\nbe done that way. I would much prefer that over new predefined roles.\n\nThis would be nice, but there is nothing to hang our hat on:\n\n GRANT CHECKPOINT TO username;","msg_date":"Tue, 2 Nov 2021 18:43:52 -0400","msg_from":"Isaac Morland <isaac.morland@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 11/2/21 11:14 PM, Vik Fearing wrote:\n\n> This would be nice, but there is nothing to hang our hat on:\n> \n> GRANT CHECKPOINT TO username;\n\nThinking about this more, why don't we just add CHECKPOINT and\nNOCHECKPOINT attributes to roles?\n\n ALTER ROLE username WITH CHECKPOINT;\n-- \nVik Fearing\n\n\n","msg_date":"Wed, 3 Nov 2021 00:00:12 +0100","msg_from":"Vik Fearing <vik@postgresfriends.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:\n\n> On 11/2/21 11:14 PM, Vik Fearing wrote:\n>\n> > This would be nice, but there is nothing to hang our hat on:\n> >\n> > GRANT CHECKPOINT TO username;\n>\n> Thinking about this more, why don't we just add CHECKPOINT and\n> NOCHECKPOINT attributes to roles?\n>\n> ALTER ROLE username WITH CHECKPOINT;\n>\n\nAt present, this would require adding a field to pg_authid. This isn't very\nscalable; but we're already creating new pg_* roles which give access to\nvarious actions so I don't know why a role attribute would be a better\napproach. If anything, I think it would be more likely to move in the other\ndirection: replace role attributes that in effect grant privileges with\npredefined roles. I think this has already been discussed here in the\ncontext of CREATEROLE.\n\nOn Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 11:14 PM, Vik Fearing wrote:\n\n> This would be nice, but there is nothing to hang our hat on:\n> \n> GRANT CHECKPOINT TO username;\n\nThinking about this more, why don't we just add CHECKPOINT and\nNOCHECKPOINT attributes to roles?\n\n ALTER ROLE username WITH CHECKPOINT;\nAt present, this would require adding a field to pg_authid. This isn't very scalable; but we're already creating new pg_* roles which give access to various actions so I don't know why a role attribute would be a better approach. If anything, I think it would be more likely to move in the other direction: replace role attributes that in effect grant privileges with predefined roles. I think this has already been discussed here in the context of CREATEROLE.","msg_date":"Tue, 2 Nov 2021 20:08:27 -0400","msg_from":"Isaac Morland <isaac.morland@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"> On 2 Nov 2021, at 19:26, Stephen Frost <sfrost@snowman.net> wrote:\n\n>> Otherwise, I see a couple of warnings when compiling:\n>> xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\n>> xlogfuncs.c:56: warning: control reaches end of non-void function\n> \n> Yeah, such things would need to be cleaned up, of course.\n\nThe Commitfest CI has -Werror,-Wimplicit-function-declaration on some platforms\nin which this patch breaks, so I think we should apply the below (or something\nsimilar) to ensure this is tested everywhere:\n\ndiff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c\nindex 7ecaca4788..c9e1df39c1 100644\n--- a/src/backend/access/transam/xlogfuncs.c\n+++ b/src/backend/access/transam/xlogfuncs.c\n@@ -26,6 +26,7 @@\n #include \"funcapi.h\"\n #include \"miscadmin.h\"\n #include \"pgstat.h\"\n+#include \"postmaster/bgwriter.h\"\n #include \"replication/walreceiver.h\"\n #include \"storage/fd.h\"\n #include \"storage/ipc.h\"\n@@ -53,6 +54,7 @@ pg_checkpoint(PG_FUNCTION_ARGS)\n {\n RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT |\n (RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));\n+ PG_RETURN_VOID();\n }\n\n--\nDaniel Gustafsson\t\thttps://vmware.com/\n\n\n\n","msg_date":"Wed, 3 Nov 2021 15:02:20 +0100","msg_from":"Daniel Gustafsson <daniel@yesql.se>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Bossart, Nathan (bossartn@amazon.com) wrote:\n> On 11/2/21, 11:27 AM, \"Stephen Frost\" <sfrost@snowman.net> wrote:\n> > * Bossart, Nathan (bossartn@amazon.com) wrote:\n> >> The approach in the patch looks alright to me, but another one could\n> >> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\n> >> simplify the standard_ProcessUtility() changes.\n> >\n> > For my 2c, at least, I'm not really partial to either approach, though\n> > I'd want to see what error messages end up looking like. Seems like we\n> > might want to exercise a bit more control than we'd be able to if we\n> > transformed it directly into a SelectStmt (that is, we might add a HINT:\n> > roles with execute rights on pg_checkpoint() can run this command, or\n> > something; maybe not too tho).\n> \n> I don't feel strongly one way or the other as well, but you have a\n> good point about extra control over the error messages. The latest\n> patch just does a standard aclcheck_error(), so you'd probably see\n> \"permission denied for function\" if you didn't have privileges for\n> CHECKPOINT. That could be confusing.\n\nYeah, that's exactly the thing I was thinking about that might seem odd.\nI don't think it's a huge deal but I do think it'd be good for us to at\nleast think about if we're ok with that or if we want to try and do\nsomething a bit better.\n\nThanks,\n\nStephen","msg_date":"Wed, 3 Nov 2021 14:46:07 -0400","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Tue, 2021-11-02 at 14:26 -0400, Stephen Frost wrote:\n> Think you meant 'Stephen' there. ;)\n\nYes ;-)\n\n> > The approach in the patch looks alright to me, but another one\n> > could\n> > be to build a SelectStmt when parsing CHECKPOINT. I think that'd\n> > simplify the standard_ProcessUtility() changes.\n\nNathan, if I understand correctly, that would mean no CheckPointStmt at\nall. So it would either lack the right command tag, or we would have to\nhack it in somewhere. The utility changes in the existing patch are\nfairly minor, so I'll stick with that approach unless I'm missing\nsomething.\n\n> For my 2c, at least, I'm not really partial to either approach,\n> though\n> I'd want to see what error messages end up looking like. Seems like\n> we\n> might want to exercise a bit more control than we'd be able to if we\n> transformed it directly into a SelectStmt (that is, we might add a\n> HINT:\n> roles with execute rights on pg_checkpoint() can run this command, or\n> something; maybe not too tho).\n\nI changed the error message to:\n\n ERROR: permission denied for command CHECKPOINT\n HINT: The CHECKPOINT command requires the EXECUTE privilege\n on the function pg_checkpoint().\n\nNew version attached.\n\nAndres suggested that I also consider a new form of the GRANT clause\nthat works on the CHECKPOINT command directly. I looked into that\nbriefly, but in every other case it seems that GRANT works on an object\n(like a function). It doesn't feel like grating on a command is the\nright solution.\n\nThe approach of using a function's ACL to represent the ACL of a\nhigher-level command (as in this patch) does feel right to me. It feels\nlike something we might extend to similar situations in the future; and\neven if we don't, it seems like a clean solution in isolation.\n\nRegards,\n\tJeff Davis","msg_date":"Thu, 04 Nov 2021 09:03:52 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, Nov 4, 2021 at 12:03 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> The approach of using a function's ACL to represent the ACL of a\n> higher-level command (as in this patch) does feel right to me. It feels\n> like something we might extend to similar situations in the future; and\n> even if we don't, it seems like a clean solution in isolation.\n\nIt feels wrong to me. I realize that it's convenient to be able to\nre-use the existing GRANT and REVOKE commands that we have for\nfunctions, but actually DDL interfaces are better than SQL functions,\nbecause the syntax can be richer and you can avoid things like needing\nto take a snapshot. This particular patch dodges that problem, which\nis both a good thing and also clever, but it doesn't really make me\nfeel any better about the concept in general.\n\nI think that the ongoing pressure to reduce as many things as possible\nto function permissions checks is ultimately going to turn out to be\nan unpleasant dead end. But by the time we reach that dead end we'll\nhave put so much effort into making it work that it will be hard to\nchange course, for backward-compatibility reasons among others.\n\nI don't have anything specific to propose, which I realize is kind of\nunhelpful ... but I don't like this, either.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 4 Nov 2021 12:37:13 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\n> I don't have anything specific to propose, which I realize is kind of\n> unhelpful ... but I don't like this, either.\n\nWe can go back to having a pg_checkpoint predefined role that is only\nused for the CHECKPOINT command.\n\nThe only real argument against that was a general sense of clutter, but\nI wasn't entirely convinced of that. If we have a specialized command,\nwe have all kinds of clutter associated with that; a predefined role\ndoesn't add much additional clutter.\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Thu, 04 Nov 2021 14:25:54 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Hi,\n\nOn 2021-11-02 10:28:39 -0700, Jeff Davis wrote:\n> On Mon, 2021-11-01 at 12:50 -0400, Stephen Frost wrote:\n> > All that said, I wonder if we can have our cake and eat it too. I\n> > haven't looked into this at all yet and perhaps it's foolish on its\n> > face, but, could we make CHECKPOINT; basically turn around and just\n> > run\n> > select pg_checkpoint(); with the regular privilege checking\n> > happening?\n> > Then we'd keep the existing syntax working, but if the user is\n> > allowed\n> > to run the command would depend on if they've been GRANT'd EXECUTE\n> > rights on the function or not.\n> \n> Great idea! Patch attached.\n> \n> This feels like a good pattern that we might want to use elsewhere, if\n> the need arises.\n> \t\tcase T_CheckPointStmt:\n> -\t\t\tif (!superuser())\n> -\t\t\t\tereport(ERROR,\n> -\t\t\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n> -\t\t\t\t\t\t errmsg(\"must be superuser to do CHECKPOINT\")));\n> +\t\t\t{\n> +\t\t\t\t/*\n> +\t\t\t\t * Invoke pg_checkpoint(). Implementing the CHECKPOINT command\n> +\t\t\t\t * with a function allows administrators to grant privileges\n> +\t\t\t\t * on the CHECKPOINT command by granting privileges on the\n> +\t\t\t\t * pg_checkpoint() function. It also calls the function\n> +\t\t\t\t * execute hook, if present.\n> +\t\t\t\t */\n> +\t\t\t\tAclResult\taclresult;\n> +\t\t\t\tFmgrInfo\tflinfo;\n> +\n> +\t\t\t\taclresult = pg_proc_aclcheck(F_PG_CHECKPOINT, GetUserId(),\n> +\t\t\t\t\t\t\t\t\t\t\t ACL_EXECUTE);\n> +\t\t\t\tif (aclresult != ACLCHECK_OK)\n> +\t\t\t\t\taclcheck_error(aclresult, OBJECT_FUNCTION,\n> +\t\t\t\t\t\t\t\t get_func_name(F_PG_CHECKPOINT));\n> \n> -\t\t\tRequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT |\n> -\t\t\t\t\t\t\t (RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));\n> +\t\t\t\tInvokeFunctionExecuteHook(F_PG_CHECKPOINT);\n> +\n> +\t\t\t\tfmgr_info(F_PG_CHECKPOINT, &flinfo);\n> +\n> +\t\t\t\t(void) FunctionCall0Coll(&flinfo, InvalidOid);\n> +\t\t\t}\n> \t\t\tbreak;\n\nI don't like this. This turns the checkpoint command which previously didn't\nrely on the catalog in the happy path etc into something that requires most of\nthe backend to be happily up to work.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 4 Nov 2021 15:42:04 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Hi,\n\nOn 2021-11-04 14:25:54 -0700, Jeff Davis wrote:\n> On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\n> > I don't have anything specific to propose, which I realize is kind of\n> > unhelpful ... but I don't like this, either.\n> \n> We can go back to having a pg_checkpoint predefined role that is only\n> used for the CHECKPOINT command.\n\nWhat about extending GRANT to allow to grant rights on commands? Yes, it'd be\na bit of work to make that work in the catalogs, but it doesn't seem too hard\nto tackle.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 4 Nov 2021 15:46:36 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, 2021-11-04 at 15:46 -0700, Andres Freund wrote:\n> What about extending GRANT to allow to grant rights on commands? Yes,\n> it'd be\n> a bit of work to make that work in the catalogs, but it doesn't seem\n> too hard\n> to tackle.\n\nYou mean for the CHECKPOINT command specifically, or for many commands?\n\nIf it only applies to CHECKPOINT, it seems like more net clutter than a\nnew predefined role.\n\nBut I don't see it generalizing to a lot of commands, either. I looked\nat the list, and it's taking some creativity to think of more than a\ncouple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\neven then, there are three related commands: LISTEN, UNLISTEN, and\nNOTIFY. Are those one privilege representing them all, two\n(LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Thu, 04 Nov 2021 16:35:02 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, 2021-11-04 at 15:42 -0700, Andres Freund wrote:\n> I don't like this. This turns the checkpoint command which previously\n> didn't\n> rely on the catalog in the happy path etc into something that\n> requires most of\n> the backend to be happily up to work.\n\nIt seems like this specific approach has been mostly shot down already.\n But out of curiosity, are you intending to run CHECKPOINT during\nbootstrap or something?\n\nRegards,\n\tJeff Davis\n\n\n\n\n","msg_date":"Thu, 04 Nov 2021 16:38:36 -0700","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, Nov 4, 2021 at 5:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\n> > I don't have anything specific to propose, which I realize is kind of\n> > unhelpful ... but I don't like this, either.\n>\n> We can go back to having a pg_checkpoint predefined role that is only\n> used for the CHECKPOINT command.\n\nI would prefer that approach. Other people may prefer other things,\nbut if I got to pick, I'd say do it that way.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 5 Nov 2021 08:40:27 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> It seems like this specific approach has been mostly shot down already.\n> But out of curiosity, are you intending to run CHECKPOINT during\n> bootstrap or something?\n\nImagine a system with corruption in pg_proc. Right now, that won't\nprevent you from successfully executing a checkpoint. With this\napproach, it might.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 5 Nov 2021 08:42:58 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\n> What about extending GRANT to allow to grant rights on commands? Yes, it'd be\n> a bit of work to make that work in the catalogs, but it doesn't seem too hard\n> to tackle.\n\nI think that there aren't too many commands where the question is just\nwhether you can execute the command or not. CHECKPOINT is one that\ndoes work that way, but if it's VACUUM or ANALYZE the question will be\nwhether you can run it on a particular table; if it's ALTER SYSTEM it\nwill be whether you can run it for that GUC; and so on. CHECKPOINT is\none of the few commands that has no target.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 5 Nov 2021 08:54:37 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 2021-Nov-04, Jeff Davis wrote:\n\n> But I don't see it generalizing to a lot of commands, either. I looked\n> at the list, and it's taking some creativity to think of more than a\n> couple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\n> even then, there are three related commands: LISTEN, UNLISTEN, and\n> NOTIFY. Are those one privilege representing them all, two\n> (LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\n\nWhat about things like CREATE SUBSCRIPTION/PUBLICATION? Sounds like it\nwould be useful to allow non-superusers do those, too.\n\nThat said, if the list is short, then additional predefined roles seem\npreferrable to having a ton of infrastructure code that might be much\nmore clutter than what seems a short list of additional predefined roles.\n\n-- \nÁlvaro Herrera 39°49'30\"S 73°17'W — https://www.EnterpriseDB.com/\n\"We're here to devour each other alive\" (Hobbes)\n\n\n","msg_date":"Fri, 5 Nov 2021 10:13:11 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 2021-11-05 08:42:58 -0400, Robert Haas wrote:\n> On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > It seems like this specific approach has been mostly shot down already.\n> > But out of curiosity, are you intending to run CHECKPOINT during\n> > bootstrap or something?\n> \n> Imagine a system with corruption in pg_proc. Right now, that won't\n> prevent you from successfully executing a checkpoint. With this\n> approach, it might.\n\nExactly. It wouldn't matter if checkpoints weren't something needed to\npotentially bring the system back into a sane state, but ...\n\n\n","msg_date":"Sun, 7 Nov 2021 10:46:49 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Hi,\n\nOn 2021-11-05 08:54:37 -0400, Robert Haas wrote:\n> On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\n> > What about extending GRANT to allow to grant rights on commands? Yes, it'd be\n> > a bit of work to make that work in the catalogs, but it doesn't seem too hard\n> > to tackle.\n> \n> I think that there aren't too many commands where the question is just\n> whether you can execute the command or not. CHECKPOINT is one that\n> does work that way, but if it's VACUUM or ANALYZE the question will be\n> whether you can run it on a particular table; if it's ALTER SYSTEM it\n> will be whether you can run it for that GUC; and so on. CHECKPOINT is\n> one of the few commands that has no target.\n\nI don't know if that's really such a big deal. It's useful to be able to grant\nthe right to do a system wide ANALYZE etc to a role that can't otherwise do\nanything with the table. Even for ALTER SYSTEM etc it seems like it'd be\nhelpful, because it allows to constrain an admin tool to \"legitimate\" admin\npaths, without allowing, say, UPDATE pg_proc.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Sun, 7 Nov 2021 10:50:49 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Andres Freund (andres@anarazel.de) wrote:\n> On 2021-11-05 08:42:58 -0400, Robert Haas wrote:\n> > On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\n> > > It seems like this specific approach has been mostly shot down already.\n> > > But out of curiosity, are you intending to run CHECKPOINT during\n> > > bootstrap or something?\n> > \n> > Imagine a system with corruption in pg_proc. Right now, that won't\n> > prevent you from successfully executing a checkpoint. With this\n> > approach, it might.\n> \n> Exactly. It wouldn't matter if checkpoints weren't something needed to\n> potentially bring the system back into a sane state, but ...\n\nThis really isn't that hard to address- do a superuser check, if it\npasses then just call the checkpoint function like CHECKPOINT; does\ntoday. Otherwise, check the perms on the function or just call the\nfunction in a manner which would check privileges, or maybe have another\npredefined role, though I continue to feel like the function based\napproach is better.\n\nIf we're actually worried about catalog corruption (and, frankly, I've\ngot some serious doubts that jumping in and running CHECKPOINT; by hand\nis a great idea if there's such active corruption) then we must use such\nan approach no matter how we allow non-superusers to run the command\nbecause any approach to that necessarily involves some amount of catalog\naccess.\n\nAny concern leveraged against pg_proc applies equally to pg_auth_members\nafter all, so having it be something role-based vs. function privilege\nis really just moving deck chairs around on the titanic at that point.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 12:23:18 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Andres Freund (andres@anarazel.de) wrote:\n> On 2021-11-05 08:54:37 -0400, Robert Haas wrote:\n> > On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\n> > > What about extending GRANT to allow to grant rights on commands? Yes, it'd be\n> > > a bit of work to make that work in the catalogs, but it doesn't seem too hard\n> > > to tackle.\n> > \n> > I think that there aren't too many commands where the question is just\n> > whether you can execute the command or not. CHECKPOINT is one that\n> > does work that way, but if it's VACUUM or ANALYZE the question will be\n> > whether you can run it on a particular table; if it's ALTER SYSTEM it\n> > will be whether you can run it for that GUC; and so on. CHECKPOINT is\n> > one of the few commands that has no target.\n> \n> I don't know if that's really such a big deal. It's useful to be able to grant\n> the right to do a system wide ANALYZE etc to a role that can't otherwise do\n> anything with the table. Even for ALTER SYSTEM etc it seems like it'd be\n> helpful, because it allows to constrain an admin tool to \"legitimate\" admin\n> paths, without allowing, say, UPDATE pg_proc.\n\nNote that it's already possible to have a non-superuser who can run\nVACUUM and ANALYZE on all non-shared tables in a database but who\notherwise isn't able to mess with the tables owned by other users- that\nis something the database owner can do.\n\nPerhaps it's useful to break that out into a separately grantable\npermission but the argument should really by why you'd want to GRANT\nsomeone the ability to VACUUM/ANALYZE an entire database while *not*\nhaving them be the database owner. That's a much more narrow use-case\nvs. having them not be a superuser or be able to do things like UPDATE\npg_proc.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 12:32:38 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Hi,\n\nOn 2021-11-08 12:23:18 -0500, Stephen Frost wrote:\n> If we're actually worried about catalog corruption (and, frankly, I've\n> got some serious doubts that jumping in and running CHECKPOINT; by hand\n> is a great idea if there's such active corruption)\n\nI've been there when recovering from corruption.\n\n\n> though I continue to feel like the function based approach is better.\n\nI think it's a somewhat ugly hack.\n\n\n> then we must use such an approach no matter how we allow non-superusers to\n> run the command because any approach to that necessarily involves some\n> amount of catalog access.\n\nAs long as there's no additional catalog access when the user is known to be a\nsuperuser, then I think it's fine. There's a difference between doing one\npg_authid read for superuser - with a fallback to automatically assuming a\nuser if one couldn't be found - and doing a full pg_proc read with several\nsubsidiary pg_type reads etc.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Mon, 8 Nov 2021 09:33:25 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\n> On 2021-Nov-04, Jeff Davis wrote:\n> > But I don't see it generalizing to a lot of commands, either. I looked\n> > at the list, and it's taking some creativity to think of more than a\n> > couple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\n> > even then, there are three related commands: LISTEN, UNLISTEN, and\n> > NOTIFY. Are those one privilege representing them all, two\n> > (LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\n> \n> What about things like CREATE SUBSCRIPTION/PUBLICATION? Sounds like it\n> would be useful to allow non-superusers do those, too.\n\nAgreed. Having these be limited to superusers is unfortunate, though at\nthe time probably made sense as otherwise it would have made it that\nmuch more difficult to get logical replication in. Now is a great time\nto try and improve on that situation though. This is a bit tricky\nthough since creating a subscription means that you'll be able to cause\nsome code to be executed with higher privileges today, as I recall, and\nwe'd need to make sure to address that. If we can make sure that a\nsubscription isn't able to be used to execute code as effectively a\nsuperuser then I would think the other permission needed to create one,\nfor tables which you own, would be just a \"network access\" kind of\ncapability. In other words, I'm not 100% sure we need to have 'create\nsubscription' require different privileges from 'create a foreign\nserver'. Then again, having additional predefined rules isn't a huge\ncost and perhaps it would be better to avoid the confusion that\nintroducing a separate 'capabilities' kind of system would involve where\nthose capabilities cross multiple commands.\n\n> That said, if the list is short, then additional predefined roles seem\n> preferrable to having a ton of infrastructure code that might be much\n> more clutter than what seems a short list of additional predefined roles.\n\nNone of this strikes me as a 'ton of infrastructure code' and so I'm not\nquite sure I'm following the argument being made here.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 12:39:33 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On 2021-Nov-08, Stephen Frost wrote:\n\n> * Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\n\n> > That said, if the list is short, then additional predefined roles seem\n> > preferrable to having a ton of infrastructure code that might be much\n> > more clutter than what seems a short list of additional predefined roles.\n> \n> None of this strikes me as a 'ton of infrastructure code' and so I'm not\n> quite sure I'm following the argument being made here.\n\nI was referring specifically to Andres' idea of having additional DDL\ncommands handled as special GRANTable privileges, \nhttps://postgr.es/m/20211104224636.5qg6cfyjkw52rh4d@alap3.anarazel.de\n\n-- \nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\n\"Hay quien adquiere la mala costumbre de ser infeliz\" (M. A. Evans)\n\n\n","msg_date":"Mon, 8 Nov 2021 14:45:20 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Andres Freund (andres@anarazel.de) wrote:\n> On 2021-11-08 12:23:18 -0500, Stephen Frost wrote:\n> > though I continue to feel like the function based approach is better.\n> \n> I think it's a somewhat ugly hack.\n\nI suppose we'll just have to disagree on that. :)\n\nI don't feel as strongly as others apparently do on this point though,\nand I'd rather have non-superusers able to run CHECKPOINT *somehow*\nthan not, so if the others feel like a predefined role is a better\napproach then I'm alright with that. Seems a bit overkill to me but\nit's also not like it's actually all that much code or work to do.\n\n> > then we must use such an approach no matter how we allow non-superusers to\n> > run the command because any approach to that necessarily involves some\n> > amount of catalog access.\n> \n> As long as there's no additional catalog access when the user is known to be a\n> superuser, then I think it's fine. There's a difference between doing one\n> pg_authid read for superuser - with a fallback to automatically assuming a\n> user if one couldn't be found - and doing a full pg_proc read with several\n> subsidiary pg_type reads etc.\n\nYes, the approach I'm suggesting would make the superuser-run CHECKPOINT\nbe exactly the same as it is today, while a non-superuser trying to run\na CHECKPOINT would end up doing additional catalog accesses.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 12:47:23 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\n> On 2021-Nov-08, Stephen Frost wrote:\n> \n> > * Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\n> \n> > > That said, if the list is short, then additional predefined roles seem\n> > > preferrable to having a ton of infrastructure code that might be much\n> > > more clutter than what seems a short list of additional predefined roles.\n> > \n> > None of this strikes me as a 'ton of infrastructure code' and so I'm not\n> > quite sure I'm following the argument being made here.\n> \n> I was referring specifically to Andres' idea of having additional DDL\n> commands handled as special GRANTable privileges, \n> https://postgr.es/m/20211104224636.5qg6cfyjkw52rh4d@alap3.anarazel.de\n\nAh, thanks, I had seen that but didn't quite associate it to this\ncomment.\n\nPerhaps not a surprise, but I tend to favor predefined roles for these\nkinds of things. If we do want to revamp how GRANT works, I'd argue for\nfirst splitting up the way we handle privileges to be on a\nper-object-type basis and once we did that then we could extend that to\nallow GRANT on commands more easily (and with more variety as to what\nprivileges a GRANT on a command could be). It's kind of cute to have\none bitmap covering all objects but it puts us into a place where\nextending what can be GRANT'd on one kind of object necessarily impacts\nour ability to GRANT on other kinds (eg: we have a bit reserved for\nTRUNCATE in the same bitmask for a schema as we do for a table, but we\ndon't allow TRUNCATE on schemas and probably never will).\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 12:53:44 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Isaac Morland (isaac.morland@gmail.com) wrote:\n> On Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:\n> > On 11/2/21 11:14 PM, Vik Fearing wrote:\n> >\n> > > This would be nice, but there is nothing to hang our hat on:\n> > >\n> > > GRANT CHECKPOINT TO username;\n> >\n> > Thinking about this more, why don't we just add CHECKPOINT and\n> > NOCHECKPOINT attributes to roles?\n> >\n> > ALTER ROLE username WITH CHECKPOINT;\n> \n> At present, this would require adding a field to pg_authid. This isn't very\n> scalable; but we're already creating new pg_* roles which give access to\n> various actions so I don't know why a role attribute would be a better\n> approach. If anything, I think it would be more likely to move in the other\n> direction: replace role attributes that in effect grant privileges with\n> predefined roles. I think this has already been discussed here in the\n> context of CREATEROLE.\n\nYes, much better to create predefined roles for this kind of thing and,\nideally, move explicitly away from role attributes.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 14:11:57 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"On Mon, 2021-11-08 at 12:47 -0500, Stephen Frost wrote:\n> \n> I don't feel as strongly as others apparently do on this point\n> though,\n> and I'd rather have non-superusers able to run CHECKPOINT *somehow*\n> than not, so if the others feel like a predefined role is a better\n> approach then I'm alright with that. Seems a bit overkill to me but\n> it's also not like it's actually all that much code or work to do.\n\n+1. It seems like the pg_checkpointer predefined role is the most\nacceptable to everyone (even if not universally liked).\n\nAttached a rebased version of that patch.\n\nRegards,\n\tJeff Davis","msg_date":"Mon, 08 Nov 2021 16:13:17 -0800","msg_from":"Jeff Davis <pgsql@j-davis.com>","msg_from_op":true,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."},{"msg_contents":"Greetings,\n\n* Jeff Davis (pgsql@j-davis.com) wrote:\n> On Mon, 2021-11-08 at 12:47 -0500, Stephen Frost wrote:\n> > \n> > I don't feel as strongly as others apparently do on this point\n> > though,\n> > and I'd rather have non-superusers able to run CHECKPOINT *somehow*\n> > than not, so if the others feel like a predefined role is a better\n> > approach then I'm alright with that. Seems a bit overkill to me but\n> > it's also not like it's actually all that much code or work to do.\n> \n> +1. It seems like the pg_checkpointer predefined role is the most\n> acceptable to everyone (even if not universally liked).\n> \n> Attached a rebased version of that patch.\n\nThanks. Quick review-\n\n> diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c\n> index bf085aa93b2..0ff832a62c2 100644\n> --- a/src/backend/tcop/utility.c\n> +++ b/src/backend/tcop/utility.c\n> @@ -24,6 +24,7 @@\n> #include \"catalog/catalog.h\"\n> #include \"catalog/index.h\"\n> #include \"catalog/namespace.h\"\n> +#include \"catalog/pg_authid.h\"\n> #include \"catalog/pg_inherits.h\"\n> #include \"catalog/toasting.h\"\n> #include \"commands/alter.h\"\n> @@ -939,10 +940,10 @@ standard_ProcessUtility(PlannedStmt *pstmt,\n> \t\t\tbreak;\n> \n> \t\tcase T_CheckPointStmt:\n> -\t\t\tif (!superuser())\n> +\t\t\tif (!has_privs_of_role(GetUserId(), ROLE_PG_CHECKPOINTER))\n> \t\t\t\tereport(ERROR,\n> \t\t\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n> -\t\t\t\t\t\t errmsg(\"must be superuser to do CHECKPOINT\")));\n> +\t\t\t\t\t\t errmsg(\"must be member of pg_checkpointer to do CHECKPOINT\")));\n\nMost such error messages say 'superuser or '... Also, note the recent\nthread about trying to ensure that places are using has_privs_of_role()\nas you're doing here but also say that in the error message\nconsistently, rather than 'member of' it should really be 'has\nprivileges of' as the two are not necessarily always the same. You can\nbe a member of a role but not actively have the privileges of that role.\n\nOtherwise, looks pretty good to me. I'll note that has_privs_of_role()\nwill first call superuser_arg(member), just the same as the prior\nsuperuser() check did, so this doesn't change the catalog accesses in\nthat case from today.\n\nThanks,\n\nStephen","msg_date":"Tue, 9 Nov 2021 11:29:38 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT."}],"string":"[\n {\n \"msg_contents\": \"Add new predefined role pg_maintenance, which can issue VACUUM,\\nANALYZE, CHECKPOINT.\\n\\nPatch attached.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Sat, 23 Oct 2021 14:45:02 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> Add new predefined role pg_maintenance, which can issue VACUUM,\\n> ANALYZE, CHECKPOINT.\\n>\\n> Patch attached.\\n\\nAt this point, the idea of having a new role for maintenance work\\nlooks good. With this patch and Mark Dilger's patch introducing a\\nbunch of new predefined roles, one concern is that we might reach to a\\nstate where we will have patches being proposed for new predefined\\nroles for every database activity and the superuser eventually will\\nhave nothing to do in the database, it just becomes dummy?\\n\\nI'm not sure if Mark Dilger's patch on new predefined roles has a\\nsuitable/same role that we can use here.\\n\\nAre there any other database activities that fall under the\\n\\\"maintenance\\\" category? How about CLUSTER, REINDEX? I didn't check the\\ncode for their permissions.\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 20:19:24 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sun, Oct 24, 2021 at 7:49 AM Bharath Rupireddy <\\nbharath.rupireddyforpostgres@gmail.com> wrote:\\n\\n> On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> >\\n> > Add new predefined role pg_maintenance, which can issue VACUUM,\\n> > ANALYZE, CHECKPOINT.\\n>\\n>\\n> Are there any other database activities that fall under the\\n> \\\"maintenance\\\" category? How about CLUSTER, REINDEX? I didn't check the\\n> code for their permissions.\\n>\\n>\\nI would not lump the I/O intensive cluster and reindexing commands, and\\nvacuum full, into the same permission bucket as vacuum and analyze.\\nCheckpoint fits in the middle of that continuum. However, given that both\\nvacuum and analyze are run to ensure good planner statistics during normal\\nusage of the database, while the others, including checkpoint, either are\\nnon-normal usage or don't influence the planner, I would shift checkpoint\\nto the same permission that covers cluster and reindex.\\n\\nDavid J.\\n\\nOn Sun, Oct 24, 2021 at 7:49 AM Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n>\\n> Add new predefined role pg_maintenance, which can issue VACUUM,\\n> ANALYZE, CHECKPOINT.\\n\\nAre there any other database activities that fall under the\\n\\\"maintenance\\\" category? How about CLUSTER, REINDEX? I didn't check the\\ncode for their permissions.I would not lump the I/O intensive cluster and reindexing commands, and vacuum full, into the same permission bucket as vacuum and analyze. Checkpoint fits in the middle of that continuum. However, given that both vacuum and analyze are run to ensure good planner statistics during normal usage of the database, while the others, including checkpoint, either are non-normal usage or don't influence the planner, I would shift checkpoint to the same permission that covers cluster and reindex.David J.\",\n \"msg_date\": \"Sun, 24 Oct 2021 09:47:37 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sun, 2021-10-24 at 20:19 +0530, Bharath Rupireddy wrote:\\n> At this point, the idea of having a new role for maintenance work\\n> looks good. With this patch and Mark Dilger's patch introducing a\\n> bunch of new predefined roles, one concern is that we might reach to\\n> a\\n> state where we will have patches being proposed for new predefined\\n> roles for every database activity and the superuser eventually will\\n> have nothing to do in the database, it just becomes dummy?\\n\\nThe idea is that, in different environments, the notion of an\\n\\\"administrator\\\" should have different capabilities and different risks.\\nBy making the privileges more fine-grained, we enable those different\\nuse cases.\\n\\nI don't see it as necessarily a problem if superuser doesn't have much\\nleft to do.\\n\\n> I'm not sure if Mark Dilger's patch on new predefined roles has a\\n> suitable/same role that we can use here.\\n\\nI didn't see one. I think one of the most common reasons to do manual\\ncheckpoints and vacuums is for performance testing, so another\\npotential name might be \\\"pg_performance\\\". But \\\"pg_maintenance\\\" seemed a\\nslightly better fit.\\n\\n> Are there any other database activities that fall under the\\n> \\\"maintenance\\\" category? How about CLUSTER, REINDEX? I didn't check\\n> the\\n> code for their permissions.\\n\\nI looked around and didn't see much else to fit into this category.\\nCLUSTER and REINDEX are a little too specific for a generic maintenance\\noperation -- it's unlikely that you'd want to perform those expensive\\noperations just to tidy up. But if you think something else should fit,\\nlet me know.\\n\\nThank you,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 10:19:51 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/24/21, 10:20 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Sun, 2021-10-24 at 20:19 +0530, Bharath Rupireddy wrote:\\r\\n>> Are there any other database activities that fall under the\\r\\n>> \\\"maintenance\\\" category? How about CLUSTER, REINDEX? I didn't check\\r\\n>> the\\r\\n>> code for their permissions.\\r\\n>\\r\\n> I looked around and didn't see much else to fit into this category.\\r\\n> CLUSTER and REINDEX are a little too specific for a generic maintenance\\r\\n> operation -- it's unlikely that you'd want to perform those expensive\\r\\n> operations just to tidy up. But if you think something else should fit,\\r\\n> let me know.\\r\\n\\r\\nMy initial reaction was that members of pg_maintenance should be able\\r\\nto do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\\r\\nCHECKPOINT). It's true that some of these are more expensive or\\r\\ndisruptive than others, but how else could we divvy it up? Maybe one\\r\\noption is to have two separate roles, one for commands that require\\r\\nlower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\\r\\nFULL), and another for all of the maintenance commands.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 21:32:27 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\\n> My initial reaction was that members of pg_maintenance should be able\\n> to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\\n> CHECKPOINT).\\n\\nWhat about REFRESH MATERIALIZED VIEW? That seems more specific to a\\nworkload, but it's hard to draw a clear line between that and CLUSTER.\\n\\n> Maybe one\\n> option is to have two separate roles, one for commands that require\\n> lower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\\n> FULL), and another for all of the maintenance commands.\\n\\nMy main motivation is CHECKPOINT and database-wide VACUUM and ANALYZE.\\nI'm fine extending it if others think it would be worthwhile, but it\\ngoes beyond my use case.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Oct 2021 23:12:30 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/24/21, 11:13 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\\r\\n>> My initial reaction was that members of pg_maintenance should be able\\r\\n>> to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\\r\\n>> CHECKPOINT).\\r\\n>\\r\\n> What about REFRESH MATERIALIZED VIEW? That seems more specific to a\\r\\n> workload, but it's hard to draw a clear line between that and CLUSTER.\\r\\n\\r\\nHm. CLUSTER reorders the content of a table but does not change it.\\r\\nREFRESH MATERIALIZED VIEW, on the other hand, does replace the\\r\\ncontent. I think that's the sort of line I'd draw between REFRESH\\r\\nMATERIALIZED VIEW and the other commands as well, so I'd leave it out\\r\\nof pg_maintenance.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:10:23 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Bharath Rupireddy (bharath.rupireddyforpostgres@gmail.com) wrote:\\n> On Sun, Oct 24, 2021 at 3:15 AM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > Add new predefined role pg_maintenance, which can issue VACUUM,\\n> > ANALYZE, CHECKPOINT.\\n> >\\n> > Patch attached.\\n> \\n> At this point, the idea of having a new role for maintenance work\\n> looks good. With this patch and Mark Dilger's patch introducing a\\n> bunch of new predefined roles, one concern is that we might reach to a\\n> state where we will have patches being proposed for new predefined\\n> roles for every database activity and the superuser eventually will\\n> have nothing to do in the database, it just becomes dummy?\\n\\nIndependent of other things, getting to the point where everything can\\nbe done in the database without the need for superuser is absolutely a\\ngood goal to be striving for, not something to be avoiding.\\n\\nI don't think that makes superuser become 'dummy', but perhaps the\\nonly explicit superuser check we end up needing is \\\"superuser is a\\nmember of all roles\\\". That would be a very cool end state.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:43:18 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Stephen Frost <sfrost@snowman.net> writes:\\n> Independent of other things, getting to the point where everything can\\n> be done in the database without the need for superuser is absolutely a\\n> good goal to be striving for, not something to be avoiding.\\n> I don't think that makes superuser become 'dummy', but perhaps the\\n> only explicit superuser check we end up needing is \\\"superuser is a\\n> member of all roles\\\". That would be a very cool end state.\\n\\nI'm not entirely following how that's going to work. It implies that\\nthere is some allegedly-not-superuser role that has the ability to\\nbecome superuser -- either within SQL or by breaking out to the OS --\\nbecause certainly a superuser can do those things.\\n\\nI don't think we're serving any good purpose by giving people the\\nimpression that roles with such permissions are somehow not\\nsuperuser-equivalent. Certainly, the providers who don't want to\\ngive users superuser are just going to need a longer list of roles\\nthey won't give access to (and they probably won't be pleased about\\nhaving to vet every predefined role carefully).\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:51:56 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Sun, 2021-10-24 at 21:32 +0000, Bossart, Nathan wrote:\\n> > My initial reaction was that members of pg_maintenance should be able\\n> > to do all of these things (VACUUM, ANALYZE, CLUSTER, REINDEX, and\\n> > CHECKPOINT).\\n> \\n> What about REFRESH MATERIALIZED VIEW? That seems more specific to a\\n> workload, but it's hard to draw a clear line between that and CLUSTER.\\n\\nLet's not forget that there are already existing non-superusers who can\\nrun things like REFRESH MATERIALIZED VIEW- the owner.\\n\\n> > Maybe one\\n> > option is to have two separate roles, one for commands that require\\n> > lower lock levels (i.e., ANALYZE and VACUUM without TRUNCATE and\\n> > FULL), and another for all of the maintenance commands.\\n> \\n> My main motivation is CHECKPOINT and database-wide VACUUM and ANALYZE.\\n> I'm fine extending it if others think it would be worthwhile, but it\\n> goes beyond my use case.\\n\\nI've been wondering what the actual use-case here is. DB-wide VACUUM\\nand ANALYZE are already able to be run by the database owner, but\\nprobably more relevant is that DB-wide VACUUMs and ANALYZEs shouldn't\\nreally be necessary given autovacuum, so why are we adding predefined\\nroles which will encourage users to do that?\\n\\nI was also contemplating a different angle on this- allowing users to\\nrequest autovacuum to run vacuum/analyze on a particular table. This\\nwould have the advantage that you get the vacuum/analyze behavior that\\nautovacuum has (giving up an attempted truncate lock if another process\\nwants a lock on the table, going at a slower pace rather than going all\\nout and sucking up lots of I/O, etc).\\n\\nI'm not completely against this approach but just would like a bit\\nbetter understanding of why it makes sense and what things we'll be able\\nto say about what this role can/cannot do.\\n\\nLastly though- I dislike the name, it seems far too general. I get that\\nnaming things is hard but maybe we could find something better than\\n'pg_maintenance' for this.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:54:43 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Tom Lane (tgl@sss.pgh.pa.us) wrote:\\n> Stephen Frost <sfrost@snowman.net> writes:\\n> > Independent of other things, getting to the point where everything can\\n> > be done in the database without the need for superuser is absolutely a\\n> > good goal to be striving for, not something to be avoiding.\\n> > I don't think that makes superuser become 'dummy', but perhaps the\\n> > only explicit superuser check we end up needing is \\\"superuser is a\\n> > member of all roles\\\". That would be a very cool end state.\\n> \\n> I'm not entirely following how that's going to work. It implies that\\n> there is some allegedly-not-superuser role that has the ability to\\n> become superuser -- either within SQL or by breaking out to the OS --\\n> because certainly a superuser can do those things.\\n\\nI don't think it implies that at all. Either that, or I'm not following\\nwhat you're saying here. We have predefined roles today which aren't\\nsuperusers and yet they're able to break out to the OS. Of course they\\ncan become superusers if they put the effort in. None of that gets away\\nfrom the more general idea that we could get to a point where all of a\\nsuperuser's capabilities come from roles which the superuser is\\nautomatically a member of such that we need have only one explicit\\nsuperuser() check.\\n\\n> I don't think we're serving any good purpose by giving people the\\n> impression that roles with such permissions are somehow not\\n> superuser-equivalent. Certainly, the providers who don't want to\\n> give users superuser are just going to need a longer list of roles\\n> they won't give access to (and they probably won't be pleased about\\n> having to vet every predefined role carefully).\\n\\nI agree that we need to be clear through the documentation about which\\npredefined roles are able to \\\"break outside the box\\\" and become\\nsuperuser, but that's independent from the question of if we will get to\\na point where every capability the superuser has can also be given\\nthrough membership in some predefined role or not.\\n\\nThat providers have to figure out what makes sense for them in terms of\\nwhat they'll allow their users to do or not do doesn't seem entirely\\nrelevant here- different providers are by definition different and some\\nmight be fine with given out certain rights that others don't want to\\ngive out. That's actually kind of the point of breaking out all of\\nthese capabilities into more fine-grained ways of granting capabilities\\nout.\\n\\nWe already have roles today which are ones that can break outside the\\nbox and get to the OS and are able to do things that a superuser can do,\\nor become a superuser themselves, and that's been generally a positive\\nthing. We also have roles which are able to do things that only\\nsuperusers used to be able to do but which are not able to become\\nsuperusers themselves and aren't able to break out of the box. I don't\\nsee any reason why we can't continue with this and eventually eliminate\\nthe explicit superuser() checks except from the one where a superuser is\\na member of all roles. Sure, some of those roles give capabilities\\nwhich can be used to become superuser, while others don't, but I hardly\\nsee that as an argument against the general idea that each is able to be\\nindependently GRANT'd.\\n\\nIf nothing else, if we could eventually get to the point where there's\\nonly one such explicit check then maybe we'd stop creating *new* places\\nwhere capabilities are locked behind a superuser check. I did an audit\\nonce upon a time of all superuser checks and rather than that number\\ngoing down, as I had hoped at the time, it's been going up instead\\nacross new releases. I view that as unfortunate.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:10:54 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-10-25 at 13:54 -0400, Stephen Frost wrote:\\n> Let's not forget that there are already existing non-superusers who\\n> can\\n> run things like REFRESH MATERIALIZED VIEW- the owner.\\n\\nRight, that's one reason why I don't see a particular use case there.\\n\\nBut CHECKPOINT right now has an explicit superuser check, and it would\\nbe nice to be able to avoid that.\\n\\nIt's pretty normal to issue a CHECKPOINT right after a data load and\\nbefore running a performance test, right? Shouldn't there be some way\\nto do that without superuser?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 13:50:28 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-25, Jeff Davis wrote:\\n\\n> But CHECKPOINT right now has an explicit superuser check, and it would\\n> be nice to be able to avoid that.\\n> \\n> It's pretty normal to issue a CHECKPOINT right after a data load and\\n> before running a performance test, right? Shouldn't there be some way\\n> to do that without superuser?\\n\\nMaybe you just need pg_checkpointer.\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 17:55:36 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Oct 24, 2021, at 7:49 AM, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:\\n> \\n> At this point, the idea of having a new role for maintenance work\\n> looks good. With this patch and Mark Dilger's patch introducing a\\n> bunch of new predefined roles, one concern is that we might reach to a\\n> state where we will have patches being proposed for new predefined\\n> roles for every database activity and the superuser eventually will\\n> have nothing to do in the database, it just becomes dummy?\\n> \\n> I'm not sure if Mark Dilger's patch on new predefined roles has a\\n> suitable/same role that we can use here.\\n\\nIf you refer to the ALTER SYSTEM SET patches, which I agree introduce a number of new predefined roles, it may interest you that Andrew has requested that I rework that patch set. In particular, he would like me to implement a new system of grants whereby the authority to ALTER SYSTEM SET can be granted per GUC rather than having predefined roles which hardcoded privileges.\\n\\nI have not withdrawn the ALTER SYSTEM SET patches yet, as I don't know if Andrew's proposal can be made to work, but I wouldn't recommend tying this pg_maintenance idea to that set.\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 14:12:16 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-10-25 at 17:55 -0300, Alvaro Herrera wrote:\\n> Maybe you just need pg_checkpointer.\\n\\nFair enough. Attached simpler patch that only covers checkpoint, and\\ncalls the role pg_checkpointer.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Mon, 25 Oct 2021 16:39:35 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/25/21, 4:40 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Mon, 2021-10-25 at 17:55 -0300, Alvaro Herrera wrote:\\r\\n>> Maybe you just need pg_checkpointer.\\r\\n>\\r\\n> Fair enough. Attached simpler patch that only covers checkpoint, and\\r\\n> calls the role pg_checkpointer.\\r\\n\\r\\nIt feels a bit excessive to introduce a new predefined role just for\\r\\nthis. Perhaps this could be accomplished with a new function that\\r\\ncould be granted.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 00:07:11 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\\n> It feels a bit excessive to introduce a new predefined role just for\\n> this. Perhaps this could be accomplished with a new function that\\n> could be granted.\\n\\nIt would be nice if the syntax could be used, since it's pretty\\nwidespread. I guess it does feel excessive to have its own predefined\\nrole, but at the same time it's hard to group a command like CHECKPOINT\\ninto a category. Maybe if we named it something like pg_performance or\\nsomething we could make a larger group?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 18:47:03 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/25/21, 6:48 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\\r\\n>> It feels a bit excessive to introduce a new predefined role just for\\r\\n>> this. Perhaps this could be accomplished with a new function that\\r\\n>> could be granted.\\r\\n>\\r\\n> It would be nice if the syntax could be used, since it's pretty\\r\\n> widespread. I guess it does feel excessive to have its own predefined\\r\\n> role, but at the same time it's hard to group a command like CHECKPOINT\\r\\n> into a category. Maybe if we named it something like pg_performance or\\r\\n> something we could make a larger group?\\r\\n\\r\\nI do think a larger group is desirable, but as is evidenced by this\\r\\nthread, it may be some time until we can figure out exactly how that\\r\\nwould look. I feel like there's general support for being able to\\r\\nallow non-superusers to CHECKPOINT and do other\\r\\nmaintenance/performance tasks, though.\\r\\n\\r\\nI think my main concern with pg_checkpointer is that it could set a\\r\\nprecedent for new predefined roles, and we'd end up with dozens or\\r\\nmore. But as long as new predefined roles aren't terribly expensive,\\r\\nmaybe that's not all that bad. The advantage of having a\\r\\npg_checkpointer role is that it enables users to grant just CHECKPOINT\\r\\nand nothing else. If we wanted a larger \\\"pg_performance\\\" group in the\\r\\nfuture, we could introduce that role and make it a member of\\r\\npg_checkpointer and others (similar to how pg_monitor works).\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 16:28:54 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Tue, 2021-10-26 at 00:07 +0000, Bossart, Nathan wrote:\\n> > It feels a bit excessive to introduce a new predefined role just for\\n> > this. Perhaps this could be accomplished with a new function that\\n> > could be granted.\\n> \\n> It would be nice if the syntax could be used, since it's pretty\\n> widespread. I guess it does feel excessive to have its own predefined\\n> role, but at the same time it's hard to group a command like CHECKPOINT\\n> into a category. Maybe if we named it something like pg_performance or\\n> something we could make a larger group?\\n\\nFor the use-case presented, I don't really buy off on this argument.\\nWe're talking about benchmarking tools, surely they can be and likely\\nalready are updated with some regularity for new major versions of PG.\\nI wonder also if there aren't other things besides this that would need\\nto be changed for them to work as a non-superuser anyway too, meaning\\nthis would be just one change among others that they'd need to make.\\n\\nIn this specific case, I'd be more inclined to provide a function rather\\nthan an explicit predefined role for this one thing.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Tue, 26 Oct 2021 16:02:55 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-10-26 at 16:02 -0400, Stephen Frost wrote:\\n> We're talking about benchmarking tools\\n\\nWhat I had in mind was something much less formal, like a self-\\ncontained repro case of a performance problem.\\n\\n ... simple schema\\n ... data load\\n ... maybe build some indexes\\n ... maybe set hints\\n VACUUM ANALYZE;\\n CHECKPOINT;\\n\\nI'm not saying it's a very strong use case, but at least for me, it's\\nkind of a habit to throw in a CHECKPOINT after a quick data load for a\\ntest, even if it might not matter for whatever I'm testing.\\n\\nI guess I can change my habit to use a function instead, but then\\nwhat's the point of the syntax?\\n\\nShould we just add a builtin function pg_checkpoint(), and deprecate\\nthe syntax?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 14:03:24 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/26/21, 2:04 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> Should we just add a builtin function pg_checkpoint(), and deprecate\\r\\n> the syntax?\\r\\n\\r\\nThat seems reasonable to me.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 21:48:32 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 3:18 AM Bossart, Nathan <bossartn@amazon.com> wrote:\\n>\\n> On 10/26/21, 2:04 PM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\n> > Should we just add a builtin function pg_checkpoint(), and deprecate\\n> > the syntax?\\n>\\n> That seems reasonable to me.\\n\\nIMHO, moving away from SQL command \\\"CHECKPOINT\\\" to function\\n\\\"pg_checkpoint()\\\" isn't nice as the SQL command has been there for a\\nlong time and all the applications or services that were/are being\\nbuilt around the postgres ecosystem would have to adapt someday to the\\nnew function (if at all we deprecate the command and onboard the\\nfunction). This isn't good at all given the CHECKPOINT is one of the\\nmostly used commands in the apps or services layer. Moreover, if we go\\nwith the function pg_checkpoint(), we might see patches coming in for\\npg_vacuum(), pg_reindex(), pg_cluster() and so on.\\n\\nI suggest having a predefined role (pg_maintenance or\\npg_checkpoint(although I'm not sure convinced to have a separate role\\njust for checkpoint) or some other) and let superuser and the users\\nwith this new predefined role do checkpoint.\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Sat, 30 Oct 2021 13:24:39 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\\n> IMHO, moving away from SQL command \\\"CHECKPOINT\\\" to function\\n> \\\"pg_checkpoint()\\\" isn't nice as the SQL command has been there for a\\n> long time and all the applications or services that were/are being\\n> built around the postgres ecosystem would have to adapt someday to\\n> the\\n> new function (if at all we deprecate the command and onboard the\\n> function). This isn't good at all given the CHECKPOINT is one of the\\n> mostly used commands in the apps or services layer. Moreover, if we\\n> go\\n> with the function pg_checkpoint(), we might see patches coming in for\\n> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\\n\\nI tend to agree with all of this. The CHECKPOINT command is already\\nthere and people already use it. If we are already chipping away at the\\nneed for superuser elsewhere, we should offer a way to use CHECKPOINT\\nwithout being superuser.\\n\\nIf the purpose[0] of predefined roles is that they allow you to do\\nthings that can't be expressed by GRANT, a predefined role\\npg_checkpointer seems to fit the bill.\\n\\nThe main argument against[1] having a pg_checkpointer predefined role\\nis that it creates a clutter of predefined roles. But it seems like\\njust another part of the clutter of having a special SQL command merely\\nfor requesting a checkpoint.\\n\\nThe alternative of creating a new function doesn't seem to alleviate\\nthe clutter. Some people will use the function and some will use the\\ncommand, creating inconsistency in examples and scripts, and people\\nwill wonder which one is the \\\"right\\\" one.\\n\\nRegards,\\n\\tJeff Davis\\n\\n[0] \\nhttps://postgr.es/m/CA+TgmobQoWZn62qWRX+OOFjBPhdubxYTBeO-GSNPcLvBHh4ZvA@mail.gmail.com\\n\\n[1] https://postgr.es/m/8C661979-AF85-4AE1-9E2B-2A091DA3DB22@amazon.com\\n\\n\\n\\n\",\n \"msg_date\": \"Sat, 30 Oct 2021 11:14:35 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-30, Jeff Davis wrote:\\n\\n> I tend to agree with all of this. The CHECKPOINT command is already\\n> there and people already use it. If we are already chipping away at the\\n> need for superuser elsewhere, we should offer a way to use CHECKPOINT\\n> without being superuser.\\n\\n+1\\n\\n> If the purpose[0] of predefined roles is that they allow you to do\\n> things that can't be expressed by GRANT, a predefined role\\n> pg_checkpointer seems to fit the bill.\\n\\n+1\\n\\n> The main argument against[1] having a pg_checkpointer predefined role\\n> is that it creates a clutter of predefined roles. But it seems like\\n> just another part of the clutter of having a special SQL command merely\\n> for requesting a checkpoint.\\n\\n+1\\n\\n-- \\nÁlvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/\\nY una voz del caos me habló y me dijo\\n\\\"Sonríe y sé feliz, podría ser peor\\\".\\nY sonreí. Y fui feliz.\\nY fue peor.\\n\\n\\n\",\n \"msg_date\": \"Sat, 30 Oct 2021 21:26:26 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 10/30/21, 11:14 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\\r\\n>> IMHO, moving away from SQL command \\\"CHECKPOINT\\\" to function\\r\\n>> \\\"pg_checkpoint()\\\" isn't nice as the SQL command has been there for a\\r\\n>> long time and all the applications or services that were/are being\\r\\n>> built around the postgres ecosystem would have to adapt someday to\\r\\n>> the\\r\\n>> new function (if at all we deprecate the command and onboard the\\r\\n>> function). This isn't good at all given the CHECKPOINT is one of the\\r\\n>> mostly used commands in the apps or services layer. Moreover, if we\\r\\n>> go\\r\\n>> with the function pg_checkpoint(), we might see patches coming in for\\r\\n>> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\\r\\n>\\r\\n> I tend to agree with all of this. The CHECKPOINT command is already\\r\\n> there and people already use it. If we are already chipping away at the\\r\\n> need for superuser elsewhere, we should offer a way to use CHECKPOINT\\r\\n> without being superuser.\\r\\n\\r\\nI think Bharath brings up some good points. The simple fact is that\\r\\nCHECKPOINT has been around for a while, and creating functions for\\r\\nmaintenance tasks would add just as much or more clutter than adding a\\r\\npredefined role for each one. I do wonder what we would've done if\\r\\nCHECKPOINT didn't already exist. Based on the goal of this thread, I\\r\\nget the feeling that we might've seriously considered introducing it\\r\\nas a function so that you can just GRANT EXECUTE as needed. \\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Sun, 31 Oct 2021 01:05:47 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Bossart, Nathan (bossartn@amazon.com) wrote:\\n> On 10/30/21, 11:14 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\n> > On Sat, 2021-10-30 at 13:24 +0530, Bharath Rupireddy wrote:\\n> >> IMHO, moving away from SQL command \\\"CHECKPOINT\\\" to function\\n> >> \\\"pg_checkpoint()\\\" isn't nice as the SQL command has been there for a\\n> >> long time and all the applications or services that were/are being\\n> >> built around the postgres ecosystem would have to adapt someday to\\n> >> the\\n> >> new function (if at all we deprecate the command and onboard the\\n> >> function). This isn't good at all given the CHECKPOINT is one of the\\n> >> mostly used commands in the apps or services layer. Moreover, if we\\n> >> go\\n> >> with the function pg_checkpoint(), we might see patches coming in for\\n> >> pg_vacuum(), pg_reindex(), pg_cluster() and so on.\\n> >\\n> > I tend to agree with all of this. The CHECKPOINT command is already\\n> > there and people already use it. If we are already chipping away at the\\n> > need for superuser elsewhere, we should offer a way to use CHECKPOINT\\n> > without being superuser.\\n> \\n> I think Bharath brings up some good points. The simple fact is that\\n> CHECKPOINT has been around for a while, and creating functions for\\n> maintenance tasks would add just as much or more clutter than adding a\\n> predefined role for each one. I do wonder what we would've done if\\n> CHECKPOINT didn't already exist. Based on the goal of this thread, I\\n> get the feeling that we might've seriously considered introducing it\\n> as a function so that you can just GRANT EXECUTE as needed. \\n\\nI don't really buy off on the \\\"because it's been around a long time\\\" as\\na reason to invent a predefined role for an individual command that\\ndoesn't take any options and could certainly just be a function.\\nApplications developed to run as a superuser aren't likely to magically\\nstart working because they were GRANT'd this one additional predefined\\nrole either but likely would need other changes anyway.\\n\\nAll that said, I wonder if we can have our cake and eat it too. I\\nhaven't looked into this at all yet and perhaps it's foolish on its\\nface, but, could we make CHECKPOINT; basically turn around and just run\\nselect pg_checkpoint(); with the regular privilege checking happening?\\nThen we'd keep the existing syntax working, but if the user is allowed\\nto run the command would depend on if they've been GRANT'd EXECUTE\\nrights on the function or not.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 1 Nov 2021 12:50:25 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/1/21, 9:51 AM, \\\"Stephen Frost\\\" <sfrost@snowman.net> wrote:\\r\\n> I don't really buy off on the \\\"because it's been around a long time\\\" as\\r\\n> a reason to invent a predefined role for an individual command that\\r\\n> doesn't take any options and could certainly just be a function.\\r\\n> Applications developed to run as a superuser aren't likely to magically\\r\\n> start working because they were GRANT'd this one additional predefined\\r\\n> role either but likely would need other changes anyway.\\r\\n\\r\\nI suspect the CHECKPOINT command wouldn't be removed anytime soon,\\r\\neither. I definitely understand the desire to avoid changing\\r\\nsomething that's been around a long time, but I think a function fits\\r\\nbetter in this case.\\r\\n\\r\\n> All that said, I wonder if we can have our cake and eat it too. I\\r\\n> haven't looked into this at all yet and perhaps it's foolish on its\\r\\n> face, but, could we make CHECKPOINT; basically turn around and just run\\r\\n> select pg_checkpoint(); with the regular privilege checking happening?\\r\\n> Then we'd keep the existing syntax working, but if the user is allowed\\r\\n> to run the command would depend on if they've been GRANT'd EXECUTE\\r\\n> rights on the function or not.\\r\\n\\r\\nI'd be worried about the behavior of CHECKPOINT changing because\\r\\nsomeone messed with the function.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 17:23:35 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Bossart, Nathan (bossartn@amazon.com) wrote:\\n> On 11/1/21, 9:51 AM, \\\"Stephen Frost\\\" <sfrost@snowman.net> wrote:\\n> > All that said, I wonder if we can have our cake and eat it too. I\\n> > haven't looked into this at all yet and perhaps it's foolish on its\\n> > face, but, could we make CHECKPOINT; basically turn around and just run\\n> > select pg_checkpoint(); with the regular privilege checking happening?\\n> > Then we'd keep the existing syntax working, but if the user is allowed\\n> > to run the command would depend on if they've been GRANT'd EXECUTE\\n> > rights on the function or not.\\n> \\n> I'd be worried about the behavior of CHECKPOINT changing because\\n> someone messed with the function.\\n\\nFolks playing around in the catalog can break lots of things, I don't\\nreally see this as an argument against the idea.\\n\\nI do wonder if we should put a bit more effort into preventing people\\nfrom messing with functions and such in pg_catalog. Being able to do\\nsomething like:\\n\\ncreate or replace function xpath ( text, xml ) returns xml[]\\nas $$ begin return 'xml'; end; $$ language plpgsql;\\n\\n(or with much worse functions..) strikes me as just a bit too easy to\\nmistakenly cause problems as a superuser. Still, that's really an\\nindependent issue from this discussion. It's not like someone breaking\\nCHECKPOINT; would actually impact normal checkpoints anyway.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 1 Nov 2021 13:42:35 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/1/21, 10:43 AM, \\\"Stephen Frost\\\" <sfrost@snowman.net> wrote:\\r\\n> Folks playing around in the catalog can break lots of things, I don't\\r\\n> really see this as an argument against the idea.\\r\\n>\\r\\n> I do wonder if we should put a bit more effort into preventing people\\r\\n> from messing with functions and such in pg_catalog. Being able to do\\r\\n> something like:\\r\\n>\\r\\n> create or replace function xpath ( text, xml ) returns xml[]\\r\\n> as $$ begin return 'xml'; end; $$ language plpgsql;\\r\\n>\\r\\n> (or with much worse functions..) strikes me as just a bit too easy to\\r\\n> mistakenly cause problems as a superuser. Still, that's really an\\r\\n> independent issue from this discussion. It's not like someone breaking\\r\\n> CHECKPOINT; would actually impact normal checkpoints anyway.\\r\\n\\r\\nYeah, I see your point.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 18:38:14 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Sat, Oct 23, 2021 at 5:45 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> Add new predefined role pg_maintenance, which can issue VACUUM,\\n> ANALYZE, CHECKPOINT.\\n\\nJust as a sort of general comment on this endeavor, I suspect that any\\nattempt to lump things together that seem closely related is doomed to\\nbackfire. There's bound to be somebody who wants to grant some of\\nthese permissions and not others, or who wants to grant the ability to\\nrun those commands on some tables but not others. That's kind of\\nunfortunate because it makes it more complicated to implement stuff\\nlike this ... but I've more or less given up hope on getting away with\\nanything else.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 11:06:39 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-01 at 12:50 -0400, Stephen Frost wrote:\\n> All that said, I wonder if we can have our cake and eat it too. I\\n> haven't looked into this at all yet and perhaps it's foolish on its\\n> face, but, could we make CHECKPOINT; basically turn around and just\\n> run\\n> select pg_checkpoint(); with the regular privilege checking\\n> happening?\\n> Then we'd keep the existing syntax working, but if the user is\\n> allowed\\n> to run the command would depend on if they've been GRANT'd EXECUTE\\n> rights on the function or not.\\n\\nGreat idea! Patch attached.\\n\\nThis feels like a good pattern that we might want to use elsewhere, if\\nthe need arises.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Tue, 02 Nov 2021 10:28:39 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-11-02 at 11:06 -0400, Robert Haas wrote:\\n> Just as a sort of general comment on this endeavor, I suspect that\\n> any\\n> attempt to lump things together that seem closely related is doomed\\n> to\\n> backfire.\\n\\nAgreed, I think that is apparent from the different opinions in this\\nthread.\\n\\nRobert had a good idea over here though:\\n\\nhttps://postgr.es/m/20211101165025.GS20998@tamriel.snowman.net\\n\\nwhich gives fine-grained control without the \\\"clutter\\\" of extra\\npredefined roles.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 02 Nov 2021 10:35:43 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/2/21, 10:29 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\r\\n> Great idea! Patch attached.\\r\\n>\\r\\n> This feels like a good pattern that we might want to use elsewhere, if\\r\\n> the need arises.\\r\\n\\r\\nThe approach in the patch looks alright to me, but another one could\\r\\nbe to build a SelectStmt when parsing CHECKPOINT. I think that'd\\r\\nsimplify the standard_ProcessUtility() changes.\\r\\n\\r\\nOtherwise, I see a couple of warnings when compiling:\\r\\n xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\\r\\n xlogfuncs.c:56: warning: control reaches end of non-void function\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 17:45:49 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Tue, 2021-11-02 at 11:06 -0400, Robert Haas wrote:\\n> > Just as a sort of general comment on this endeavor, I suspect that\\n> > any\\n> > attempt to lump things together that seem closely related is doomed\\n> > to\\n> > backfire.\\n> \\n> Agreed, I think that is apparent from the different opinions in this\\n> thread.\\n> \\n> Robert had a good idea over here though:\\n\\nThink you meant 'Stephen' there. ;)\\n\\n> https://postgr.es/m/20211101165025.GS20998@tamriel.snowman.net\\n> \\n> which gives fine-grained control without the \\\"clutter\\\" of extra\\n> predefined roles.\\n\\nRight.\\n\\n* Bossart, Nathan (bossartn@amazon.com) wrote:\\n> On 11/2/21, 10:29 AM, \\\"Jeff Davis\\\" <pgsql@j-davis.com> wrote:\\n> > Great idea! Patch attached.\\n> >\\n> > This feels like a good pattern that we might want to use elsewhere, if\\n> > the need arises.\\n> \\n> The approach in the patch looks alright to me, but another one could\\n> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\\n> simplify the standard_ProcessUtility() changes.\\n\\nFor my 2c, at least, I'm not really partial to either approach, though\\nI'd want to see what error messages end up looking like. Seems like we\\nmight want to exercise a bit more control than we'd be able to if we\\ntransformed it directly into a SelectStmt (that is, we might add a HINT:\\nroles with execute rights on pg_checkpoint() can run this command, or\\nsomething; maybe not too tho).\\n\\n> Otherwise, I see a couple of warnings when compiling:\\n> xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\\n> xlogfuncs.c:56: warning: control reaches end of non-void function\\n\\nYeah, such things would need to be cleaned up, of course.\\n\\nThanks!\\n\\nStephen\",\n \"msg_date\": \"Tue, 2 Nov 2021 14:26:14 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/2/21, 11:27 AM, \\\"Stephen Frost\\\" <sfrost@snowman.net> wrote:\\r\\n> * Bossart, Nathan (bossartn@amazon.com) wrote:\\r\\n>> The approach in the patch looks alright to me, but another one could\\r\\n>> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\\r\\n>> simplify the standard_ProcessUtility() changes.\\r\\n>\\r\\n> For my 2c, at least, I'm not really partial to either approach, though\\r\\n> I'd want to see what error messages end up looking like. Seems like we\\r\\n> might want to exercise a bit more control than we'd be able to if we\\r\\n> transformed it directly into a SelectStmt (that is, we might add a HINT:\\r\\n> roles with execute rights on pg_checkpoint() can run this command, or\\r\\n> something; maybe not too tho).\\r\\n\\r\\nI don't feel strongly one way or the other as well, but you have a\\r\\ngood point about extra control over the error messages. The latest\\r\\npatch just does a standard aclcheck_error(), so you'd probably see\\r\\n\\\"permission denied for function\\\" if you didn't have privileges for\\r\\nCHECKPOINT. That could be confusing.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 21:06:58 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/2/21 4:06 PM, Robert Haas wrote:\\n> There's bound to be somebody who wants to grant some of\\n> these permissions and not others, or who wants to grant the ability to\\n> run those commands on some tables but not others.\\nIs there anything stopping us from adding syntax like this?\\n\\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\\n\\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\\nbe done that way. I would much prefer that over new predefined roles.\\n\\nThis would be nice, but there is nothing to hang our hat on:\\n\\n GRANT CHECKPOINT TO username;\\n-- \\nVik Fearing\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 23:14:20 +0100\",\n \"msg_from\": \"Vik Fearing <vik@postgresfriends.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, Nov 2, 2021 at 3:14 PM Vik Fearing <vik@postgresfriends.org> wrote:\\n\\n> On 11/2/21 4:06 PM, Robert Haas wrote:\\n> > There's bound to be somebody who wants to grant some of\\n> > these permissions and not others, or who wants to grant the ability to\\n> > run those commands on some tables but not others.\\n> Is there anything stopping us from adding syntax like this?\\n>\\n> GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\\n>\\n> That doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\\n> be done that way. I would much prefer that over new predefined roles.\\n>\\n> This would be nice, but there is nothing to hang our hat on:\\n>\\n> GRANT CHECKPOINT TO username;\\n>\\n>\\nHere is the thread when I last brought up this idea five years ago:\\n\\nhttps://www.postgresql.org/message-id/CAKFQuwaAhVt6audf92Q1VrELfJ%2BPz%3DuDfNb8%3D1_bqAmyDpnDmA%40mail.gmail.com\\n\\nI do not believe we've actually consumed any of the then available\\npermission bits in the meanwhile.\\n\\nDavid J.\\n\\nOn Tue, Nov 2, 2021 at 3:14 PM Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 4:06 PM, Robert Haas wrote:\\n> There's bound to be somebody who wants to grant some of\\n> these permissions and not others, or who wants to grant the ability to\\n> run those commands on some tables but not others.\\nIs there anything stopping us from adding syntax like this?\\n\\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\\n\\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\\nbe done that way. I would much prefer that over new predefined roles.\\n\\nThis would be nice, but there is nothing to hang our hat on:\\n\\n GRANT CHECKPOINT TO username;Here is the thread when I last brought up this idea five years ago:https://www.postgresql.org/message-id/CAKFQuwaAhVt6audf92Q1VrELfJ%2BPz%3DuDfNb8%3D1_bqAmyDpnDmA%40mail.gmail.comI do not believe we've actually consumed any of the then available permission bits in the meanwhile.David J.\",\n \"msg_date\": \"Tue, 2 Nov 2021 15:30:25 -0700\",\n \"msg_from\": \"\\\"David G. Johnston\\\" <david.g.johnston@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2 Nov 2021 at 18:14, Vik Fearing <vik@postgresfriends.org> wrote:\\n\\n> On 11/2/21 4:06 PM, Robert Haas wrote:\\n> > There's bound to be somebody who wants to grant some of\\n> > these permissions and not others, or who wants to grant the ability to\\n> > run those commands on some tables but not others.\\n> Is there anything stopping us from adding syntax like this?\\n>\\n> GRANT VACUUM, ANALYZE ON TABLE foo TO bar;\\n>\\n\\nThere is a limited number of bits available in the way privileges are\\nstored. I investigated this in 2018 in connection with an idea I had to\\nallow granting the ability to refresh a materialized view; after\\nconsideration and discussion I came to the idea of having a \\\"MAINTAIN\\\"\\npermission which would allow refreshing materialized views and would also\\ncover clustering, reindexing, vacuuming, and analyzing on objects to which\\nthose actions are applicable.\\n\\nThis message from me summarizes the history of usage of the available\\nprivilege bits:\\n\\nhttps://www.postgresql.org/message-id/CAMsGm5c4DycKBYZCypfV02s-SC8GwF%2BKeTt%3D%3DvbWrFn%2Bdz%3DKeg%40mail.gmail.com\\n\\nIf you dig into the replies you will find the revised proposal.\\n\\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\\n> be done that way. I would much prefer that over new predefined roles.\\n>\\n> This would be nice, but there is nothing to hang our hat on:\\n>\\n> GRANT CHECKPOINT TO username;\\n>\\n\\nOn Tue, 2 Nov 2021 at 18:14, Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 4:06 PM, Robert Haas wrote:\\n> There's bound to be somebody who wants to grant some of\\n> these permissions and not others, or who wants to grant the ability to\\n> run those commands on some tables but not others.\\nIs there anything stopping us from adding syntax like this?\\n\\n GRANT VACUUM, ANALYZE ON TABLE foo TO bar;There is a limited number of bits available in the way privileges are stored. I investigated this in 2018 in connection with an idea I had to allow granting the ability to refresh a materialized view; after consideration and discussion I came to the idea of having a \\\"MAINTAIN\\\" permission which would allow refreshing materialized views and would also cover clustering, reindexing, vacuuming, and analyzing on objects to which those actions are applicable.This message from me summarizes the history of usage of the available privilege bits:https://www.postgresql.org/message-id/CAMsGm5c4DycKBYZCypfV02s-SC8GwF%2BKeTt%3D%3DvbWrFn%2Bdz%3DKeg%40mail.gmail.comIf you dig into the replies you will find the revised proposal.\\nThat doesn't fix the CHECKPOINT issue, but surely vacuum and analyze can\\nbe done that way. I would much prefer that over new predefined roles.\\n\\nThis would be nice, but there is nothing to hang our hat on:\\n\\n GRANT CHECKPOINT TO username;\",\n \"msg_date\": \"Tue, 2 Nov 2021 18:43:52 -0400\",\n \"msg_from\": \"Isaac Morland <isaac.morland@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 11/2/21 11:14 PM, Vik Fearing wrote:\\n\\n> This would be nice, but there is nothing to hang our hat on:\\n> \\n> GRANT CHECKPOINT TO username;\\n\\nThinking about this more, why don't we just add CHECKPOINT and\\nNOCHECKPOINT attributes to roles?\\n\\n ALTER ROLE username WITH CHECKPOINT;\\n-- \\nVik Fearing\\n\\n\\n\",\n \"msg_date\": \"Wed, 3 Nov 2021 00:00:12 +0100\",\n \"msg_from\": \"Vik Fearing <vik@postgresfriends.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:\\n\\n> On 11/2/21 11:14 PM, Vik Fearing wrote:\\n>\\n> > This would be nice, but there is nothing to hang our hat on:\\n> >\\n> > GRANT CHECKPOINT TO username;\\n>\\n> Thinking about this more, why don't we just add CHECKPOINT and\\n> NOCHECKPOINT attributes to roles?\\n>\\n> ALTER ROLE username WITH CHECKPOINT;\\n>\\n\\nAt present, this would require adding a field to pg_authid. This isn't very\\nscalable; but we're already creating new pg_* roles which give access to\\nvarious actions so I don't know why a role attribute would be a better\\napproach. If anything, I think it would be more likely to move in the other\\ndirection: replace role attributes that in effect grant privileges with\\npredefined roles. I think this has already been discussed here in the\\ncontext of CREATEROLE.\\n\\nOn Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:On 11/2/21 11:14 PM, Vik Fearing wrote:\\n\\n> This would be nice, but there is nothing to hang our hat on:\\n> \\n> GRANT CHECKPOINT TO username;\\n\\nThinking about this more, why don't we just add CHECKPOINT and\\nNOCHECKPOINT attributes to roles?\\n\\n ALTER ROLE username WITH CHECKPOINT;\\nAt present, this would require adding a field to pg_authid. This isn't very scalable; but we're already creating new pg_* roles which give access to various actions so I don't know why a role attribute would be a better approach. If anything, I think it would be more likely to move in the other direction: replace role attributes that in effect grant privileges with predefined roles. I think this has already been discussed here in the context of CREATEROLE.\",\n \"msg_date\": \"Tue, 2 Nov 2021 20:08:27 -0400\",\n \"msg_from\": \"Isaac Morland <isaac.morland@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"> On 2 Nov 2021, at 19:26, Stephen Frost <sfrost@snowman.net> wrote:\\n\\n>> Otherwise, I see a couple of warnings when compiling:\\n>> xlogfuncs.c:54: warning: implicit declaration of function ‘RequestCheckpoint’\\n>> xlogfuncs.c:56: warning: control reaches end of non-void function\\n> \\n> Yeah, such things would need to be cleaned up, of course.\\n\\nThe Commitfest CI has -Werror,-Wimplicit-function-declaration on some platforms\\nin which this patch breaks, so I think we should apply the below (or something\\nsimilar) to ensure this is tested everywhere:\\n\\ndiff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c\\nindex 7ecaca4788..c9e1df39c1 100644\\n--- a/src/backend/access/transam/xlogfuncs.c\\n+++ b/src/backend/access/transam/xlogfuncs.c\\n@@ -26,6 +26,7 @@\\n #include \\\"funcapi.h\\\"\\n #include \\\"miscadmin.h\\\"\\n #include \\\"pgstat.h\\\"\\n+#include \\\"postmaster/bgwriter.h\\\"\\n #include \\\"replication/walreceiver.h\\\"\\n #include \\\"storage/fd.h\\\"\\n #include \\\"storage/ipc.h\\\"\\n@@ -53,6 +54,7 @@ pg_checkpoint(PG_FUNCTION_ARGS)\\n {\\n RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT |\\n (RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));\\n+ PG_RETURN_VOID();\\n }\\n\\n--\\nDaniel Gustafsson\\t\\thttps://vmware.com/\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 3 Nov 2021 15:02:20 +0100\",\n \"msg_from\": \"Daniel Gustafsson <daniel@yesql.se>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Bossart, Nathan (bossartn@amazon.com) wrote:\\n> On 11/2/21, 11:27 AM, \\\"Stephen Frost\\\" <sfrost@snowman.net> wrote:\\n> > * Bossart, Nathan (bossartn@amazon.com) wrote:\\n> >> The approach in the patch looks alright to me, but another one could\\n> >> be to build a SelectStmt when parsing CHECKPOINT. I think that'd\\n> >> simplify the standard_ProcessUtility() changes.\\n> >\\n> > For my 2c, at least, I'm not really partial to either approach, though\\n> > I'd want to see what error messages end up looking like. Seems like we\\n> > might want to exercise a bit more control than we'd be able to if we\\n> > transformed it directly into a SelectStmt (that is, we might add a HINT:\\n> > roles with execute rights on pg_checkpoint() can run this command, or\\n> > something; maybe not too tho).\\n> \\n> I don't feel strongly one way or the other as well, but you have a\\n> good point about extra control over the error messages. The latest\\n> patch just does a standard aclcheck_error(), so you'd probably see\\n> \\\"permission denied for function\\\" if you didn't have privileges for\\n> CHECKPOINT. That could be confusing.\\n\\nYeah, that's exactly the thing I was thinking about that might seem odd.\\nI don't think it's a huge deal but I do think it'd be good for us to at\\nleast think about if we're ok with that or if we want to try and do\\nsomething a bit better.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Wed, 3 Nov 2021 14:46:07 -0400\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-11-02 at 14:26 -0400, Stephen Frost wrote:\\n> Think you meant 'Stephen' there. ;)\\n\\nYes ;-)\\n\\n> > The approach in the patch looks alright to me, but another one\\n> > could\\n> > be to build a SelectStmt when parsing CHECKPOINT. I think that'd\\n> > simplify the standard_ProcessUtility() changes.\\n\\nNathan, if I understand correctly, that would mean no CheckPointStmt at\\nall. So it would either lack the right command tag, or we would have to\\nhack it in somewhere. The utility changes in the existing patch are\\nfairly minor, so I'll stick with that approach unless I'm missing\\nsomething.\\n\\n> For my 2c, at least, I'm not really partial to either approach,\\n> though\\n> I'd want to see what error messages end up looking like. Seems like\\n> we\\n> might want to exercise a bit more control than we'd be able to if we\\n> transformed it directly into a SelectStmt (that is, we might add a\\n> HINT:\\n> roles with execute rights on pg_checkpoint() can run this command, or\\n> something; maybe not too tho).\\n\\nI changed the error message to:\\n\\n ERROR: permission denied for command CHECKPOINT\\n HINT: The CHECKPOINT command requires the EXECUTE privilege\\n on the function pg_checkpoint().\\n\\nNew version attached.\\n\\nAndres suggested that I also consider a new form of the GRANT clause\\nthat works on the CHECKPOINT command directly. I looked into that\\nbriefly, but in every other case it seems that GRANT works on an object\\n(like a function). It doesn't feel like grating on a command is the\\nright solution.\\n\\nThe approach of using a function's ACL to represent the ACL of a\\nhigher-level command (as in this patch) does feel right to me. It feels\\nlike something we might extend to similar situations in the future; and\\neven if we don't, it seems like a clean solution in isolation.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Thu, 04 Nov 2021 09:03:52 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 4, 2021 at 12:03 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> The approach of using a function's ACL to represent the ACL of a\\n> higher-level command (as in this patch) does feel right to me. It feels\\n> like something we might extend to similar situations in the future; and\\n> even if we don't, it seems like a clean solution in isolation.\\n\\nIt feels wrong to me. I realize that it's convenient to be able to\\nre-use the existing GRANT and REVOKE commands that we have for\\nfunctions, but actually DDL interfaces are better than SQL functions,\\nbecause the syntax can be richer and you can avoid things like needing\\nto take a snapshot. This particular patch dodges that problem, which\\nis both a good thing and also clever, but it doesn't really make me\\nfeel any better about the concept in general.\\n\\nI think that the ongoing pressure to reduce as many things as possible\\nto function permissions checks is ultimately going to turn out to be\\nan unpleasant dead end. But by the time we reach that dead end we'll\\nhave put so much effort into making it work that it will be hard to\\nchange course, for backward-compatibility reasons among others.\\n\\nI don't have anything specific to propose, which I realize is kind of\\nunhelpful ... but I don't like this, either.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 4 Nov 2021 12:37:13 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\\n> I don't have anything specific to propose, which I realize is kind of\\n> unhelpful ... but I don't like this, either.\\n\\nWe can go back to having a pg_checkpoint predefined role that is only\\nused for the CHECKPOINT command.\\n\\nThe only real argument against that was a general sense of clutter, but\\nI wasn't entirely convinced of that. If we have a specialized command,\\nwe have all kinds of clutter associated with that; a predefined role\\ndoesn't add much additional clutter.\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 04 Nov 2021 14:25:54 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-11-02 10:28:39 -0700, Jeff Davis wrote:\\n> On Mon, 2021-11-01 at 12:50 -0400, Stephen Frost wrote:\\n> > All that said, I wonder if we can have our cake and eat it too. I\\n> > haven't looked into this at all yet and perhaps it's foolish on its\\n> > face, but, could we make CHECKPOINT; basically turn around and just\\n> > run\\n> > select pg_checkpoint(); with the regular privilege checking\\n> > happening?\\n> > Then we'd keep the existing syntax working, but if the user is\\n> > allowed\\n> > to run the command would depend on if they've been GRANT'd EXECUTE\\n> > rights on the function or not.\\n> \\n> Great idea! Patch attached.\\n> \\n> This feels like a good pattern that we might want to use elsewhere, if\\n> the need arises.\\n> \\t\\tcase T_CheckPointStmt:\\n> -\\t\\t\\tif (!superuser())\\n> -\\t\\t\\t\\tereport(ERROR,\\n> -\\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n> -\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser to do CHECKPOINT\\\")));\\n> +\\t\\t\\t{\\n> +\\t\\t\\t\\t/*\\n> +\\t\\t\\t\\t * Invoke pg_checkpoint(). Implementing the CHECKPOINT command\\n> +\\t\\t\\t\\t * with a function allows administrators to grant privileges\\n> +\\t\\t\\t\\t * on the CHECKPOINT command by granting privileges on the\\n> +\\t\\t\\t\\t * pg_checkpoint() function. It also calls the function\\n> +\\t\\t\\t\\t * execute hook, if present.\\n> +\\t\\t\\t\\t */\\n> +\\t\\t\\t\\tAclResult\\taclresult;\\n> +\\t\\t\\t\\tFmgrInfo\\tflinfo;\\n> +\\n> +\\t\\t\\t\\taclresult = pg_proc_aclcheck(F_PG_CHECKPOINT, GetUserId(),\\n> +\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t ACL_EXECUTE);\\n> +\\t\\t\\t\\tif (aclresult != ACLCHECK_OK)\\n> +\\t\\t\\t\\t\\taclcheck_error(aclresult, OBJECT_FUNCTION,\\n> +\\t\\t\\t\\t\\t\\t\\t\\t get_func_name(F_PG_CHECKPOINT));\\n> \\n> -\\t\\t\\tRequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT |\\n> -\\t\\t\\t\\t\\t\\t\\t (RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));\\n> +\\t\\t\\t\\tInvokeFunctionExecuteHook(F_PG_CHECKPOINT);\\n> +\\n> +\\t\\t\\t\\tfmgr_info(F_PG_CHECKPOINT, &flinfo);\\n> +\\n> +\\t\\t\\t\\t(void) FunctionCall0Coll(&flinfo, InvalidOid);\\n> +\\t\\t\\t}\\n> \\t\\t\\tbreak;\\n\\nI don't like this. This turns the checkpoint command which previously didn't\\nrely on the catalog in the happy path etc into something that requires most of\\nthe backend to be happily up to work.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 4 Nov 2021 15:42:04 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-11-04 14:25:54 -0700, Jeff Davis wrote:\\n> On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\\n> > I don't have anything specific to propose, which I realize is kind of\\n> > unhelpful ... but I don't like this, either.\\n> \\n> We can go back to having a pg_checkpoint predefined role that is only\\n> used for the CHECKPOINT command.\\n\\nWhat about extending GRANT to allow to grant rights on commands? Yes, it'd be\\na bit of work to make that work in the catalogs, but it doesn't seem too hard\\nto tackle.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 4 Nov 2021 15:46:36 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, 2021-11-04 at 15:46 -0700, Andres Freund wrote:\\n> What about extending GRANT to allow to grant rights on commands? Yes,\\n> it'd be\\n> a bit of work to make that work in the catalogs, but it doesn't seem\\n> too hard\\n> to tackle.\\n\\nYou mean for the CHECKPOINT command specifically, or for many commands?\\n\\nIf it only applies to CHECKPOINT, it seems like more net clutter than a\\nnew predefined role.\\n\\nBut I don't see it generalizing to a lot of commands, either. I looked\\nat the list, and it's taking some creativity to think of more than a\\ncouple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\\neven then, there are three related commands: LISTEN, UNLISTEN, and\\nNOTIFY. Are those one privilege representing them all, two\\n(LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 04 Nov 2021 16:35:02 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, 2021-11-04 at 15:42 -0700, Andres Freund wrote:\\n> I don't like this. This turns the checkpoint command which previously\\n> didn't\\n> rely on the catalog in the happy path etc into something that\\n> requires most of\\n> the backend to be happily up to work.\\n\\nIt seems like this specific approach has been mostly shot down already.\\n But out of curiosity, are you intending to run CHECKPOINT during\\nbootstrap or something?\\n\\nRegards,\\n\\tJeff Davis\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Thu, 04 Nov 2021 16:38:36 -0700\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 4, 2021 at 5:25 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> On Thu, 2021-11-04 at 12:37 -0400, Robert Haas wrote:\\n> > I don't have anything specific to propose, which I realize is kind of\\n> > unhelpful ... but I don't like this, either.\\n>\\n> We can go back to having a pg_checkpoint predefined role that is only\\n> used for the CHECKPOINT command.\\n\\nI would prefer that approach. Other people may prefer other things,\\nbut if I got to pick, I'd say do it that way.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 5 Nov 2021 08:40:27 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> It seems like this specific approach has been mostly shot down already.\\n> But out of curiosity, are you intending to run CHECKPOINT during\\n> bootstrap or something?\\n\\nImagine a system with corruption in pg_proc. Right now, that won't\\nprevent you from successfully executing a checkpoint. With this\\napproach, it might.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 5 Nov 2021 08:42:58 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\\n> What about extending GRANT to allow to grant rights on commands? Yes, it'd be\\n> a bit of work to make that work in the catalogs, but it doesn't seem too hard\\n> to tackle.\\n\\nI think that there aren't too many commands where the question is just\\nwhether you can execute the command or not. CHECKPOINT is one that\\ndoes work that way, but if it's VACUUM or ANALYZE the question will be\\nwhether you can run it on a particular table; if it's ALTER SYSTEM it\\nwill be whether you can run it for that GUC; and so on. CHECKPOINT is\\none of the few commands that has no target.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 5 Nov 2021 08:54:37 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 2021-Nov-04, Jeff Davis wrote:\\n\\n> But I don't see it generalizing to a lot of commands, either. I looked\\n> at the list, and it's taking some creativity to think of more than a\\n> couple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\\n> even then, there are three related commands: LISTEN, UNLISTEN, and\\n> NOTIFY. Are those one privilege representing them all, two\\n> (LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\\n\\nWhat about things like CREATE SUBSCRIPTION/PUBLICATION? Sounds like it\\nwould be useful to allow non-superusers do those, too.\\n\\nThat said, if the list is short, then additional predefined roles seem\\npreferrable to having a ton of infrastructure code that might be much\\nmore clutter than what seems a short list of additional predefined roles.\\n\\n-- \\nÁlvaro Herrera 39°49'30\\\"S 73°17'W — https://www.EnterpriseDB.com/\\n\\\"We're here to devour each other alive\\\" (Hobbes)\\n\\n\\n\",\n \"msg_date\": \"Fri, 5 Nov 2021 10:13:11 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 2021-11-05 08:42:58 -0400, Robert Haas wrote:\\n> On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > It seems like this specific approach has been mostly shot down already.\\n> > But out of curiosity, are you intending to run CHECKPOINT during\\n> > bootstrap or something?\\n> \\n> Imagine a system with corruption in pg_proc. Right now, that won't\\n> prevent you from successfully executing a checkpoint. With this\\n> approach, it might.\\n\\nExactly. It wouldn't matter if checkpoints weren't something needed to\\npotentially bring the system back into a sane state, but ...\\n\\n\\n\",\n \"msg_date\": \"Sun, 7 Nov 2021 10:46:49 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-11-05 08:54:37 -0400, Robert Haas wrote:\\n> On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\\n> > What about extending GRANT to allow to grant rights on commands? Yes, it'd be\\n> > a bit of work to make that work in the catalogs, but it doesn't seem too hard\\n> > to tackle.\\n> \\n> I think that there aren't too many commands where the question is just\\n> whether you can execute the command or not. CHECKPOINT is one that\\n> does work that way, but if it's VACUUM or ANALYZE the question will be\\n> whether you can run it on a particular table; if it's ALTER SYSTEM it\\n> will be whether you can run it for that GUC; and so on. CHECKPOINT is\\n> one of the few commands that has no target.\\n\\nI don't know if that's really such a big deal. It's useful to be able to grant\\nthe right to do a system wide ANALYZE etc to a role that can't otherwise do\\nanything with the table. Even for ALTER SYSTEM etc it seems like it'd be\\nhelpful, because it allows to constrain an admin tool to \\\"legitimate\\\" admin\\npaths, without allowing, say, UPDATE pg_proc.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Sun, 7 Nov 2021 10:50:49 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Andres Freund (andres@anarazel.de) wrote:\\n> On 2021-11-05 08:42:58 -0400, Robert Haas wrote:\\n> > On Thu, Nov 4, 2021 at 7:38 PM Jeff Davis <pgsql@j-davis.com> wrote:\\n> > > It seems like this specific approach has been mostly shot down already.\\n> > > But out of curiosity, are you intending to run CHECKPOINT during\\n> > > bootstrap or something?\\n> > \\n> > Imagine a system with corruption in pg_proc. Right now, that won't\\n> > prevent you from successfully executing a checkpoint. With this\\n> > approach, it might.\\n> \\n> Exactly. It wouldn't matter if checkpoints weren't something needed to\\n> potentially bring the system back into a sane state, but ...\\n\\nThis really isn't that hard to address- do a superuser check, if it\\npasses then just call the checkpoint function like CHECKPOINT; does\\ntoday. Otherwise, check the perms on the function or just call the\\nfunction in a manner which would check privileges, or maybe have another\\npredefined role, though I continue to feel like the function based\\napproach is better.\\n\\nIf we're actually worried about catalog corruption (and, frankly, I've\\ngot some serious doubts that jumping in and running CHECKPOINT; by hand\\nis a great idea if there's such active corruption) then we must use such\\nan approach no matter how we allow non-superusers to run the command\\nbecause any approach to that necessarily involves some amount of catalog\\naccess.\\n\\nAny concern leveraged against pg_proc applies equally to pg_auth_members\\nafter all, so having it be something role-based vs. function privilege\\nis really just moving deck chairs around on the titanic at that point.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 12:23:18 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Andres Freund (andres@anarazel.de) wrote:\\n> On 2021-11-05 08:54:37 -0400, Robert Haas wrote:\\n> > On Thu, Nov 4, 2021 at 6:46 PM Andres Freund <andres@anarazel.de> wrote:\\n> > > What about extending GRANT to allow to grant rights on commands? Yes, it'd be\\n> > > a bit of work to make that work in the catalogs, but it doesn't seem too hard\\n> > > to tackle.\\n> > \\n> > I think that there aren't too many commands where the question is just\\n> > whether you can execute the command or not. CHECKPOINT is one that\\n> > does work that way, but if it's VACUUM or ANALYZE the question will be\\n> > whether you can run it on a particular table; if it's ALTER SYSTEM it\\n> > will be whether you can run it for that GUC; and so on. CHECKPOINT is\\n> > one of the few commands that has no target.\\n> \\n> I don't know if that's really such a big deal. It's useful to be able to grant\\n> the right to do a system wide ANALYZE etc to a role that can't otherwise do\\n> anything with the table. Even for ALTER SYSTEM etc it seems like it'd be\\n> helpful, because it allows to constrain an admin tool to \\\"legitimate\\\" admin\\n> paths, without allowing, say, UPDATE pg_proc.\\n\\nNote that it's already possible to have a non-superuser who can run\\nVACUUM and ANALYZE on all non-shared tables in a database but who\\notherwise isn't able to mess with the tables owned by other users- that\\nis something the database owner can do.\\n\\nPerhaps it's useful to break that out into a separately grantable\\npermission but the argument should really by why you'd want to GRANT\\nsomeone the ability to VACUUM/ANALYZE an entire database while *not*\\nhaving them be the database owner. That's a much more narrow use-case\\nvs. having them not be a superuser or be able to do things like UPDATE\\npg_proc.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 12:32:38 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-11-08 12:23:18 -0500, Stephen Frost wrote:\\n> If we're actually worried about catalog corruption (and, frankly, I've\\n> got some serious doubts that jumping in and running CHECKPOINT; by hand\\n> is a great idea if there's such active corruption)\\n\\nI've been there when recovering from corruption.\\n\\n\\n> though I continue to feel like the function based approach is better.\\n\\nI think it's a somewhat ugly hack.\\n\\n\\n> then we must use such an approach no matter how we allow non-superusers to\\n> run the command because any approach to that necessarily involves some\\n> amount of catalog access.\\n\\nAs long as there's no additional catalog access when the user is known to be a\\nsuperuser, then I think it's fine. There's a difference between doing one\\npg_authid read for superuser - with a fallback to automatically assuming a\\nuser if one couldn't be found - and doing a full pg_proc read with several\\nsubsidiary pg_type reads etc.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Nov 2021 09:33:25 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\\n> On 2021-Nov-04, Jeff Davis wrote:\\n> > But I don't see it generalizing to a lot of commands, either. I looked\\n> > at the list, and it's taking some creativity to think of more than a\\n> > couple other commands where it makes sense. Maybe LISTEN/NOTIFY? But\\n> > even then, there are three related commands: LISTEN, UNLISTEN, and\\n> > NOTIFY. Are those one privilege representing them all, two\\n> > (LISTEN/UNLISTEN, and NOTIFY), or three separate privileges?\\n> \\n> What about things like CREATE SUBSCRIPTION/PUBLICATION? Sounds like it\\n> would be useful to allow non-superusers do those, too.\\n\\nAgreed. Having these be limited to superusers is unfortunate, though at\\nthe time probably made sense as otherwise it would have made it that\\nmuch more difficult to get logical replication in. Now is a great time\\nto try and improve on that situation though. This is a bit tricky\\nthough since creating a subscription means that you'll be able to cause\\nsome code to be executed with higher privileges today, as I recall, and\\nwe'd need to make sure to address that. If we can make sure that a\\nsubscription isn't able to be used to execute code as effectively a\\nsuperuser then I would think the other permission needed to create one,\\nfor tables which you own, would be just a \\\"network access\\\" kind of\\ncapability. In other words, I'm not 100% sure we need to have 'create\\nsubscription' require different privileges from 'create a foreign\\nserver'. Then again, having additional predefined rules isn't a huge\\ncost and perhaps it would be better to avoid the confusion that\\nintroducing a separate 'capabilities' kind of system would involve where\\nthose capabilities cross multiple commands.\\n\\n> That said, if the list is short, then additional predefined roles seem\\n> preferrable to having a ton of infrastructure code that might be much\\n> more clutter than what seems a short list of additional predefined roles.\\n\\nNone of this strikes me as a 'ton of infrastructure code' and so I'm not\\nquite sure I'm following the argument being made here.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 12:39:33 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On 2021-Nov-08, Stephen Frost wrote:\\n\\n> * Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\\n\\n> > That said, if the list is short, then additional predefined roles seem\\n> > preferrable to having a ton of infrastructure code that might be much\\n> > more clutter than what seems a short list of additional predefined roles.\\n> \\n> None of this strikes me as a 'ton of infrastructure code' and so I'm not\\n> quite sure I'm following the argument being made here.\\n\\nI was referring specifically to Andres' idea of having additional DDL\\ncommands handled as special GRANTable privileges, \\nhttps://postgr.es/m/20211104224636.5qg6cfyjkw52rh4d@alap3.anarazel.de\\n\\n-- \\nÁlvaro Herrera Valdivia, Chile — https://www.EnterpriseDB.com/\\n\\\"Hay quien adquiere la mala costumbre de ser infeliz\\\" (M. A. Evans)\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Nov 2021 14:45:20 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Andres Freund (andres@anarazel.de) wrote:\\n> On 2021-11-08 12:23:18 -0500, Stephen Frost wrote:\\n> > though I continue to feel like the function based approach is better.\\n> \\n> I think it's a somewhat ugly hack.\\n\\nI suppose we'll just have to disagree on that. :)\\n\\nI don't feel as strongly as others apparently do on this point though,\\nand I'd rather have non-superusers able to run CHECKPOINT *somehow*\\nthan not, so if the others feel like a predefined role is a better\\napproach then I'm alright with that. Seems a bit overkill to me but\\nit's also not like it's actually all that much code or work to do.\\n\\n> > then we must use such an approach no matter how we allow non-superusers to\\n> > run the command because any approach to that necessarily involves some\\n> > amount of catalog access.\\n> \\n> As long as there's no additional catalog access when the user is known to be a\\n> superuser, then I think it's fine. There's a difference between doing one\\n> pg_authid read for superuser - with a fallback to automatically assuming a\\n> user if one couldn't be found - and doing a full pg_proc read with several\\n> subsidiary pg_type reads etc.\\n\\nYes, the approach I'm suggesting would make the superuser-run CHECKPOINT\\nbe exactly the same as it is today, while a non-superuser trying to run\\na CHECKPOINT would end up doing additional catalog accesses.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 12:47:23 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\\n> On 2021-Nov-08, Stephen Frost wrote:\\n> \\n> > * Alvaro Herrera (alvherre@alvh.no-ip.org) wrote:\\n> \\n> > > That said, if the list is short, then additional predefined roles seem\\n> > > preferrable to having a ton of infrastructure code that might be much\\n> > > more clutter than what seems a short list of additional predefined roles.\\n> > \\n> > None of this strikes me as a 'ton of infrastructure code' and so I'm not\\n> > quite sure I'm following the argument being made here.\\n> \\n> I was referring specifically to Andres' idea of having additional DDL\\n> commands handled as special GRANTable privileges, \\n> https://postgr.es/m/20211104224636.5qg6cfyjkw52rh4d@alap3.anarazel.de\\n\\nAh, thanks, I had seen that but didn't quite associate it to this\\ncomment.\\n\\nPerhaps not a surprise, but I tend to favor predefined roles for these\\nkinds of things. If we do want to revamp how GRANT works, I'd argue for\\nfirst splitting up the way we handle privileges to be on a\\nper-object-type basis and once we did that then we could extend that to\\nallow GRANT on commands more easily (and with more variety as to what\\nprivileges a GRANT on a command could be). It's kind of cute to have\\none bitmap covering all objects but it puts us into a place where\\nextending what can be GRANT'd on one kind of object necessarily impacts\\nour ability to GRANT on other kinds (eg: we have a bit reserved for\\nTRUNCATE in the same bitmask for a schema as we do for a table, but we\\ndon't allow TRUNCATE on schemas and probably never will).\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 12:53:44 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Isaac Morland (isaac.morland@gmail.com) wrote:\\n> On Tue, 2 Nov 2021 at 19:00, Vik Fearing <vik@postgresfriends.org> wrote:\\n> > On 11/2/21 11:14 PM, Vik Fearing wrote:\\n> >\\n> > > This would be nice, but there is nothing to hang our hat on:\\n> > >\\n> > > GRANT CHECKPOINT TO username;\\n> >\\n> > Thinking about this more, why don't we just add CHECKPOINT and\\n> > NOCHECKPOINT attributes to roles?\\n> >\\n> > ALTER ROLE username WITH CHECKPOINT;\\n> \\n> At present, this would require adding a field to pg_authid. This isn't very\\n> scalable; but we're already creating new pg_* roles which give access to\\n> various actions so I don't know why a role attribute would be a better\\n> approach. If anything, I think it would be more likely to move in the other\\n> direction: replace role attributes that in effect grant privileges with\\n> predefined roles. I think this has already been discussed here in the\\n> context of CREATEROLE.\\n\\nYes, much better to create predefined roles for this kind of thing and,\\nideally, move explicitly away from role attributes.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 14:11:57 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-08 at 12:47 -0500, Stephen Frost wrote:\\n> \\n> I don't feel as strongly as others apparently do on this point\\n> though,\\n> and I'd rather have non-superusers able to run CHECKPOINT *somehow*\\n> than not, so if the others feel like a predefined role is a better\\n> approach then I'm alright with that. Seems a bit overkill to me but\\n> it's also not like it's actually all that much code or work to do.\\n\\n+1. It seems like the pg_checkpointer predefined role is the most\\nacceptable to everyone (even if not universally liked).\\n\\nAttached a rebased version of that patch.\\n\\nRegards,\\n\\tJeff Davis\",\n \"msg_date\": \"Mon, 08 Nov 2021 16:13:17 -0800\",\n \"msg_from\": \"Jeff Davis <pgsql@j-davis.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jeff Davis (pgsql@j-davis.com) wrote:\\n> On Mon, 2021-11-08 at 12:47 -0500, Stephen Frost wrote:\\n> > \\n> > I don't feel as strongly as others apparently do on this point\\n> > though,\\n> > and I'd rather have non-superusers able to run CHECKPOINT *somehow*\\n> > than not, so if the others feel like a predefined role is a better\\n> > approach then I'm alright with that. Seems a bit overkill to me but\\n> > it's also not like it's actually all that much code or work to do.\\n> \\n> +1. It seems like the pg_checkpointer predefined role is the most\\n> acceptable to everyone (even if not universally liked).\\n> \\n> Attached a rebased version of that patch.\\n\\nThanks. Quick review-\\n\\n> diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c\\n> index bf085aa93b2..0ff832a62c2 100644\\n> --- a/src/backend/tcop/utility.c\\n> +++ b/src/backend/tcop/utility.c\\n> @@ -24,6 +24,7 @@\\n> #include \\\"catalog/catalog.h\\\"\\n> #include \\\"catalog/index.h\\\"\\n> #include \\\"catalog/namespace.h\\\"\\n> +#include \\\"catalog/pg_authid.h\\\"\\n> #include \\\"catalog/pg_inherits.h\\\"\\n> #include \\\"catalog/toasting.h\\\"\\n> #include \\\"commands/alter.h\\\"\\n> @@ -939,10 +940,10 @@ standard_ProcessUtility(PlannedStmt *pstmt,\\n> \\t\\t\\tbreak;\\n> \\n> \\t\\tcase T_CheckPointStmt:\\n> -\\t\\t\\tif (!superuser())\\n> +\\t\\t\\tif (!has_privs_of_role(GetUserId(), ROLE_PG_CHECKPOINTER))\\n> \\t\\t\\t\\tereport(ERROR,\\n> \\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n> -\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser to do CHECKPOINT\\\")));\\n> +\\t\\t\\t\\t\\t\\t errmsg(\\\"must be member of pg_checkpointer to do CHECKPOINT\\\")));\\n\\nMost such error messages say 'superuser or '... Also, note the recent\\nthread about trying to ensure that places are using has_privs_of_role()\\nas you're doing here but also say that in the error message\\nconsistently, rather than 'member of' it should really be 'has\\nprivileges of' as the two are not necessarily always the same. You can\\nbe a member of a role but not actively have the privileges of that role.\\n\\nOtherwise, looks pretty good to me. I'll note that has_privs_of_role()\\nwill first call superuser_arg(member), just the same as the prior\\nsuperuser() check did, so this doesn't change the catalog accesses in\\nthat case from today.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Tue, 9 Nov 2021 11:29:38 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Predefined role pg_maintenance for VACUUM, ANALYZE, CHECKPOINT.\"\n }\n]","isConversational":false}}},{"rowIdx":52989,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n\nCIC and REINDEX CONCURRENTLY assume backends see their catalog changes\nno later than each backend's next transaction start. That failed to\nhold when a backend absorbed a relevant invalidation in the middle of\nrunning RelationBuildDesc() on the CIC index. Queries that use the\nresulting index can silently fail to find rows. Fix this for future\nindex builds by making RelationBuildDesc() loop until it finishes\nwithout accepting a relevant invalidation. It may be necessary to\nreindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\nBack-patch to 9.6 (all supported versions).\n\nNoah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\nFreund.\n\nDiscussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n\nBranch\n------\nmaster\n\nDetails\n-------\nhttps://git.postgresql.org/pg/commitdiff/fdd965d074d46765c295223b119ca437dbcac973\n\nModified Files\n--------------\ncontrib/amcheck/t/002_cic.pl | 78 ++++++++++++++++\nsrc/backend/utils/cache/inval.c | 12 ++-\nsrc/backend/utils/cache/relcache.c | 115 +++++++++++++++++++++--\nsrc/bin/pgbench/t/001_pgbench_with_server.pl | 118 +++++++----------------\nsrc/include/utils/inval.h | 1 +\nsrc/include/utils/relcache.h | 2 +-\nsrc/test/perl/PostgresNode.pm | 134 +++++++++++++++++++++++++++\nsrc/tools/pgindent/typedefs.list | 1 +\n8 files changed, 368 insertions(+), 93 deletions(-)","msg_date":"Sun, 24 Oct 2021 01:40:12 +0000","msg_from":"Noah Misch <noah@leadboat.com>","msg_from_op":true,"msg_subject":"pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On 10/24/21 03:40, Noah Misch wrote:\n> Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n> \n> CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\n> no later than each backend's next transaction start. That failed to\n> hold when a backend absorbed a relevant invalidation in the middle of\n> running RelationBuildDesc() on the CIC index. Queries that use the\n> resulting index can silently fail to find rows. Fix this for future\n> index builds by making RelationBuildDesc() loop until it finishes\n> without accepting a relevant invalidation. It may be necessary to\n> reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\n> Back-patch to 9.6 (all supported versions).\n> \n> Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\n> Freund.\n> \n> Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n> \n\nUnfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. \nSince this commit, initdb never completes due to infinite retrying over \nand over (on the first RelationBuildDesc call).\n\nWe have a CLOBBER_CACHE_ALWAYS buildfarm machine \"avocet\", and that \ncurrently looks like this (top):\n\n PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ \nCOMMAND\n 2626 buildfa+ 20 0 202888 21416 20084 R 98.34 0.531 151507:16 \n/home/buildfarm/avocet/buildroot/REL9_6_STABLE/pgsql.build/tmp_install/home/buildfarm/avocet/buildroot/REL9_6_STABLE/inst/bin/postgres \n--boot -x1 -F\n\nYep, that's 151507 minutes, i.e. 104 days in initdb :-/\n\n\nI haven't looked at this very closely yet, but it seems the whole \nproblem is we do this at the very beginning:\n\n in_progress_list[in_progress_offset].invalidated = false;\n\n /*\n * find the tuple in pg_class corresponding to the given relation id\n */\n pg_class_tuple = ScanPgRelation(targetRelId, true, false);\n\nwhich seems entirely self-defeating, because ScanPgRelation acquires a \nlock (on pg_class), which accepts invalidations, which invalidates \nsystem caches (in clobber_cache_always), which sets promptly sets\n\n in_progress_list[in_progress_offset].invalidated = false;\n\nguaranteeing an infinite loop.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Tue, 8 Feb 2022 22:13:01 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"Hi,\n\nOn 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\n> On 10/24/21 03:40, Noah Misch wrote:\n> > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n> > \n> > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\n> > no later than each backend's next transaction start. That failed to\n> > hold when a backend absorbed a relevant invalidation in the middle of\n> > running RelationBuildDesc() on the CIC index. Queries that use the\n> > resulting index can silently fail to find rows. Fix this for future\n> > index builds by making RelationBuildDesc() loop until it finishes\n> > without accepting a relevant invalidation. It may be necessary to\n> > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\n> > Back-patch to 9.6 (all supported versions).\n> > \n> > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\n> > Freund.\n> > \n> > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n> > \n> \n> Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\n> this commit, initdb never completes due to infinite retrying over and over\n> (on the first RelationBuildDesc call).\n\nUgh. Do we need to do something about WRT the next set of minor releases? Is\nthere a a chance of this occuring in \"real\" workloads?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 8 Feb 2022 16:43:47 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\n> Ugh. Do we need to do something about WRT the next set of minor\n> releases?\n\nThe set of minor releases of this week has already been stamped, so\nthat's too late :/\n\n> Is there a a chance of this occuring in \"real\" workloads?\n\nUgh++. The problem is that we would not really detect that\nautomatically, isn't it?\n--\nMichael","msg_date":"Wed, 9 Feb 2022 10:23:06 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"\n\nOn 2/9/22 01:43, Andres Freund wrote:\n> Hi,\n> \n> On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\n>> On 10/24/21 03:40, Noah Misch wrote:\n>>> Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n>>>\n>>> CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\n>>> no later than each backend's next transaction start. That failed to\n>>> hold when a backend absorbed a relevant invalidation in the middle of\n>>> running RelationBuildDesc() on the CIC index. Queries that use the\n>>> resulting index can silently fail to find rows. Fix this for future\n>>> index builds by making RelationBuildDesc() loop until it finishes\n>>> without accepting a relevant invalidation. It may be necessary to\n>>> reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\n>>> Back-patch to 9.6 (all supported versions).\n>>>\n>>> Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\n>>> Freund.\n>>>\n>>> Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n>>>\n>>\n>> Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\n>> this commit, initdb never completes due to infinite retrying over and over\n>> (on the first RelationBuildDesc call).\n> \n> Ugh. Do we need to do something about WRT the next set of minor releases? Is\n> there a a chance of this occuring in \"real\" workloads?\n> \n\nAFAICS this only affects builds with CLOBBER_CACHE_ALWAYS, and anyone \nrunning such build in production clearly likes painful things anyway.\n\nBut really, for the infinite loop to happen, building a relation \ndescriptor has to invalidate a cache. And I haven't found a way to do \nthat without the CLOBBER_CACHE_ALWAYS thing.\n\nAlso, all the November minor releases include this commit, and there \nwere no reports about this (pretty obvious) issue. Buildfarm did not \ncomplain either (but an animal may be stuck for months and we would not \nknow about it).\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Wed, 9 Feb 2022 02:25:09 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"Hi,\n\nOn 2022-02-09 10:23:06 +0900, Michael Paquier wrote:\n> On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\n> > Ugh. Do we need to do something about WRT the next set of minor\n> > releases?\n> \n> The set of minor releases of this week has already been stamped, so\n> that's too late :/\n\nIt's stamped, not tagged, so we could send out new tarballs. Or we could skip\na release number. IIRC we had to do something along those lines before.\n\n\n> Ugh++. The problem is that we would not really detect that\n> automatically, isn't it?\n\nWhat do you mean with detect here?\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 8 Feb 2022 17:43:34 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"Hi,\n\nOn 2022-02-09 02:25:09 +0100, Tomas Vondra wrote:\n> AFAICS this only affects builds with CLOBBER_CACHE_ALWAYS, and anyone\n> running such build in production clearly likes painful things anyway.\n\nYea, realistically nobody does that.\n\n\n> But really, for the infinite loop to happen, building a relation descriptor\n> has to invalidate a cache. And I haven't found a way to do that without the\n> CLOBBER_CACHE_ALWAYS thing.\n\nPhew.\n\n\n> Also, all the November minor releases include this commit, and there were no\n> reports about this (pretty obvious) issue. Buildfarm did not complain either\n> (but an animal may be stuck for months and we would not know about it).\n\nAh, somehow I thought that wasn't yet in the last set of releases. Phew #2.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 8 Feb 2022 17:53:59 -0800","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\n> On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\n> > On 10/24/21 03:40, Noah Misch wrote:\n> > > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n> > > \n> > > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\n> > > no later than each backend's next transaction start. That failed to\n> > > hold when a backend absorbed a relevant invalidation in the middle of\n> > > running RelationBuildDesc() on the CIC index. Queries that use the\n> > > resulting index can silently fail to find rows. Fix this for future\n> > > index builds by making RelationBuildDesc() loop until it finishes\n> > > without accepting a relevant invalidation. It may be necessary to\n> > > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\n> > > Back-patch to 9.6 (all supported versions).\n> > > \n> > > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\n> > > Freund.\n> > > \n> > > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n> > > \n> > \n> > Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\n> > this commit, initdb never completes due to infinite retrying over and over\n> > (on the first RelationBuildDesc call).\n\nThanks for the report. I had added the debug_discard arguments of\nInvalidateSystemCachesExtended() and RelationCacheInvalidate() to make the new\ncode survive a CREATE TABLE at debug_discard_caches=5. Apparently that's not\nenough for initdb. I'll queue a task to look at it.\n\nIt's a good reminder to set wait_timeout on buildfarm animals. (I should take\nthat advice, too.)\n\n> Ugh. Do we need to do something about WRT the next set of minor releases?\n\nNo, given that this code already debuted in the November releases.\n\n\n","msg_date":"Tue, 8 Feb 2022 18:04:03 -0800","msg_from":"Noah Misch <noah@leadboat.com>","msg_from_op":true,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On Tue, Feb 08, 2022 at 05:43:34PM -0800, Andres Freund wrote:\n> It's stamped, not tagged, so we could send out new tarballs. Or we could skip\n> a release number. IIRC we had to do something along those lines before.\n\nIt does not matter now, but the release is stamped and tagged.\n\n> What do you mean with detect here?\n\nWell, we would not be able to see that something is stuck by default,\nbut Noah has just answered to my question by mentioning wait_timeout\nin the buildfarm configuration.\n--\nMichael","msg_date":"Wed, 9 Feb 2022 11:24:21 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On Tue, Feb 08, 2022 at 06:04:03PM -0800, Noah Misch wrote:\n> On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\n> > On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\n> > > On 10/24/21 03:40, Noah Misch wrote:\n> > > > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n> > > > \n> > > > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\n> > > > no later than each backend's next transaction start. That failed to\n> > > > hold when a backend absorbed a relevant invalidation in the middle of\n> > > > running RelationBuildDesc() on the CIC index. Queries that use the\n> > > > resulting index can silently fail to find rows. Fix this for future\n> > > > index builds by making RelationBuildDesc() loop until it finishes\n> > > > without accepting a relevant invalidation. It may be necessary to\n> > > > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\n> > > > Back-patch to 9.6 (all supported versions).\n> > > > \n> > > > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\n> > > > Freund.\n> > > > \n> > > > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\n> > > > \n> > > \n> > > Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\n> > > this commit, initdb never completes due to infinite retrying over and over\n> > > (on the first RelationBuildDesc call).\n> \n> Thanks for the report. I had added the debug_discard arguments of\n> InvalidateSystemCachesExtended() and RelationCacheInvalidate() to make the new\n> code survive a CREATE TABLE at debug_discard_caches=5. Apparently that's not\n> enough for initdb. I'll queue a task to look at it.\n\nThe explanation was more boring than that. v13 and earlier have an additional\nInvalidateSystemCaches() call site, which I neglected to update. Here's the\nfix I intend to push.","msg_date":"Tue, 8 Feb 2022 21:41:41 -0800","msg_from":"Noah Misch <noah@leadboat.com>","msg_from_op":true,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"Michael Paquier <michael@paquier.xyz> writes:\n> On Tue, Feb 08, 2022 at 05:43:34PM -0800, Andres Freund wrote:\n>> It's stamped, not tagged, so we could send out new tarballs. Or we could skip\n>> a release number. IIRC we had to do something along those lines before.\n\n> It does not matter now, but the release is stamped and tagged.\n\nYeah, I see no need to do anything about this on an emergency\nbasis.\n\n>> What do you mean with detect here?\n\n> Well, we would not be able to see that something is stuck by default,\n> but Noah has just answered to my question by mentioning wait_timeout\n> in the buildfarm configuration.\n\nThe buildfarm's wait_timeout option isn't that helpful here, because\nwhen it triggers, the client just goes belly-up *with no report*.\nSo even if the CCA animals had it on, you'd not notice unless you\nstarted to wonder why they'd not reported lately.\n\nI think that's a bug that ought to be fixed. I do agree that\nwait_timeout ought to be finite by default, too.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 09 Feb 2022 00:44:42 -0500","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"},{"msg_contents":"On 2/9/22 06:41, Noah Misch wrote:\n>\n> The explanation was more boring than that. v13 and earlier have an additional\n> InvalidateSystemCaches() call site, which I neglected to update. Here's the\n> fix I intend to push.\n\nI tried this patch on 10 and 13, and it seems to fix the issue. So +1.\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Wed, 9 Feb 2022 16:27:39 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\n CONCURR"}],"string":"[\n {\n \"msg_contents\": \"Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n\\nCIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\nno later than each backend's next transaction start. That failed to\\nhold when a backend absorbed a relevant invalidation in the middle of\\nrunning RelationBuildDesc() on the CIC index. Queries that use the\\nresulting index can silently fail to find rows. Fix this for future\\nindex builds by making RelationBuildDesc() loop until it finishes\\nwithout accepting a relevant invalidation. It may be necessary to\\nreindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\nBack-patch to 9.6 (all supported versions).\\n\\nNoah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\nFreund.\\n\\nDiscussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n\\nBranch\\n------\\nmaster\\n\\nDetails\\n-------\\nhttps://git.postgresql.org/pg/commitdiff/fdd965d074d46765c295223b119ca437dbcac973\\n\\nModified Files\\n--------------\\ncontrib/amcheck/t/002_cic.pl | 78 ++++++++++++++++\\nsrc/backend/utils/cache/inval.c | 12 ++-\\nsrc/backend/utils/cache/relcache.c | 115 +++++++++++++++++++++--\\nsrc/bin/pgbench/t/001_pgbench_with_server.pl | 118 +++++++----------------\\nsrc/include/utils/inval.h | 1 +\\nsrc/include/utils/relcache.h | 2 +-\\nsrc/test/perl/PostgresNode.pm | 134 +++++++++++++++++++++++++++\\nsrc/tools/pgindent/typedefs.list | 1 +\\n8 files changed, 368 insertions(+), 93 deletions(-)\",\n \"msg_date\": \"Sun, 24 Oct 2021 01:40:12 +0000\",\n \"msg_from\": \"Noah Misch <noah@leadboat.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On 10/24/21 03:40, Noah Misch wrote:\\n> Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n> \\n> CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\n> no later than each backend's next transaction start. That failed to\\n> hold when a backend absorbed a relevant invalidation in the middle of\\n> running RelationBuildDesc() on the CIC index. Queries that use the\\n> resulting index can silently fail to find rows. Fix this for future\\n> index builds by making RelationBuildDesc() loop until it finishes\\n> without accepting a relevant invalidation. It may be necessary to\\n> reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\n> Back-patch to 9.6 (all supported versions).\\n> \\n> Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\n> Freund.\\n> \\n> Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n> \\n\\nUnfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. \\nSince this commit, initdb never completes due to infinite retrying over \\nand over (on the first RelationBuildDesc call).\\n\\nWe have a CLOBBER_CACHE_ALWAYS buildfarm machine \\\"avocet\\\", and that \\ncurrently looks like this (top):\\n\\n PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ \\nCOMMAND\\n 2626 buildfa+ 20 0 202888 21416 20084 R 98.34 0.531 151507:16 \\n/home/buildfarm/avocet/buildroot/REL9_6_STABLE/pgsql.build/tmp_install/home/buildfarm/avocet/buildroot/REL9_6_STABLE/inst/bin/postgres \\n--boot -x1 -F\\n\\nYep, that's 151507 minutes, i.e. 104 days in initdb :-/\\n\\n\\nI haven't looked at this very closely yet, but it seems the whole \\nproblem is we do this at the very beginning:\\n\\n in_progress_list[in_progress_offset].invalidated = false;\\n\\n /*\\n * find the tuple in pg_class corresponding to the given relation id\\n */\\n pg_class_tuple = ScanPgRelation(targetRelId, true, false);\\n\\nwhich seems entirely self-defeating, because ScanPgRelation acquires a \\nlock (on pg_class), which accepts invalidations, which invalidates \\nsystem caches (in clobber_cache_always), which sets promptly sets\\n\\n in_progress_list[in_progress_offset].invalidated = false;\\n\\nguaranteeing an infinite loop.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Feb 2022 22:13:01 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\\n> On 10/24/21 03:40, Noah Misch wrote:\\n> > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n> > \\n> > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\n> > no later than each backend's next transaction start. That failed to\\n> > hold when a backend absorbed a relevant invalidation in the middle of\\n> > running RelationBuildDesc() on the CIC index. Queries that use the\\n> > resulting index can silently fail to find rows. Fix this for future\\n> > index builds by making RelationBuildDesc() loop until it finishes\\n> > without accepting a relevant invalidation. It may be necessary to\\n> > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\n> > Back-patch to 9.6 (all supported versions).\\n> > \\n> > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\n> > Freund.\\n> > \\n> > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n> > \\n> \\n> Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\\n> this commit, initdb never completes due to infinite retrying over and over\\n> (on the first RelationBuildDesc call).\\n\\nUgh. Do we need to do something about WRT the next set of minor releases? Is\\nthere a a chance of this occuring in \\\"real\\\" workloads?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Feb 2022 16:43:47 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\\n> Ugh. Do we need to do something about WRT the next set of minor\\n> releases?\\n\\nThe set of minor releases of this week has already been stamped, so\\nthat's too late :/\\n\\n> Is there a a chance of this occuring in \\\"real\\\" workloads?\\n\\nUgh++. The problem is that we would not really detect that\\nautomatically, isn't it?\\n--\\nMichael\",\n \"msg_date\": \"Wed, 9 Feb 2022 10:23:06 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 2/9/22 01:43, Andres Freund wrote:\\n> Hi,\\n> \\n> On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\\n>> On 10/24/21 03:40, Noah Misch wrote:\\n>>> Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n>>>\\n>>> CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\n>>> no later than each backend's next transaction start. That failed to\\n>>> hold when a backend absorbed a relevant invalidation in the middle of\\n>>> running RelationBuildDesc() on the CIC index. Queries that use the\\n>>> resulting index can silently fail to find rows. Fix this for future\\n>>> index builds by making RelationBuildDesc() loop until it finishes\\n>>> without accepting a relevant invalidation. It may be necessary to\\n>>> reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\n>>> Back-patch to 9.6 (all supported versions).\\n>>>\\n>>> Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\n>>> Freund.\\n>>>\\n>>> Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n>>>\\n>>\\n>> Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\\n>> this commit, initdb never completes due to infinite retrying over and over\\n>> (on the first RelationBuildDesc call).\\n> \\n> Ugh. Do we need to do something about WRT the next set of minor releases? Is\\n> there a a chance of this occuring in \\\"real\\\" workloads?\\n> \\n\\nAFAICS this only affects builds with CLOBBER_CACHE_ALWAYS, and anyone \\nrunning such build in production clearly likes painful things anyway.\\n\\nBut really, for the infinite loop to happen, building a relation \\ndescriptor has to invalidate a cache. And I haven't found a way to do \\nthat without the CLOBBER_CACHE_ALWAYS thing.\\n\\nAlso, all the November minor releases include this commit, and there \\nwere no reports about this (pretty obvious) issue. Buildfarm did not \\ncomplain either (but an animal may be stuck for months and we would not \\nknow about it).\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Wed, 9 Feb 2022 02:25:09 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-02-09 10:23:06 +0900, Michael Paquier wrote:\\n> On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\\n> > Ugh. Do we need to do something about WRT the next set of minor\\n> > releases?\\n> \\n> The set of minor releases of this week has already been stamped, so\\n> that's too late :/\\n\\nIt's stamped, not tagged, so we could send out new tarballs. Or we could skip\\na release number. IIRC we had to do something along those lines before.\\n\\n\\n> Ugh++. The problem is that we would not really detect that\\n> automatically, isn't it?\\n\\nWhat do you mean with detect here?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Feb 2022 17:43:34 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-02-09 02:25:09 +0100, Tomas Vondra wrote:\\n> AFAICS this only affects builds with CLOBBER_CACHE_ALWAYS, and anyone\\n> running such build in production clearly likes painful things anyway.\\n\\nYea, realistically nobody does that.\\n\\n\\n> But really, for the infinite loop to happen, building a relation descriptor\\n> has to invalidate a cache. And I haven't found a way to do that without the\\n> CLOBBER_CACHE_ALWAYS thing.\\n\\nPhew.\\n\\n\\n> Also, all the November minor releases include this commit, and there were no\\n> reports about this (pretty obvious) issue. Buildfarm did not complain either\\n> (but an animal may be stuck for months and we would not know about it).\\n\\nAh, somehow I thought that wasn't yet in the last set of releases. Phew #2.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Feb 2022 17:53:59 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\\n> On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\\n> > On 10/24/21 03:40, Noah Misch wrote:\\n> > > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n> > > \\n> > > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\n> > > no later than each backend's next transaction start. That failed to\\n> > > hold when a backend absorbed a relevant invalidation in the middle of\\n> > > running RelationBuildDesc() on the CIC index. Queries that use the\\n> > > resulting index can silently fail to find rows. Fix this for future\\n> > > index builds by making RelationBuildDesc() loop until it finishes\\n> > > without accepting a relevant invalidation. It may be necessary to\\n> > > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\n> > > Back-patch to 9.6 (all supported versions).\\n> > > \\n> > > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\n> > > Freund.\\n> > > \\n> > > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n> > > \\n> > \\n> > Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\\n> > this commit, initdb never completes due to infinite retrying over and over\\n> > (on the first RelationBuildDesc call).\\n\\nThanks for the report. I had added the debug_discard arguments of\\nInvalidateSystemCachesExtended() and RelationCacheInvalidate() to make the new\\ncode survive a CREATE TABLE at debug_discard_caches=5. Apparently that's not\\nenough for initdb. I'll queue a task to look at it.\\n\\nIt's a good reminder to set wait_timeout on buildfarm animals. (I should take\\nthat advice, too.)\\n\\n> Ugh. Do we need to do something about WRT the next set of minor releases?\\n\\nNo, given that this code already debuted in the November releases.\\n\\n\\n\",\n \"msg_date\": \"Tue, 8 Feb 2022 18:04:03 -0800\",\n \"msg_from\": \"Noah Misch <noah@leadboat.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 08, 2022 at 05:43:34PM -0800, Andres Freund wrote:\\n> It's stamped, not tagged, so we could send out new tarballs. Or we could skip\\n> a release number. IIRC we had to do something along those lines before.\\n\\nIt does not matter now, but the release is stamped and tagged.\\n\\n> What do you mean with detect here?\\n\\nWell, we would not be able to see that something is stuck by default,\\nbut Noah has just answered to my question by mentioning wait_timeout\\nin the buildfarm configuration.\\n--\\nMichael\",\n \"msg_date\": \"Wed, 9 Feb 2022 11:24:21 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 08, 2022 at 06:04:03PM -0800, Noah Misch wrote:\\n> On Tue, Feb 08, 2022 at 04:43:47PM -0800, Andres Freund wrote:\\n> > On 2022-02-08 22:13:01 +0100, Tomas Vondra wrote:\\n> > > On 10/24/21 03:40, Noah Misch wrote:\\n> > > > Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\\n> > > > \\n> > > > CIC and REINDEX CONCURRENTLY assume backends see their catalog changes\\n> > > > no later than each backend's next transaction start. That failed to\\n> > > > hold when a backend absorbed a relevant invalidation in the middle of\\n> > > > running RelationBuildDesc() on the CIC index. Queries that use the\\n> > > > resulting index can silently fail to find rows. Fix this for future\\n> > > > index builds by making RelationBuildDesc() loop until it finishes\\n> > > > without accepting a relevant invalidation. It may be necessary to\\n> > > > reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.\\n> > > > Back-patch to 9.6 (all supported versions).\\n> > > > \\n> > > > Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres\\n> > > > Freund.\\n> > > > \\n> > > > Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com\\n> > > > \\n> > > \\n> > > Unfortunately, this seems to have broken CLOBBER_CACHE_ALWAYS builds. Since\\n> > > this commit, initdb never completes due to infinite retrying over and over\\n> > > (on the first RelationBuildDesc call).\\n> \\n> Thanks for the report. I had added the debug_discard arguments of\\n> InvalidateSystemCachesExtended() and RelationCacheInvalidate() to make the new\\n> code survive a CREATE TABLE at debug_discard_caches=5. Apparently that's not\\n> enough for initdb. I'll queue a task to look at it.\\n\\nThe explanation was more boring than that. v13 and earlier have an additional\\nInvalidateSystemCaches() call site, which I neglected to update. Here's the\\nfix I intend to push.\",\n \"msg_date\": \"Tue, 8 Feb 2022 21:41:41 -0800\",\n \"msg_from\": \"Noah Misch <noah@leadboat.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"Michael Paquier <michael@paquier.xyz> writes:\\n> On Tue, Feb 08, 2022 at 05:43:34PM -0800, Andres Freund wrote:\\n>> It's stamped, not tagged, so we could send out new tarballs. Or we could skip\\n>> a release number. IIRC we had to do something along those lines before.\\n\\n> It does not matter now, but the release is stamped and tagged.\\n\\nYeah, I see no need to do anything about this on an emergency\\nbasis.\\n\\n>> What do you mean with detect here?\\n\\n> Well, we would not be able to see that something is stuck by default,\\n> but Noah has just answered to my question by mentioning wait_timeout\\n> in the buildfarm configuration.\\n\\nThe buildfarm's wait_timeout option isn't that helpful here, because\\nwhen it triggers, the client just goes belly-up *with no report*.\\nSo even if the CCA animals had it on, you'd not notice unless you\\nstarted to wonder why they'd not reported lately.\\n\\nI think that's a bug that ought to be fixed. I do agree that\\nwait_timeout ought to be finite by default, too.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 09 Feb 2022 00:44:42 -0500\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n },\n {\n \"msg_contents\": \"On 2/9/22 06:41, Noah Misch wrote:\\n>\\n> The explanation was more boring than that. v13 and earlier have an additional\\n> InvalidateSystemCaches() call site, which I neglected to update. Here's the\\n> fix I intend to push.\\n\\nI tried this patch on 10 and 13, and it seems to fix the issue. So +1.\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Wed, 9 Feb 2022 16:27:39 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX\\n CONCURR\"\n }\n]","isConversational":false}}},{"rowIdx":52990,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi everyone. I want to do some feature request regarding indexes, as far as\nI know this kind of functionality doesn't exists in Postgres. Here is my\nproblem :\nI need to create following indexes:\n Create index job_nlp_year_scan on ingest_scans_stageing\n(`job`,`nlp`,`year`,`scan_id`);\n Create index job_nlp_year_issue_flag on ingest_scans_stageing\n(`job`,`nlp`,`year`,`issue_flag`);\n Create index job_nlp_year_sequence on ingest_scans_stageing\n(`job`,`nlp`,`year`,`sequence`);\nAs you can see the first 3 columns are the same (job, nlp, year). so if I\ncreate 3 different indexes db should manage same job_nlp_year structure 3\ntimes.\nThe Data Structure that I think which can be efficient in this kind of\nscenarios is to have 'Adaptive Index' which will be something like\nCreate index job_nlp_year on ingest_scans_stageing\n(`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\nAnd depend on query it will use or job_nlp_year_scan or\njob_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and one\nof ( `issue_flag` , `scan_id` , `sequence` )\nFor more description please feel free to refer me\n\nHi everyone. I want to do some feature request regarding indexes, as far asI know this kind of functionality doesn't exists in Postgres. Here is myproblem :I need to create following indexes: Create index job_nlp_year_scan on ingest_scans_stageing(`job`,`nlp`,`year`,`scan_id`); Create index job_nlp_year_issue_flag on ingest_scans_stageing(`job`,`nlp`,`year`,`issue_flag`); Create index job_nlp_year_sequence on ingest_scans_stageing(`job`,`nlp`,`year`,`sequence`);As you can see the first 3 columns are the same (job, nlp, year). so if Icreate 3 different indexes db should manage same job_nlp_year structure 3times.The Data Structure that I think which can be efficient in this kind ofscenarios is to have 'Adaptive Index' which will be something likeCreate index job_nlp_year on ingest_scans_stageing(`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));And depend on query it will use or job_nlp_year_scan orjob_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and oneof ( `issue_flag` , `scan_id` , `sequence` )For more description please feel free to refer me","msg_date":"Mon, 25 Oct 2021 18:07:18 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Feature request for adoptive indexes"},{"msg_contents":"Hi,\n\nOn 10/25/21 16:07, Hayk Manukyan wrote:\n> Hi everyone. I want to do some feature request regarding indexes, as far as\n> I know this kind of functionality doesn't exists in Postgres. Here is my\n> problem :\n> I need to create following indexes:\n> Create index job_nlp_year_scan on ingest_scans_stageing\n> (`job`,`nlp`,`year`,`scan_id`);\n> Create index job_nlp_year_issue_flag on ingest_scans_stageing\n> (`job`,`nlp`,`year`,`issue_flag`);\n> Create index job_nlp_year_sequence on ingest_scans_stageing\n> (`job`,`nlp`,`year`,`sequence`);\n> As you can see the first 3 columns are the same (job, nlp, year). so if I\n> create 3 different indexes db should manage same job_nlp_year structure 3\n> times.\n> The Data Structure that I think which can be efficient in this kind of\n> scenarios is to have 'Adaptive Index' which will be something like\n> Create index job_nlp_year on ingest_scans_stageing\n> (`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\n> And depend on query it will use or job_nlp_year_scan or\n> job_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and one\n> of ( `issue_flag` , `scan_id` , `sequence` )\n> For more description please feel free to refer me\n\nIt's not very clear what exactly would the \"adaptive index\" do, except \nthat it'd have all three columns. Clearly, the three columns can't be \nconsidered for ordering etc. but need to be in the index somehow. So why \nwouldn't it be enough to either to create an index with all six columns?\n\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag, \nsequence);\n\nor possibly with the columns just \"included\" in the index:\n\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year) INCLUDE (scan_id, \nissue_flag, sequence);\n\nIf this does not work, you either need to explain more clearly what \nexactly the adaptive indexes does, or show queries that can't benefit \nfrom these existing features.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Mon, 25 Oct 2021 17:33:36 +0200","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"ok. here is the deal if I have the following index with 6 column\n\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\nsequence);\n\nI need to specify all 6 columns in where clause in order to fully use this\nindex.\nIt will not be efficient in cases when I have 4 condition in where clause\nalso I should follow the order of columns.\nIn case of INCLUDE the 3 columns just will be in index but will not be\nstructured as index so it will have affect only if In select I will have\nthat 6 columns nothing more.\n\nIn my case I have table with ~15 columns\nIn my application I have to do a lot of queries with following where\nclauses\n\n1. where job = <something> and nlp = <something> and year = <something>\nand SCAN_ID = <something>\n2. where job = <something> and nlp = <something> and year = <something>\nand ISSUE_FLAG = <something>\n3. where job = <something> and nlp = <something> and year = <something>\nand SEQUENCE = <something>\n\nI don't want to index just on job, nlp, year because for each job, nlp,\nyear I have approximately 5000-7000 rows ,\noverall table have ~50m rows so it is partitioned by job as well. So if I\nbuild 3 separate indexes it will be huge resource.\nSo I am thinking of having one index which will be job, nlp, year and the\n4-th layer will be other columns not just included but also in B-tree\nstructure.\nTo visualize it will be something like this:\n[image: image.png]\nThe red part is ordinary index with nested b-trees ant the yellow part is\nadaptive part so depends on\nwhere clause optimizer can decide which direction (leaf, b-tree whatever)\nto chose.\nIn this case I will have one index and will manage red part only once for\nall three cases.\nThose it make sense ?\nIf you need more discussion we can have short call I will try to explain\nyou in more detailed way.\n\nbest regards\n\nпн, 25 окт. 2021 г. в 19:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\n\n> Hi,\n>\n> On 10/25/21 16:07, Hayk Manukyan wrote:\n> > Hi everyone. I want to do some feature request regarding indexes, as far\n> as\n> > I know this kind of functionality doesn't exists in Postgres. Here is my\n> > problem :\n> > I need to create following indexes:\n> > Create index job_nlp_year_scan on ingest_scans_stageing\n> > (`job`,`nlp`,`year`,`scan_id`);\n> > Create index job_nlp_year_issue_flag on ingest_scans_stageing\n> > (`job`,`nlp`,`year`,`issue_flag`);\n> > Create index job_nlp_year_sequence on ingest_scans_stageing\n> > (`job`,`nlp`,`year`,`sequence`);\n> > As you can see the first 3 columns are the same (job, nlp, year). so if I\n> > create 3 different indexes db should manage same job_nlp_year structure 3\n> > times.\n> > The Data Structure that I think which can be efficient in this kind of\n> > scenarios is to have 'Adaptive Index' which will be something like\n> > Create index job_nlp_year on ingest_scans_stageing\n> > (`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\n> > And depend on query it will use or job_nlp_year_scan or\n> > job_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and\n> one\n> > of ( `issue_flag` , `scan_id` , `sequence` )\n> > For more description please feel free to refer me\n>\n> It's not very clear what exactly would the \"adaptive index\" do, except\n> that it'd have all three columns. Clearly, the three columns can't be\n> considered for ordering etc. but need to be in the index somehow. So why\n> wouldn't it be enough to either to create an index with all six columns?\n>\n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\n> sequence);\n>\n> or possibly with the columns just \"included\" in the index:\n>\n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year) INCLUDE (scan_id,\n> issue_flag, sequence);\n>\n> If this does not work, you either need to explain more clearly what\n> exactly the adaptive indexes does, or show queries that can't benefit\n> from these existing features.\n>\n>\n> regards\n>\n> --\n> Tomas Vondra\n> EnterpriseDB: http://www.enterprisedb.com\n> The Enterprise PostgreSQL Company\n>","msg_date":"Tue, 26 Oct 2021 10:49:31 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\nOn 10/26/21 8:49 AM, Hayk Manukyan wrote:\n> ok. here is the deal if I have the following index with 6 column\n> \n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\n> sequence);\n> \n> I need to specify all 6 columns in where clause in order to fully use\n> this index.\n\nWhat do you mean by \"fully use this index\"? Yes, the query may use just\nsome of the columns and there will be a bit of overhead, but I doubt\nit'll be measurable.\n\n> It will not be efficient in cases when I have 4 condition in where\n> clause also I should follow the order of columns.\n\nSo, do some experiments and show us what the difference is. Create an\nindex on the 4 and 6 columns, and measure timings for a query with just\nthe 4 columns.\n\n> In case of INCLUDE the 3 columns just will be in index but will not be\n> structured as index so it will have affect only if In select I will have\n> that 6 columns nothing more.\n> \n> In my case I have table with ~15 columns\n> In my application I have to do a lot of queries with following where\n> clauses \n> \n> 1. where job = <something> and nlp = <something> and year = <something>\n> and SCAN_ID = <something>\n> 2. where job = <something> and nlp = <something> and year = <something>\n> and ISSUE_FLAG = <something>\n> 3. where job = <something> and nlp = <something> and year = <something>\n> and SEQUENCE = <something>\n> \n> I don't want to index just on job, nlp, year because for each job,\n> nlp, year I have approximately 5000-7000 rows ,\n> overall table have ~50m rows so it is partitioned by job as well. So if\n> I build 3 separate indexes it will be huge resource.\n> So I am thinking of having one index which will be job, nlp, year and\n> the 4-th layer will be other columns not just included but also in\n> B-tree structure. \n> To visualize it will be something like this:\n> image.png\n> The red part is ordinary index with nested b-trees ant the yellow part\n> is adaptive part so depends on\n> where clause optimizer can decide which direction (leaf, b-tree\n> whatever) to chose.\n> In this case I will have one index and will manage red part only once\n> for all three cases.\n> Those it make sense ? \n\nIf I get what you propose, you want to have a \"top\" tree for (job, nlp,\nyear), which \"splits\" the data set into subsets of ~5000-7000 rows. And\nthen for each subset you want a separate \"small\" trees on each of the\nother columns, so in this case three trees.\n\nWell, the problem with this is pretty obvious - each of the small trees\nrequires separate copies of the leaf pages. And remember, in a btree the\ninternal pages are usually less than 1% of the index, so this pretty\nmuch triples the size of the index. And if you insert a row into the\nindex, it has to insert the item pointer into each of the small trees,\nlikely requiring a separate I/O for each.\n\nSo I'd bet this is not any different from just having three separate\nindexes - it doesn't save space, doesn't save I/O, nothing.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Tue, 26 Oct 2021 17:08:59 +0200","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"I've already answered OP but it seems in the wrong thread, so I copy it\nhere:\n\nI think now in many cases you can effectively use covering index to have\nfast index-only scans without index duplication. It will help if you don't\nhave great selectivity on the last column (most probably you don't). E.g.:\n\nCREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`,\n`issue_flag`, `sequence`)\n\nBut I consider the feature can be useful when there is a very little\nselectivity in the first index columns. I.e. if (job`,`nlp`,`year') has\nmany repeats and the most selection is done in the last column. I am not\nsure how often this can arise but in general, I see it as a useful b-tree\ngeneralization.\n\nI'm not sure how it should be done. In my view, we need to add an ordered\nposting tree as a leaf element if b-tree and now we have index storage only\nfor tuples. The change of on-disk format was previously not easy in nbtree\nand if we consider the change, we need an extra bit to mark posting trees\namong index tuples. Maybe it could be done in a way similar to deduplicated\ntuples if some bits in the tuple header are still could be freed.\n\nThoughts?\n\nIf I get what you propose, you want to have a \"top\" tree for (job, nlp,\n> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n> then for each subset you want a separate \"small\" trees on each of the\n> other columns, so in this case three trees.\n>\n> Well, the problem with this is pretty obvious - each of the small trees\n> requires separate copies of the leaf pages. And remember, in a btree the\n> internal pages are usually less than 1% of the index, so this pretty\n> much triples the size of the index. And if you insert a row into the\n> index, it has to insert the item pointer into each of the small trees,\n> likely requiring a separate I/O for each.\n>\n> So I'd bet this is not any different from just having three separate\n> indexes - it doesn't save space, doesn't save I/O, nothing.\n>\n\nTomas, I really think we should not try realizing this feature using\nexisting index pages that contain only tuples. You are right, it will cause\nlarge overhead. If instead we decide and succeed in creating \"posting\ntrees\" as a new on-disk page entry type we can have an index with space\ncomparable to the abovementioned covering index but with sorting of values\nin these trees (i.e. all values are sorted, and \"key\" ones).\n\n-- \nBest regards,\nPavel Borisov\n\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\n\nI've already answered OP but it seems in the wrong thread, so I copy it here:I think now in many cases you can effectively use covering index to have fast index-only scans without index duplication. It will help if you don't have great selectivity on the last column (most probably you don't). E.g.:CREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`, `issue_flag`, `sequence`)But I consider the feature can be useful when there is a very little selectivity in the first index columns. I.e. if (job`,`nlp`,`year') has many repeats and the most selection is done in the last column. I am not sure how often this can arise but in general, I see it as a useful b-tree generalization.I'm not sure how it should be done. In my view, we need to add an ordered posting tree as a leaf element if b-tree and now we have index storage only for tuples. The change of on-disk format was previously not easy in nbtree and if we consider the change, we need an extra bit to mark posting trees among index tuples. Maybe it could be done in a way similar to deduplicated tuples if some bits in the tuple header are still could be freed.Thoughts? If I get what you propose, you want to have a \"top\" tree for (job, nlp,\nyear), which \"splits\" the data set into subsets of ~5000-7000 rows. And\nthen for each subset you want a separate \"small\" trees on each of the\nother columns, so in this case three trees.\n\nWell, the problem with this is pretty obvious - each of the small trees\nrequires separate copies of the leaf pages. And remember, in a btree the\ninternal pages are usually less than 1% of the index, so this pretty\nmuch triples the size of the index. And if you insert a row into the\nindex, it has to insert the item pointer into each of the small trees,\nlikely requiring a separate I/O for each.\n\nSo I'd bet this is not any different from just having three separate\nindexes - it doesn't save space, doesn't save I/O, nothing. Tomas, I really think we should not try realizing this feature using existing index pages that contain only tuples. You are right, it will cause large overhead. If instead we decide and succeed in creating \"posting trees\" as a new on-disk page entry type we can have an index with space comparable to the abovementioned covering index but with sorting of values in these trees (i.e. all values are sorted, and \"key\" ones).-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com","msg_date":"Tue, 26 Oct 2021 23:39:20 +0400","msg_from":"Pavel Borisov <pashkin.elfe@gmail.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\nOn 10/26/21 21:39, Pavel Borisov wrote:\n> I've already answered OP but it seems in the wrong thread, so I copy it \n> here:\n> \n> I think now in many cases you can effectively use covering index to have \n> fast index-only scans without index duplication. It will help if you \n> don't have great selectivity on the last column (most probably you \n> don't). E.g.:\n> \n> CREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`, \n> `issue_flag`, `sequence`)\n> \n> But I consider the feature can be useful when there is a very little \n> selectivity in the first index columns. I.e. if (job`,`nlp`,`year') has \n> many repeats and the most selection is done in the last column. I am not \n> sure how often this can arise but in general, I see it as a useful \n> b-tree generalization.\n> \n> I'm not sure how it should be done. In my view, we need to add an \n> ordered posting tree as a leaf element if b-tree and now we have index \n> storage only for tuples. The change of on-disk format was previously not \n> easy in nbtree and if we consider the change, we need an extra bit to \n> mark posting trees among index tuples. Maybe it could be done in a way \n> similar to deduplicated tuples if some bits in the tuple header are \n> still could be freed.\n> \n> Thoughts?\n> \n> If I get what you propose, you want to have a \"top\" tree for (job, nlp,\n> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n> then for each subset you want a separate \"small\" trees on each of the\n> other columns, so in this case three trees.\n> \n> Well, the problem with this is pretty obvious - each of the small trees\n> requires separate copies of the leaf pages. And remember, in a btree the\n> internal pages are usually less than 1% of the index, so this pretty\n> much triples the size of the index. And if you insert a row into the\n> index, it has to insert the item pointer into each of the small trees,\n> likely requiring a separate I/O for each.\n> \n> So I'd bet this is not any different from just having three separate\n> indexes - it doesn't save space, doesn't save I/O, nothing.\n> \n> Tomas, I really think we should not try realizing this feature using \n> existing index pages that contain only tuples. You are right, it will \n> cause large overhead. If instead we decide and succeed in creating \n> \"posting trees\" as a new on-disk page entry type we can have an index \n> with space comparable to the abovementioned covering index but with \n> sorting of values in these trees (i.e. all values are sorted, and \"key\" \n> ones).\n> \n\nWell, there was no explanation about how it could/should be implemented, \nand maybe there is some elaborate way to handle the \"posting trees\" that \nI can't quite think of (at least not in the btree context).\n\nI'm still rather skeptical about it - for such feature to be useful the \nprefix columns must not be very selective, i.e. the posting trees are \nexpected to be fairly large (e.g. 5-7k rows). It pretty much has to to \nrequire multiple (many) index pages, in order for the \"larger\" btree \nindex to be slower. And at that point I'd expect the extra overhead to \nbe worse than simply defining multiple simple indexes.\n\nA simple experiment would be to measure timing for queries with a \ncondition on \"sequence\" using two indexes:\n\n1) (job, nlp, year, sequence)\n2) (job, nlp, year, scan_id, issue_flag, sequence)\n\nThe (1) index is \"optimal\" i.e. there's unlikely to be a better index \nfor this query, at least no tree-like. (2) is something like the \"worst\" \ncase index that we can use for this query.\n\nFor the new feature to be useful, two things would need to be true:\n\n* query with (2) is much slower than (1)\n* the new index would need to be close to (1)\n\nObviously, if the new index is slower than (2), it's mostly useless \nright off the bat. And it probably can't be faster than (1) in practice, \nas it still is basically a btree index (at least the top half).\n\nSo I'd expect the performance to be somewhere between (1) and (2), but \nif (2) is very close to (1) - which I'd bet it is - then the potential \nbenefit is also pretty small.\n\nPerhaps I'm entirely wrong and there's a new type of index, better \nsuited for cases similar to this. The \"posting tree\" reference actually \nmade me thinking that maybe btree_gin might be applicable here?\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Tue, 26 Oct 2021 22:43:22 +0200","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\n> On Oct 26, 2021, at 1:43 PM, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote:\n> \n> I'm still rather skeptical about it - for such feature to be useful the prefix columns must not be very selective, i.e. the posting trees are expected to be fairly large (e.g. 5-7k rows). It pretty much has to to require multiple (many) index pages, in order for the \"larger\" btree index to be slower. And at that point I'd expect the extra overhead to be worse than simply defining multiple simple indexes.\n\nFor three separate indexes, an update or delete of a single row in the indexed table would surely require changing at least three pages in the indexes. For some as-yet-ill-defined combined index type, perhaps the three entries in the index would fall on the same index page often enough to reduce the I/O cost of the action? This is all hard to contemplate without a more precise description of the index algorithm.\n\nPerhaps the OP might want to cite a paper describing a particular index algorithm for us to review?\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 26 Oct 2021 15:08:37 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"Mark Dilger <mark.dilger@enterprisedb.com> writes:\n> For three separate indexes, an update or delete of a single row in the indexed table would surely require changing at least three pages in the indexes. For some as-yet-ill-defined combined index type, perhaps the three entries in the index would fall on the same index page often enough to reduce the I/O cost of the action?\n\nOf course, we have that today from the solution of one index with the\nextra columns \"included\". I think the OP has completely failed to make\nany case why that's not a good enough approach.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 18:45:36 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"On Tue, Oct 26, 2021 at 3:45 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> Of course, we have that today from the solution of one index with the\n> extra columns \"included\". I think the OP has completely failed to make\n> any case why that's not a good enough approach.\n\nI think that the design that the OP is talking about (adaptive\nindexes, AKA merged indexes with master detail clustering) have been\nthe subject of certain research papers. As far as I know nothing like\nthat has ever been implemented in a real DB system.\n\nIt seems like a daunting project, primarily because of the concurrency\ncontrol considerations. It's no coincidence that GIN indexes (which\nhave some of the same issues) only support lossy index scans. Lossy\nscans don't seem to be compatible with adaptive indexes, since the\nwhole point is to have multiple distinct \"logical indexes\" with a\ncommon prefix, but only one physical index, with clustering. I think\nyou'd need something like ARIES KVL for concurrency control, just for\nstarters. Even that is something that won't work with anything like\ncurrent Postgres.\n\nIt's roughly the same story that we see with generalizing TIDs at the\ntableam level. People tend to imagine that it's basically just a\nmatter of coming up with the right index AM data structure, but that's\nactually just the easy part.\n\n-- \nPeter Geoghegan\n\n\n","msg_date":"Tue, 26 Oct 2021 16:30:52 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":">\n> It's no coincidence that GIN indexes (which\n> have some of the same issues) only support lossy index scans.\n>\nAFAIK Gin is lossy for phrase queries as we don't store word position in\nthe posting list. For purely logical queries, where position doesn't\nmatter, it's not lossy.\n\nOne more consideration against the proposal is that if we want to select\nwith more than one \"suffix\" columns in the WHERE clause, effectively we\nwill have a join of two separate index scans. And as we consider suffix\ncolumns to be highly selective, and prefix columns are weakly selective,\nthen it could be very slow.\n\nJust some ideas on the topic which may not be connected to OP proposal (Not\nsure whether should we implement them as a part of nbtree) :\n\n1. If prefix columns have low selectivity it may be good if we have some\nattribute-level deduplication only for prefix columns.\n2. If we have several suffix columns, it might be a good idea is to treat\nthem as an n-dimensional space and define some R-tree or Quad-tree on top\nof them (using GiST, SpGIST).\n\n-- \nBest regards,\nPavel Borisov\n\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\n\nIt's no coincidence that GIN indexes (which\nhave some of the same issues) only support lossy index scans. AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.One more consideration against the proposal is that if we want to select with more than one \"suffix\" columns in the WHERE clause, effectively we will have a join of two separate index scans. And as we consider suffix columns to be highly selective, and prefix columns are weakly selective, then it could be very slow. Just some ideas on the topic which may not be connected to OP proposal (Not sure whether should we implement them as a part of nbtree) :1. If prefix columns have low selectivity it may be good if we have some attribute-level deduplication only for prefix columns.2. If we have several suffix columns, it might be a good idea is to treat them as an n-dimensional space and define some R-tree or Quad-tree on top of them (using GiST, SpGIST).-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com","msg_date":"Wed, 27 Oct 2021 12:02:23 +0400","msg_from":"Pavel Borisov <pashkin.elfe@gmail.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com> wrote:\n> AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.\n\nGIN is always lossy, in the sense that it provides only a\ngingetbitmap() routine -- there is no gingettuple() routine. I believe\nthat this is fundamental to the overall design of GIN. It would be\nvery difficult to add useful gingettuple() functionality now, since\nGIN already relies on lossiness to avoid race conditions.\n\nHere's an example of the problems that \"adding gingettuple()\" would\nrun into: Today, an index's pending list entries can be merged\nconcurrently with the entry tree, without worrying about returning the\nsame tuples twice. This is only safe/correct because GIN only supports\nbitmap index scans. Without that, you need some other mechanism to\nmake it safe -- ISTM you must \"logically lock\" the index structure,\nusing ARIES/KVL style key value locks, or something along those lines.\n\n-- \nPeter Geoghegan\n\n\n","msg_date":"Wed, 27 Oct 2021 09:10:32 -0700","msg_from":"Peter Geoghegan <pg@bowt.ie>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"Hi all\nFirst of all thank you all for fast and rich responses, that is really nice.\nI don't have that deep knowledge of how postgres works under the hood so I\nwill try to explain more user side.\nI want to refer for some points mentioned above.\n - First INCLUDE statement mostly eliminates the necessity to refer to a\nclustered index or table to get columns that do not exist in the index. So\nfiltering upon columns in INCLUDE statement will not be performant. It can\ngive some very little performance if we include additional columns but it\nis not in level to compare with indexed one. I believe this not for this\ncase\n- Tomas Vondra's Assumption that adaptive should be something between this\ntwo\n1) (job, nlp, year, sequence)\n2) (job, nlp, year, scan_id, issue_flag, sequence)\nis completely valid. I have made fairly small demo with this index\ncomparison and as I can see the difference is noticeable. Here is git repo\nand results\n<https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/results.md>\n,\nI had no much time to do significant one sorry for that ))\n - regarding data structure side of things by Pavel Borisov.\nI also think that different data structure will be needed. Not sure exactly\nat this point which kind of data structure but I will try to explain it\nhere.\n<https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/data_structure.md>\n\nbest regards\n\n\nср, 27 окт. 2021 г. в 20:10, Peter Geoghegan <pg@bowt.ie>:\n\n> On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com>\n> wrote:\n> > AFAIK Gin is lossy for phrase queries as we don't store word position in\n> the posting list. For purely logical queries, where position doesn't\n> matter, it's not lossy.\n>\n> GIN is always lossy, in the sense that it provides only a\n> gingetbitmap() routine -- there is no gingettuple() routine. I believe\n> that this is fundamental to the overall design of GIN. It would be\n> very difficult to add useful gingettuple() functionality now, since\n> GIN already relies on lossiness to avoid race conditions.\n>\n> Here's an example of the problems that \"adding gingettuple()\" would\n> run into: Today, an index's pending list entries can be merged\n> concurrently with the entry tree, without worrying about returning the\n> same tuples twice. This is only safe/correct because GIN only supports\n> bitmap index scans. Without that, you need some other mechanism to\n> make it safe -- ISTM you must \"logically lock\" the index structure,\n> using ARIES/KVL style key value locks, or something along those lines.\n>\n> --\n> Peter Geoghegan\n>\n\nHi allFirst of all thank you all for fast and rich responses, that is really nice.I don't have that deep knowledge of how postgres works under the hood so I will try to explain more user side.I want to refer for some points mentioned above. - First INCLUDE statement mostly eliminates the necessity to refer to a clustered index or table to get columns that do not exist in the index. So filtering upon columns in INCLUDE statement will not be performant. It can give some very little performance if we include additional columns but it is not in level to compare with indexed one. I believe this not for this case- Tomas Vondra's Assumption that adaptive should be something between this two 1) (job, nlp, year, sequence)2) (job, nlp, year, scan_id, issue_flag, sequence) is completely valid. I have made fairly small demo with this index comparison and as I can see the difference is noticeable. Here is git repo and results , I had no much time to do significant one sorry for that )) - regarding data structure side of things by Pavel Borisov. I also think that different data structure will be needed. Not sure exactly at this point which kind of data structure but I will try to explain it here.best regards ср, 27 окт. 2021 г. в 20:10, Peter Geoghegan <pg@bowt.ie>:On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com> wrote:\n> AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.\n\nGIN is always lossy, in the sense that it provides only a\ngingetbitmap() routine -- there is no gingettuple() routine. I believe\nthat this is fundamental to the overall design of GIN. It would be\nvery difficult to add useful gingettuple() functionality now, since\nGIN already relies on lossiness to avoid race conditions.\n\nHere's an example of the problems that \"adding gingettuple()\" would\nrun into: Today, an index's pending list entries can be merged\nconcurrently with the entry tree, without worrying about returning the\nsame tuples twice. This is only safe/correct because GIN only supports\nbitmap index scans. Without that, you need some other mechanism to\nmake it safe -- ISTM you must \"logically lock\" the index structure,\nusing ARIES/KVL style key value locks, or something along those lines.\n\n-- \nPeter Geoghegan","msg_date":"Fri, 29 Oct 2021 17:32:37 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"On 10/29/21 15:32, Hayk Manukyan wrote:\n> Hi all\n> First of all thank you all for fast and rich responses, that is really nice.\n> I don't have that deep knowledge of how postgres works under the hood \n> so I will try to explain more user side.\n> I want to refer for some points mentioned above.\n> - First INCLUDE statement mostly eliminates the necessity to refer to \n> a clustered index or table to get columns that do not exist in the \n> index. So filtering upon columns in INCLUDE statement will not be \n> performant. It can give some very little performance if we include \n> additional columns but it is not in level to compare with indexed one. I \n> believe this not for this case\n> - Tomas Vondra's Assumption that adaptive should be something between \n> this two\n> 1) (job, nlp, year, sequence)\n> 2) (job, nlp, year, scan_id, issue_flag, sequence)\n> is completely valid. I have made fairly small demo with this index \n> comparison and as I can see the difference is noticeable. Here is git \n> repo and results \n> <https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/results.md> , \n> I had no much time to do significant one sorry for that ))\n\nI find those results entirely unconvincing, or maybe even suspicious.\n\nI used the script to create the objects, and the index sizes are:\n\n Name | Size\n ------------------------------------------+---------\n job_nlp_year_scan_id_issue_flag_sequence | 1985 MB\n job_nlp_year_sequence | 1985 MB\n\nSo there's no actual difference, most likely due to alignment making up \nfor the two smalling columns.\n\nAnd if I randomize the queries instead of running them with the same \nparameters over and over (see the attached scripts), then an average of \n10 runs, each 60s long, the results are (after a proper warmup)\n\n pgbench -n -f q4.sql -T 60\n\n 4 columns: 106 ms\n 6 columns: 109 ms\n\nSo there's like 3% difference between the two cases, and even that might \nbe just noise. This is consistent with the two indexes being about the \nsame size.\n\nThis is on machine with i5-2500k CPU and 8GB of RAM, which is just \nenough to keep everything in RAM. It seems somewhat strange that your \nmachine does this in 10ms, i.e. 10x faster. Seems strange.\n\n\nI'm not sure what is the point of the second query, considering it's not \neven using an index but parallel seqscan.\n\n\nAnyway, this still fails to demonstrate any material difference between \nthe two indexes, and consequently any potential benefit of the proposed \nnew index type.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Sat, 30 Oct 2021 01:44:08 +0200","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":">\n> 4 columns: 106 ms\n> 6 columns: 109 ms\n>\n> So there's like 3% difference between the two cases, and even that might\n> be just noise. This is consistent with the two indexes being about the\n> same size.\n>\nI also don't think we can get great speedup in the mentioned case, so it is\nnot urgently needed of course. My point is that it is just nice to have a\nmulticolumn index constructed on stacked trees constructed on separate\ncolumns, not on the index tuples as a whole thing. At least there is a\nbenefit of sparing shared memory if we don't need to cache index tuples of\nseveral similar indexes, instead caching one \"compound index\". So if\nsomeone wants to propose this thing I'd support it provided problems with\nconcurrency, which were mentioned by Peter are solved.\n\nThese problems could be appear easy though, as we have index tuples\nconstructed in a similar way as heap tuples. Maybe it could be easier if we\nhad another heap am, which stored separate attributes (if so it could be\nuseful as a better JSON storage method than we have today).\n\n--\nBest regards,\nPavel Borisov\n\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\n\n 4 columns: 106 ms\n 6 columns: 109 ms\n\nSo there's like 3% difference between the two cases, and even that might \nbe just noise. This is consistent with the two indexes being about the \nsame size.I also don't think we can get great speedup in the mentioned case, so it is not urgently needed of course. My point is that it is just nice to have a multicolumn index constructed on stacked trees constructed on separate columns, not on the index tuples as a whole thing. At least there is a benefit of sparing shared memory if we don't need to cache index tuples of several similar indexes, instead caching one \"compound index\". So if someone wants to propose this thing I'd support it provided problems with concurrency, which were mentioned by Peter are solved. These problems could be appear easy though, as we have index tuples constructed in a similar way as heap tuples. Maybe it could be easier if we had another heap am, which stored separate attributes (if so it could be useful as a better JSON storage method than we have today).--Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com","msg_date":"Sun, 31 Oct 2021 19:48:34 +0400","msg_from":"Pavel Borisov <pashkin.elfe@gmail.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\nOn 10/31/21 16:48, Pavel Borisov wrote:\n> 4 columns: 106 ms\n> 6 columns: 109 ms\n> \n> So there's like 3% difference between the two cases, and even that\n> might\n> be just noise. This is consistent with the two indexes being about the\n> same size.\n> \n> I also don't think we can get great speedup in the mentioned case, so it \n> is not urgently needed of course. My point is that it is just nice to \n> have a multicolumn index constructed on stacked trees constructed on \n> separate columns, not on the index tuples as a whole thing.\n\nWell, I'd say \"nice to have\" features are pointless unless they actually \ngive tangible benefits (like speedup) to users. I'd bet no one is going \nto implement and maintain something unless it has such benefit, because \nthey have to weight it against other beneficial features.\n\nMaybe there are use cases where this would be beneficial, but so far we \nhaven't seen one. Usually it's the OP who presents such a case, and a \nplausible way to improve it - but it seems this thread presents a \nsolution and now we're looking for an issue it might solve.\n\n> At least there is a benefit of sparing shared memory if we don't need\n> to cache index tuples of several similar indexes, instead caching one\n> \"compound index\". So if someone wants to propose this thing I'd\n> support it provided problems with concurrency, which were mentioned\n> by Peter are solved.\n> \n\nThe problem with this it assumes the new index would use (significantly) \nless space than three separate indexes. I find that rather unlikely, but \nmaybe there is a smart way to achieve that (certainly not in detail).\n\nI don't want to sound overly pessimistic and if you have an idea how to \ndo this, I'd like to hear it. But it seems pretty tricky, particularly \nif we assume the suffix columns are more variable (which limits the \n\"compression\" ratio etc.).\n\n> These problems could be appear easy though, as we have index tuples \n> constructed in a similar way as heap tuples. Maybe it could be easier if \n> we had another heap am, which stored separate attributes (if so it could \n> be useful as a better JSON storage method than we have today).\n> \n\nIMO this just moved the goalposts somewhere outside the solar system.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Sun, 31 Oct 2021 18:33:54 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"I agree with the above mentioned.\nThe only concern I have is that we compare little wrong things.\nFor read we should compare\n (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\nyear, issue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag)\nOR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )\nBecause our proposed index for reading should be closer to a combination of\nthose 3 and we have current solutions like index on all or with Include\nstatement.\nWe should try to find a gap between these three cases.\nFor DML queries\n (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year\nINCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence) AND\n(job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )\nBecause again the proposed index should be just one and cover all 3\nseparate ones.\n\nIf you agree with these cases I will try to find a bigger time frame to\ncompare these two cases deeper.\nThe issue is not high prio but I strongly believe it can help and can be\nnice feature for even more complicated cases.\n\nBest regards.\n\n\n\n\nвс, 31 окт. 2021 г. в 21:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\n\n>\n>\n> On 10/31/21 16:48, Pavel Borisov wrote:\n> > 4 columns: 106 ms\n> > 6 columns: 109 ms\n> >\n> > So there's like 3% difference between the two cases, and even that\n> > might\n> > be just noise. This is consistent with the two indexes being about\n> the\n> > same size.\n> >\n> > I also don't think we can get great speedup in the mentioned case, so it\n> > is not urgently needed of course. My point is that it is just nice to\n> > have a multicolumn index constructed on stacked trees constructed on\n> > separate columns, not on the index tuples as a whole thing.\n>\n> Well, I'd say \"nice to have\" features are pointless unless they actually\n> give tangible benefits (like speedup) to users. I'd bet no one is going\n> to implement and maintain something unless it has such benefit, because\n> they have to weight it against other beneficial features.\n>\n> Maybe there are use cases where this would be beneficial, but so far we\n> haven't seen one. Usually it's the OP who presents such a case, and a\n> plausible way to improve it - but it seems this thread presents a\n> solution and now we're looking for an issue it might solve.\n>\n> > At least there is a benefit of sparing shared memory if we don't need\n> > to cache index tuples of several similar indexes, instead caching one\n> > \"compound index\". So if someone wants to propose this thing I'd\n> > support it provided problems with concurrency, which were mentioned\n> > by Peter are solved.\n> >\n>\n> The problem with this it assumes the new index would use (significantly)\n> less space than three separate indexes. I find that rather unlikely, but\n> maybe there is a smart way to achieve that (certainly not in detail).\n>\n> I don't want to sound overly pessimistic and if you have an idea how to\n> do this, I'd like to hear it. But it seems pretty tricky, particularly\n> if we assume the suffix columns are more variable (which limits the\n> \"compression\" ratio etc.).\n>\n> > These problems could be appear easy though, as we have index tuples\n> > constructed in a similar way as heap tuples. Maybe it could be easier if\n> > we had another heap am, which stored separate attributes (if so it could\n> > be useful as a better JSON storage method than we have today).\n> >\n>\n> IMO this just moved the goalposts somewhere outside the solar system.\n>\n>\n> regards\n>\n> --\n> Tomas Vondra\n> EnterpriseDB: http://www.enterprisedb.com\n> The Enterprise PostgreSQL Company\n>\n\nI agree with the above mentioned. The only concern I have is that we compare little wrong things.For read we should compare (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, \n\nissue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )Because our proposed index for reading should be closer to a combination of those 3 and we have current solutions like index on all or with Include statement. We should try to find a gap between these three cases.For DML queries (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )Because again the proposed index should be just one and cover all 3 separate ones. If you agree with these cases I will try to find a bigger time frame to compare these two cases deeper. The issue is not high prio but I strongly believe it can help and can be nice feature for even more complicated cases.Best regards. вс, 31 окт. 2021 г. в 21:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\n\nOn 10/31/21 16:48, Pavel Borisov wrote:\n> 4 columns: 106 ms\n> 6 columns: 109 ms\n> \n> So there's like 3% difference between the two cases, and even that\n> might\n> be just noise. This is consistent with the two indexes being about the\n> same size.\n> \n> I also don't think we can get great speedup in the mentioned case, so it \n> is not urgently needed of course. My point is that it is just nice to \n> have a multicolumn index constructed on stacked trees constructed on \n> separate columns, not on the index tuples as a whole thing.\n\nWell, I'd say \"nice to have\" features are pointless unless they actually \ngive tangible benefits (like speedup) to users. I'd bet no one is going \nto implement and maintain something unless it has such benefit, because \nthey have to weight it against other beneficial features.\n\nMaybe there are use cases where this would be beneficial, but so far we \nhaven't seen one. Usually it's the OP who presents such a case, and a \nplausible way to improve it - but it seems this thread presents a \nsolution and now we're looking for an issue it might solve.\n\n> At least there is a benefit of sparing shared memory if we don't need\n> to cache index tuples of several similar indexes, instead caching one\n> \"compound index\". So if someone wants to propose this thing I'd\n> support it provided problems with concurrency, which were mentioned\n> by Peter are solved.\n> \n\nThe problem with this it assumes the new index would use (significantly) \nless space than three separate indexes. I find that rather unlikely, but \nmaybe there is a smart way to achieve that (certainly not in detail).\n\nI don't want to sound overly pessimistic and if you have an idea how to \ndo this, I'd like to hear it. But it seems pretty tricky, particularly \nif we assume the suffix columns are more variable (which limits the \n\"compression\" ratio etc.).\n\n> These problems could be appear easy though, as we have index tuples \n> constructed in a similar way as heap tuples. Maybe it could be easier if \n> we had another heap am, which stored separate attributes (if so it could \n> be useful as a better JSON storage method than we have today).\n> \n\nIMO this just moved the goalposts somewhere outside the solar system.\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Mon, 1 Nov 2021 16:24:38 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"On 11/1/21 1:24 PM, Hayk Manukyan wrote:\n> I agree with the above mentioned. \n> The only concern I have is that we compare little wrong things.\n> For read we should compare \n> (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\n> year, issue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag)\n> OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )\n> Because our proposed index for reading should be closer to a combination\n> of those 3 and we have current solutions like index on all or with\n> Include statement. \n\nI don't follow.\n\nThe whole point of the experiment was to show the gap between a \"best\ncase\" and \"worst case\" alternatives, with the assumption the gap would\nbe substantial and the new index type might get close to the best case.\n\nAre you suggesting those are not the actual best/worst cases and we\nshould use some other indexes? If yes, which ones?\n\n\nIMHO those best/worst cases are fine because:\n\n1) best case (job, nlp, year, sequence)\n\nI don't see how we could get anything better for queries on \"sequence\"\nthan this index, because that's literally one of the indexes that would\nbe included in the whole index.\n\nYes, if you need to support queries on additional columns, you might\nneed more indexes, but that's irrelevant - why would anyone define those\nindexes, when the \"worst case\" btree index with all the columns is so\nclose to the best case?\n\n\n2) worst case (job, nlp, year, scan_id, issue_flag, sequence)\n\nI think an index with INCLUDE is entirely irrelevant here. The reason to\nuse INCLUDE is to define UNIQUE index on a subset of columns, but that's\nnot what we need here. I repeated the benchmark with such index, and the\ntiming is ~150ms, so about 50% slower than the simple index. Sorting on\nall columns is clearly beneficial even for the last column.\n\n\nSo I still think those best/worst cases are sensible, and the proposed\nindex would need to beat the worst case. Which seems challenging,\nconsidering how close it is to the best case. Or it might break the best\ncase, if there's some sort of revolutionary way to store the small\nindexes or something like that.\n\nThe fact that there's no size difference between the two cases is mostly\na coincidence, due to the columns being just 2B each, and with wider\nvalues the difference might be substantial, making the gap larger. But\nthen the new index would have to improve on this, but there's no\nproposal on how to do that.\n\n\n> We should try to find a gap between these three cases.\n> For DML queries \n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year\n> INCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence)\n> AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )\n> Because again the proposed index should be just one and cover all 3\n> separate ones. \n> \n> If you agree with these cases I will try to find a bigger time frame to\n> compare these two cases deeper. \n>\n> The issue is not high prio but I strongly believe it can help and can be\n> nice feature for even more complicated cases.\n> \n\nYou don't need my approval to run benchmarks etc. If you believe this is\nbeneficial then just do the tests and you'll see if it makes sense ...\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Mon, 1 Nov 2021 16:03:08 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\n<tomas.vondra@enterprisedb.com> wrote:\n> If I get what you propose, you want to have a \"top\" tree for (job, nlp,\n> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n> then for each subset you want a separate \"small\" trees on each of the\n> other columns, so in this case three trees.\n>\n> Well, the problem with this is pretty obvious - each of the small trees\n> requires separate copies of the leaf pages. And remember, in a btree the\n> internal pages are usually less than 1% of the index, so this pretty\n> much triples the size of the index. And if you insert a row into the\n> index, it has to insert the item pointer into each of the small trees,\n> likely requiring a separate I/O for each.\n>\n> So I'd bet this is not any different from just having three separate\n> indexes - it doesn't save space, doesn't save I/O, nothing.\n\nI agree. In a lot of cases, it's actually useful to define the index\non fewer columns, like (job, nlp, year) or even just (job, nlp) or\neven just (job) because it makes the index so much smaller and that's\npretty important. If you have enough duplicate entries in a (job, nlp,\nyear) index to justify create a (job, nlp, year, sequence) index, the\nnumber of distinct (job, nlp, year) tuples has to be small compared to\nthe number of (job, nlp, year, sequence) tuples - and that means that\nyou wouldn't actually save much by combining your (job, nlp, year,\nsequence) index with a (job, nlp, year, other-stuff) index. As you\nsay, the internal pages aren't the problem.\n\nI don't intend to say that there's no possible use for this kind of\ntechnology. Peter G. says that people are writing research papers\nabout that and they probably wouldn't be doing that unless they'd\nfound some case where it's a big win. But this example seems extremely\nunconvincing.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Mon, 1 Nov 2021 16:06:15 -0400","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\nOn 11/1/21 21:06, Robert Haas wrote:\n> On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\n> <tomas.vondra@enterprisedb.com> wrote:\n>> If I get what you propose, you want to have a \"top\" tree for (job, nlp,\n>> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n>> then for each subset you want a separate \"small\" trees on each of the\n>> other columns, so in this case three trees.\n>>\n>> Well, the problem with this is pretty obvious - each of the small trees\n>> requires separate copies of the leaf pages. And remember, in a btree the\n>> internal pages are usually less than 1% of the index, so this pretty\n>> much triples the size of the index. And if you insert a row into the\n>> index, it has to insert the item pointer into each of the small trees,\n>> likely requiring a separate I/O for each.\n>>\n>> So I'd bet this is not any different from just having three separate\n>> indexes - it doesn't save space, doesn't save I/O, nothing.\n> \n> I agree. In a lot of cases, it's actually useful to define the index\n> on fewer columns, like (job, nlp, year) or even just (job, nlp) or\n> even just (job) because it makes the index so much smaller and that's\n> pretty important. If you have enough duplicate entries in a (job, nlp,\n> year) index to justify create a (job, nlp, year, sequence) index, the\n> number of distinct (job, nlp, year) tuples has to be small compared to\n> the number of (job, nlp, year, sequence) tuples - and that means that\n> you wouldn't actually save much by combining your (job, nlp, year,\n> sequence) index with a (job, nlp, year, other-stuff) index. As you\n> say, the internal pages aren't the problem.\n> \n> I don't intend to say that there's no possible use for this kind of\n> technology. Peter G. says that people are writing research papers\n> about that and they probably wouldn't be doing that unless they'd\n> found some case where it's a big win. But this example seems extremely\n> unconvincing.\n> \n\nI actually looked at the use case mentioned by Peter G, i.e. merged \nindexes with master-detail clustering (see e.g. [1]), but that seems \nlike a rather different thing. The master-detail refers to storing rows \nfrom multiple tables, interleaved in a way that allows faster joins. So \nit's essentially a denormalization tool.\n\nPerhaps there's something we could learn about efficient storage of the \nsmall trees, but I haven't found any papers describing that (I haven't \nspent much time on the search, though).\n\n[1] Algorithms for merged indexes, Goetz Graefe\n https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Mon, 1 Nov 2021 22:15:59 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"Tomas Vondra\n> Are you suggesting those are not the actual best/worst cases and we\n> should use some other indexes? If yes, which ones?\n\nI would say yes.\nIn my case I am not querying only sequence column.\nI have the following cases which I want to optimize.\n1. Select * from Some_table where job = <somthing> and nlp = <something>\nand year = <something> and *scan_id = <something> *\n2. Select * from Some_table where job = <somthing> and nlp = <something>\nand year = <something> and *Issue_flag = <something> *\n3. Select * from Some_table where job = <somthing> and nlp = <something>\nand year = <something> and *sequence = <something> *\nThose are queries that my app send to db that is why I said that from *read\nperspective* our *best case* is 3 separate indexes for\n *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\nnlp, year, issue_flag)* and any other solution like\n (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\nINCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\nconsidered as* worst case *\nI will remind that in real world scenario I have ~50m rows and about *~5k\nrows for each (job, nlp, year )*\n From *write perspective* as far as we want to have only one index our* best\ncase* can be considered any of\n*(job, nlp, year, sequence, Scan_ID, issue_flag)* OR * (job, nlp, year )\nINCLUDE(sequence, Scan_ID, issue_flag) *\nand the* worst case* will be having 3 separate queries like in read\nperspective\n(job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\nyear, issue_flag)\n\nSo I think the comparison that we did is not right because we are comparing\ndifferent/wrong things.\n\nFor right results we need to compare this two cases when we are doing\nrandom queries with 1,2,3 and random writes.\n\n\nвт, 2 нояб. 2021 г. в 01:16, Tomas Vondra <tomas.vondra@enterprisedb.com>:\n\n>\n>\n> On 11/1/21 21:06, Robert Haas wrote:\n> > On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\n> > <tomas.vondra@enterprisedb.com> wrote:\n> >> If I get what you propose, you want to have a \"top\" tree for (job, nlp,\n> >> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n> >> then for each subset you want a separate \"small\" trees on each of the\n> >> other columns, so in this case three trees.\n> >>\n> >> Well, the problem with this is pretty obvious - each of the small trees\n> >> requires separate copies of the leaf pages. And remember, in a btree the\n> >> internal pages are usually less than 1% of the index, so this pretty\n> >> much triples the size of the index. And if you insert a row into the\n> >> index, it has to insert the item pointer into each of the small trees,\n> >> likely requiring a separate I/O for each.\n> >>\n> >> So I'd bet this is not any different from just having three separate\n> >> indexes - it doesn't save space, doesn't save I/O, nothing.\n> >\n> > I agree. In a lot of cases, it's actually useful to define the index\n> > on fewer columns, like (job, nlp, year) or even just (job, nlp) or\n> > even just (job) because it makes the index so much smaller and that's\n> > pretty important. If you have enough duplicate entries in a (job, nlp,\n> > year) index to justify create a (job, nlp, year, sequence) index, the\n> > number of distinct (job, nlp, year) tuples has to be small compared to\n> > the number of (job, nlp, year, sequence) tuples - and that means that\n> > you wouldn't actually save much by combining your (job, nlp, year,\n> > sequence) index with a (job, nlp, year, other-stuff) index. As you\n> > say, the internal pages aren't the problem.\n> >\n> > I don't intend to say that there's no possible use for this kind of\n> > technology. Peter G. says that people are writing research papers\n> > about that and they probably wouldn't be doing that unless they'd\n> > found some case where it's a big win. But this example seems extremely\n> > unconvincing.\n> >\n>\n> I actually looked at the use case mentioned by Peter G, i.e. merged\n> indexes with master-detail clustering (see e.g. [1]), but that seems\n> like a rather different thing. The master-detail refers to storing rows\n> from multiple tables, interleaved in a way that allows faster joins. So\n> it's essentially a denormalization tool.\n>\n> Perhaps there's something we could learn about efficient storage of the\n> small trees, but I haven't found any papers describing that (I haven't\n> spent much time on the search, though).\n>\n> [1] Algorithms for merged indexes, Goetz Graefe\n> https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\n>\n>\n> regards\n>\n> --\n> Tomas Vondra\n> EnterpriseDB: http://www.enterprisedb.com\n> The Enterprise PostgreSQL Company\n>\n\nTomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year )From write perspective as far as we want to have only one index our best case can be considered any of(job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) and the worst case will be having 3 separate queries like in read perspective (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) So I think the comparison that we did is not right because we are comparing different/wrong things.For right results we need to compare this two cases when we are doing random queries with 1,2,3 and random writes.вт, 2 нояб. 2021 г. в 01:16, Tomas Vondra <tomas.vondra@enterprisedb.com>:\n\nOn 11/1/21 21:06, Robert Haas wrote:\n> On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\n> <tomas.vondra@enterprisedb.com> wrote:\n>> If I get what you propose, you want to have a \"top\" tree for (job, nlp,\n>> year), which \"splits\" the data set into subsets of ~5000-7000 rows. And\n>> then for each subset you want a separate \"small\" trees on each of the\n>> other columns, so in this case three trees.\n>>\n>> Well, the problem with this is pretty obvious - each of the small trees\n>> requires separate copies of the leaf pages. And remember, in a btree the\n>> internal pages are usually less than 1% of the index, so this pretty\n>> much triples the size of the index. And if you insert a row into the\n>> index, it has to insert the item pointer into each of the small trees,\n>> likely requiring a separate I/O for each.\n>>\n>> So I'd bet this is not any different from just having three separate\n>> indexes - it doesn't save space, doesn't save I/O, nothing.\n> \n> I agree. In a lot of cases, it's actually useful to define the index\n> on fewer columns, like (job, nlp, year) or even just (job, nlp) or\n> even just (job) because it makes the index so much smaller and that's\n> pretty important. If you have enough duplicate entries in a (job, nlp,\n> year) index to justify create a (job, nlp, year, sequence) index, the\n> number of distinct (job, nlp, year) tuples has to be small compared to\n> the number of (job, nlp, year, sequence) tuples - and that means that\n> you wouldn't actually save much by combining your (job, nlp, year,\n> sequence) index with a (job, nlp, year, other-stuff) index. As you\n> say, the internal pages aren't the problem.\n> \n> I don't intend to say that there's no possible use for this kind of\n> technology. Peter G. says that people are writing research papers\n> about that and they probably wouldn't be doing that unless they'd\n> found some case where it's a big win. But this example seems extremely\n> unconvincing.\n> \n\nI actually looked at the use case mentioned by Peter G, i.e. merged \nindexes with master-detail clustering (see e.g. [1]), but that seems \nlike a rather different thing. The master-detail refers to storing rows \nfrom multiple tables, interleaved in a way that allows faster joins. So \nit's essentially a denormalization tool.\n\nPerhaps there's something we could learn about efficient storage of the \nsmall trees, but I haven't found any papers describing that (I haven't \nspent much time on the search, though).\n\n[1] Algorithms for merged indexes, Goetz Graefe\n https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\n\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company","msg_date":"Tue, 2 Nov 2021 16:04:29 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"\n\nOn 11/2/21 13:04, Hayk Manukyan wrote:\n> Tomas Vondra\n> > Are you suggesting those are not the actual best/worst cases and we\n> > should use some other indexes? If yes, which ones?\n> \n> I would say yes.\n> In my case I am not querying only sequence column.\n> I have the following cases which I want to optimize.\n> 1. Select * from Some_table where job = <somthing> and nlp = <something> \n> and year = <something> and *scan_id = <something> *\n> 2. Select * from Some_table where job = <somthing> and nlp = <something> \n> and year = <something> and *Issue_flag = <something> *\n> 3. Select * from Some_table where job = <somthing> and nlp = <something> \n> and year = <something> and *sequence = <something> *\n> Those are queries that my app send to db that is why I said that from \n> *read perspective* our *best case* is 3 separate indexes for\n> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job, \n> nlp, year, issue_flag)* and any other solution like\n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) \n> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be \n> considered as*worst case *\n\nI already explained why using INCLUDE in this case is the wrong thing to \ndo, it'll harm performance compared to just defining a regular index.\n\n> I will remind that in real world scenario I have ~50m rows and about \n> *~5k rows for each (job, nlp, year )*\n\nWell, maybe this is the problem. We have 50M rows, but the three columns \nhave too many distinct values - (job, nlp, year) defines ~50M groups, so \nthere's only a single row per group. That'd explain why the two indexes \nperform almost equally.\n\nSo I guess you need to modify the data generator so that the data set is \nmore like the case you're trying to improve.\n\n> From *write perspective* as far as we want to have only one index \n> our*best case* can be considered any of\n> *(job, nlp, year, sequence, Scan_ID, issue_flag)* OR *(job, nlp, year ) \n> INCLUDE(sequence, Scan_ID, issue_flag) *\n> and the*worst case* will be having 3 separate queries like in read \n> perspective\n> (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, \n> year, issue_flag)\n> \n\nMaybe. It's true a write with three indexes will require modification to \nthree leaf pages (on average). With a single index we have to modify \njust one leaf page, depending on where the row gets routed.\n\nBut with the proposed \"merged\" index, the row will have to be inserted \ninto three smaller trees. If the trees are large enough, they won't fit \ninto a single leaf page (e.g. the 5000 index tuples is guaranteed to \nneed many pages, even if you use some smart encoding). So the write will \nlikely need to modify at least 3 leaf pages, getting much closer to \nthree separate indexes. At which point you could just use three indexes.\n\n> So I think the comparison that we did is not right because we are \n> comparing different/wrong things.\n> > For right results we need to compare this two cases when we are doing\n> random queries with 1,2,3 and random writes.\n> \n\nI'm not going to spend any more time on tweaking the benchmark, but if \nyou tweak it to demonstrate the difference / benefits I'll run it again \non my machine etc.\n\nregards\n\n-- \nTomas Vondra\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n","msg_date":"Tue, 2 Nov 2021 15:03:06 +0100","msg_from":"Tomas Vondra <tomas.vondra@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:\n\n> Tomas Vondra\n> > Are you suggesting those are not the actual best/worst cases and we\n> > should use some other indexes? If yes, which ones?\n>\n> I would say yes.\n> In my case I am not querying only sequence column.\n> I have the following cases which I want to optimize.\n> 1. Select * from Some_table where job = <somthing> and nlp = <something>\n> and year = <something> and *scan_id = <something> *\n> 2. Select * from Some_table where job = <somthing> and nlp = <something>\n> and year = <something> and *Issue_flag = <something> *\n> 3. Select * from Some_table where job = <somthing> and nlp = <something>\n> and year = <something> and *sequence = <something> *\n> Those are queries that my app send to db that is why I said that from *read\n> perspective* our *best case* is 3 separate indexes for\n> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\n> nlp, year, issue_flag)* and any other solution like\n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\n> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\n> considered as* worst case *\n> I will remind that in real world scenario I have ~50m rows and about *~5k\n> rows for each (job, nlp, year )*\n>\n\n So you get 50M rows /5K rows = 10K times selectivity, when you select on\njob = <somthing> and nlp = <something> and year = <something> which is\nenormous. Then you should select some of the 5K rows left, which is\nexpected to be pretty fast on bitmap index scan or INCLUDE column\nfiltering. It confirms Tomas's experiment\n\n pgbench -n -f q4.sql -T 60\n\n106 ms vs 109 ms\n\nfits your case pretty well. You get absolutely negligible difference\nbetween best and worst case and certainly you don't need anything more than\njust plain index for 3 columns, you even don't need INCLUDE index.\n\n From what I read I suppose that this feature indeed doesn't based on the\nreal need. If you suppose it is useful please feel free to make and post\nhere some measurements that proves your point.\n\n\n\n\n-- \nBest regards,\nPavel Borisov\n\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\n\nвт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:Tomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year ) So you get 50M rows /5K rows = 10K times selectivity, when you select on job = <somthing> and nlp = <something> and year = <something> which is enormous. Then you should select some of the 5K rows left, which is expected to be pretty fast on bitmap index scan or INCLUDE column filtering. It confirms Tomas's experiment pgbench -n -f q4.sql -T 60106 ms vs 109 msfits your case pretty well. You get absolutely negligible difference between best and worst case and certainly you don't need anything more than just plain index for 3 columns, you even don't need INCLUDE index.From what I read I suppose that this feature indeed doesn't based on the real need. If you suppose it is useful please feel free to make and post here some measurements that proves your point.-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com","msg_date":"Tue, 2 Nov 2021 18:04:14 +0400","msg_from":"Pavel Borisov <pashkin.elfe@gmail.com>","msg_from_op":false,"msg_subject":"Re: Feature request for adoptive indexes"},{"msg_contents":"Hi All\n\nI did final research and saw that the difference between best and worst\ncases is indeed really small.\nI want to thank you guys for your time and efforts.\n\nBest regards.\n\n\nвт, 2 нояб. 2021 г. в 18:04, Pavel Borisov <pashkin.elfe@gmail.com>:\n\n> вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:\n>\n>> Tomas Vondra\n>> > Are you suggesting those are not the actual best/worst cases and we\n>> > should use some other indexes? If yes, which ones?\n>>\n>> I would say yes.\n>> In my case I am not querying only sequence column.\n>> I have the following cases which I want to optimize.\n>> 1. Select * from Some_table where job = <somthing> and nlp = <something>\n>> and year = <something> and *scan_id = <something> *\n>> 2. Select * from Some_table where job = <somthing> and nlp = <something>\n>> and year = <something> and *Issue_flag = <something> *\n>> 3. Select * from Some_table where job = <somthing> and nlp = <something>\n>> and year = <something> and *sequence = <something> *\n>> Those are queries that my app send to db that is why I said that from *read\n>> perspective* our *best case* is 3 separate indexes for\n>> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\n>> nlp, year, issue_flag)* and any other solution like\n>> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\n>> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\n>> considered as* worst case *\n>> I will remind that in real world scenario I have ~50m rows and about *~5k\n>> rows for each (job, nlp, year )*\n>>\n>\n> So you get 50M rows /5K rows = 10K times selectivity, when you select on\n> job = <somthing> and nlp = <something> and year = <something> which is\n> enormous. Then you should select some of the 5K rows left, which is\n> expected to be pretty fast on bitmap index scan or INCLUDE column\n> filtering. It confirms Tomas's experiment\n>\n> pgbench -n -f q4.sql -T 60\n>\n> 106 ms vs 109 ms\n>\n> fits your case pretty well. You get absolutely negligible difference\n> between best and worst case and certainly you don't need anything more than\n> just plain index for 3 columns, you even don't need INCLUDE index.\n>\n> From what I read I suppose that this feature indeed doesn't based on the\n> real need. If you suppose it is useful please feel free to make and post\n> here some measurements that proves your point.\n>\n>\n>\n>\n> --\n> Best regards,\n> Pavel Borisov\n>\n> Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>\n>\n\nHi AllI did final research and saw that the difference between best and worst cases is indeed really small.I want to thank you guys for your time and efforts.Best regards.вт, 2 нояб. 2021 г. в 18:04, Pavel Borisov <pashkin.elfe@gmail.com>:вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:Tomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year ) So you get 50M rows /5K rows = 10K times selectivity, when you select on job = <somthing> and nlp = <something> and year = <something> which is enormous. Then you should select some of the 5K rows left, which is expected to be pretty fast on bitmap index scan or INCLUDE column filtering. It confirms Tomas's experiment pgbench -n -f q4.sql -T 60106 ms vs 109 msfits your case pretty well. You get absolutely negligible difference between best and worst case and certainly you don't need anything more than just plain index for 3 columns, you even don't need INCLUDE index.From what I read I suppose that this feature indeed doesn't based on the real need. If you suppose it is useful please feel free to make and post here some measurements that proves your point.-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com","msg_date":"Fri, 5 Nov 2021 15:17:49 +0400","msg_from":"Hayk Manukyan <manukyantt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Feature request for adoptive indexes"}],"string":"[\n {\n \"msg_contents\": \"Hi everyone. I want to do some feature request regarding indexes, as far as\\nI know this kind of functionality doesn't exists in Postgres. Here is my\\nproblem :\\nI need to create following indexes:\\n Create index job_nlp_year_scan on ingest_scans_stageing\\n(`job`,`nlp`,`year`,`scan_id`);\\n Create index job_nlp_year_issue_flag on ingest_scans_stageing\\n(`job`,`nlp`,`year`,`issue_flag`);\\n Create index job_nlp_year_sequence on ingest_scans_stageing\\n(`job`,`nlp`,`year`,`sequence`);\\nAs you can see the first 3 columns are the same (job, nlp, year). so if I\\ncreate 3 different indexes db should manage same job_nlp_year structure 3\\ntimes.\\nThe Data Structure that I think which can be efficient in this kind of\\nscenarios is to have 'Adaptive Index' which will be something like\\nCreate index job_nlp_year on ingest_scans_stageing\\n(`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\\nAnd depend on query it will use or job_nlp_year_scan or\\njob_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and one\\nof ( `issue_flag` , `scan_id` , `sequence` )\\nFor more description please feel free to refer me\\n\\nHi everyone. I want to do some feature request regarding indexes, as far asI know this kind of functionality doesn't exists in Postgres. Here is myproblem :I need to create following indexes: Create index job_nlp_year_scan on ingest_scans_stageing(`job`,`nlp`,`year`,`scan_id`); Create index job_nlp_year_issue_flag on ingest_scans_stageing(`job`,`nlp`,`year`,`issue_flag`); Create index job_nlp_year_sequence on ingest_scans_stageing(`job`,`nlp`,`year`,`sequence`);As you can see the first 3 columns are the same (job, nlp, year). so if Icreate 3 different indexes db should manage same job_nlp_year structure 3times.The Data Structure that I think which can be efficient in this kind ofscenarios is to have 'Adaptive Index' which will be something likeCreate index job_nlp_year on ingest_scans_stageing(`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));And depend on query it will use or job_nlp_year_scan orjob_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and oneof ( `issue_flag` , `scan_id` , `sequence` )For more description please feel free to refer me\",\n \"msg_date\": \"Mon, 25 Oct 2021 18:07:18 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 10/25/21 16:07, Hayk Manukyan wrote:\\n> Hi everyone. I want to do some feature request regarding indexes, as far as\\n> I know this kind of functionality doesn't exists in Postgres. Here is my\\n> problem :\\n> I need to create following indexes:\\n> Create index job_nlp_year_scan on ingest_scans_stageing\\n> (`job`,`nlp`,`year`,`scan_id`);\\n> Create index job_nlp_year_issue_flag on ingest_scans_stageing\\n> (`job`,`nlp`,`year`,`issue_flag`);\\n> Create index job_nlp_year_sequence on ingest_scans_stageing\\n> (`job`,`nlp`,`year`,`sequence`);\\n> As you can see the first 3 columns are the same (job, nlp, year). so if I\\n> create 3 different indexes db should manage same job_nlp_year structure 3\\n> times.\\n> The Data Structure that I think which can be efficient in this kind of\\n> scenarios is to have 'Adaptive Index' which will be something like\\n> Create index job_nlp_year on ingest_scans_stageing\\n> (`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\\n> And depend on query it will use or job_nlp_year_scan or\\n> job_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and one\\n> of ( `issue_flag` , `scan_id` , `sequence` )\\n> For more description please feel free to refer me\\n\\nIt's not very clear what exactly would the \\\"adaptive index\\\" do, except \\nthat it'd have all three columns. Clearly, the three columns can't be \\nconsidered for ordering etc. but need to be in the index somehow. So why \\nwouldn't it be enough to either to create an index with all six columns?\\n\\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag, \\nsequence);\\n\\nor possibly with the columns just \\\"included\\\" in the index:\\n\\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year) INCLUDE (scan_id, \\nissue_flag, sequence);\\n\\nIf this does not work, you either need to explain more clearly what \\nexactly the adaptive indexes does, or show queries that can't benefit \\nfrom these existing features.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Oct 2021 17:33:36 +0200\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"ok. here is the deal if I have the following index with 6 column\\n\\nCREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\\nsequence);\\n\\nI need to specify all 6 columns in where clause in order to fully use this\\nindex.\\nIt will not be efficient in cases when I have 4 condition in where clause\\nalso I should follow the order of columns.\\nIn case of INCLUDE the 3 columns just will be in index but will not be\\nstructured as index so it will have affect only if In select I will have\\nthat 6 columns nothing more.\\n\\nIn my case I have table with ~15 columns\\nIn my application I have to do a lot of queries with following where\\nclauses\\n\\n1. where job = <something> and nlp = <something> and year = <something>\\nand SCAN_ID = <something>\\n2. where job = <something> and nlp = <something> and year = <something>\\nand ISSUE_FLAG = <something>\\n3. where job = <something> and nlp = <something> and year = <something>\\nand SEQUENCE = <something>\\n\\nI don't want to index just on job, nlp, year because for each job, nlp,\\nyear I have approximately 5000-7000 rows ,\\noverall table have ~50m rows so it is partitioned by job as well. So if I\\nbuild 3 separate indexes it will be huge resource.\\nSo I am thinking of having one index which will be job, nlp, year and the\\n4-th layer will be other columns not just included but also in B-tree\\nstructure.\\nTo visualize it will be something like this:\\n[image: image.png]\\nThe red part is ordinary index with nested b-trees ant the yellow part is\\nadaptive part so depends on\\nwhere clause optimizer can decide which direction (leaf, b-tree whatever)\\nto chose.\\nIn this case I will have one index and will manage red part only once for\\nall three cases.\\nThose it make sense ?\\nIf you need more discussion we can have short call I will try to explain\\nyou in more detailed way.\\n\\nbest regards\\n\\nпн, 25 окт. 2021 г. в 19:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\\n\\n> Hi,\\n>\\n> On 10/25/21 16:07, Hayk Manukyan wrote:\\n> > Hi everyone. I want to do some feature request regarding indexes, as far\\n> as\\n> > I know this kind of functionality doesn't exists in Postgres. Here is my\\n> > problem :\\n> > I need to create following indexes:\\n> > Create index job_nlp_year_scan on ingest_scans_stageing\\n> > (`job`,`nlp`,`year`,`scan_id`);\\n> > Create index job_nlp_year_issue_flag on ingest_scans_stageing\\n> > (`job`,`nlp`,`year`,`issue_flag`);\\n> > Create index job_nlp_year_sequence on ingest_scans_stageing\\n> > (`job`,`nlp`,`year`,`sequence`);\\n> > As you can see the first 3 columns are the same (job, nlp, year). so if I\\n> > create 3 different indexes db should manage same job_nlp_year structure 3\\n> > times.\\n> > The Data Structure that I think which can be efficient in this kind of\\n> > scenarios is to have 'Adaptive Index' which will be something like\\n> > Create index job_nlp_year on ingest_scans_stageing\\n> > (`job`,`nlp`,`year`,(`issue_flag`,`scan_id`, `sequence`));\\n> > And depend on query it will use or job_nlp_year_scan or\\n> > job_nlp_year_issue_flag , or job_nlp_year_sequence ( job, nlp, year and\\n> one\\n> > of ( `issue_flag` , `scan_id` , `sequence` )\\n> > For more description please feel free to refer me\\n>\\n> It's not very clear what exactly would the \\\"adaptive index\\\" do, except\\n> that it'd have all three columns. Clearly, the three columns can't be\\n> considered for ordering etc. but need to be in the index somehow. So why\\n> wouldn't it be enough to either to create an index with all six columns?\\n>\\n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\\n> sequence);\\n>\\n> or possibly with the columns just \\\"included\\\" in the index:\\n>\\n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year) INCLUDE (scan_id,\\n> issue_flag, sequence);\\n>\\n> If this does not work, you either need to explain more clearly what\\n> exactly the adaptive indexes does, or show queries that can't benefit\\n> from these existing features.\\n>\\n>\\n> regards\\n>\\n> --\\n> Tomas Vondra\\n> EnterpriseDB: http://www.enterprisedb.com\\n> The Enterprise PostgreSQL Company\\n>\",\n \"msg_date\": \"Tue, 26 Oct 2021 10:49:31 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 10/26/21 8:49 AM, Hayk Manukyan wrote:\\n> ok. here is the deal if I have the following index with 6 column\\n> \\n> CREATE INDEX ON job_nlp_year_scan (job, nlp, year, scan_id, issue_flag,\\n> sequence);\\n> \\n> I need to specify all 6 columns in where clause in order to fully use\\n> this index.\\n\\nWhat do you mean by \\\"fully use this index\\\"? Yes, the query may use just\\nsome of the columns and there will be a bit of overhead, but I doubt\\nit'll be measurable.\\n\\n> It will not be efficient in cases when I have 4 condition in where\\n> clause also I should follow the order of columns.\\n\\nSo, do some experiments and show us what the difference is. Create an\\nindex on the 4 and 6 columns, and measure timings for a query with just\\nthe 4 columns.\\n\\n> In case of INCLUDE the 3 columns just will be in index but will not be\\n> structured as index so it will have affect only if In select I will have\\n> that 6 columns nothing more.\\n> \\n> In my case I have table with ~15 columns\\n> In my application I have to do a lot of queries with following where\\n> clauses \\n> \\n> 1. where job = <something> and nlp = <something> and year = <something>\\n> and SCAN_ID = <something>\\n> 2. where job = <something> and nlp = <something> and year = <something>\\n> and ISSUE_FLAG = <something>\\n> 3. where job = <something> and nlp = <something> and year = <something>\\n> and SEQUENCE = <something>\\n> \\n> I don't want to index just on job, nlp, year because for each job,\\n> nlp, year I have approximately 5000-7000 rows ,\\n> overall table have ~50m rows so it is partitioned by job as well. So if\\n> I build 3 separate indexes it will be huge resource.\\n> So I am thinking of having one index which will be job, nlp, year and\\n> the 4-th layer will be other columns not just included but also in\\n> B-tree structure. \\n> To visualize it will be something like this:\\n> image.png\\n> The red part is ordinary index with nested b-trees ant the yellow part\\n> is adaptive part so depends on\\n> where clause optimizer can decide which direction (leaf, b-tree\\n> whatever) to chose.\\n> In this case I will have one index and will manage red part only once\\n> for all three cases.\\n> Those it make sense ? \\n\\nIf I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\nyear), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\nthen for each subset you want a separate \\\"small\\\" trees on each of the\\nother columns, so in this case three trees.\\n\\nWell, the problem with this is pretty obvious - each of the small trees\\nrequires separate copies of the leaf pages. And remember, in a btree the\\ninternal pages are usually less than 1% of the index, so this pretty\\nmuch triples the size of the index. And if you insert a row into the\\nindex, it has to insert the item pointer into each of the small trees,\\nlikely requiring a separate I/O for each.\\n\\nSo I'd bet this is not any different from just having three separate\\nindexes - it doesn't save space, doesn't save I/O, nothing.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 17:08:59 +0200\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"I've already answered OP but it seems in the wrong thread, so I copy it\\nhere:\\n\\nI think now in many cases you can effectively use covering index to have\\nfast index-only scans without index duplication. It will help if you don't\\nhave great selectivity on the last column (most probably you don't). E.g.:\\n\\nCREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`,\\n`issue_flag`, `sequence`)\\n\\nBut I consider the feature can be useful when there is a very little\\nselectivity in the first index columns. I.e. if (job`,`nlp`,`year') has\\nmany repeats and the most selection is done in the last column. I am not\\nsure how often this can arise but in general, I see it as a useful b-tree\\ngeneralization.\\n\\nI'm not sure how it should be done. In my view, we need to add an ordered\\nposting tree as a leaf element if b-tree and now we have index storage only\\nfor tuples. The change of on-disk format was previously not easy in nbtree\\nand if we consider the change, we need an extra bit to mark posting trees\\namong index tuples. Maybe it could be done in a way similar to deduplicated\\ntuples if some bits in the tuple header are still could be freed.\\n\\nThoughts?\\n\\nIf I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n> then for each subset you want a separate \\\"small\\\" trees on each of the\\n> other columns, so in this case three trees.\\n>\\n> Well, the problem with this is pretty obvious - each of the small trees\\n> requires separate copies of the leaf pages. And remember, in a btree the\\n> internal pages are usually less than 1% of the index, so this pretty\\n> much triples the size of the index. And if you insert a row into the\\n> index, it has to insert the item pointer into each of the small trees,\\n> likely requiring a separate I/O for each.\\n>\\n> So I'd bet this is not any different from just having three separate\\n> indexes - it doesn't save space, doesn't save I/O, nothing.\\n>\\n\\nTomas, I really think we should not try realizing this feature using\\nexisting index pages that contain only tuples. You are right, it will cause\\nlarge overhead. If instead we decide and succeed in creating \\\"posting\\ntrees\\\" as a new on-disk page entry type we can have an index with space\\ncomparable to the abovementioned covering index but with sorting of values\\nin these trees (i.e. all values are sorted, and \\\"key\\\" ones).\\n\\n-- \\nBest regards,\\nPavel Borisov\\n\\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\\n\\nI've already answered OP but it seems in the wrong thread, so I copy it here:I think now in many cases you can effectively use covering index to have fast index-only scans without index duplication. It will help if you don't have great selectivity on the last column (most probably you don't). E.g.:CREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`, `issue_flag`, `sequence`)But I consider the feature can be useful when there is a very little selectivity in the first index columns. I.e. if (job`,`nlp`,`year') has many repeats and the most selection is done in the last column. I am not sure how often this can arise but in general, I see it as a useful b-tree generalization.I'm not sure how it should be done. In my view, we need to add an ordered posting tree as a leaf element if b-tree and now we have index storage only for tuples. The change of on-disk format was previously not easy in nbtree and if we consider the change, we need an extra bit to mark posting trees among index tuples. Maybe it could be done in a way similar to deduplicated tuples if some bits in the tuple header are still could be freed.Thoughts? If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\nyear), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\nthen for each subset you want a separate \\\"small\\\" trees on each of the\\nother columns, so in this case three trees.\\n\\nWell, the problem with this is pretty obvious - each of the small trees\\nrequires separate copies of the leaf pages. And remember, in a btree the\\ninternal pages are usually less than 1% of the index, so this pretty\\nmuch triples the size of the index. And if you insert a row into the\\nindex, it has to insert the item pointer into each of the small trees,\\nlikely requiring a separate I/O for each.\\n\\nSo I'd bet this is not any different from just having three separate\\nindexes - it doesn't save space, doesn't save I/O, nothing. Tomas, I really think we should not try realizing this feature using existing index pages that contain only tuples. You are right, it will cause large overhead. If instead we decide and succeed in creating \\\"posting trees\\\" as a new on-disk page entry type we can have an index with space comparable to the abovementioned covering index but with sorting of values in these trees (i.e. all values are sorted, and \\\"key\\\" ones).-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com\",\n \"msg_date\": \"Tue, 26 Oct 2021 23:39:20 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 10/26/21 21:39, Pavel Borisov wrote:\\n> I've already answered OP but it seems in the wrong thread, so I copy it \\n> here:\\n> \\n> I think now in many cases you can effectively use covering index to have \\n> fast index-only scans without index duplication. It will help if you \\n> don't have great selectivity on the last column (most probably you \\n> don't). E.g.:\\n> \\n> CREATE INDEX ON table_name (`job`,`nlp`,`year`) INCLUDE (`scan_id`, \\n> `issue_flag`, `sequence`)\\n> \\n> But I consider the feature can be useful when there is a very little \\n> selectivity in the first index columns. I.e. if (job`,`nlp`,`year') has \\n> many repeats and the most selection is done in the last column. I am not \\n> sure how often this can arise but in general, I see it as a useful \\n> b-tree generalization.\\n> \\n> I'm not sure how it should be done. In my view, we need to add an \\n> ordered posting tree as a leaf element if b-tree and now we have index \\n> storage only for tuples. The change of on-disk format was previously not \\n> easy in nbtree and if we consider the change, we need an extra bit to \\n> mark posting trees among index tuples. Maybe it could be done in a way \\n> similar to deduplicated tuples if some bits in the tuple header are \\n> still could be freed.\\n> \\n> Thoughts?\\n> \\n> If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n> then for each subset you want a separate \\\"small\\\" trees on each of the\\n> other columns, so in this case three trees.\\n> \\n> Well, the problem with this is pretty obvious - each of the small trees\\n> requires separate copies of the leaf pages. And remember, in a btree the\\n> internal pages are usually less than 1% of the index, so this pretty\\n> much triples the size of the index. And if you insert a row into the\\n> index, it has to insert the item pointer into each of the small trees,\\n> likely requiring a separate I/O for each.\\n> \\n> So I'd bet this is not any different from just having three separate\\n> indexes - it doesn't save space, doesn't save I/O, nothing.\\n> \\n> Tomas, I really think we should not try realizing this feature using \\n> existing index pages that contain only tuples. You are right, it will \\n> cause large overhead. If instead we decide and succeed in creating \\n> \\\"posting trees\\\" as a new on-disk page entry type we can have an index \\n> with space comparable to the abovementioned covering index but with \\n> sorting of values in these trees (i.e. all values are sorted, and \\\"key\\\" \\n> ones).\\n> \\n\\nWell, there was no explanation about how it could/should be implemented, \\nand maybe there is some elaborate way to handle the \\\"posting trees\\\" that \\nI can't quite think of (at least not in the btree context).\\n\\nI'm still rather skeptical about it - for such feature to be useful the \\nprefix columns must not be very selective, i.e. the posting trees are \\nexpected to be fairly large (e.g. 5-7k rows). It pretty much has to to \\nrequire multiple (many) index pages, in order for the \\\"larger\\\" btree \\nindex to be slower. And at that point I'd expect the extra overhead to \\nbe worse than simply defining multiple simple indexes.\\n\\nA simple experiment would be to measure timing for queries with a \\ncondition on \\\"sequence\\\" using two indexes:\\n\\n1) (job, nlp, year, sequence)\\n2) (job, nlp, year, scan_id, issue_flag, sequence)\\n\\nThe (1) index is \\\"optimal\\\" i.e. there's unlikely to be a better index \\nfor this query, at least no tree-like. (2) is something like the \\\"worst\\\" \\ncase index that we can use for this query.\\n\\nFor the new feature to be useful, two things would need to be true:\\n\\n* query with (2) is much slower than (1)\\n* the new index would need to be close to (1)\\n\\nObviously, if the new index is slower than (2), it's mostly useless \\nright off the bat. And it probably can't be faster than (1) in practice, \\nas it still is basically a btree index (at least the top half).\\n\\nSo I'd expect the performance to be somewhere between (1) and (2), but \\nif (2) is very close to (1) - which I'd bet it is - then the potential \\nbenefit is also pretty small.\\n\\nPerhaps I'm entirely wrong and there's a new type of index, better \\nsuited for cases similar to this. The \\\"posting tree\\\" reference actually \\nmade me thinking that maybe btree_gin might be applicable here?\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 22:43:22 +0200\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Oct 26, 2021, at 1:43 PM, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote:\\n> \\n> I'm still rather skeptical about it - for such feature to be useful the prefix columns must not be very selective, i.e. the posting trees are expected to be fairly large (e.g. 5-7k rows). It pretty much has to to require multiple (many) index pages, in order for the \\\"larger\\\" btree index to be slower. And at that point I'd expect the extra overhead to be worse than simply defining multiple simple indexes.\\n\\nFor three separate indexes, an update or delete of a single row in the indexed table would surely require changing at least three pages in the indexes. For some as-yet-ill-defined combined index type, perhaps the three entries in the index would fall on the same index page often enough to reduce the I/O cost of the action? This is all hard to contemplate without a more precise description of the index algorithm.\\n\\nPerhaps the OP might want to cite a paper describing a particular index algorithm for us to review?\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 15:08:37 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"Mark Dilger <mark.dilger@enterprisedb.com> writes:\\n> For three separate indexes, an update or delete of a single row in the indexed table would surely require changing at least three pages in the indexes. For some as-yet-ill-defined combined index type, perhaps the three entries in the index would fall on the same index page often enough to reduce the I/O cost of the action?\\n\\nOf course, we have that today from the solution of one index with the\\nextra columns \\\"included\\\". I think the OP has completely failed to make\\nany case why that's not a good enough approach.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 18:45:36 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 3:45 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> Of course, we have that today from the solution of one index with the\\n> extra columns \\\"included\\\". I think the OP has completely failed to make\\n> any case why that's not a good enough approach.\\n\\nI think that the design that the OP is talking about (adaptive\\nindexes, AKA merged indexes with master detail clustering) have been\\nthe subject of certain research papers. As far as I know nothing like\\nthat has ever been implemented in a real DB system.\\n\\nIt seems like a daunting project, primarily because of the concurrency\\ncontrol considerations. It's no coincidence that GIN indexes (which\\nhave some of the same issues) only support lossy index scans. Lossy\\nscans don't seem to be compatible with adaptive indexes, since the\\nwhole point is to have multiple distinct \\\"logical indexes\\\" with a\\ncommon prefix, but only one physical index, with clustering. I think\\nyou'd need something like ARIES KVL for concurrency control, just for\\nstarters. Even that is something that won't work with anything like\\ncurrent Postgres.\\n\\nIt's roughly the same story that we see with generalizing TIDs at the\\ntableam level. People tend to imagine that it's basically just a\\nmatter of coming up with the right index AM data structure, but that's\\nactually just the easy part.\\n\\n-- \\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 16:30:52 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \">\\n> It's no coincidence that GIN indexes (which\\n> have some of the same issues) only support lossy index scans.\\n>\\nAFAIK Gin is lossy for phrase queries as we don't store word position in\\nthe posting list. For purely logical queries, where position doesn't\\nmatter, it's not lossy.\\n\\nOne more consideration against the proposal is that if we want to select\\nwith more than one \\\"suffix\\\" columns in the WHERE clause, effectively we\\nwill have a join of two separate index scans. And as we consider suffix\\ncolumns to be highly selective, and prefix columns are weakly selective,\\nthen it could be very slow.\\n\\nJust some ideas on the topic which may not be connected to OP proposal (Not\\nsure whether should we implement them as a part of nbtree) :\\n\\n1. If prefix columns have low selectivity it may be good if we have some\\nattribute-level deduplication only for prefix columns.\\n2. If we have several suffix columns, it might be a good idea is to treat\\nthem as an n-dimensional space and define some R-tree or Quad-tree on top\\nof them (using GiST, SpGIST).\\n\\n-- \\nBest regards,\\nPavel Borisov\\n\\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\\n\\nIt's no coincidence that GIN indexes (which\\nhave some of the same issues) only support lossy index scans. AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.One more consideration against the proposal is that if we want to select with more than one \\\"suffix\\\" columns in the WHERE clause, effectively we will have a join of two separate index scans. And as we consider suffix columns to be highly selective, and prefix columns are weakly selective, then it could be very slow. Just some ideas on the topic which may not be connected to OP proposal (Not sure whether should we implement them as a part of nbtree) :1. If prefix columns have low selectivity it may be good if we have some attribute-level deduplication only for prefix columns.2. If we have several suffix columns, it might be a good idea is to treat them as an n-dimensional space and define some R-tree or Quad-tree on top of them (using GiST, SpGIST).-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com\",\n \"msg_date\": \"Wed, 27 Oct 2021 12:02:23 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com> wrote:\\n> AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.\\n\\nGIN is always lossy, in the sense that it provides only a\\ngingetbitmap() routine -- there is no gingettuple() routine. I believe\\nthat this is fundamental to the overall design of GIN. It would be\\nvery difficult to add useful gingettuple() functionality now, since\\nGIN already relies on lossiness to avoid race conditions.\\n\\nHere's an example of the problems that \\\"adding gingettuple()\\\" would\\nrun into: Today, an index's pending list entries can be merged\\nconcurrently with the entry tree, without worrying about returning the\\nsame tuples twice. This is only safe/correct because GIN only supports\\nbitmap index scans. Without that, you need some other mechanism to\\nmake it safe -- ISTM you must \\\"logically lock\\\" the index structure,\\nusing ARIES/KVL style key value locks, or something along those lines.\\n\\n-- \\nPeter Geoghegan\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 09:10:32 -0700\",\n \"msg_from\": \"Peter Geoghegan <pg@bowt.ie>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"Hi all\\nFirst of all thank you all for fast and rich responses, that is really nice.\\nI don't have that deep knowledge of how postgres works under the hood so I\\nwill try to explain more user side.\\nI want to refer for some points mentioned above.\\n - First INCLUDE statement mostly eliminates the necessity to refer to a\\nclustered index or table to get columns that do not exist in the index. So\\nfiltering upon columns in INCLUDE statement will not be performant. It can\\ngive some very little performance if we include additional columns but it\\nis not in level to compare with indexed one. I believe this not for this\\ncase\\n- Tomas Vondra's Assumption that adaptive should be something between this\\ntwo\\n1) (job, nlp, year, sequence)\\n2) (job, nlp, year, scan_id, issue_flag, sequence)\\nis completely valid. I have made fairly small demo with this index\\ncomparison and as I can see the difference is noticeable. Here is git repo\\nand results\\n<https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/results.md>\\n,\\nI had no much time to do significant one sorry for that ))\\n - regarding data structure side of things by Pavel Borisov.\\nI also think that different data structure will be needed. Not sure exactly\\nat this point which kind of data structure but I will try to explain it\\nhere.\\n<https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/data_structure.md>\\n\\nbest regards\\n\\n\\nср, 27 окт. 2021 г. в 20:10, Peter Geoghegan <pg@bowt.ie>:\\n\\n> On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com>\\n> wrote:\\n> > AFAIK Gin is lossy for phrase queries as we don't store word position in\\n> the posting list. For purely logical queries, where position doesn't\\n> matter, it's not lossy.\\n>\\n> GIN is always lossy, in the sense that it provides only a\\n> gingetbitmap() routine -- there is no gingettuple() routine. I believe\\n> that this is fundamental to the overall design of GIN. It would be\\n> very difficult to add useful gingettuple() functionality now, since\\n> GIN already relies on lossiness to avoid race conditions.\\n>\\n> Here's an example of the problems that \\\"adding gingettuple()\\\" would\\n> run into: Today, an index's pending list entries can be merged\\n> concurrently with the entry tree, without worrying about returning the\\n> same tuples twice. This is only safe/correct because GIN only supports\\n> bitmap index scans. Without that, you need some other mechanism to\\n> make it safe -- ISTM you must \\\"logically lock\\\" the index structure,\\n> using ARIES/KVL style key value locks, or something along those lines.\\n>\\n> --\\n> Peter Geoghegan\\n>\\n\\nHi allFirst of all thank you all for fast and rich responses, that is really nice.I don't have that deep knowledge of how postgres works under the hood so I will try to explain more user side.I want to refer for some points mentioned above. - First INCLUDE statement mostly eliminates the necessity to refer to a clustered index or table to get columns that do not exist in the index. So filtering upon columns in INCLUDE statement will not be performant. It can give some very little performance if we include additional columns but it is not in level to compare with indexed one. I believe this not for this case- Tomas Vondra's Assumption that adaptive should be something between this two 1) (job, nlp, year, sequence)2) (job, nlp, year, scan_id, issue_flag, sequence) is completely valid. I have made fairly small demo with this index comparison and as I can see the difference is noticeable. Here is git repo and results , I had no much time to do significant one sorry for that )) - regarding data structure side of things by Pavel Borisov. I also think that different data structure will be needed. Not sure exactly at this point which kind of data structure but I will try to explain it here.best regards ср, 27 окт. 2021 г. в 20:10, Peter Geoghegan <pg@bowt.ie>:On Wed, Oct 27, 2021 at 1:02 AM Pavel Borisov <pashkin.elfe@gmail.com> wrote:\\n> AFAIK Gin is lossy for phrase queries as we don't store word position in the posting list. For purely logical queries, where position doesn't matter, it's not lossy.\\n\\nGIN is always lossy, in the sense that it provides only a\\ngingetbitmap() routine -- there is no gingettuple() routine. I believe\\nthat this is fundamental to the overall design of GIN. It would be\\nvery difficult to add useful gingettuple() functionality now, since\\nGIN already relies on lossiness to avoid race conditions.\\n\\nHere's an example of the problems that \\\"adding gingettuple()\\\" would\\nrun into: Today, an index's pending list entries can be merged\\nconcurrently with the entry tree, without worrying about returning the\\nsame tuples twice. This is only safe/correct because GIN only supports\\nbitmap index scans. Without that, you need some other mechanism to\\nmake it safe -- ISTM you must \\\"logically lock\\\" the index structure,\\nusing ARIES/KVL style key value locks, or something along those lines.\\n\\n-- \\nPeter Geoghegan\",\n \"msg_date\": \"Fri, 29 Oct 2021 17:32:37 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"On 10/29/21 15:32, Hayk Manukyan wrote:\\n> Hi all\\n> First of all thank you all for fast and rich responses, that is really nice.\\n> I don't have that deep knowledge of how postgres works under the hood \\n> so I will try to explain more user side.\\n> I want to refer for some points mentioned above.\\n> - First INCLUDE statement mostly eliminates the necessity to refer to \\n> a clustered index or table to get columns that do not exist in the \\n> index. So filtering upon columns in INCLUDE statement will not be \\n> performant. It can give some very little performance if we include \\n> additional columns but it is not in level to compare with indexed one. I \\n> believe this not for this case\\n> - Tomas Vondra's Assumption that adaptive should be something between \\n> this two\\n> 1) (job, nlp, year, sequence)\\n> 2) (job, nlp, year, scan_id, issue_flag, sequence)\\n> is completely valid. I have made fairly small demo with this index \\n> comparison and as I can see the difference is noticeable. Here is git \\n> repo and results \\n> <https://github.com/HaykManukyanAvetiky/index_comparition/blob/main/results.md> , \\n> I had no much time to do significant one sorry for that ))\\n\\nI find those results entirely unconvincing, or maybe even suspicious.\\n\\nI used the script to create the objects, and the index sizes are:\\n\\n Name | Size\\n ------------------------------------------+---------\\n job_nlp_year_scan_id_issue_flag_sequence | 1985 MB\\n job_nlp_year_sequence | 1985 MB\\n\\nSo there's no actual difference, most likely due to alignment making up \\nfor the two smalling columns.\\n\\nAnd if I randomize the queries instead of running them with the same \\nparameters over and over (see the attached scripts), then an average of \\n10 runs, each 60s long, the results are (after a proper warmup)\\n\\n pgbench -n -f q4.sql -T 60\\n\\n 4 columns: 106 ms\\n 6 columns: 109 ms\\n\\nSo there's like 3% difference between the two cases, and even that might \\nbe just noise. This is consistent with the two indexes being about the \\nsame size.\\n\\nThis is on machine with i5-2500k CPU and 8GB of RAM, which is just \\nenough to keep everything in RAM. It seems somewhat strange that your \\nmachine does this in 10ms, i.e. 10x faster. Seems strange.\\n\\n\\nI'm not sure what is the point of the second query, considering it's not \\neven using an index but parallel seqscan.\\n\\n\\nAnyway, this still fails to demonstrate any material difference between \\nthe two indexes, and consequently any potential benefit of the proposed \\nnew index type.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Sat, 30 Oct 2021 01:44:08 +0200\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \">\\n> 4 columns: 106 ms\\n> 6 columns: 109 ms\\n>\\n> So there's like 3% difference between the two cases, and even that might\\n> be just noise. This is consistent with the two indexes being about the\\n> same size.\\n>\\nI also don't think we can get great speedup in the mentioned case, so it is\\nnot urgently needed of course. My point is that it is just nice to have a\\nmulticolumn index constructed on stacked trees constructed on separate\\ncolumns, not on the index tuples as a whole thing. At least there is a\\nbenefit of sparing shared memory if we don't need to cache index tuples of\\nseveral similar indexes, instead caching one \\\"compound index\\\". So if\\nsomeone wants to propose this thing I'd support it provided problems with\\nconcurrency, which were mentioned by Peter are solved.\\n\\nThese problems could be appear easy though, as we have index tuples\\nconstructed in a similar way as heap tuples. Maybe it could be easier if we\\nhad another heap am, which stored separate attributes (if so it could be\\nuseful as a better JSON storage method than we have today).\\n\\n--\\nBest regards,\\nPavel Borisov\\n\\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\\n\\n 4 columns: 106 ms\\n 6 columns: 109 ms\\n\\nSo there's like 3% difference between the two cases, and even that might \\nbe just noise. This is consistent with the two indexes being about the \\nsame size.I also don't think we can get great speedup in the mentioned case, so it is not urgently needed of course. My point is that it is just nice to have a multicolumn index constructed on stacked trees constructed on separate columns, not on the index tuples as a whole thing. At least there is a benefit of sparing shared memory if we don't need to cache index tuples of several similar indexes, instead caching one \\\"compound index\\\". So if someone wants to propose this thing I'd support it provided problems with concurrency, which were mentioned by Peter are solved. These problems could be appear easy though, as we have index tuples constructed in a similar way as heap tuples. Maybe it could be easier if we had another heap am, which stored separate attributes (if so it could be useful as a better JSON storage method than we have today).--Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com\",\n \"msg_date\": \"Sun, 31 Oct 2021 19:48:34 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 10/31/21 16:48, Pavel Borisov wrote:\\n> 4 columns: 106 ms\\n> 6 columns: 109 ms\\n> \\n> So there's like 3% difference between the two cases, and even that\\n> might\\n> be just noise. This is consistent with the two indexes being about the\\n> same size.\\n> \\n> I also don't think we can get great speedup in the mentioned case, so it \\n> is not urgently needed of course. My point is that it is just nice to \\n> have a multicolumn index constructed on stacked trees constructed on \\n> separate columns, not on the index tuples as a whole thing.\\n\\nWell, I'd say \\\"nice to have\\\" features are pointless unless they actually \\ngive tangible benefits (like speedup) to users. I'd bet no one is going \\nto implement and maintain something unless it has such benefit, because \\nthey have to weight it against other beneficial features.\\n\\nMaybe there are use cases where this would be beneficial, but so far we \\nhaven't seen one. Usually it's the OP who presents such a case, and a \\nplausible way to improve it - but it seems this thread presents a \\nsolution and now we're looking for an issue it might solve.\\n\\n> At least there is a benefit of sparing shared memory if we don't need\\n> to cache index tuples of several similar indexes, instead caching one\\n> \\\"compound index\\\". So if someone wants to propose this thing I'd\\n> support it provided problems with concurrency, which were mentioned\\n> by Peter are solved.\\n> \\n\\nThe problem with this it assumes the new index would use (significantly) \\nless space than three separate indexes. I find that rather unlikely, but \\nmaybe there is a smart way to achieve that (certainly not in detail).\\n\\nI don't want to sound overly pessimistic and if you have an idea how to \\ndo this, I'd like to hear it. But it seems pretty tricky, particularly \\nif we assume the suffix columns are more variable (which limits the \\n\\\"compression\\\" ratio etc.).\\n\\n> These problems could be appear easy though, as we have index tuples \\n> constructed in a similar way as heap tuples. Maybe it could be easier if \\n> we had another heap am, which stored separate attributes (if so it could \\n> be useful as a better JSON storage method than we have today).\\n> \\n\\nIMO this just moved the goalposts somewhere outside the solar system.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Sun, 31 Oct 2021 18:33:54 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"I agree with the above mentioned.\\nThe only concern I have is that we compare little wrong things.\\nFor read we should compare\\n (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\\nyear, issue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag)\\nOR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )\\nBecause our proposed index for reading should be closer to a combination of\\nthose 3 and we have current solutions like index on all or with Include\\nstatement.\\nWe should try to find a gap between these three cases.\\nFor DML queries\\n (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year\\nINCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence) AND\\n(job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )\\nBecause again the proposed index should be just one and cover all 3\\nseparate ones.\\n\\nIf you agree with these cases I will try to find a bigger time frame to\\ncompare these two cases deeper.\\nThe issue is not high prio but I strongly believe it can help and can be\\nnice feature for even more complicated cases.\\n\\nBest regards.\\n\\n\\n\\n\\nвс, 31 окт. 2021 г. в 21:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\\n\\n>\\n>\\n> On 10/31/21 16:48, Pavel Borisov wrote:\\n> > 4 columns: 106 ms\\n> > 6 columns: 109 ms\\n> >\\n> > So there's like 3% difference between the two cases, and even that\\n> > might\\n> > be just noise. This is consistent with the two indexes being about\\n> the\\n> > same size.\\n> >\\n> > I also don't think we can get great speedup in the mentioned case, so it\\n> > is not urgently needed of course. My point is that it is just nice to\\n> > have a multicolumn index constructed on stacked trees constructed on\\n> > separate columns, not on the index tuples as a whole thing.\\n>\\n> Well, I'd say \\\"nice to have\\\" features are pointless unless they actually\\n> give tangible benefits (like speedup) to users. I'd bet no one is going\\n> to implement and maintain something unless it has such benefit, because\\n> they have to weight it against other beneficial features.\\n>\\n> Maybe there are use cases where this would be beneficial, but so far we\\n> haven't seen one. Usually it's the OP who presents such a case, and a\\n> plausible way to improve it - but it seems this thread presents a\\n> solution and now we're looking for an issue it might solve.\\n>\\n> > At least there is a benefit of sparing shared memory if we don't need\\n> > to cache index tuples of several similar indexes, instead caching one\\n> > \\\"compound index\\\". So if someone wants to propose this thing I'd\\n> > support it provided problems with concurrency, which were mentioned\\n> > by Peter are solved.\\n> >\\n>\\n> The problem with this it assumes the new index would use (significantly)\\n> less space than three separate indexes. I find that rather unlikely, but\\n> maybe there is a smart way to achieve that (certainly not in detail).\\n>\\n> I don't want to sound overly pessimistic and if you have an idea how to\\n> do this, I'd like to hear it. But it seems pretty tricky, particularly\\n> if we assume the suffix columns are more variable (which limits the\\n> \\\"compression\\\" ratio etc.).\\n>\\n> > These problems could be appear easy though, as we have index tuples\\n> > constructed in a similar way as heap tuples. Maybe it could be easier if\\n> > we had another heap am, which stored separate attributes (if so it could\\n> > be useful as a better JSON storage method than we have today).\\n> >\\n>\\n> IMO this just moved the goalposts somewhere outside the solar system.\\n>\\n>\\n> regards\\n>\\n> --\\n> Tomas Vondra\\n> EnterpriseDB: http://www.enterprisedb.com\\n> The Enterprise PostgreSQL Company\\n>\\n\\nI agree with the above mentioned. The only concern I have is that we compare little wrong things.For read we should compare (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, \\n\\nissue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )Because our proposed index for reading should be closer to a combination of those 3 and we have current solutions like index on all or with Include statement. We should try to find a gap between these three cases.For DML queries (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )Because again the proposed index should be just one and cover all 3 separate ones. If you agree with these cases I will try to find a bigger time frame to compare these two cases deeper. The issue is not high prio but I strongly believe it can help and can be nice feature for even more complicated cases.Best regards. вс, 31 окт. 2021 г. в 21:33, Tomas Vondra <tomas.vondra@enterprisedb.com>:\\n\\nOn 10/31/21 16:48, Pavel Borisov wrote:\\n> 4 columns: 106 ms\\n> 6 columns: 109 ms\\n> \\n> So there's like 3% difference between the two cases, and even that\\n> might\\n> be just noise. This is consistent with the two indexes being about the\\n> same size.\\n> \\n> I also don't think we can get great speedup in the mentioned case, so it \\n> is not urgently needed of course. My point is that it is just nice to \\n> have a multicolumn index constructed on stacked trees constructed on \\n> separate columns, not on the index tuples as a whole thing.\\n\\nWell, I'd say \\\"nice to have\\\" features are pointless unless they actually \\ngive tangible benefits (like speedup) to users. I'd bet no one is going \\nto implement and maintain something unless it has such benefit, because \\nthey have to weight it against other beneficial features.\\n\\nMaybe there are use cases where this would be beneficial, but so far we \\nhaven't seen one. Usually it's the OP who presents such a case, and a \\nplausible way to improve it - but it seems this thread presents a \\nsolution and now we're looking for an issue it might solve.\\n\\n> At least there is a benefit of sparing shared memory if we don't need\\n> to cache index tuples of several similar indexes, instead caching one\\n> \\\"compound index\\\". So if someone wants to propose this thing I'd\\n> support it provided problems with concurrency, which were mentioned\\n> by Peter are solved.\\n> \\n\\nThe problem with this it assumes the new index would use (significantly) \\nless space than three separate indexes. I find that rather unlikely, but \\nmaybe there is a smart way to achieve that (certainly not in detail).\\n\\nI don't want to sound overly pessimistic and if you have an idea how to \\ndo this, I'd like to hear it. But it seems pretty tricky, particularly \\nif we assume the suffix columns are more variable (which limits the \\n\\\"compression\\\" ratio etc.).\\n\\n> These problems could be appear easy though, as we have index tuples \\n> constructed in a similar way as heap tuples. Maybe it could be easier if \\n> we had another heap am, which stored separate attributes (if so it could \\n> be useful as a better JSON storage method than we have today).\\n> \\n\\nIMO this just moved the goalposts somewhere outside the solar system.\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Mon, 1 Nov 2021 16:24:38 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"On 11/1/21 1:24 PM, Hayk Manukyan wrote:\\n> I agree with the above mentioned. \\n> The only concern I have is that we compare little wrong things.\\n> For read we should compare \\n> (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\\n> year, issue_flag ) VS (job, nlp, year, sequence, Scan_ID, issue_flag)\\n> OR (job, nlp, year INCLUDE(sequence, Scan_ID, issue_flag) )\\n> Because our proposed index for reading should be closer to a combination\\n> of those 3 and we have current solutions like index on all or with\\n> Include statement. \\n\\nI don't follow.\\n\\nThe whole point of the experiment was to show the gap between a \\\"best\\ncase\\\" and \\\"worst case\\\" alternatives, with the assumption the gap would\\nbe substantial and the new index type might get close to the best case.\\n\\nAre you suggesting those are not the actual best/worst cases and we\\nshould use some other indexes? If yes, which ones?\\n\\n\\nIMHO those best/worst cases are fine because:\\n\\n1) best case (job, nlp, year, sequence)\\n\\nI don't see how we could get anything better for queries on \\\"sequence\\\"\\nthan this index, because that's literally one of the indexes that would\\nbe included in the whole index.\\n\\nYes, if you need to support queries on additional columns, you might\\nneed more indexes, but that's irrelevant - why would anyone define those\\nindexes, when the \\\"worst case\\\" btree index with all the columns is so\\nclose to the best case?\\n\\n\\n2) worst case (job, nlp, year, scan_id, issue_flag, sequence)\\n\\nI think an index with INCLUDE is entirely irrelevant here. The reason to\\nuse INCLUDE is to define UNIQUE index on a subset of columns, but that's\\nnot what we need here. I repeated the benchmark with such index, and the\\ntiming is ~150ms, so about 50% slower than the simple index. Sorting on\\nall columns is clearly beneficial even for the last column.\\n\\n\\nSo I still think those best/worst cases are sensible, and the proposed\\nindex would need to beat the worst case. Which seems challenging,\\nconsidering how close it is to the best case. Or it might break the best\\ncase, if there's some sort of revolutionary way to store the small\\nindexes or something like that.\\n\\nThe fact that there's no size difference between the two cases is mostly\\na coincidence, due to the columns being just 2B each, and with wider\\nvalues the difference might be substantial, making the gap larger. But\\nthen the new index would have to improve on this, but there's no\\nproposal on how to do that.\\n\\n\\n> We should try to find a gap between these three cases.\\n> For DML queries \\n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year\\n> INCLUDE(sequence, Scan_ID, issue_flag) ) VS (job, nlp, year, sequence)\\n> AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag )\\n> Because again the proposed index should be just one and cover all 3\\n> separate ones. \\n> \\n> If you agree with these cases I will try to find a bigger time frame to\\n> compare these two cases deeper. \\n>\\n> The issue is not high prio but I strongly believe it can help and can be\\n> nice feature for even more complicated cases.\\n> \\n\\nYou don't need my approval to run benchmarks etc. If you believe this is\\nbeneficial then just do the tests and you'll see if it makes sense ...\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 16:03:08 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\\n<tomas.vondra@enterprisedb.com> wrote:\\n> If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n> then for each subset you want a separate \\\"small\\\" trees on each of the\\n> other columns, so in this case three trees.\\n>\\n> Well, the problem with this is pretty obvious - each of the small trees\\n> requires separate copies of the leaf pages. And remember, in a btree the\\n> internal pages are usually less than 1% of the index, so this pretty\\n> much triples the size of the index. And if you insert a row into the\\n> index, it has to insert the item pointer into each of the small trees,\\n> likely requiring a separate I/O for each.\\n>\\n> So I'd bet this is not any different from just having three separate\\n> indexes - it doesn't save space, doesn't save I/O, nothing.\\n\\nI agree. In a lot of cases, it's actually useful to define the index\\non fewer columns, like (job, nlp, year) or even just (job, nlp) or\\neven just (job) because it makes the index so much smaller and that's\\npretty important. If you have enough duplicate entries in a (job, nlp,\\nyear) index to justify create a (job, nlp, year, sequence) index, the\\nnumber of distinct (job, nlp, year) tuples has to be small compared to\\nthe number of (job, nlp, year, sequence) tuples - and that means that\\nyou wouldn't actually save much by combining your (job, nlp, year,\\nsequence) index with a (job, nlp, year, other-stuff) index. As you\\nsay, the internal pages aren't the problem.\\n\\nI don't intend to say that there's no possible use for this kind of\\ntechnology. Peter G. says that people are writing research papers\\nabout that and they probably wouldn't be doing that unless they'd\\nfound some case where it's a big win. But this example seems extremely\\nunconvincing.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 16:06:15 -0400\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 11/1/21 21:06, Robert Haas wrote:\\n> On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\\n> <tomas.vondra@enterprisedb.com> wrote:\\n>> If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n>> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n>> then for each subset you want a separate \\\"small\\\" trees on each of the\\n>> other columns, so in this case three trees.\\n>>\\n>> Well, the problem with this is pretty obvious - each of the small trees\\n>> requires separate copies of the leaf pages. And remember, in a btree the\\n>> internal pages are usually less than 1% of the index, so this pretty\\n>> much triples the size of the index. And if you insert a row into the\\n>> index, it has to insert the item pointer into each of the small trees,\\n>> likely requiring a separate I/O for each.\\n>>\\n>> So I'd bet this is not any different from just having three separate\\n>> indexes - it doesn't save space, doesn't save I/O, nothing.\\n> \\n> I agree. In a lot of cases, it's actually useful to define the index\\n> on fewer columns, like (job, nlp, year) or even just (job, nlp) or\\n> even just (job) because it makes the index so much smaller and that's\\n> pretty important. If you have enough duplicate entries in a (job, nlp,\\n> year) index to justify create a (job, nlp, year, sequence) index, the\\n> number of distinct (job, nlp, year) tuples has to be small compared to\\n> the number of (job, nlp, year, sequence) tuples - and that means that\\n> you wouldn't actually save much by combining your (job, nlp, year,\\n> sequence) index with a (job, nlp, year, other-stuff) index. As you\\n> say, the internal pages aren't the problem.\\n> \\n> I don't intend to say that there's no possible use for this kind of\\n> technology. Peter G. says that people are writing research papers\\n> about that and they probably wouldn't be doing that unless they'd\\n> found some case where it's a big win. But this example seems extremely\\n> unconvincing.\\n> \\n\\nI actually looked at the use case mentioned by Peter G, i.e. merged \\nindexes with master-detail clustering (see e.g. [1]), but that seems \\nlike a rather different thing. The master-detail refers to storing rows \\nfrom multiple tables, interleaved in a way that allows faster joins. So \\nit's essentially a denormalization tool.\\n\\nPerhaps there's something we could learn about efficient storage of the \\nsmall trees, but I haven't found any papers describing that (I haven't \\nspent much time on the search, though).\\n\\n[1] Algorithms for merged indexes, Goetz Graefe\\n https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Mon, 1 Nov 2021 22:15:59 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"Tomas Vondra\\n> Are you suggesting those are not the actual best/worst cases and we\\n> should use some other indexes? If yes, which ones?\\n\\nI would say yes.\\nIn my case I am not querying only sequence column.\\nI have the following cases which I want to optimize.\\n1. Select * from Some_table where job = <somthing> and nlp = <something>\\nand year = <something> and *scan_id = <something> *\\n2. Select * from Some_table where job = <somthing> and nlp = <something>\\nand year = <something> and *Issue_flag = <something> *\\n3. Select * from Some_table where job = <somthing> and nlp = <something>\\nand year = <something> and *sequence = <something> *\\nThose are queries that my app send to db that is why I said that from *read\\nperspective* our *best case* is 3 separate indexes for\\n *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\\nnlp, year, issue_flag)* and any other solution like\\n (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\\nINCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\\nconsidered as* worst case *\\nI will remind that in real world scenario I have ~50m rows and about *~5k\\nrows for each (job, nlp, year )*\\n From *write perspective* as far as we want to have only one index our* best\\ncase* can be considered any of\\n*(job, nlp, year, sequence, Scan_ID, issue_flag)* OR * (job, nlp, year )\\nINCLUDE(sequence, Scan_ID, issue_flag) *\\nand the* worst case* will be having 3 separate queries like in read\\nperspective\\n(job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp,\\nyear, issue_flag)\\n\\nSo I think the comparison that we did is not right because we are comparing\\ndifferent/wrong things.\\n\\nFor right results we need to compare this two cases when we are doing\\nrandom queries with 1,2,3 and random writes.\\n\\n\\nвт, 2 нояб. 2021 г. в 01:16, Tomas Vondra <tomas.vondra@enterprisedb.com>:\\n\\n>\\n>\\n> On 11/1/21 21:06, Robert Haas wrote:\\n> > On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\\n> > <tomas.vondra@enterprisedb.com> wrote:\\n> >> If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n> >> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n> >> then for each subset you want a separate \\\"small\\\" trees on each of the\\n> >> other columns, so in this case three trees.\\n> >>\\n> >> Well, the problem with this is pretty obvious - each of the small trees\\n> >> requires separate copies of the leaf pages. And remember, in a btree the\\n> >> internal pages are usually less than 1% of the index, so this pretty\\n> >> much triples the size of the index. And if you insert a row into the\\n> >> index, it has to insert the item pointer into each of the small trees,\\n> >> likely requiring a separate I/O for each.\\n> >>\\n> >> So I'd bet this is not any different from just having three separate\\n> >> indexes - it doesn't save space, doesn't save I/O, nothing.\\n> >\\n> > I agree. In a lot of cases, it's actually useful to define the index\\n> > on fewer columns, like (job, nlp, year) or even just (job, nlp) or\\n> > even just (job) because it makes the index so much smaller and that's\\n> > pretty important. If you have enough duplicate entries in a (job, nlp,\\n> > year) index to justify create a (job, nlp, year, sequence) index, the\\n> > number of distinct (job, nlp, year) tuples has to be small compared to\\n> > the number of (job, nlp, year, sequence) tuples - and that means that\\n> > you wouldn't actually save much by combining your (job, nlp, year,\\n> > sequence) index with a (job, nlp, year, other-stuff) index. As you\\n> > say, the internal pages aren't the problem.\\n> >\\n> > I don't intend to say that there's no possible use for this kind of\\n> > technology. Peter G. says that people are writing research papers\\n> > about that and they probably wouldn't be doing that unless they'd\\n> > found some case where it's a big win. But this example seems extremely\\n> > unconvincing.\\n> >\\n>\\n> I actually looked at the use case mentioned by Peter G, i.e. merged\\n> indexes with master-detail clustering (see e.g. [1]), but that seems\\n> like a rather different thing. The master-detail refers to storing rows\\n> from multiple tables, interleaved in a way that allows faster joins. So\\n> it's essentially a denormalization tool.\\n>\\n> Perhaps there's something we could learn about efficient storage of the\\n> small trees, but I haven't found any papers describing that (I haven't\\n> spent much time on the search, though).\\n>\\n> [1] Algorithms for merged indexes, Goetz Graefe\\n> https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\\n>\\n>\\n> regards\\n>\\n> --\\n> Tomas Vondra\\n> EnterpriseDB: http://www.enterprisedb.com\\n> The Enterprise PostgreSQL Company\\n>\\n\\nTomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year )From write perspective as far as we want to have only one index our best case can be considered any of(job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) and the worst case will be having 3 separate queries like in read perspective (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) So I think the comparison that we did is not right because we are comparing different/wrong things.For right results we need to compare this two cases when we are doing random queries with 1,2,3 and random writes.вт, 2 нояб. 2021 г. в 01:16, Tomas Vondra <tomas.vondra@enterprisedb.com>:\\n\\nOn 11/1/21 21:06, Robert Haas wrote:\\n> On Tue, Oct 26, 2021 at 11:11 AM Tomas Vondra\\n> <tomas.vondra@enterprisedb.com> wrote:\\n>> If I get what you propose, you want to have a \\\"top\\\" tree for (job, nlp,\\n>> year), which \\\"splits\\\" the data set into subsets of ~5000-7000 rows. And\\n>> then for each subset you want a separate \\\"small\\\" trees on each of the\\n>> other columns, so in this case three trees.\\n>>\\n>> Well, the problem with this is pretty obvious - each of the small trees\\n>> requires separate copies of the leaf pages. And remember, in a btree the\\n>> internal pages are usually less than 1% of the index, so this pretty\\n>> much triples the size of the index. And if you insert a row into the\\n>> index, it has to insert the item pointer into each of the small trees,\\n>> likely requiring a separate I/O for each.\\n>>\\n>> So I'd bet this is not any different from just having three separate\\n>> indexes - it doesn't save space, doesn't save I/O, nothing.\\n> \\n> I agree. In a lot of cases, it's actually useful to define the index\\n> on fewer columns, like (job, nlp, year) or even just (job, nlp) or\\n> even just (job) because it makes the index so much smaller and that's\\n> pretty important. If you have enough duplicate entries in a (job, nlp,\\n> year) index to justify create a (job, nlp, year, sequence) index, the\\n> number of distinct (job, nlp, year) tuples has to be small compared to\\n> the number of (job, nlp, year, sequence) tuples - and that means that\\n> you wouldn't actually save much by combining your (job, nlp, year,\\n> sequence) index with a (job, nlp, year, other-stuff) index. As you\\n> say, the internal pages aren't the problem.\\n> \\n> I don't intend to say that there's no possible use for this kind of\\n> technology. Peter G. says that people are writing research papers\\n> about that and they probably wouldn't be doing that unless they'd\\n> found some case where it's a big win. But this example seems extremely\\n> unconvincing.\\n> \\n\\nI actually looked at the use case mentioned by Peter G, i.e. merged \\nindexes with master-detail clustering (see e.g. [1]), but that seems \\nlike a rather different thing. The master-detail refers to storing rows \\nfrom multiple tables, interleaved in a way that allows faster joins. So \\nit's essentially a denormalization tool.\\n\\nPerhaps there's something we could learn about efficient storage of the \\nsmall trees, but I haven't found any papers describing that (I haven't \\nspent much time on the search, though).\\n\\n[1] Algorithms for merged indexes, Goetz Graefe\\n https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.140.7709\\n\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\",\n \"msg_date\": \"Tue, 2 Nov 2021 16:04:29 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"\\n\\nOn 11/2/21 13:04, Hayk Manukyan wrote:\\n> Tomas Vondra\\n> > Are you suggesting those are not the actual best/worst cases and we\\n> > should use some other indexes? If yes, which ones?\\n> \\n> I would say yes.\\n> In my case I am not querying only sequence column.\\n> I have the following cases which I want to optimize.\\n> 1. Select * from Some_table where job = <somthing> and nlp = <something> \\n> and year = <something> and *scan_id = <something> *\\n> 2. Select * from Some_table where job = <somthing> and nlp = <something> \\n> and year = <something> and *Issue_flag = <something> *\\n> 3. Select * from Some_table where job = <somthing> and nlp = <something> \\n> and year = <something> and *sequence = <something> *\\n> Those are queries that my app send to db that is why I said that from \\n> *read perspective* our *best case* is 3 separate indexes for\\n> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job, \\n> nlp, year, issue_flag)* and any other solution like\\n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) \\n> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be \\n> considered as*worst case *\\n\\nI already explained why using INCLUDE in this case is the wrong thing to \\ndo, it'll harm performance compared to just defining a regular index.\\n\\n> I will remind that in real world scenario I have ~50m rows and about \\n> *~5k rows for each (job, nlp, year )*\\n\\nWell, maybe this is the problem. We have 50M rows, but the three columns \\nhave too many distinct values - (job, nlp, year) defines ~50M groups, so \\nthere's only a single row per group. That'd explain why the two indexes \\nperform almost equally.\\n\\nSo I guess you need to modify the data generator so that the data set is \\nmore like the case you're trying to improve.\\n\\n> From *write perspective* as far as we want to have only one index \\n> our*best case* can be considered any of\\n> *(job, nlp, year, sequence, Scan_ID, issue_flag)* OR *(job, nlp, year ) \\n> INCLUDE(sequence, Scan_ID, issue_flag) *\\n> and the*worst case* will be having 3 separate queries like in read \\n> perspective\\n> (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, \\n> year, issue_flag)\\n> \\n\\nMaybe. It's true a write with three indexes will require modification to \\nthree leaf pages (on average). With a single index we have to modify \\njust one leaf page, depending on where the row gets routed.\\n\\nBut with the proposed \\\"merged\\\" index, the row will have to be inserted \\ninto three smaller trees. If the trees are large enough, they won't fit \\ninto a single leaf page (e.g. the 5000 index tuples is guaranteed to \\nneed many pages, even if you use some smart encoding). So the write will \\nlikely need to modify at least 3 leaf pages, getting much closer to \\nthree separate indexes. At which point you could just use three indexes.\\n\\n> So I think the comparison that we did is not right because we are \\n> comparing different/wrong things.\\n> > For right results we need to compare this two cases when we are doing\\n> random queries with 1,2,3 and random writes.\\n> \\n\\nI'm not going to spend any more time on tweaking the benchmark, but if \\nyou tweak it to demonstrate the difference / benefits I'll run it again \\non my machine etc.\\n\\nregards\\n\\n-- \\nTomas Vondra\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\",\n \"msg_date\": \"Tue, 2 Nov 2021 15:03:06 +0100\",\n \"msg_from\": \"Tomas Vondra <tomas.vondra@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:\\n\\n> Tomas Vondra\\n> > Are you suggesting those are not the actual best/worst cases and we\\n> > should use some other indexes? If yes, which ones?\\n>\\n> I would say yes.\\n> In my case I am not querying only sequence column.\\n> I have the following cases which I want to optimize.\\n> 1. Select * from Some_table where job = <somthing> and nlp = <something>\\n> and year = <something> and *scan_id = <something> *\\n> 2. Select * from Some_table where job = <somthing> and nlp = <something>\\n> and year = <something> and *Issue_flag = <something> *\\n> 3. Select * from Some_table where job = <somthing> and nlp = <something>\\n> and year = <something> and *sequence = <something> *\\n> Those are queries that my app send to db that is why I said that from *read\\n> perspective* our *best case* is 3 separate indexes for\\n> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\\n> nlp, year, issue_flag)* and any other solution like\\n> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\\n> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\\n> considered as* worst case *\\n> I will remind that in real world scenario I have ~50m rows and about *~5k\\n> rows for each (job, nlp, year )*\\n>\\n\\n So you get 50M rows /5K rows = 10K times selectivity, when you select on\\njob = <somthing> and nlp = <something> and year = <something> which is\\nenormous. Then you should select some of the 5K rows left, which is\\nexpected to be pretty fast on bitmap index scan or INCLUDE column\\nfiltering. It confirms Tomas's experiment\\n\\n pgbench -n -f q4.sql -T 60\\n\\n106 ms vs 109 ms\\n\\nfits your case pretty well. You get absolutely negligible difference\\nbetween best and worst case and certainly you don't need anything more than\\njust plain index for 3 columns, you even don't need INCLUDE index.\\n\\n From what I read I suppose that this feature indeed doesn't based on the\\nreal need. If you suppose it is useful please feel free to make and post\\nhere some measurements that proves your point.\\n\\n\\n\\n\\n-- \\nBest regards,\\nPavel Borisov\\n\\nPostgres Professional: http://postgrespro.com <http://www.postgrespro.com>\\n\\nвт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:Tomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year ) So you get 50M rows /5K rows = 10K times selectivity, when you select on job = <somthing> and nlp = <something> and year = <something> which is enormous. Then you should select some of the 5K rows left, which is expected to be pretty fast on bitmap index scan or INCLUDE column filtering. It confirms Tomas's experiment pgbench -n -f q4.sql -T 60106 ms vs 109 msfits your case pretty well. You get absolutely negligible difference between best and worst case and certainly you don't need anything more than just plain index for 3 columns, you even don't need INCLUDE index.From what I read I suppose that this feature indeed doesn't based on the real need. If you suppose it is useful please feel free to make and post here some measurements that proves your point.-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com\",\n \"msg_date\": \"Tue, 2 Nov 2021 18:04:14 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n },\n {\n \"msg_contents\": \"Hi All\\n\\nI did final research and saw that the difference between best and worst\\ncases is indeed really small.\\nI want to thank you guys for your time and efforts.\\n\\nBest regards.\\n\\n\\nвт, 2 нояб. 2021 г. в 18:04, Pavel Borisov <pashkin.elfe@gmail.com>:\\n\\n> вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:\\n>\\n>> Tomas Vondra\\n>> > Are you suggesting those are not the actual best/worst cases and we\\n>> > should use some other indexes? If yes, which ones?\\n>>\\n>> I would say yes.\\n>> In my case I am not querying only sequence column.\\n>> I have the following cases which I want to optimize.\\n>> 1. Select * from Some_table where job = <somthing> and nlp = <something>\\n>> and year = <something> and *scan_id = <something> *\\n>> 2. Select * from Some_table where job = <somthing> and nlp = <something>\\n>> and year = <something> and *Issue_flag = <something> *\\n>> 3. Select * from Some_table where job = <somthing> and nlp = <something>\\n>> and year = <something> and *sequence = <something> *\\n>> Those are queries that my app send to db that is why I said that from *read\\n>> perspective* our *best case* is 3 separate indexes for\\n>> *(job, nlp, year, sequence)* AND *(job, nlp, year, Scan_ID)* and *(job,\\n>> nlp, year, issue_flag)* and any other solution like\\n>> (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year )\\n>> INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be\\n>> considered as* worst case *\\n>> I will remind that in real world scenario I have ~50m rows and about *~5k\\n>> rows for each (job, nlp, year )*\\n>>\\n>\\n> So you get 50M rows /5K rows = 10K times selectivity, when you select on\\n> job = <somthing> and nlp = <something> and year = <something> which is\\n> enormous. Then you should select some of the 5K rows left, which is\\n> expected to be pretty fast on bitmap index scan or INCLUDE column\\n> filtering. It confirms Tomas's experiment\\n>\\n> pgbench -n -f q4.sql -T 60\\n>\\n> 106 ms vs 109 ms\\n>\\n> fits your case pretty well. You get absolutely negligible difference\\n> between best and worst case and certainly you don't need anything more than\\n> just plain index for 3 columns, you even don't need INCLUDE index.\\n>\\n> From what I read I suppose that this feature indeed doesn't based on the\\n> real need. If you suppose it is useful please feel free to make and post\\n> here some measurements that proves your point.\\n>\\n>\\n>\\n>\\n> --\\n> Best regards,\\n> Pavel Borisov\\n>\\n> Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>\\n>\\n\\nHi AllI did final research and saw that the difference between best and worst cases is indeed really small.I want to thank you guys for your time and efforts.Best regards.вт, 2 нояб. 2021 г. в 18:04, Pavel Borisov <pashkin.elfe@gmail.com>:вт, 2 нояб. 2021 г. в 16:04, Hayk Manukyan <manukyantt@gmail.com>:Tomas Vondra> Are you suggesting those are not the actual best/worst cases and we> should use some other indexes? If yes, which ones?I would say yes.In my case I am not querying only sequence column.I have the following cases which I want to optimize.1. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and scan_id = <something> 2. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and Issue_flag = <something> 3. Select * from Some_table where job = <somthing> and nlp = <something> and year = <something> and sequence = <something> Those are queries that my app send to db that is why I said that from read perspective our best case is 3 separate indexes for (job, nlp, year, sequence) AND (job, nlp, year, Scan_ID) and (job, nlp, year, issue_flag) and any other solution like (job, nlp, year, sequence, Scan_ID, issue_flag) OR (job, nlp, year ) INCLUDE(sequence, Scan_ID, issue_flag) OR just (job, nlp, year) can be considered as worst case I will remind that in real world scenario I have ~50m rows and about ~5k rows for each (job, nlp, year ) So you get 50M rows /5K rows = 10K times selectivity, when you select on job = <somthing> and nlp = <something> and year = <something> which is enormous. Then you should select some of the 5K rows left, which is expected to be pretty fast on bitmap index scan or INCLUDE column filtering. It confirms Tomas's experiment pgbench -n -f q4.sql -T 60106 ms vs 109 msfits your case pretty well. You get absolutely negligible difference between best and worst case and certainly you don't need anything more than just plain index for 3 columns, you even don't need INCLUDE index.From what I read I suppose that this feature indeed doesn't based on the real need. If you suppose it is useful please feel free to make and post here some measurements that proves your point.-- Best regards,Pavel BorisovPostgres Professional: http://postgrespro.com\",\n \"msg_date\": \"Fri, 5 Nov 2021 15:17:49 +0400\",\n \"msg_from\": \"Hayk Manukyan <manukyantt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Feature request for adoptive indexes\"\n }\n]","isConversational":false}}},{"rowIdx":52991,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hello.\n\nI noticed that the following command doesn't leave connection log in\nlog file.\n\n> psql \"host=localhost options=-c\\ log_connections=on\"\n\nThe reason is we log connections before the options is processed. We\nneed to move the code from BackendInitialize to InitPostgres where\nthat options are processed if we want that option to work. However,\nI'm not sure we can delay connection-log until that point, since that\nmovement changes the meaning of the log message.\n\nAnother option is to log connections in InitPostgres if not yet and\nlog_connections is turned on by connection options.\n\nFuther another option is we don't make it work and write in the\ndocument that it doesn't work. (I didn't find that, but...)\n\n\nOpinions and suggestions are welcome.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Tue, 26 Oct 2021 17:33:50 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":true,"msg_subject":"Setting log_connection in connection string doesn't work"},{"msg_contents":"Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:\n> I noticed that the following command doesn't leave connection log in\n> log file.\n>> psql \"host=localhost options=-c\\ log_connections=on\"\n\n[ shrug... ] Why would you expect it to? Should \"-c log_connections=off\"\nbe able to hide a connection from the log?\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 09:39:12 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"At Tue, 26 Oct 2021 09:39:12 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote in \n> Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:\n> > I noticed that the following command doesn't leave connection log in\n> > log file.\n> >> psql \"host=localhost options=-c\\ log_connections=on\"\n> \n> [ shrug... ] Why would you expect it to? Should \"-c log_connections=off\"\n> be able to hide a connection from the log?\n\nI don't know. The fact is that it's a superuser-backend variable that\nis silently ignored (but acutally seems to be set in the session).\nSetting log_disconnection the same way works (of course the impliction\nof this is far less significant that the log_connection case).\n\nIf we want to refuse them to be set at session start (and I think so),\nshouldn't they be changed to SIGHUP? (I forgot to mention this choice\nin the previous mail..)\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center","msg_date":"Wed, 27 Oct 2021 10:24:05 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\n> I don't know. The fact is that it's a superuser-backend variable that\n> is silently ignored (but acutally seems to be set in the session).\n> Setting log_disconnection the same way works (of course the impliction\n> of this is far less significant that the log_connection case).\n\nfe550b2 is the commit that has changed both those parameters to be\nPGC_SU_BACKEND, with the commit log mentioning the case you are\ndescribing. That would be the area of this thread:\nhttps://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\n\nAs Tom and this thread are saying, there may be a use-case for\nmaking log_connections more effective at startup so as superusers\ncould hide their logs at will. However, honestly, I am not sure that\nthis is worth spending time improving this as the use-case looks\nrather thin to me. Perhaps you are right and we could just mark both\nof those GUCs as PGC_SIGHUP, making the whole easier to understand and\nmore consistent, though. If we do that, the patch is wrong, as the\ndocs would also need a refresh.\n--\nMichael","msg_date":"Wed, 27 Oct 2021 10:55:31 +0900","msg_from":"Michael Paquier <michael@paquier.xyz>","msg_from_op":false,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"At Wed, 27 Oct 2021 10:55:31 +0900, Michael Paquier <michael@paquier.xyz> wrote in \n> On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\n> > I don't know. The fact is that it's a superuser-backend variable that\n> > is silently ignored (but acutally seems to be set in the session).\n> > Setting log_disconnection the same way works (of course the impliction\n> > of this is far less significant that the log_connection case).\n> \n> fe550b2 is the commit that has changed both those parameters to be\n> PGC_SU_BACKEND, with the commit log mentioning the case you are\n> describing. That would be the area of this thread:\n> https://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\n\nThanks for the pointer. (I didn't remember of that thread..)\n\n> As Tom and this thread are saying, there may be a use-case for\n> making log_connections more effective at startup so as superusers\n> could hide their logs at will. However, honestly, I am not sure that\n> this is worth spending time improving this as the use-case looks\n> rather thin to me. Perhaps you are right and we could just mark both\n\nI tend to agree.\n\n> of those GUCs as PGC_SIGHUP, making the whole easier to understand and\n> more consistent, though. If we do that, the patch is wrong, as the\n> docs would also need a refresh.\n\nYeah, this is the full version of the patch.\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center","msg_date":"Wed, 27 Oct 2021 11:53:09 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":true,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"\nThis patch is from October of 2021. I don't see any commitfest entry\nfor it. Should it be applied?\n\n---------------------------------------------------------------------------\n\nOn Wed, Oct 27, 2021 at 11:53:09AM +0900, Kyotaro Horiguchi wrote:\n> At Wed, 27 Oct 2021 10:55:31 +0900, Michael Paquier <michael@paquier.xyz> wrote in \n> > On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\n> > > I don't know. The fact is that it's a superuser-backend variable that\n> > > is silently ignored (but acutally seems to be set in the session).\n> > > Setting log_disconnection the same way works (of course the impliction\n> > > of this is far less significant that the log_connection case).\n> > \n> > fe550b2 is the commit that has changed both those parameters to be\n> > PGC_SU_BACKEND, with the commit log mentioning the case you are\n> > describing. That would be the area of this thread:\n> > https://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\n> \n> Thanks for the pointer. (I didn't remember of that thread..)\n> \n> > As Tom and this thread are saying, there may be a use-case for\n> > making log_connections more effective at startup so as superusers\n> > could hide their logs at will. However, honestly, I am not sure that\n> > this is worth spending time improving this as the use-case looks\n> > rather thin to me. Perhaps you are right and we could just mark both\n> \n> I tend to agree.\n> \n> > of those GUCs as PGC_SIGHUP, making the whole easier to understand and\n> > more consistent, though. If we do that, the patch is wrong, as the\n> > docs would also need a refresh.\n> \n> Yeah, this is the full version of the patch.\n> \n> regards.\n> \n> -- \n> Kyotaro Horiguchi\n> NTT Open Source Software Center\n\n> >From 11a9612c2590f57f431c3918d5b62c08a5b29efb Mon Sep 17 00:00:00 2001\n> From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>\n> Date: Wed, 27 Oct 2021 11:39:02 +0900\n> Subject: [PATCH] Change log_(dis)connections to PGC_SIGHUP\n> \n> log_connections is not effective when it is given in connection\n> options. Since no complaint has been heard for this behavior the\n> use-case looks rather thin. Thus we change it to PGC_SIGHUP, rahther\n> than putting efforts to make it effective for the\n> use-case. log_disconnections is working with the usage but be\n> consistent by treating it the same way with log_connection.\n> ---\n> doc/src/sgml/config.sgml | 8 ++++----\n> src/backend/utils/misc/guc.c | 4 ++--\n> 2 files changed, 6 insertions(+), 6 deletions(-)\n> \n> diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml\n> index de77f14573..64b04a47d2 100644\n> --- a/doc/src/sgml/config.sgml\n> +++ b/doc/src/sgml/config.sgml\n> @@ -6800,8 +6800,8 @@ local0.* /var/log/postgresql\n> Causes each attempted connection to the server to be logged,\n> as well as successful completion of both client authentication (if\n> necessary) and authorization.\n> - Only superusers can change this parameter at session start,\n> - and it cannot be changed at all within a session.\n> + This parameter can only be set in the <filename>postgresql.conf</filename>\n> + file or on the server command line.\n> The default is <literal>off</literal>.\n> </para>\n> \n> @@ -6827,8 +6827,8 @@ local0.* /var/log/postgresql\n> Causes session terminations to be logged. The log output\n> provides information similar to <varname>log_connections</varname>,\n> plus the duration of the session.\n> - Only superusers can change this parameter at session start,\n> - and it cannot be changed at all within a session.\n> + This parameter can only be set in the <filename>postgresql.conf</filename>\n> + file or on the server command line.\n> The default is <literal>off</literal>.\n> </para>\n> </listitem>\n> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c\n> index e91d5a3cfd..57d810c80d 100644\n> --- a/src/backend/utils/misc/guc.c\n> +++ b/src/backend/utils/misc/guc.c\n> @@ -1353,7 +1353,7 @@ static struct config_bool ConfigureNamesBool[] =\n> \t\tNULL, NULL, NULL\n> \t},\n> \t{\n> -\t\t{\"log_connections\", PGC_SU_BACKEND, LOGGING_WHAT,\n> +\t\t{\"log_connections\", PGC_SIGHUP, LOGGING_WHAT,\n> \t\t\tgettext_noop(\"Logs each successful connection.\"),\n> \t\t\tNULL\n> \t\t},\n> @@ -1362,7 +1362,7 @@ static struct config_bool ConfigureNamesBool[] =\n> \t\tNULL, NULL, NULL\n> \t},\n> \t{\n> -\t\t{\"log_disconnections\", PGC_SU_BACKEND, LOGGING_WHAT,\n> +\t\t{\"log_disconnections\", PGC_SIGHUP, LOGGING_WHAT,\n> \t\t\tgettext_noop(\"Logs end of a session, including duration.\"),\n> \t\t\tNULL\n> \t\t},\n> -- \n> 2.27.0\n> \n\n\n-- \n Bruce Momjian <bruce@momjian.us> https://momjian.us\n EDB https://enterprisedb.com\n\n Indecision is a decision. Inaction is an action. Mark Batterson\n\n\n\n","msg_date":"Wed, 17 Aug 2022 10:23:06 -0400","msg_from":"Bruce Momjian <bruce@momjian.us>","msg_from_op":false,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"Bruce Momjian <bruce@momjian.us> writes:\n> This patch is from October of 2021. I don't see any commitfest entry\n> for it. Should it be applied?\n\nI think we decided not to. The original argument for having these\nbe PGC_SU_BACKEND was to try to ensure that you got matching\nconnection and disconnection log entries for any one session,\nand I don't see anything that supersedes that plan.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 17 Aug 2022 10:29:26 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Setting log_connection in connection string doesn't work"},{"msg_contents":"On Wed, Aug 17, 2022 at 10:29:26AM -0400, Tom Lane wrote:\n> Bruce Momjian <bruce@momjian.us> writes:\n> > This patch is from October of 2021. I don't see any commitfest entry\n> > for it. Should it be applied?\n> \n> I think we decided not to. The original argument for having these\n> be PGC_SU_BACKEND was to try to ensure that you got matching\n> connection and disconnection log entries for any one session,\n> and I don't see anything that supersedes that plan.\n\nOkay, thanks for the feedback.\n\n-- \n Bruce Momjian <bruce@momjian.us> https://momjian.us\n EDB https://enterprisedb.com\n\n Indecision is a decision. Inaction is an action. Mark Batterson\n\n\n\n","msg_date":"Wed, 17 Aug 2022 10:30:16 -0400","msg_from":"Bruce Momjian <bruce@momjian.us>","msg_from_op":false,"msg_subject":"Re: Setting log_connection in connection string doesn't work"}],"string":"[\n {\n \"msg_contents\": \"Hello.\\n\\nI noticed that the following command doesn't leave connection log in\\nlog file.\\n\\n> psql \\\"host=localhost options=-c\\\\ log_connections=on\\\"\\n\\nThe reason is we log connections before the options is processed. We\\nneed to move the code from BackendInitialize to InitPostgres where\\nthat options are processed if we want that option to work. However,\\nI'm not sure we can delay connection-log until that point, since that\\nmovement changes the meaning of the log message.\\n\\nAnother option is to log connections in InitPostgres if not yet and\\nlog_connections is turned on by connection options.\\n\\nFuther another option is we don't make it work and write in the\\ndocument that it doesn't work. (I didn't find that, but...)\\n\\n\\nOpinions and suggestions are welcome.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 17:33:50 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:\\n> I noticed that the following command doesn't leave connection log in\\n> log file.\\n>> psql \\\"host=localhost options=-c\\\\ log_connections=on\\\"\\n\\n[ shrug... ] Why would you expect it to? Should \\\"-c log_connections=off\\\"\\nbe able to hide a connection from the log?\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 09:39:12 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"At Tue, 26 Oct 2021 09:39:12 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote in \\n> Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:\\n> > I noticed that the following command doesn't leave connection log in\\n> > log file.\\n> >> psql \\\"host=localhost options=-c\\\\ log_connections=on\\\"\\n> \\n> [ shrug... ] Why would you expect it to? Should \\\"-c log_connections=off\\\"\\n> be able to hide a connection from the log?\\n\\nI don't know. The fact is that it's a superuser-backend variable that\\nis silently ignored (but acutally seems to be set in the session).\\nSetting log_disconnection the same way works (of course the impliction\\nof this is far less significant that the log_connection case).\\n\\nIf we want to refuse them to be set at session start (and I think so),\\nshouldn't they be changed to SIGHUP? (I forgot to mention this choice\\nin the previous mail..)\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\",\n \"msg_date\": \"Wed, 27 Oct 2021 10:24:05 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\\n> I don't know. The fact is that it's a superuser-backend variable that\\n> is silently ignored (but acutally seems to be set in the session).\\n> Setting log_disconnection the same way works (of course the impliction\\n> of this is far less significant that the log_connection case).\\n\\nfe550b2 is the commit that has changed both those parameters to be\\nPGC_SU_BACKEND, with the commit log mentioning the case you are\\ndescribing. That would be the area of this thread:\\nhttps://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\\n\\nAs Tom and this thread are saying, there may be a use-case for\\nmaking log_connections more effective at startup so as superusers\\ncould hide their logs at will. However, honestly, I am not sure that\\nthis is worth spending time improving this as the use-case looks\\nrather thin to me. Perhaps you are right and we could just mark both\\nof those GUCs as PGC_SIGHUP, making the whole easier to understand and\\nmore consistent, though. If we do that, the patch is wrong, as the\\ndocs would also need a refresh.\\n--\\nMichael\",\n \"msg_date\": \"Wed, 27 Oct 2021 10:55:31 +0900\",\n \"msg_from\": \"Michael Paquier <michael@paquier.xyz>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"At Wed, 27 Oct 2021 10:55:31 +0900, Michael Paquier <michael@paquier.xyz> wrote in \\n> On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\\n> > I don't know. The fact is that it's a superuser-backend variable that\\n> > is silently ignored (but acutally seems to be set in the session).\\n> > Setting log_disconnection the same way works (of course the impliction\\n> > of this is far less significant that the log_connection case).\\n> \\n> fe550b2 is the commit that has changed both those parameters to be\\n> PGC_SU_BACKEND, with the commit log mentioning the case you are\\n> describing. That would be the area of this thread:\\n> https://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\\n\\nThanks for the pointer. (I didn't remember of that thread..)\\n\\n> As Tom and this thread are saying, there may be a use-case for\\n> making log_connections more effective at startup so as superusers\\n> could hide their logs at will. However, honestly, I am not sure that\\n> this is worth spending time improving this as the use-case looks\\n> rather thin to me. Perhaps you are right and we could just mark both\\n\\nI tend to agree.\\n\\n> of those GUCs as PGC_SIGHUP, making the whole easier to understand and\\n> more consistent, though. If we do that, the patch is wrong, as the\\n> docs would also need a refresh.\\n\\nYeah, this is the full version of the patch.\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\",\n \"msg_date\": \"Wed, 27 Oct 2021 11:53:09 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"\\nThis patch is from October of 2021. I don't see any commitfest entry\\nfor it. Should it be applied?\\n\\n---------------------------------------------------------------------------\\n\\nOn Wed, Oct 27, 2021 at 11:53:09AM +0900, Kyotaro Horiguchi wrote:\\n> At Wed, 27 Oct 2021 10:55:31 +0900, Michael Paquier <michael@paquier.xyz> wrote in \\n> > On Wed, Oct 27, 2021 at 10:24:05AM +0900, Kyotaro Horiguchi wrote:\\n> > > I don't know. The fact is that it's a superuser-backend variable that\\n> > > is silently ignored (but acutally seems to be set in the session).\\n> > > Setting log_disconnection the same way works (of course the impliction\\n> > > of this is far less significant that the log_connection case).\\n> > \\n> > fe550b2 is the commit that has changed both those parameters to be\\n> > PGC_SU_BACKEND, with the commit log mentioning the case you are\\n> > describing. That would be the area of this thread:\\n> > https://www.postgresql.org/message-id/20408.1404329822@sss.pgh.pa.us\\n> \\n> Thanks for the pointer. (I didn't remember of that thread..)\\n> \\n> > As Tom and this thread are saying, there may be a use-case for\\n> > making log_connections more effective at startup so as superusers\\n> > could hide their logs at will. However, honestly, I am not sure that\\n> > this is worth spending time improving this as the use-case looks\\n> > rather thin to me. Perhaps you are right and we could just mark both\\n> \\n> I tend to agree.\\n> \\n> > of those GUCs as PGC_SIGHUP, making the whole easier to understand and\\n> > more consistent, though. If we do that, the patch is wrong, as the\\n> > docs would also need a refresh.\\n> \\n> Yeah, this is the full version of the patch.\\n> \\n> regards.\\n> \\n> -- \\n> Kyotaro Horiguchi\\n> NTT Open Source Software Center\\n\\n> >From 11a9612c2590f57f431c3918d5b62c08a5b29efb Mon Sep 17 00:00:00 2001\\n> From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>\\n> Date: Wed, 27 Oct 2021 11:39:02 +0900\\n> Subject: [PATCH] Change log_(dis)connections to PGC_SIGHUP\\n> \\n> log_connections is not effective when it is given in connection\\n> options. Since no complaint has been heard for this behavior the\\n> use-case looks rather thin. Thus we change it to PGC_SIGHUP, rahther\\n> than putting efforts to make it effective for the\\n> use-case. log_disconnections is working with the usage but be\\n> consistent by treating it the same way with log_connection.\\n> ---\\n> doc/src/sgml/config.sgml | 8 ++++----\\n> src/backend/utils/misc/guc.c | 4 ++--\\n> 2 files changed, 6 insertions(+), 6 deletions(-)\\n> \\n> diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml\\n> index de77f14573..64b04a47d2 100644\\n> --- a/doc/src/sgml/config.sgml\\n> +++ b/doc/src/sgml/config.sgml\\n> @@ -6800,8 +6800,8 @@ local0.* /var/log/postgresql\\n> Causes each attempted connection to the server to be logged,\\n> as well as successful completion of both client authentication (if\\n> necessary) and authorization.\\n> - Only superusers can change this parameter at session start,\\n> - and it cannot be changed at all within a session.\\n> + This parameter can only be set in the <filename>postgresql.conf</filename>\\n> + file or on the server command line.\\n> The default is <literal>off</literal>.\\n> </para>\\n> \\n> @@ -6827,8 +6827,8 @@ local0.* /var/log/postgresql\\n> Causes session terminations to be logged. The log output\\n> provides information similar to <varname>log_connections</varname>,\\n> plus the duration of the session.\\n> - Only superusers can change this parameter at session start,\\n> - and it cannot be changed at all within a session.\\n> + This parameter can only be set in the <filename>postgresql.conf</filename>\\n> + file or on the server command line.\\n> The default is <literal>off</literal>.\\n> </para>\\n> </listitem>\\n> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c\\n> index e91d5a3cfd..57d810c80d 100644\\n> --- a/src/backend/utils/misc/guc.c\\n> +++ b/src/backend/utils/misc/guc.c\\n> @@ -1353,7 +1353,7 @@ static struct config_bool ConfigureNamesBool[] =\\n> \\t\\tNULL, NULL, NULL\\n> \\t},\\n> \\t{\\n> -\\t\\t{\\\"log_connections\\\", PGC_SU_BACKEND, LOGGING_WHAT,\\n> +\\t\\t{\\\"log_connections\\\", PGC_SIGHUP, LOGGING_WHAT,\\n> \\t\\t\\tgettext_noop(\\\"Logs each successful connection.\\\"),\\n> \\t\\t\\tNULL\\n> \\t\\t},\\n> @@ -1362,7 +1362,7 @@ static struct config_bool ConfigureNamesBool[] =\\n> \\t\\tNULL, NULL, NULL\\n> \\t},\\n> \\t{\\n> -\\t\\t{\\\"log_disconnections\\\", PGC_SU_BACKEND, LOGGING_WHAT,\\n> +\\t\\t{\\\"log_disconnections\\\", PGC_SIGHUP, LOGGING_WHAT,\\n> \\t\\t\\tgettext_noop(\\\"Logs end of a session, including duration.\\\"),\\n> \\t\\t\\tNULL\\n> \\t\\t},\\n> -- \\n> 2.27.0\\n> \\n\\n\\n-- \\n Bruce Momjian <bruce@momjian.us> https://momjian.us\\n EDB https://enterprisedb.com\\n\\n Indecision is a decision. Inaction is an action. Mark Batterson\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Aug 2022 10:23:06 -0400\",\n \"msg_from\": \"Bruce Momjian <bruce@momjian.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"Bruce Momjian <bruce@momjian.us> writes:\\n> This patch is from October of 2021. I don't see any commitfest entry\\n> for it. Should it be applied?\\n\\nI think we decided not to. The original argument for having these\\nbe PGC_SU_BACKEND was to try to ensure that you got matching\\nconnection and disconnection log entries for any one session,\\nand I don't see anything that supersedes that plan.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Aug 2022 10:29:26 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n },\n {\n \"msg_contents\": \"On Wed, Aug 17, 2022 at 10:29:26AM -0400, Tom Lane wrote:\\n> Bruce Momjian <bruce@momjian.us> writes:\\n> > This patch is from October of 2021. I don't see any commitfest entry\\n> > for it. Should it be applied?\\n> \\n> I think we decided not to. The original argument for having these\\n> be PGC_SU_BACKEND was to try to ensure that you got matching\\n> connection and disconnection log entries for any one session,\\n> and I don't see anything that supersedes that plan.\\n\\nOkay, thanks for the feedback.\\n\\n-- \\n Bruce Momjian <bruce@momjian.us> https://momjian.us\\n EDB https://enterprisedb.com\\n\\n Indecision is a decision. Inaction is an action. Mark Batterson\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Aug 2022 10:30:16 -0400\",\n \"msg_from\": \"Bruce Momjian <bruce@momjian.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Setting log_connection in connection string doesn't work\"\n }\n]","isConversational":false}}},{"rowIdx":52992,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"src/port/snprintf.c: Optimize the common base=10 case in fmtint\n\nfmtint() turns an integer into a string for a given base, and to do this\nit does a divide/modulo operation iteratively.\n\nOn just about any CPU, divides are a pretty expensive operation, generally\n10x to 20x or more expensive than adds or multiplies.\n\nBy special casing the super common case of base==10, the (gcc) compiler can (and will)\nreplace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\n(fmtint dropped drastically in the perf profiles after this change)\n\nEven though this only shows up in the database creation phase of pgbench and not so much\nduring the normal run time, the optimization is simple and high value enough that\nin my opinion it's worth doing\n\n\n\n\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\nindex 7c21429369..5957e6f2aa 100644\n--- a/src/port/snprintf.c\n+++ b/src/port/snprintf.c\n@@ -1076,11 +1076,24 @@ fmtint(long long value, char type, int forcesign, int leftjust,\n \telse\n \t{\n \t\t/* make integer string */\n-\t\tdo\n-\t\t{\n-\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n-\t\t\tuvalue = uvalue / base;\n-\t\t} while (uvalue);\n+\n+\t\t/*\n+\t\t * Special case a base of 10 because it is super common and by special casing the compiler can\n+\t\t * avoid an expensive divide operation (the compiler will use a multiply for this)\n+\t\t */\n+\t\tif (likely(base == 10)) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\n+\t\t\t\tuvalue = uvalue / 10;\n+\t\t\t} while (uvalue);\n+\t\t} else {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n+\t\t\t\tuvalue = uvalue / base;\n+\t\t\t} while (uvalue);\n+\t\t}\n \t}\n\n \tzeropad = Max(0, precision - vallen);\n\n\n","msg_date":"Tue, 26 Oct 2021 07:57:36 -0700","msg_from":"Arjan van de Ven <arjan@linux.intel.com>","msg_from_op":true,"msg_subject":"src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"\n\n> On Oct 26, 2021, at 7:57 AM, Arjan van de Ven <arjan@linux.intel.com> wrote:\n> \n> By special casing the super common case of base==10, the (gcc) compiler can (and will)\n> replace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\n> (fmtint dropped drastically in the perf profiles after this change)\n\nIt appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \"%08X%08X%08X\".\n\n—\nMark Dilger\nEnterpriseDB: http://www.enterprisedb.com\nThe Enterprise PostgreSQL Company\n\n\n\n\n\n","msg_date":"Tue, 26 Oct 2021 09:45:32 -0700","msg_from":"Mark Dilger <mark.dilger@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"Hi,\n\nOn 2021-10-26 07:57:36 -0700, Arjan van de Ven wrote:\n> src/port/snprintf.c: Optimize the common base=10 case in fmtint\n> \n> fmtint() turns an integer into a string for a given base, and to do this\n> it does a divide/modulo operation iteratively.\n> \n> On just about any CPU, divides are a pretty expensive operation, generally\n> 10x to 20x or more expensive than adds or multiplies.\n\nThis has been bothering me too, thanks for doing something about it.\n\n\n> By special casing the super common case of base==10, the (gcc) compiler can (and will)\n> replace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\n> (fmtint dropped drastically in the perf profiles after this change)\n> \n> Even though this only shows up in the database creation phase of pgbench and not so much\n> during the normal run time, the optimization is simple and high value enough that\n> in my opinion it's worth doing\n\nIt does even show up during normal running for me, in readonly pgbench.\n\n\n> diff --git a/src/port/snprintf.c b/src/port/snprintf.c\n> index 7c21429369..5957e6f2aa 100644\n> --- a/src/port/snprintf.c\n> +++ b/src/port/snprintf.c\n> @@ -1076,11 +1076,24 @@ fmtint(long long value, char type, int forcesign, int leftjust,\n> \telse\n> \t{\n> \t\t/* make integer string */\n> -\t\tdo\n> -\t\t{\n> -\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n> -\t\t\tuvalue = uvalue / base;\n> -\t\t} while (uvalue);\n> +\n> +\t\t/*\n> +\t\t * Special case a base of 10 because it is super common and by special casing the compiler can\n> +\t\t * avoid an expensive divide operation (the compiler will use a multiply for this)\n> +\t\t */\n> +\t\tif (likely(base == 10)) {\n> +\t\t\tdo\n> +\t\t\t{\n> +\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\n> +\t\t\t\tuvalue = uvalue / 10;\n> +\t\t\t} while (uvalue);\n> +\t\t} else {\n> +\t\t\tdo\n> +\t\t\t{\n> +\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n> +\t\t\t\tuvalue = uvalue / base;\n> +\t\t\t} while (uvalue);\n> +\t\t}\n> \t}\n> \n> \tzeropad = Max(0, precision - vallen);\n\nSince all the bases are known / set earlier in the function, it seems better\nto just split the function into two, with the new helper doing the conversion.\n\nIt's harder than it should be, because that code is a bit, uh, tangled, but I\nthink I can see a way through...\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 26 Oct 2021 09:56:44 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"Mark Dilger <mark.dilger@enterprisedb.com> writes:\n> It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \"%08X%08X%08X\".\n\nI'd be inclined to just hard-wire the three allowed cases, and not have\nan arbitrary-divisor code path at all.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 13:51:55 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"On 10/26/2021 10:51 AM, Tom Lane wrote:\n> Mark Dilger <mark.dilger@enterprisedb.com> writes:\n>> It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \"%08X%08X%08X\".\n> \n> I'd be inclined to just hard-wire the three allowed cases, and not have\n> an arbitrary-divisor code path at all.\n> \n\nok so feedback is \"Yes please but we want more of it\" :)\n\nI'll go poke at making an updated patch that does 8/10/16 and nothing else.\n\n\n\n\n","msg_date":"Tue, 26 Oct 2021 11:13:14 -0700","msg_from":"Arjan van de Ven <arjan@linux.intel.com>","msg_from_op":true,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"Hi,\n\nOn 2021-10-26 13:51:55 -0400, Tom Lane wrote:\n> Mark Dilger <mark.dilger@enterprisedb.com> writes:\n> > It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \"%08X%08X%08X\".\n> \n> I'd be inclined to just hard-wire the three allowed cases, and not have\n> an arbitrary-divisor code path at all.\n\nYea, I came to the same conclusion. But I'd implement it by moving the\ndivision into a separate inline function called from the switch. I tested that\nlocally and it works, but I got sidetracked by [1].\n\nGreetings,\n\nAndres Freund\n\n[1] https://postgr.es/m/20211026180454.xcjmu3kwmn3tka57%40alap3.anarazel.de\n\n\n","msg_date":"Tue, 26 Oct 2021 11:15:35 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> On 2021-10-26 13:51:55 -0400, Tom Lane wrote:\n>> I'd be inclined to just hard-wire the three allowed cases, and not have\n>> an arbitrary-divisor code path at all.\n\n> Yea, I came to the same conclusion. But I'd implement it by moving the\n> division into a separate inline function called from the switch. I tested that\n> locally and it works, but I got sidetracked by [1].\n\nUh, why not just a \"switch (base)\" around three copies of the loop?\nDon't overthink this.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 14:33:08 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"},{"msg_contents":"Hi,\n\nOn 2021-10-26 14:33:08 -0400, Tom Lane wrote:\n> Andres Freund <andres@anarazel.de> writes:\n> > On 2021-10-26 13:51:55 -0400, Tom Lane wrote:\n> >> I'd be inclined to just hard-wire the three allowed cases, and not have\n> >> an arbitrary-divisor code path at all.\n>\n> > Yea, I came to the same conclusion. But I'd implement it by moving the\n> > division into a separate inline function called from the switch. I tested that\n> > locally and it works, but I got sidetracked by [1].\n>\n> Uh, why not just a \"switch (base)\" around three copies of the loop?\n> Don't overthink this.\n\nWell, putting the loop into its own function isn't really much more\ncomplicated than duplicating the body. And there's also a few more\n\"unnecessarily run-time\" branches that we could get rid of that way.\n\nBut I'm also ok with duplicating, at least for now.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 26 Oct 2021 11:58:31 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint"}],"string":"[\n {\n \"msg_contents\": \"src/port/snprintf.c: Optimize the common base=10 case in fmtint\\n\\nfmtint() turns an integer into a string for a given base, and to do this\\nit does a divide/modulo operation iteratively.\\n\\nOn just about any CPU, divides are a pretty expensive operation, generally\\n10x to 20x or more expensive than adds or multiplies.\\n\\nBy special casing the super common case of base==10, the (gcc) compiler can (and will)\\nreplace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\\n(fmtint dropped drastically in the perf profiles after this change)\\n\\nEven though this only shows up in the database creation phase of pgbench and not so much\\nduring the normal run time, the optimization is simple and high value enough that\\nin my opinion it's worth doing\\n\\n\\n\\n\\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\\nindex 7c21429369..5957e6f2aa 100644\\n--- a/src/port/snprintf.c\\n+++ b/src/port/snprintf.c\\n@@ -1076,11 +1076,24 @@ fmtint(long long value, char type, int forcesign, int leftjust,\\n \\telse\\n \\t{\\n \\t\\t/* make integer string */\\n-\\t\\tdo\\n-\\t\\t{\\n-\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n-\\t\\t\\tuvalue = uvalue / base;\\n-\\t\\t} while (uvalue);\\n+\\n+\\t\\t/*\\n+\\t\\t * Special case a base of 10 because it is super common and by special casing the compiler can\\n+\\t\\t * avoid an expensive divide operation (the compiler will use a multiply for this)\\n+\\t\\t */\\n+\\t\\tif (likely(base == 10)) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\\n+\\t\\t\\t\\tuvalue = uvalue / 10;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n+\\t\\t\\t\\tuvalue = uvalue / base;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t}\\n \\t}\\n\\n \\tzeropad = Max(0, precision - vallen);\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 07:57:36 -0700\",\n \"msg_from\": \"Arjan van de Ven <arjan@linux.intel.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"\\n\\n> On Oct 26, 2021, at 7:57 AM, Arjan van de Ven <arjan@linux.intel.com> wrote:\\n> \\n> By special casing the super common case of base==10, the (gcc) compiler can (and will)\\n> replace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\\n> (fmtint dropped drastically in the perf profiles after this change)\\n\\nIt appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \\\"%08X%08X%08X\\\".\\n\\n—\\nMark Dilger\\nEnterpriseDB: http://www.enterprisedb.com\\nThe Enterprise PostgreSQL Company\\n\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 09:45:32 -0700\",\n \"msg_from\": \"Mark Dilger <mark.dilger@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-26 07:57:36 -0700, Arjan van de Ven wrote:\\n> src/port/snprintf.c: Optimize the common base=10 case in fmtint\\n> \\n> fmtint() turns an integer into a string for a given base, and to do this\\n> it does a divide/modulo operation iteratively.\\n> \\n> On just about any CPU, divides are a pretty expensive operation, generally\\n> 10x to 20x or more expensive than adds or multiplies.\\n\\nThis has been bothering me too, thanks for doing something about it.\\n\\n\\n> By special casing the super common case of base==10, the (gcc) compiler can (and will)\\n> replace the divide by a multiply with 0xcccccccccccccccd, yielding a lot faster code.\\n> (fmtint dropped drastically in the perf profiles after this change)\\n> \\n> Even though this only shows up in the database creation phase of pgbench and not so much\\n> during the normal run time, the optimization is simple and high value enough that\\n> in my opinion it's worth doing\\n\\nIt does even show up during normal running for me, in readonly pgbench.\\n\\n\\n> diff --git a/src/port/snprintf.c b/src/port/snprintf.c\\n> index 7c21429369..5957e6f2aa 100644\\n> --- a/src/port/snprintf.c\\n> +++ b/src/port/snprintf.c\\n> @@ -1076,11 +1076,24 @@ fmtint(long long value, char type, int forcesign, int leftjust,\\n> \\telse\\n> \\t{\\n> \\t\\t/* make integer string */\\n> -\\t\\tdo\\n> -\\t\\t{\\n> -\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n> -\\t\\t\\tuvalue = uvalue / base;\\n> -\\t\\t} while (uvalue);\\n> +\\n> +\\t\\t/*\\n> +\\t\\t * Special case a base of 10 because it is super common and by special casing the compiler can\\n> +\\t\\t * avoid an expensive divide operation (the compiler will use a multiply for this)\\n> +\\t\\t */\\n> +\\t\\tif (likely(base == 10)) {\\n> +\\t\\t\\tdo\\n> +\\t\\t\\t{\\n> +\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\\n> +\\t\\t\\t\\tuvalue = uvalue / 10;\\n> +\\t\\t\\t} while (uvalue);\\n> +\\t\\t} else {\\n> +\\t\\t\\tdo\\n> +\\t\\t\\t{\\n> +\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n> +\\t\\t\\t\\tuvalue = uvalue / base;\\n> +\\t\\t\\t} while (uvalue);\\n> +\\t\\t}\\n> \\t}\\n> \\n> \\tzeropad = Max(0, precision - vallen);\\n\\nSince all the bases are known / set earlier in the function, it seems better\\nto just split the function into two, with the new helper doing the conversion.\\n\\nIt's harder than it should be, because that code is a bit, uh, tangled, but I\\nthink I can see a way through...\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 09:56:44 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"Mark Dilger <mark.dilger@enterprisedb.com> writes:\\n> It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \\\"%08X%08X%08X\\\".\\n\\nI'd be inclined to just hard-wire the three allowed cases, and not have\\nan arbitrary-divisor code path at all.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:51:55 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"On 10/26/2021 10:51 AM, Tom Lane wrote:\\n> Mark Dilger <mark.dilger@enterprisedb.com> writes:\\n>> It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \\\"%08X%08X%08X\\\".\\n> \\n> I'd be inclined to just hard-wire the three allowed cases, and not have\\n> an arbitrary-divisor code path at all.\\n> \\n\\nok so feedback is \\\"Yes please but we want more of it\\\" :)\\n\\nI'll go poke at making an updated patch that does 8/10/16 and nothing else.\\n\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:13:14 -0700\",\n \"msg_from\": \"Arjan van de Ven <arjan@linux.intel.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-26 13:51:55 -0400, Tom Lane wrote:\\n> Mark Dilger <mark.dilger@enterprisedb.com> writes:\\n> > It appears fmtint only has three options for base, being 10, 16, and 8. Have you profiled with either of the others special cased as well? I don't see much use in optimizing for octal, but hexadecimal is used quite a bit in wal with patterns like \\\"%08X%08X%08X\\\".\\n> \\n> I'd be inclined to just hard-wire the three allowed cases, and not have\\n> an arbitrary-divisor code path at all.\\n\\nYea, I came to the same conclusion. But I'd implement it by moving the\\ndivision into a separate inline function called from the switch. I tested that\\nlocally and it works, but I got sidetracked by [1].\\n\\nGreetings,\\n\\nAndres Freund\\n\\n[1] https://postgr.es/m/20211026180454.xcjmu3kwmn3tka57%40alap3.anarazel.de\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:15:35 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> On 2021-10-26 13:51:55 -0400, Tom Lane wrote:\\n>> I'd be inclined to just hard-wire the three allowed cases, and not have\\n>> an arbitrary-divisor code path at all.\\n\\n> Yea, I came to the same conclusion. But I'd implement it by moving the\\n> division into a separate inline function called from the switch. I tested that\\n> locally and it works, but I got sidetracked by [1].\\n\\nUh, why not just a \\\"switch (base)\\\" around three copies of the loop?\\nDon't overthink this.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 14:33:08 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-26 14:33:08 -0400, Tom Lane wrote:\\n> Andres Freund <andres@anarazel.de> writes:\\n> > On 2021-10-26 13:51:55 -0400, Tom Lane wrote:\\n> >> I'd be inclined to just hard-wire the three allowed cases, and not have\\n> >> an arbitrary-divisor code path at all.\\n>\\n> > Yea, I came to the same conclusion. But I'd implement it by moving the\\n> > division into a separate inline function called from the switch. I tested that\\n> > locally and it works, but I got sidetracked by [1].\\n>\\n> Uh, why not just a \\\"switch (base)\\\" around three copies of the loop?\\n> Don't overthink this.\\n\\nWell, putting the loop into its own function isn't really much more\\ncomplicated than duplicating the body. And there's also a few more\\n\\\"unnecessarily run-time\\\" branches that we could get rid of that way.\\n\\nBut I'm also ok with duplicating, at least for now.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:58:31 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: src/port/snprintf.c: Optimize the common base=10 case in fmtint\"\n }\n]","isConversational":false}}},{"rowIdx":52993,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\n\nour make dependencies currently are insufficient to trigger client binaries to\nbe relinked when pgport/pgcommon/libpq/... changes.\n\nTo reproduce, you can use something like:\ntouch ~/src/postgresql/src/port/snprintf.c && make -j48 2>&1|grep 'gcc.*pgbench'\nwhich won't show anything, whereas e.g.\ntouch ~/src/postgresql/src/include/postgres_fe.h && make -j48 2>&1|grep 'gcc.*pgbench'\nwill.\n\nThe reason for that is that currently client programs only have order-only\ndependencies on pgport:\n\npgbench: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils\n\t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\n\nwhich will dutifully cause pgport to be rebuilt. But then we won't actually\nrebuild $client_program, because it's just an order-only dependency [1].\n\n\nThe same problem does *not* exist for the backend, because there we add\npgport/pgcommon to OBJS, which will cause them to be proper dependencies.\n\nThis does explain some mysterious issues I had over the years with changes\noccasionally requiring a clean/build cycle to fully take. It's especially\nconfusing because after a build cycle one ends up with a build partially using\nthe old and partially the new libraries.\n\n\nI unfortunately don't see a localized fix for this. Afaict we'd need to change\nall client build rules to also have a dependency on the library?\n\nGreetings,\n\nAndres Freund\n\n\n[1] https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html\n\n\n","msg_date":"Tue, 26 Oct 2021 11:04:54 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":true,"msg_subject":"changes in pgport etc doesn't cause client programs to be relinked"},{"msg_contents":"Hi,\n\nOn 2021-10-26 11:04:54 -0700, Andres Freund wrote:\n> pgbench: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils\n> \t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\n\n> I unfortunately don't see a localized fix for this. Afaict we'd need to change\n> all client build rules to also have a dependency on the library?\n\nFor a second I thought I had an elegant solution to this: Many linkers these\ndays support --dependency-file, similar to the way we deal with dependencies\nfor compilation.\n\nBut that doesn't work easily either, because we use $^ in at least some of the\nrecipes for building executables. Which will contain the generated library\ndependencies after the first build. That's easy enough to fix for things like\npgbench, where $^ is used directly, but there's also some binaries that we\nbuild using prefix rules.\n\nLike\n\n# Replace gmake's default rule for linking a single .o file to produce an\n# executable. The main point here is to put LDFLAGS after the .o file,\n# since we put -l switches into LDFLAGS and those are order-sensitive.\n# In addition, include CFLAGS and LDFLAGS_EX per project conventions.\n%: %.o\n\t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\n\nwhich, despite the comment, we not just use with a single object file, but\nalso with multiple ones, afaict. E.g. in src/bin/scripts/Makefile. With a\nsingle object file we could just replace $^ with $@.o, but...\n\nOf course we could filter $^ to only contain .o's, but at some point this\nisn't a simple solution anymore :(\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Tue, 26 Oct 2021 11:31:40 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":true,"msg_subject":"Re: changes in pgport etc doesn't cause client programs to be\n relinked"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\n\\nour make dependencies currently are insufficient to trigger client binaries to\\nbe relinked when pgport/pgcommon/libpq/... changes.\\n\\nTo reproduce, you can use something like:\\ntouch ~/src/postgresql/src/port/snprintf.c && make -j48 2>&1|grep 'gcc.*pgbench'\\nwhich won't show anything, whereas e.g.\\ntouch ~/src/postgresql/src/include/postgres_fe.h && make -j48 2>&1|grep 'gcc.*pgbench'\\nwill.\\n\\nThe reason for that is that currently client programs only have order-only\\ndependencies on pgport:\\n\\npgbench: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils\\n\\t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\\n\\nwhich will dutifully cause pgport to be rebuilt. But then we won't actually\\nrebuild $client_program, because it's just an order-only dependency [1].\\n\\n\\nThe same problem does *not* exist for the backend, because there we add\\npgport/pgcommon to OBJS, which will cause them to be proper dependencies.\\n\\nThis does explain some mysterious issues I had over the years with changes\\noccasionally requiring a clean/build cycle to fully take. It's especially\\nconfusing because after a build cycle one ends up with a build partially using\\nthe old and partially the new libraries.\\n\\n\\nI unfortunately don't see a localized fix for this. Afaict we'd need to change\\nall client build rules to also have a dependency on the library?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n[1] https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:04:54 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"changes in pgport etc doesn't cause client programs to be relinked\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-26 11:04:54 -0700, Andres Freund wrote:\\n> pgbench: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils\\n> \\t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\\n\\n> I unfortunately don't see a localized fix for this. Afaict we'd need to change\\n> all client build rules to also have a dependency on the library?\\n\\nFor a second I thought I had an elegant solution to this: Many linkers these\\ndays support --dependency-file, similar to the way we deal with dependencies\\nfor compilation.\\n\\nBut that doesn't work easily either, because we use $^ in at least some of the\\nrecipes for building executables. Which will contain the generated library\\ndependencies after the first build. That's easy enough to fix for things like\\npgbench, where $^ is used directly, but there's also some binaries that we\\nbuild using prefix rules.\\n\\nLike\\n\\n# Replace gmake's default rule for linking a single .o file to produce an\\n# executable. The main point here is to put LDFLAGS after the .o file,\\n# since we put -l switches into LDFLAGS and those are order-sensitive.\\n# In addition, include CFLAGS and LDFLAGS_EX per project conventions.\\n%: %.o\\n\\t$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)\\n\\nwhich, despite the comment, we not just use with a single object file, but\\nalso with multiple ones, afaict. E.g. in src/bin/scripts/Makefile. With a\\nsingle object file we could just replace $^ with $@.o, but...\\n\\nOf course we could filter $^ to only contain .o's, but at some point this\\nisn't a simple solution anymore :(\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 11:31:40 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: changes in pgport etc doesn't cause client programs to be\\n relinked\"\n }\n]","isConversational":false}}},{"rowIdx":52994,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\r\n\r\nSince PostgreSQL 12 (0516c61b756e39) we have allowed for the ability to \r\nset \"clientcert=verify-full\" against various HBA authentication methods. \r\nThis provides the ability to provide \"multi-factor authentication\" e.g. \r\na client must provide both a valid certificate with a CN (or DN) that \r\nmatches the user account, as well as a separate authentication challenge \r\n(e.g. a password).\r\n\r\nWith certificate-based authentication methods and other methods, we \r\nallow for users to specify a mapping in pg_ident, e.g. if one needs to \r\nperform a rewrite on the CN to match the username that is specified \r\nwithin PostgreSQL.\r\n\r\nIt seems logical that we should allow for something like:\r\n\r\n\thostssl all all all scram-sha-256 clientcert=verify-full map=map\r\n\r\nso we can accept certificates that may have CNs that can be mapped to a \r\nPostgreSQL user name.\r\n\r\nCurrently we can't do this, as one will get the error:\r\n\r\n > authentication option \"map\" is only valid for authentication methods\r\n > ident, peer, gssapi, sspi, and cert\r\n\r\nI propose the below patch to add the currently supported password \r\nmethods, scram-sha-256 + md5 to allow for the \"map\" parameter to be \r\nused. I hesitate to add md5 given we're trying to phase it out, so open \r\nto debate there.\r\n\r\nWith my testing, this does work when you specify clientcert=verify-full: \r\nPostgreSQL will correctly map the certificate. If you do not have \r\nclientcert=verify-full, the mapping appears to do nothing.\r\n\r\nIf this seems acceptable/valid, I'll add the appropriate documentation \r\nand whatever else may be required.\r\n\r\nThanks,\r\n\r\nJonathan","msg_date":"Tue, 26 Oct 2021 14:59:19 -0400","msg_from":"\"Jonathan S. Katz\" <jkatz@postgresql.org>","msg_from_op":true,"msg_subject":"allowing \"map\" for password auth methods with clientcert=verify-full"},{"msg_contents":"\"Jonathan S. Katz\" <jkatz@postgresql.org> writes:\n> With certificate-based authentication methods and other methods, we \n> allow for users to specify a mapping in pg_ident, e.g. if one needs to \n> perform a rewrite on the CN to match the username that is specified \n> within PostgreSQL.\n\n> It seems logical that we should allow for something like:\n> \thostssl all all all scram-sha-256 clientcert=verify-full map=map\n> so we can accept certificates that may have CNs that can be mapped to a \n> PostgreSQL user name.\n\nI think this is conflating two different things: a mapping from the\nusername given in the startup packet, and a mapping from the TLS\ncertificate CN. Using the same keyword and terminology for both\nis going to lead to pain. I'm on board with the idea if we can\ndisentangle that, though.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 15:26:08 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On 10/26/21 3:26 PM, Tom Lane wrote:\r\n> \"Jonathan S. Katz\" <jkatz@postgresql.org> writes:\r\n>> With certificate-based authentication methods and other methods, we\r\n>> allow for users to specify a mapping in pg_ident, e.g. if one needs to\r\n>> perform a rewrite on the CN to match the username that is specified\r\n>> within PostgreSQL.\r\n> \r\n>> It seems logical that we should allow for something like:\r\n>> \thostssl all all all scram-sha-256 clientcert=verify-full map=map\r\n>> so we can accept certificates that may have CNs that can be mapped to a\r\n>> PostgreSQL user name.\r\n> \r\n> I think this is conflating two different things: a mapping from the\r\n> username given in the startup packet, and a mapping from the TLS\r\n> certificate CN. Using the same keyword and terminology for both\r\n> is going to lead to pain. I'm on board with the idea if we can\r\n> disentangle that, though.\r\n\r\nHm, don't we already have that already when using \"cert\" combined with \r\nthe \"map\" parameter? This is the main reason I \"stumbled\" upon this \r\nrecommendation.\r\n\r\nBased on what you say and if we're continuing with this functionality, \r\nwould solving the conflation be a matter of primarily documentation?\r\n\r\nThanks,\r\n\r\nJonathan","msg_date":"Tue, 26 Oct 2021 16:04:01 -0400","msg_from":"\"Jonathan S. Katz\" <jkatz@postgresql.org>","msg_from_op":true,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"\"Jonathan S. Katz\" <jkatz@postgresql.org> writes:\n> On 10/26/21 3:26 PM, Tom Lane wrote:\n>> I think this is conflating two different things: a mapping from the\n>> username given in the startup packet, and a mapping from the TLS\n>> certificate CN. Using the same keyword and terminology for both\n>> is going to lead to pain. I'm on board with the idea if we can\n>> disentangle that, though.\n\n> Hm, don't we already have that already when using \"cert\" combined with \n> the \"map\" parameter? This is the main reason I \"stumbled\" upon this \n> recommendation.\n\nI'm not exactly convinced that the existing design is any good.\nI'm suggesting that we stop and think about it before propagating\nit to a bunch of other use-cases.\n\nPer \"21.2. User Name Maps\", I think that the map parameter is supposed\nto translate from the startup packet's user name to the SQL role name.\nISTM that what is in the cert CN might be different from either\n(particularly by perhaps having a domain name attached). So I'd be\nhappier if there were a separate mapping available for the CN.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 18:16:34 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"\nOn 10/26/21 18:16, Tom Lane wrote:\n> \"Jonathan S. Katz\" <jkatz@postgresql.org> writes:\n>> On 10/26/21 3:26 PM, Tom Lane wrote:\n>>> I think this is conflating two different things: a mapping from the\n>>> username given in the startup packet, and a mapping from the TLS\n>>> certificate CN. Using the same keyword and terminology for both\n>>> is going to lead to pain. I'm on board with the idea if we can\n>>> disentangle that, though.\n>> Hm, don't we already have that already when using \"cert\" combined with \n>> the \"map\" parameter? This is the main reason I \"stumbled\" upon this \n>> recommendation.\n> I'm not exactly convinced that the existing design is any good.\n> I'm suggesting that we stop and think about it before propagating\n> it to a bunch of other use-cases.\n>\n> Per \"21.2. User Name Maps\", I think that the map parameter is supposed\n> to translate from the startup packet's user name to the SQL role name.\n> ISTM that what is in the cert CN might be different from either\n> (particularly by perhaps having a domain name attached). So I'd be\n> happier if there were a separate mapping available for the CN.\n>\n> \t\t\t\n\n\nPossibly slightly off topic, but\n\nThe cert+map pattern is very useful in conjunction with pgbouncer. Using\nit with an auth query to get the password pgbouncer doesn't even need to\nhave a list of users, and we in effect delegate authentication to\npgbouncer.\n\nIt would be nice to have + and @ expansion for the usernames in the\nident file, like there is for pg_hba.conf.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com\n\n\n\n","msg_date":"Wed, 27 Oct 2021 10:12:46 -0400","msg_from":"Andrew Dunstan <andrew@dunslane.net>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On Tue, 2021-10-26 at 18:16 -0400, Tom Lane wrote:\r\n> Per \"21.2. User Name Maps\", I think that the map parameter is supposed\r\n> to translate from the startup packet's user name to the SQL role name.\r\n\r\nI may have misunderstood what you wrote, but IIUC the startup packet's\r\nuser name _is_ the SQL role name, even when using a map. The map is\r\njust determining whether or not the authenticated ID (pulled from a\r\ncertificate, or from Kerberos, or etc.) is authorized to use that role\r\nname. It's not a translation, because you can have a one-to-many user\r\nmapping (where me@example.com is allowed to log in as `me` or\r\n`postgres` or `admin` or...).\r\n\r\nPlease correct me if I've missed something -- I need to have it right\r\nin my head, given my other patches in this area...\r\n\r\n--Jacob\r\n","msg_date":"Wed, 27 Oct 2021 16:14:45 +0000","msg_from":"Jacob Champion <pchampion@vmware.com>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On Wed, 2021-10-27 at 10:12 -0400, Andrew Dunstan wrote:\r\n> Possibly slightly off topic, but\r\n> \r\n> The cert+map pattern is very useful in conjunction with pgbouncer. Using\r\n> it with an auth query to get the password pgbouncer doesn't even need to\r\n> have a list of users, and we in effect delegate authentication to\r\n> pgbouncer.\r\n> \r\n> It would be nice to have + and @ expansion for the usernames in the\r\n> ident file, like there is for pg_hba.conf.\r\n\r\n(Probably is off-topic :D but +1 to the concept. Combined with LDAP\r\nmapping that could make some of the ad-hoc LDAP-to-Postgres sync\r\nscripts a lot simpler.)\r\n\r\n--Jacob\r\n","msg_date":"Wed, 27 Oct 2021 16:49:21 +0000","msg_from":"Jacob Champion <pchampion@vmware.com>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On 10/27/21 12:14 PM, Jacob Champion wrote:\r\n> On Tue, 2021-10-26 at 18:16 -0400, Tom Lane wrote:\r\n>> Per \"21.2. User Name Maps\", I think that the map parameter is supposed\r\n>> to translate from the startup packet's user name to the SQL role name.\r\n> \r\n> I may have misunderstood what you wrote, but IIUC the startup packet's\r\n> user name _is_ the SQL role name, even when using a map. The map is\r\n> just determining whether or not the authenticated ID (pulled from a\r\n> certificate, or from Kerberos, or etc.) is authorized to use that role\r\n> name. It's not a translation, because you can have a one-to-many user\r\n> mapping (where me@example.com is allowed to log in as `me` or\r\n> `postgres` or `admin` or...).\r\n> \r\n> Please correct me if I've missed something -- I need to have it right\r\n> in my head, given my other patches in this area...\r\n\r\nTo Tom's earlier point, I understand why we may want to pause and think \r\nabout this.\r\n\r\nI don't know the whole history of the \"pg_ident.conf\" file, but judging \r\nby the name, my guess is that the mapping functionality started with the \r\n\"ident\" authentication support, and then it was used for other auth \r\ntypes that could benefit from mapping (cert/gssapi etc.). The \r\ndocumentation referenced also skews towards describing what the original \r\nfunctionality for ident does.\r\n\r\nThat said, the existing functionality does match what Jacob is \r\ndescribing and what my own understanding is.\r\n\r\nThe patch I propose just layers on top of the existing functionality -- \r\n you could even argue that it's \"fixing a bug\" that we did not add the \r\ncurrent \"map\" support for the case of \"clientcert=verify-full\" given we \r\ndo introspect the certificate CN to see if it matches the SQL role name.\r\n\r\nIn terms of other user mapping functionality, we have ad hoc support for \r\nFDWs when trying to map to a user in a different server:\r\n\r\nhttps://www.postgresql.org/docs/current/sql-createusermapping.html\r\n\r\nI'm unsure if there is anything we'd want to leverage here, as the \r\noverall goal of this is to provide the ability to establish a connection \r\nwith a remote server.\r\n\r\nI think in the context of doing any new work, I'd step back and ask what \r\nproblem is this solving? The main one I think of is an integration with \r\na SSO system has a credential with an identifier that does not match \r\nit's credential in PostgreSQL? (That would be the case I was working on, \r\nthough said case was borrowed from our docs). Are there other cases?\r\n\r\nThat said, what would make it easier to manage it then? Maybe a lot of \r\nthis is documenting and some expansion on what the pg_ident.conf file \r\ncan do (per Andrew's suggestion). And maybe a new name for said file.\r\n\r\nI don't know if we would want to bring any of this into the catalog or \r\nnot -- but perhaps there may be some advantages to that from an \r\nadministration standpoint.\r\n\r\nAnyway, those are my initial thoughts on the challenge to think a bit \r\nmore deeply about this. I'd still suggest considering the patch I \r\npropose as an \"immediate fix\" for existing versions as, at least to \r\nmyself, I can argue it's a bug. We can then do some more work to make \r\nthe overall system a bit easier/clearer to use and maintain.\r\n\r\nThanks,\r\n\r\nJonathan","msg_date":"Wed, 27 Oct 2021 12:53:44 -0400","msg_from":"\"Jonathan S. Katz\" <jkatz@postgresql.org>","msg_from_op":true,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On Wed, 2021-10-27 at 12:53 -0400, Jonathan S. Katz wrote:\r\n> The patch I propose just layers on top of the existing functionality -- \r\n> you could even argue that it's \"fixing a bug\" that we did not add the \r\n> current \"map\" support for the case of \"clientcert=verify-full\" given we \r\n> do introspect the certificate CN to see if it matches the SQL role name.\r\n\r\nWell, also to Tom's earlier point, though, this is a different sort of\r\nmapping. Which \"map\" should we use if someone combines\r\nclientcert=verify-full with an auth method which already uses a map\r\nitself? Does the DBA want to map the auth name, the cert name, or both?\r\n\r\nThe current usermap support is piecemeal and I'd like to see it\r\ncompleted, but I think you may be painting yourself into a corner if\r\nyou fix it in this way. (From a quick look at the patch, I'm also\r\nworried that this happens to work by accident, but that may just be\r\nFUD.)\r\n\r\n> I think in the context of doing any new work, I'd step back and ask what \r\n> problem is this solving? The main one I think of is an integration with \r\n> a SSO system has a credential with an identifier that does not match \r\n> it's credential in PostgreSQL? (That would be the case I was working on, \r\n> though said case was borrowed from our docs). Are there other cases?\r\n> \r\n> That said, what would make it easier to manage it then? Maybe a lot of \r\n> this is documenting and some expansion on what the pg_ident.conf file \r\n> can do (per Andrew's suggestion). And maybe a new name for said file.\r\n\r\nI agree that the authorization system is due for a tuneup, for what\r\nit's worth. Some of the comments from Magnus on my LDAP patch [1] kind\r\nof hinted in that direction as well, I think, even if my approach is\r\nrejected in the end.\r\n\r\n--Jacob\r\n\r\n[1] https://www.postgresql.org/message-id/flat/1a61806047c536e7528b943d0cfe12608118ca31.camel@vmware.com\r\n","msg_date":"Wed, 27 Oct 2021 17:37:49 +0000","msg_from":"Jacob Champion <pchampion@vmware.com>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"Greetings,\n\n* Jacob Champion (pchampion@vmware.com) wrote:\n> On Wed, 2021-10-27 at 12:53 -0400, Jonathan S. Katz wrote:\n> > The patch I propose just layers on top of the existing functionality -- \n> > you could even argue that it's \"fixing a bug\" that we did not add the \n> > current \"map\" support for the case of \"clientcert=verify-full\" given we \n> > do introspect the certificate CN to see if it matches the SQL role name.\n> \n> Well, also to Tom's earlier point, though, this is a different sort of\n> mapping. Which \"map\" should we use if someone combines\n> clientcert=verify-full with an auth method which already uses a map\n> itself? Does the DBA want to map the auth name, the cert name, or both?\n\nMy understanding of the mapping system with pg_ident has always been\nthat it's a mapping from the 'authenticated user' to the 'user in PG'\nand the point is to check if that mapping is allowed but not to actually\nchange anything about who the ultimately logged in user is.\n\nThis is pretty clear and simple when the two are entirely disjoint- that\nis, with 'peer' or 'gssapi' or 'cert', the authenticated user will be\nwhatever the authentication system thinks it is- the Unix username for\npeer, the Kerberos principle for gssapi, the DN or CN for cert.\n\nIn all of the above cases, the username provided to us by the end user\nis the role they're trying to log in as and the mapping is just there to\ncheck if that's allowed based on the *authenticated username*. Perhaps\nnot surprisingly, 21.2 could use some improvement on this, but it's\ncertainly the case that the mapping is only there as a permission check\nand does not actually change who the user is logging into the system as.\nWhatever username is in the startup packet is the role that the user\nwill be logged in as if they're allowed to log in as that role.\n\nNow, when PG is involved in the authentication of the user, then I agree\nthat it gets more interesting. That is- the user wants to log in as\nuser u1, they have a certificate that has a DN of u1/user/domain, and we\nwant to verify that they know the password and present the right\ncertificate- but which password do they need to know?\n\nToday, there's really only one possible answer- the username in the\nstartup packet, because we don't have any concept of \"authenticate to PG\nas user u1 and then be logged in as user u2\". If we were to support a\nmapping for scram or md5, we'd really need the user to tell us both who\nto authenticate as and the user to log into PG as, and then we'd use\npg_ident.conf to ensure that such a mapping is allowed. If we wanted to\nimplement something along the lines of \"user authenticates as X but is\nlogged in as Y\" automatically, that would need to be something other\nthan pg_ident.conf, imv. I see that's been discussed a bit on the other\nthread I was explicitly trying to ignore and glad that it's more-or-less\ncoming to the same conclusion.\n\nWhere does that leave us with what Jonathan is suggesting though? For\nmy 2c, we shouldn't allow 'map=' to be used for scram or md5 because\nit'll just confuse users, until and unless we actually do the PGAUTHUSER\nthing and then we can allow 'map=' to check if that mapping is allowed\nand the actual SCRAM PW check is done against PGAUTHUSER and then the\nlogged in user is the user as specified in the startup packet, assuming\nthat mapping is allowed. For Jonathan's actual case though, we should\nadd a 'certmap' option instead and have that be explicitly for the case\nwhere it's scram w/ clientcert=verify-full and then we check the mapping\nof the DN/CN to the startup-packet username. There's no reason this\ncouldn't also work with a 'map' specified and PGAUTHUSER set and SCRAM\nused to verify against that at the same time.\n\n> The current usermap support is piecemeal and I'd like to see it\n> completed, but I think you may be painting yourself into a corner if\n> you fix it in this way. (From a quick look at the patch, I'm also\n> worried that this happens to work by accident, but that may just be\n> FUD.)\n\nI don't think it's an accident that it works, but a few comments and\na more explicit option for the user interface would be good. Admins\nwould be confused if 'map=xyz' was accepted for SCRAM but then didn't\nactually do anything.\n\n> > I think in the context of doing any new work, I'd step back and ask what \n> > problem is this solving? The main one I think of is an integration with \n> > a SSO system has a credential with an identifier that does not match \n> > it's credential in PostgreSQL? (That would be the case I was working on, \n> > though said case was borrowed from our docs). Are there other cases?\n> > \n> > That said, what would make it easier to manage it then? Maybe a lot of \n> > this is documenting and some expansion on what the pg_ident.conf file \n> > can do (per Andrew's suggestion). And maybe a new name for said file.\n> \n> I agree that the authorization system is due for a tuneup, for what\n> it's worth. Some of the comments from Magnus on my LDAP patch [1] kind\n> of hinted in that direction as well, I think, even if my approach is\n> rejected in the end.\n\nPerhaps not a surprise, but I continue to be against the idea of adding\nanything more to the insecure hack that is our LDAP auth method. We\nshould be moving away from that, not adding to it.\n\nThat this would also require a new connection option / envvar to tell us\nwho the user wants to authenticate to LDAP as doesn't exactly make me\nany more thrilled with it.\n\nJust my 2c though and I know others don't necessarily agree with me on\nthis point.\n\nThanks,\n\nStephen","msg_date":"Mon, 8 Nov 2021 15:32:40 -0500","msg_from":"Stephen Frost <sfrost@snowman.net>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"},{"msg_contents":"On Mon, 2021-11-08 at 15:32 -0500, Stephen Frost wrote:\r\n> Where does that leave us with what Jonathan is suggesting though? For\r\n> my 2c, we shouldn't allow 'map=' to be used for scram or md5 because\r\n> it'll just confuse users, until and unless we actually do the PGAUTHUSER\r\n> thing and then we can allow 'map=' to check if that mapping is allowed\r\n> and the actual SCRAM PW check is done against PGAUTHUSER and then the\r\n> logged in user is the user as specified in the startup packet, assuming\r\n> that mapping is allowed. For Jonathan's actual case though, we should\r\n> add a 'certmap' option instead and have that be explicitly for the case\r\n> where it's scram w/ clientcert=verify-full and then we check the mapping\r\n> of the DN/CN to the startup-packet username. There's no reason this\r\n> couldn't also work with a 'map' specified and PGAUTHUSER set and SCRAM\r\n> used to verify against that at the same time.\r\n\r\nAgreed.\r\n\r\n> Perhaps not a surprise, but I continue to be against the idea of adding\r\n> anything more to the insecure hack that is our LDAP auth method. We\r\n> should be moving away from that, not adding to it.\r\n\r\nParaphrasing you from earlier, the \"authenticate as one user and then\r\nlog in as another\" use case is the one I'm trying to expand. LDAP is\r\njust the auth method I happen to have present-day customer cases for.\r\n\r\n> That this would also require a new connection option / envvar to tell us\r\n> who the user wants to authenticate to LDAP as doesn't exactly make me\r\n> any more thrilled with it.\r\n\r\nForgetting the LDAP part for a moment, do you have another suggestion\r\nfor how we can separate the role name from the user name? The\r\nconnection string seemed to be the most straightforward.\r\n\r\n--Jacob\r\n","msg_date":"Tue, 30 Nov 2021 20:38:14 +0000","msg_from":"Jacob Champion <pchampion@vmware.com>","msg_from_op":false,"msg_subject":"Re: allowing \"map\" for password auth methods with\n clientcert=verify-full"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\r\\n\\r\\nSince PostgreSQL 12 (0516c61b756e39) we have allowed for the ability to \\r\\nset \\\"clientcert=verify-full\\\" against various HBA authentication methods. \\r\\nThis provides the ability to provide \\\"multi-factor authentication\\\" e.g. \\r\\na client must provide both a valid certificate with a CN (or DN) that \\r\\nmatches the user account, as well as a separate authentication challenge \\r\\n(e.g. a password).\\r\\n\\r\\nWith certificate-based authentication methods and other methods, we \\r\\nallow for users to specify a mapping in pg_ident, e.g. if one needs to \\r\\nperform a rewrite on the CN to match the username that is specified \\r\\nwithin PostgreSQL.\\r\\n\\r\\nIt seems logical that we should allow for something like:\\r\\n\\r\\n\\thostssl all all all scram-sha-256 clientcert=verify-full map=map\\r\\n\\r\\nso we can accept certificates that may have CNs that can be mapped to a \\r\\nPostgreSQL user name.\\r\\n\\r\\nCurrently we can't do this, as one will get the error:\\r\\n\\r\\n > authentication option \\\"map\\\" is only valid for authentication methods\\r\\n > ident, peer, gssapi, sspi, and cert\\r\\n\\r\\nI propose the below patch to add the currently supported password \\r\\nmethods, scram-sha-256 + md5 to allow for the \\\"map\\\" parameter to be \\r\\nused. I hesitate to add md5 given we're trying to phase it out, so open \\r\\nto debate there.\\r\\n\\r\\nWith my testing, this does work when you specify clientcert=verify-full: \\r\\nPostgreSQL will correctly map the certificate. If you do not have \\r\\nclientcert=verify-full, the mapping appears to do nothing.\\r\\n\\r\\nIf this seems acceptable/valid, I'll add the appropriate documentation \\r\\nand whatever else may be required.\\r\\n\\r\\nThanks,\\r\\n\\r\\nJonathan\",\n \"msg_date\": \"Tue, 26 Oct 2021 14:59:19 -0400\",\n \"msg_from\": \"\\\"Jonathan S. Katz\\\" <jkatz@postgresql.org>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"allowing \\\"map\\\" for password auth methods with clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"\\\"Jonathan S. Katz\\\" <jkatz@postgresql.org> writes:\\n> With certificate-based authentication methods and other methods, we \\n> allow for users to specify a mapping in pg_ident, e.g. if one needs to \\n> perform a rewrite on the CN to match the username that is specified \\n> within PostgreSQL.\\n\\n> It seems logical that we should allow for something like:\\n> \\thostssl all all all scram-sha-256 clientcert=verify-full map=map\\n> so we can accept certificates that may have CNs that can be mapped to a \\n> PostgreSQL user name.\\n\\nI think this is conflating two different things: a mapping from the\\nusername given in the startup packet, and a mapping from the TLS\\ncertificate CN. Using the same keyword and terminology for both\\nis going to lead to pain. I'm on board with the idea if we can\\ndisentangle that, though.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 15:26:08 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On 10/26/21 3:26 PM, Tom Lane wrote:\\r\\n> \\\"Jonathan S. Katz\\\" <jkatz@postgresql.org> writes:\\r\\n>> With certificate-based authentication methods and other methods, we\\r\\n>> allow for users to specify a mapping in pg_ident, e.g. if one needs to\\r\\n>> perform a rewrite on the CN to match the username that is specified\\r\\n>> within PostgreSQL.\\r\\n> \\r\\n>> It seems logical that we should allow for something like:\\r\\n>> \\thostssl all all all scram-sha-256 clientcert=verify-full map=map\\r\\n>> so we can accept certificates that may have CNs that can be mapped to a\\r\\n>> PostgreSQL user name.\\r\\n> \\r\\n> I think this is conflating two different things: a mapping from the\\r\\n> username given in the startup packet, and a mapping from the TLS\\r\\n> certificate CN. Using the same keyword and terminology for both\\r\\n> is going to lead to pain. I'm on board with the idea if we can\\r\\n> disentangle that, though.\\r\\n\\r\\nHm, don't we already have that already when using \\\"cert\\\" combined with \\r\\nthe \\\"map\\\" parameter? This is the main reason I \\\"stumbled\\\" upon this \\r\\nrecommendation.\\r\\n\\r\\nBased on what you say and if we're continuing with this functionality, \\r\\nwould solving the conflation be a matter of primarily documentation?\\r\\n\\r\\nThanks,\\r\\n\\r\\nJonathan\",\n \"msg_date\": \"Tue, 26 Oct 2021 16:04:01 -0400\",\n \"msg_from\": \"\\\"Jonathan S. Katz\\\" <jkatz@postgresql.org>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"\\\"Jonathan S. Katz\\\" <jkatz@postgresql.org> writes:\\n> On 10/26/21 3:26 PM, Tom Lane wrote:\\n>> I think this is conflating two different things: a mapping from the\\n>> username given in the startup packet, and a mapping from the TLS\\n>> certificate CN. Using the same keyword and terminology for both\\n>> is going to lead to pain. I'm on board with the idea if we can\\n>> disentangle that, though.\\n\\n> Hm, don't we already have that already when using \\\"cert\\\" combined with \\n> the \\\"map\\\" parameter? This is the main reason I \\\"stumbled\\\" upon this \\n> recommendation.\\n\\nI'm not exactly convinced that the existing design is any good.\\nI'm suggesting that we stop and think about it before propagating\\nit to a bunch of other use-cases.\\n\\nPer \\\"21.2. User Name Maps\\\", I think that the map parameter is supposed\\nto translate from the startup packet's user name to the SQL role name.\\nISTM that what is in the cert CN might be different from either\\n(particularly by perhaps having a domain name attached). So I'd be\\nhappier if there were a separate mapping available for the CN.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 18:16:34 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"\\nOn 10/26/21 18:16, Tom Lane wrote:\\n> \\\"Jonathan S. Katz\\\" <jkatz@postgresql.org> writes:\\n>> On 10/26/21 3:26 PM, Tom Lane wrote:\\n>>> I think this is conflating two different things: a mapping from the\\n>>> username given in the startup packet, and a mapping from the TLS\\n>>> certificate CN. Using the same keyword and terminology for both\\n>>> is going to lead to pain. I'm on board with the idea if we can\\n>>> disentangle that, though.\\n>> Hm, don't we already have that already when using \\\"cert\\\" combined with \\n>> the \\\"map\\\" parameter? This is the main reason I \\\"stumbled\\\" upon this \\n>> recommendation.\\n> I'm not exactly convinced that the existing design is any good.\\n> I'm suggesting that we stop and think about it before propagating\\n> it to a bunch of other use-cases.\\n>\\n> Per \\\"21.2. User Name Maps\\\", I think that the map parameter is supposed\\n> to translate from the startup packet's user name to the SQL role name.\\n> ISTM that what is in the cert CN might be different from either\\n> (particularly by perhaps having a domain name attached). So I'd be\\n> happier if there were a separate mapping available for the CN.\\n>\\n> \\t\\t\\t\\n\\n\\nPossibly slightly off topic, but\\n\\nThe cert+map pattern is very useful in conjunction with pgbouncer. Using\\nit with an auth query to get the password pgbouncer doesn't even need to\\nhave a list of users, and we in effect delegate authentication to\\npgbouncer.\\n\\nIt would be nice to have + and @ expansion for the usernames in the\\nident file, like there is for pg_hba.conf.\\n\\n\\ncheers\\n\\n\\nandrew\\n\\n--\\nAndrew Dunstan\\nEDB: https://www.enterprisedb.com\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 10:12:46 -0400\",\n \"msg_from\": \"Andrew Dunstan <andrew@dunslane.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On Tue, 2021-10-26 at 18:16 -0400, Tom Lane wrote:\\r\\n> Per \\\"21.2. User Name Maps\\\", I think that the map parameter is supposed\\r\\n> to translate from the startup packet's user name to the SQL role name.\\r\\n\\r\\nI may have misunderstood what you wrote, but IIUC the startup packet's\\r\\nuser name _is_ the SQL role name, even when using a map. The map is\\r\\njust determining whether or not the authenticated ID (pulled from a\\r\\ncertificate, or from Kerberos, or etc.) is authorized to use that role\\r\\nname. It's not a translation, because you can have a one-to-many user\\r\\nmapping (where me@example.com is allowed to log in as `me` or\\r\\n`postgres` or `admin` or...).\\r\\n\\r\\nPlease correct me if I've missed something -- I need to have it right\\r\\nin my head, given my other patches in this area...\\r\\n\\r\\n--Jacob\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 16:14:45 +0000\",\n \"msg_from\": \"Jacob Champion <pchampion@vmware.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-10-27 at 10:12 -0400, Andrew Dunstan wrote:\\r\\n> Possibly slightly off topic, but\\r\\n> \\r\\n> The cert+map pattern is very useful in conjunction with pgbouncer. Using\\r\\n> it with an auth query to get the password pgbouncer doesn't even need to\\r\\n> have a list of users, and we in effect delegate authentication to\\r\\n> pgbouncer.\\r\\n> \\r\\n> It would be nice to have + and @ expansion for the usernames in the\\r\\n> ident file, like there is for pg_hba.conf.\\r\\n\\r\\n(Probably is off-topic :D but +1 to the concept. Combined with LDAP\\r\\nmapping that could make some of the ad-hoc LDAP-to-Postgres sync\\r\\nscripts a lot simpler.)\\r\\n\\r\\n--Jacob\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 16:49:21 +0000\",\n \"msg_from\": \"Jacob Champion <pchampion@vmware.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On 10/27/21 12:14 PM, Jacob Champion wrote:\\r\\n> On Tue, 2021-10-26 at 18:16 -0400, Tom Lane wrote:\\r\\n>> Per \\\"21.2. User Name Maps\\\", I think that the map parameter is supposed\\r\\n>> to translate from the startup packet's user name to the SQL role name.\\r\\n> \\r\\n> I may have misunderstood what you wrote, but IIUC the startup packet's\\r\\n> user name _is_ the SQL role name, even when using a map. The map is\\r\\n> just determining whether or not the authenticated ID (pulled from a\\r\\n> certificate, or from Kerberos, or etc.) is authorized to use that role\\r\\n> name. It's not a translation, because you can have a one-to-many user\\r\\n> mapping (where me@example.com is allowed to log in as `me` or\\r\\n> `postgres` or `admin` or...).\\r\\n> \\r\\n> Please correct me if I've missed something -- I need to have it right\\r\\n> in my head, given my other patches in this area...\\r\\n\\r\\nTo Tom's earlier point, I understand why we may want to pause and think \\r\\nabout this.\\r\\n\\r\\nI don't know the whole history of the \\\"pg_ident.conf\\\" file, but judging \\r\\nby the name, my guess is that the mapping functionality started with the \\r\\n\\\"ident\\\" authentication support, and then it was used for other auth \\r\\ntypes that could benefit from mapping (cert/gssapi etc.). The \\r\\ndocumentation referenced also skews towards describing what the original \\r\\nfunctionality for ident does.\\r\\n\\r\\nThat said, the existing functionality does match what Jacob is \\r\\ndescribing and what my own understanding is.\\r\\n\\r\\nThe patch I propose just layers on top of the existing functionality -- \\r\\n you could even argue that it's \\\"fixing a bug\\\" that we did not add the \\r\\ncurrent \\\"map\\\" support for the case of \\\"clientcert=verify-full\\\" given we \\r\\ndo introspect the certificate CN to see if it matches the SQL role name.\\r\\n\\r\\nIn terms of other user mapping functionality, we have ad hoc support for \\r\\nFDWs when trying to map to a user in a different server:\\r\\n\\r\\nhttps://www.postgresql.org/docs/current/sql-createusermapping.html\\r\\n\\r\\nI'm unsure if there is anything we'd want to leverage here, as the \\r\\noverall goal of this is to provide the ability to establish a connection \\r\\nwith a remote server.\\r\\n\\r\\nI think in the context of doing any new work, I'd step back and ask what \\r\\nproblem is this solving? The main one I think of is an integration with \\r\\na SSO system has a credential with an identifier that does not match \\r\\nit's credential in PostgreSQL? (That would be the case I was working on, \\r\\nthough said case was borrowed from our docs). Are there other cases?\\r\\n\\r\\nThat said, what would make it easier to manage it then? Maybe a lot of \\r\\nthis is documenting and some expansion on what the pg_ident.conf file \\r\\ncan do (per Andrew's suggestion). And maybe a new name for said file.\\r\\n\\r\\nI don't know if we would want to bring any of this into the catalog or \\r\\nnot -- but perhaps there may be some advantages to that from an \\r\\nadministration standpoint.\\r\\n\\r\\nAnyway, those are my initial thoughts on the challenge to think a bit \\r\\nmore deeply about this. I'd still suggest considering the patch I \\r\\npropose as an \\\"immediate fix\\\" for existing versions as, at least to \\r\\nmyself, I can argue it's a bug. We can then do some more work to make \\r\\nthe overall system a bit easier/clearer to use and maintain.\\r\\n\\r\\nThanks,\\r\\n\\r\\nJonathan\",\n \"msg_date\": \"Wed, 27 Oct 2021 12:53:44 -0400\",\n \"msg_from\": \"\\\"Jonathan S. Katz\\\" <jkatz@postgresql.org>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On Wed, 2021-10-27 at 12:53 -0400, Jonathan S. Katz wrote:\\r\\n> The patch I propose just layers on top of the existing functionality -- \\r\\n> you could even argue that it's \\\"fixing a bug\\\" that we did not add the \\r\\n> current \\\"map\\\" support for the case of \\\"clientcert=verify-full\\\" given we \\r\\n> do introspect the certificate CN to see if it matches the SQL role name.\\r\\n\\r\\nWell, also to Tom's earlier point, though, this is a different sort of\\r\\nmapping. Which \\\"map\\\" should we use if someone combines\\r\\nclientcert=verify-full with an auth method which already uses a map\\r\\nitself? Does the DBA want to map the auth name, the cert name, or both?\\r\\n\\r\\nThe current usermap support is piecemeal and I'd like to see it\\r\\ncompleted, but I think you may be painting yourself into a corner if\\r\\nyou fix it in this way. (From a quick look at the patch, I'm also\\r\\nworried that this happens to work by accident, but that may just be\\r\\nFUD.)\\r\\n\\r\\n> I think in the context of doing any new work, I'd step back and ask what \\r\\n> problem is this solving? The main one I think of is an integration with \\r\\n> a SSO system has a credential with an identifier that does not match \\r\\n> it's credential in PostgreSQL? (That would be the case I was working on, \\r\\n> though said case was borrowed from our docs). Are there other cases?\\r\\n> \\r\\n> That said, what would make it easier to manage it then? Maybe a lot of \\r\\n> this is documenting and some expansion on what the pg_ident.conf file \\r\\n> can do (per Andrew's suggestion). And maybe a new name for said file.\\r\\n\\r\\nI agree that the authorization system is due for a tuneup, for what\\r\\nit's worth. Some of the comments from Magnus on my LDAP patch [1] kind\\r\\nof hinted in that direction as well, I think, even if my approach is\\r\\nrejected in the end.\\r\\n\\r\\n--Jacob\\r\\n\\r\\n[1] https://www.postgresql.org/message-id/flat/1a61806047c536e7528b943d0cfe12608118ca31.camel@vmware.com\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 17:37:49 +0000\",\n \"msg_from\": \"Jacob Champion <pchampion@vmware.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"Greetings,\\n\\n* Jacob Champion (pchampion@vmware.com) wrote:\\n> On Wed, 2021-10-27 at 12:53 -0400, Jonathan S. Katz wrote:\\n> > The patch I propose just layers on top of the existing functionality -- \\n> > you could even argue that it's \\\"fixing a bug\\\" that we did not add the \\n> > current \\\"map\\\" support for the case of \\\"clientcert=verify-full\\\" given we \\n> > do introspect the certificate CN to see if it matches the SQL role name.\\n> \\n> Well, also to Tom's earlier point, though, this is a different sort of\\n> mapping. Which \\\"map\\\" should we use if someone combines\\n> clientcert=verify-full with an auth method which already uses a map\\n> itself? Does the DBA want to map the auth name, the cert name, or both?\\n\\nMy understanding of the mapping system with pg_ident has always been\\nthat it's a mapping from the 'authenticated user' to the 'user in PG'\\nand the point is to check if that mapping is allowed but not to actually\\nchange anything about who the ultimately logged in user is.\\n\\nThis is pretty clear and simple when the two are entirely disjoint- that\\nis, with 'peer' or 'gssapi' or 'cert', the authenticated user will be\\nwhatever the authentication system thinks it is- the Unix username for\\npeer, the Kerberos principle for gssapi, the DN or CN for cert.\\n\\nIn all of the above cases, the username provided to us by the end user\\nis the role they're trying to log in as and the mapping is just there to\\ncheck if that's allowed based on the *authenticated username*. Perhaps\\nnot surprisingly, 21.2 could use some improvement on this, but it's\\ncertainly the case that the mapping is only there as a permission check\\nand does not actually change who the user is logging into the system as.\\nWhatever username is in the startup packet is the role that the user\\nwill be logged in as if they're allowed to log in as that role.\\n\\nNow, when PG is involved in the authentication of the user, then I agree\\nthat it gets more interesting. That is- the user wants to log in as\\nuser u1, they have a certificate that has a DN of u1/user/domain, and we\\nwant to verify that they know the password and present the right\\ncertificate- but which password do they need to know?\\n\\nToday, there's really only one possible answer- the username in the\\nstartup packet, because we don't have any concept of \\\"authenticate to PG\\nas user u1 and then be logged in as user u2\\\". If we were to support a\\nmapping for scram or md5, we'd really need the user to tell us both who\\nto authenticate as and the user to log into PG as, and then we'd use\\npg_ident.conf to ensure that such a mapping is allowed. If we wanted to\\nimplement something along the lines of \\\"user authenticates as X but is\\nlogged in as Y\\\" automatically, that would need to be something other\\nthan pg_ident.conf, imv. I see that's been discussed a bit on the other\\nthread I was explicitly trying to ignore and glad that it's more-or-less\\ncoming to the same conclusion.\\n\\nWhere does that leave us with what Jonathan is suggesting though? For\\nmy 2c, we shouldn't allow 'map=' to be used for scram or md5 because\\nit'll just confuse users, until and unless we actually do the PGAUTHUSER\\nthing and then we can allow 'map=' to check if that mapping is allowed\\nand the actual SCRAM PW check is done against PGAUTHUSER and then the\\nlogged in user is the user as specified in the startup packet, assuming\\nthat mapping is allowed. For Jonathan's actual case though, we should\\nadd a 'certmap' option instead and have that be explicitly for the case\\nwhere it's scram w/ clientcert=verify-full and then we check the mapping\\nof the DN/CN to the startup-packet username. There's no reason this\\ncouldn't also work with a 'map' specified and PGAUTHUSER set and SCRAM\\nused to verify against that at the same time.\\n\\n> The current usermap support is piecemeal and I'd like to see it\\n> completed, but I think you may be painting yourself into a corner if\\n> you fix it in this way. (From a quick look at the patch, I'm also\\n> worried that this happens to work by accident, but that may just be\\n> FUD.)\\n\\nI don't think it's an accident that it works, but a few comments and\\na more explicit option for the user interface would be good. Admins\\nwould be confused if 'map=xyz' was accepted for SCRAM but then didn't\\nactually do anything.\\n\\n> > I think in the context of doing any new work, I'd step back and ask what \\n> > problem is this solving? The main one I think of is an integration with \\n> > a SSO system has a credential with an identifier that does not match \\n> > it's credential in PostgreSQL? (That would be the case I was working on, \\n> > though said case was borrowed from our docs). Are there other cases?\\n> > \\n> > That said, what would make it easier to manage it then? Maybe a lot of \\n> > this is documenting and some expansion on what the pg_ident.conf file \\n> > can do (per Andrew's suggestion). And maybe a new name for said file.\\n> \\n> I agree that the authorization system is due for a tuneup, for what\\n> it's worth. Some of the comments from Magnus on my LDAP patch [1] kind\\n> of hinted in that direction as well, I think, even if my approach is\\n> rejected in the end.\\n\\nPerhaps not a surprise, but I continue to be against the idea of adding\\nanything more to the insecure hack that is our LDAP auth method. We\\nshould be moving away from that, not adding to it.\\n\\nThat this would also require a new connection option / envvar to tell us\\nwho the user wants to authenticate to LDAP as doesn't exactly make me\\nany more thrilled with it.\\n\\nJust my 2c though and I know others don't necessarily agree with me on\\nthis point.\\n\\nThanks,\\n\\nStephen\",\n \"msg_date\": \"Mon, 8 Nov 2021 15:32:40 -0500\",\n \"msg_from\": \"Stephen Frost <sfrost@snowman.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n },\n {\n \"msg_contents\": \"On Mon, 2021-11-08 at 15:32 -0500, Stephen Frost wrote:\\r\\n> Where does that leave us with what Jonathan is suggesting though? For\\r\\n> my 2c, we shouldn't allow 'map=' to be used for scram or md5 because\\r\\n> it'll just confuse users, until and unless we actually do the PGAUTHUSER\\r\\n> thing and then we can allow 'map=' to check if that mapping is allowed\\r\\n> and the actual SCRAM PW check is done against PGAUTHUSER and then the\\r\\n> logged in user is the user as specified in the startup packet, assuming\\r\\n> that mapping is allowed. For Jonathan's actual case though, we should\\r\\n> add a 'certmap' option instead and have that be explicitly for the case\\r\\n> where it's scram w/ clientcert=verify-full and then we check the mapping\\r\\n> of the DN/CN to the startup-packet username. There's no reason this\\r\\n> couldn't also work with a 'map' specified and PGAUTHUSER set and SCRAM\\r\\n> used to verify against that at the same time.\\r\\n\\r\\nAgreed.\\r\\n\\r\\n> Perhaps not a surprise, but I continue to be against the idea of adding\\r\\n> anything more to the insecure hack that is our LDAP auth method. We\\r\\n> should be moving away from that, not adding to it.\\r\\n\\r\\nParaphrasing you from earlier, the \\\"authenticate as one user and then\\r\\nlog in as another\\\" use case is the one I'm trying to expand. LDAP is\\r\\njust the auth method I happen to have present-day customer cases for.\\r\\n\\r\\n> That this would also require a new connection option / envvar to tell us\\r\\n> who the user wants to authenticate to LDAP as doesn't exactly make me\\r\\n> any more thrilled with it.\\r\\n\\r\\nForgetting the LDAP part for a moment, do you have another suggestion\\r\\nfor how we can separate the role name from the user name? The\\r\\nconnection string seemed to be the most straightforward.\\r\\n\\r\\n--Jacob\\r\\n\",\n \"msg_date\": \"Tue, 30 Nov 2021 20:38:14 +0000\",\n \"msg_from\": \"Jacob Champion <pchampion@vmware.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: allowing \\\"map\\\" for password auth methods with\\n clientcert=verify-full\"\n }\n]","isConversational":false}}},{"rowIdx":52995,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"[PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in fmtint\n\nfmtint() turns an integer into a string for a given base, and to do this\nit does a divide/modulo operation iteratively.\nThe only possible base values are 8, 10 and 16\n\nOn just about any CPU, divides are a pretty expensive operation, generally\n10x to 20x or more expensive than adds or multiplies.\n\nBy special casing the base values, the compiler (gcc or other) can (and will)\nreplace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\nfor base 8 and 16, yielding a lot faster code.\n\nI considered a switch statement, but since base 10 is the most common by far,\nI implemented it as a series of if/else statements with a likely() marking the 10 case.\n\nEven though this only shows up in the database creation phase of pgbench and not so much\nduring the normal run time, the optimization is simple and high value enough that\nin my opinion it's worth doing\n\n\n\n\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\nindex 7c21429369..547a59d4a0 100644\n--- a/src/port/snprintf.c\n+++ b/src/port/snprintf.c\n@@ -1076,11 +1076,31 @@ fmtint(long long value, char type, int forcesign, int leftjust,\n \telse\n \t{\n \t\t/* make integer string */\n-\t\tdo\n-\t\t{\n-\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n-\t\t\tuvalue = uvalue / base;\n-\t\t} while (uvalue);\n+\n+\t\t/*\n+\t\t * Special case each of the possible base values (8, 10, 16) to avoid an\n+\t\t * expensive divide operation\n+\t\t * (the compiler will use a multiply, shift or boolean ops for this)\n+\t\t */\n+\t\tif (likely(base == 10)) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\n+\t\t\t\tuvalue = uvalue / 10;\n+\t\t\t} while (uvalue);\n+\t\t} else if (base == 16) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 16];\n+\t\t\t\tuvalue = uvalue / 16;\n+\t\t\t} while (uvalue);\n+\t\t} else if (base == 8) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 8];\n+\t\t\t\tuvalue = uvalue / 8;\n+\t\t\t} while (uvalue);\n+\t\t}\n \t}\n\n \tzeropad = Max(0, precision - vallen);\n\n\n","msg_date":"Tue, 26 Oct 2021 13:58:17 -0700","msg_from":"Arjan van de Ven <arjan@linux.intel.com>","msg_from_op":true,"msg_subject":"[PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in\n fmtint"},{"msg_contents":"\nOn Wed, 27 Oct 2021 at 04:58, Arjan van de Ven <arjan@linux.intel.com> wrote:\n> [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in fmtint\n>\n> fmtint() turns an integer into a string for a given base, and to do this\n> it does a divide/modulo operation iteratively.\n> The only possible base values are 8, 10 and 16\n>\n> On just about any CPU, divides are a pretty expensive operation, generally\n> 10x to 20x or more expensive than adds or multiplies.\n>\n> By special casing the base values, the compiler (gcc or other) can (and will)\n> replace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\n> for base 8 and 16, yielding a lot faster code.\n>\n> I considered a switch statement, but since base 10 is the most common by far,\n> I implemented it as a series of if/else statements with a likely() marking the 10 case.\n>\n> Even though this only shows up in the database creation phase of pgbench and not so much\n> during the normal run time, the optimization is simple and high value enough that\n> in my opinion it's worth doing\n>\n>\n\n\n+\t\tif (likely(base == 10)) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\n+\t\t\t\tuvalue = uvalue / 10;\n+\t\t\t} while (uvalue);\n+\t\t} else if (base == 16) {\n\nWhy do we need likely() for base=10, however, base=16 and base=8 don't need?\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.\n\n\n","msg_date":"Wed, 27 Oct 2021 09:36:35 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10\n case in fmtint"},{"msg_contents":"Japin Li <japinli@hotmail.com> writes:\n> Why do we need likely() for base=10, however, base=16 and base=8 don't need?\n\nYeah, I was a little unconvinced about that too. I concur with writing\nit as an if/else chain instead of a switch, but I'm not sure that likely()\nadds anything to that.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Tue, 26 Oct 2021 21:39:54 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"},{"msg_contents":"On 10/26/2021 6:39 PM, Tom Lane wrote:\n> Japin Li <japinli@hotmail.com> writes:\n>> Why do we need likely() for base=10, however, base=16 and base=8 don't need?\n> \n> Yeah, I was a little unconvinced about that too. I concur with writing\n> it as an if/else chain instead of a switch, but I'm not sure that likely()\n> adds anything to that.\n\nfair enough:\n\n[PATCH v3] src/port/snprintf.c: Optimize the division away in fmtint\n\nfmtint() turns an integer into a string for a given base, and to do this\nit does a divide/modulo operation iteratively.\nThe only possible base values are 8, 10 and 16\n\nOn just about any CPU, generic divides are a pretty expensive operation, generally\n10x to 20x or more expensive than adds or multiplies.\n\nBy special casing the base values, the compiler (gcc or other) can (and will)\nreplace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\nfor base 8 and 16, yielding a lot faster code.\n\nI considered a switch statement, but since base 10 is the most common by far,\nI implemented it as a series of if/else statements for simplicity.\n\nEven though this only shows up in the database creation phase of pgbench and not so much\nduring the normal run time, the optimization is simple and high value enough that\nin my opinion it's worth doing\n\n\n\n\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\nindex 7c21429369..547a59d4a0 100644\n--- a/src/port/snprintf.c\n+++ b/src/port/snprintf.c\n@@ -1076,11 +1076,31 @@ fmtint(long long value, char type, int forcesign, int leftjust,\n \telse\n \t{\n \t\t/* make integer string */\n-\t\tdo\n-\t\t{\n-\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\n-\t\t\tuvalue = uvalue / base;\n-\t\t} while (uvalue);\n+\n+\t\t/*\n+\t\t * Special case each of the possible base values (8, 10, 16) to avoid an\n+\t\t * expensive divide operation\n+\t\t * (the compiler will use a multiply, shift or boolean ops for this)\n+\t\t */\n+\t\tif (base == 10) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\n+\t\t\t\tuvalue = uvalue / 10;\n+\t\t\t} while (uvalue);\n+\t\t} else if (base == 16) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 16];\n+\t\t\t\tuvalue = uvalue / 16;\n+\t\t\t} while (uvalue);\n+\t\t} else if (base == 8) {\n+\t\t\tdo\n+\t\t\t{\n+\t\t\t\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 8];\n+\t\t\t\tuvalue = uvalue / 8;\n+\t\t\t} while (uvalue);\n+\t\t}\n \t}\n\n \tzeropad = Max(0, precision - vallen);\n\n\n\n","msg_date":"Wed, 27 Oct 2021 15:18:13 -0700","msg_from":"Arjan van de Ven <arjan@linux.intel.com>","msg_from_op":true,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"},{"msg_contents":"On 10/27/21 18:18, Arjan van de Ven wrote:\n> + /*\n> + * Special case each of the possible base values (8, 10, 16) to\n> avoid an\n> + * expensive divide operation\n> + * (the compiler will use a multiply, shift or boolean ops for this)\n> + */\n\n\nWas 'boolean' the intended word there? To me it is distinct from 'bitwise'.\n\nRegards,\n-Chap\n\n\n","msg_date":"Wed, 27 Oct 2021 19:50:45 -0400","msg_from":"Chapman Flack <chap@anastigmatix.net>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"},{"msg_contents":"Chapman Flack <chap@anastigmatix.net> writes:\n> On 10/27/21 18:18, Arjan van de Ven wrote:\n>> + /*\n>> + * Special case each of the possible base values (8, 10, 16) to\n>> avoid an\n>> + * expensive divide operation\n>> + * (the compiler will use a multiply, shift or boolean ops for this)\n>> + */\n\n> Was 'boolean' the intended word there? To me it is distinct from 'bitwise'.\n\nI think the comment is overly specific anyway. We should just say\n\"division by a constant is faster than general-purpose division\".\nOnly compiler geeks will care about the details, and they probably\nknow them already.\n\nPersonally, I failed to measure any speedup at all on pgbench, either\nin the init phase or regular transactions; whatever difference there\nmay be is below the noise level. However, I wrote a simple C function\nwith a tight loop around snprintf(), and that showed about a 2X\nimprovement, so there is some win here.\n\nI went ahead and pushed it with a rewritten comment.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 28 Oct 2021 13:46:49 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"},{"msg_contents":"Hi,\n\nOn 2021-10-28 13:46:49 -0400, Tom Lane wrote:\n> Personally, I failed to measure any speedup at all on pgbench, either\n> in the init phase or regular transactions; whatever difference there\n> may be is below the noise level. However, I wrote a simple C function\n> with a tight loop around snprintf(), and that showed about a 2X\n> improvement, so there is some win here.\n\nOdd - at least with an earlier patch I saw optimized pgbench initialization go\ndown by ~25%.\n\n\n> I went ahead and pushed it with a rewritten comment.\n\nImo the code now is a bit odd, because we first switch (type) setting base,\nand then separately have branches for the different bases.\n\nGreetings,\n\nAndres Freund\n\n\n","msg_date":"Thu, 28 Oct 2021 13:27:49 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"},{"msg_contents":"Andres Freund <andres@anarazel.de> writes:\n> Imo the code now is a bit odd, because we first switch (type) setting base,\n> and then separately have branches for the different bases.\n\nIt'd be hard to merge, I think, given that the cases in the switch\ndon't line up one-for-one with the different bases. You could\nprobably do something involving falling through between different\ncases, but I think that that would be a lot harder to read;\nand I'm still of the opinion that micro-optimizing this code\nis probably a waste of effort for our usage.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 28 Oct 2021 16:34:06 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\n in fmtint"}],"string":"[\n {\n \"msg_contents\": \"[PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in fmtint\\n\\nfmtint() turns an integer into a string for a given base, and to do this\\nit does a divide/modulo operation iteratively.\\nThe only possible base values are 8, 10 and 16\\n\\nOn just about any CPU, divides are a pretty expensive operation, generally\\n10x to 20x or more expensive than adds or multiplies.\\n\\nBy special casing the base values, the compiler (gcc or other) can (and will)\\nreplace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\\nfor base 8 and 16, yielding a lot faster code.\\n\\nI considered a switch statement, but since base 10 is the most common by far,\\nI implemented it as a series of if/else statements with a likely() marking the 10 case.\\n\\nEven though this only shows up in the database creation phase of pgbench and not so much\\nduring the normal run time, the optimization is simple and high value enough that\\nin my opinion it's worth doing\\n\\n\\n\\n\\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\\nindex 7c21429369..547a59d4a0 100644\\n--- a/src/port/snprintf.c\\n+++ b/src/port/snprintf.c\\n@@ -1076,11 +1076,31 @@ fmtint(long long value, char type, int forcesign, int leftjust,\\n \\telse\\n \\t{\\n \\t\\t/* make integer string */\\n-\\t\\tdo\\n-\\t\\t{\\n-\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n-\\t\\t\\tuvalue = uvalue / base;\\n-\\t\\t} while (uvalue);\\n+\\n+\\t\\t/*\\n+\\t\\t * Special case each of the possible base values (8, 10, 16) to avoid an\\n+\\t\\t * expensive divide operation\\n+\\t\\t * (the compiler will use a multiply, shift or boolean ops for this)\\n+\\t\\t */\\n+\\t\\tif (likely(base == 10)) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\\n+\\t\\t\\t\\tuvalue = uvalue / 10;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else if (base == 16) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 16];\\n+\\t\\t\\t\\tuvalue = uvalue / 16;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else if (base == 8) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 8];\\n+\\t\\t\\t\\tuvalue = uvalue / 8;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t}\\n \\t}\\n\\n \\tzeropad = Max(0, precision - vallen);\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 13:58:17 -0700\",\n \"msg_from\": \"Arjan van de Ven <arjan@linux.intel.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"[PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in\\n fmtint\"\n },\n {\n \"msg_contents\": \"\\nOn Wed, 27 Oct 2021 at 04:58, Arjan van de Ven <arjan@linux.intel.com> wrote:\\n> [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in fmtint\\n>\\n> fmtint() turns an integer into a string for a given base, and to do this\\n> it does a divide/modulo operation iteratively.\\n> The only possible base values are 8, 10 and 16\\n>\\n> On just about any CPU, divides are a pretty expensive operation, generally\\n> 10x to 20x or more expensive than adds or multiplies.\\n>\\n> By special casing the base values, the compiler (gcc or other) can (and will)\\n> replace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\\n> for base 8 and 16, yielding a lot faster code.\\n>\\n> I considered a switch statement, but since base 10 is the most common by far,\\n> I implemented it as a series of if/else statements with a likely() marking the 10 case.\\n>\\n> Even though this only shows up in the database creation phase of pgbench and not so much\\n> during the normal run time, the optimization is simple and high value enough that\\n> in my opinion it's worth doing\\n>\\n>\\n\\n\\n+\\t\\tif (likely(base == 10)) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\\n+\\t\\t\\t\\tuvalue = uvalue / 10;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else if (base == 16) {\\n\\nWhy do we need likely() for base=10, however, base=16 and base=8 don't need?\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 09:36:35 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10\\n case in fmtint\"\n },\n {\n \"msg_contents\": \"Japin Li <japinli@hotmail.com> writes:\\n> Why do we need likely() for base=10, however, base=16 and base=8 don't need?\\n\\nYeah, I was a little unconvinced about that too. I concur with writing\\nit as an if/else chain instead of a switch, but I'm not sure that likely()\\nadds anything to that.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 21:39:54 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n },\n {\n \"msg_contents\": \"On 10/26/2021 6:39 PM, Tom Lane wrote:\\n> Japin Li <japinli@hotmail.com> writes:\\n>> Why do we need likely() for base=10, however, base=16 and base=8 don't need?\\n> \\n> Yeah, I was a little unconvinced about that too. I concur with writing\\n> it as an if/else chain instead of a switch, but I'm not sure that likely()\\n> adds anything to that.\\n\\nfair enough:\\n\\n[PATCH v3] src/port/snprintf.c: Optimize the division away in fmtint\\n\\nfmtint() turns an integer into a string for a given base, and to do this\\nit does a divide/modulo operation iteratively.\\nThe only possible base values are 8, 10 and 16\\n\\nOn just about any CPU, generic divides are a pretty expensive operation, generally\\n10x to 20x or more expensive than adds or multiplies.\\n\\nBy special casing the base values, the compiler (gcc or other) can (and will)\\nreplace the divide by a multiply with 0xcccccccccccccccd (for base 10) or bitops\\nfor base 8 and 16, yielding a lot faster code.\\n\\nI considered a switch statement, but since base 10 is the most common by far,\\nI implemented it as a series of if/else statements for simplicity.\\n\\nEven though this only shows up in the database creation phase of pgbench and not so much\\nduring the normal run time, the optimization is simple and high value enough that\\nin my opinion it's worth doing\\n\\n\\n\\n\\ndiff --git a/src/port/snprintf.c b/src/port/snprintf.c\\nindex 7c21429369..547a59d4a0 100644\\n--- a/src/port/snprintf.c\\n+++ b/src/port/snprintf.c\\n@@ -1076,11 +1076,31 @@ fmtint(long long value, char type, int forcesign, int leftjust,\\n \\telse\\n \\t{\\n \\t\\t/* make integer string */\\n-\\t\\tdo\\n-\\t\\t{\\n-\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % base];\\n-\\t\\t\\tuvalue = uvalue / base;\\n-\\t\\t} while (uvalue);\\n+\\n+\\t\\t/*\\n+\\t\\t * Special case each of the possible base values (8, 10, 16) to avoid an\\n+\\t\\t * expensive divide operation\\n+\\t\\t * (the compiler will use a multiply, shift or boolean ops for this)\\n+\\t\\t */\\n+\\t\\tif (base == 10) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 10];\\n+\\t\\t\\t\\tuvalue = uvalue / 10;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else if (base == 16) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 16];\\n+\\t\\t\\t\\tuvalue = uvalue / 16;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t} else if (base == 8) {\\n+\\t\\t\\tdo\\n+\\t\\t\\t{\\n+\\t\\t\\t\\tconvert[sizeof(convert) - (++vallen)] = cvt[uvalue % 8];\\n+\\t\\t\\t\\tuvalue = uvalue / 8;\\n+\\t\\t\\t} while (uvalue);\\n+\\t\\t}\\n \\t}\\n\\n \\tzeropad = Max(0, precision - vallen);\\n\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 15:18:13 -0700\",\n \"msg_from\": \"Arjan van de Ven <arjan@linux.intel.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n },\n {\n \"msg_contents\": \"On 10/27/21 18:18, Arjan van de Ven wrote:\\n> + /*\\n> + * Special case each of the possible base values (8, 10, 16) to\\n> avoid an\\n> + * expensive divide operation\\n> + * (the compiler will use a multiply, shift or boolean ops for this)\\n> + */\\n\\n\\nWas 'boolean' the intended word there? To me it is distinct from 'bitwise'.\\n\\nRegards,\\n-Chap\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 19:50:45 -0400\",\n \"msg_from\": \"Chapman Flack <chap@anastigmatix.net>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n },\n {\n \"msg_contents\": \"Chapman Flack <chap@anastigmatix.net> writes:\\n> On 10/27/21 18:18, Arjan van de Ven wrote:\\n>> + /*\\n>> + * Special case each of the possible base values (8, 10, 16) to\\n>> avoid an\\n>> + * expensive divide operation\\n>> + * (the compiler will use a multiply, shift or boolean ops for this)\\n>> + */\\n\\n> Was 'boolean' the intended word there? To me it is distinct from 'bitwise'.\\n\\nI think the comment is overly specific anyway. We should just say\\n\\\"division by a constant is faster than general-purpose division\\\".\\nOnly compiler geeks will care about the details, and they probably\\nknow them already.\\n\\nPersonally, I failed to measure any speedup at all on pgbench, either\\nin the init phase or regular transactions; whatever difference there\\nmay be is below the noise level. However, I wrote a simple C function\\nwith a tight loop around snprintf(), and that showed about a 2X\\nimprovement, so there is some win here.\\n\\nI went ahead and pushed it with a rewritten comment.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 13:46:49 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2021-10-28 13:46:49 -0400, Tom Lane wrote:\\n> Personally, I failed to measure any speedup at all on pgbench, either\\n> in the init phase or regular transactions; whatever difference there\\n> may be is below the noise level. However, I wrote a simple C function\\n> with a tight loop around snprintf(), and that showed about a 2X\\n> improvement, so there is some win here.\\n\\nOdd - at least with an earlier patch I saw optimized pgbench initialization go\\ndown by ~25%.\\n\\n\\n> I went ahead and pushed it with a rewritten comment.\\n\\nImo the code now is a bit odd, because we first switch (type) setting base,\\nand then separately have branches for the different bases.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 13:27:49 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n },\n {\n \"msg_contents\": \"Andres Freund <andres@anarazel.de> writes:\\n> Imo the code now is a bit odd, because we first switch (type) setting base,\\n> and then separately have branches for the different bases.\\n\\nIt'd be hard to merge, I think, given that the cases in the switch\\ndon't line up one-for-one with the different bases. You could\\nprobably do something involving falling through between different\\ncases, but I think that that would be a lot harder to read;\\nand I'm still of the opinion that micro-optimizing this code\\nis probably a waste of effort for our usage.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 16:34:06 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH v2] src/port/snprintf.c: Optimize the common base=10 case\\n in fmtint\"\n }\n]","isConversational":false}}},{"rowIdx":52996,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Generally if a role is granted membership to another role with NOINHERIT\nthey must use SET ROLE to access the privileges of that role, however\nwith predefined roles the membership and privilege is conflated, as\ndemonstrated by:\n\nCREATE ROLE readrole;\nCREATE ROLE role2 NOINHERIT;\nCREATE ROLE brindle LOGIN;\n\nGRANT role2 TO brindle;\nCREATE TABLE foo(i INT);\nGRANT readrole TO role2;\nGRANT ALL ON TABLE foo TO readrole;\n\nGRANT pg_read_all_stats,pg_read_all_settings,pg_read_server_files,pg_write_server_files,pg_execute_server_program TO role2;\n\nLog in as brindle:\n\npostgres=> select current_user;\n current_user\n--------------\n brindle\n(1 row)\n\npostgres=> SELECT * FROM foo;\nERROR: permission denied for table foo\n\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\n query\n----------------------------------------------\n\n SELECT DISTINCT query FROM pg_stat_activity;\n(2 rows)\n\npostgres=> SET ROLE readrole;\nSET\npostgres=> SELECT * FROM foo;\n i\n---\n(0 rows)\n\nAfter this patch:\n\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\n query\n--------------------------\n <insufficient privilege>\n(1 row)\n\npostgres=> SET ROLE pg_read_all_stats;\nSET\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\n query\n----------------------------------------------\n\n SELECT DISTINCT query FROM pg_stat_activity;\n(2 rows)\n\npostgres=> SHOW config_file;\nERROR: must be superuser or have privileges of pg_read_all_settings to examine \"config_file\"\npostgres=> SET ROLE pg_read_all_settings;\nSET\npostgres=> SHOW config_file;\n config_file\n-----------------------------------\n /var/lib/pgsql/15/postgresql.conf\n(1 row)\n\nWith inheritance it works as expected:\n\nALTER ROLE role2 INHERIT;\n\npostgres=> SELECT current_user;\n current_user\n--------------\n brindle\n(1 row)\n\npostgres=> SHOW config_file;\n config_file\n-----------------------------------\n /var/lib/pgsql/15/postgresql.conf\n(1 row)\n\nSigned-off-by: Joshua Brindle <joshua.brindle@crunchydata.com>\n---\n src/backend/commands/copy.c | 12 ++++++------\n src/backend/replication/walreceiver.c | 8 ++++----\n src/backend/replication/walsender.c | 8 ++++----\n src/backend/utils/adt/dbsize.c | 8 ++++----\n src/backend/utils/adt/genfile.c | 6 +++---\n src/backend/utils/adt/pgstatfuncs.c | 2 +-\n src/backend/utils/misc/guc.c | 20 ++++++++++----------\n 7 files changed, 32 insertions(+), 32 deletions(-)\n\ndiff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c\nindex 53f48531419..e26ff42fd82 100644\n--- a/src/backend/commands/copy.c\n+++ b/src/backend/commands/copy.c\n@@ -80,26 +80,26 @@ DoCopy(ParseState *pstate, const CopyStmt *stmt,\n \t{\n \t\tif (stmt->is_program)\n \t\t{\n-\t\t\tif (!is_member_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))\n+\t\t\tif (!has_privs_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))\n \t\t\t\tereport(ERROR,\n \t\t\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t\t\t errmsg(\"must be superuser or a member of the pg_execute_server_program role to COPY to or from an external program\"),\n+\t\t\t\t\t\t errmsg(\"must be superuser or have privileges of the pg_execute_server_program role to COPY to or from an external program\"),\n \t\t\t\t\t\t errhint(\"Anyone can COPY to stdout or from stdin. \"\n \t\t\t\t\t\t\t\t \"psql's \\\\copy command also works for anyone.\")));\n \t\t}\n \t\telse\n \t\t{\n-\t\t\tif (is_from && !is_member_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\n+\t\t\tif (is_from && !has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\n \t\t\t\tereport(ERROR,\n \t\t\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t\t\t errmsg(\"must be superuser or a member of the pg_read_server_files role to COPY from a file\"),\n+\t\t\t\t\t\t errmsg(\"must be superuser or have privileges of the pg_read_server_files role to COPY from a file\"),\n \t\t\t\t\t\t errhint(\"Anyone can COPY to stdout or from stdin. \"\n \t\t\t\t\t\t\t\t \"psql's \\\\copy command also works for anyone.\")));\n \n-\t\t\tif (!is_from && !is_member_of_role(GetUserId(), ROLE_PG_WRITE_SERVER_FILES))\n+\t\t\tif (!is_from && !has_privs_of_role(GetUserId(), ROLE_PG_WRITE_SERVER_FILES))\n \t\t\t\tereport(ERROR,\n \t\t\t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t\t\t errmsg(\"must be superuser or a member of the pg_write_server_files role to COPY to a file\"),\n+\t\t\t\t\t\t errmsg(\"must be superuser or have privileges of the pg_write_server_files role to COPY to a file\"),\n \t\t\t\t\t\t errhint(\"Anyone can COPY to stdout or from stdin. \"\n \t\t\t\t\t\t\t\t \"psql's \\\\copy command also works for anyone.\")));\n \t\t}\ndiff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c\nindex b90e5ca98ea..c8ddb6fc323 100644\n--- a/src/backend/replication/walreceiver.c\n+++ b/src/backend/replication/walreceiver.c\n@@ -1392,12 +1392,12 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)\n \t/* Fetch values */\n \tvalues[0] = Int32GetDatum(pid);\n \n-\tif (!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n+\tif (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n \t{\n \t\t/*\n-\t\t * Only superusers and members of pg_read_all_stats can see details.\n-\t\t * Other users only get the pid value to know whether it is a WAL\n-\t\t * receiver, but no details.\n+\t\t * Only superusers and roles with privileges of pg_read_all_stats\n+\t\t * can see details. Other users only get the pid value to know whether\n+\t\t * it is a WAL receiver, but no details.\n \t\t */\n \t\tMemSet(&nulls[1], true, sizeof(bool) * (tupdesc->natts - 1));\n \t}\ndiff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c\nindex d9ab6d6de24..4daf1581bc6 100644\n--- a/src/backend/replication/walsender.c\n+++ b/src/backend/replication/walsender.c\n@@ -3486,12 +3486,12 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)\n \t\tmemset(nulls, 0, sizeof(nulls));\n \t\tvalues[0] = Int32GetDatum(pid);\n \n-\t\tif (!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n+\t\tif (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n \t\t{\n \t\t\t/*\n-\t\t\t * Only superusers and members of pg_read_all_stats can see\n-\t\t\t * details. Other users only get the pid value to know it's a\n-\t\t\t * walsender, but no details.\n+\t\t\t * Only superusers and roles with privileges of pg_read_all_stats\n+\t\t\t * can see details. Other users only get the pid value to know\n+\t\t\t * it's a walsender, but no details.\n \t\t\t */\n \t\t\tMemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);\n \t\t}\ndiff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c\nindex d5a7fb13f3c..95a5d34fdf1 100644\n--- a/src/backend/utils/adt/dbsize.c\n+++ b/src/backend/utils/adt/dbsize.c\n@@ -112,12 +112,12 @@ calculate_database_size(Oid dbOid)\n \tAclResult\taclresult;\n \n \t/*\n-\t * User must have connect privilege for target database or be a member of\n+\t * User must have connect privilege for target database or have privilegs of\n \t * pg_read_all_stats\n \t */\n \taclresult = pg_database_aclcheck(dbOid, GetUserId(), ACL_CONNECT);\n \tif (aclresult != ACLCHECK_OK &&\n-\t\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n+\t\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n \t{\n \t\taclcheck_error(aclresult, OBJECT_DATABASE,\n \t\t\t\t\t get_database_name(dbOid));\n@@ -196,12 +196,12 @@ calculate_tablespace_size(Oid tblspcOid)\n \tAclResult\taclresult;\n \n \t/*\n-\t * User must be a member of pg_read_all_stats or have CREATE privilege for\n+\t * User must have privileges of pg_read_all_stats or have CREATE privilege for\n \t * target tablespace, either explicitly granted or implicitly because it\n \t * is default for current database.\n \t */\n \tif (tblspcOid != MyDatabaseTableSpace &&\n-\t\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n+\t\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\n \t{\n \t\taclresult = pg_tablespace_aclcheck(tblspcOid, GetUserId(), ACL_CREATE);\n \t\tif (aclresult != ACLCHECK_OK)\ndiff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c\nindex c436d9318b6..f87f77093a6 100644\n--- a/src/backend/utils/adt/genfile.c\n+++ b/src/backend/utils/adt/genfile.c\n@@ -58,11 +58,11 @@ convert_and_check_filename(text *arg)\n \tcanonicalize_path(filename);\t/* filename can change length here */\n \n \t/*\n-\t * Members of the 'pg_read_server_files' role are allowed to access any\n-\t * files on the server as the PG user, so no need to do any further checks\n+\t * Roles with privleges of the 'pg_read_server_files' role are allowed to access\n+\t * any files on the server as the PG user, so no need to do any further checks\n \t * here.\n \t */\n-\tif (is_member_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\n+\tif (has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\n \t\treturn filename;\n \n \t/*\ndiff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c\nindex ff5aedc99cb..56762a7d98d 100644\n--- a/src/backend/utils/adt/pgstatfuncs.c\n+++ b/src/backend/utils/adt/pgstatfuncs.c\n@@ -34,7 +34,7 @@\n \n #define UINT32_ACCESS_ONCE(var)\t\t ((uint32)(*((volatile uint32 *)&(var))))\n \n-#define HAS_PGSTAT_PERMISSIONS(role)\t (is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS) || has_privs_of_role(GetUserId(), role))\n+#define HAS_PGSTAT_PERMISSIONS(role)\t (has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS) || has_privs_of_role(GetUserId(), role))\n \n Datum\n pg_stat_get_numscans(PG_FUNCTION_ARGS)\ndiff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c\nindex e91d5a3cfda..e400bfdea13 100644\n--- a/src/backend/utils/misc/guc.c\n+++ b/src/backend/utils/misc/guc.c\n@@ -8154,10 +8154,10 @@ GetConfigOption(const char *name, bool missing_ok, bool restrict_privileged)\n \t\treturn NULL;\n \tif (restrict_privileged &&\n \t\t(record->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n+\t\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n \t\tereport(ERROR,\n \t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t errmsg(\"must be superuser or a member of pg_read_all_settings to examine \\\"%s\\\"\",\n+\t\t\t\t errmsg(\"must be superuser have privileges of pg_read_all_settings to examine \\\"%s\\\"\",\n \t\t\t\t\t\tname)));\n \n \tswitch (record->vartype)\n@@ -8201,10 +8201,10 @@ GetConfigOptionResetString(const char *name)\n \trecord = find_option(name, false, false, ERROR);\n \tAssert(record != NULL);\n \tif ((record->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n+\t\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n \t\tereport(ERROR,\n \t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t errmsg(\"must be superuser or a member of pg_read_all_settings to examine \\\"%s\\\"\",\n+\t\t\t\t errmsg(\"must be superuser or have privileges of pg_read_all_settings to examine \\\"%s\\\"\",\n \t\t\t\t\t\tname)));\n \n \tswitch (record->vartype)\n@@ -9448,7 +9448,7 @@ ShowAllGUCConfig(DestReceiver *dest)\n \n \t\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\n \t\t\t((conf->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n+\t\t\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n \t\t\tcontinue;\n \n \t\t/* assign to the values array */\n@@ -9515,7 +9515,7 @@ get_explain_guc_options(int *num)\n \t\t/* return only options visible to the current user */\n \t\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\n \t\t\t((conf->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n+\t\t\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n \t\t\tcontinue;\n \n \t\t/* return only options that are different from their boot values */\n@@ -9597,10 +9597,10 @@ GetConfigOptionByName(const char *name, const char **varname, bool missing_ok)\n \t}\n \n \tif ((record->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n+\t\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n \t\tereport(ERROR,\n \t\t\t\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\n-\t\t\t\t errmsg(\"must be superuser or a member of pg_read_all_settings to examine \\\"%s\\\"\",\n+\t\t\t\t errmsg(\"must be superuser or have privileges of pg_read_all_settings to examine \\\"%s\\\"\",\n \t\t\t\t\t\tname)));\n \n \tif (varname)\n@@ -9628,7 +9628,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)\n \t{\n \t\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\n \t\t\t((conf->flags & GUC_SUPERUSER_ONLY) &&\n-\t\t\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n+\t\t\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\n \t\t\t*noshow = true;\n \t\telse\n \t\t\t*noshow = false;\n@@ -9823,7 +9823,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)\n \t * insufficiently-privileged users.\n \t */\n \tif (conf->source == PGC_S_FILE &&\n-\t\tis_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n+\t\thas_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\n \t{\n \t\tvalues[14] = conf->sourcefile;\n \t\tsnprintf(buffer, sizeof(buffer), \"%d\", conf->sourceline);\n-- \n2.31.1\n\n\n\n","msg_date":"Tue, 26 Oct 2021 15:47:31 -0700","msg_from":"Joshua Brindle <joshua.brindle@crunchydata.com>","msg_from_op":true,"msg_subject":"[PATCH] Conflation of member/privs for predefined roles"},{"msg_contents":"On 10/26/21, 3:50 PM, \"Joshua Brindle\" <joshua.brindle@crunchydata.com> wrote:\r\n> Generally if a role is granted membership to another role with NOINHERIT\r\n> they must use SET ROLE to access the privileges of that role, however\r\n> with predefined roles the membership and privilege is conflated, as\r\n> demonstrated by:\r\n\r\nI think it makes sense that INHERIT/NOINHERIT should be respected for\r\nthe predefined roles. I went through some of the old threads and\r\ncommits for predefined roles, and I didn't find any mention of\r\ninheritance, so there might not be a strong reason it was done this\r\nway.\r\n\r\nI saw a few places in the docs that will likely need to be updated as\r\nwell. For example, pg_freespacemap has this note:\r\n\r\n By default use is restricted to superusers and members of the pg_stat_scan_tables role.\r\n\r\nAnd I found at least one test (rolenames.sql) that fails due to the\r\nnew ERROR message.\r\n\r\nNathan\r\n\r\n","msg_date":"Wed, 27 Oct 2021 17:20:09 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: [PATCH] Conflation of member/privs for predefined roles"},{"msg_contents":"On Wed, Oct 27, 2021 at 1:20 PM Bossart, Nathan <bossartn@amazon.com> wrote:\n>\n> On 10/26/21, 3:50 PM, \"Joshua Brindle\" <joshua.brindle@crunchydata.com> wrote:\n> > Generally if a role is granted membership to another role with NOINHERIT\n> > they must use SET ROLE to access the privileges of that role, however\n> > with predefined roles the membership and privilege is conflated, as\n> > demonstrated by:\n>\n> I think it makes sense that INHERIT/NOINHERIT should be respected for\n> the predefined roles. I went through some of the old threads and\n> commits for predefined roles, and I didn't find any mention of\n> inheritance, so there might not be a strong reason it was done this\n> way.\n\nThank you for looking into this. We believe this was a mistake and I\nhave a follow-up patch to remove is_member_of_role() from the header\nto avoid it going forward.\n\nAt least one new pre-defined role patch (pg_maintenance) was recently\nsubmitted using has_privs_of_role() so it seems like there is a need\nfor consistency regardless.\n\n> I saw a few places in the docs that will likely need to be updated as\n> well. For example, pg_freespacemap has this note:\n>\n> By default use is restricted to superusers and members of the pg_stat_scan_tables role.\n>\n> And I found at least one test (rolenames.sql) that fails due to the\n> new ERROR message.\n\nI'm new to contributing here but I've been told that the string\nchanges get taken care of later, is that not true?\n\n\n","msg_date":"Wed, 27 Oct 2021 13:27:14 -0400","msg_from":"Joshua Brindle <joshua.brindle@crunchydata.com>","msg_from_op":true,"msg_subject":"Re: [PATCH] Conflation of member/privs for predefined roles"},{"msg_contents":"On 10/27/21, 10:28 AM, \"Joshua Brindle\" <joshua.brindle@crunchydata.com> wrote:\r\n> I'm new to contributing here but I've been told that the string\r\n> changes get taken care of later, is that not true?\r\n\r\nI will sometimes leave out tests and docs until I get buy-in on the\r\napproach. But for serious consideration, I think the patch has to be\r\nmore-or-less complete.\r\n\r\nNathan\r\n\r\n","msg_date":"Wed, 27 Oct 2021 17:34:13 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: [PATCH] Conflation of member/privs for predefined roles"},{"msg_contents":"On Wed, Oct 27, 2021 at 1:34 PM Bossart, Nathan <bossartn@amazon.com> wrote:\n>\n> On 10/27/21, 10:28 AM, \"Joshua Brindle\" <joshua.brindle@crunchydata.com> wrote:\n> > I'm new to contributing here but I've been told that the string\n> > changes get taken care of later, is that not true?\n>\n> I will sometimes leave out tests and docs until I get buy-in on the\n> approach. But for serious consideration, I think the patch has to be\n> more-or-less complete.\n>\n\nThanks, I'll fix those and resubmit both patches in a single email\nsince one depends on the other.\n\n\n","msg_date":"Wed, 27 Oct 2021 13:54:06 -0400","msg_from":"Joshua Brindle <joshua.brindle@crunchydata.com>","msg_from_op":true,"msg_subject":"Re: [PATCH] Conflation of member/privs for predefined roles"}],"string":"[\n {\n \"msg_contents\": \"Generally if a role is granted membership to another role with NOINHERIT\\nthey must use SET ROLE to access the privileges of that role, however\\nwith predefined roles the membership and privilege is conflated, as\\ndemonstrated by:\\n\\nCREATE ROLE readrole;\\nCREATE ROLE role2 NOINHERIT;\\nCREATE ROLE brindle LOGIN;\\n\\nGRANT role2 TO brindle;\\nCREATE TABLE foo(i INT);\\nGRANT readrole TO role2;\\nGRANT ALL ON TABLE foo TO readrole;\\n\\nGRANT pg_read_all_stats,pg_read_all_settings,pg_read_server_files,pg_write_server_files,pg_execute_server_program TO role2;\\n\\nLog in as brindle:\\n\\npostgres=> select current_user;\\n current_user\\n--------------\\n brindle\\n(1 row)\\n\\npostgres=> SELECT * FROM foo;\\nERROR: permission denied for table foo\\n\\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\\n query\\n----------------------------------------------\\n\\n SELECT DISTINCT query FROM pg_stat_activity;\\n(2 rows)\\n\\npostgres=> SET ROLE readrole;\\nSET\\npostgres=> SELECT * FROM foo;\\n i\\n---\\n(0 rows)\\n\\nAfter this patch:\\n\\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\\n query\\n--------------------------\\n <insufficient privilege>\\n(1 row)\\n\\npostgres=> SET ROLE pg_read_all_stats;\\nSET\\npostgres=> SELECT DISTINCT query FROM pg_stat_activity;\\n query\\n----------------------------------------------\\n\\n SELECT DISTINCT query FROM pg_stat_activity;\\n(2 rows)\\n\\npostgres=> SHOW config_file;\\nERROR: must be superuser or have privileges of pg_read_all_settings to examine \\\"config_file\\\"\\npostgres=> SET ROLE pg_read_all_settings;\\nSET\\npostgres=> SHOW config_file;\\n config_file\\n-----------------------------------\\n /var/lib/pgsql/15/postgresql.conf\\n(1 row)\\n\\nWith inheritance it works as expected:\\n\\nALTER ROLE role2 INHERIT;\\n\\npostgres=> SELECT current_user;\\n current_user\\n--------------\\n brindle\\n(1 row)\\n\\npostgres=> SHOW config_file;\\n config_file\\n-----------------------------------\\n /var/lib/pgsql/15/postgresql.conf\\n(1 row)\\n\\nSigned-off-by: Joshua Brindle <joshua.brindle@crunchydata.com>\\n---\\n src/backend/commands/copy.c | 12 ++++++------\\n src/backend/replication/walreceiver.c | 8 ++++----\\n src/backend/replication/walsender.c | 8 ++++----\\n src/backend/utils/adt/dbsize.c | 8 ++++----\\n src/backend/utils/adt/genfile.c | 6 +++---\\n src/backend/utils/adt/pgstatfuncs.c | 2 +-\\n src/backend/utils/misc/guc.c | 20 ++++++++++----------\\n 7 files changed, 32 insertions(+), 32 deletions(-)\\n\\ndiff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c\\nindex 53f48531419..e26ff42fd82 100644\\n--- a/src/backend/commands/copy.c\\n+++ b/src/backend/commands/copy.c\\n@@ -80,26 +80,26 @@ DoCopy(ParseState *pstate, const CopyStmt *stmt,\\n \\t{\\n \\t\\tif (stmt->is_program)\\n \\t\\t{\\n-\\t\\t\\tif (!is_member_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))\\n+\\t\\t\\tif (!has_privs_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))\\n \\t\\t\\t\\tereport(ERROR,\\n \\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of the pg_execute_server_program role to COPY to or from an external program\\\"),\\n+\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or have privileges of the pg_execute_server_program role to COPY to or from an external program\\\"),\\n \\t\\t\\t\\t\\t\\t errhint(\\\"Anyone can COPY to stdout or from stdin. \\\"\\n \\t\\t\\t\\t\\t\\t\\t\\t \\\"psql's \\\\\\\\copy command also works for anyone.\\\")));\\n \\t\\t}\\n \\t\\telse\\n \\t\\t{\\n-\\t\\t\\tif (is_from && !is_member_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\\n+\\t\\t\\tif (is_from && !has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\\n \\t\\t\\t\\tereport(ERROR,\\n \\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of the pg_read_server_files role to COPY from a file\\\"),\\n+\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or have privileges of the pg_read_server_files role to COPY from a file\\\"),\\n \\t\\t\\t\\t\\t\\t errhint(\\\"Anyone can COPY to stdout or from stdin. \\\"\\n \\t\\t\\t\\t\\t\\t\\t\\t \\\"psql's \\\\\\\\copy command also works for anyone.\\\")));\\n \\n-\\t\\t\\tif (!is_from && !is_member_of_role(GetUserId(), ROLE_PG_WRITE_SERVER_FILES))\\n+\\t\\t\\tif (!is_from && !has_privs_of_role(GetUserId(), ROLE_PG_WRITE_SERVER_FILES))\\n \\t\\t\\t\\tereport(ERROR,\\n \\t\\t\\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of the pg_write_server_files role to COPY to a file\\\"),\\n+\\t\\t\\t\\t\\t\\t errmsg(\\\"must be superuser or have privileges of the pg_write_server_files role to COPY to a file\\\"),\\n \\t\\t\\t\\t\\t\\t errhint(\\\"Anyone can COPY to stdout or from stdin. \\\"\\n \\t\\t\\t\\t\\t\\t\\t\\t \\\"psql's \\\\\\\\copy command also works for anyone.\\\")));\\n \\t\\t}\\ndiff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c\\nindex b90e5ca98ea..c8ddb6fc323 100644\\n--- a/src/backend/replication/walreceiver.c\\n+++ b/src/backend/replication/walreceiver.c\\n@@ -1392,12 +1392,12 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)\\n \\t/* Fetch values */\\n \\tvalues[0] = Int32GetDatum(pid);\\n \\n-\\tif (!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n+\\tif (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n \\t{\\n \\t\\t/*\\n-\\t\\t * Only superusers and members of pg_read_all_stats can see details.\\n-\\t\\t * Other users only get the pid value to know whether it is a WAL\\n-\\t\\t * receiver, but no details.\\n+\\t\\t * Only superusers and roles with privileges of pg_read_all_stats\\n+\\t\\t * can see details. Other users only get the pid value to know whether\\n+\\t\\t * it is a WAL receiver, but no details.\\n \\t\\t */\\n \\t\\tMemSet(&nulls[1], true, sizeof(bool) * (tupdesc->natts - 1));\\n \\t}\\ndiff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c\\nindex d9ab6d6de24..4daf1581bc6 100644\\n--- a/src/backend/replication/walsender.c\\n+++ b/src/backend/replication/walsender.c\\n@@ -3486,12 +3486,12 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)\\n \\t\\tmemset(nulls, 0, sizeof(nulls));\\n \\t\\tvalues[0] = Int32GetDatum(pid);\\n \\n-\\t\\tif (!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n+\\t\\tif (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n \\t\\t{\\n \\t\\t\\t/*\\n-\\t\\t\\t * Only superusers and members of pg_read_all_stats can see\\n-\\t\\t\\t * details. Other users only get the pid value to know it's a\\n-\\t\\t\\t * walsender, but no details.\\n+\\t\\t\\t * Only superusers and roles with privileges of pg_read_all_stats\\n+\\t\\t\\t * can see details. Other users only get the pid value to know\\n+\\t\\t\\t * it's a walsender, but no details.\\n \\t\\t\\t */\\n \\t\\t\\tMemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);\\n \\t\\t}\\ndiff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c\\nindex d5a7fb13f3c..95a5d34fdf1 100644\\n--- a/src/backend/utils/adt/dbsize.c\\n+++ b/src/backend/utils/adt/dbsize.c\\n@@ -112,12 +112,12 @@ calculate_database_size(Oid dbOid)\\n \\tAclResult\\taclresult;\\n \\n \\t/*\\n-\\t * User must have connect privilege for target database or be a member of\\n+\\t * User must have connect privilege for target database or have privilegs of\\n \\t * pg_read_all_stats\\n \\t */\\n \\taclresult = pg_database_aclcheck(dbOid, GetUserId(), ACL_CONNECT);\\n \\tif (aclresult != ACLCHECK_OK &&\\n-\\t\\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n+\\t\\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n \\t{\\n \\t\\taclcheck_error(aclresult, OBJECT_DATABASE,\\n \\t\\t\\t\\t\\t get_database_name(dbOid));\\n@@ -196,12 +196,12 @@ calculate_tablespace_size(Oid tblspcOid)\\n \\tAclResult\\taclresult;\\n \\n \\t/*\\n-\\t * User must be a member of pg_read_all_stats or have CREATE privilege for\\n+\\t * User must have privileges of pg_read_all_stats or have CREATE privilege for\\n \\t * target tablespace, either explicitly granted or implicitly because it\\n \\t * is default for current database.\\n \\t */\\n \\tif (tblspcOid != MyDatabaseTableSpace &&\\n-\\t\\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n+\\t\\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))\\n \\t{\\n \\t\\taclresult = pg_tablespace_aclcheck(tblspcOid, GetUserId(), ACL_CREATE);\\n \\t\\tif (aclresult != ACLCHECK_OK)\\ndiff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c\\nindex c436d9318b6..f87f77093a6 100644\\n--- a/src/backend/utils/adt/genfile.c\\n+++ b/src/backend/utils/adt/genfile.c\\n@@ -58,11 +58,11 @@ convert_and_check_filename(text *arg)\\n \\tcanonicalize_path(filename);\\t/* filename can change length here */\\n \\n \\t/*\\n-\\t * Members of the 'pg_read_server_files' role are allowed to access any\\n-\\t * files on the server as the PG user, so no need to do any further checks\\n+\\t * Roles with privleges of the 'pg_read_server_files' role are allowed to access\\n+\\t * any files on the server as the PG user, so no need to do any further checks\\n \\t * here.\\n \\t */\\n-\\tif (is_member_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\\n+\\tif (has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))\\n \\t\\treturn filename;\\n \\n \\t/*\\ndiff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c\\nindex ff5aedc99cb..56762a7d98d 100644\\n--- a/src/backend/utils/adt/pgstatfuncs.c\\n+++ b/src/backend/utils/adt/pgstatfuncs.c\\n@@ -34,7 +34,7 @@\\n \\n #define UINT32_ACCESS_ONCE(var)\\t\\t ((uint32)(*((volatile uint32 *)&(var))))\\n \\n-#define HAS_PGSTAT_PERMISSIONS(role)\\t (is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS) || has_privs_of_role(GetUserId(), role))\\n+#define HAS_PGSTAT_PERMISSIONS(role)\\t (has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS) || has_privs_of_role(GetUserId(), role))\\n \\n Datum\\n pg_stat_get_numscans(PG_FUNCTION_ARGS)\\ndiff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c\\nindex e91d5a3cfda..e400bfdea13 100644\\n--- a/src/backend/utils/misc/guc.c\\n+++ b/src/backend/utils/misc/guc.c\\n@@ -8154,10 +8154,10 @@ GetConfigOption(const char *name, bool missing_ok, bool restrict_privileged)\\n \\t\\treturn NULL;\\n \\tif (restrict_privileged &&\\n \\t\\t(record->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n+\\t\\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n \\t\\tereport(ERROR,\\n \\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n+\\t\\t\\t\\t errmsg(\\\"must be superuser have privileges of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n \\t\\t\\t\\t\\t\\tname)));\\n \\n \\tswitch (record->vartype)\\n@@ -8201,10 +8201,10 @@ GetConfigOptionResetString(const char *name)\\n \\trecord = find_option(name, false, false, ERROR);\\n \\tAssert(record != NULL);\\n \\tif ((record->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n+\\t\\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n \\t\\tereport(ERROR,\\n \\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n+\\t\\t\\t\\t errmsg(\\\"must be superuser or have privileges of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n \\t\\t\\t\\t\\t\\tname)));\\n \\n \\tswitch (record->vartype)\\n@@ -9448,7 +9448,7 @@ ShowAllGUCConfig(DestReceiver *dest)\\n \\n \\t\\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\\n \\t\\t\\t((conf->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t\\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n+\\t\\t\\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n \\t\\t\\tcontinue;\\n \\n \\t\\t/* assign to the values array */\\n@@ -9515,7 +9515,7 @@ get_explain_guc_options(int *num)\\n \\t\\t/* return only options visible to the current user */\\n \\t\\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\\n \\t\\t\\t((conf->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t\\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n+\\t\\t\\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n \\t\\t\\tcontinue;\\n \\n \\t\\t/* return only options that are different from their boot values */\\n@@ -9597,10 +9597,10 @@ GetConfigOptionByName(const char *name, const char **varname, bool missing_ok)\\n \\t}\\n \\n \\tif ((record->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n+\\t\\t!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n \\t\\tereport(ERROR,\\n \\t\\t\\t\\t(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),\\n-\\t\\t\\t\\t errmsg(\\\"must be superuser or a member of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n+\\t\\t\\t\\t errmsg(\\\"must be superuser or have privileges of pg_read_all_settings to examine \\\\\\\"%s\\\\\\\"\\\",\\n \\t\\t\\t\\t\\t\\tname)));\\n \\n \\tif (varname)\\n@@ -9628,7 +9628,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)\\n \\t{\\n \\t\\tif ((conf->flags & GUC_NO_SHOW_ALL) ||\\n \\t\\t\\t((conf->flags & GUC_SUPERUSER_ONLY) &&\\n-\\t\\t\\t !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n+\\t\\t\\t !has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))\\n \\t\\t\\t*noshow = true;\\n \\t\\telse\\n \\t\\t\\t*noshow = false;\\n@@ -9823,7 +9823,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)\\n \\t * insufficiently-privileged users.\\n \\t */\\n \\tif (conf->source == PGC_S_FILE &&\\n-\\t\\tis_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n+\\t\\thas_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))\\n \\t{\\n \\t\\tvalues[14] = conf->sourcefile;\\n \\t\\tsnprintf(buffer, sizeof(buffer), \\\"%d\\\", conf->sourceline);\\n-- \\n2.31.1\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 15:47:31 -0700\",\n \"msg_from\": \"Joshua Brindle <joshua.brindle@crunchydata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"[PATCH] Conflation of member/privs for predefined roles\"\n },\n {\n \"msg_contents\": \"On 10/26/21, 3:50 PM, \\\"Joshua Brindle\\\" <joshua.brindle@crunchydata.com> wrote:\\r\\n> Generally if a role is granted membership to another role with NOINHERIT\\r\\n> they must use SET ROLE to access the privileges of that role, however\\r\\n> with predefined roles the membership and privilege is conflated, as\\r\\n> demonstrated by:\\r\\n\\r\\nI think it makes sense that INHERIT/NOINHERIT should be respected for\\r\\nthe predefined roles. I went through some of the old threads and\\r\\ncommits for predefined roles, and I didn't find any mention of\\r\\ninheritance, so there might not be a strong reason it was done this\\r\\nway.\\r\\n\\r\\nI saw a few places in the docs that will likely need to be updated as\\r\\nwell. For example, pg_freespacemap has this note:\\r\\n\\r\\n By default use is restricted to superusers and members of the pg_stat_scan_tables role.\\r\\n\\r\\nAnd I found at least one test (rolenames.sql) that fails due to the\\r\\nnew ERROR message.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 17:20:09 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH] Conflation of member/privs for predefined roles\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 1:20 PM Bossart, Nathan <bossartn@amazon.com> wrote:\\n>\\n> On 10/26/21, 3:50 PM, \\\"Joshua Brindle\\\" <joshua.brindle@crunchydata.com> wrote:\\n> > Generally if a role is granted membership to another role with NOINHERIT\\n> > they must use SET ROLE to access the privileges of that role, however\\n> > with predefined roles the membership and privilege is conflated, as\\n> > demonstrated by:\\n>\\n> I think it makes sense that INHERIT/NOINHERIT should be respected for\\n> the predefined roles. I went through some of the old threads and\\n> commits for predefined roles, and I didn't find any mention of\\n> inheritance, so there might not be a strong reason it was done this\\n> way.\\n\\nThank you for looking into this. We believe this was a mistake and I\\nhave a follow-up patch to remove is_member_of_role() from the header\\nto avoid it going forward.\\n\\nAt least one new pre-defined role patch (pg_maintenance) was recently\\nsubmitted using has_privs_of_role() so it seems like there is a need\\nfor consistency regardless.\\n\\n> I saw a few places in the docs that will likely need to be updated as\\n> well. For example, pg_freespacemap has this note:\\n>\\n> By default use is restricted to superusers and members of the pg_stat_scan_tables role.\\n>\\n> And I found at least one test (rolenames.sql) that fails due to the\\n> new ERROR message.\\n\\nI'm new to contributing here but I've been told that the string\\nchanges get taken care of later, is that not true?\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 13:27:14 -0400\",\n \"msg_from\": \"Joshua Brindle <joshua.brindle@crunchydata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PATCH] Conflation of member/privs for predefined roles\"\n },\n {\n \"msg_contents\": \"On 10/27/21, 10:28 AM, \\\"Joshua Brindle\\\" <joshua.brindle@crunchydata.com> wrote:\\r\\n> I'm new to contributing here but I've been told that the string\\r\\n> changes get taken care of later, is that not true?\\r\\n\\r\\nI will sometimes leave out tests and docs until I get buy-in on the\\r\\napproach. But for serious consideration, I think the patch has to be\\r\\nmore-or-less complete.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 17:34:13 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PATCH] Conflation of member/privs for predefined roles\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 1:34 PM Bossart, Nathan <bossartn@amazon.com> wrote:\\n>\\n> On 10/27/21, 10:28 AM, \\\"Joshua Brindle\\\" <joshua.brindle@crunchydata.com> wrote:\\n> > I'm new to contributing here but I've been told that the string\\n> > changes get taken care of later, is that not true?\\n>\\n> I will sometimes leave out tests and docs until I get buy-in on the\\n> approach. But for serious consideration, I think the patch has to be\\n> more-or-less complete.\\n>\\n\\nThanks, I'll fix those and resubmit both patches in a single email\\nsince one depends on the other.\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 13:54:06 -0400\",\n \"msg_from\": \"Joshua Brindle <joshua.brindle@crunchydata.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PATCH] Conflation of member/privs for predefined roles\"\n }\n]","isConversational":false}}},{"rowIdx":52997,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\n\nA while back I'd reported [1] to the wine bugs list that their popen() doesn't\nquite work. Which I noticed because it made initdb.exe hang in wine.\n\nThat was just fixed. And I verified that with a bleeding edge wine the windows\ninitdb.exe actually succeeds (although I nuked the root/admin check for now).\n\nI mostly was interested in that to make it easier to do changes that affect\nwindows from linux, without having to wait for the buildfarm / cfbot / CI to\ncome back with the inevitable problem.\n\nGreetings,\n\nAndres Freund\n\n[1] https://bugs.winehq.org/show_bug.cgi?id=51719\n\n\n","msg_date":"Tue, 26 Oct 2021 17:22:15 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":true,"msg_subject":"heads up: initdb.exe now succeeds in wine"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\n\\nA while back I'd reported [1] to the wine bugs list that their popen() doesn't\\nquite work. Which I noticed because it made initdb.exe hang in wine.\\n\\nThat was just fixed. And I verified that with a bleeding edge wine the windows\\ninitdb.exe actually succeeds (although I nuked the root/admin check for now).\\n\\nI mostly was interested in that to make it easier to do changes that affect\\nwindows from linux, without having to wait for the buildfarm / cfbot / CI to\\ncome back with the inevitable problem.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n[1] https://bugs.winehq.org/show_bug.cgi?id=51719\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Oct 2021 17:22:15 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"heads up: initdb.exe now succeeds in wine\"\n }\n]","isConversational":false}}},{"rowIdx":52998,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"I've been investigating the poor performance of a WITH RECURSIVE\nquery, which I've recreated with test data.\n\nThe first thing was to re-write the query, which helped improve\nperformance by about 30%, but the plan was still very bad. With a\nsmall patch I've been able to improve performance by about x100.\n\nThe poor performance is traced to the planner cost estimates for\nrecursive queries. Specifically, the cost of the recursive arm of the\nquery is evaluated based upon both of these hardcoded assumptions:\n\n1. The recursion will last for 10 loops\n2. The average size of the worktable will be 10x the size of the\ninitial query (non-recursive term).\n\nTaken together these assumptions lead to a very poor estimate of the\nworktable activity (in this case), which leads to the plan changing as\na result.\n\nThe factor 10 is a reasonably safe assumption and helps avoid worst\ncase behavior in bigger graph queries. However, the factor 10 is way\ntoo large for many types of graph query, such as where the path\nthrough the data is tight, and/or the query is written to prune bushy\ngraphs, e.g. shortest path queries. The factor 10 should not be\nhardcoded in the planner, but should be settable, just as\ncursor_tuple_fraction is.\n\nI've written a short patch to make the estimate of the avg size of the\nworktable configurable:\n\n recursive_worktable_estimate = N (default 10)\n\nUsing this parameter with the test query results in a consistently\nrepeatable ~100x gain in performance, using\nrecursive_worktable_estimate = 1 for a shortest path query:\n\nUnpatched: 1775ms\nPatched: 17.2ms\n\nThis is because the estimated size of the worktable is closer to the\ntruth and so leads naturally to a more sensible plan. EXPLAINs\nattached - please look at the estimated rows for the WorkTable Scan.\n\nThere are various options for setting the two estimates: just one, or\nother, or both values separately, or both together. Note that I\nhaven't touched the estimate that recursion will last for 10 loops. I\nfigured that people would object to two knobs.\n\nThoughts?\n\n\nThere are 2 other ways to speed up the query. One is to set\nenable_seqscan = off, which helps about 20%, but may have other\nconsequences. Two is to set work_mem = 512MB, so that the poor plan\n(hash) works as fast as possible, but that is far from optimal either.\nGetting the right plan is x20 faster than either of those\nalternatives.\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/","msg_date":"Wed, 27 Oct 2021 15:58:58 +0100","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Parameter for planner estimate of recursive queries"},{"msg_contents":"On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\n\n> The poor performance is traced to the planner cost estimates for\n> recursive queries. Specifically, the cost of the recursive arm of the\n> query is evaluated based upon both of these hardcoded assumptions:\n>\n> 1. The recursion will last for 10 loops\n> 2. The average size of the worktable will be 10x the size of the\n> initial query (non-recursive term).\n>\n> Taken together these assumptions lead to a very poor estimate of the\n> worktable activity (in this case), which leads to the plan changing as\n> a result.\n>\n> The factor 10 is a reasonably safe assumption and helps avoid worst\n> case behavior in bigger graph queries. However, the factor 10 is way\n> too large for many types of graph query, such as where the path\n> through the data is tight, and/or the query is written to prune bushy\n> graphs, e.g. shortest path queries. The factor 10 should not be\n> hardcoded in the planner, but should be settable, just as\n> cursor_tuple_fraction is.\n\nIf you think this should be derived without parameters, then we would\nwant a function that starts at 1 for 1 input row and gets much larger\nfor larger input. The thinking here is that Graph OLTP is often a\nshortest path between two nodes, whereas Graph Analytics and so the\nworktable will get much bigger.\n\nSo I'm, thinking we use\n\nrel->tuples = min(1, cte_rows * cte_rows/2);\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/\n\n\n","msg_date":"Fri, 31 Dec 2021 14:10:12 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"> The factor 10 should not be hardcoded in the planner, but should be\nsettable, just as cursor_tuple_fraction is.\n\nI feel considerably out of my depth here, but I like the idea of a working\ntable size multiplier GUC, given the challenges of predicting the number of\niterations (and any adjustments to cardinality per iteration). An\nexponential cost function may lead to increasingly pathological outcomes,\nespecially when estimates for cte_rows are off.\n\nIn the EXPLAINs, it looked like the estimates for knows_pkey were off by an\norder of magnitude or so. It's possible the planner would have chosen the\nNested Loop plan if knows_pkey had estimated to rows=87 (as the WindowAgg\nwould have estimated to roughly the same size as the second plan anyways,\neven with rel->tuples = 10 * cte_rows).\n\nI also wonder if there's a better default than cte_rows * 10, but\nimplementing a new GUC sounds like a reasonable solution to this as well.\n\n--\n\nKenaniah\n\nOn Sat, Jan 22, 2022 at 1:58 PM Simon Riggs <simon.riggs@enterprisedb.com>\nwrote:\n\n> On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com>\n> wrote:\n>\n> > The poor performance is traced to the planner cost estimates for\n> > recursive queries. Specifically, the cost of the recursive arm of the\n> > query is evaluated based upon both of these hardcoded assumptions:\n> >\n> > 1. The recursion will last for 10 loops\n> > 2. The average size of the worktable will be 10x the size of the\n> > initial query (non-recursive term).\n> >\n> > Taken together these assumptions lead to a very poor estimate of the\n> > worktable activity (in this case), which leads to the plan changing as\n> > a result.\n> >\n> > The factor 10 is a reasonably safe assumption and helps avoid worst\n> > case behavior in bigger graph queries. However, the factor 10 is way\n> > too large for many types of graph query, such as where the path\n> > through the data is tight, and/or the query is written to prune bushy\n> > graphs, e.g. shortest path queries. The factor 10 should not be\n> > hardcoded in the planner, but should be settable, just as\n> > cursor_tuple_fraction is.\n>\n> If you think this should be derived without parameters, then we would\n> want a function that starts at 1 for 1 input row and gets much larger\n> for larger input. The thinking here is that Graph OLTP is often a\n> shortest path between two nodes, whereas Graph Analytics and so the\n> worktable will get much bigger.\n>\n> So I'm, thinking we use\n>\n> rel->tuples = min(1, cte_rows * cte_rows/2);\n>\n> --\n> Simon Riggs http://www.EnterpriseDB.com/\n>\n>\n>\n>\n>\n\n> The factor 10 should not be hardcoded in the planner, but should be settable, just as cursor_tuple_fraction is.I feel considerably out of my depth here, but I like the idea of a working table size multiplier GUC, given the challenges of predicting the number of iterations (and any adjustments to cardinality per iteration). An exponential cost function may lead to increasingly pathological outcomes, especially when estimates for cte_rows are off. In the EXPLAINs, it looked like the estimates for knows_pkey were off by an order of magnitude or so. It's possible the planner would have chosen the Nested Loop plan if knows_pkey had estimated to rows=87 (as the WindowAgg would have estimated to roughly the same size as the second plan anyways, even with rel->tuples = 10 * cte_rows).I also wonder if there's a better default than cte_rows * 10, but implementing a new GUC sounds like a reasonable solution to this as well.--KenaniahOn Sat, Jan 22, 2022 at 1:58 PM Simon Riggs <simon.riggs@enterprisedb.com> wrote:On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\n\n> The poor performance is traced to the planner cost estimates for\n> recursive queries. Specifically, the cost of the recursive arm of the\n> query is evaluated based upon both of these hardcoded assumptions:\n>\n> 1. The recursion will last for 10 loops\n> 2. The average size of the worktable will be 10x the size of the\n> initial query (non-recursive term).\n>\n> Taken together these assumptions lead to a very poor estimate of the\n> worktable activity (in this case), which leads to the plan changing as\n> a result.\n>\n> The factor 10 is a reasonably safe assumption and helps avoid worst\n> case behavior in bigger graph queries. However, the factor 10 is way\n> too large for many types of graph query, such as where the path\n> through the data is tight, and/or the query is written to prune bushy\n> graphs, e.g. shortest path queries. The factor 10 should not be\n> hardcoded in the planner, but should be settable, just as\n> cursor_tuple_fraction is.\n\nIf you think this should be derived without parameters, then we would\nwant a function that starts at 1 for 1 input row and gets much larger\nfor larger input. The thinking here is that Graph OLTP is often a\nshortest path between two nodes, whereas Graph Analytics and so the\nworktable will get much bigger.\n\nSo I'm, thinking we use\n\nrel->tuples = min(1, cte_rows * cte_rows/2);\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/","msg_date":"Sat, 22 Jan 2022 14:33:59 -0800","msg_from":"Kenaniah Cerny <kenaniah@gmail.com>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On 31.12.21 15:10, Simon Riggs wrote:\n>> The factor 10 is a reasonably safe assumption and helps avoid worst\n>> case behavior in bigger graph queries. However, the factor 10 is way\n>> too large for many types of graph query, such as where the path\n>> through the data is tight, and/or the query is written to prune bushy\n>> graphs, e.g. shortest path queries. The factor 10 should not be\n>> hardcoded in the planner, but should be settable, just as\n>> cursor_tuple_fraction is.\n> If you think this should be derived without parameters, then we would\n> want a function that starts at 1 for 1 input row and gets much larger\n> for larger input. The thinking here is that Graph OLTP is often a\n> shortest path between two nodes, whereas Graph Analytics and so the\n> worktable will get much bigger.\n\nOn the one hand, this smells like a planner hint. But on the other \nhand, it doesn't look like we will come up with proper graph-aware \nselectivity estimation system any time soon, so just having all graph \nOLTP queries suck until then because the planner hint is hardcoded \ndoesn't seem like a better solution. So I think this setting can be ok. \n I think the way you have characterized it makes sense, too: for graph \nOLAP, you want a larger value, for graph OLTP, you want a smaller value.\n\n\n\n","msg_date":"Tue, 25 Jan 2022 10:44:21 +0100","msg_from":"Peter Eisentraut <peter.eisentraut@enterprisedb.com>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Tue, 25 Jan 2022 at 14:44, Peter Eisentraut <\npeter.eisentraut@enterprisedb.com> wrote:\n\n> On 31.12.21 15:10, Simon Riggs wrote:\n> >> The factor 10 is a reasonably safe assumption and helps avoid worst\n> >> case behavior in bigger graph queries. However, the factor 10 is way\n> >> too large for many types of graph query, such as where the path\n> >> through the data is tight, and/or the query is written to prune bushy\n> >> graphs, e.g. shortest path queries. The factor 10 should not be\n> >> hardcoded in the planner, but should be settable, just as\n> >> cursor_tuple_fraction is.\n> > If you think this should be derived without parameters, then we would\n> > want a function that starts at 1 for 1 input row and gets much larger\n> > for larger input. The thinking here is that Graph OLTP is often a\n> > shortest path between two nodes, whereas Graph Analytics and so the\n> > worktable will get much bigger.\n>\n> On the one hand, this smells like a planner hint. But on the other\n> hand, it doesn't look like we will come up with proper graph-aware\n> selectivity estimation system any time soon, so just having all graph\n> OLTP queries suck until then because the planner hint is hardcoded\n> doesn't seem like a better solution. So I think this setting can be ok.\n> I think the way you have characterized it makes sense, too: for graph\n> OLAP, you want a larger value, for graph OLTP, you want a smaller value.\n>\n\nDo you think there is a case to replace the 10x multiplier with\n\"recursive_worktable_estimate\" for total_rows calculation in the\ncost_recursive_union function too?\n\nOn Tue, 25 Jan 2022 at 14:44, Peter Eisentraut <peter.eisentraut@enterprisedb.com> wrote:On 31.12.21 15:10, Simon Riggs wrote:\n>> The factor 10 is a reasonably safe assumption and helps avoid worst\n>> case behavior in bigger graph queries. However, the factor 10 is way\n>> too large for many types of graph query, such as where the path\n>> through the data is tight, and/or the query is written to prune bushy\n>> graphs, e.g. shortest path queries. The factor 10 should not be\n>> hardcoded in the planner, but should be settable, just as\n>> cursor_tuple_fraction is.\n> If you think this should be derived without parameters, then we would\n> want a function that starts at 1 for 1 input row and gets much larger\n> for larger input. The thinking here is that Graph OLTP is often a\n> shortest path between two nodes, whereas Graph Analytics and so the\n> worktable will get much bigger.\n\nOn the one hand, this smells like a planner hint. But on the other \nhand, it doesn't look like we will come up with proper graph-aware \nselectivity estimation system any time soon, so just having all graph \nOLTP queries suck until then because the planner hint is hardcoded \ndoesn't seem like a better solution. So I think this setting can be ok. \n I think the way you have characterized it makes sense, too: for graph \nOLAP, you want a larger value, for graph OLTP, you want a smaller value.Do you think there is a case to replace the 10x multiplier with \"recursive_worktable_estimate\" for total_rows calculation in the cost_recursive_union function too?","msg_date":"Fri, 28 Jan 2022 18:40:20 +0500","msg_from":"Hamid Akhtar <hamid.akhtar@gmail.com>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\n<peter.eisentraut@enterprisedb.com> wrote:\n> On the one hand, this smells like a planner hint. But on the other\n> hand, it doesn't look like we will come up with proper graph-aware\n> selectivity estimation system any time soon, so just having all graph\n> OLTP queries suck until then because the planner hint is hardcoded\n> doesn't seem like a better solution. So I think this setting can be ok.\n\nI agree. It's a bit lame, but seems pretty harmless, and I can't see\nus realistically doing a lot better with any reasonable amount of\nwork.\n\n-- \nRobert Haas\nEDB: http://www.enterprisedb.com\n\n\n","msg_date":"Fri, 28 Jan 2022 09:07:32 -0500","msg_from":"Robert Haas <robertmhaas@gmail.com>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Fri, 28 Jan 2022 at 14:07, Robert Haas <robertmhaas@gmail.com> wrote:\n>\n> On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\n> <peter.eisentraut@enterprisedb.com> wrote:\n> > On the one hand, this smells like a planner hint. But on the other\n> > hand, it doesn't look like we will come up with proper graph-aware\n> > selectivity estimation system any time soon, so just having all graph\n> > OLTP queries suck until then because the planner hint is hardcoded\n> > doesn't seem like a better solution. So I think this setting can be ok.\n>\n> I agree. It's a bit lame, but seems pretty harmless, and I can't see\n> us realistically doing a lot better with any reasonable amount of\n> work.\n\nShall I set this as Ready For Committer?\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/\n\n\n","msg_date":"Thu, 10 Mar 2022 17:42:14 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"Hi,\n\nOn 2022-03-10 17:42:14 +0000, Simon Riggs wrote:\n> Shall I set this as Ready For Committer?\n\nCurrently this CF entry fails on cfbot: https://cirrus-ci.com/task/4531771134967808?logs=test_world#L1158\n\n[16:27:35.772] # Failed test 'no parameters missing from postgresql.conf.sample'\n[16:27:35.772] # at t/003_check_guc.pl line 82.\n[16:27:35.772] # got: '1'\n[16:27:35.772] # expected: '0'\n[16:27:35.772] # Looks like you failed 1 test of 3.\n[16:27:35.772] [16:27:35] t/003_check_guc.pl ..............\n\nMarked as waiting on author.\n\n- Andres\n\n\n","msg_date":"Mon, 21 Mar 2022 17:04:54 -0700","msg_from":"Andres Freund <andres@anarazel.de>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Tue, 22 Mar 2022 at 00:04, Andres Freund <andres@anarazel.de> wrote:\n\n> On 2022-03-10 17:42:14 +0000, Simon Riggs wrote:\n> > Shall I set this as Ready For Committer?\n>\n> Currently this CF entry fails on cfbot: https://cirrus-ci.com/task/4531771134967808?logs=test_world#L1158\n>\n> [16:27:35.772] # Failed test 'no parameters missing from postgresql.conf.sample'\n> [16:27:35.772] # at t/003_check_guc.pl line 82.\n> [16:27:35.772] # got: '1'\n> [16:27:35.772] # expected: '0'\n> [16:27:35.772] # Looks like you failed 1 test of 3.\n> [16:27:35.772] [16:27:35] t/003_check_guc.pl ..............\n>\n> Marked as waiting on author.\n\nThanks.\n\nI've corrected that by adding a line to postgresql.conf.sample, as\nwell as adding docs.\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/","msg_date":"Wed, 23 Mar 2022 14:53:04 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"Robert Haas <robertmhaas@gmail.com> writes:\n> On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\n> <peter.eisentraut@enterprisedb.com> wrote:\n>> On the one hand, this smells like a planner hint. But on the other\n>> hand, it doesn't look like we will come up with proper graph-aware\n>> selectivity estimation system any time soon, so just having all graph\n>> OLTP queries suck until then because the planner hint is hardcoded\n>> doesn't seem like a better solution. So I think this setting can be ok.\n\n> I agree. It's a bit lame, but seems pretty harmless, and I can't see\n> us realistically doing a lot better with any reasonable amount of\n> work.\n\nYeah, agreed on all counts. The thing that makes it lame is that\nthere's no reason to expect that the same multiplier is good for\nevery recursive query done in an installation, or even in a session.\n\nOne could imagine dealing with that by adding custom syntax to WITH,\nas we have already done once:\n\nWITH RECURSIVE cte1 AS SCALE 1.0 (SELECT ...\n\nBut I *really* hesitate to go there, mainly because once we do\nsomething like that we can't ever undo it. I think Simon's\nproposal is a reasonable low-effort compromise.\n\nSome nitpicks:\n\n* The new calculation needs clamp_row_est(), since the float\nGUC could be fractional or even zero.\n\n* Do we want to prevent the GUC value from being zero? It's not\nvery sensible, plus I think we might want to reserve that value\nto mean \"use the built-in calculation\", in case we ever do put\nin some smarter logic here. But I'm not sure what a reasonable\nnon-zero lower bound would be.\n\n* The proposed docs claim that a smaller setting works by biasing\nthe planner towards fast-start plans, but I don't think I believe\nthat explanation. I'd venture that we want text more along the\nlines of \"This may help the planner choose the most appropriate\nmethod for joining the work table to the query's other tables\".\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 23 Mar 2022 13:36:29 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Wed, 23 Mar 2022 at 17:36, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>\n> Robert Haas <robertmhaas@gmail.com> writes:\n> > On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\n> > <peter.eisentraut@enterprisedb.com> wrote:\n> >> On the one hand, this smells like a planner hint. But on the other\n> >> hand, it doesn't look like we will come up with proper graph-aware\n> >> selectivity estimation system any time soon, so just having all graph\n> >> OLTP queries suck until then because the planner hint is hardcoded\n> >> doesn't seem like a better solution. So I think this setting can be ok.\n>\n> > I agree. It's a bit lame, but seems pretty harmless, and I can't see\n> > us realistically doing a lot better with any reasonable amount of\n> > work.\n>\n> Yeah, agreed on all counts. The thing that makes it lame is that\n> there's no reason to expect that the same multiplier is good for\n> every recursive query done in an installation, or even in a session.\n>\n> One could imagine dealing with that by adding custom syntax to WITH,\n> as we have already done once:\n>\n> WITH RECURSIVE cte1 AS SCALE 1.0 (SELECT ...\n>\n> But I *really* hesitate to go there, mainly because once we do\n> something like that we can't ever undo it. I think Simon's\n> proposal is a reasonable low-effort compromise.\n>\n> Some nitpicks:\n>\n> * The new calculation needs clamp_row_est(), since the float\n> GUC could be fractional or even zero.\n\nTrue, will do.\n\n> * Do we want to prevent the GUC value from being zero? It's not\n> very sensible, plus I think we might want to reserve that value\n> to mean \"use the built-in calculation\", in case we ever do put\n> in some smarter logic here. But I'm not sure what a reasonable\n> non-zero lower bound would be.\n\nAgreed, makes sense.\n\n> * The proposed docs claim that a smaller setting works by biasing\n> the planner towards fast-start plans, but I don't think I believe\n> that explanation. I'd venture that we want text more along the\n> lines of \"This may help the planner choose the most appropriate\n> method for joining the work table to the query's other tables\".\n\nOK, will improve.\n\n[New patch version pending]\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/\n\n\n","msg_date":"Wed, 23 Mar 2022 18:20:09 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Wed, 23 Mar 2022 at 18:20, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\n\n> [New patch version pending]\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/","msg_date":"Wed, 23 Mar 2022 19:37:02 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"Simon Riggs <simon.riggs@enterprisedb.com> writes:\n>> [New patch version pending]\n\nDo you have any objection if I rename the GUC to\nrecursive_worktable_factor? That seems a bit clearer as to what\nit does, and it leaves more room for other knobs in the same area\nif we decide we need any.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 23 Mar 2022 16:25:36 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>\n> Simon Riggs <simon.riggs@enterprisedb.com> writes:\n> >> [New patch version pending]\n>\n> Do you have any objection if I rename the GUC to\n> recursive_worktable_factor? That seems a bit clearer as to what\n> it does, and it leaves more room for other knobs in the same area\n> if we decide we need any.\n\nNone, I think your proposal is a better name.\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/\n\n\n","msg_date":"Thu, 24 Mar 2022 10:32:00 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"Simon Riggs <simon.riggs@enterprisedb.com> writes:\n> On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>> Do you have any objection if I rename the GUC to\n>> recursive_worktable_factor? That seems a bit clearer as to what\n>> it does, and it leaves more room for other knobs in the same area\n>> if we decide we need any.\n\n> None, I think your proposal is a better name.\n\nPushed that way.\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Thu, 24 Mar 2022 11:48:21 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: Parameter for planner estimate of recursive queries"},{"msg_contents":"On Thu, 24 Mar 2022 at 15:48, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n>\n> Simon Riggs <simon.riggs@enterprisedb.com> writes:\n> > On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\n> >> Do you have any objection if I rename the GUC to\n> >> recursive_worktable_factor? That seems a bit clearer as to what\n> >> it does, and it leaves more room for other knobs in the same area\n> >> if we decide we need any.\n>\n> > None, I think your proposal is a better name.\n>\n> Pushed that way.\n\nOk, thanks.\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/\n\n\n","msg_date":"Thu, 24 Mar 2022 16:04:55 +0000","msg_from":"Simon Riggs <simon.riggs@enterprisedb.com>","msg_from_op":true,"msg_subject":"Re: Parameter for planner estimate of recursive queries"}],"string":"[\n {\n \"msg_contents\": \"I've been investigating the poor performance of a WITH RECURSIVE\\nquery, which I've recreated with test data.\\n\\nThe first thing was to re-write the query, which helped improve\\nperformance by about 30%, but the plan was still very bad. With a\\nsmall patch I've been able to improve performance by about x100.\\n\\nThe poor performance is traced to the planner cost estimates for\\nrecursive queries. Specifically, the cost of the recursive arm of the\\nquery is evaluated based upon both of these hardcoded assumptions:\\n\\n1. The recursion will last for 10 loops\\n2. The average size of the worktable will be 10x the size of the\\ninitial query (non-recursive term).\\n\\nTaken together these assumptions lead to a very poor estimate of the\\nworktable activity (in this case), which leads to the plan changing as\\na result.\\n\\nThe factor 10 is a reasonably safe assumption and helps avoid worst\\ncase behavior in bigger graph queries. However, the factor 10 is way\\ntoo large for many types of graph query, such as where the path\\nthrough the data is tight, and/or the query is written to prune bushy\\ngraphs, e.g. shortest path queries. The factor 10 should not be\\nhardcoded in the planner, but should be settable, just as\\ncursor_tuple_fraction is.\\n\\nI've written a short patch to make the estimate of the avg size of the\\nworktable configurable:\\n\\n recursive_worktable_estimate = N (default 10)\\n\\nUsing this parameter with the test query results in a consistently\\nrepeatable ~100x gain in performance, using\\nrecursive_worktable_estimate = 1 for a shortest path query:\\n\\nUnpatched: 1775ms\\nPatched: 17.2ms\\n\\nThis is because the estimated size of the worktable is closer to the\\ntruth and so leads naturally to a more sensible plan. EXPLAINs\\nattached - please look at the estimated rows for the WorkTable Scan.\\n\\nThere are various options for setting the two estimates: just one, or\\nother, or both values separately, or both together. Note that I\\nhaven't touched the estimate that recursion will last for 10 loops. I\\nfigured that people would object to two knobs.\\n\\nThoughts?\\n\\n\\nThere are 2 other ways to speed up the query. One is to set\\nenable_seqscan = off, which helps about 20%, but may have other\\nconsequences. Two is to set work_mem = 512MB, so that the poor plan\\n(hash) works as fast as possible, but that is far from optimal either.\\nGetting the right plan is x20 faster than either of those\\nalternatives.\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\",\n \"msg_date\": \"Wed, 27 Oct 2021 15:58:58 +0100\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\\n\\n> The poor performance is traced to the planner cost estimates for\\n> recursive queries. Specifically, the cost of the recursive arm of the\\n> query is evaluated based upon both of these hardcoded assumptions:\\n>\\n> 1. The recursion will last for 10 loops\\n> 2. The average size of the worktable will be 10x the size of the\\n> initial query (non-recursive term).\\n>\\n> Taken together these assumptions lead to a very poor estimate of the\\n> worktable activity (in this case), which leads to the plan changing as\\n> a result.\\n>\\n> The factor 10 is a reasonably safe assumption and helps avoid worst\\n> case behavior in bigger graph queries. However, the factor 10 is way\\n> too large for many types of graph query, such as where the path\\n> through the data is tight, and/or the query is written to prune bushy\\n> graphs, e.g. shortest path queries. The factor 10 should not be\\n> hardcoded in the planner, but should be settable, just as\\n> cursor_tuple_fraction is.\\n\\nIf you think this should be derived without parameters, then we would\\nwant a function that starts at 1 for 1 input row and gets much larger\\nfor larger input. The thinking here is that Graph OLTP is often a\\nshortest path between two nodes, whereas Graph Analytics and so the\\nworktable will get much bigger.\\n\\nSo I'm, thinking we use\\n\\nrel->tuples = min(1, cte_rows * cte_rows/2);\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Fri, 31 Dec 2021 14:10:12 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"> The factor 10 should not be hardcoded in the planner, but should be\\nsettable, just as cursor_tuple_fraction is.\\n\\nI feel considerably out of my depth here, but I like the idea of a working\\ntable size multiplier GUC, given the challenges of predicting the number of\\niterations (and any adjustments to cardinality per iteration). An\\nexponential cost function may lead to increasingly pathological outcomes,\\nespecially when estimates for cte_rows are off.\\n\\nIn the EXPLAINs, it looked like the estimates for knows_pkey were off by an\\norder of magnitude or so. It's possible the planner would have chosen the\\nNested Loop plan if knows_pkey had estimated to rows=87 (as the WindowAgg\\nwould have estimated to roughly the same size as the second plan anyways,\\neven with rel->tuples = 10 * cte_rows).\\n\\nI also wonder if there's a better default than cte_rows * 10, but\\nimplementing a new GUC sounds like a reasonable solution to this as well.\\n\\n--\\n\\nKenaniah\\n\\nOn Sat, Jan 22, 2022 at 1:58 PM Simon Riggs <simon.riggs@enterprisedb.com>\\nwrote:\\n\\n> On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com>\\n> wrote:\\n>\\n> > The poor performance is traced to the planner cost estimates for\\n> > recursive queries. Specifically, the cost of the recursive arm of the\\n> > query is evaluated based upon both of these hardcoded assumptions:\\n> >\\n> > 1. The recursion will last for 10 loops\\n> > 2. The average size of the worktable will be 10x the size of the\\n> > initial query (non-recursive term).\\n> >\\n> > Taken together these assumptions lead to a very poor estimate of the\\n> > worktable activity (in this case), which leads to the plan changing as\\n> > a result.\\n> >\\n> > The factor 10 is a reasonably safe assumption and helps avoid worst\\n> > case behavior in bigger graph queries. However, the factor 10 is way\\n> > too large for many types of graph query, such as where the path\\n> > through the data is tight, and/or the query is written to prune bushy\\n> > graphs, e.g. shortest path queries. The factor 10 should not be\\n> > hardcoded in the planner, but should be settable, just as\\n> > cursor_tuple_fraction is.\\n>\\n> If you think this should be derived without parameters, then we would\\n> want a function that starts at 1 for 1 input row and gets much larger\\n> for larger input. The thinking here is that Graph OLTP is often a\\n> shortest path between two nodes, whereas Graph Analytics and so the\\n> worktable will get much bigger.\\n>\\n> So I'm, thinking we use\\n>\\n> rel->tuples = min(1, cte_rows * cte_rows/2);\\n>\\n> --\\n> Simon Riggs http://www.EnterpriseDB.com/\\n>\\n>\\n>\\n>\\n>\\n\\n> The factor 10 should not be hardcoded in the planner, but should be settable, just as cursor_tuple_fraction is.I feel considerably out of my depth here, but I like the idea of a working table size multiplier GUC, given the challenges of predicting the number of iterations (and any adjustments to cardinality per iteration). An exponential cost function may lead to increasingly pathological outcomes, especially when estimates for cte_rows are off. In the EXPLAINs, it looked like the estimates for knows_pkey were off by an order of magnitude or so. It's possible the planner would have chosen the Nested Loop plan if knows_pkey had estimated to rows=87 (as the WindowAgg would have estimated to roughly the same size as the second plan anyways, even with rel->tuples = 10 * cte_rows).I also wonder if there's a better default than cte_rows * 10, but implementing a new GUC sounds like a reasonable solution to this as well.--KenaniahOn Sat, Jan 22, 2022 at 1:58 PM Simon Riggs <simon.riggs@enterprisedb.com> wrote:On Wed, 27 Oct 2021 at 15:58, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\\n\\n> The poor performance is traced to the planner cost estimates for\\n> recursive queries. Specifically, the cost of the recursive arm of the\\n> query is evaluated based upon both of these hardcoded assumptions:\\n>\\n> 1. The recursion will last for 10 loops\\n> 2. The average size of the worktable will be 10x the size of the\\n> initial query (non-recursive term).\\n>\\n> Taken together these assumptions lead to a very poor estimate of the\\n> worktable activity (in this case), which leads to the plan changing as\\n> a result.\\n>\\n> The factor 10 is a reasonably safe assumption and helps avoid worst\\n> case behavior in bigger graph queries. However, the factor 10 is way\\n> too large for many types of graph query, such as where the path\\n> through the data is tight, and/or the query is written to prune bushy\\n> graphs, e.g. shortest path queries. The factor 10 should not be\\n> hardcoded in the planner, but should be settable, just as\\n> cursor_tuple_fraction is.\\n\\nIf you think this should be derived without parameters, then we would\\nwant a function that starts at 1 for 1 input row and gets much larger\\nfor larger input. The thinking here is that Graph OLTP is often a\\nshortest path between two nodes, whereas Graph Analytics and so the\\nworktable will get much bigger.\\n\\nSo I'm, thinking we use\\n\\nrel->tuples = min(1, cte_rows * cte_rows/2);\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\",\n \"msg_date\": \"Sat, 22 Jan 2022 14:33:59 -0800\",\n \"msg_from\": \"Kenaniah Cerny <kenaniah@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On 31.12.21 15:10, Simon Riggs wrote:\\n>> The factor 10 is a reasonably safe assumption and helps avoid worst\\n>> case behavior in bigger graph queries. However, the factor 10 is way\\n>> too large for many types of graph query, such as where the path\\n>> through the data is tight, and/or the query is written to prune bushy\\n>> graphs, e.g. shortest path queries. The factor 10 should not be\\n>> hardcoded in the planner, but should be settable, just as\\n>> cursor_tuple_fraction is.\\n> If you think this should be derived without parameters, then we would\\n> want a function that starts at 1 for 1 input row and gets much larger\\n> for larger input. The thinking here is that Graph OLTP is often a\\n> shortest path between two nodes, whereas Graph Analytics and so the\\n> worktable will get much bigger.\\n\\nOn the one hand, this smells like a planner hint. But on the other \\nhand, it doesn't look like we will come up with proper graph-aware \\nselectivity estimation system any time soon, so just having all graph \\nOLTP queries suck until then because the planner hint is hardcoded \\ndoesn't seem like a better solution. So I think this setting can be ok. \\n I think the way you have characterized it makes sense, too: for graph \\nOLAP, you want a larger value, for graph OLTP, you want a smaller value.\\n\\n\\n\\n\",\n \"msg_date\": \"Tue, 25 Jan 2022 10:44:21 +0100\",\n \"msg_from\": \"Peter Eisentraut <peter.eisentraut@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Tue, 25 Jan 2022 at 14:44, Peter Eisentraut <\\npeter.eisentraut@enterprisedb.com> wrote:\\n\\n> On 31.12.21 15:10, Simon Riggs wrote:\\n> >> The factor 10 is a reasonably safe assumption and helps avoid worst\\n> >> case behavior in bigger graph queries. However, the factor 10 is way\\n> >> too large for many types of graph query, such as where the path\\n> >> through the data is tight, and/or the query is written to prune bushy\\n> >> graphs, e.g. shortest path queries. The factor 10 should not be\\n> >> hardcoded in the planner, but should be settable, just as\\n> >> cursor_tuple_fraction is.\\n> > If you think this should be derived without parameters, then we would\\n> > want a function that starts at 1 for 1 input row and gets much larger\\n> > for larger input. The thinking here is that Graph OLTP is often a\\n> > shortest path between two nodes, whereas Graph Analytics and so the\\n> > worktable will get much bigger.\\n>\\n> On the one hand, this smells like a planner hint. But on the other\\n> hand, it doesn't look like we will come up with proper graph-aware\\n> selectivity estimation system any time soon, so just having all graph\\n> OLTP queries suck until then because the planner hint is hardcoded\\n> doesn't seem like a better solution. So I think this setting can be ok.\\n> I think the way you have characterized it makes sense, too: for graph\\n> OLAP, you want a larger value, for graph OLTP, you want a smaller value.\\n>\\n\\nDo you think there is a case to replace the 10x multiplier with\\n\\\"recursive_worktable_estimate\\\" for total_rows calculation in the\\ncost_recursive_union function too?\\n\\nOn Tue, 25 Jan 2022 at 14:44, Peter Eisentraut <peter.eisentraut@enterprisedb.com> wrote:On 31.12.21 15:10, Simon Riggs wrote:\\n>> The factor 10 is a reasonably safe assumption and helps avoid worst\\n>> case behavior in bigger graph queries. However, the factor 10 is way\\n>> too large for many types of graph query, such as where the path\\n>> through the data is tight, and/or the query is written to prune bushy\\n>> graphs, e.g. shortest path queries. The factor 10 should not be\\n>> hardcoded in the planner, but should be settable, just as\\n>> cursor_tuple_fraction is.\\n> If you think this should be derived without parameters, then we would\\n> want a function that starts at 1 for 1 input row and gets much larger\\n> for larger input. The thinking here is that Graph OLTP is often a\\n> shortest path between two nodes, whereas Graph Analytics and so the\\n> worktable will get much bigger.\\n\\nOn the one hand, this smells like a planner hint. But on the other \\nhand, it doesn't look like we will come up with proper graph-aware \\nselectivity estimation system any time soon, so just having all graph \\nOLTP queries suck until then because the planner hint is hardcoded \\ndoesn't seem like a better solution. So I think this setting can be ok. \\n I think the way you have characterized it makes sense, too: for graph \\nOLAP, you want a larger value, for graph OLTP, you want a smaller value.Do you think there is a case to replace the 10x multiplier with \\\"recursive_worktable_estimate\\\" for total_rows calculation in the cost_recursive_union function too?\",\n \"msg_date\": \"Fri, 28 Jan 2022 18:40:20 +0500\",\n \"msg_from\": \"Hamid Akhtar <hamid.akhtar@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\\n<peter.eisentraut@enterprisedb.com> wrote:\\n> On the one hand, this smells like a planner hint. But on the other\\n> hand, it doesn't look like we will come up with proper graph-aware\\n> selectivity estimation system any time soon, so just having all graph\\n> OLTP queries suck until then because the planner hint is hardcoded\\n> doesn't seem like a better solution. So I think this setting can be ok.\\n\\nI agree. It's a bit lame, but seems pretty harmless, and I can't see\\nus realistically doing a lot better with any reasonable amount of\\nwork.\\n\\n-- \\nRobert Haas\\nEDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 28 Jan 2022 09:07:32 -0500\",\n \"msg_from\": \"Robert Haas <robertmhaas@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Fri, 28 Jan 2022 at 14:07, Robert Haas <robertmhaas@gmail.com> wrote:\\n>\\n> On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\\n> <peter.eisentraut@enterprisedb.com> wrote:\\n> > On the one hand, this smells like a planner hint. But on the other\\n> > hand, it doesn't look like we will come up with proper graph-aware\\n> > selectivity estimation system any time soon, so just having all graph\\n> > OLTP queries suck until then because the planner hint is hardcoded\\n> > doesn't seem like a better solution. So I think this setting can be ok.\\n>\\n> I agree. It's a bit lame, but seems pretty harmless, and I can't see\\n> us realistically doing a lot better with any reasonable amount of\\n> work.\\n\\nShall I set this as Ready For Committer?\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Thu, 10 Mar 2022 17:42:14 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2022-03-10 17:42:14 +0000, Simon Riggs wrote:\\n> Shall I set this as Ready For Committer?\\n\\nCurrently this CF entry fails on cfbot: https://cirrus-ci.com/task/4531771134967808?logs=test_world#L1158\\n\\n[16:27:35.772] # Failed test 'no parameters missing from postgresql.conf.sample'\\n[16:27:35.772] # at t/003_check_guc.pl line 82.\\n[16:27:35.772] # got: '1'\\n[16:27:35.772] # expected: '0'\\n[16:27:35.772] # Looks like you failed 1 test of 3.\\n[16:27:35.772] [16:27:35] t/003_check_guc.pl ..............\\n\\nMarked as waiting on author.\\n\\n- Andres\\n\\n\\n\",\n \"msg_date\": \"Mon, 21 Mar 2022 17:04:54 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Tue, 22 Mar 2022 at 00:04, Andres Freund <andres@anarazel.de> wrote:\\n\\n> On 2022-03-10 17:42:14 +0000, Simon Riggs wrote:\\n> > Shall I set this as Ready For Committer?\\n>\\n> Currently this CF entry fails on cfbot: https://cirrus-ci.com/task/4531771134967808?logs=test_world#L1158\\n>\\n> [16:27:35.772] # Failed test 'no parameters missing from postgresql.conf.sample'\\n> [16:27:35.772] # at t/003_check_guc.pl line 82.\\n> [16:27:35.772] # got: '1'\\n> [16:27:35.772] # expected: '0'\\n> [16:27:35.772] # Looks like you failed 1 test of 3.\\n> [16:27:35.772] [16:27:35] t/003_check_guc.pl ..............\\n>\\n> Marked as waiting on author.\\n\\nThanks.\\n\\nI've corrected that by adding a line to postgresql.conf.sample, as\\nwell as adding docs.\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\",\n \"msg_date\": \"Wed, 23 Mar 2022 14:53:04 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"Robert Haas <robertmhaas@gmail.com> writes:\\n> On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\\n> <peter.eisentraut@enterprisedb.com> wrote:\\n>> On the one hand, this smells like a planner hint. But on the other\\n>> hand, it doesn't look like we will come up with proper graph-aware\\n>> selectivity estimation system any time soon, so just having all graph\\n>> OLTP queries suck until then because the planner hint is hardcoded\\n>> doesn't seem like a better solution. So I think this setting can be ok.\\n\\n> I agree. It's a bit lame, but seems pretty harmless, and I can't see\\n> us realistically doing a lot better with any reasonable amount of\\n> work.\\n\\nYeah, agreed on all counts. The thing that makes it lame is that\\nthere's no reason to expect that the same multiplier is good for\\nevery recursive query done in an installation, or even in a session.\\n\\nOne could imagine dealing with that by adding custom syntax to WITH,\\nas we have already done once:\\n\\nWITH RECURSIVE cte1 AS SCALE 1.0 (SELECT ...\\n\\nBut I *really* hesitate to go there, mainly because once we do\\nsomething like that we can't ever undo it. I think Simon's\\nproposal is a reasonable low-effort compromise.\\n\\nSome nitpicks:\\n\\n* The new calculation needs clamp_row_est(), since the float\\nGUC could be fractional or even zero.\\n\\n* Do we want to prevent the GUC value from being zero? It's not\\nvery sensible, plus I think we might want to reserve that value\\nto mean \\\"use the built-in calculation\\\", in case we ever do put\\nin some smarter logic here. But I'm not sure what a reasonable\\nnon-zero lower bound would be.\\n\\n* The proposed docs claim that a smaller setting works by biasing\\nthe planner towards fast-start plans, but I don't think I believe\\nthat explanation. I'd venture that we want text more along the\\nlines of \\\"This may help the planner choose the most appropriate\\nmethod for joining the work table to the query's other tables\\\".\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 13:36:29 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Wed, 23 Mar 2022 at 17:36, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>\\n> Robert Haas <robertmhaas@gmail.com> writes:\\n> > On Tue, Jan 25, 2022 at 4:44 AM Peter Eisentraut\\n> > <peter.eisentraut@enterprisedb.com> wrote:\\n> >> On the one hand, this smells like a planner hint. But on the other\\n> >> hand, it doesn't look like we will come up with proper graph-aware\\n> >> selectivity estimation system any time soon, so just having all graph\\n> >> OLTP queries suck until then because the planner hint is hardcoded\\n> >> doesn't seem like a better solution. So I think this setting can be ok.\\n>\\n> > I agree. It's a bit lame, but seems pretty harmless, and I can't see\\n> > us realistically doing a lot better with any reasonable amount of\\n> > work.\\n>\\n> Yeah, agreed on all counts. The thing that makes it lame is that\\n> there's no reason to expect that the same multiplier is good for\\n> every recursive query done in an installation, or even in a session.\\n>\\n> One could imagine dealing with that by adding custom syntax to WITH,\\n> as we have already done once:\\n>\\n> WITH RECURSIVE cte1 AS SCALE 1.0 (SELECT ...\\n>\\n> But I *really* hesitate to go there, mainly because once we do\\n> something like that we can't ever undo it. I think Simon's\\n> proposal is a reasonable low-effort compromise.\\n>\\n> Some nitpicks:\\n>\\n> * The new calculation needs clamp_row_est(), since the float\\n> GUC could be fractional or even zero.\\n\\nTrue, will do.\\n\\n> * Do we want to prevent the GUC value from being zero? It's not\\n> very sensible, plus I think we might want to reserve that value\\n> to mean \\\"use the built-in calculation\\\", in case we ever do put\\n> in some smarter logic here. But I'm not sure what a reasonable\\n> non-zero lower bound would be.\\n\\nAgreed, makes sense.\\n\\n> * The proposed docs claim that a smaller setting works by biasing\\n> the planner towards fast-start plans, but I don't think I believe\\n> that explanation. I'd venture that we want text more along the\\n> lines of \\\"This may help the planner choose the most appropriate\\n> method for joining the work table to the query's other tables\\\".\\n\\nOK, will improve.\\n\\n[New patch version pending]\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 18:20:09 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Wed, 23 Mar 2022 at 18:20, Simon Riggs <simon.riggs@enterprisedb.com> wrote:\\n\\n> [New patch version pending]\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\",\n \"msg_date\": \"Wed, 23 Mar 2022 19:37:02 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"Simon Riggs <simon.riggs@enterprisedb.com> writes:\\n>> [New patch version pending]\\n\\nDo you have any objection if I rename the GUC to\\nrecursive_worktable_factor? That seems a bit clearer as to what\\nit does, and it leaves more room for other knobs in the same area\\nif we decide we need any.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 23 Mar 2022 16:25:36 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>\\n> Simon Riggs <simon.riggs@enterprisedb.com> writes:\\n> >> [New patch version pending]\\n>\\n> Do you have any objection if I rename the GUC to\\n> recursive_worktable_factor? That seems a bit clearer as to what\\n> it does, and it leaves more room for other knobs in the same area\\n> if we decide we need any.\\n\\nNone, I think your proposal is a better name.\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 10:32:00 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"Simon Riggs <simon.riggs@enterprisedb.com> writes:\\n> On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> Do you have any objection if I rename the GUC to\\n>> recursive_worktable_factor? That seems a bit clearer as to what\\n>> it does, and it leaves more room for other knobs in the same area\\n>> if we decide we need any.\\n\\n> None, I think your proposal is a better name.\\n\\nPushed that way.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 11:48:21 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n },\n {\n \"msg_contents\": \"On Thu, 24 Mar 2022 at 15:48, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>\\n> Simon Riggs <simon.riggs@enterprisedb.com> writes:\\n> > On Wed, 23 Mar 2022 at 20:25, Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> >> Do you have any objection if I rename the GUC to\\n> >> recursive_worktable_factor? That seems a bit clearer as to what\\n> >> it does, and it leaves more room for other knobs in the same area\\n> >> if we decide we need any.\\n>\\n> > None, I think your proposal is a better name.\\n>\\n> Pushed that way.\\n\\nOk, thanks.\\n\\n-- \\nSimon Riggs http://www.EnterpriseDB.com/\\n\\n\\n\",\n \"msg_date\": \"Thu, 24 Mar 2022 16:04:55 +0000\",\n \"msg_from\": \"Simon Riggs <simon.riggs@enterprisedb.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Parameter for planner estimate of recursive queries\"\n }\n]","isConversational":false}}},{"rowIdx":52999,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi,\n\nIs there a specific reason that we have a generic WARNING \"worker took\ntoo long to start; canceled\" for an autovacuum worker? Isn't it better\nwith \"autovacuum worker took too long to start; canceled\"? It is\nconfusing to see the generic message in the server logs while\ndebugging an issue for a user who doesn't know the internals of\nautovacuum code.\n\nTo be more informative about the message, how about the following:\n1) ereport(WARNING,\n (errmsg( \"worker took too long to start\"),\n errdetail(\"Previous attempt to start autovacuum\nworker was failed, canceled.\")));\nor\n2) ereport(WARNING,\n (errmsg( \"worker took too long to start, canceled\"),\n errdetail(\"The postmaster couldn't start an\nautovacuum worker.\")));\nor\n3) ereport(WARNING,\n (errmsg( \"worker took too long to start, canceled\"),\n errdetail(\"Previous attempt to start autovacuum\nworker was failed.\")));\nor\n4) elog(WARNING, \"postmaster couldn't start an autovacuum worker\");\n\nThoughts?\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Wed, 27 Oct 2021 21:56:37 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":true,"msg_subject":"Isn't it better with \"autovacuum worker....\" instead of \"worker took\n too long to start; canceled\" specific to \"auto"},{"msg_contents":"On 10/27/21, 9:29 AM, \"Bharath Rupireddy\" <bharath.rupireddyforpostgres@gmail.com> wrote:\r\n> Is there a specific reason that we have a generic WARNING \"worker took\r\n> too long to start; canceled\" for an autovacuum worker? Isn't it better\r\n> with \"autovacuum worker took too long to start; canceled\"? It is\r\n> confusing to see the generic message in the server logs while\r\n> debugging an issue for a user who doesn't know the internals of\r\n> autovacuum code.\r\n\r\nIt looks like it has been this way for a while [0]. I don't know if\r\nI've ever seen this message before, and from the comments near it, it\r\nsounds like it is expected to rarely happen.\r\n\r\n> To be more informative about the message, how about the following:\r\n\r\nMy vote is to just change it to\r\n\r\n ereport(WARNING,\r\n (errmsg(\"autovacuum worker took too long to start; canceled\")));\r\n\r\nand call it a day. If we wanted to add errdetail(), I think we should\r\nmake sure it is providing useful context, but I'm not sure what that\r\nmight look like.\r\n\r\nNathan\r\n\r\n[0] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=bae0b56\r\n\r\n","msg_date":"Wed, 27 Oct 2021 19:05:10 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too\n long to start; canceled\" specific to \"auto"},{"msg_contents":"On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\n> On 10/27/21, 9:29 AM, \"Bharath Rupireddy\" <bharath.rupireddyforpostgres@gmail.com> wrote:\n> > Is there a specific reason that we have a generic WARNING \"worker took\n> > too long to start; canceled\" for an autovacuum worker? Isn't it better\n> > with \"autovacuum worker took too long to start; canceled\"? It is\n> > confusing to see the generic message in the server logs while\n> > debugging an issue for a user who doesn't know the internals of\n> > autovacuum code.\n> \n> It looks like it has been this way for a while [0]. I don't know if\n> I've ever seen this message before, and from the comments near it, it\n> sounds like it is expected to rarely happen.\n\nI was surprised to see that I have only two logs for this in the last 8 weeks.\n\n> > To be more informative about the message, how about the following:\n> \n> My vote is to just change it to\n> \n> ereport(WARNING,\n> (errmsg(\"autovacuum worker took too long to start; canceled\")));\n> \n> and call it a day. If we wanted to add errdetail(), I think we should\n> make sure it is providing useful context, but I'm not sure what that\n> might look like.\n\nI think that's fine.\n\nNote that the backend_type is illuminating for those who use CSV logs, or use\nP13+ and log_line_prefix += %b (see 70a7b4776).\n\nsession_line | 1\nerror_severity | WARNING\nmessage | worker took too long to start; canceled\nbackend_type | autovacuum launcher\n\n-- \nJustin\n\n\n","msg_date":"Wed, 27 Oct 2021 14:26:11 -0500","msg_from":"Justin Pryzby <pryzby@telsasoft.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"},{"msg_contents":"At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in \n> On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\n> > My vote is to just change it to\n> > \n> > ereport(WARNING,\n> > (errmsg(\"autovacuum worker took too long to start; canceled\")));\n> > \n> > and call it a day. If we wanted to add errdetail(), I think we should\n> > make sure it is providing useful context, but I'm not sure what that\n> > might look like.\n> \n> I think that's fine.\n\n+1\n\n> Note that the backend_type is illuminating for those who use CSV logs, or use\n> P13+ and log_line_prefix += %b (see 70a7b4776).\n> \n> session_line | 1\n> error_severity | WARNING\n> message | worker took too long to start; canceled\n> backend_type | autovacuum launcher\n\nYeah, the additional \"autovacuum\" is not noisy at all even in that\ncontext. Some other messages are prefixed with \"autovacuum\".\n\n \"could not fork autovacuum worker process: %m\"\n \"autovacuum worker started without a worker entry\"\n\nBy a quick look all occurances of \"laucher\" are prefixed with\n\"autovacuum\" or \"logical replcaion\", which seems fine.\n\nAs a related topic, autovacuum.c has another use of bare \"worker\"s.\n\n>\ttmpcxt = AllocSetContextCreate(CurrentMemoryContext,\n>\t\t\t\t\t\t\t\t \"Start worker tmp cxt\",\n>\t\t\t\t\t\t\t\t ALLOCSET_DEFAULT_SIZES);\n\n>\tAutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\n>\t\t\t\t\t\t\t\t\t\t \"AV worker\",\n>\t\t\t\t\t\t\t\t\t\t ALLOCSET_DEFAULT_SIZES);\n\nI'm not sure the former needs to be fixed, but the latter is actually\nvisible to users via pg_log_backend_memory_contexts().\n\nLOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\n\nregards.\n\n-- \nKyotaro Horiguchi\nNTT Open Source Software Center\n\n\n","msg_date":"Thu, 28 Oct 2021 10:41:43 +0900 (JST)","msg_from":"Kyotaro Horiguchi <horikyota.ntt@gmail.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of\n \"worker took too long to start; canceled\" specific to \"auto"},{"msg_contents":"On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\n<horikyota.ntt@gmail.com> wrote:\n>\n> At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\n> > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\n> > > My vote is to just change it to\n> > >\n> > > ereport(WARNING,\n> > > (errmsg(\"autovacuum worker took too long to start; canceled\")));\n> > >\n> > > and call it a day. If we wanted to add errdetail(), I think we should\n> > > make sure it is providing useful context, but I'm not sure what that\n> > > might look like.\n> >\n> > I think that's fine.\n>\n> +1\n\nDone.\n\n> > Note that the backend_type is illuminating for those who use CSV logs, or use\n> > P13+ and log_line_prefix += %b (see 70a7b4776).\n> >\n> > session_line | 1\n> > error_severity | WARNING\n> > message | worker took too long to start; canceled\n> > backend_type | autovacuum launcher\n>\n> Yeah, the additional \"autovacuum\" is not noisy at all even in that\n> context. Some other messages are prefixed with \"autovacuum\".\n>\n> \"could not fork autovacuum worker process: %m\"\n> \"autovacuum worker started without a worker entry\"\n>\n> By a quick look all occurances of \"laucher\" are prefixed with\n> \"autovacuum\" or \"logical replcaion\", which seems fine.\n>\n> As a related topic, autovacuum.c has another use of bare \"worker\"s.\n>\n> > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\n> > \"Start worker tmp cxt\",\n> > ALLOCSET_DEFAULT_SIZES);\n>\n> > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\n> > \"AV worker\",\n> > ALLOCSET_DEFAULT_SIZES);\n>\n> I'm not sure the former needs to be fixed, but the latter is actually\n> visible to users via pg_log_backend_memory_contexts().\n>\n> LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\n\nGood catch. I've seen the use of \"AV\" in some of the mem context\nnames, why that? Let's be specific and say \"Autovacuum\". Attached\npatch does that. Please review it.\n\nRegards,\nBharath Rupireddy.","msg_date":"Thu, 28 Oct 2021 08:13:58 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":true,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"},{"msg_contents":"On Thu, Oct 28, 2021 at 8:14 AM Bharath Rupireddy\n<bharath.rupireddyforpostgres@gmail.com> wrote:\n>\n> > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\n>\n> Good catch. I've seen the use of \"AV\" in some of the mem context\n> names, why that? Let's be specific and say \"Autovacuum\". Attached\n> patch does that. Please review it.\n\n+1, the error message and other improvements look good.\n\n-- \nRegards,\nDilip Kumar\nEnterpriseDB: http://www.enterprisedb.com\n\n\n","msg_date":"Thu, 28 Oct 2021 09:52:19 +0530","msg_from":"Dilip Kumar <dilipbalaut@gmail.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"},{"msg_contents":"On Thu, Oct 28, 2021 at 11:44 AM Bharath Rupireddy\n<bharath.rupireddyforpostgres@gmail.com> wrote:\n>\n> On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\n> <horikyota.ntt@gmail.com> wrote:\n> >\n> > At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\n> > > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\n> > > > My vote is to just change it to\n> > > >\n> > > > ereport(WARNING,\n> > > > (errmsg(\"autovacuum worker took too long to start; canceled\")));\n> > > >\n> > > > and call it a day. If we wanted to add errdetail(), I think we should\n> > > > make sure it is providing useful context, but I'm not sure what that\n> > > > might look like.\n> > >\n> > > I think that's fine.\n> >\n> > +1\n>\n> Done.\n>\n> > > Note that the backend_type is illuminating for those who use CSV logs, or use\n> > > P13+ and log_line_prefix += %b (see 70a7b4776).\n> > >\n> > > session_line | 1\n> > > error_severity | WARNING\n> > > message | worker took too long to start; canceled\n> > > backend_type | autovacuum launcher\n> >\n> > Yeah, the additional \"autovacuum\" is not noisy at all even in that\n> > context. Some other messages are prefixed with \"autovacuum\".\n> >\n> > \"could not fork autovacuum worker process: %m\"\n> > \"autovacuum worker started without a worker entry\"\n> >\n> > By a quick look all occurances of \"laucher\" are prefixed with\n> > \"autovacuum\" or \"logical replcaion\", which seems fine.\n> >\n> > As a related topic, autovacuum.c has another use of bare \"worker\"s.\n> >\n> > > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\n> > > \"Start worker tmp cxt\",\n> > > ALLOCSET_DEFAULT_SIZES);\n> >\n> > > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\n> > > \"AV worker\",\n> > > ALLOCSET_DEFAULT_SIZES);\n> >\n> > I'm not sure the former needs to be fixed, but the latter is actually\n> > visible to users via pg_log_backend_memory_contexts().\n> >\n> > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\n>\n> Good catch. I've seen the use of \"AV\" in some of the mem context\n> names, why that? Let's be specific and say \"Autovacuum\". Attached\n> patch does that. Please review it.\n\n+1. The patch looks good to me too.\n\nRegards,\n\n-- \nMasahiko Sawada\nEDB: https://www.enterprisedb.com/\n\n\n","msg_date":"Thu, 28 Oct 2021 16:11:16 +0900","msg_from":"Masahiko Sawada <sawada.mshk@gmail.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"},{"msg_contents":"On Thu, Oct 28, 2021 at 12:41 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\n>\n> On Thu, Oct 28, 2021 at 11:44 AM Bharath Rupireddy\n> <bharath.rupireddyforpostgres@gmail.com> wrote:\n> >\n> > On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\n> > <horikyota.ntt@gmail.com> wrote:\n> > >\n> > > At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\n> > > > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\n> > > > > My vote is to just change it to\n> > > > >\n> > > > > ereport(WARNING,\n> > > > > (errmsg(\"autovacuum worker took too long to start; canceled\")));\n> > > > >\n> > > > > and call it a day. If we wanted to add errdetail(), I think we should\n> > > > > make sure it is providing useful context, but I'm not sure what that\n> > > > > might look like.\n> > > >\n> > > > I think that's fine.\n> > >\n> > > +1\n> >\n> > Done.\n> >\n> > > > Note that the backend_type is illuminating for those who use CSV logs, or use\n> > > > P13+ and log_line_prefix += %b (see 70a7b4776).\n> > > >\n> > > > session_line | 1\n> > > > error_severity | WARNING\n> > > > message | worker took too long to start; canceled\n> > > > backend_type | autovacuum launcher\n> > >\n> > > Yeah, the additional \"autovacuum\" is not noisy at all even in that\n> > > context. Some other messages are prefixed with \"autovacuum\".\n> > >\n> > > \"could not fork autovacuum worker process: %m\"\n> > > \"autovacuum worker started without a worker entry\"\n> > >\n> > > By a quick look all occurances of \"laucher\" are prefixed with\n> > > \"autovacuum\" or \"logical replcaion\", which seems fine.\n> > >\n> > > As a related topic, autovacuum.c has another use of bare \"worker\"s.\n> > >\n> > > > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\n> > > > \"Start worker tmp cxt\",\n> > > > ALLOCSET_DEFAULT_SIZES);\n> > >\n> > > > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\n> > > > \"AV worker\",\n> > > > ALLOCSET_DEFAULT_SIZES);\n> > >\n> > > I'm not sure the former needs to be fixed, but the latter is actually\n> > > visible to users via pg_log_backend_memory_contexts().\n> > >\n> > > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\n> >\n> > Good catch. I've seen the use of \"AV\" in some of the mem context\n> > names, why that? Let's be specific and say \"Autovacuum\". Attached\n> > patch does that. Please review it.\n>\n> +1. The patch looks good to me too.\n\nThanks all for reviewing this. Here's the CF entry -\nhttps://commitfest.postgresql.org/35/3378/\n\nRegards,\nBharath Rupireddy.\n\n\n","msg_date":"Thu, 28 Oct 2021 18:11:59 +0530","msg_from":"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>","msg_from_op":true,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"},{"msg_contents":"On 10/28/21, 5:42 AM, \"Bharath Rupireddy\" <bharath.rupireddyforpostgres@gmail.com> wrote:\r\n> Thanks all for reviewing this. Here's the CF entry -\r\n> https://commitfest.postgresql.org/35/3378/\r\n\r\nI've marked this one as ready-for-committer.\r\n\r\nNathan\r\n\r\n","msg_date":"Wed, 10 Nov 2021 19:45:23 +0000","msg_from":"\"Bossart, Nathan\" <bossartn@amazon.com>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too\n long to start; canceled\" specific to \"auto"},{"msg_contents":"On 2021-Oct-28, Bharath Rupireddy wrote:\n\n> Thanks all for reviewing this. Here's the CF entry -\n> https://commitfest.postgresql.org/35/3378/\n\nThanks, pushed. I changed a couple of things though -- notably changed\nthe elog() to ereport() as suggested by Nathan early on, but never\nmaterialized in the submitted patch. I also changed the wording of the\ncontext names, since the proposed ones weren't much more satisfactory\nthan the existing ones.\n\n-- \nÁlvaro Herrera 39°49'30\"S 73°17'W — https://www.EnterpriseDB.com/\n\"Every machine is a smoke machine if you operate it wrong enough.\"\nhttps://twitter.com/libseybieda/status/1541673325781196801\n\n\n","msg_date":"Mon, 22 Nov 2021 13:25:45 -0300","msg_from":"Alvaro Herrera <alvherre@alvh.no-ip.org>","msg_from_op":false,"msg_subject":"Re: Isn't it better with \"autovacuum worker....\" instead of \"worker\n took too long to start; canceled\" specific to \"auto"}],"string":"[\n {\n \"msg_contents\": \"Hi,\\n\\nIs there a specific reason that we have a generic WARNING \\\"worker took\\ntoo long to start; canceled\\\" for an autovacuum worker? Isn't it better\\nwith \\\"autovacuum worker took too long to start; canceled\\\"? It is\\nconfusing to see the generic message in the server logs while\\ndebugging an issue for a user who doesn't know the internals of\\nautovacuum code.\\n\\nTo be more informative about the message, how about the following:\\n1) ereport(WARNING,\\n (errmsg( \\\"worker took too long to start\\\"),\\n errdetail(\\\"Previous attempt to start autovacuum\\nworker was failed, canceled.\\\")));\\nor\\n2) ereport(WARNING,\\n (errmsg( \\\"worker took too long to start, canceled\\\"),\\n errdetail(\\\"The postmaster couldn't start an\\nautovacuum worker.\\\")));\\nor\\n3) ereport(WARNING,\\n (errmsg( \\\"worker took too long to start, canceled\\\"),\\n errdetail(\\\"Previous attempt to start autovacuum\\nworker was failed.\\\")));\\nor\\n4) elog(WARNING, \\\"postmaster couldn't start an autovacuum worker\\\");\\n\\nThoughts?\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 21:56:37 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker took\\n too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On 10/27/21, 9:29 AM, \\\"Bharath Rupireddy\\\" <bharath.rupireddyforpostgres@gmail.com> wrote:\\r\\n> Is there a specific reason that we have a generic WARNING \\\"worker took\\r\\n> too long to start; canceled\\\" for an autovacuum worker? Isn't it better\\r\\n> with \\\"autovacuum worker took too long to start; canceled\\\"? It is\\r\\n> confusing to see the generic message in the server logs while\\r\\n> debugging an issue for a user who doesn't know the internals of\\r\\n> autovacuum code.\\r\\n\\r\\nIt looks like it has been this way for a while [0]. I don't know if\\r\\nI've ever seen this message before, and from the comments near it, it\\r\\nsounds like it is expected to rarely happen.\\r\\n\\r\\n> To be more informative about the message, how about the following:\\r\\n\\r\\nMy vote is to just change it to\\r\\n\\r\\n ereport(WARNING,\\r\\n (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\r\\n\\r\\nand call it a day. If we wanted to add errdetail(), I think we should\\r\\nmake sure it is providing useful context, but I'm not sure what that\\r\\nmight look like.\\r\\n\\r\\nNathan\\r\\n\\r\\n[0] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=bae0b56\\r\\n\\r\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 19:05:10 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too\\n long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\\n> On 10/27/21, 9:29 AM, \\\"Bharath Rupireddy\\\" <bharath.rupireddyforpostgres@gmail.com> wrote:\\n> > Is there a specific reason that we have a generic WARNING \\\"worker took\\n> > too long to start; canceled\\\" for an autovacuum worker? Isn't it better\\n> > with \\\"autovacuum worker took too long to start; canceled\\\"? It is\\n> > confusing to see the generic message in the server logs while\\n> > debugging an issue for a user who doesn't know the internals of\\n> > autovacuum code.\\n> \\n> It looks like it has been this way for a while [0]. I don't know if\\n> I've ever seen this message before, and from the comments near it, it\\n> sounds like it is expected to rarely happen.\\n\\nI was surprised to see that I have only two logs for this in the last 8 weeks.\\n\\n> > To be more informative about the message, how about the following:\\n> \\n> My vote is to just change it to\\n> \\n> ereport(WARNING,\\n> (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\n> \\n> and call it a day. If we wanted to add errdetail(), I think we should\\n> make sure it is providing useful context, but I'm not sure what that\\n> might look like.\\n\\nI think that's fine.\\n\\nNote that the backend_type is illuminating for those who use CSV logs, or use\\nP13+ and log_line_prefix += %b (see 70a7b4776).\\n\\nsession_line | 1\\nerror_severity | WARNING\\nmessage | worker took too long to start; canceled\\nbackend_type | autovacuum launcher\\n\\n-- \\nJustin\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Oct 2021 14:26:11 -0500\",\n \"msg_from\": \"Justin Pryzby <pryzby@telsasoft.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in \\n> On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\\n> > My vote is to just change it to\\n> > \\n> > ereport(WARNING,\\n> > (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\n> > \\n> > and call it a day. If we wanted to add errdetail(), I think we should\\n> > make sure it is providing useful context, but I'm not sure what that\\n> > might look like.\\n> \\n> I think that's fine.\\n\\n+1\\n\\n> Note that the backend_type is illuminating for those who use CSV logs, or use\\n> P13+ and log_line_prefix += %b (see 70a7b4776).\\n> \\n> session_line | 1\\n> error_severity | WARNING\\n> message | worker took too long to start; canceled\\n> backend_type | autovacuum launcher\\n\\nYeah, the additional \\\"autovacuum\\\" is not noisy at all even in that\\ncontext. Some other messages are prefixed with \\\"autovacuum\\\".\\n\\n \\\"could not fork autovacuum worker process: %m\\\"\\n \\\"autovacuum worker started without a worker entry\\\"\\n\\nBy a quick look all occurances of \\\"laucher\\\" are prefixed with\\n\\\"autovacuum\\\" or \\\"logical replcaion\\\", which seems fine.\\n\\nAs a related topic, autovacuum.c has another use of bare \\\"worker\\\"s.\\n\\n>\\ttmpcxt = AllocSetContextCreate(CurrentMemoryContext,\\n>\\t\\t\\t\\t\\t\\t\\t\\t \\\"Start worker tmp cxt\\\",\\n>\\t\\t\\t\\t\\t\\t\\t\\t ALLOCSET_DEFAULT_SIZES);\\n\\n>\\tAutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\\n>\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t \\\"AV worker\\\",\\n>\\t\\t\\t\\t\\t\\t\\t\\t\\t\\t ALLOCSET_DEFAULT_SIZES);\\n\\nI'm not sure the former needs to be fixed, but the latter is actually\\nvisible to users via pg_log_backend_memory_contexts().\\n\\nLOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\\n\\nregards.\\n\\n-- \\nKyotaro Horiguchi\\nNTT Open Source Software Center\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 10:41:43 +0900 (JST)\",\n \"msg_from\": \"Kyotaro Horiguchi <horikyota.ntt@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of\\n \\\"worker took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\\n<horikyota.ntt@gmail.com> wrote:\\n>\\n> At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\\n> > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\\n> > > My vote is to just change it to\\n> > >\\n> > > ereport(WARNING,\\n> > > (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\n> > >\\n> > > and call it a day. If we wanted to add errdetail(), I think we should\\n> > > make sure it is providing useful context, but I'm not sure what that\\n> > > might look like.\\n> >\\n> > I think that's fine.\\n>\\n> +1\\n\\nDone.\\n\\n> > Note that the backend_type is illuminating for those who use CSV logs, or use\\n> > P13+ and log_line_prefix += %b (see 70a7b4776).\\n> >\\n> > session_line | 1\\n> > error_severity | WARNING\\n> > message | worker took too long to start; canceled\\n> > backend_type | autovacuum launcher\\n>\\n> Yeah, the additional \\\"autovacuum\\\" is not noisy at all even in that\\n> context. Some other messages are prefixed with \\\"autovacuum\\\".\\n>\\n> \\\"could not fork autovacuum worker process: %m\\\"\\n> \\\"autovacuum worker started without a worker entry\\\"\\n>\\n> By a quick look all occurances of \\\"laucher\\\" are prefixed with\\n> \\\"autovacuum\\\" or \\\"logical replcaion\\\", which seems fine.\\n>\\n> As a related topic, autovacuum.c has another use of bare \\\"worker\\\"s.\\n>\\n> > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\\n> > \\\"Start worker tmp cxt\\\",\\n> > ALLOCSET_DEFAULT_SIZES);\\n>\\n> > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\\n> > \\\"AV worker\\\",\\n> > ALLOCSET_DEFAULT_SIZES);\\n>\\n> I'm not sure the former needs to be fixed, but the latter is actually\\n> visible to users via pg_log_backend_memory_contexts().\\n>\\n> LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\\n\\nGood catch. I've seen the use of \\\"AV\\\" in some of the mem context\\nnames, why that? Let's be specific and say \\\"Autovacuum\\\". Attached\\npatch does that. Please review it.\\n\\nRegards,\\nBharath Rupireddy.\",\n \"msg_date\": \"Thu, 28 Oct 2021 08:13:58 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 28, 2021 at 8:14 AM Bharath Rupireddy\\n<bharath.rupireddyforpostgres@gmail.com> wrote:\\n>\\n> > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\\n>\\n> Good catch. I've seen the use of \\\"AV\\\" in some of the mem context\\n> names, why that? Let's be specific and say \\\"Autovacuum\\\". Attached\\n> patch does that. Please review it.\\n\\n+1, the error message and other improvements look good.\\n\\n-- \\nRegards,\\nDilip Kumar\\nEnterpriseDB: http://www.enterprisedb.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 09:52:19 +0530\",\n \"msg_from\": \"Dilip Kumar <dilipbalaut@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 28, 2021 at 11:44 AM Bharath Rupireddy\\n<bharath.rupireddyforpostgres@gmail.com> wrote:\\n>\\n> On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\\n> <horikyota.ntt@gmail.com> wrote:\\n> >\\n> > At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\\n> > > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\\n> > > > My vote is to just change it to\\n> > > >\\n> > > > ereport(WARNING,\\n> > > > (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\n> > > >\\n> > > > and call it a day. If we wanted to add errdetail(), I think we should\\n> > > > make sure it is providing useful context, but I'm not sure what that\\n> > > > might look like.\\n> > >\\n> > > I think that's fine.\\n> >\\n> > +1\\n>\\n> Done.\\n>\\n> > > Note that the backend_type is illuminating for those who use CSV logs, or use\\n> > > P13+ and log_line_prefix += %b (see 70a7b4776).\\n> > >\\n> > > session_line | 1\\n> > > error_severity | WARNING\\n> > > message | worker took too long to start; canceled\\n> > > backend_type | autovacuum launcher\\n> >\\n> > Yeah, the additional \\\"autovacuum\\\" is not noisy at all even in that\\n> > context. Some other messages are prefixed with \\\"autovacuum\\\".\\n> >\\n> > \\\"could not fork autovacuum worker process: %m\\\"\\n> > \\\"autovacuum worker started without a worker entry\\\"\\n> >\\n> > By a quick look all occurances of \\\"laucher\\\" are prefixed with\\n> > \\\"autovacuum\\\" or \\\"logical replcaion\\\", which seems fine.\\n> >\\n> > As a related topic, autovacuum.c has another use of bare \\\"worker\\\"s.\\n> >\\n> > > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\\n> > > \\\"Start worker tmp cxt\\\",\\n> > > ALLOCSET_DEFAULT_SIZES);\\n> >\\n> > > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\\n> > > \\\"AV worker\\\",\\n> > > ALLOCSET_DEFAULT_SIZES);\\n> >\\n> > I'm not sure the former needs to be fixed, but the latter is actually\\n> > visible to users via pg_log_backend_memory_contexts().\\n> >\\n> > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\\n>\\n> Good catch. I've seen the use of \\\"AV\\\" in some of the mem context\\n> names, why that? Let's be specific and say \\\"Autovacuum\\\". Attached\\n> patch does that. Please review it.\\n\\n+1. The patch looks good to me too.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nEDB: https://www.enterprisedb.com/\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 16:11:16 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On Thu, Oct 28, 2021 at 12:41 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Oct 28, 2021 at 11:44 AM Bharath Rupireddy\\n> <bharath.rupireddyforpostgres@gmail.com> wrote:\\n> >\\n> > On Thu, Oct 28, 2021 at 7:11 AM Kyotaro Horiguchi\\n> > <horikyota.ntt@gmail.com> wrote:\\n> > >\\n> > > At Wed, 27 Oct 2021 14:26:11 -0500, Justin Pryzby <pryzby@telsasoft.com> wrote in\\n> > > > On Wed, Oct 27, 2021 at 07:05:10PM +0000, Bossart, Nathan wrote:\\n> > > > > My vote is to just change it to\\n> > > > >\\n> > > > > ereport(WARNING,\\n> > > > > (errmsg(\\\"autovacuum worker took too long to start; canceled\\\")));\\n> > > > >\\n> > > > > and call it a day. If we wanted to add errdetail(), I think we should\\n> > > > > make sure it is providing useful context, but I'm not sure what that\\n> > > > > might look like.\\n> > > >\\n> > > > I think that's fine.\\n> > >\\n> > > +1\\n> >\\n> > Done.\\n> >\\n> > > > Note that the backend_type is illuminating for those who use CSV logs, or use\\n> > > > P13+ and log_line_prefix += %b (see 70a7b4776).\\n> > > >\\n> > > > session_line | 1\\n> > > > error_severity | WARNING\\n> > > > message | worker took too long to start; canceled\\n> > > > backend_type | autovacuum launcher\\n> > >\\n> > > Yeah, the additional \\\"autovacuum\\\" is not noisy at all even in that\\n> > > context. Some other messages are prefixed with \\\"autovacuum\\\".\\n> > >\\n> > > \\\"could not fork autovacuum worker process: %m\\\"\\n> > > \\\"autovacuum worker started without a worker entry\\\"\\n> > >\\n> > > By a quick look all occurances of \\\"laucher\\\" are prefixed with\\n> > > \\\"autovacuum\\\" or \\\"logical replcaion\\\", which seems fine.\\n> > >\\n> > > As a related topic, autovacuum.c has another use of bare \\\"worker\\\"s.\\n> > >\\n> > > > tmpcxt = AllocSetContextCreate(CurrentMemoryContext,\\n> > > > \\\"Start worker tmp cxt\\\",\\n> > > > ALLOCSET_DEFAULT_SIZES);\\n> > >\\n> > > > AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,\\n> > > > \\\"AV worker\\\",\\n> > > > ALLOCSET_DEFAULT_SIZES);\\n> > >\\n> > > I'm not sure the former needs to be fixed, but the latter is actually\\n> > > visible to users via pg_log_backend_memory_contexts().\\n> > >\\n> > > LOG: level: 1; AV worker: 8192 total in 1 blocks; 7928 free (0 chunks); 264 used\\n> >\\n> > Good catch. I've seen the use of \\\"AV\\\" in some of the mem context\\n> > names, why that? Let's be specific and say \\\"Autovacuum\\\". Attached\\n> > patch does that. Please review it.\\n>\\n> +1. The patch looks good to me too.\\n\\nThanks all for reviewing this. Here's the CF entry -\\nhttps://commitfest.postgresql.org/35/3378/\\n\\nRegards,\\nBharath Rupireddy.\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Oct 2021 18:11:59 +0530\",\n \"msg_from\": \"Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On 10/28/21, 5:42 AM, \\\"Bharath Rupireddy\\\" <bharath.rupireddyforpostgres@gmail.com> wrote:\\r\\n> Thanks all for reviewing this. Here's the CF entry -\\r\\n> https://commitfest.postgresql.org/35/3378/\\r\\n\\r\\nI've marked this one as ready-for-committer.\\r\\n\\r\\nNathan\\r\\n\\r\\n\",\n \"msg_date\": \"Wed, 10 Nov 2021 19:45:23 +0000\",\n \"msg_from\": \"\\\"Bossart, Nathan\\\" <bossartn@amazon.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too\\n long to start; canceled\\\" specific to \\\"auto\"\n },\n {\n \"msg_contents\": \"On 2021-Oct-28, Bharath Rupireddy wrote:\\n\\n> Thanks all for reviewing this. Here's the CF entry -\\n> https://commitfest.postgresql.org/35/3378/\\n\\nThanks, pushed. I changed a couple of things though -- notably changed\\nthe elog() to ereport() as suggested by Nathan early on, but never\\nmaterialized in the submitted patch. I also changed the wording of the\\ncontext names, since the proposed ones weren't much more satisfactory\\nthan the existing ones.\\n\\n-- \\nÁlvaro Herrera 39°49'30\\\"S 73°17'W — https://www.EnterpriseDB.com/\\n\\\"Every machine is a smoke machine if you operate it wrong enough.\\\"\\nhttps://twitter.com/libseybieda/status/1541673325781196801\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Nov 2021 13:25:45 -0300\",\n \"msg_from\": \"Alvaro Herrera <alvherre@alvh.no-ip.org>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Isn't it better with \\\"autovacuum worker....\\\" instead of \\\"worker\\n took too long to start; canceled\\\" specific to \\\"auto\"\n }\n]","isConversational":false}}}],"truncated":false,"partial":false},"paginationData":{"pageIndex":529,"numItemsPerPage":100,"numTotalItems":58371,"offset":52900,"length":100}},"jwt":"eyJhbGciOiJFZERTQSJ9.eyJyZWFkIjp0cnVlLCJwZXJtaXNzaW9ucyI6eyJyZXBvLmNvbnRlbnQucmVhZCI6dHJ1ZX0sImlhdCI6MTc4MDczNTcyMywic3ViIjoiL2RhdGFzZXRzL3dhbnNoZW5sL3Bnc3FsLWhhY2tlcnMiLCJleHAiOjE3ODA3MzkzMjMsImlzcyI6Imh0dHBzOi8vaHVnZ2luZ2ZhY2UuY28ifQ.0SX0Cuid3RtxERXnF4SBgjZoQK_OWTGG5v6ab7Byr-Rwk6Qdal_lY8ObRoAcTYsa7zraamyHETy6mZvdJLtnBA","displayUrls":true,"splitSizeSummaries":[{"config":"default","split":"train","numRows":58371,"numBytesParquet":368254123}]},"discussionsStats":{"closed":0,"open":0,"total":0},"fullWidth":true,"hasGatedAccess":true,"hasFullAccess":true,"isEmbedded":false,"savedQueries":{"community":[],"user":[]}}">
threads listlengths 1 2.99k |
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[
{
"msg_contents": "While working on something else, I noticed $SUBJECT, which I should\nhave updated in commit 27e1f1456. :-( There are two places that need\nto be updated, but in the first place the second one seemed a bit\nredundant to me, because it says the same thing as the first one, and\nis placed pret... |
[
{
"msg_contents": "Hello and thank you very much for the best open source database engine!\n\nThere's just this tiny but seemingly obvious issue that I can't believe I \nhaven't noticed until now: to_date(now(), 'TMmonth') returns 'october' in an \nEnglish locale (en_US.UTF-8 at least). Names of months and week... |
[
{
"msg_contents": "Hi All,\nsentPtr reported by WAL sender should usually never jump back, it\nshould always increase.\nI observed a strange behaviour with the WAL sender where sentPtr jumps\nback at the beginning. From code examination it looks like the\nfollowing behaviour is culprit.\n\nThe WAL sender reads ... |
[
{
"msg_contents": "Dear Hackers,\n\nWhile reading source codes about timeouts and GUC and I found that\nstrange behavior about client_connection_check_interval.\n\nCurrently we did not an assign_hook about client_connection_check_interval,\nthat means a timeout will not turn on immediately if users change the G... |
[
{
"msg_contents": "When producing a forked version of PostgreSQL, there is no \nstraightforward way to enforce that users don't accidentally load \nmodules built for the non-forked (standard, community) version. You can \nonly distinguish by PostgreSQL major version and a few compile-time \nsettings. (see int... |
[
{
"msg_contents": "Hi,\n\nI was able to create a table in \"information_schema\" schema, but\npg_dump does not dumps the table that was created in\n\"information_schema\" schema:\ncreate table information_schema.t1(c1 int);\n\nThe similar problem exists in case of create publication, we are able\nto create publ... |
[
{
"msg_contents": "Hi,\n\nIn a typical production environment, the user (not necessarily a\nsuperuser) sometimes wants to analyze the memory usage via\npg_backend_memory_contexts view or pg_log_backend_memory_contexts\nfunction which are accessible to only superusers. Isn't it better to\nallow non-superusers wi... |
[
{
"msg_contents": "Adjust configure to insist on Perl version >= 5.8.3.\n\nPreviously it only checked for version >= 5.8.0, although the\ndocumentation has said that the minimum version is 5.8.3 since\ncommit dea6ba939. Per the discussion leading up to that commit,\nI (tgl) left it that way intentionally becau... |
[
{
"msg_contents": "Hi,\n\nI noticed that for NetBSD we only have one animal, and it's running\nEOL'd release 7. To give decent visibility of relevant portability\nproblems it'd be nice to have one of the current supported releases[1]\nin there. CC'ing owner; any interest in updating this animal to 9.x?\n\nFor... |
[
{
"msg_contents": "We generally only expect amvacuumcleanup() routines to be called\nduring VACUUM. But some ginvacuumcleanup() calls are an exception to\nthat general rule -- these are calls made during autoanalyze, where\nginvacuumcleanup() does real pending list cleanup work (not just a\nno-op return). That'... |
[
{
"msg_contents": "Hi\n\nWhen 'ALTER FOREIGN DATA WRAPPER OPTIONS' is executed against \npostgres_fdw, the HINT message is printed as shown below, even though \nthere are no valid options in this context.\n\n=# ALTER FOREIGN DATA WRAPPER postgres_fdw OPTIONS (format 'csv');\nERROR: invalid option \"format\"\nHI... |
[
{
"msg_contents": "Hi hackers,\n\n== Background ==\n\nThis is a follow-up thread to `Add ZSON extension to /contrib/` [1].\nThe ZSON extension introduces a new type called ZSON, which is 100%\ncompatible with JSONB but uses a shared dictionary of strings most\nfrequently used by given JSONB documents for compre... |
[
{
"msg_contents": "Hi,\n\nThe commit [1] for the feature \"Remove temporary files after backend\ncrash\" introduced following in the docs:\n+ <para>\n+ When set to <literal>on</literal>, which is the default,\n+ <productname>PostgreSQL</productname> will automatically remove\n+ tempor... |
[
{
"msg_contents": "Hi,\n\nAt times, users want to know what are the files (snapshot and mapping\nfiles) that are available under pg_logical directory and also the\nspill files that are under pg_replslot directory and how much space\nthey occupy. This will help to better know the storage usage pattern\nof these ... |
[
{
"msg_contents": "Hi, hackers\n\n\nI notice that postgres use constraints to optimize/rewrite queries in\nlimited cases as\nhttps://www.postgresql.org/docs/current/runtime-config-query.html#GUC-CONSTRAINT-EXCLUSION\n.\n\n\nI propose two new types of query rewrites using constraints here\n\n1) Remove DISTINCT\n... |
[
{
"msg_contents": "Hi,\n\nwe have a replica product that access to wal files with logical replication.\n\nAfter a reboot following a database fault we receive the following issue.\n\n2021-10-08 16:07:31.829 CEST:127.0.0.1(49880):cdcadm@REPLICA:[12976]:\nERROR: unexpected duplicate for tablespace 16389, relfilen... |
[
{
"msg_contents": "Greetings hackers,\n\nI'm seeing some odd behavior around string prefix searching -\nhopefully I've missed something here (thanks to Nino Floris for\noriginally flagging this).\n\nIn PostgreSQL 11, a starts_with function and a ^@ operators were added\nfor string prefix checking, as an alterna... |
[
{
"msg_contents": "Hi,\n\nIt looks like auxiliary processes will not have a valid MyBackendId as\nthey don't call InitPostgres() and SharedInvalBackendInit() unlike\nbackends. But the startup process (which is an auxiliary process) in\nhot standby mode seems to be different in the way that it does have a\nvalid... |
[
{
"msg_contents": "Hi,\n\nCurrently pg_log_backend_memory_contexts() doesn't log the memory\ncontexts of auxiliary processes such as bgwriter, checkpointer, wal\nwriter, archiver, startup process and wal receiver. It will be useful\nto look at the memory contexts of these processes too, for debugging\npurposes ... |
[
{
"msg_contents": "When starts_with() and the equivalent ^@ operator were added, they\nwere plugged into the planner in only a rather half-baked way.\nSelectivity estimation got taught about the operator, but the\nother infrastructure associated with LIKE/regex matching wasn't\nupdated. This causes these opera... |
[
{
"msg_contents": "Hi all,\n\nIn building off of prior art regarding the 'pg_read_all_data' and\n'pg_write_all_data' roles, I would like to propose an extension to roles\nthat would allow for database-specific role memberships (for the purpose of\ngranting database-specific privileges) as an additional layer of... |
[
{
"msg_contents": "Hi,\n\nThe freebsd image I use for CI runs just failed because the package name for\nopenldap changed (it's now either openldap{24,25}-{client,server}, instead of\nopenldap-..}. I naively resolved that conflict by choosing the openldap25-*\npackages. Which unfortunately turns out to break 001... |
[
{
"msg_contents": "Hi\n\nI would like to fix an issue https://github.com/okbob/pspg/issues/188 where\nthe write to clipboard from pspg doesn`t work on macos. But it is hard to\nfix it without any macos. I am not a user of macos and I would not buy it\njust for this purpose.\n\nIs it possible to get some remote... |
[
{
"msg_contents": "While creating an \"export snapshot\" I don't see any protection why the\nnumber of xids in the snapshot can not cross the\n\"GetMaxSnapshotXidCount()\"?.\n\nBasically, while converting the HISTORIC snapshot to the MVCC snapshot\nin \"SnapBuildInitialSnapshot()\", we add all the xids between\... |
[
{
"msg_contents": "Hi,\n\nWhen testing logical replication, I found a case which caused assert coredump on\nlatest HEAD. The reproduction steps are as follows:\n\n1)\n----publisher----\ncreate table test(i int);\ncreate publication pub for table test;\nbegin;\n\ninsert into test values(1);\n\n2)\n----subscriber... |
[
{
"msg_contents": "Hi,\n\nThe comments for pgfdw_get_cleanup_result() say this:\n\n * It's not a huge problem if we throw an ERROR here, but if we get into error\n * recursion trouble, we'll end up slamming the connection shut, which will\n * necessitate failing the entire toplevel transaction even if subtransa... |
[
{
"msg_contents": "Hi All,\n\nWhile using IMMUTABLE functions in index expression, we are getting below\ncorruption on HEAD.\n\npostgres=# CREATE TABLE tab1 (c1 numeric, c2 numeric);\nCREATE TABLE\n\npostgres=# INSERT INTO tab1 values (10, 100);\nINSERT 0 1\n\npostgres=# CREATE OR REPLACE FUNCTION func1(var1 ... |
[
{
"msg_contents": "As reported at [1], if the transaction is aborted during export\nsnapshot then ExportInProgress and SavedResourceOwnerDuringExport are\nnot getting reset and that is throwing an error\n\"clearing exported snapshot in wrong transaction state\" while\nexecuting the next command. The attached p... |
[
{
"msg_contents": "The following bug has been logged on the website:\n\nBug reference: 17220\nLogged by: Matthijs van der Vleuten\nEmail address: postgresql@zr40.nl\nPostgreSQL version: 14.0\nOperating system: Debian sid\nDescription: \n\nUser 'musttu' on IRC reported the following b... |
[
{
"msg_contents": "Hi,\n\nWhile working on [1], it is found that currently the ProcState array\ndoesn't have entries for auxiliary processes, it does have entries for\nMaxBackends. But the startup process is eating up one slot from\nMaxBackends. We need to increase the size of the ProcState array by 1\nat least... |
[
{
"msg_contents": "This commit broke psql \\d datname.nspname.relname\n\ncommit 2c8726c4b0a496608919d1f78a5abc8c9b6e0868\nAuthor: Robert Haas <rhaas@postgresql.org>\nDate: Wed Feb 3 13:19:41 2021 -0500\n\n Factor pattern-construction logic out of processSQLNamePattern.\n...\n patternToSQLRegex is a litt... |
[
{
"msg_contents": "Hi,\n\n> The previous patch was failing because of the recent test changes made\n> by commit 201a76183e2 which unified new and get_new_node, attached\n> patch has the changes to handle the changes accordingly.\n> Thanks for your update!\n> I have two comments.\n\n1.Do we need “set_backtrace(N... |
[
{
"msg_contents": "Hi,\n\nQueryID is good tool for query analysis. I want to improve core jumbling \nmachinery in two ways:\n1. QueryID value should survive dump/restore of a database (use fully \nqualified name of table instead of relid).\n2. QueryID could represent more general class of queries: for example, ... |
[
{
"msg_contents": "Hi,\n\nFor the last year or so I've on and off tinkered with $subject. I think\nit's in a state worth sharing now. First, let's look at a little\ncomparison.\n\nMy workstation:\n\nnon-cached configure:\ncurrent: 11.80s\nmeson: 6.67s\n\nnon-cached build (world-bin):\ncurrent... |
[
{
"msg_contents": "Hi hackers,\n\nI noticed that `make install` updates modification time for all\ninstalled headers. This leads to recompilation of all dependent\nobjects, which is inconvenient for example when working on a\nthird-party extension. A way to solve this would be to pass\n`INSTALL=\"install -p\"` ... |
[
{
"msg_contents": "While working on the issue [1], I realize that if a subtransaction\nhasn't done any catalog change then we don't add this in the commit\nxid list even if we are building a full snapshot [2]. That means when\nwe will convert this to the MVCC snapshot we will add this to a\nrunning xid list. ... |
[
{
"msg_contents": "I am very new to this list, so I don’t know whether this is the right place.\n\nMicrosoft SQL and MySQL both use the @ sign at the beginning of their \nvariables. The most obvious benefit of this is that it is very easy to \ndistinguish between variable names and column names.\n\nI’m not aski... |
[
{
"msg_contents": "In a blog post (https://about.gitlab.com/blog/2021/09/29/why-we-spent-the-last-month-eliminating-postgresql-subtransactions/),\nI described how PostgreSQL can enter into a suboverflow condition on\nthe replica under a number of conditions:\n\n1. A long transaction starts.\n2. A single SAVEPOI... |
[
{
"msg_contents": "Hi,\n\nI see that the recoveryStopsAfter() doesn't have any \"recovery\nstopping after XXXX\" sort of log for RECOVERY_TARGET_TIME recovery\ntarget type. It has similar logs for other recoveryTarget types\nthough. Is there any specific reason for not having it?\n\nI see that we have \"startin... |
[
{
"msg_contents": "As you might have seen from my email in another thread, thanks to\nStephen and Cybertec staff, I am back working on cluster file\nencryption/TDE.\n\nStephen was going to research if XTS cipher mode would be a good fit for\nthis since it was determined that CTR cipher mode was too vulnerable t... |
[
{
"msg_contents": "Hi, all\nI have some doubts about the request xlog streaming startpoint in WaitForWALToBecomeAvailable(). In this function, RecPtr is the endpoint lsn we are waiting for, tliRecPtr is the position of the WAL record we are interested in, I want to know why use RecPtr rather than tliRecPtr as t... |
[
{
"msg_contents": "Hi All,\n\nPublisher 'DateStyle' is set as \"SQL, MDY\", whereas in Subscriber as\n\"SQL, DMY\", the logical replication is not working...\n\n From Publisher:\npostgres=# INSERT INTO calendar VALUES ('07-18-1036', '1'), ('05-15-1135', '1');\nINSERT 0 2\n\nGetting below error in the subscriber... |
[
{
"msg_contents": "Hi,\n\n\nHere is a proposal to implement HIDDEN columns feature in PostgreSQL.\n\nThe user defined columns are always visible in the PostgreSQL. If user\nwants to hide some column(s) from a SELECT * returned values then the\nhidden columns feature is useful. Hidden column can always be used a... |
[
{
"msg_contents": "According to getpwnam(3):\n\n An application that wants to determine its user's home directory\n should inspect the value of HOME (rather than the value\n getpwuid(getuid())->pw_dir) since this allows the user to modify\n their notion of \"the home directory\" during a login session.\n\nT... |
[
{
"msg_contents": "Hello!\n \nWhen extension pg_stat_statsement is loaded into memory or compute_query_id=on in postgesql.conf\nmany of installcheck tests give errors.\nThe thing is that in *.out files appear lines \"queryid = xxxxx\" where xxxxx - some numeric value.\nSo 24 of 209 installcheck tests will fail... |
[
{
"msg_contents": "Hi,\n\nIn another logical replication related thread[1], my colleague Greg found that\nif publish_via_partition_root is true, then the child table's data will be\ncopied twice when adding both child and parent table to the publication.\n\nExample:\n\n-----\nPub:\ncreate table tbl1 (a int) par... |
[
{
"msg_contents": "Hi.\n\nOne of the issues when we try to use sharding in PostgreSQL is absence \nof partial aggregates pushdown.\n\nI see several opportunities to alleviate this issue.\nIf we look at Citus, it implements aggregate, calculating internal state \nof an arbitrary agregate function and exporting i... |
[
{
"msg_contents": "In pgsql-docs, this patch has been recommended to you.\n\nLacking consensus and so not included is the the deletion of\ncomments pointing between the ref/MOVE and FETCH files. These\nwere of the form:\n\n <!-- Note the \"direction\" bit is also in ref/fetch.sgml -->\n\n\nThanks for the so... |
[
{
"msg_contents": "This removes the outer square brackets in the create_database.sgml\nfile's synopsis. In the command sysopses, this is the only case\nwhere an optional group contains only optional groups.\n\nRob",
"msg_date": "Fri, 15 Oct 2021 13:13:14 -0400",
"msg_from": "rir <rirans@comcast.net>",
... |
[
{
"msg_contents": "While fooling with something else, I happened to notice $SUBJECT.\nThe reason turns out to be that it's checking the wrong element\nof the tblinfo[] array; see one-liner fix attached.\n\nI had a feeling of deja vu about this bug, and indeed a dig in\nthe git history shows that we fixed it in ... |
[
{
"msg_contents": "Hi\n\nI played with one dynamic access to record's fields. I was surprised so I\ncannot to access to record field from dynamic SQL. Is there some reason why\nit is not possible? Today all composite types in PL/pgSQL are records:\n\ndo $$\ndeclare r record; _relname varchar;\nbegin\n for r in... |
[
{
"msg_contents": "Attached is a proposed patch that refactors getTables() along the\nsame lines as some previous work (eg 047329624, ed2c7f65b, daa9fe8a5)\nto avoid having multiple partially-redundant copies of the SQL query.\nThis gets rid of nearly 300 lines of duplicative spaghetti code,\ncreates a uniform ... |
[
{
"msg_contents": "From: Mikhail <mp39590@gmail.com>\n\nWe might be in situation when we have \"just enough\" semaphores in the\nsystem limit to start but previously crashed unexpectedly, in that case\nwe won't be able to start again - semget() will return ENOSPC, despite\nthe semaphores are ours, and we can re... |
[
{
"msg_contents": "While poking at pg_dump for some work I'll show later, I grew quite\nunhappy with the extent to which people have ignored this advice\ngiven near the head of getTables():\n\n * Note: in this phase we should collect only a minimal amount of\n * information about each table, basically j... |
[
{
"msg_contents": "Hi hackers,\n\nI'm writing an extension that employs `object_access_hook`. I want to\nmonitor the table creation event and record the mapping between `reloid`\nand `relfilenode` during a transaction. Here's my code snippet,\n\n```\nstatic void\nmy_object_access_hook(ObjectAccessType access,\n... |
[
{
"msg_contents": "Hi, all\nI noticed that the \"else\" is missing during the error report after FileWrite() of mdwrite()/mdextend(), short write error is supposed to be reported when written bytes is not less than 0.\nI modified it in the attached patch:\ndiff --git a/src/backend/storage/smgr/md.c b/src/backen... |
[
{
"msg_contents": "Hi!\n\nI am still hoping to finish my work on reloptions I've started some years ago.\n\nI've renewed my patch and I think I need help from core team to finish it.\n\nGeneral idea of the patch: Now we have three ways to define options for \ndifferent objects, with more or less different code ... |
[
{
"msg_contents": "Hi all,\n\n$subject has been noticed on github here:\nhttps://github.com/postgres/postgres/pull/70/commits\n\nLooking at the MSIs of OpenSSL for Win64 and Win32, there are no\nchanges in the deliverable names or paths, meaning that something as\nsimple as the attached patch is enough to make ... |
[
{
"msg_contents": "Hi hackers,\n\nI couldn’t find a similar report to this one, so starting a new thread. I can reproduce this on v14.0 as well as PostgreSQL 12.5 (not tried below versions).\n\nSteps to reproduce:\n\nCREATE TYPE two_ints as (if1 int, if2 int);\nCREATE DOMAIN domain AS two_ints CHECK ((VALUE).if... |
[
{
"msg_contents": "Hi,\n\nI can (almost) consistently reproduce $subject by executing the\nattached shell script, which I was using while constructing a test\ncase for another thread.\n\nThe backtrace on the assert failure is this:\n\n(gdb) bt\n#0 0x00007fce0b018387 in raise () from /lib64/libc.so.6\n#1 0x000... |
[
{
"msg_contents": "\nHi, hackers\n\nWhile reading the patch in [1], I found there is an unexpected behavior when\nupdate the domain array that is based on a composite.\n\nSteps to reproduce:\n\n1)\nCREATE TYPE two_ints as (if1 int, if2 int);\nCREATE DOMAIN domain AS two_ints CHECK ((VALUE).if1 > 0);\nCREATE TAB... |
[
{
"msg_contents": "Hi hackers,\r\n\r\nI run 'make check-world' a lot, and I typically use parallelism and\r\nredirect stdout to /dev/null as suggested in the docs [0]. This seems\r\nto eliminate all of the test chatter except for this one message:\r\n\r\n NOTICE: database \"regression\" does not exist,... |
[
{
"msg_contents": "Hi,\n\nThis is a followup to\nhttp://postgr.es/m/CA+TgmoZ5A26C6OxKApafyuy_sx0VG6VXdD_Q6aSEzsvrPHDwzw@mail.gmail.com.\nI'm suspicious of the following code in CreateReplicationSlot:\n\n /* setup state for WalSndSegmentOpen */\n sendTimeLineIsHistoric = false;\n sendTimeLine = ThisTime... |
[
{
"msg_contents": "\nThe problem I'm writing about (h/t Simon Riggs for finding it) is\nillustrated by the following snippet of java:\n\n public static void runtest(Connection conn) throws Exception {\n Statement stmt = conn.createStatement();\n stmt.setFetchSize(10);\n ResultSet rs = ... |
[
{
"msg_contents": "Greetings -hackers,\n\nEnclosed is a patch that implements CREATE ROLE IF NOT EXISTS (along with\nthe same support for USER/GROUP). This is a fairly straightforward\napproach in that we do no validation of anything other than existence, with\nthe user needing to ensure that permissions/grant... |
[
{
"msg_contents": "Hi,\n\nWhen I read the documents and source code of wait evens,\nI found that the following wait events are never reported.\n\n* LogicalChangesRead: Waiting for a read from a logical changes file.\n* LogicalChangesWrite: Waiting for a write to a logical changes file.\n* LogicalSubxactRead: Wa... |
[
{
"msg_contents": "Hi hackers,\n\nOne of our test runs under the memory sanitizer cathed [1] the\nfollowing stacktrace:\n\n```\nheaptuple.c:1044:13: runtime error: load of value 111, which is not a\nvalid value for type '_Bool'\n #0 0x55fbb5e0857b in heap_form_tuple\n/home/runner/pgbuild/src/backend/access/c... |
[
{
"msg_contents": "Hi all,\n\nI have been wondering about some things related to schema privileges:\n\n1) Why do visibility rules apply to the \\d command, but not to system\ntables? What is the purpose of hiding stuff from \\d output while users\ncan get the same info another way?\n\n2) What is the reasoning b... |
[
{
"msg_contents": "Hi,\n\nThe FATAL error \"recovery ended before configured recovery target was\nreached\" introduced by commit at [1] in PG 14 is causing the standby\nto go down after having spent a good amount of time in recovery. There\ncan be cases where the arrival of required WAL (for reaching recovery\... |
[
{
"msg_contents": "Hi,\n\nPerennially our users have complaints about slow count(*) when coming from\nsome other systems. Index-only scans help, but I think we can do better. I\nrecently wondered if a BRIN index could be used to answer min/max aggregate\nqueries over the whole table, and it turns out it doesn't... |
[
{
"msg_contents": "These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n\nThe purpose of these patches is to allow non-superusers to configure most aspects of a system, so long as they belong to the appropriate privileged role(s):\n... |
[
{
"msg_contents": "These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n\nThe purpose of these patches is to allow ordinary users to create and own event triggers without introducing escalation attack vectors:\n\n\n\n\n\n\n[1] https... |
[
{
"msg_contents": "These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n\nThe purpose of these patches is to fix the CREATEROLE escalation attack vector misfeature. (Not everyone will see CREATEROLE that way, but the perceived valu... |
[
{
"msg_contents": "These patches have been split off the now deprecated monolithic \"Delegating superuser tasks to new security roles\" thread at [1].\n\nThe purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables they lack privilege to write directly. This... |
[
{
"msg_contents": "Hi,\n\nI wonder if we really need signals to implement interrupts. Given\nthat they are non-preemptive/cooperative (work happens at the next\nCFI()), why not just use shared memory flags and latches? That skips\na bunch of code, global variables and scary warnings about programming\nin sign... |
[
{
"msg_contents": "Attached is a series of patches that address some performance and\ncorrectness problems we've recently identified in pg_dump.\n\nPatch 0001 refactors the way pg_dump keeps track of which \"components\"\n(definition, data, comment, ACL, etc) of a dumpable object need to be\ndumped. The proble... |
[
{
"msg_contents": "Remove unused wait events.\n\nCommit 464824323e introduced the wait events which were neither used by\nthat commit nor by follow-up commits for that work.\n\nAuthor: Masahiro Ikeda\nBackpatch-through: 14, where it was introduced\nDiscussion: https://postgr.es/m/ff077840-3ab2-04dd-bbe4-4f5dfd2... |
[
{
"msg_contents": "Hi,\n\nI'd like to propose to add new wait event reported while archiver process\nis executing archive_command. This would be helpful to observe\nwhat archiver is doing and check whether it has some troubles or not.\nThought? PoC patch attached.\n\nAlso how about adding wait events for other ... |
[
{
"msg_contents": "One problem I've seen in multiple databases and is when a table has a\nmixture of data sets within it. E.g. A queue table where 99% of the\nentries are \"done\" but most queries are working with the 1% that are\n\"new\" or in other states. Often the statistics are skewed by the\n\"done\" entr... |
[
{
"msg_contents": "Hi,\nw.r.t. 0001-Partial-aggregates-push-down-v03.patch\n\nFor partial_agg_ok(),\n\n+ if (agg->aggdistinct || agg->aggvariadic || agg->aggkind !=\nAGGKIND_NORMAL || agg->aggorder != NIL)\n+ ok = false;\n\nSince SearchSysCache1() is not called yet, you can return false directly.\n\n+ ... |
[
{
"msg_contents": "Today, pg_dump does a lot of internal lookups via binary search\nin presorted arrays. I thought it might improve matters\nto replace those binary searches with hash tables, theoretically\nconverting O(log N) searches into O(1) searches. So I tried making\na hash table indexed by CatalogId (... |
[
{
"msg_contents": "I returned to the 1995 paper \"Efficient Search of Multidimensional\nB-Trees\" [1] as part of the process of reviewing v39 of the skip scan\npatch, which was posted back in May. It's a great paper, and anybody\ninvolved in the skip scan effort should read it thoroughly (if they\nhaven't alrea... |
[
{
"msg_contents": "Hello there hackers,\n\nWe at Zalando have faced some issues around long running idle\ntransactions and were thinking about increasing the visibility of\npg_stat_* views to capture them easily. What I found is that currently\nin pg_stat_activity there is a lot of good information about the\nc... |
[
{
"msg_contents": "Hi hackers,\n\nDuring the discussion [1] it was discovered that we have two\nprocedures in execTuples.c that do the same thing:\n\n* MakeSingleTupleTableSlot()\n* MakeTupleTableSlot()\n\nIn fact, MakeSingleTupleTableSlot() is simply a wrapper for\nMakeTupleTableSlot().\n\nI propose keeping on... |
[
{
"msg_contents": "Hackers,\n\nI noticed recently that permissions checking is done differently for the \nserver certificate key than the client key. Specifically, on the server \nthe key can have 640 perms if it is owned by root.\n\nOn the server side this change was made in 9a83564c and I think the same \nrat... |
[
{
"msg_contents": "Hello Tom!\n\nI noticed you are improving pg_dump just now.\n\nSome time ago I experimented with a customer database dump in parallel directory mode -F directory -j (2-4)\n\nI noticed it took quite long to complete.\n\nFurther investigation showed that in this mode with multiple jobs the tabl... |
[
{
"msg_contents": "While doing some desultory testing, I realized that the commit\nI just pushed (92316a458) broke pg_dump against 8.0 servers:\n\n$ pg_dump -p5480 -s regression\npg_dump: error: schema with OID 11 does not exist\n\nThe reason turns out to be something I'd long forgotten about: except\nfor the f... |
[
{
"msg_contents": "Simple patch to implement $SUBJECT attached.\n\npg_signal_backend seems like the appropriate predefined role, because\npg_log_backend_memory_contexts() is implemented by a sending signal.\n\nRegards,\n\tJeff Davis",
"msg_date": "Sat, 23 Oct 2021 12:57:02 -0700",
"msg_from": "Jeff Davi... |
[
{
"msg_contents": "Add new predefined role pg_maintenance, which can issue VACUUM,\nANALYZE, CHECKPOINT.\n\nPatch attached.\n\nRegards,\n\tJeff Davis",
"msg_date": "Sat, 23 Oct 2021 14:45:02 -0700",
"msg_from": "Jeff Davis <pgsql@j-davis.com>",
"msg_from_op": true,
"msg_subject": "Predefined rol... |
[
{
"msg_contents": "Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.\n\nCIC and REINDEX CONCURRENTLY assume backends see their catalog changes\nno later than each backend's next transaction start. That failed to\nhold when a backend absorbed a relevant invalidation in the middle of\nrunnin... |
[
{
"msg_contents": "Hi everyone. I want to do some feature request regarding indexes, as far as\nI know this kind of functionality doesn't exists in Postgres. Here is my\nproblem :\nI need to create following indexes:\n Create index job_nlp_year_scan on ingest_scans_stageing\n(`job`,`nlp`,`year`,`scan_id`... |
[
{
"msg_contents": "Hello.\n\nI noticed that the following command doesn't leave connection log in\nlog file.\n\n> psql \"host=localhost options=-c\\ log_connections=on\"\n\nThe reason is we log connections before the options is processed. We\nneed to move the code from BackendInitialize to InitPostgres where\n... |
[
{
"msg_contents": "src/port/snprintf.c: Optimize the common base=10 case in fmtint\n\nfmtint() turns an integer into a string for a given base, and to do this\nit does a divide/modulo operation iteratively.\n\nOn just about any CPU, divides are a pretty expensive operation, generally\n10x to 20x or more expensi... |
[
{
"msg_contents": "Hi,\n\nour make dependencies currently are insufficient to trigger client binaries to\nbe relinked when pgport/pgcommon/libpq/... changes.\n\nTo reproduce, you can use something like:\ntouch ~/src/postgresql/src/port/snprintf.c && make -j48 2>&1|grep 'gcc.*pgbench'\nwhich won't show anything,... |
[
{
"msg_contents": "Hi,\r\n\r\nSince PostgreSQL 12 (0516c61b756e39) we have allowed for the ability to \r\nset \"clientcert=verify-full\" against various HBA authentication methods. \r\nThis provides the ability to provide \"multi-factor authentication\" e.g. \r\na client must provide both a valid certificate wi... |
[
{
"msg_contents": "[PATCH v2] src/port/snprintf.c: Optimize the common base=10 case in fmtint\n\nfmtint() turns an integer into a string for a given base, and to do this\nit does a divide/modulo operation iteratively.\nThe only possible base values are 8, 10 and 16\n\nOn just about any CPU, divides are a pretty... |
[
{
"msg_contents": "Generally if a role is granted membership to another role with NOINHERIT\nthey must use SET ROLE to access the privileges of that role, however\nwith predefined roles the membership and privilege is conflated, as\ndemonstrated by:\n\nCREATE ROLE readrole;\nCREATE ROLE role2 NOINHERIT;\nCREATE... |
[
{
"msg_contents": "Hi,\n\nA while back I'd reported [1] to the wine bugs list that their popen() doesn't\nquite work. Which I noticed because it made initdb.exe hang in wine.\n\nThat was just fixed. And I verified that with a bleeding edge wine the windows\ninitdb.exe actually succeeds (although I nuked the roo... |
[
{
"msg_contents": "I've been investigating the poor performance of a WITH RECURSIVE\nquery, which I've recreated with test data.\n\nThe first thing was to re-write the query, which helped improve\nperformance by about 30%, but the plan was still very bad. With a\nsmall patch I've been able to improve performanc... |
[
{
"msg_contents": "Hi,\n\nIs there a specific reason that we have a generic WARNING \"worker took\ntoo long to start; canceled\" for an autovacuum worker? Isn't it better\nwith \"autovacuum worker took too long to start; canceled\"? It is\nconfusing to see the generic message in the server logs while\ndebugging... |
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