\\n> I've evaluated the performance of node1 but the result seems to show\\n> the opposite.\\n\\nAs an aside, I meant the loop in our node3 might make your node1 slower\\nthan the prototype's node1, which was coded for 1 member only.\\n\\n> > > * Node shrinking support. Low priority.\\n> >\\n> > This is an architectural wart that's been neglected since the tid store\\ndoesn't perform deletion. We'll need it sometime. If we're not going to\\nmake this work, why ship a deletion API at all?\\n> >\\n> > I took a look at this a couple weeks ago, and fixing it wouldn't be\\nthat hard. I even had an idea of how to detect when to shrink size class\\nwithin a node kind, while keeping the header at 5 bytes. I'd be willing to\\nput effort into that, but to have a chance of succeeding, I'm unwilling to\\nmake it more difficult by adding more size classes at this point.\\n>\\n> I think that the deletion (and locking support) doesn't have use cases\\n> in the core (i.e. tidstore) but is implemented so that external\\n> extensions can use it.\\n\\nI think these cases are a bit different: Doing anything with a data\\nstructure stored in shared memory without a synchronization scheme is\\ncompletely unthinkable and insane. I'm not yet sure if\\ndeleting-without-shrinking is a showstopper, or if it's preferable in v16\\nthan no deletion at all.\\n\\nAnything we don't implement now is a limit on future use cases, and thus a\\ncause for objection. On the other hand, anything we implement also\\nrepresents more stuff that will have to be rewritten for high-concurrency.\\n\\n> FYI, I've run TPC-C workload over the weekend, and didn't get any\\n> failures of the assertion proving tidstore and the current tid lookup\\n> return the same result.\\n\\nGreat!\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Mar 13, 2023 at 8:41 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> On Sun, Mar 12, 2023 at 12:54 AM John Naylor> <john.naylor@enterprisedb.com> wrote:> >> > On Fri, Mar 10, 2023 at 9:30 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:> > > * Additional size classes. It's important for an alternative of path> > > compression as well as supporting our decoupling approach. Middle> > > priority.> >> > I'm going to push back a bit and claim this doesn't bring much gain, while it does have a complexity cost. The node1 from Andres's prototype is 32 bytes in size, same as our node3, so it's roughly equivalent as a way to ameliorate the lack of path compression.>> But does it mean that our node1 would help reduce the memory further> since since our base node type (i.e. RT_NODE) is smaller than the base> node type of Andres's prototype? The result I shared before showed> 1.2GB vs. 1.9GB.The benefit is found in a synthetic benchmark with random integers. I highly doubt that anyone would be willing to force us to keep binary-searching the 1GB array for one more cycle on account of not adding a size class here. I'll repeat myself and say that there are also maintenance costs.In contrast, I'm fairly certain that our attempts thus far at memory accounting/limiting are not quite up to par, and lacking enough to jeopardize the feature. We're already discussing that, so I'll say no more.> > I say \\\"roughly\\\" because the loop in node3 is probably noticeably slower. A new size class will by definition still use that loop.>> I've evaluated the performance of node1 but the result seems to show> the opposite.As an aside, I meant the loop in our node3 might make your node1 slower than the prototype's node1, which was coded for 1 member only. > > > * Node shrinking support. Low priority.> >> > This is an architectural wart that's been neglected since the tid store doesn't perform deletion. We'll need it sometime. If we're not going to make this work, why ship a deletion API at all?> >> > I took a look at this a couple weeks ago, and fixing it wouldn't be that hard. I even had an idea of how to detect when to shrink size class within a node kind, while keeping the header at 5 bytes. I'd be willing to put effort into that, but to have a chance of succeeding, I'm unwilling to make it more difficult by adding more size classes at this point.>> I think that the deletion (and locking support) doesn't have use cases> in the core (i.e. tidstore) but is implemented so that external> extensions can use it. I think these cases are a bit different: Doing anything with a data structure stored in shared memory without a synchronization scheme is completely unthinkable and insane. I'm not yet sure if deleting-without-shrinking is a showstopper, or if it's preferable in v16 than no deletion at all.Anything we don't implement now is a limit on future use cases, and thus a cause for objection. On the other hand, anything we implement also represents more stuff that will have to be rewritten for high-concurrency.> FYI, I've run TPC-C workload over the weekend, and didn't get any> failures of the assertion proving tidstore and the current tid lookup> return the same result.Great!--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 13 Mar 2023 20:28:09 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 13, 2023 at 10:28 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> On Mon, Mar 13, 2023 at 8:41 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Sun, Mar 12, 2023 at 12:54 AM John Naylor\\n> > <john.naylor@enterprisedb.com> wrote:\\n> > >\\n> > > On Fri, Mar 10, 2023 at 9:30 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > > * Additional size classes. It's important for an alternative of path\\n> > > > compression as well as supporting our decoupling approach. Middle\\n> > > > priority.\\n> > >\\n> > > I'm going to push back a bit and claim this doesn't bring much gain, while it does have a complexity cost. The node1 from Andres's prototype is 32 bytes in size, same as our node3, so it's roughly equivalent as a way to ameliorate the lack of path compression.\\n> >\\n> > But does it mean that our node1 would help reduce the memory further\\n> > since since our base node type (i.e. RT_NODE) is smaller than the base\\n> > node type of Andres's prototype? The result I shared before showed\\n> > 1.2GB vs. 1.9GB.\\n>\\n> The benefit is found in a synthetic benchmark with random integers. I highly doubt that anyone would be willing to force us to keep binary-searching the 1GB array for one more cycle on account of not adding a size class here. I'll repeat myself and say that there are also maintenance costs.\\n>\\n> In contrast, I'm fairly certain that our attempts thus far at memory accounting/limiting are not quite up to par, and lacking enough to jeopardize the feature. We're already discussing that, so I'll say no more.\\n\\nI agree that memory accounting/limiting stuff is the highest priority.\\nSo what kinds of size classes do you think we need? node3, 15, 32, 61\\nand 256?\\n\\n>\\n> > > I say \\\"roughly\\\" because the loop in node3 is probably noticeably slower. A new size class will by definition still use that loop.\\n> >\\n> > I've evaluated the performance of node1 but the result seems to show\\n> > the opposite.\\n>\\n> As an aside, I meant the loop in our node3 might make your node1 slower than the prototype's node1, which was coded for 1 member only.\\n\\nAgreed.\\n\\n>\\n> > > > * Node shrinking support. Low priority.\\n> > >\\n> > > This is an architectural wart that's been neglected since the tid store doesn't perform deletion. We'll need it sometime. If we're not going to make this work, why ship a deletion API at all?\\n> > >\\n> > > I took a look at this a couple weeks ago, and fixing it wouldn't be that hard. I even had an idea of how to detect when to shrink size class within a node kind, while keeping the header at 5 bytes. I'd be willing to put effort into that, but to have a chance of succeeding, I'm unwilling to make it more difficult by adding more size classes at this point.\\n> >\\n> > I think that the deletion (and locking support) doesn't have use cases\\n> > in the core (i.e. tidstore) but is implemented so that external\\n> > extensions can use it.\\n>\\n> I think these cases are a bit different: Doing anything with a data structure stored in shared memory without a synchronization scheme is completely unthinkable and insane.\\n\\nRight.\\n\\n> I'm not yet sure if deleting-without-shrinking is a showstopper, or if it's preferable in v16 than no deletion at all.\\n>\\n> Anything we don't implement now is a limit on future use cases, and thus a cause for objection. On the other hand, anything we implement also represents more stuff that will have to be rewritten for high-concurrency.\\n\\nOkay. Given that adding shrinking support also requires maintenance\\ncosts (and probably new test cases?) and there are no use cases in the\\ncore, I'm not sure it's worth supporting it at this stage. So I prefer\\neither shipping the deletion API as it is and removing the deletion\\nAPI. I think that it's a discussion point that we'd like to hear\\nfeedback from other hackers.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 13 Mar 2023 23:55:29 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n\\n> > > Since the block-level measurement is likely overestimating quite a\\nbit, I propose to simply reverse the order of the actions here, effectively\\nreporting progress for the *last page* and not the current one: First\\nupdate progress with the current memory usage, then add tids for this page.\\nIf this allocated a new block, only a small bit of that will be written to.\\nIf this block pushes it over the limit, we will detect that up at the top\\nof the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\",\\nbut simpler and less brittle. And, as far as OS pages we have actually\\nwritten to, I think it'll effectively respect the memory limit, at least in\\nthe local mem case. And the numbers will make sense.\\n> > >\\n> > > Thoughts?\\n> >\\n> > It looks to work but it still doesn't work in a case where a shared\\n> > tidstore is created with a 64kB memory limit, right?\\n> > TidStoreMemoryUsage() returns 1MB and TidStoreIsFull() returns true\\n> > from the beginning.\\n>\\n> I have two ideas:\\n>\\n> 1. Make it optional to track chunk memory space by a template parameter.\\nIt might be tiny compared to everything else that vacuum does. That would\\nallow other users to avoid that overhead.\\n> 2. When context block usage exceeds the limit (rare), make the additional\\neffort to get the precise usage -- I'm not sure such a top-down facility\\nexists, and I'm not feeling well enough today to study this further.\\n\\nSince then, Masahiko incorporated #1 into v31, and that's what I'm looking\\nat now. Unfortunately, If I had spent five minutes reminding myself what\\nthe original objections were to this approach, I could have saved us some\\neffort. Back in July (!), Andres raised two points: GetMemoryChunkSpace()\\nis slow [1], and fragmentation [2] (leading to underestimation).\\n\\nIn v31, in the local case at least, the underestimation is actually worse\\nthan tracking chunk space, since it ignores chunk header and alignment.\\nI'm not sure about the DSA case. This doesn't seem great.\\n\\nIt shouldn't be a surprise why a simple increment of raw allocation size is\\ncomparable in speed -- GetMemoryChunkSpace() calls the right function\\nthrough a pointer, which is slower. If we were willing to underestimate for\\nthe sake of speed, that takes away the reason for making memory tracking\\noptional.\\n\\nFurther, if the option is not specified, in v31 there is no way to get the\\nmemory use at all, which seems odd. Surely the caller should be able to ask\\nthe context/area, if it wants to.\\n\\nI still like my idea at the top of the page -- at least for vacuum and\\nm_w_m. It's still not completely clear if it's right but I've got nothing\\nbetter. It also ignores the work_mem issue, but I've given up anticipating\\nall future cases at the moment.\\n\\nI'll put this item and a couple other things together in a separate email\\ntomorrow.\\n\\n[1]\\nhttps://www.postgresql.org/message-id/20220704211822.kfxtzpcdmslzm2dy%40awork3.anarazel.de\\n[2]\\nhttps://www.postgresql.org/message-id/20220704220038.at2ane5xkymzzssb%40awork3.anarazel.de\\n\\n-- \\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nI wrote:> > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.> > >> > > Thoughts?> >> > It looks to work but it still doesn't work in a case where a shared> > tidstore is created with a 64kB memory limit, right?> > TidStoreMemoryUsage() returns 1MB and TidStoreIsFull() returns true> > from the beginning.>> I have two ideas:>> 1. Make it optional to track chunk memory space by a template parameter. It might be tiny compared to everything else that vacuum does. That would allow other users to avoid that overhead.> 2. When context block usage exceeds the limit (rare), make the additional effort to get the precise usage -- I'm not sure such a top-down facility exists, and I'm not feeling well enough today to study this further.Since then, Masahiko incorporated #1 into v31, and that's what I'm looking at now. Unfortunately, If I had spent five minutes reminding myself what the original objections were to this approach, I could have saved us some effort. Back in July (!), Andres raised two points: GetMemoryChunkSpace() is slow [1], and fragmentation [2] (leading to underestimation).In v31, in the local case at least, the underestimation is actually worse than tracking chunk space, since it ignores chunk header and alignment. I'm not sure about the DSA case. This doesn't seem great.It shouldn't be a surprise why a simple increment of raw allocation size is comparable in speed -- GetMemoryChunkSpace() calls the right function through a pointer, which is slower. If we were willing to underestimate for the sake of speed, that takes away the reason for making memory tracking optional.Further, if the option is not specified, in v31 there is no way to get the memory use at all, which seems odd. Surely the caller should be able to ask the context/area, if it wants to.I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.I'll put this item and a couple other things together in a separate email tomorrow.[1] https://www.postgresql.org/message-id/20220704211822.kfxtzpcdmslzm2dy%40awork3.anarazel.de[2] https://www.postgresql.org/message-id/20220704220038.at2ane5xkymzzssb%40awork3.anarazel.de-- John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 14 Mar 2023 18:27:37 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> I wrote:\\n>\\n> > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.\\n> > > >\\n> > > > Thoughts?\\n> > >\\n> > > It looks to work but it still doesn't work in a case where a shared\\n> > > tidstore is created with a 64kB memory limit, right?\\n> > > TidStoreMemoryUsage() returns 1MB and TidStoreIsFull() returns true\\n> > > from the beginning.\\n> >\\n> > I have two ideas:\\n> >\\n> > 1. Make it optional to track chunk memory space by a template parameter. It might be tiny compared to everything else that vacuum does. That would allow other users to avoid that overhead.\\n> > 2. When context block usage exceeds the limit (rare), make the additional effort to get the precise usage -- I'm not sure such a top-down facility exists, and I'm not feeling well enough today to study this further.\\n>\\n> Since then, Masahiko incorporated #1 into v31, and that's what I'm looking at now. Unfortunately, If I had spent five minutes reminding myself what the original objections were to this approach, I could have saved us some effort. Back in July (!), Andres raised two points: GetMemoryChunkSpace() is slow [1], and fragmentation [2] (leading to underestimation).\\n>\\n> In v31, in the local case at least, the underestimation is actually worse than tracking chunk space, since it ignores chunk header and alignment. I'm not sure about the DSA case. This doesn't seem great.\\n\\nRight.\\n\\n>\\n> It shouldn't be a surprise why a simple increment of raw allocation size is comparable in speed -- GetMemoryChunkSpace() calls the right function through a pointer, which is slower. If we were willing to underestimate for the sake of speed, that takes away the reason for making memory tracking optional.\\n>\\n> Further, if the option is not specified, in v31 there is no way to get the memory use at all, which seems odd. Surely the caller should be able to ask the context/area, if it wants to.\\n\\nThere are precedents that don't provide a way to return memory usage,\\nsuch as simplehash.h and dshash.c.\\n\\n>\\n> I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.\\n>\\n\\nWhat does it mean by \\\"the precise usage\\\" in your idea? Quoting from\\nthe email you referred to, Andres said:\\n\\n---\\nOne thing I was wondering about is trying to choose node types in\\nroughly-power-of-two struct sizes. It's pretty easy to end up with significant\\nfragmentation in the slabs right now when inserting as you go, because some of\\nthe smaller node types will be freed but not enough to actually free blocks of\\nmemory. If we instead have ~power-of-two sizes we could just use a single slab\\nof the max size, and carve out the smaller node types out of that largest\\nallocation.\\n\\nBtw, that fragmentation is another reason why I think it's better to track\\nmemory usage via memory contexts, rather than doing so based on\\nGetMemoryChunkSpace().\\n---\\n\\nIIUC he suggested measuring memory usage in block-level in order to\\ncount blocks that are not actually freed but some of its chunks are\\nfreed. That's why we used MemoryContextMemAllocated(). On the other\\nhand, recently you pointed out[1]:\\n\\n---\\nI think we're trying to solve the wrong problem here. I need to study\\nthis more, but it seems that code that needs to stay within a memory\\nlimit only needs to track what's been allocated in chunks within a\\nblock, since writing there is what invokes a page fault.\\n---\\n\\nIIUC you suggested measuring memory usage by tracking how much memory\\nchunks are allocated within a block. If your idea at the top of the\\npage follows this method, it still doesn't deal with the point Andres\\nmentioned.\\n\\n> I'll put this item and a couple other things together in a separate email tomorrow.\\n\\nThanks!\\n\\nRegards,\\n\\n[1] https://www.postgresql.org/message-id/CAFBsxsEnzivaJ13iCGdDoUMsXJVGOaahuBe_y%3Dq6ow%3DLTzyDvA%40mail.gmail.com\\n\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 15 Mar 2023 11:32:06 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> >\\n> > I wrote:\\n> >\\n> > > > > Since the block-level measurement is likely overestimating quite\\na bit, I propose to simply reverse the order of the actions here,\\neffectively reporting progress for the *last page* and not the current one:\\nFirst update progress with the current memory usage, then add tids for this\\npage. If this allocated a new block, only a small bit of that will be\\nwritten to. If this block pushes it over the limit, we will detect that up\\nat the top of the loop. It's kind of like our earlier attempts at a \\\"fudge\\nfactor\\\", but simpler and less brittle. And, as far as OS pages we have\\nactually written to, I think it'll effectively respect the memory limit, at\\nleast in the local mem case. And the numbers will make sense.\\n\\n> > I still like my idea at the top of the page -- at least for vacuum and\\nm_w_m. It's still not completely clear if it's right but I've got nothing\\nbetter. It also ignores the work_mem issue, but I've given up anticipating\\nall future cases at the moment.\\n\\n> IIUC you suggested measuring memory usage by tracking how much memory\\n> chunks are allocated within a block. If your idea at the top of the\\n> page follows this method, it still doesn't deal with the point Andres\\n> mentioned.\\n\\nRight, but that idea was orthogonal to how we measure memory use, and in\\nfact mentions blocks specifically. The re-ordering was just to make sure\\nthat progress reporting didn't show current-use > max-use.\\n\\nHowever, the big question remains DSA, since a new segment can be as large\\nas the entire previous set of allocations. It seems it just wasn't designed\\nfor things where memory growth is unpredictable.\\n\\nI'm starting to wonder if we need to give DSA a bit more info at the start.\\nImagine a \\\"soft\\\" limit given to the DSA area when it is initialized. If the\\ntotal segment usage exceeds this, it stops doubling and instead new\\nsegments get smaller. Modifying an example we used for the fudge-factor\\nidea some time ago:\\n\\nm_w_m = 1GB, so calculate the soft limit to be 512MB and pass it to the DSA\\narea.\\n\\n2*(1+2+4+8+16+32+64+128) + 256 = 766MB (74.8% of 1GB) -> hit soft limit, so\\n\\\"stairstep down\\\" the new segment sizes:\\n\\n766 + 2*(128) + 64 = 1086MB -> stop\\n\\nThat's just an undeveloped idea, however, so likely v17 development, even\\nassuming it's not a bad idea (could be).\\n\\nAnd sadly, unless we find some other, simpler answer soon for tracking and\\nlimiting shared memory, the tid store is looking like v17 material.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> On Tue, Mar 14, 2023 at 8:27 PM John Naylor> <john.naylor@enterprisedb.com> wrote:> >> > I wrote:> >> > > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.> > I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.> IIUC you suggested measuring memory usage by tracking how much memory> chunks are allocated within a block. If your idea at the top of the> page follows this method, it still doesn't deal with the point Andres> mentioned.Right, but that idea was orthogonal to how we measure memory use, and in fact mentions blocks specifically. The re-ordering was just to make sure that progress reporting didn't show current-use > max-use.However, the big question remains DSA, since a new segment can be as large as the entire previous set of allocations. It seems it just wasn't designed for things where memory growth is unpredictable.I'm starting to wonder if we need to give DSA a bit more info at the start. Imagine a \\\"soft\\\" limit given to the DSA area when it is initialized. If the total segment usage exceeds this, it stops doubling and instead new segments get smaller. Modifying an example we used for the fudge-factor idea some time ago:m_w_m = 1GB, so calculate the soft limit to be 512MB and pass it to the DSA area.2*(1+2+4+8+16+32+64+128) + 256 = 766MB (74.8% of 1GB) -> hit soft limit, so \\\"stairstep down\\\" the new segment sizes:766 + 2*(128) + 64 = 1086MB -> stopThat's just an undeveloped idea, however, so likely v17 development, even assuming it's not a bad idea (could be).And sadly, unless we find some other, simpler answer soon for tracking and limiting shared memory, the tid store is looking like v17 material.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Fri, 17 Mar 2023 14:02:53 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 17, 2023 at 4:03 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n> > <john.naylor@enterprisedb.com> wrote:\\n> > >\\n> > > I wrote:\\n> > >\\n> > > > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.\\n>\\n> > > I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.\\n>\\n> > IIUC you suggested measuring memory usage by tracking how much memory\\n> > chunks are allocated within a block. If your idea at the top of the\\n> > page follows this method, it still doesn't deal with the point Andres\\n> > mentioned.\\n>\\n> Right, but that idea was orthogonal to how we measure memory use, and in fact mentions blocks specifically. The re-ordering was just to make sure that progress reporting didn't show current-use > max-use.\\n\\nRight. I still like your re-ordering idea. It's true that the most\\narea of the last allocated block before heap scanning stops is not\\nactually used yet. I'm guessing we can just check if the context\\nmemory has gone over the limit. But I'm concerned it might not work\\nwell in systems where overcommit memory is disabled.\\n\\n>\\n> However, the big question remains DSA, since a new segment can be as large as the entire previous set of allocations. It seems it just wasn't designed for things where memory growth is unpredictable.\\n>\\n> I'm starting to wonder if we need to give DSA a bit more info at the start. Imagine a \\\"soft\\\" limit given to the DSA area when it is initialized. If the total segment usage exceeds this, it stops doubling and instead new segments get smaller. Modifying an example we used for the fudge-factor idea some time ago:\\n>\\n> m_w_m = 1GB, so calculate the soft limit to be 512MB and pass it to the DSA area.\\n>\\n> 2*(1+2+4+8+16+32+64+128) + 256 = 766MB (74.8% of 1GB) -> hit soft limit, so \\\"stairstep down\\\" the new segment sizes:\\n>\\n> 766 + 2*(128) + 64 = 1086MB -> stop\\n>\\n> That's just an undeveloped idea, however, so likely v17 development, even assuming it's not a bad idea (could be).\\n\\nThis is an interesting idea. But I'm concerned we don't have enough\\ntime to get confident with adding this new concept to DSA.\\n\\n>\\n> And sadly, unless we find some other, simpler answer soon for tracking and limiting shared memory, the tid store is looking like v17 material.\\n\\nAnother problem we need to deal with is the supported minimum memory\\nin shared tidstore cases. Since the initial DSA segment size is 1MB,\\nmemory usage of a shared tidstore will start from 1MB+. This is higher\\nthan the minimum values of both work_mem and maintenance_work_mem,\\n64kB and 1MB respectively. Increasing the minimum m_w_m to 2MB seems\\nto be acceptable in the community but not for work_mem. One idea is to\\ndeny the memory limit less than 2MB so it won't work with small m_w_m\\nsettings. While it might be an acceptable restriction at this stage\\n(where there is no use case of using tidstore with work_mem in the\\ncore) but it will be a blocker for the future adoptions such as\\nunifying with tidbitmap.c. Another idea is that the process can\\nspecify the initial segment size at dsa_create() so that DSA can start\\nwith a smaller segment, say 32kB. That way, a tidstore with a 32kB\\nlimit gets full once it allocates the next DSA segment, 32kB. . But a\\ndownside of this idea is to increase the number of segments behind\\nDSA. Assuming it's a relatively rare case where we use such a low\\nwork_mem, it might be acceptable. FYI, the total number of DSM\\nsegments available on the system is calculated by:\\n\\n#define PG_DYNSHMEM_FIXED_SLOTS 64\\n#define PG_DYNSHMEM_SLOTS_PER_BACKEND 5\\n\\nmaxitems = PG_DYNSHMEM_FIXED_SLOTS\\n + PG_DYNSHMEM_SLOTS_PER_BACKEND * MaxBackends;\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 17 Mar 2023 16:49:33 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 17, 2023 at 4:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Mar 17, 2023 at 4:03 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> >\\n> > On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n> > > <john.naylor@enterprisedb.com> wrote:\\n> > > >\\n> > > > I wrote:\\n> > > >\\n> > > > > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.\\n> >\\n> > > > I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.\\n> >\\n> > > IIUC you suggested measuring memory usage by tracking how much memory\\n> > > chunks are allocated within a block. If your idea at the top of the\\n> > > page follows this method, it still doesn't deal with the point Andres\\n> > > mentioned.\\n> >\\n> > Right, but that idea was orthogonal to how we measure memory use, and in fact mentions blocks specifically. The re-ordering was just to make sure that progress reporting didn't show current-use > max-use.\\n>\\n> Right. I still like your re-ordering idea. It's true that the most\\n> area of the last allocated block before heap scanning stops is not\\n> actually used yet. I'm guessing we can just check if the context\\n> memory has gone over the limit. But I'm concerned it might not work\\n> well in systems where overcommit memory is disabled.\\n>\\n> >\\n> > However, the big question remains DSA, since a new segment can be as large as the entire previous set of allocations. It seems it just wasn't designed for things where memory growth is unpredictable.\\n\\naset.c also has a similar characteristic; allocates an 8K block upon\\nthe first allocation in a context, and doubles that size for each\\nsuccessive block request. But we can specify the initial block size\\nand max blocksize. This made me think of another idea to specify both\\nto DSA and both values are calculated based on m_w_m. For example, we\\ncan create a DSA in parallel_vacuum_init() as follows:\\n\\ninitial block size = min(m_w_m / 4, 1MB)\\nmax block size = max(m_w_m / 8, 8MB)\\n\\nIn most cases, we can start with a 1MB initial segment, the same as\\nbefore. For small memory cases, say 1MB, we start with a 256KB initial\\nsegment and heap scanning stops after DSA allocated 1.5MB (= 256kB +\\n256kB + 512kB + 512kB). For larger memory, we can have heap scan stop\\nafter DSA allocates 1.25 times more memory than m_w_m. For example, if\\nm_w_m = 1GB, the both initial and maximum segment sizes are 1MB and\\n128MB respectively, and then DSA allocates the segments as follows\\nuntil heap scanning stops:\\n\\n2 * (1 + 2 + 4 + 8 + 16 + 32 + 64 + 128) + (128 * 5) = 1150MB\\n\\ndsa_allocate() will be extended to have the initial and maximum block\\nsizes like AllocSetContextCreate().\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 20 Mar 2023 14:24:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 20, 2023 at 12:25 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> On Fri, Mar 17, 2023 at 4:49 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n> >\\n> > On Fri, Mar 17, 2023 at 4:03 PM John Naylor\\n> > <john.naylor@enterprisedb.com> wrote:\\n> > >\\n> > > On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n> > > >\\n> > > > On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n> > > > <john.naylor@enterprisedb.com> wrote:\\n> > > > >\\n> > > > > I wrote:\\n> > > > >\\n> > > > > > > > Since the block-level measurement is likely overestimating\\nquite a bit, I propose to simply reverse the order of the actions here,\\neffectively reporting progress for the *last page* and not the current one:\\nFirst update progress with the current memory usage, then add tids for this\\npage. If this allocated a new block, only a small bit of that will be\\nwritten to. If this block pushes it over the limit, we will detect that up\\nat the top of the loop. It's kind of like our earlier attempts at a \\\"fudge\\nfactor\\\", but simpler and less brittle. And, as far as OS pages we have\\nactually written to, I think it'll effectively respect the memory limit, at\\nleast in the local mem case. And the numbers will make sense.\\n> > >\\n> > > > > I still like my idea at the top of the page -- at least for\\nvacuum and m_w_m. It's still not completely clear if it's right but I've\\ngot nothing better. It also ignores the work_mem issue, but I've given up\\nanticipating all future cases at the moment.\\n> > >\\n> > > > IIUC you suggested measuring memory usage by tracking how much\\nmemory\\n> > > > chunks are allocated within a block. If your idea at the top of the\\n> > > > page follows this method, it still doesn't deal with the point\\nAndres\\n> > > > mentioned.\\n> > >\\n> > > Right, but that idea was orthogonal to how we measure memory use, and\\nin fact mentions blocks specifically. The re-ordering was just to make sure\\nthat progress reporting didn't show current-use > max-use.\\n> >\\n> > Right. I still like your re-ordering idea. It's true that the most\\n> > area of the last allocated block before heap scanning stops is not\\n> > actually used yet. I'm guessing we can just check if the context\\n> > memory has gone over the limit. But I'm concerned it might not work\\n> > well in systems where overcommit memory is disabled.\\n> >\\n> > >\\n> > > However, the big question remains DSA, since a new segment can be as\\nlarge as the entire previous set of allocations. It seems it just wasn't\\ndesigned for things where memory growth is unpredictable.\\n>\\n> aset.c also has a similar characteristic; allocates an 8K block upon\\n> the first allocation in a context, and doubles that size for each\\n> successive block request. But we can specify the initial block size\\n> and max blocksize. This made me think of another idea to specify both\\n> to DSA and both values are calculated based on m_w_m. For example, we\\n\\nThat's an interesting idea, and the analogous behavior to aset could be a\\ngood thing for readability and maintainability. Worth seeing if it's\\nworkable.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Mar 20, 2023 at 12:25 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> On Fri, Mar 17, 2023 at 4:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:> >> > On Fri, Mar 17, 2023 at 4:03 PM John Naylor> > <john.naylor@enterprisedb.com> wrote:> > >> > > On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:> > > >> > > > On Tue, Mar 14, 2023 at 8:27 PM John Naylor> > > > <john.naylor@enterprisedb.com> wrote:> > > > >> > > > > I wrote:> > > > >> > > > > > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.> > >> > > > > I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.> > >> > > > IIUC you suggested measuring memory usage by tracking how much memory> > > > chunks are allocated within a block. If your idea at the top of the> > > > page follows this method, it still doesn't deal with the point Andres> > > > mentioned.> > >> > > Right, but that idea was orthogonal to how we measure memory use, and in fact mentions blocks specifically. The re-ordering was just to make sure that progress reporting didn't show current-use > max-use.> >> > Right. I still like your re-ordering idea. It's true that the most> > area of the last allocated block before heap scanning stops is not> > actually used yet. I'm guessing we can just check if the context> > memory has gone over the limit. But I'm concerned it might not work> > well in systems where overcommit memory is disabled.> >> > >> > > However, the big question remains DSA, since a new segment can be as large as the entire previous set of allocations. It seems it just wasn't designed for things where memory growth is unpredictable.>> aset.c also has a similar characteristic; allocates an 8K block upon> the first allocation in a context, and doubles that size for each> successive block request. But we can specify the initial block size> and max blocksize. This made me think of another idea to specify both> to DSA and both values are calculated based on m_w_m. For example, weThat's an interesting idea, and the analogous behavior to aset could be a good thing for readability and maintainability. Worth seeing if it's workable.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 20 Mar 2023 19:33:56 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 20, 2023 at 9:34 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> On Mon, Mar 20, 2023 at 12:25 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Mar 17, 2023 at 4:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Fri, Mar 17, 2023 at 4:03 PM John Naylor\\n> > > <john.naylor@enterprisedb.com> wrote:\\n> > > >\\n> > > > On Wed, Mar 15, 2023 at 9:32 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > > >\\n> > > > > On Tue, Mar 14, 2023 at 8:27 PM John Naylor\\n> > > > > <john.naylor@enterprisedb.com> wrote:\\n> > > > > >\\n> > > > > > I wrote:\\n> > > > > >\\n> > > > > > > > > Since the block-level measurement is likely overestimating quite a bit, I propose to simply reverse the order of the actions here, effectively reporting progress for the *last page* and not the current one: First update progress with the current memory usage, then add tids for this page. If this allocated a new block, only a small bit of that will be written to. If this block pushes it over the limit, we will detect that up at the top of the loop. It's kind of like our earlier attempts at a \\\"fudge factor\\\", but simpler and less brittle. And, as far as OS pages we have actually written to, I think it'll effectively respect the memory limit, at least in the local mem case. And the numbers will make sense.\\n> > > >\\n> > > > > > I still like my idea at the top of the page -- at least for vacuum and m_w_m. It's still not completely clear if it's right but I've got nothing better. It also ignores the work_mem issue, but I've given up anticipating all future cases at the moment.\\n> > > >\\n> > > > > IIUC you suggested measuring memory usage by tracking how much memory\\n> > > > > chunks are allocated within a block. If your idea at the top of the\\n> > > > > page follows this method, it still doesn't deal with the point Andres\\n> > > > > mentioned.\\n> > > >\\n> > > > Right, but that idea was orthogonal to how we measure memory use, and in fact mentions blocks specifically. The re-ordering was just to make sure that progress reporting didn't show current-use > max-use.\\n> > >\\n> > > Right. I still like your re-ordering idea. It's true that the most\\n> > > area of the last allocated block before heap scanning stops is not\\n> > > actually used yet. I'm guessing we can just check if the context\\n> > > memory has gone over the limit. But I'm concerned it might not work\\n> > > well in systems where overcommit memory is disabled.\\n> > >\\n> > > >\\n> > > > However, the big question remains DSA, since a new segment can be as large as the entire previous set of allocations. It seems it just wasn't designed for things where memory growth is unpredictable.\\n> >\\n> > aset.c also has a similar characteristic; allocates an 8K block upon\\n> > the first allocation in a context, and doubles that size for each\\n> > successive block request. But we can specify the initial block size\\n> > and max blocksize. This made me think of another idea to specify both\\n> > to DSA and both values are calculated based on m_w_m. For example, we\\n>\\n> That's an interesting idea, and the analogous behavior to aset could be a good thing for readability and maintainability. Worth seeing if it's workable.\\n\\nI've attached a quick hack patch. It can be applied on top of v32\\npatches. The changes to dsa.c are straightforward since it makes the\\ninitial and max block sizes configurable. The patch includes a test\\nfunction, test_memory_usage() to simulate how DSA segments grow behind\\nthe shared radix tree. If we set the first argument to true, it\\ncalculates both initial and maximum block size based on work_mem (I\\nused work_mem here just because its value range is larger than m_w_m):\\n\\npostgres(1:833654)=# select test_memory_usage(true);\\nNOTICE: memory limit 134217728\\nNOTICE: init 1048576 max 16777216\\nNOTICE: initial: 1048576\\nNOTICE: rt_create: 1048576\\nNOTICE: allocate new DSM [1] 1048576\\nNOTICE: allocate new DSM [2] 2097152\\nNOTICE: allocate new DSM [3] 2097152\\nNOTICE: allocate new DSM [4] 4194304\\nNOTICE: allocate new DSM [5] 4194304\\nNOTICE: allocate new DSM [6] 8388608\\nNOTICE: allocate new DSM [7] 8388608\\nNOTICE: allocate new DSM [8] 16777216\\nNOTICE: allocate new DSM [9] 16777216\\nNOTICE: allocate new DSM [10] 16777216\\nNOTICE: allocate new DSM [11] 16777216\\nNOTICE: allocate new DSM [12] 16777216\\nNOTICE: allocate new DSM [13] 16777216\\nNOTICE: allocate new DSM [14] 16777216\\nNOTICE: reached: 148897792 (+14680064)\\nNOTICE: 12718205 keys inserted: 148897792\\n test_memory_usage\\n-------------------\\n\\n(1 row)\\n\\nTime: 7195.664 ms (00:07.196)\\n\\nSetting the first argument to false, we can specify both manually in\\nsecond and third arguments:\\n\\npostgres(1:833654)=# select test_memory_usage(false, 1024 * 1024, 1024\\n* 1024 * 1024 * 10::bigint);\\nNOTICE: memory limit 134217728\\nNOTICE: init 1048576 max 10737418240\\nNOTICE: initial: 1048576\\nNOTICE: rt_create: 1048576\\nNOTICE: allocate new DSM [1] 1048576\\nNOTICE: allocate new DSM [2] 2097152\\nNOTICE: allocate new DSM [3] 2097152\\nNOTICE: allocate new DSM [4] 4194304\\nNOTICE: allocate new DSM [5] 4194304\\nNOTICE: allocate new DSM [6] 8388608\\nNOTICE: allocate new DSM [7] 8388608\\nNOTICE: allocate new DSM [8] 16777216\\nNOTICE: allocate new DSM [9] 16777216\\nNOTICE: allocate new DSM [10] 33554432\\nNOTICE: allocate new DSM [11] 33554432\\nNOTICE: allocate new DSM [12] 67108864\\nNOTICE: reached: 199229440 (+65011712)\\nNOTICE: 12718205 keys inserted: 199229440\\n test_memory_usage\\n-------------------\\n\\n(1 row)\\n\\nTime: 7187.571 ms (00:07.188)\\n\\nIt seems to work fine. The differences between the above two cases is\\nthe maximum block size (16MB .vs 10GB). We allocated two more DSA\\nsegments in the first segments but there was no big difference in the\\nperformance in my test environment.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 20 Mar 2023 23:34:08 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 20, 2023 at 9:34 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> On Mon, Mar 20, 2023 at 9:34 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> > That's an interesting idea, and the analogous behavior to aset could be\\na good thing for readability and maintainability. Worth seeing if it's\\nworkable.\\n>\\n> I've attached a quick hack patch. It can be applied on top of v32\\n> patches. The changes to dsa.c are straightforward since it makes the\\n> initial and max block sizes configurable.\\n\\nGood to hear -- this should probably be proposed in a separate thread for\\nwider visibility.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Mar 20, 2023 at 9:34 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> On Mon, Mar 20, 2023 at 9:34 PM John Naylor> <john.naylor@enterprisedb.com> wrote:> > That's an interesting idea, and the analogous behavior to aset could be a good thing for readability and maintainability. Worth seeing if it's workable.>> I've attached a quick hack patch. It can be applied on top of v32> patches. The changes to dsa.c are straightforward since it makes the> initial and max block sizes configurable.Good to hear -- this should probably be proposed in a separate thread for wider visibility.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 21 Mar 2023 12:41:26 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 21, 2023 at 2:41 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> On Mon, Mar 20, 2023 at 9:34 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 20, 2023 at 9:34 PM John Naylor\\n> > <john.naylor@enterprisedb.com> wrote:\\n> > > That's an interesting idea, and the analogous behavior to aset could be a good thing for readability and maintainability. Worth seeing if it's workable.\\n> >\\n> > I've attached a quick hack patch. It can be applied on top of v32\\n> > patches. The changes to dsa.c are straightforward since it makes the\\n> > initial and max block sizes configurable.\\n>\\n> Good to hear -- this should probably be proposed in a separate thread for wider visibility.\\n\\nAgreed. I'll start a new thread for that.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 21 Mar 2023 15:37:23 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Feb 16, 2023 at 11:44 PM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> We really ought to replace the tid bitmap used for bitmap heap scans. The\\n> hashtable we use is a pretty awful data structure for it. And that's not\\n> filled in-order, for example.\\n\\nI spent some time studying tidbitmap.c, and not only does it make sense to\\nuse a radix tree there, but since it has more complex behavior and stricter\\nruntime requirements, it should really be the thing driving the design and\\ntradeoffs, not vacuum:\\n\\n- With lazy expansion and single-value leaves, the root of a radix tree can\\npoint to a single leaf. That might get rid of the need to track TBMStatus,\\nsince setting a single-leaf tree should be cheap.\\n\\n- Fixed-size PagetableEntry's are pretty large, but the tid compression\\nscheme used in this thread (in addition to being complex) is not a great\\nfit for tidbitmap because it makes it more difficult to track per-block\\nmetadata (see also next point). With the \\\"combined pointer-value slots\\\"\\ntechnique, if a page's max tid offset is 63 or less, the offsets can be\\nstored directly in the pointer for the exact case. The lowest bit can tag\\nto indicate a pointer to a single-value leaf. That would complicate\\noperations like union/intersection and tracking \\\"needs recheck\\\", but it\\nwould reduce memory use and node-traversal in common cases.\\n\\n- Managing lossy storage. With pure blocknumber keys, replacing exact\\nstorage for a range of 256 pages amounts to replacing a last-level node\\nwith a single leaf containing one lossy PagetableEntry. The leader could\\niterate over the nodes, and rank the last-level nodes by how much storage\\nthey (possibly with leaf children) are using, and come up with an optimal\\nlossy-conversion plan.\\n\\nThe above would address the points (not including better iteration and\\nparallel bitmap index scans) raised in\\n\\nhttps://www.postgresql.org/message-id/CAPsAnrn5yWsoWs8GhqwbwAJx1SeLxLntV54Biq0Z-J_E86Fnng@mail.gmail.com\\n\\nIronically, by targeting a more difficult use case, it's easier since there\\nis less freedom. There are many ways to beat a binary search, but fewer\\ngood ways to improve bitmap heap scan. I'd like to put aside vacuum for\\nsome time and try killing two birds with one stone, building upon our work\\nthus far.\\n\\nNote: I've moved the CF entry to the next CF, and set to waiting on\\nauthor for now. Since no action is currently required from Masahiko, I've\\nadded myself as author as well. If tackling bitmap heap scan shows promise,\\nwe could RWF and resurrect at a later time.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Thu, Feb 16, 2023 at 11:44 PM Andres Freund <andres@anarazel.de> wrote:>> We really ought to replace the tid bitmap used for bitmap heap scans. The> hashtable we use is a pretty awful data structure for it. And that's not> filled in-order, for example.I spent some time studying tidbitmap.c, and not only does it make sense to use a radix tree there, but since it has more complex behavior and stricter runtime requirements, it should really be the thing driving the design and tradeoffs, not vacuum:- With lazy expansion and single-value leaves, the root of a radix tree can point to a single leaf. That might get rid of the need to track TBMStatus, since setting a single-leaf tree should be cheap.- Fixed-size PagetableEntry's are pretty large, but the tid compression scheme used in this thread (in addition to being complex) is not a great fit for tidbitmap because it makes it more difficult to track per-block metadata (see also next point). With the \\\"combined pointer-value slots\\\" technique, if a page's max tid offset is 63 or less, the offsets can be stored directly in the pointer for the exact case. The lowest bit can tag to indicate a pointer to a single-value leaf. That would complicate operations like union/intersection and tracking \\\"needs recheck\\\", but it would reduce memory use and node-traversal in common cases.- Managing lossy storage. With pure blocknumber keys, replacing exact storage for a range of 256 pages amounts to replacing a last-level node with a single leaf containing one lossy PagetableEntry. The leader could iterate over the nodes, and rank the last-level nodes by how much storage they (possibly with leaf children) are using, and come up with an optimal lossy-conversion plan.The above would address the points (not including better iteration and parallel bitmap index scans) raised inhttps://www.postgresql.org/message-id/CAPsAnrn5yWsoWs8GhqwbwAJx1SeLxLntV54Biq0Z-J_E86Fnng@mail.gmail.comIronically, by targeting a more difficult use case, it's easier since there is less freedom. There are many ways to beat a binary search, but fewer good ways to improve bitmap heap scan. I'd like to put aside vacuum for some time and try killing two birds with one stone, building upon our work thus far. Note: I've moved the CF entry to the next CF, and set to waiting on author for now. Since no action is currently required from Masahiko, I've added myself as author as well. If tackling bitmap heap scan shows promise, we could RWF and resurrect at a later time.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Fri, 7 Apr 2023 16:55:41 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 7, 2023 at 6:55 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n>\\n> On Thu, Feb 16, 2023 at 11:44 PM Andres Freund <andres@anarazel.de> wrote:\\n> >\\n> > We really ought to replace the tid bitmap used for bitmap heap scans. The\\n> > hashtable we use is a pretty awful data structure for it. And that's not\\n> > filled in-order, for example.\\n>\\n> I spent some time studying tidbitmap.c, and not only does it make sense to use a radix tree there, but since it has more complex behavior and stricter runtime requirements, it should really be the thing driving the design and tradeoffs, not vacuum:\\n>\\n> - With lazy expansion and single-value leaves, the root of a radix tree can point to a single leaf. That might get rid of the need to track TBMStatus, since setting a single-leaf tree should be cheap.\\n>\\n\\nInstead of introducing single-value leaves to the radix tree as\\nanother structure, can we store pointers to PagetableEntry as values?\\n\\n> - Fixed-size PagetableEntry's are pretty large, but the tid compression scheme used in this thread (in addition to being complex) is not a great fit for tidbitmap because it makes it more difficult to track per-block metadata (see also next point). With the \\\"combined pointer-value slots\\\" technique, if a page's max tid offset is 63 or less, the offsets can be stored directly in the pointer for the exact case. The lowest bit can tag to indicate a pointer to a single-value leaf. That would complicate operations like union/intersection and tracking \\\"needs recheck\\\", but it would reduce memory use and node-traversal in common cases.\\n>\\n> - Managing lossy storage. With pure blocknumber keys, replacing exact storage for a range of 256 pages amounts to replacing a last-level node with a single leaf containing one lossy PagetableEntry. The leader could iterate over the nodes, and rank the last-level nodes by how much storage they (possibly with leaf children) are using, and come up with an optimal lossy-conversion plan.\\n>\\n> The above would address the points (not including better iteration and parallel bitmap index scans) raised in\\n>\\n> https://www.postgresql.org/message-id/CAPsAnrn5yWsoWs8GhqwbwAJx1SeLxLntV54Biq0Z-J_E86Fnng@mail.gmail.com\\n>\\n> Ironically, by targeting a more difficult use case, it's easier since there is less freedom. There are many ways to beat a binary search, but fewer good ways to improve bitmap heap scan. I'd like to put aside vacuum for some time and try killing two birds with one stone, building upon our work thus far.\\n>\\n> Note: I've moved the CF entry to the next CF, and set to waiting on author for now. Since no action is currently required from Masahiko, I've added myself as author as well. If tackling bitmap heap scan shows promise, we could RWF and resurrect at a later time.\\n\\nThanks. I'm going to continue researching the memory limitation and\\ntry lazy path expansion until PG17 development begins.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 17 Apr 2023 22:48:27 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sat, Mar 11, 2023 at 12:26 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Mar 10, 2023 at 11:30 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Mar 10, 2023 at 3:42 PM John Naylor\\n> > <john.naylor@enterprisedb.com> wrote:\\n> > >\\n> > > On Thu, Mar 9, 2023 at 1:51 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > I've attached the new version patches. I merged improvements and fixes\\n> > > > I did in the v29 patch.\\n> > >\\n> > > I haven't yet had a chance to look at those closely, since I've had to devote time to other commitments. I remember I wasn't particularly impressed that v29-0008 mixed my requested name-casing changes with a bunch of other random things. Separating those out would be an obvious way to make it easier for me to look at, whenever I can get back to this. I need to look at the iteration changes as well, in addition to testing memory measurement (thanks for the new results, they look encouraging).\\n> >\\n> > Okay, I'll separate them again.\\n>\\n> Attached new patch series. In addition to separate them again, I've\\n> fixed a conflict with HEAD.\\n>\\n\\nI've attached updated version patches to make cfbot happy. Also, I've\\nsplitted fixup patches further(from 0007 except for 0016 and 0018) to\\nmake reviews easy. These patches have the prefix radix tree, tidstore,\\nand vacuum, indicating the part it changes. 0016 patch is to change\\nDSA so that we can specify both the initial and max segment size and\\n0017 makes use of it in vacuumparallel.c I'm still researching a\\nbetter solution for memory limitation but it's the best solution for\\nme for now.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 18 Apr 2023 00:20:16 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 17, 2023 at 8:49 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n\\n> > - With lazy expansion and single-value leaves, the root of a radix tree\\ncan point to a single leaf. That might get rid of the need to track\\nTBMStatus, since setting a single-leaf tree should be cheap.\\n> >\\n>\\n> Instead of introducing single-value leaves to the radix tree as\\n> another structure, can we store pointers to PagetableEntry as values?\\n\\nWell, that's pretty much what a single-value leaf is. Now that I've had\\ntime to pause and regroup, I've looked into some aspects we previously put\\noff for future work, and this is one of them.\\n\\nThe concept is really quite trivial, and it's the simplest and most\\nflexible way to implement ART. Our, or at least my, documented reason not\\nto go that route was due to \\\"an extra pointer traversal\\\", but that's\\npartially mitigated by \\\"lazy expansion\\\", which is actually fairly easy to\\ndo with single-value leaves. The two techniques complement each other in a\\nnatural way. (Path compression, on the other hand, is much more complex.)\\n\\n> > Note: I've moved the CF entry to the next CF, and set to waiting on\\nauthor for now. Since no action is currently required from Masahiko, I've\\nadded myself as author as well. If tackling bitmap heap scan shows promise,\\nwe could RWF and resurrect at a later time.\\n>\\n> Thanks. I'm going to continue researching the memory limitation and\\n\\nSounds like the best thing to nail down at this point.\\n\\n> try lazy path expansion until PG17 development begins.\\n\\nThis doesn't seem like a useful thing to try and attach into the current\\npatch (if that's what you mean), as the current insert/delete paths are\\nquite complex. Using bitmap heap scan as a motivating use case, I hope to\\nrefocus complexity to where it's most needed, and aggressively simplify\\nwhere possible.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Apr 17, 2023 at 8:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:> > - With lazy expansion and single-value leaves, the root of a radix tree can point to a single leaf. That might get rid of the need to track TBMStatus, since setting a single-leaf tree should be cheap.> >>> Instead of introducing single-value leaves to the radix tree as> another structure, can we store pointers to PagetableEntry as values?Well, that's pretty much what a single-value leaf is. Now that I've had time to pause and regroup, I've looked into some aspects we previously put off for future work, and this is one of them.The concept is really quite trivial, and it's the simplest and most flexible way to implement ART. Our, or at least my, documented reason not to go that route was due to \\\"an extra pointer traversal\\\", but that's partially mitigated by \\\"lazy expansion\\\", which is actually fairly easy to do with single-value leaves. The two techniques complement each other in a natural way. (Path compression, on the other hand, is much more complex.)> > Note: I've moved the CF entry to the next CF, and set to waiting on author for now. Since no action is currently required from Masahiko, I've added myself as author as well. If tackling bitmap heap scan shows promise, we could RWF and resurrect at a later time.>> Thanks. I'm going to continue researching the memory limitation andSounds like the best thing to nail down at this point.> try lazy path expansion until PG17 development begins.This doesn't seem like a useful thing to try and attach into the current patch (if that's what you mean), as the current insert/delete paths are quite complex. Using bitmap heap scan as a motivating use case, I hope to refocus complexity to where it's most needed, and aggressively simplify where possible.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 19 Apr 2023 14:02:14 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Apr 19, 2023 at 4:02 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> On Mon, Apr 17, 2023 at 8:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > - With lazy expansion and single-value leaves, the root of a radix tree can point to a single leaf. That might get rid of the need to track TBMStatus, since setting a single-leaf tree should be cheap.\\n> > >\\n> >\\n> > Instead of introducing single-value leaves to the radix tree as\\n> > another structure, can we store pointers to PagetableEntry as values?\\n>\\n> Well, that's pretty much what a single-value leaf is. Now that I've had time to pause and regroup, I've looked into some aspects we previously put off for future work, and this is one of them.\\n>\\n> The concept is really quite trivial, and it's the simplest and most flexible way to implement ART. Our, or at least my, documented reason not to go that route was due to \\\"an extra pointer traversal\\\", but that's partially mitigated by \\\"lazy expansion\\\", which is actually fairly easy to do with single-value leaves. The two techniques complement each other in a natural way. (Path compression, on the other hand, is much more complex.)\\n>\\n> > > Note: I've moved the CF entry to the next CF, and set to waiting on author for now. Since no action is currently required from Masahiko, I've added myself as author as well. If tackling bitmap heap scan shows promise, we could RWF and resurrect at a later time.\\n> >\\n> > Thanks. I'm going to continue researching the memory limitation and\\n>\\n> Sounds like the best thing to nail down at this point.\\n>\\n> > try lazy path expansion until PG17 development begins.\\n>\\n> This doesn't seem like a useful thing to try and attach into the current patch (if that's what you mean), as the current insert/delete paths are quite complex. Using bitmap heap scan as a motivating use case, I hope to refocus complexity to where it's most needed, and aggressively simplify where possible.\\n>\\n\\nI agree that we don't want to make the current patch complex further.\\n\\nThinking about the memory limitation more, I think that combination of\\nthe idea of specifying the initial and max DSA segment size and\\ndsa_set_size_limit() works well. There are two points in terms of\\nmemory limitation; when the memory usage reaches the limit we want (1)\\nto minimize the last allocated memory block that is allocated but not\\nused yet and (2) to minimize the amount of memory that exceeds the\\nmemory limit. Since we can specify the maximum DSA segment size, the\\nlast allocated block before reaching the memory limit is small. Also,\\nthanks to dsa_set_size_limit(), the total DSA size will stop at the\\nlimit, so (memory_usage >= memory_limit) returns true without any\\nexceeding memory.\\n\\nGiven that we need to configure the initial and maximum DSA segment\\nsize and set the DSA limit for TidStore memory accounting and\\nlimiting, it would be better to create the DSA for TidStore by\\nTidStoreCreate() API, rather than creating DSA in the caller and pass\\nit to TidStoreCreate().\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 24 Apr 2023 14:45:04 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Apr 7, 2023 at 4:55 PM John Naylor <john.naylor@enterprisedb.com>\\nwrote:\\n\\n> - Fixed-size PagetableEntry's are pretty large, but the tid compression\\nscheme used in this thread (in addition to being complex) is not a great\\nfit for tidbitmap because it makes it more difficult to track per-block\\nmetadata (see also next point). With the \\\"combined pointer-value slots\\\"\\ntechnique, if a page's max tid offset is 63 or less, the offsets can be\\nstored directly in the pointer for the exact case. The lowest bit can tag\\nto indicate a pointer to a single-value leaf. That would complicate\\noperations like union/intersection and tracking \\\"needs recheck\\\", but it\\nwould reduce memory use and node-traversal in common cases.\\n\\n[just getting some thoughts out there before I have something concrete]\\n\\nThinking some more, this needn't be complicated at all. We'd just need to\\nreserve some bits of a bitmapword for the tag, as well as flags for\\n\\\"ischunk\\\" and \\\"recheck\\\". The other bits can be used for offsets.\\nGetting/storing the offsets basically amounts to adjusting the shift by a\\nconstant. That way, this \\\"embeddable PTE\\\" could serve as both \\\"PTE embedded\\nin a node pointer\\\" and also the first member of a full PTE. A full PTE is\\nnow just an array of embedded PTEs, except only the first one has the flags\\nwe need. That reduces the number of places that have to be different.\\nStoring any set of offsets all less than ~60 would save\\nallocation/traversal in a large number of real cases. Furthermore, that\\nwould reduce a full PTE to 40 bytes because there would be no padding.\\n\\nThis all assumes the key (block number) is no longer stored in the PTE,\\nwhether embedded or not. That would mean this technique:\\n\\n> - With lazy expansion and single-value leaves, the root of a radix tree\\ncan point to a single leaf. That might get rid of the need to track\\nTBMStatus, since setting a single-leaf tree should be cheap.\\n\\n...is not a good trade off because it requires each leaf to have the key,\\nand would thus reduce the utility of embedded leaves. We just need to make\\nsure storing a single value is not costly, and I suspect it's not.\\n(Currently the overhead avoided is allocating and zeroing a few kilobytes\\nfor a hash table). If it is not, then we don't need a special case in\\ntidbitmap, which would be a great simplification. If it is, there are other\\nways to mitigate.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Fri, Apr 7, 2023 at 4:55 PM John Naylor <john.naylor@enterprisedb.com> wrote:> - Fixed-size PagetableEntry's are pretty large, but the tid compression scheme used in this thread (in addition to being complex) is not a great fit for tidbitmap because it makes it more difficult to track per-block metadata (see also next point). With the \\\"combined pointer-value slots\\\" technique, if a page's max tid offset is 63 or less, the offsets can be stored directly in the pointer for the exact case. The lowest bit can tag to indicate a pointer to a single-value leaf. That would complicate operations like union/intersection and tracking \\\"needs recheck\\\", but it would reduce memory use and node-traversal in common cases.[just getting some thoughts out there before I have something concrete]Thinking some more, this needn't be complicated at all. We'd just need to reserve some bits of a bitmapword for the tag, as well as flags for \\\"ischunk\\\" and \\\"recheck\\\". The other bits can be used for offsets. Getting/storing the offsets basically amounts to adjusting the shift by a constant. That way, this \\\"embeddable PTE\\\" could serve as both \\\"PTE embedded in a node pointer\\\" and also the first member of a full PTE. A full PTE is now just an array of embedded PTEs, except only the first one has the flags we need. That reduces the number of places that have to be different. Storing any set of offsets all less than ~60 would save allocation/traversal in a large number of real cases. Furthermore, that would reduce a full PTE to 40 bytes because there would be no padding.This all assumes the key (block number) is no longer stored in the PTE, whether embedded or not. That would mean this technique:> - With lazy expansion and single-value leaves, the root of a radix tree can point to a single leaf. That might get rid of the need to track TBMStatus, since setting a single-leaf tree should be cheap....is not a good trade off because it requires each leaf to have the key, and would thus reduce the utility of embedded leaves. We just need to make sure storing a single value is not costly, and I suspect it's not. (Currently the overhead avoided is allocating and zeroing a few kilobytes for a hash table). If it is not, then we don't need a special case in tidbitmap, which would be a great simplification. If it is, there are other ways to mitigate.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 8 May 2023 17:23:23 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n> the current insert/delete paths are quite complex. Using bitmap heap scan\\nas a motivating use case, I hope to refocus complexity to where it's most\\nneeded, and aggressively simplify where possible.\\n\\nSometime in the not-too-distant future, I will start a new thread focusing\\non bitmap heap scan, but for now, I just want to share some progress on\\nmaking the radix tree usable not only for that, but hopefully a wider range\\nof applications, while making the code simpler and the binary smaller. The\\nattached patches are incomplete (e.g. no iteration) and quite a bit messy,\\nso tar'd and gzip'd for the curious (should apply on top of v32 0001-03 +\\n0007-09 ).\\n\\n0001\\n\\nThis combines a few concepts that I didn't bother separating out after the\\nfact:\\n- Split insert_impl.h into multiple functions for improved readability and\\nmaintainability.\\n- Use single-value leaves as the basis for storing values, with the goal to\\nget to \\\"combined pointer-value slots\\\" for efficiency and flexibility.\\n- With the latter in mind, searching the child within a node now returns\\nthe address of the slot. This allows the same interface whether the slot\\ncontains a child pointer or a value.\\n- Starting with RT_SET, start turning some iterative algorithms into\\nrecursive ones. This is a more natural way to traverse a tree structure,\\nand we already see an advantage: Previously when growing a node, we\\nsearched within the parent to update its reference to the new node, because\\nwe didn't know the slot we descended from. Now we can simply update a\\nsingle variable.\\n- Since we recursively pass the \\\"shift\\\" down the stack, it doesn't have to\\nbe stored in any node -- only the \\\"top-level\\\" start shift is stored in the\\ntree control struct. This was easy to code since the node's shift value was\\nhardly ever accessed anyway! The node header shrinks from 5 bytes to 4.\\n\\n0002\\n\\nBack in v15, we tried keeping DSA/local pointers as members of a struct. I\\ndid not like the result, but still thought it was a good idea. RT_DELETE is\\na complex function and I didn't want to try rewriting it without a pointer\\nabstraction, so I've resurrected this idea, but in a simpler, less\\nintrusive way. A key difference from v15 is using a union type for the\\nnon-shmem case.\\n\\n0004\\n\\nRewrite RT_DELETE using recursion. I find this simpler than the previous\\nopen-coded stack.\\n\\n0005-06\\n\\nDeletion has an inefficiency: One function searches for the child to see if\\nit's there, then another function searches for it again to delete it. Since\\n0001, a successful child search returns the address of the slot, so we can\\nsave it. For the two smaller \\\"linear search\\\" node kinds we can then use a\\nsingle subtraction to compute the chunk/slot index for deletion. Also,\\nsplit RT_NODE_DELETE_INNER into separate functions, for a similar reason as\\nthe insert case in 0001.\\n\\n0007\\n\\nAnticipate node shrinking: If only one node-kind needs to be freed, we can\\nmove a branch to that one code path, rather than every place where RT_FREE\\nis inlined.\\n\\n0009\\n\\nTeach node256 how to shrink *. Since we know the number of children in a\\nnode256 can't possibly be zero, we can use uint8 to store the count and\\ninterpret an overflow to zero as 256 for this node. The node header shrinks\\nfrom 4 bytes to 3.\\n\\n* Other nodes will follow in due time, but only after I figure out how to\\ndo it nicely (ideas welcome!) -- currently node32's two size classes work\\nfine for growing, but the code should be simplified before extending to\\nother cases.)\\n\\n0010\\n\\nLimited support for \\\"combined pointer-value slots\\\". At compile-time, choose\\neither that or \\\"single-value leaves\\\" based on the size of the value type\\ntemplate parameter. Values that are pointer-sized or less can fit in the\\nlast-level child slots of nominal \\\"inner nodes\\\" without duplicated\\nleaf-node code. Node256 now must act like the previous 'node256 leaf',\\nsince zero is a valid value. Aside from that, this was a small change.\\n\\nWhat I've shared here could work (in principal, since it uses uint64\\nvalues) for tidstore, possibly faster (untested) because of better code\\ndensity, but as mentioned I want to shoot for higher. For tidbitmap.c, I\\nwant to extend this idea and branch at run-time on a per-value basis, so\\nthat a page-table entry that fits in a pointer can go there, and if not,\\nit'll be a full leaf. (This technique enables more flexibility in\\nlossifying pages as well.) Run-time info will require e.g. an additional\\nbit per slot. Since the node header is now 3 bytes, we can spare one more\\nbyte in the node3 case. In addition, we can and should also bump it back up\\nto node4, still keeping the metadata within 8 bytes (no struct padding).\\n\\nI've started in this patchset to refer to the node kinds as \\\"4/16/48/256\\\",\\nregardless of their actual fanout. This is for readability (by matching the\\nlanguage in the paper) and maintainability (should *not* ever change\\nagain). The size classes (including multiple classes per kind) could be\\ndetermined by macros and #ifdef's. For example, in non-SIMD architectures,\\nit's likely slow to search an array of 32 key chunks, so in that case the\\ncompiler should choose size classes similar to these four nominal kinds.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 24 May 2023 06:16:54 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Tue, May 23, 2023 at 7:17 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> I wrote:\\n> > the current insert/delete paths are quite complex. Using bitmap heap scan as a motivating use case, I hope to refocus complexity to where it's most needed, and aggressively simplify where possible.\\n>\\n> Sometime in the not-too-distant future, I will start a new thread focusing on bitmap heap scan, but for now, I just want to share some progress on making the radix tree usable not only for that, but hopefully a wider range of applications, while making the code simpler and the binary smaller. The attached patches are incomplete (e.g. no iteration) and quite a bit messy, so tar'd and gzip'd for the curious (should apply on top of v32 0001-03 + 0007-09 ).\\n>\\n\\nThank you for making progress on this. I agree with these directions\\noverall. I have some comments and questions:\\n\\n> - With the latter in mind, searching the child within a node now returns the address of the slot. This allows the same interface whether the slot contains a child pointer or a value.\\n\\nProbably we can apply similar changes to the iteration as well.\\n\\n> * Other nodes will follow in due time, but only after I figure out how to do it nicely (ideas welcome!) -- currently node32's two size classes work fine for growing, but the code should be simplified before extending to other cases.)\\n\\nWithin the size class, we just alloc a new node of lower size class\\nand do memcpy(). I guess it will be almost same as what we do for\\ngrowing. It might be a good idea to support node shrinking within the\\nsize class for node32 (and node125 if we support). I don't think\\nshrinking class-3 to class-1 makes sense.\\n\\n>\\n> Limited support for \\\"combined pointer-value slots\\\". At compile-time, choose either that or \\\"single-value leaves\\\" based on the size of the value type template parameter. Values that are pointer-sized or less can fit in the last-level child slots of nominal \\\"inner nodes\\\" without duplicated leaf-node code. Node256 now must act like the previous 'node256 leaf', since zero is a valid value. Aside from that, this was a small change.\\n\\nYes, but it also means that we use pointer-sized value anyway even if\\nthe value size is less than that, which wastes the memory, no?\\n\\n>\\n> What I've shared here could work (in principal, since it uses uint64 values) for tidstore, possibly faster (untested) because of better code density, but as mentioned I want to shoot for higher. For tidbitmap.c, I want to extend this idea and branch at run-time on a per-value basis, so that a page-table entry that fits in a pointer can go there, and if not, it'll be a full leaf. (This technique enables more flexibility in lossifying pages as well.) Run-time info will require e.g. an additional bit per slot. Since the node header is now 3 bytes, we can spare one more byte in the node3 case. In addition, we can and should also bump it back up to node4, still keeping the metadata within 8 bytes (no struct padding).\\n\\nSounds good.\\n\\n> I've started in this patchset to refer to the node kinds as \\\"4/16/48/256\\\", regardless of their actual fanout. This is for readability (by matching the language in the paper) and maintainability (should *not* ever change again). The size classes (including multiple classes per kind) could be determined by macros and #ifdef's. For example, in non-SIMD architectures, it's likely slow to search an array of 32 key chunks, so in that case the compiler should choose size classes similar to these four nominal kinds.\\n\\nIf we want to use the node kinds used in the paper, I think we should\\nchange the number in RT_NODE_KIND_X too. Otherwise, it would be\\nconfusing when reading the code without referring to the paper.\\nParticularly, this part is very confusing:\\n\\n case RT_NODE_KIND_3:\\n RT_ADD_CHILD_4(tree, ref, node, chunk, child);\\n break;\\n case RT_NODE_KIND_32:\\n RT_ADD_CHILD_16(tree, ref, node, chunk, child);\\n break;\\n case RT_NODE_KIND_125:\\n RT_ADD_CHILD_48(tree, ref, node, chunk, child);\\n break;\\n case RT_NODE_KIND_256:\\n RT_ADD_CHILD_256(tree, ref, node, chunk, child);\\n break;\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 5 Jun 2023 06:31:41 -0400\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jun 5, 2023 at 5:32 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> > Sometime in the not-too-distant future, I will start a new thread\\nfocusing on bitmap heap scan, but for now, I just want to share some\\nprogress on making the radix tree usable not only for that, but hopefully a\\nwider range of applications, while making the code simpler and the binary\\nsmaller. The attached patches are incomplete (e.g. no iteration) and quite\\na bit messy, so tar'd and gzip'd for the curious (should apply on top of\\nv32 0001-03 + 0007-09 ).\\n> >\\n>\\n> Thank you for making progress on this. I agree with these directions\\n> overall. I have some comments and questions:\\n\\nGlad to hear it and thanks for looking!\\n\\n> > * Other nodes will follow in due time, but only after I figure out how\\nto do it nicely (ideas welcome!) -- currently node32's two size classes\\nwork fine for growing, but the code should be simplified before extending\\nto other cases.)\\n>\\n> Within the size class, we just alloc a new node of lower size class\\n> and do memcpy(). I guess it will be almost same as what we do for\\n> growing.\\n\\nOh, the memcpy part is great, very simple. I mean the (compile-time) \\\"class\\ninfo\\\" table lookups are a bit awkward. I'm thinking the hard-coded numbers\\nlike this:\\n\\n.fanout = 3,\\n.inner_size = sizeof(RT_NODE_INNER_3) + 3 * sizeof(RT_PTR_ALLOC),\\n\\n...may be better with a #defined symbol that can also be used elsewhere.\\n\\n> I don't think\\n> shrinking class-3 to class-1 makes sense.\\n\\nAgreed. The smallest kind should just be freed when empty.\\n\\n> > Limited support for \\\"combined pointer-value slots\\\". At compile-time,\\nchoose either that or \\\"single-value leaves\\\" based on the size of the value\\ntype template parameter. Values that are pointer-sized or less can fit in\\nthe last-level child slots of nominal \\\"inner nodes\\\" without duplicated\\nleaf-node code. Node256 now must act like the previous 'node256 leaf',\\nsince zero is a valid value. Aside from that, this was a small change.\\n>\\n> Yes, but it also means that we use pointer-sized value anyway even if\\n> the value size is less than that, which wastes the memory, no?\\n\\nAt a low-level, that makes sense, but I've found an interesting global\\neffect showing the opposite: _less_ memory, which may compensate:\\n\\npsql -c \\\"select * from bench_search_random_nodes(1*1000*1000)\\\"\\nnum_keys = 992660\\n\\n(using a low enough number that the experimental change n125->n63 doesn't\\naffect anything)\\nheight = 4, n3 = 375258, n15 = 137490, n32 = 0, n63 = 0, n256 = 1025\\n\\nv31:\\n mem_allocated | load_ms | search_ms\\n---------------+---------+-----------\\n 47800768 | 253 | 134\\n\\n(unreleased code \\\"similar\\\" to v33, but among other things restores the\\nseparate \\\"extend down\\\" function)\\n mem_allocated | load_ms | search_ms\\n---------------+---------+-----------\\n 42926048 | 221 | 127\\n\\nI'd need to make sure, but apparently just going from 6 non-empty memory\\ncontexts to 3 (remember all values are embedded here) reduces memory\\nfragmentation significantly in this test. (That should also serve as a\\ndemonstration that additional size classes have both runtime costs as well\\nas benefits. We need to have a balance.)\\n\\nSo, I'm inclined to think the only reason to prefer \\\"multi-value leaves\\\" is\\nif 1) the value type is _bigger_ than a pointer 2) there is no convenient\\nabbreviation (like tid bitmaps have) and 3) the use case really needs to\\navoid another memory access. Under those circumstances, though, the new\\ncode plus lazy expansion etc might suit and be easier to maintain. That\\nsaid, I've mostly left alone the \\\"leaf\\\" types and functions, as well as\\nadded some detritus like \\\"const bool = false;\\\". It would look a *lot* nicer\\nif we gave up on multi-value leaves entirely, but there's no rush and I\\ndon't want to close that door entirely just yet.\\n\\n> > What I've shared here could work (in principal, since it uses uint64\\nvalues) for tidstore, possibly faster (untested) because of better code\\ndensity, but as mentioned I want to shoot for higher. For tidbitmap.c, I\\nwant to extend this idea and branch at run-time on a per-value basis, so\\nthat a page-table entry that fits in a pointer can go there, and if not,\\nit'll be a full leaf. (This technique enables more flexibility in\\nlossifying pages as well.) Run-time info will require e.g. an additional\\nbit per slot. Since the node header is now 3 bytes, we can spare one more\\nbyte in the node3 case. In addition, we can and should also bump it back up\\nto node4, still keeping the metadata within 8 bytes (no struct padding).\\n>\\n> Sounds good.\\n\\nThe additional bit per slot would require per-node logic and additional\\nbranches, which is not great. I'm now thinking a much easier way to get\\nthere is to give up (at least for now) on promising that \\\"run-time\\nembeddable values\\\" can use the full pointer-size (unlike value types found\\nembeddable at compile-time). Reserving the lowest pointer bit for a tag\\n\\\"value or pointer-to-leaf\\\" would have a much smaller code footprint. That\\nalso has a curious side-effect for TID offsets: They are one-based so\\nreserving the zero bit would actually simplify things: getting rid of the\\n+1/-1 logic when converting bits to/from offsets.\\n\\nIn addition, without a new bitmap, the smallest node can actually be up to\\na node5 with no struct padding, with a node2 as a subclass. (Those numbers\\ncoincidentally were also one scenario in the paper, when calculating\\nworst-case memory usage). That's worth considering.\\n\\n> > I've started in this patchset to refer to the node kinds as\\n\\\"4/16/48/256\\\", regardless of their actual fanout.\\n\\n> If we want to use the node kinds used in the paper, I think we should\\n> change the number in RT_NODE_KIND_X too.\\n\\nOh absolutely, this is nowhere near ready for cosmetic review :-)\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Jun 5, 2023 at 5:32 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> > Sometime in the not-too-distant future, I will start a new thread focusing on bitmap heap scan, but for now, I just want to share some progress on making the radix tree usable not only for that, but hopefully a wider range of applications, while making the code simpler and the binary smaller. The attached patches are incomplete (e.g. no iteration) and quite a bit messy, so tar'd and gzip'd for the curious (should apply on top of v32 0001-03 + 0007-09 ).> >>> Thank you for making progress on this. I agree with these directions> overall. I have some comments and questions:Glad to hear it and thanks for looking!> > * Other nodes will follow in due time, but only after I figure out how to do it nicely (ideas welcome!) -- currently node32's two size classes work fine for growing, but the code should be simplified before extending to other cases.)>> Within the size class, we just alloc a new node of lower size class> and do memcpy(). I guess it will be almost same as what we do for> growing.Oh, the memcpy part is great, very simple. I mean the (compile-time) \\\"class info\\\" table lookups are a bit awkward. I'm thinking the hard-coded numbers like this:.fanout = 3,.inner_size = sizeof(RT_NODE_INNER_3) + 3 * sizeof(RT_PTR_ALLOC),...may be better with a #defined symbol that can also be used elsewhere.> I don't think> shrinking class-3 to class-1 makes sense.Agreed. The smallest kind should just be freed when empty.> > Limited support for \\\"combined pointer-value slots\\\". At compile-time, choose either that or \\\"single-value leaves\\\" based on the size of the value type template parameter. Values that are pointer-sized or less can fit in the last-level child slots of nominal \\\"inner nodes\\\" without duplicated leaf-node code. Node256 now must act like the previous 'node256 leaf', since zero is a valid value. Aside from that, this was a small change.>> Yes, but it also means that we use pointer-sized value anyway even if> the value size is less than that, which wastes the memory, no?At a low-level, that makes sense, but I've found an interesting global effect showing the opposite: _less_ memory, which may compensate:psql -c \\\"select * from bench_search_random_nodes(1*1000*1000)\\\"num_keys = 992660(using a low enough number that the experimental change n125->n63 doesn't affect anything)height = 4, n3 = 375258, n15 = 137490, n32 = 0, n63 = 0, n256 = 1025v31: mem_allocated | load_ms | search_ms ---------------+---------+----------- 47800768 | 253 | 134(unreleased code \\\"similar\\\" to v33, but among other things restores the separate \\\"extend down\\\" function) mem_allocated | load_ms | search_ms ---------------+---------+----------- 42926048 | 221 | 127I'd need to make sure, but apparently just going from 6 non-empty memory contexts to 3 (remember all values are embedded here) reduces memory fragmentation significantly in this test. (That should also serve as a demonstration that additional size classes have both runtime costs as well as benefits. We need to have a balance.)So, I'm inclined to think the only reason to prefer \\\"multi-value leaves\\\" is if 1) the value type is _bigger_ than a pointer 2) there is no convenient abbreviation (like tid bitmaps have) and 3) the use case really needs to avoid another memory access. Under those circumstances, though, the new code plus lazy expansion etc might suit and be easier to maintain. That said, I've mostly left alone the \\\"leaf\\\" types and functions, as well as added some detritus like \\\"const bool = false;\\\". It would look a *lot* nicer if we gave up on multi-value leaves entirely, but there's no rush and I don't want to close that door entirely just yet.> > What I've shared here could work (in principal, since it uses uint64 values) for tidstore, possibly faster (untested) because of better code density, but as mentioned I want to shoot for higher. For tidbitmap.c, I want to extend this idea and branch at run-time on a per-value basis, so that a page-table entry that fits in a pointer can go there, and if not, it'll be a full leaf. (This technique enables more flexibility in lossifying pages as well.) Run-time info will require e.g. an additional bit per slot. Since the node header is now 3 bytes, we can spare one more byte in the node3 case. In addition, we can and should also bump it back up to node4, still keeping the metadata within 8 bytes (no struct padding).>> Sounds good.The additional bit per slot would require per-node logic and additional branches, which is not great. I'm now thinking a much easier way to get there is to give up (at least for now) on promising that \\\"run-time embeddable values\\\" can use the full pointer-size (unlike value types found embeddable at compile-time). Reserving the lowest pointer bit for a tag \\\"value or pointer-to-leaf\\\" would have a much smaller code footprint. That also has a curious side-effect for TID offsets: They are one-based so reserving the zero bit would actually simplify things: getting rid of the +1/-1 logic when converting bits to/from offsets.In addition, without a new bitmap, the smallest node can actually be up to a node5 with no struct padding, with a node2 as a subclass. (Those numbers coincidentally were also one scenario in the paper, when calculating worst-case memory usage). That's worth considering.> > I've started in this patchset to refer to the node kinds as \\\"4/16/48/256\\\", regardless of their actual fanout.> If we want to use the node kinds used in the paper, I think we should> change the number in RT_NODE_KIND_X too. Oh absolutely, this is nowhere near ready for cosmetic review :-) --John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 6 Jun 2023 12:13:36 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jun 6, 2023 at 2:13 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n>\\n> On Mon, Jun 5, 2023 at 5:32 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > Sometime in the not-too-distant future, I will start a new thread focusing on bitmap heap scan, but for now, I just want to share some progress on making the radix tree usable not only for that, but hopefully a wider range of applications, while making the code simpler and the binary smaller. The attached patches are incomplete (e.g. no iteration) and quite a bit messy, so tar'd and gzip'd for the curious (should apply on top of v32 0001-03 + 0007-09 ).\\n> > >\\n> >\\n> > Thank you for making progress on this. I agree with these directions\\n> > overall. I have some comments and questions:\\n>\\n> Glad to hear it and thanks for looking!\\n>\\n> > > * Other nodes will follow in due time, but only after I figure out how to do it nicely (ideas welcome!) -- currently node32's two size classes work fine for growing, but the code should be simplified before extending to other cases.)\\n> >\\n> > Within the size class, we just alloc a new node of lower size class\\n> > and do memcpy(). I guess it will be almost same as what we do for\\n> > growing.\\n>\\n> Oh, the memcpy part is great, very simple. I mean the (compile-time) \\\"class info\\\" table lookups are a bit awkward. I'm thinking the hard-coded numbers like this:\\n>\\n> .fanout = 3,\\n> .inner_size = sizeof(RT_NODE_INNER_3) + 3 * sizeof(RT_PTR_ALLOC),\\n>\\n> ...may be better with a #defined symbol that can also be used elsewhere.\\n\\nFWIW, exposing these definitions would be good in terms of testing too\\nsince we can use them in regression tests.\\n\\n>\\n> > I don't think\\n> > shrinking class-3 to class-1 makes sense.\\n>\\n> Agreed. The smallest kind should just be freed when empty.\\n>\\n> > > Limited support for \\\"combined pointer-value slots\\\". At compile-time, choose either that or \\\"single-value leaves\\\" based on the size of the value type template parameter. Values that are pointer-sized or less can fit in the last-level child slots of nominal \\\"inner nodes\\\" without duplicated leaf-node code. Node256 now must act like the previous 'node256 leaf', since zero is a valid value. Aside from that, this was a small change.\\n> >\\n> > Yes, but it also means that we use pointer-sized value anyway even if\\n> > the value size is less than that, which wastes the memory, no?\\n>\\n> At a low-level, that makes sense, but I've found an interesting global effect showing the opposite: _less_ memory, which may compensate:\\n>\\n> psql -c \\\"select * from bench_search_random_nodes(1*1000*1000)\\\"\\n> num_keys = 992660\\n>\\n> (using a low enough number that the experimental change n125->n63 doesn't affect anything)\\n> height = 4, n3 = 375258, n15 = 137490, n32 = 0, n63 = 0, n256 = 1025\\n>\\n> v31:\\n> mem_allocated | load_ms | search_ms\\n> ---------------+---------+-----------\\n> 47800768 | 253 | 134\\n>\\n> (unreleased code \\\"similar\\\" to v33, but among other things restores the separate \\\"extend down\\\" function)\\n> mem_allocated | load_ms | search_ms\\n> ---------------+---------+-----------\\n> 42926048 | 221 | 127\\n>\\n> I'd need to make sure, but apparently just going from 6 non-empty memory contexts to 3 (remember all values are embedded here) reduces memory fragmentation significantly in this test. (That should also serve as a demonstration that additional size classes have both runtime costs as well as benefits. We need to have a balance.)\\n\\nInteresting. The result would probably vary if we change the slab\\nblock sizes. I'd like to experiment if the code is available.\\n\\n>\\n> So, I'm inclined to think the only reason to prefer \\\"multi-value leaves\\\" is if 1) the value type is _bigger_ than a pointer 2) there is no convenient abbreviation (like tid bitmaps have) and 3) the use case really needs to avoid another memory access. Under those circumstances, though, the new code plus lazy expansion etc might suit and be easier to maintain.\\n\\nIndeed.\\n\\n>\\n> > > What I've shared here could work (in principal, since it uses uint64 values) for tidstore, possibly faster (untested) because of better code density, but as mentioned I want to shoot for higher. For tidbitmap.c, I want to extend this idea and branch at run-time on a per-value basis, so that a page-table entry that fits in a pointer can go there, and if not, it'll be a full leaf. (This technique enables more flexibility in lossifying pages as well.) Run-time info will require e.g. an additional bit per slot. Since the node header is now 3 bytes, we can spare one more byte in the node3 case. In addition, we can and should also bump it back up to node4, still keeping the metadata within 8 bytes (no struct padding).\\n> >\\n> > Sounds good.\\n>\\n> The additional bit per slot would require per-node logic and additional branches, which is not great. I'm now thinking a much easier way to get there is to give up (at least for now) on promising that \\\"run-time embeddable values\\\" can use the full pointer-size (unlike value types found embeddable at compile-time). Reserving the lowest pointer bit for a tag \\\"value or pointer-to-leaf\\\" would have a much smaller code footprint.\\n\\nDo you mean we can make sure that the value doesn't set the lowest\\nbit? Or is it an optimization for TIDStore?\\n\\n> In addition, without a new bitmap, the smallest node can actually be up to a node5 with no struct padding, with a node2 as a subclass. (Those numbers coincidentally were also one scenario in the paper, when calculating worst-case memory usage). That's worth considering.\\n\\nAgreed.\\n\\nFWIW please let me know if there are some experiments I can help with.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 13 Jun 2023 14:46:57 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jun 13, 2023 at 12:47 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> On Tue, Jun 6, 2023 at 2:13 PM John Naylor <john.naylor@enterprisedb.com>\\nwrote:\\n> >\\n\\n> > I'd need to make sure, but apparently just going from 6 non-empty\\nmemory contexts to 3 (remember all values are embedded here) reduces memory\\nfragmentation significantly in this test. (That should also serve as a\\ndemonstration that additional size classes have both runtime costs as well\\nas benefits. We need to have a balance.)\\n>\\n> Interesting. The result would probably vary if we change the slab\\n> block sizes. I'd like to experiment if the code is available.\\n\\nI cleaned up a few things and attached v34 so you can do that if you like.\\n(Note: what I said about node63/n125 not making a difference in that one\\ntest is not quite true since slab keeps a few empty blocks around. I did\\nsome rough mental math and I think it doesn't change the conclusion any.)\\n\\n0001-0007 is basically v33, but can apply on master.\\n\\n0008 just adds back RT_EXTEND_DOWN. I left it out to simplify moving to\\nrecursion.\\n\\n> > Oh, the memcpy part is great, very simple. I mean the (compile-time)\\n\\\"class info\\\" table lookups are a bit awkward. I'm thinking the hard-coded\\nnumbers like this:\\n> >\\n> > .fanout = 3,\\n> > .inner_size = sizeof(RT_NODE_INNER_3) + 3 * sizeof(RT_PTR_ALLOC),\\n> >\\n> > ...may be better with a #defined symbol that can also be used elsewhere.\\n>\\n> FWIW, exposing these definitions would be good in terms of testing too\\n> since we can use them in regression tests.\\n\\nI added some definitions in 0012. It kind of doesn't matter now what sizes\\nare the test unless it also can test that it stays within the expected\\nsize, if that makes sense. It is helpful during debugging to force growth\\nto stop at a certain size.\\n\\n> > > Within the size class, we just alloc a new node of lower size class\\n> > > and do memcpy().\\n\\nNot anymore. ;-) To be technical, it didn't \\\"just\\\" memcpy(), since it then\\nfell through to find the insert position and memmove(). In some parts of\\nAndres' prototype, no memmove() is necessary, because it memcpy()'s around\\nthe insert position, and puts the new child in the right place. I've done\\nthis in 0009.\\n\\nThe memcpy you mention was done for 1) simplicity 2) to avoid memset'ing.\\nWell, it was never necessary to memset the whole node in the first place.\\nOnly the header, slot index array, and isset arrays need to be zeroed, so\\nin 0011 we always do only that. That combines alloc and init functionality,\\nand it's simple everywhere.\\n\\nIn 0010 I restored iteration functionality -- it can no longer get the\\nshift from the node, because it's not there as of v33. I was not\\nparticularly impressed that there were no basic iteration tests, and in\\nfact the test_pattern test relied on functioning iteration. I added some\\nbasic tests. I'm not entirely pleased with testing overall, but I think\\nit's at least sufficient for the job. I had the idea to replace \\\"shift\\\"\\neverywhere and use \\\"level\\\" as a fundamental concept. This is clearer. I do\\nwant to make sure the compiler can compute the shift efficiently where\\nnecessary. I think that can wait until much later.\\n\\n0013 standardizes (mostly) on 4/16/48/256 for naming convention, regardless\\nof actual size, as I started to do earlier.\\n\\n0014 is part cleanup of shrinking, and part making grow-node-48 more\\nconsistent with the rest.\\n\\n> > The additional bit per slot would require per-node logic and additional\\nbranches, which is not great. I'm now thinking a much easier way to get\\nthere is to give up (at least for now) on promising that \\\"run-time\\nembeddable values\\\" can use the full pointer-size (unlike value types found\\nembeddable at compile-time). Reserving the lowest pointer bit for a tag\\n\\\"value or pointer-to-leaf\\\" would have a much smaller code footprint.\\n>\\n> Do you mean we can make sure that the value doesn't set the lowest\\n> bit? Or is it an optimization for TIDStore?\\n\\nIt will be up to the caller (the user of the template) -- if an\\nabbreviation is possible that fits in the upper 63 bits (with something to\\nguard for 32-bit platforms), the developer will be able to specify a\\nconversion function so that the caller only sees the full value when\\nsearching and setting. Without such a function, the template will fall back\\nto the size of the value type to determine how the value is stored.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 14 Jun 2023 13:23:07 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n> I cleaned up a few things and attached v34 so you can do that if you\\nlike.\\n\\nOf course, \\\"clean\\\" is a relative term. While making a small bit of progress\\nworking in tidbitmap.c earlier this week, I thought it useful to prototype\\nsome things in the tidstore, at which point I was reminded it no longer\\ncompiles because of my recent work. I put in the necessary incantations so\\nthat the v32 tidstore compiles and passes tests, so here's a patchset for\\nthat (but no vacuum changes). I thought it was a good time to also condense\\nit down to look more similar to previous patches, as a basis for future\\nwork.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Fri, 23 Jun 2023 16:54:21 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jun 23, 2023 at 6:54 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> I wrote:\\n> > I cleaned up a few things and attached v34 so you can do that if you like.\\n>\\n> Of course, \\\"clean\\\" is a relative term. While making a small bit of progress working in tidbitmap.c earlier this week, I thought it useful to prototype some things in the tidstore, at which point I was reminded it no longer compiles because of my recent work. I put in the necessary incantations so that the v32 tidstore compiles and passes tests, so here's a patchset for that (but no vacuum changes). I thought it was a good time to also condense it down to look more similar to previous patches, as a basis for future work.\\n>\\n\\nThank you for updating the patch set. I'll look at updates closely\\nearly next week.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 27 Jun 2023 17:20:03 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jun 27, 2023 at 5:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Jun 23, 2023 at 6:54 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> >\\n> >\\n> > I wrote:\\n> > > I cleaned up a few things and attached v34 so you can do that if you like.\\n> >\\n> > Of course, \\\"clean\\\" is a relative term. While making a small bit of progress working in tidbitmap.c earlier this week, I thought it useful to prototype some things in the tidstore, at which point I was reminded it no longer compiles because of my recent work. I put in the necessary incantations so that the v32 tidstore compiles and passes tests, so here's a patchset for that (but no vacuum changes). I thought it was a good time to also condense it down to look more similar to previous patches, as a basis for future work.\\n> >\\n>\\n> Thank you for updating the patch set. I'll look at updates closely\\n> early next week.\\n>\\n\\nI've run several benchmarks for v32, where before your recent change\\nstarting, and v35 patch. Overall the numbers are better than the\\nprevious version. Here is the test result where I used 1-byte value:\\n\\n\\\"select * from bench_load_random(10_000_000)\\\"\\n\\n* v35\\n radix tree leaves: 192 total in 0 blocks; 0 empty blocks; 0 free (0\\nchunks); 192 used\\n radix tree node 256: 13697472 total in 205 blocks; 0 empty blocks;\\n52400 free (25 chunks); 13645072 used\\n radix tree node 125: 86630592 total in 2115 blocks; 0 empty blocks;\\n7859376 free (6102 chunks); 78771216 used\\n radix tree node 32: 94912 total in 0 blocks; 10 empty blocks; 0 free\\n(0 chunks); 94912 used\\n radix tree node 15: 9269952 total in 1136 blocks; 0 empty blocks;\\n168 free (1 chunks); 9269784 used\\n radix tree node 3: 1915502784 total in 233826 blocks; 0 empty\\nblocks; 6560 free (164 chunks); 1915496224 used\\n mem_allocated | load_ms\\n---------------+---------\\n 2025194752 | 3011\\n(1 row)\\n\\n* v32\\n radix tree node 256: 192 total in 0 blocks; 0 empty blocks; 0 free\\n(0 chunks); 192 used\\n radix tree node 256: 13487552 total in 205 blocks; 0 empty blocks;\\n51600 free (25 chunks); 13435952 used\\n radix tree node 125: 192 total in 0 blocks; 0 empty blocks; 0 free\\n(0 chunks); 192 used\\n radix tree node 125: 86630592 total in 2115 blocks; 0 empty blocks;\\n7859376 free (6102 chunks); 78771216 used\\n radix tree node 32: 192 total in 0 blocks; 0 empty blocks; 0 free (0\\nchunks); 192 used\\n radix tree node 32: 94912 total in 0 blocks; 10 empty blocks; 0 free\\n(0 chunks); 94912 used\\n radix tree node 15: 192 total in 0 blocks; 0 empty blocks; 0 free (0\\nchunks); 192 used\\n radix tree node 15: 9269952 total in 1136 blocks; 0 empty blocks;\\n168 free (1 chunks); 9269784 used\\n radix tree node 3: 241597002 total in 29499 blocks; 0 empty blocks;\\n3864 free (161 chunks); 241593138 used\\n radix tree node 3: 1809039552 total in 221696 blocks; 0 empty\\nblocks; 5280 free (110 chunks); 1809034272 used\\n mem_allocated | load_ms\\n---------------+---------\\n 2160118410 | 3069\\n(1 row)\\n\\nAs you mentioned, the 1-byte value is embedded into 8 byte so 7 bytes\\nare unused, but we use less memory since we use less slab contexts and\\nsave fragmentations.\\n\\nI've also tested some large value cases (e.g. the value is 80-bytes)\\nand got a similar result.\\n\\nRegarding the codes, there are many todo and fixme comments so it\\nseems to me that your recent work is still in-progress. What is the\\ncurrent status? Can I start reviewing the code or should I wait for a\\nwhile until your recent work completes?\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 4 Jul 2023 14:48:39 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jul 4, 2023 at 12:49 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> As you mentioned, the 1-byte value is embedded into 8 byte so 7 bytes\\n> are unused, but we use less memory since we use less slab contexts and\\n> save fragmentations.\\n\\nThanks for testing. This tree is sparse enough that most of the space is\\ntaken up by small inner nodes, and not by leaves. So, it's encouraging to\\nsee a small space savings even here.\\n\\n> I've also tested some large value cases (e.g. the value is 80-bytes)\\n> and got a similar result.\\n\\nInteresting. With a separate allocation per value the overhead would be 8\\nbytes, or 10% here. It's plausible that savings elsewhere can hide that,\\nglobally.\\n\\n> Regarding the codes, there are many todo and fixme comments so it\\n> seems to me that your recent work is still in-progress. What is the\\n> current status? Can I start reviewing the code or should I wait for a\\n> while until your recent work completes?\\n\\nWell, it's going to be a bit of a mess until I can demonstrate it working\\n(and working well) with bitmap heap scan. Fixing that now is just going to\\ncreate conflicts. I do have a couple small older patches laying around that\\nwere quick experiments -- I think at least some of them should give a\\nperformance boost in loading speed, but haven't had time to test. Would you\\nlike to take a look?\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Tue, Jul 4, 2023 at 12:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> As you mentioned, the 1-byte value is embedded into 8 byte so 7 bytes> are unused, but we use less memory since we use less slab contexts and> save fragmentations.Thanks for testing. This tree is sparse enough that most of the space is taken up by small inner nodes, and not by leaves. So, it's encouraging to see a small space savings even here.> I've also tested some large value cases (e.g. the value is 80-bytes)> and got a similar result.Interesting. With a separate allocation per value the overhead would be 8 bytes, or 10% here. It's plausible that savings elsewhere can hide that, globally.> Regarding the codes, there are many todo and fixme comments so it> seems to me that your recent work is still in-progress. What is the> current status? Can I start reviewing the code or should I wait for a> while until your recent work completes?Well, it's going to be a bit of a mess until I can demonstrate it working (and working well) with bitmap heap scan. Fixing that now is just going to create conflicts. I do have a couple small older patches laying around that were quick experiments -- I think at least some of them should give a performance boost in loading speed, but haven't had time to test. Would you like to take a look?--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 5 Jul 2023 18:21:20 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jul 5, 2023 at 8:21 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n>\\n> On Tue, Jul 4, 2023 at 12:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > As you mentioned, the 1-byte value is embedded into 8 byte so 7 bytes\\n> > are unused, but we use less memory since we use less slab contexts and\\n> > save fragmentations.\\n>\\n> Thanks for testing. This tree is sparse enough that most of the space is taken up by small inner nodes, and not by leaves. So, it's encouraging to see a small space savings even here.\\n>\\n> > I've also tested some large value cases (e.g. the value is 80-bytes)\\n> > and got a similar result.\\n>\\n> Interesting. With a separate allocation per value the overhead would be 8 bytes, or 10% here. It's plausible that savings elsewhere can hide that, globally.\\n>\\n> > Regarding the codes, there are many todo and fixme comments so it\\n> > seems to me that your recent work is still in-progress. What is the\\n> > current status? Can I start reviewing the code or should I wait for a\\n> > while until your recent work completes?\\n>\\n> Well, it's going to be a bit of a mess until I can demonstrate it working (and working well) with bitmap heap scan. Fixing that now is just going to create conflicts. I do have a couple small older patches laying around that were quick experiments -- I think at least some of them should give a performance boost in loading speed, but haven't had time to test. Would you like to take a look?\\n\\nYes, I can experiment with these patches in the meantime.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 7 Jul 2023 16:18:40 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jul 7, 2023 at 2:19 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> On Wed, Jul 5, 2023 at 8:21 PM John Naylor <john.naylor@enterprisedb.com>\\nwrote:\\n> > Well, it's going to be a bit of a mess until I can demonstrate it\\nworking (and working well) with bitmap heap scan. Fixing that now is just\\ngoing to create conflicts. I do have a couple small older patches laying\\naround that were quick experiments -- I think at least some of them should\\ngive a performance boost in loading speed, but haven't had time to test.\\nWould you like to take a look?\\n>\\n> Yes, I can experiment with these patches in the meantime.\\n\\nOkay, here it is in v36. 0001-6 are same as v35.\\n\\n0007 removes a wasted extra computation newly introduced by refactoring\\ngrowing nodes. 0008 just makes 0011 nicer. Not worth testing by themselves,\\nbut better to be tidy.\\n0009 is an experiment to get rid of slow memmoves in node4, addressing a\\nlong-standing inefficiency. It looks a bit tricky, but I think it's\\nactually straightforward after drawing out the cases with pen and paper. It\\nworks if the fanout is either 4 or 5, so we have some wiggle room. This may\\ngive a noticeable boost if the input is reversed or random.\\n0010 allows RT_EXTEND_DOWN to reduce function calls, so should help with\\nsparse trees.\\n0011 reduces function calls when growing the smaller nodes. Not sure about\\nthis one -- possibly worth it for node4 only?\\n\\nIf these help, it'll show up more easily in smaller inputs. Large inputs\\ntend to be more dominated by RAM latency.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Sat, 8 Jul 2023 09:54:19 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sat, Jul 8, 2023 at 11:54 AM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> On Fri, Jul 7, 2023 at 2:19 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Wed, Jul 5, 2023 at 8:21 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n> > > Well, it's going to be a bit of a mess until I can demonstrate it working (and working well) with bitmap heap scan. Fixing that now is just going to create conflicts. I do have a couple small older patches laying around that were quick experiments -- I think at least some of them should give a performance boost in loading speed, but haven't had time to test. Would you like to take a look?\\n> >\\n> > Yes, I can experiment with these patches in the meantime.\\n>\\n> Okay, here it is in v36. 0001-6 are same as v35.\\n>\\n> 0007 removes a wasted extra computation newly introduced by refactoring growing nodes. 0008 just makes 0011 nicer. Not worth testing by themselves, but better to be tidy.\\n> 0009 is an experiment to get rid of slow memmoves in node4, addressing a long-standing inefficiency. It looks a bit tricky, but I think it's actually straightforward after drawing out the cases with pen and paper. It works if the fanout is either 4 or 5, so we have some wiggle room. This may give a noticeable boost if the input is reversed or random.\\n> 0010 allows RT_EXTEND_DOWN to reduce function calls, so should help with sparse trees.\\n> 0011 reduces function calls when growing the smaller nodes. Not sure about this one -- possibly worth it for node4 only?\\n>\\n> If these help, it'll show up more easily in smaller inputs. Large inputs tend to be more dominated by RAM latency.\\n\\nThanks for sharing the patches!\\n\\n0007, 0008, 0010, and 0011 are straightforward and agree to merge them.\\n\\nI have some questions on 0009 patch:\\n\\n+ /* shift chunks and children\\n+\\n+ Unfortunately, gcc has gotten too aggressive in\\nturning simple loops\\n+ into slow memmove's, so we have to be a bit more clever.\\n+ See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101481\\n+\\n+ We take advantage of the fact that a good\\n+ compiler can turn a memmove of a small constant power-of-two\\n+ number of bytes into a single load/store.\\n+ */\\n\\nAccording to the comment, this optimization is for only gcc? and there\\nis no negative impact when building with other compilers such as clang\\nby this change?\\n\\nI'm not sure that it's a good approach to hand-optimize the code much\\nto generate better instructions on gcc. I think this change reduces\\nreadability and maintainability. According to the bugzilla ticket\\nreferred to in the comment, it's realized as a bug in the community,\\nso once the gcc bug fixes, we might no longer need this trick, no?\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 13 Jul 2023 17:08:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Thu, Jul 13, 2023 at 5:08 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Sat, Jul 8, 2023 at 11:54 AM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> >\\n> >\\n> > On Fri, Jul 7, 2023 at 2:19 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Wed, Jul 5, 2023 at 8:21 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n> > > > Well, it's going to be a bit of a mess until I can demonstrate it working (and working well) with bitmap heap scan. Fixing that now is just going to create conflicts. I do have a couple small older patches laying around that were quick experiments -- I think at least some of them should give a performance boost in loading speed, but haven't had time to test. Would you like to take a look?\\n> > >\\n> > > Yes, I can experiment with these patches in the meantime.\\n> >\\n> > Okay, here it is in v36. 0001-6 are same as v35.\\n> >\\n> > 0007 removes a wasted extra computation newly introduced by refactoring growing nodes. 0008 just makes 0011 nicer. Not worth testing by themselves, but better to be tidy.\\n> > 0009 is an experiment to get rid of slow memmoves in node4, addressing a long-standing inefficiency. It looks a bit tricky, but I think it's actually straightforward after drawing out the cases with pen and paper. It works if the fanout is either 4 or 5, so we have some wiggle room. This may give a noticeable boost if the input is reversed or random.\\n> > 0010 allows RT_EXTEND_DOWN to reduce function calls, so should help with sparse trees.\\n> > 0011 reduces function calls when growing the smaller nodes. Not sure about this one -- possibly worth it for node4 only?\\n> >\\n> > If these help, it'll show up more easily in smaller inputs. Large inputs tend to be more dominated by RAM latency.\\n\\ncfbot reported some failures[1], and the v36 patch cannot be applied\\ncleanly to the current HEAD. I've attached updated patches to make\\ncfbot happy.\\n\\nRegards,\\n\\n[1] http://cfbot.cputube.org/highlights/all.html#3687\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 1 Aug 2023 17:12:05 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Jul 13, 2023 at 3:09 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> 0007, 0008, 0010, and 0011 are straightforward and agree to merge them.\\n\\n[Part 1 - clear the deck of earlier performance work etc]\\n\\nThanks for taking a look! I've merged 0007 and 0008. The others need a\\nperformance test to justify them -- an eyeball check is not enough. I've\\nnow made the time to do that.\\n\\n==== sparse loads\\n\\nv38 0001-0006 (still using node3 for this test only):\\n\\nselect avg(load_ms) from generate_series(1,100) x(x), lateral (select *\\nfrom bench_load_random_int(100 * 1000 * (1+x-x))) a;\\n avg\\n---------------------\\n 27.1000000000000000\\n\\nselect avg(load_ms) from generate_series(1,30) x(x), lateral (select * from\\nbench_load_random_int(500 * 1000 * (1+x-x))) a;\\n avg\\n----------------------\\n 165.6333333333333333\\n\\nv38-0007-Optimize-RT_EXTEND_DOWN.patch\\n\\nselect avg(load_ms) from generate_series(1,100) x(x), lateral (select *\\nfrom bench_load_random_int(100 * 1000 * (1+x-x))) a;\\n avg\\n---------------------\\n 25.0900000000000000\\n\\nselect avg(load_ms) from generate_series(1,30) x(x), lateral (select * from\\nbench_load_random_int(500 * 1000 * (1+x-x))) a;\\n avg\\n----------------------\\n 157.3666666666666667\\n\\nThat seems worth doing.\\n\\nv38-0008-Use-4-children-for-node-4-also-attempt-portable-.patch\\n\\nThis combines two things because I messed up a rebase: Use fanout of 4, and\\ntry some macros for shmem sizes, both 32- and 64-bit. Looking at this much,\\nI no longer have a goal to have a separate set of size-classes for non-SIMD\\nplatforms, because that would cause global maintenance problems -- it's\\nprobably better to reduce worst-case search time where necessary. That\\nwould be much more localized.\\n\\n> I have some questions on 0009 patch:\\n\\n> According to the comment, this optimization is for only gcc?\\n\\nNo, not at all. That tells me the comment is misleading.\\n\\n> I think this change reduces\\n> readability and maintainability.\\n\\nWell, that much is obvious. What is not obvious is how much it gains us\\nover the alternatives. I do have a simpler idea, though...\\n\\n==== load mostly node4\\n\\nselect * from bench_search_random_nodes(250*1000, '0xFFFFFF');\\nn4 = 42626, n16 = 21492, n32 = 0, n64 = 0, n256 = 257\\n mem_allocated | load_ms | search_ms\\n---------------+---------+-----------\\n 7352384 | 25 | 0\\n\\nv38-0009-TEMP-take-out-search-time-from-bench.patch\\n\\nThis is just to allow LATERAL queries for better measurements.\\n\\nselect avg(load_ms) from generate_series(1,100) x(x), lateral (select *\\nfrom bench_search_random_nodes(250*1000 * (1+x-x), '0xFFFFFF')) a;\\n\\n avg\\n---------------------\\n 24.8333333333333333\\n\\nv38-0010-Try-a-simpler-way-to-avoid-memmove.patch\\n\\nThis slightly rewrites the standard loop so that gcc doesn't turn it into a\\nmemmove(). Unlike the patch you didn't like, this *is* gcc-specific. (needs\\na comment, which I forgot)\\n\\n avg\\n---------------------\\n 21.9600000000000000\\n\\nSo, that's not a trivial difference. I wasn't a big fan of Andres'\\n__asm(\\\"\\\") workaround, but that may be just my ignorance about it. We need\\nsomething like either of the two.\\n\\nv38-0011-Optimize-add_child_4-take-2.patch\\n avg\\n---------------------\\n 21.3500000000000000\\n\\nThis is possibly faster than v38-0010, but looking like not worth the\\ncomplexity, assuming the other way avoids the bug going forward.\\n\\n> According to the bugzilla ticket\\n> referred to in the comment, it's realized as a bug in the community,\\n> so once the gcc bug fixes, we might no longer need this trick, no?\\n\\nNo comment in two years...\\n\\nv38-0013-Use-constant-for-initial-copy-of-chunks-and-chil.patch\\n\\nThis is the same as v37-0011. I wasn't quite satisfied with it since it\\nstill has two memcpy() calls, but it actually seems to regress:\\n\\n avg\\n---------------------\\n 22.0900000000000000\\n\\nv38-0012-Use-branch-free-coding-to-skip-new-element-index.patch\\n\\nThis patch uses a single loop for the copy.\\n\\n avg\\n---------------------\\n 21.0300000000000000\\n\\nWithin noise level of v38-0011, but it's small and simple, so I like it, at\\nleast for small arrays.\\n\\nv38-0014-node48-Remove-need-for-RIGHTMOST_ONE-in-radix-tr.patch\\nv38-0015-node48-Remove-dead-code-by-using-loop-local-var.patch\\n\\nJust small cleanups.\\n\\nv38-0016-Use-memcpy-for-children-when-growing-into-node48.patch\\n\\nMakes sense, but untested.\\n\\n===============\\n[Part 2]\\n\\nPer off-list discussion with Masahiko, it makes sense to take some of the\\nideas I've used locally on tidbitmap, and start incorporating them into\\nearlier vacuum work to get that out the door faster. With that in mind...\\n\\nv38-0017-Make-tidstore-more-similar-to-tidbitmap.patch\\n\\nThis uses a simplified PagetableEntry (unimaginatively called\\nBlocktableEntry just to avoid confusion), to be replaced with the real\\nthing at a later date. This is still fixed size, to be replaced with a\\nvarlen type.\\n\\nLooking at the tidstore tests again after some months, I'm not particularly\\npleased with the amount of code required for how little it seems to be\\ntesting, nor the output when something fails. (I wonder how hard it would\\nbe to have SQL functions that add blocks/offsets to the tid store, and emit\\ntuples of tids found in the store.)\\n\\nI'm also concerned about the number of places that have to know if the\\nstore is using shared memory or not. Something to think about later.\\n\\nv38-0018-Consolidate-inserting-updating-values.patch\\n\\nThis is something I coded up to get to an API more similar to one in\\nsimplehash, as used in tidbitmap.c. It seem worth doing on its own to\\nreduce code duplication, and also simplifies coding of varlen types and\\n\\\"runtime-embeddable values\\\".\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 14 Aug 2023 18:05:21 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn Mon, Aug 14, 2023 at 8:05 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> On Thu, Jul 13, 2023 at 3:09 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > 0007, 0008, 0010, and 0011 are straightforward and agree to merge them.\\n\\nThank you for updating the patch!\\n\\n>\\n> [Part 1 - clear the deck of earlier performance work etc]\\n>\\n> Thanks for taking a look! I've merged 0007 and 0008. The others need a performance test to justify them -- an eyeball check is not enough. I've now made the time to do that.\\n>\\n> ==== sparse loads\\n>\\n> v38 0001-0006 (still using node3 for this test only):\\n>\\n> select avg(load_ms) from generate_series(1,100) x(x), lateral (select * from bench_load_random_int(100 * 1000 * (1+x-x))) a;\\n> avg\\n> ---------------------\\n> 27.1000000000000000\\n>\\n> select avg(load_ms) from generate_series(1,30) x(x), lateral (select * from bench_load_random_int(500 * 1000 * (1+x-x))) a;\\n> avg\\n> ----------------------\\n> 165.6333333333333333\\n>\\n> v38-0007-Optimize-RT_EXTEND_DOWN.patch\\n>\\n> select avg(load_ms) from generate_series(1,100) x(x), lateral (select * from bench_load_random_int(100 * 1000 * (1+x-x))) a;\\n> avg\\n> ---------------------\\n> 25.0900000000000000\\n>\\n> select avg(load_ms) from generate_series(1,30) x(x), lateral (select * from bench_load_random_int(500 * 1000 * (1+x-x))) a;\\n> avg\\n> ----------------------\\n> 157.3666666666666667\\n>\\n> That seems worth doing.\\n>\\n> v38-0008-Use-4-children-for-node-4-also-attempt-portable-.patch\\n>\\n> This combines two things because I messed up a rebase: Use fanout of 4, and try some macros for shmem sizes, both 32- and 64-bit. Looking at this much, I no longer have a goal to have a separate set of size-classes for non-SIMD platforms, because that would cause global maintenance problems -- it's probably better to reduce worst-case search time where necessary. That would be much more localized.\\n>\\n> > I have some questions on 0009 patch:\\n>\\n> > According to the comment, this optimization is for only gcc?\\n>\\n> No, not at all. That tells me the comment is misleading.\\n>\\n> > I think this change reduces\\n> > readability and maintainability.\\n>\\n> Well, that much is obvious. What is not obvious is how much it gains us over the alternatives. I do have a simpler idea, though...\\n>\\n> ==== load mostly node4\\n>\\n> select * from bench_search_random_nodes(250*1000, '0xFFFFFF');\\n> n4 = 42626, n16 = 21492, n32 = 0, n64 = 0, n256 = 257\\n> mem_allocated | load_ms | search_ms\\n> ---------------+---------+-----------\\n> 7352384 | 25 | 0\\n>\\n> v38-0009-TEMP-take-out-search-time-from-bench.patch\\n>\\n> This is just to allow LATERAL queries for better measurements.\\n>\\n> select avg(load_ms) from generate_series(1,100) x(x), lateral (select * from bench_search_random_nodes(250*1000 * (1+x-x), '0xFFFFFF')) a;\\n>\\n> avg\\n> ---------------------\\n> 24.8333333333333333\\n\\n0007, 0008, and 0009 look good to me.\\n\\n>\\n> v38-0010-Try-a-simpler-way-to-avoid-memmove.patch\\n>\\n> This slightly rewrites the standard loop so that gcc doesn't turn it into a memmove(). Unlike the patch you didn't like, this *is* gcc-specific. (needs a comment, which I forgot)\\n>\\n> avg\\n> ---------------------\\n> 21.9600000000000000\\n>\\n> So, that's not a trivial difference. I wasn't a big fan of Andres' __asm(\\\"\\\") workaround, but that may be just my ignorance about it. We need something like either of the two.\\n>\\n> v38-0011-Optimize-add_child_4-take-2.patch\\n> avg\\n> ---------------------\\n> 21.3500000000000000\\n>\\n> This is possibly faster than v38-0010, but looking like not worth the complexity, assuming the other way avoids the bug going forward.\\n\\nI prefer 0010 but is it worth testing with other compilers such as clang?\\n\\n>\\n> > According to the bugzilla ticket\\n> > referred to in the comment, it's realized as a bug in the community,\\n> > so once the gcc bug fixes, we might no longer need this trick, no?\\n>\\n> No comment in two years...\\n>\\n> v38-0013-Use-constant-for-initial-copy-of-chunks-and-chil.patch\\n>\\n> This is the same as v37-0011. I wasn't quite satisfied with it since it still has two memcpy() calls, but it actually seems to regress:\\n>\\n> avg\\n> ---------------------\\n> 22.0900000000000000\\n>\\n> v38-0012-Use-branch-free-coding-to-skip-new-element-index.patch\\n>\\n> This patch uses a single loop for the copy.\\n>\\n> avg\\n> ---------------------\\n> 21.0300000000000000\\n>\\n> Within noise level of v38-0011, but it's small and simple, so I like it, at least for small arrays.\\n\\nAgreed.\\n\\n>\\n> v38-0014-node48-Remove-need-for-RIGHTMOST_ONE-in-radix-tr.patch\\n> v38-0015-node48-Remove-dead-code-by-using-loop-local-var.patch\\n>\\n> Just small cleanups.\\n>\\n> v38-0016-Use-memcpy-for-children-when-growing-into-node48.patch\\n>\\n> Makes sense, but untested.\\n\\nAgreed.\\n\\nBTW cfbot reported that some regression tests failed due to OOM. I've\\nattached the patch to fix it.\\n\\n>\\n> ===============\\n> [Part 2]\\n>\\n> Per off-list discussion with Masahiko, it makes sense to take some of the ideas I've used locally on tidbitmap, and start incorporating them into earlier vacuum work to get that out the door faster. With that in mind...\\n>\\n> v38-0017-Make-tidstore-more-similar-to-tidbitmap.patch\\n>\\n> This uses a simplified PagetableEntry (unimaginatively called BlocktableEntry just to avoid confusion), to be replaced with the real thing at a later date. This is still fixed size, to be replaced with a varlen type.\\n\\nThat's more readable.\\n\\n>\\n> Looking at the tidstore tests again after some months, I'm not particularly pleased with the amount of code required for how little it seems to be testing, nor the output when something fails. (I wonder how hard it would be to have SQL functions that add blocks/offsets to the tid store, and emit tuples of tids found in the store.)\\n\\nIt would not be hard to have such SQL functions. I'll try it.\\n\\n>\\n> I'm also concerned about the number of places that have to know if the store is using shared memory or not. Something to think about later.\\n>\\n> v38-0018-Consolidate-inserting-updating-values.patch\\n>\\n> This is something I coded up to get to an API more similar to one in simplehash, as used in tidbitmap.c. It seem worth doing on its own to reduce code duplication, and also simplifies coding of varlen types and \\\"runtime-embeddable values\\\".\\n\\nAgreed.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 15 Aug 2023 11:33:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Aug 15, 2023 at 9:34 AM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n\\n> BTW cfbot reported that some regression tests failed due to OOM. I've\\n> attached the patch to fix it.\\n\\nSeems worth doing now rather than later, so added this and squashed most of\\nthe rest together. I wonder if that test uses too much memory in general.\\nMaybe using the full uint64 is too much.\\n\\n> On Mon, Aug 14, 2023 at 8:05 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n\\n> > This is possibly faster than v38-0010, but looking like not worth the\\ncomplexity, assuming the other way avoids the bug going forward.\\n>\\n> I prefer 0010 but is it worth testing with other compilers such as clang?\\n\\nOkay, keeping 0010 with a comment, and leaving out 0011 for now. Clang is\\naggressive about unrolling loops, so may be worth looking globally at some\\npoint.\\n\\n> > v38-0012-Use-branch-free-coding-to-skip-new-element-index.patch\\n\\n> > Within noise level of v38-0011, but it's small and simple, so I like\\nit, at least for small arrays.\\n>\\n> Agreed.\\n\\nKeeping 0012 and not 0013.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Tue, 15 Aug 2023 18:53:05 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Aug 15, 2023 at 6:53 PM John Naylor <john.naylor@enterprisedb.com>\\nwrote:\\n>\\n> On Tue, Aug 15, 2023 at 9:34 AM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> > BTW cfbot reported that some regression tests failed due to OOM. I've\\n> > attached the patch to fix it.\\n>\\n> Seems worth doing now rather than later, so added this and squashed most\\nof the rest together.\\n\\nThis segfaults because of a mistake fixing a rebase conflict, so v40\\nattached.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 16 Aug 2023 18:04:34 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Aug 16, 2023 at 8:04 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> On Tue, Aug 15, 2023 at 6:53 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n> >\\n> > On Tue, Aug 15, 2023 at 9:34 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > BTW cfbot reported that some regression tests failed due to OOM. I've\\n> > > attached the patch to fix it.\\n> >\\n> > Seems worth doing now rather than later, so added this and squashed most of the rest together.\\n>\\n> This segfaults because of a mistake fixing a rebase conflict, so v40 attached.\\n>\\n\\nThank you for updating the patch set.\\n\\nOn Tue, Aug 15, 2023 at 11:33 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> On Mon, Aug 14, 2023 at 8:05 PM John Naylor\\n> <john.naylor@enterprisedb.com> wrote:\\n> > Looking at the tidstore tests again after some months, I'm not particularly pleased with the amount of code required for how little it seems to be testing, nor the output when something fails. (I wonder how hard it would be to have SQL functions that add blocks/offsets to the tid store, and emit tuples of tids found in the store.)\\n>\\n> It would not be hard to have such SQL functions. I'll try it.\\n\\nI've updated the regression tests for tidstore so that it uses SQL\\nfunctions to add blocks/offsets and dump its contents. The new test\\ncovers the same test coverages but it's executed using SQL functions\\ninstead of executing all tests in one SQL function.\\n\\n0008 patch fixes a bug in tidstore which I found during this work. We\\ndidn't recreate the radix tree in the same memory context when\\nTidStoreReset().\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Sun, 27 Aug 2023 21:53:00 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Aug 27, 2023 at 7:53 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> I've updated the regression tests for tidstore so that it uses SQL\\n> functions to add blocks/offsets and dump its contents. The new test\\n> covers the same test coverages but it's executed using SQL functions\\n> instead of executing all tests in one SQL function.\\n\\nThis is much nicer and more flexible, thanks! A few questions/comments:\\n\\ntidstore_dump_tids() returns a string -- is it difficult to turn this into\\na SRF, or is it just a bit more work?\\n\\nThe lookup test seems fine for now. The output would look nicer with an\\n\\\"order by tid\\\".\\n\\nI think we could have the SQL function tidstore_create() take a boolean for\\nshared memory. That would allow ad-hoc testing without a recompile, if I'm\\nnot mistaken.\\n\\n+SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])\\n+ FROM blocks, offsets\\n+ GROUP BY blk;\\n+ tidstore_set_block_offsets\\n+----------------------------\\n+\\n+\\n+\\n+\\n+\\n+(5 rows)\\n\\nCalling a void function multiple times leads to vertical whitespace, which\\nlooks a bit strange and may look better with some output, even if\\nirrelevant:\\n\\n-SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])\\n+SELECT row_number() over(order by blk), tidstore_set_block_offsets(blk,\\narray_agg(offsets.off)::int2[])\\n\\n row_number | tidstore_set_block_offsets\\n------------+----------------------------\\n 1 |\\n 2 |\\n 3 |\\n 4 |\\n 5 |\\n(5 rows)\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Sun, Aug 27, 2023 at 7:53 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> I've updated the regression tests for tidstore so that it uses SQL> functions to add blocks/offsets and dump its contents. The new test> covers the same test coverages but it's executed using SQL functions> instead of executing all tests in one SQL function.This is much nicer and more flexible, thanks! A few questions/comments:tidstore_dump_tids() returns a string -- is it difficult to turn this into a SRF, or is it just a bit more work?The lookup test seems fine for now. The output would look nicer with an \\\"order by tid\\\".I think we could have the SQL function tidstore_create() take a boolean for shared memory. That would allow ad-hoc testing without a recompile, if I'm not mistaken.+SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])+ FROM blocks, offsets+ GROUP BY blk;+ tidstore_set_block_offsets+----------------------------++++++(5 rows)Calling a void function multiple times leads to vertical whitespace, which looks a bit strange and may look better with some output, even if irrelevant:-SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])+SELECT row_number() over(order by blk), tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[]) row_number | tidstore_set_block_offsets------------+---------------------------- 1 | 2 | 3 | 4 | 5 |(5 rows)--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Mon, 28 Aug 2023 14:19:50 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Aug 28, 2023 at 4:20 PM John Naylor\\n<john.naylor@enterprisedb.com> wrote:\\n>\\n> On Sun, Aug 27, 2023 at 7:53 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I've updated the regression tests for tidstore so that it uses SQL\\n> > functions to add blocks/offsets and dump its contents. The new test\\n> > covers the same test coverages but it's executed using SQL functions\\n> > instead of executing all tests in one SQL function.\\n>\\n> This is much nicer and more flexible, thanks! A few questions/comments:\\n>\\n> tidstore_dump_tids() returns a string -- is it difficult to turn this into a SRF, or is it just a bit more work?\\n\\nIt's not difficult. I've changed it in v42 patch.\\n\\n>\\n> The lookup test seems fine for now. The output would look nicer with an \\\"order by tid\\\".\\n\\nAgreed.\\n\\n>\\n> I think we could have the SQL function tidstore_create() take a boolean for shared memory. That would allow ad-hoc testing without a recompile, if I'm not mistaken.\\n\\nAgreed.\\n\\n>\\n> +SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])\\n> + FROM blocks, offsets\\n> + GROUP BY blk;\\n> + tidstore_set_block_offsets\\n> +----------------------------\\n> +\\n> +\\n> +\\n> +\\n> +\\n> +(5 rows)\\n>\\n> Calling a void function multiple times leads to vertical whitespace, which looks a bit strange and may look better with some output, even if irrelevant:\\n>\\n> -SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])\\n> +SELECT row_number() over(order by blk), tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])\\n>\\n> row_number | tidstore_set_block_offsets\\n> ------------+----------------------------\\n> 1 |\\n> 2 |\\n> 3 |\\n> 4 |\\n> 5 |\\n> (5 rows)\\n\\nYes, it looks better.\\n\\nI've attached v42 patch set. I improved tidstore regression test codes\\nin addition of imcorporating the above comments.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 28 Aug 2023 23:43:22 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Aug 28, 2023 at 9:44 PM Masahiko Sawada <sawada.mshk@gmail.com>\\nwrote:\\n>\\n> I've attached v42 patch set. I improved tidstore regression test codes\\n> in addition of imcorporating the above comments.\\n\\nSeems fine at a glance, thanks. I will build on this to implement\\nvariable-length values. I have already finished one prerequisite which is:\\npublic APIs passing pointers to values.\\n\\n--\\nJohn Naylor\\nEDB: http://www.enterprisedb.com\\n\\nOn Mon, Aug 28, 2023 at 9:44 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:>> I've attached v42 patch set. I improved tidstore regression test codes> in addition of imcorporating the above comments.Seems fine at a glance, thanks. I will build on this to implement variable-length values. I have already finished one prerequisite which is: public APIs passing pointers to values.--John NaylorEDB: http://www.enterprisedb.com\",\n \"msg_date\": \"Wed, 6 Sep 2023 13:23:43 +0700\",\n \"msg_from\": \"John Naylor <john.naylor@enterprisedb.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Sep 6, 2023 at 3:23 PM John Naylor <john.naylor@enterprisedb.com> wrote:\\n>\\n>\\n> On Mon, Aug 28, 2023 at 9:44 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I've attached v42 patch set. I improved tidstore regression test codes\\n> > in addition of imcorporating the above comments.\\n>\\n> Seems fine at a glance, thanks. I will build on this to implement variable-length values.\\n\\nThanks.\\n\\n> I have already finished one prerequisite which is: public APIs passing pointers to values.\\n\\nGreat!\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Sep 2023 21:54:56 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-08-28 23:43:22 +0900, Masahiko Sawada wrote:\\n> I've attached v42 patch set. I improved tidstore regression test codes\\n> in addition of imcorporating the above comments.\\n\\nWhy did you need to disable the benchmark module for CI?\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Fri, 15 Sep 2023 17:03:12 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sat, Sep 16, 2023 at 9:03 AM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> Hi,\\n>\\n> On 2023-08-28 23:43:22 +0900, Masahiko Sawada wrote:\\n> > I've attached v42 patch set. I improved tidstore regression test codes\\n> > in addition of imcorporating the above comments.\\n>\\n> Why did you need to disable the benchmark module for CI?\\n\\nI didn't want to unnecessarily make cfbot unhappy since the benchmark\\nmodule is not going to get committed to the core and sometimes not\\nup-to-date.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Sun, 17 Sep 2023 12:21:47 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n\\n> Seems fine at a glance, thanks. I will build on this to implement variable-length values. I have already finished one prerequisite which is: public APIs passing pointers to values.\\n\\nSince my publishing schedule has not kept up, I'm just going to share\\nsomething similar to what I mentioned earlier, just to get things\\nmoving again.\\n\\n0001-0009 are from earlier versions, except for 0007 which makes a\\nbunch of superficial naming updates, similar to those done in a recent\\nother version. Somewhere along the way I fixed long-standing git\\nwhitespace warnings, but I don't remember if that's new here. In any\\ncase, let's try to preserve that.\\n\\n0010 is some minor refactoring to reduce duplication\\n\\n0011-0014 add public functions that give the caller more control over\\nthe input and responsibility for locking. They are not named well, but\\nI plan these to be temporary: They are currently used for the tidstore\\nonly, since that has much simpler tests than the standard radix tree\\ntests. One thing to note: since the tidstore has always done it's own\\nlocking within a larger structure, these patches don't bother to do\\nlocking at the radix tree level. Locking twice seems...not great.\\nThese patches are the main prerequisite for variable-length values.\\nOnce that is working well, we can switch the standard tests to the new\\nAPIs.\\n\\nNext steps include (some of these were briefly discussed off-list with\\nSawada-san):\\n\\n- template parameter for varlen values\\n- some callers to pass length in bytes\\n- block entries to have num_elems for # of bitmap words\\n- a way for updates to re-alloc values when needed\\n- aset allocation for values when appropriate\",\n \"msg_date\": \"Sat, 28 Oct 2023 15:56:42 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sat, Oct 28, 2023 at 5:56 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I wrote:\\n>\\n> > Seems fine at a glance, thanks. I will build on this to implement variable-length values. I have already finished one prerequisite which is: public APIs passing pointers to values.\\n>\\n> Since my publishing schedule has not kept up, I'm just going to share\\n> something similar to what I mentioned earlier, just to get things\\n> moving again.\\n\\nThanks for sharing the updates. I've returned to work today and will\\nresume working on this feature.\\n\\n>\\n> 0001-0009 are from earlier versions, except for 0007 which makes a\\n> bunch of superficial naming updates, similar to those done in a recent\\n> other version. Somewhere along the way I fixed long-standing git\\n> whitespace warnings, but I don't remember if that's new here. In any\\n> case, let's try to preserve that.\\n>\\n> 0010 is some minor refactoring to reduce duplication\\n>\\n> 0011-0014 add public functions that give the caller more control over\\n> the input and responsibility for locking. They are not named well, but\\n> I plan these to be temporary: They are currently used for the tidstore\\n> only, since that has much simpler tests than the standard radix tree\\n> tests. One thing to note: since the tidstore has always done it's own\\n> locking within a larger structure, these patches don't bother to do\\n> locking at the radix tree level. Locking twice seems...not great.\\n> These patches are the main prerequisite for variable-length values.\\n> Once that is working well, we can switch the standard tests to the new\\n> APIs.\\n\\nSince the variable-length values support is a big deal and would be\\nrelated to API design I'd like to discuss the API design first.\\nCurrently, we have the following APIs:\\n\\n---\\nRT_VALUE_TYPE\\nRT_GET(RT_RADIX_TREE *tree, uint64 key, bool *found);\\nor for variable-length value support,\\nRT_GET(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n\\nIf an entry already exists, return its pointer and set \\\"found\\\" to\\ntrue. Otherwize, insert an empty value with sz bytes, return its\\npointer, and set \\\"found\\\" to false.\\n\\n---\\nRT_VALUE_TYPE\\nRT_FIND(RT_RADIX_TREE *tree, uint64 key);\\n\\nIf an entry exists, return the pointer to the value, otherwise return NULL.\\n\\n(I omitted RT_SEARCH() as it's essentially the same as RT_FIND() and\\nwill probably get removed.)\\n\\n---\\nbool\\nRT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p);\\nor for variable-length value support,\\nRT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p, size_t sz);\\n\\nIf an entry already exists, update its value to 'value_p' and return\\ntrue. Otherwise set the value and return false.\\n\\nGiven variable-length value support, RT_GET() would have to do\\nrepalloc() if the existing value size is not big enough for the new\\nvalue, but it cannot as the radix tree doesn't know the size of each\\nstored value. Another idea is that the radix tree returns the pointer\\nto the slot and the caller updates the value accordingly. But it means\\nthat the caller has to update the slot properly while considering the\\nvalue size (embedded vs. single-leave value), which seems not a good\\nidea.\\n\\nTo deal with this problem, I think we can somewhat change RT_GET() API\\nas follow:\\n\\nRT_VALUE_TYPE\\nRT_INSERT(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n\\nIf the entry already exists, replace the value with a new empty value\\nwith sz bytes and set \\\"found\\\" to true. Otherwise, insert an empty\\nvalue, return its pointer, and set \\\"found\\\" to false.\\n\\nWe probably will find a better name but I use RT_INSERT() for\\ndiscussion. RT_INSERT() returns an empty slot regardless of existing\\nvalues. It can be used to insert a new value or to replace the value\\nwith a larger value.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 27 Nov 2023 15:45:18 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 27, 2023 at 1:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> Since the variable-length values support is a big deal and would be\\n> related to API design I'd like to discuss the API design first.\\n\\nThanks for the fine summary of the issues here.\\n\\n[Swapping this back in my head]\\n\\n> RT_VALUE_TYPE\\n> RT_GET(RT_RADIX_TREE *tree, uint64 key, bool *found);\\n> or for variable-length value support,\\n> RT_GET(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n>\\n> If an entry already exists, return its pointer and set \\\"found\\\" to\\n> true. Otherwize, insert an empty value with sz bytes, return its\\n> pointer, and set \\\"found\\\" to false.\\n\\n> ---\\n> bool\\n> RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p);\\n> or for variable-length value support,\\n> RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p, size_t sz);\\n>\\n> If an entry already exists, update its value to 'value_p' and return\\n> true. Otherwise set the value and return false.\\n\\nI'd have to double-check, but I think RT_SET is vestigial and I'm not\\nsure it has any advantage over RT_GET as I've sketched it out. I'm\\npretty sure it's only there now because changing the radix tree\\nregression tests is much harder than changing TID store.\\n\\n> Given variable-length value support, RT_GET() would have to do\\n> repalloc() if the existing value size is not big enough for the new\\n> value, but it cannot as the radix tree doesn't know the size of each\\n> stored value.\\n\\nI think we have two choices:\\n\\n- the value stores the \\\"length\\\". The caller would need to specify a\\nfunction to compute size from the \\\"length\\\" member. Note this assumes\\nthere is an array. I think both aspects are not great.\\n- the value stores the \\\"size\\\". Callers that store an array (as\\nPageTableEntry's do) would compute length when they need to. This\\nsounds easier.\\n\\n> Another idea is that the radix tree returns the pointer\\n> to the slot and the caller updates the value accordingly.\\n\\nI did exactly this in v43 TidStore if I understood you correctly. If I\\nmisunderstood you, can you clarify?\\n\\n> But it means\\n> that the caller has to update the slot properly while considering the\\n> value size (embedded vs. single-leave value), which seems not a good\\n> idea.\\n\\nFor this optimization, callers will have to know about pointer-sized\\nvalues and treat them differently, but they don't need to know the\\ndetails about how where they are stored.\\n\\nWhile we want to keep embedded values in the back of our minds, I\\nreally think the details should be postponed to a follow-up commit.\\n\\n> To deal with this problem, I think we can somewhat change RT_GET() API\\n> as follow:\\n>\\n> RT_VALUE_TYPE\\n> RT_INSERT(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n>\\n> If the entry already exists, replace the value with a new empty value\\n> with sz bytes and set \\\"found\\\" to true. Otherwise, insert an empty\\n> value, return its pointer, and set \\\"found\\\" to false.\\n>\\n> We probably will find a better name but I use RT_INSERT() for\\n> discussion. RT_INSERT() returns an empty slot regardless of existing\\n> values. It can be used to insert a new value or to replace the value\\n> with a larger value.\\n\\nFor the case we are discussing, bitmaps, updating an existing value is\\na bit tricky. We need the existing value to properly update it with\\nset or unset bits. This can't work in general without a lot of work\\nfor the caller.\\n\\nHowever, for vacuum, we have all values that we need up front. That\\ngives me an idea: Something like this insert API could be optimized\\nfor \\\"insert-only\\\": If we only free values when we free the whole tree\\nat the end, that's a clear use case for David Rowley's proposed \\\"bump\\ncontext\\\", which would save 8 bytes per allocation and be a bit faster.\\n[1] (RT_GET for varlen values would use an aset context, to allow\\nrepalloc, and nodes would continue to use slab).\\n\\n[1] https://www.postgresql.org/message-id/flat/CAApHDvqGSpCU95TmM=Bp=6xjL_nLys4zdZOpfNyWBk97Xrdj2w@mail.gmail.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 4 Dec 2023 15:21:16 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 4, 2023 at 5:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Nov 27, 2023 at 1:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > Since the variable-length values support is a big deal and would be\\n> > related to API design I'd like to discuss the API design first.\\n>\\n> Thanks for the fine summary of the issues here.\\n>\\n> [Swapping this back in my head]\\n>\\n> > RT_VALUE_TYPE\\n> > RT_GET(RT_RADIX_TREE *tree, uint64 key, bool *found);\\n> > or for variable-length value support,\\n> > RT_GET(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n> >\\n> > If an entry already exists, return its pointer and set \\\"found\\\" to\\n> > true. Otherwize, insert an empty value with sz bytes, return its\\n> > pointer, and set \\\"found\\\" to false.\\n>\\n> > ---\\n> > bool\\n> > RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p);\\n> > or for variable-length value support,\\n> > RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p, size_t sz);\\n> >\\n> > If an entry already exists, update its value to 'value_p' and return\\n> > true. Otherwise set the value and return false.\\n>\\n> I'd have to double-check, but I think RT_SET is vestigial and I'm not\\n> sure it has any advantage over RT_GET as I've sketched it out. I'm\\n> pretty sure it's only there now because changing the radix tree\\n> regression tests is much harder than changing TID store.\\n\\nAgreed.\\n\\n>\\n> > Given variable-length value support, RT_GET() would have to do\\n> > repalloc() if the existing value size is not big enough for the new\\n> > value, but it cannot as the radix tree doesn't know the size of each\\n> > stored value.\\n>\\n> I think we have two choices:\\n>\\n> - the value stores the \\\"length\\\". The caller would need to specify a\\n> function to compute size from the \\\"length\\\" member. Note this assumes\\n> there is an array. I think both aspects are not great.\\n> - the value stores the \\\"size\\\". Callers that store an array (as\\n> PageTableEntry's do) would compute length when they need to. This\\n> sounds easier.\\n\\nAs for the second idea, do we always need to require the value to have\\nthe \\\"size\\\" (e.g. int32) in the first field of its struct? If so, the\\ncaller will be able to use only 4 bytes in embedded value cases (or\\nwon't be able to use at all if the pointer size is 4 bytes).\\n\\n>\\n> > Another idea is that the radix tree returns the pointer\\n> > to the slot and the caller updates the value accordingly.\\n>\\n> I did exactly this in v43 TidStore if I understood you correctly. If I\\n> misunderstood you, can you clarify?\\n\\nI meant to expose RT_GET_SLOT_RECURSIVE() so that the caller updates\\nthe value as they want.\\n\\n>\\n> > But it means\\n> > that the caller has to update the slot properly while considering the\\n> > value size (embedded vs. single-leave value), which seems not a good\\n> > idea.\\n>\\n> For this optimization, callers will have to know about pointer-sized\\n> values and treat them differently, but they don't need to know the\\n> details about how where they are stored.\\n>\\n> While we want to keep embedded values in the back of our minds, I\\n> really think the details should be postponed to a follow-up commit.\\n\\nAgreed.\\n\\n>\\n> > To deal with this problem, I think we can somewhat change RT_GET() API\\n> > as follow:\\n> >\\n> > RT_VALUE_TYPE\\n> > RT_INSERT(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n> >\\n> > If the entry already exists, replace the value with a new empty value\\n> > with sz bytes and set \\\"found\\\" to true. Otherwise, insert an empty\\n> > value, return its pointer, and set \\\"found\\\" to false.\\n> >\\n> > We probably will find a better name but I use RT_INSERT() for\\n> > discussion. RT_INSERT() returns an empty slot regardless of existing\\n> > values. It can be used to insert a new value or to replace the value\\n> > with a larger value.\\n>\\n> For the case we are discussing, bitmaps, updating an existing value is\\n> a bit tricky. We need the existing value to properly update it with\\n> set or unset bits. This can't work in general without a lot of work\\n> for the caller.\\n\\nTrue.\\n\\n>\\n> However, for vacuum, we have all values that we need up front. That\\n> gives me an idea: Something like this insert API could be optimized\\n> for \\\"insert-only\\\": If we only free values when we free the whole tree\\n> at the end, that's a clear use case for David Rowley's proposed \\\"bump\\n> context\\\", which would save 8 bytes per allocation and be a bit faster.\\n> [1] (RT_GET for varlen values would use an aset context, to allow\\n> repalloc, and nodes would continue to use slab).\\n\\nInteresting idea and worth trying it. Do we need to protect the whole\\ntree as insert-only for safety? It's problematic if the user uses\\nmixed RT_INSERT() and RT_GET().\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Dec 2023 06:33:33 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 6, 2023 at 4:34 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Dec 4, 2023 at 5:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > > Given variable-length value support, RT_GET() would have to do\\n> > > repalloc() if the existing value size is not big enough for the new\\n> > > value, but it cannot as the radix tree doesn't know the size of each\\n> > > stored value.\\n> >\\n> > I think we have two choices:\\n> >\\n> > - the value stores the \\\"length\\\". The caller would need to specify a\\n> > function to compute size from the \\\"length\\\" member. Note this assumes\\n> > there is an array. I think both aspects are not great.\\n> > - the value stores the \\\"size\\\". Callers that store an array (as\\n> > PageTableEntry's do) would compute length when they need to. This\\n> > sounds easier.\\n>\\n> As for the second idea, do we always need to require the value to have\\n> the \\\"size\\\" (e.g. int32) in the first field of its struct? If so, the\\n> caller will be able to use only 4 bytes in embedded value cases (or\\n> won't be able to use at all if the pointer size is 4 bytes).\\n\\nWe could have an RT_SIZE_TYPE for varlen value types. That's easy.\\nThere is another way, though: (This is a digression into embedded\\nvalues, but it does illuminate some issues even aside from that)\\n\\nMy thinking a while ago was that an embedded value had no explicit\\nlength/size, but could be \\\"expanded\\\" into a conventional value for the\\ncaller. For bitmaps, the smallest full value would have length 1 and\\nwhatever size (For tid store maybe 16 bytes). This would happen\\nautomatically via a template function.\\n\\nNow I think that could be too complicated (especially for page table\\nentries, which have more bookkeeping than vacuum needs) and slow.\\nImagine this as an embedded value:\\n\\ntypedef struct BlocktableEntry\\n{\\n uint16 size;\\n\\n /* later: uint8 flags; for bitmap scan */\\n\\n /* 64 bit: 3 elements , 32-bit: 1 element */\\n OffsetNumber offsets[( sizeof(Pointer) - sizeof(int16) ) /\\nsizeof(OffsetNumber)];\\n\\n /* end of embeddable value */\\n\\n bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n} BlocktableEntry;\\n\\nHere we can use a slot to store up to 3 offsets, no matter how big\\nthey are. That's great because a bitmap could be mostly wasted space.\\nBut now the caller can't know up front how many bytes it needs until\\nit retrieves the value and sees what's already there. If there are\\nalready three values, the caller needs to tell the tree \\\"alloc this\\nmuch, update this slot you just gave me with the alloc (maybe DSA)\\npointer, and return the local pointer\\\". Then copy the 3 offsets into\\nset bits, and set whatever else it needs to. With normal values, same\\nthing, but with realloc.\\n\\nThis is a bit complex, but I see an advantage The tree doesn't need to\\ncare so much about the size, so the value doesn't need to contain the\\nsize. For our case, we can use length (number of bitmapwords) without\\nthe disadvantages I mentioned above, with length zero (or maybe -1)\\nmeaning \\\"no bitmapword array, the offsets are all in this small\\narray\\\".\\n\\n> > > Another idea is that the radix tree returns the pointer\\n> > > to the slot and the caller updates the value accordingly.\\n> >\\n> > I did exactly this in v43 TidStore if I understood you correctly. If I\\n> > misunderstood you, can you clarify?\\n>\\n> I meant to expose RT_GET_SLOT_RECURSIVE() so that the caller updates\\n> the value as they want.\\n\\nDid my sketch above get closer to that? Side note: I don't think we\\ncan expose that directly (e.g. need to check for create or extend\\nupwards), but some functionality can be a thin wrapper around it.\\n\\n> > However, for vacuum, we have all values that we need up front. That\\n> > gives me an idea: Something like this insert API could be optimized\\n> > for \\\"insert-only\\\": If we only free values when we free the whole tree\\n> > at the end, that's a clear use case for David Rowley's proposed \\\"bump\\n> > context\\\", which would save 8 bytes per allocation and be a bit faster.\\n> > [1] (RT_GET for varlen values would use an aset context, to allow\\n> > repalloc, and nodes would continue to use slab).\\n>\\n> Interesting idea and worth trying it. Do we need to protect the whole\\n> tree as insert-only for safety? It's problematic if the user uses\\n> mixed RT_INSERT() and RT_GET().\\n\\nYou're right, but I'm not sure what the policy should be.\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Dec 2023 13:39:21 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Nov 27, 2023 at 1:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Sat, Oct 28, 2023 at 5:56 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> bool\\n> RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p);\\n> or for variable-length value support,\\n> RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p, size_t sz);\\n>\\n> If an entry already exists, update its value to 'value_p' and return\\n> true. Otherwise set the value and return false.\\n\\n> RT_VALUE_TYPE\\n> RT_INSERT(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n>\\n> If the entry already exists, replace the value with a new empty value\\n> with sz bytes and set \\\"found\\\" to true. Otherwise, insert an empty\\n> value, return its pointer, and set \\\"found\\\" to false.\\n>\\n> We probably will find a better name but I use RT_INSERT() for\\n> discussion. RT_INSERT() returns an empty slot regardless of existing\\n> values. It can be used to insert a new value or to replace the value\\n> with a larger value.\\n\\nLooking at TidStoreSetBlockOffsets again (in particular how it works\\nwith RT_GET), and thinking about issues we've discussed, I think\\nRT_SET is sufficient for vacuum. Here's how it could work:\\n\\nTidStoreSetBlockOffsets could have a stack variable that's \\\"almost\\nalways\\\" large enough. When not, it can allocate in its own context. It\\nsets the necessary bits there. Then, it passes the pointer to RT_SET\\nwith the number of bytes to copy. That seems very simple.\\n\\nAt some future time, we can add a new function with the complex\\nbusiness about getting the current value to modify it, with the\\nre-alloc'ing that it might require.\\n\\nIn other words, from both an API perspective and a performance\\nperspective, it makes sense for tid store to have a simple \\\"set\\\"\\ninterface for vacuum that can be optimized for its characteristics\\n(insert only, ordered offsets). And also a more complex one for bitmap\\nscan (setting/unsetting bits of existing values, in any order). They\\ncan share the same iteration interface, key types, and value types.\\n\\nWhat do you think, Masahiko?\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Dec 2023 10:27:00 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 6, 2023 at 3:39 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Dec 6, 2023 at 4:34 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Dec 4, 2023 at 5:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > > Given variable-length value support, RT_GET() would have to do\\n> > > > repalloc() if the existing value size is not big enough for the new\\n> > > > value, but it cannot as the radix tree doesn't know the size of each\\n> > > > stored value.\\n> > >\\n> > > I think we have two choices:\\n> > >\\n> > > - the value stores the \\\"length\\\". The caller would need to specify a\\n> > > function to compute size from the \\\"length\\\" member. Note this assumes\\n> > > there is an array. I think both aspects are not great.\\n> > > - the value stores the \\\"size\\\". Callers that store an array (as\\n> > > PageTableEntry's do) would compute length when they need to. This\\n> > > sounds easier.\\n> >\\n> > As for the second idea, do we always need to require the value to have\\n> > the \\\"size\\\" (e.g. int32) in the first field of its struct? If so, the\\n> > caller will be able to use only 4 bytes in embedded value cases (or\\n> > won't be able to use at all if the pointer size is 4 bytes).\\n>\\n> We could have an RT_SIZE_TYPE for varlen value types. That's easy.\\n> There is another way, though: (This is a digression into embedded\\n> values, but it does illuminate some issues even aside from that)\\n>\\n> My thinking a while ago was that an embedded value had no explicit\\n> length/size, but could be \\\"expanded\\\" into a conventional value for the\\n> caller. For bitmaps, the smallest full value would have length 1 and\\n> whatever size (For tid store maybe 16 bytes). This would happen\\n> automatically via a template function.\\n>\\n> Now I think that could be too complicated (especially for page table\\n> entries, which have more bookkeeping than vacuum needs) and slow.\\n> Imagine this as an embedded value:\\n>\\n> typedef struct BlocktableEntry\\n> {\\n> uint16 size;\\n>\\n> /* later: uint8 flags; for bitmap scan */\\n>\\n> /* 64 bit: 3 elements , 32-bit: 1 element */\\n> OffsetNumber offsets[( sizeof(Pointer) - sizeof(int16) ) /\\n> sizeof(OffsetNumber)];\\n>\\n> /* end of embeddable value */\\n>\\n> bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n> } BlocktableEntry;\\n>\\n> Here we can use a slot to store up to 3 offsets, no matter how big\\n> they are. That's great because a bitmap could be mostly wasted space.\\n\\nInteresting idea.\\n\\n> But now the caller can't know up front how many bytes it needs until\\n> it retrieves the value and sees what's already there. If there are\\n> already three values, the caller needs to tell the tree \\\"alloc this\\n> much, update this slot you just gave me with the alloc (maybe DSA)\\n> pointer, and return the local pointer\\\". Then copy the 3 offsets into\\n> set bits, and set whatever else it needs to. With normal values, same\\n> thing, but with realloc.\\n>\\n> This is a bit complex, but I see an advantage The tree doesn't need to\\n> care so much about the size, so the value doesn't need to contain the\\n> size. For our case, we can use length (number of bitmapwords) without\\n> the disadvantages I mentioned above, with length zero (or maybe -1)\\n> meaning \\\"no bitmapword array, the offsets are all in this small\\n> array\\\".\\n\\nIt's still unclear to me why the value doesn't need to contain the size.\\n\\nIf I understand you correctly, in RT_GET(), the tree allocs a new\\nmemory and updates the slot where the value is embedded with the\\npointer to the allocated memory, and returns the pointer to the\\ncaller. Since the returned value, newly allocated memory, is still\\nempty, the callner needs to copy the contents of the old value to the\\nnew value and do whatever else it needs to.\\n\\nIf the value is already a single-leave value and RT_GET() is called\\nwith a larger size, the slot is always replaced with the newly\\nallocated area and the caller needs to copy the contents? If the tree\\ndoes realloc the value with a new size, how does the tree know the new\\nvalue is larger than the existing value? It seems like the caller\\nneeds to provide a function to calculate the size of the value based\\non the length.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 10:56:50 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 7, 2023 at 12:27 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Nov 27, 2023 at 1:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Sat, Oct 28, 2023 at 5:56 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > bool\\n> > RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p);\\n> > or for variable-length value support,\\n> > RT_SET(RT_RADIX_TREE *tree, uint64 key, RT_VALUE_TYPE *value_p, size_t sz);\\n> >\\n> > If an entry already exists, update its value to 'value_p' and return\\n> > true. Otherwise set the value and return false.\\n>\\n> > RT_VALUE_TYPE\\n> > RT_INSERT(RT_RADIX_TREE *tree, uint64 key, size_t sz, bool *found);\\n> >\\n> > If the entry already exists, replace the value with a new empty value\\n> > with sz bytes and set \\\"found\\\" to true. Otherwise, insert an empty\\n> > value, return its pointer, and set \\\"found\\\" to false.\\n> >\\n> > We probably will find a better name but I use RT_INSERT() for\\n> > discussion. RT_INSERT() returns an empty slot regardless of existing\\n> > values. It can be used to insert a new value or to replace the value\\n> > with a larger value.\\n>\\n> Looking at TidStoreSetBlockOffsets again (in particular how it works\\n> with RT_GET), and thinking about issues we've discussed, I think\\n> RT_SET is sufficient for vacuum. Here's how it could work:\\n>\\n> TidStoreSetBlockOffsets could have a stack variable that's \\\"almost\\n> always\\\" large enough. When not, it can allocate in its own context. It\\n> sets the necessary bits there. Then, it passes the pointer to RT_SET\\n> with the number of bytes to copy. That seems very simple.\\n\\nRight.\\n\\n>\\n> At some future time, we can add a new function with the complex\\n> business about getting the current value to modify it, with the\\n> re-alloc'ing that it might require.\\n>\\n> In other words, from both an API perspective and a performance\\n> perspective, it makes sense for tid store to have a simple \\\"set\\\"\\n> interface for vacuum that can be optimized for its characteristics\\n> (insert only, ordered offsets). And also a more complex one for bitmap\\n> scan (setting/unsetting bits of existing values, in any order). They\\n> can share the same iteration interface, key types, and value types.\\n>\\n> What do you think, Masahiko?\\n\\nGood point. RT_SET() would be faster than RT_GET() and updating the\\nvalue because RT_SET() would not need to take care of the existing\\nvalue (its size, embedded or not, realloc etc).\\n\\nI think that we can separate the radix tree patch into two parts: the\\nmain implementation with RT_SET(), and more complex APIs such as\\nRT_GET() etc. That way, it would probably make it easy to complete the\\nradix tree and tidstore first.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 11:24:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 8:57 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> It's still unclear to me why the value doesn't need to contain the size.\\n>\\n> If I understand you correctly, in RT_GET(), the tree allocs a new\\n> memory and updates the slot where the value is embedded with the\\n> pointer to the allocated memory, and returns the pointer to the\\n> caller. Since the returned value, newly allocated memory, is still\\n> empty, the callner needs to copy the contents of the old value to the\\n> new value and do whatever else it needs to.\\n>\\n> If the value is already a single-leave value and RT_GET() is called\\n> with a larger size, the slot is always replaced with the newly\\n> allocated area and the caller needs to copy the contents? If the tree\\n> does realloc the value with a new size, how does the tree know the new\\n> value is larger than the existing value? It seems like the caller\\n> needs to provide a function to calculate the size of the value based\\n> on the length.\\n\\nRight. My brief description mentioned one thing without details: The\\ncaller would need to control whether to re-alloc. RT_GET would pass\\nthe size. If nothing is found, the tree would allocate. If there is a\\nvalue already, just return it. That means both the address of the\\nslot, and the local pointer to the value (with embedded, would be the\\nsame address). The caller checks if the array is long enough. If not,\\ncall a new function that takes the new size, the address of the slot,\\nand the pointer to the old value. The tree would re-alloc, put the\\nalloc pointer in the slot and return the new local pointer. But as we\\nagreed, that is all follow-up work.\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 11:37:17 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 1:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Dec 8, 2023 at 8:57 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > It's still unclear to me why the value doesn't need to contain the size.\\n> >\\n> > If I understand you correctly, in RT_GET(), the tree allocs a new\\n> > memory and updates the slot where the value is embedded with the\\n> > pointer to the allocated memory, and returns the pointer to the\\n> > caller. Since the returned value, newly allocated memory, is still\\n> > empty, the callner needs to copy the contents of the old value to the\\n> > new value and do whatever else it needs to.\\n> >\\n> > If the value is already a single-leave value and RT_GET() is called\\n> > with a larger size, the slot is always replaced with the newly\\n> > allocated area and the caller needs to copy the contents? If the tree\\n> > does realloc the value with a new size, how does the tree know the new\\n> > value is larger than the existing value? It seems like the caller\\n> > needs to provide a function to calculate the size of the value based\\n> > on the length.\\n>\\n> Right. My brief description mentioned one thing without details: The\\n> caller would need to control whether to re-alloc. RT_GET would pass\\n> the size. If nothing is found, the tree would allocate. If there is a\\n> value already, just return it. That means both the address of the\\n> slot, and the local pointer to the value (with embedded, would be the\\n> same address). The caller checks if the array is long enough. If not,\\n> call a new function that takes the new size, the address of the slot,\\n> and the pointer to the old value. The tree would re-alloc, put the\\n> alloc pointer in the slot and return the new local pointer. But as we\\n> agreed, that is all follow-up work.\\n\\nThank you for the detailed explanation. That makes sense to me. We\\nwill address it as a follow-up work.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 15:45:12 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 3:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Dec 8, 2023 at 1:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Fri, Dec 8, 2023 at 8:57 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > It's still unclear to me why the value doesn't need to contain the size.\\n> > >\\n> > > If I understand you correctly, in RT_GET(), the tree allocs a new\\n> > > memory and updates the slot where the value is embedded with the\\n> > > pointer to the allocated memory, and returns the pointer to the\\n> > > caller. Since the returned value, newly allocated memory, is still\\n> > > empty, the callner needs to copy the contents of the old value to the\\n> > > new value and do whatever else it needs to.\\n> > >\\n> > > If the value is already a single-leave value and RT_GET() is called\\n> > > with a larger size, the slot is always replaced with the newly\\n> > > allocated area and the caller needs to copy the contents? If the tree\\n> > > does realloc the value with a new size, how does the tree know the new\\n> > > value is larger than the existing value? It seems like the caller\\n> > > needs to provide a function to calculate the size of the value based\\n> > > on the length.\\n> >\\n> > Right. My brief description mentioned one thing without details: The\\n> > caller would need to control whether to re-alloc. RT_GET would pass\\n> > the size. If nothing is found, the tree would allocate. If there is a\\n> > value already, just return it. That means both the address of the\\n> > slot, and the local pointer to the value (with embedded, would be the\\n> > same address).\\n\\nBTW Given that the actual value size can be calculated only by the\\ncaller, how does the tree know if the value is embedded or not? It's\\nprobably related to how to store combined pointer/value slots. If leaf\\nnodes have a bitmap array that indicates the corresponding slot is an\\nembedded value or a pointer to a value, it would be easy. But since\\nthe bitmap array is needed only in the leaf nodes, internal nodes and\\nleaf nodes will no longer be identical structure, which is not a bad\\nthing to me, though.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 17:05:53 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 3:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> BTW Given that the actual value size can be calculated only by the\\n> caller, how does the tree know if the value is embedded or not? It's\\n> probably related to how to store combined pointer/value slots.\\n\\nRight, this is future work. At first, variable-length types will have\\nto be single-value leaves. In fact, the idea for storing up to 3\\noffsets in the bitmap header could be done this way -- it would just\\nbe a (small) single-value leaf.\\n\\n(Reminder: Currently, fixed-length values are compile-time embeddable\\nif the platform pointer size is big enough.)\\n\\n> If leaf\\n> nodes have a bitmap array that indicates the corresponding slot is an\\n> embedded value or a pointer to a value, it would be easy.\\n\\nThat's the most general way to do it. We could do it much more easily\\nwith a pointer tag, although for the above idea it may require some\\nendian-aware coding. Both were mentioned in the paper, I recall.\\n\\n> But since\\n> the bitmap array is needed only in the leaf nodes, internal nodes and\\n> leaf nodes will no longer be identical structure, which is not a bad\\n> thing to me, though.\\n\\nAbsolutely no way we are going back to double everything: double\\ntypes, double functions, double memory contexts. Plus, that bitmap in\\ninner nodes could indicate a pointer to a leaf that got there by \\\"lazy\\nexpansion\\\".\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 17:46:29 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 7:46 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Dec 8, 2023 at 3:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > BTW Given that the actual value size can be calculated only by the\\n> > caller, how does the tree know if the value is embedded or not? It's\\n> > probably related to how to store combined pointer/value slots.\\n>\\n> Right, this is future work. At first, variable-length types will have\\n> to be single-value leaves. In fact, the idea for storing up to 3\\n> offsets in the bitmap header could be done this way -- it would just\\n> be a (small) single-value leaf.\\n\\nAgreed.\\n\\n>\\n> (Reminder: Currently, fixed-length values are compile-time embeddable\\n> if the platform pointer size is big enough.)\\n>\\n> > If leaf\\n> > nodes have a bitmap array that indicates the corresponding slot is an\\n> > embedded value or a pointer to a value, it would be easy.\\n>\\n> That's the most general way to do it. We could do it much more easily\\n> with a pointer tag, although for the above idea it may require some\\n> endian-aware coding. Both were mentioned in the paper, I recall.\\n\\nTrue. Probably we can use the combined pointer/value slots approach\\nonly if the tree is able to use the pointer tagging. That is, if the\\ncaller allows the tree to use one bit of the value.\\n\\nI'm going to update the patch based on the recent discussion (RT_SET()\\nand variable-length values) etc., and post the patch set early next\\nweek.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Dec 2023 21:44:12 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 8, 2023 at 9:44 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Dec 8, 2023 at 7:46 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Fri, Dec 8, 2023 at 3:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > BTW Given that the actual value size can be calculated only by the\\n> > > caller, how does the tree know if the value is embedded or not? It's\\n> > > probably related to how to store combined pointer/value slots.\\n> >\\n> > Right, this is future work. At first, variable-length types will have\\n> > to be single-value leaves. In fact, the idea for storing up to 3\\n> > offsets in the bitmap header could be done this way -- it would just\\n> > be a (small) single-value leaf.\\n>\\n> Agreed.\\n>\\n> >\\n> > (Reminder: Currently, fixed-length values are compile-time embeddable\\n> > if the platform pointer size is big enough.)\\n> >\\n> > > If leaf\\n> > > nodes have a bitmap array that indicates the corresponding slot is an\\n> > > embedded value or a pointer to a value, it would be easy.\\n> >\\n> > That's the most general way to do it. We could do it much more easily\\n> > with a pointer tag, although for the above idea it may require some\\n> > endian-aware coding. Both were mentioned in the paper, I recall.\\n>\\n> True. Probably we can use the combined pointer/value slots approach\\n> only if the tree is able to use the pointer tagging. That is, if the\\n> caller allows the tree to use one bit of the value.\\n>\\n> I'm going to update the patch based on the recent discussion (RT_SET()\\n> and variable-length values) etc., and post the patch set early next\\n> week.\\n\\nI've attached the updated patch set. From the previous patch set, I've\\nmerged patches 0007 to 0010. The other changes such as adding RT_GET()\\nstill are unmerged for now, for discussion. Probably we can make them\\nas follow-up patches as we discussed. 0011 to 0015 patches are new\\nchanges for v44 patch set, which removes RT_SEARCH() and RT_SET() and\\nsupport variable-length values.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 11 Dec 2023 15:17:37 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 11, 2023 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> I've attached the updated patch set. From the previous patch set, I've\\n> merged patches 0007 to 0010. The other changes such as adding RT_GET()\\n> still are unmerged for now, for discussion. Probably we can make them\\n> as follow-up patches as we discussed. 0011 to 0015 patches are new\\n> changes for v44 patch set, which removes RT_SEARCH() and RT_SET() and\\n> support variable-length values.\\n\\nThis looks like the right direction, and I'm pleased it's not much\\nadditional code on top of my last patch.\\n\\nv44-0014:\\n\\n+#ifdef RT_VARLEN_VALUE\\n+ /* XXX: need to choose block sizes? */\\n+ tree->leaf_ctx = AllocSetContextCreate(ctx,\\n+ \\\"radix tree leaves\\\",\\n+ ALLOCSET_DEFAULT_SIZES);\\n+#else\\n+ tree->leaf_ctx = SlabContextCreate(ctx,\\n+ \\\"radix tree leaves\\\",\\n+ RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n+ sizeof(RT_VALUE_TYPE));\\n+#endif /* RT_VARLEN_VALUE */\\n\\nChoosing block size: Similar to what we've discussed previously around\\nDSA segments, we might model this on CreateWorkExprContext() in\\nsrc/backend/executor/execUtils.c. Maybe tid store can pass maint_w_m /\\nautovac_w_m (later work_mem for bitmap scan). RT_CREATE could set the\\nmax block size to 1/16 of that, or less.\\n\\nAlso, it occurred to me that compile-time embeddable values don't need\\na leaf context. I'm not sure how many places assume that there is\\nalways a leaf context. If not many, it may be worth not creating one\\nhere, just to be tidy.\\n\\n+ size_t copysize;\\n\\n- memcpy(leaf.local, value_p, sizeof(RT_VALUE_TYPE));\\n+ copysize = sizeof(RT_VALUE_TYPE);\\n+#endif\\n+\\n+ memcpy(leaf.local, value_p, copysize);\\n\\nI'm not sure this indirection adds clarity. I guess the intent was to\\nkeep from saying \\\"memcpy\\\" twice, but now the code has to say \\\"copysize\\n= foo\\\" twice.\\n\\nFor varlen case, we need to watch out for slowness because of memcpy.\\nLet's put that off for later testing, though. We may someday want to\\navoid a memcpy call for the varlen case, so let's keep it flexible\\nhere.\\n\\nv44-0015:\\n\\n+#define SizeOfBlocktableEntry (offsetof(\\n\\nUnused.\\n\\n+ char buf[MaxBlocktableEntrySize] = {0};\\n\\nZeroing this buffer is probably going to be expensive. Also see this\\npre-existing comment:\\n/* WIP: slow, since it writes to memory for every bit */\\npage->words[wordnum] |= ((bitmapword) 1 << bitnum);\\n\\nFor this function (which will be vacuum-only, so we can assume\\nordering), in the loop we can:\\n* declare the local bitmapword variable to be zero\\n* set the bits on it\\n* write it out to the right location when done.\\n\\nLet's fix both of these at once.\\n\\n+ if (TidStoreIsShared(ts))\\n+ shared_rt_set(ts->tree.shared, blkno, (void *) page, page_len);\\n+ else\\n+ local_rt_set(ts->tree.local, blkno, (void *) page, page_len);\\n\\nIs there a reason for \\\"void *\\\"? The declared parameter is\\n\\\"RT_VALUE_TYPE *value_p\\\" in 0014.\\nAlso, since this function is for vacuum (and other uses will need a\\nnew function), let's assert the returned bool is false.\\n\\nDoes iteration still work? If so, it's not too early to re-wire this\\nup with vacuum and see how it behaves.\\n\\nLastly, my compiler has a warning that CI doesn't have:\\n\\nIn file included from ../src/test/modules/test_radixtree/test_radixtree.c:121:\\n../src/include/lib/radixtree.h: In function ‘rt_find.isra’:\\n../src/include/lib/radixtree.h:2142:24: warning: ‘slot’ may be used\\nuninitialized [-Wmaybe-uninitialized]\\n 2142 | return (RT_VALUE_TYPE*) slot;\\n | ^~~~~~~~~~~~~~~~~~~~~\\n../src/include/lib/radixtree.h:2112:23: note: ‘slot’ was declared here\\n 2112 | RT_PTR_ALLOC *slot;\\n | ^~~~\\n\\n\\n\",\n \"msg_date\": \"Tue, 12 Dec 2023 09:53:08 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 12, 2023 at 11:53 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Dec 11, 2023 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > I've attached the updated patch set. From the previous patch set, I've\\n> > merged patches 0007 to 0010. The other changes such as adding RT_GET()\\n> > still are unmerged for now, for discussion. Probably we can make them\\n> > as follow-up patches as we discussed. 0011 to 0015 patches are new\\n> > changes for v44 patch set, which removes RT_SEARCH() and RT_SET() and\\n> > support variable-length values.\\n>\\n> This looks like the right direction, and I'm pleased it's not much\\n> additional code on top of my last patch.\\n>\\n> v44-0014:\\n>\\n> +#ifdef RT_VARLEN_VALUE\\n> + /* XXX: need to choose block sizes? */\\n> + tree->leaf_ctx = AllocSetContextCreate(ctx,\\n> + \\\"radix tree leaves\\\",\\n> + ALLOCSET_DEFAULT_SIZES);\\n> +#else\\n> + tree->leaf_ctx = SlabContextCreate(ctx,\\n> + \\\"radix tree leaves\\\",\\n> + RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> + sizeof(RT_VALUE_TYPE));\\n> +#endif /* RT_VARLEN_VALUE */\\n>\\n> Choosing block size: Similar to what we've discussed previously around\\n> DSA segments, we might model this on CreateWorkExprContext() in\\n> src/backend/executor/execUtils.c. Maybe tid store can pass maint_w_m /\\n> autovac_w_m (later work_mem for bitmap scan). RT_CREATE could set the\\n> max block size to 1/16 of that, or less.\\n>\\n> Also, it occurred to me that compile-time embeddable values don't need\\n> a leaf context. I'm not sure how many places assume that there is\\n> always a leaf context. If not many, it may be worth not creating one\\n> here, just to be tidy.\\n>\\n> + size_t copysize;\\n>\\n> - memcpy(leaf.local, value_p, sizeof(RT_VALUE_TYPE));\\n> + copysize = sizeof(RT_VALUE_TYPE);\\n> +#endif\\n> +\\n> + memcpy(leaf.local, value_p, copysize);\\n>\\n> I'm not sure this indirection adds clarity. I guess the intent was to\\n> keep from saying \\\"memcpy\\\" twice, but now the code has to say \\\"copysize\\n> = foo\\\" twice.\\n>\\n> For varlen case, we need to watch out for slowness because of memcpy.\\n> Let's put that off for later testing, though. We may someday want to\\n> avoid a memcpy call for the varlen case, so let's keep it flexible\\n> here.\\n>\\n> v44-0015:\\n>\\n> +#define SizeOfBlocktableEntry (offsetof(\\n>\\n> Unused.\\n>\\n> + char buf[MaxBlocktableEntrySize] = {0};\\n>\\n> Zeroing this buffer is probably going to be expensive. Also see this\\n> pre-existing comment:\\n> /* WIP: slow, since it writes to memory for every bit */\\n> page->words[wordnum] |= ((bitmapword) 1 << bitnum);\\n>\\n> For this function (which will be vacuum-only, so we can assume\\n> ordering), in the loop we can:\\n> * declare the local bitmapword variable to be zero\\n> * set the bits on it\\n> * write it out to the right location when done.\\n>\\n> Let's fix both of these at once.\\n>\\n> + if (TidStoreIsShared(ts))\\n> + shared_rt_set(ts->tree.shared, blkno, (void *) page, page_len);\\n> + else\\n> + local_rt_set(ts->tree.local, blkno, (void *) page, page_len);\\n>\\n> Is there a reason for \\\"void *\\\"? The declared parameter is\\n> \\\"RT_VALUE_TYPE *value_p\\\" in 0014.\\n> Also, since this function is for vacuum (and other uses will need a\\n> new function), let's assert the returned bool is false.\\n>\\n> Does iteration still work? If so, it's not too early to re-wire this\\n> up with vacuum and see how it behaves.\\n>\\n> Lastly, my compiler has a warning that CI doesn't have:\\n>\\n> In file included from ../src/test/modules/test_radixtree/test_radixtree.c:121:\\n> ../src/include/lib/radixtree.h: In function ‘rt_find.isra’:\\n> ../src/include/lib/radixtree.h:2142:24: warning: ‘slot’ may be used\\n> uninitialized [-Wmaybe-uninitialized]\\n> 2142 | return (RT_VALUE_TYPE*) slot;\\n> | ^~~~~~~~~~~~~~~~~~~~~\\n> ../src/include/lib/radixtree.h:2112:23: note: ‘slot’ was declared here\\n> 2112 | RT_PTR_ALLOC *slot;\\n> | ^~~~\\n\\nThank you for the comments! I agreed with all of them and incorporated\\nthem into the attached latest patch set, v45.\\n\\nIn v45, 0001 - 0006 are from earlier versions but I've merged previous\\nupdates. So the radix tree now has RT_SET() and RT_FIND() but not\\nRT_GET() and RT_SEARCH(). 0007 and 0008 are the updates from previous\\nversions that incorporated the above comments. 0009 patch integrates\\ntidstore with lazy vacuum. Note that DSA segment problem is not\\nresolved yet in this patch. 0010 and 0011 makes DSA initial/max\\nsegment size configurable and make parallel vacuum specify both in\\nproportion to maintenance_work_mem. 0012 is a development-purpose\\npatch to make it easy to investigate bugs in tidstore. I'd like to\\nkeep it in the patch set at least during the development.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 14 Dec 2023 09:22:11 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 14, 2023 at 7:22 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> In v45, 0001 - 0006 are from earlier versions but I've merged previous\\n> updates. So the radix tree now has RT_SET() and RT_FIND() but not\\n> RT_GET() and RT_SEARCH(). 0007 and 0008 are the updates from previous\\n> versions that incorporated the above comments. 0009 patch integrates\\n> tidstore with lazy vacuum.\\n\\nExcellent! I repeated a quick run of the small \\\"test 1\\\" with very low m_w_m from\\n\\nhttps://www.postgresql.org/message-id/CAFBsxsHrvTPUK%3DC1%3DxweJjGujja4Xjfgva3C8jnW3Shz6RBnFg%40mail.gmail.com\\n\\n...and got similar results, so we still have good space-efficiency on this test:\\n\\nmaster:\\nINFO: finished vacuuming \\\"john.public.test\\\": index scans: 9\\nsystem usage: CPU: user: 56.83 s, system: 9.36 s, elapsed: 119.62 s\\n\\nv45:\\nINFO: finished vacuuming \\\"john.public.test\\\": index scans: 1\\nsystem usage: CPU: user: 6.82 s, system: 2.05 s, elapsed: 10.89 s\\n\\nMore sparse TID distributions won't be as favorable, but we have ideas\\nto improve that in the future.\\n\\nFor my next steps, I will finish the node-shrinking behavior and save\\nfor a later patchset. Not needed for tid store, but needs to happen\\nbecause of assumptions in the code. Also, some time ago, I think I\\ncommented out RT_FREE_RECURSE to get something working, so I'll fix\\nit, and look at other fixmes and todos.\\n\\n> Note that DSA segment problem is not\\n> resolved yet in this patch.\\n\\nI remember you started a separate thread about this, but I don't think\\nit got any attention. Maybe reply with a \\\"TLDR;\\\" and share a patch to\\nallow controlling max segment size.\\n\\nSome more comments:\\n\\nv45-0003:\\n\\nSince RT_ITERATE_NEXT_PTR works for tid store, do we even need\\nRT_ITERATE_NEXT anymore? The former should handle fixed-length values\\njust fine? If so, we should rename it to match the latter.\\n\\n+ * The caller is responsible for locking/unlocking the tree in shared mode.\\n\\nThis is not new to v45, but this will come up again below. This needs\\nmore explanation: Since we're returning a pointer (to support\\nvariable-length values), the caller needs to maintain control until\\nit's finished with the value.\\n\\nv45-0005:\\n\\n+ * Regarding the concurrency support, we use a single LWLock for the TidStore.\\n+ * The TidStore is exclusively locked when inserting encoded tids to the\\n+ * radix tree or when resetting itself. When searching on the TidStore or\\n+ * doing the iteration, it is not locked but the underlying radix tree is\\n+ * locked in shared mode.\\n\\nThis is just stating facts without giving any reasons. Readers are\\ngoing to wonder why it's inconsistent. The \\\"why\\\" is much more\\nimportant than the \\\"what\\\". Even with that, this comment is also far\\nfrom the relevant parts, and so will get out of date. Maybe we can\\njust make sure each relevant function is explained individually.\\n\\nv45-0007:\\n\\n-RT_SCOPE RT_RADIX_TREE * RT_CREATE(MemoryContext ctx);\\n+RT_SCOPE RT_RADIX_TREE * RT_CREATE(MemoryContext ctx, Size work_mem);\\n\\nTid store calls this max_bytes -- can we use that name here, too?\\n\\\"work_mem\\\" is highly specific.\\n\\n- RT_PTR_ALLOC *slot;\\n+ RT_PTR_ALLOC *slot = NULL;\\n\\nWe have a macro for invalid pointer because of DSA.\\n\\nv45-0008:\\n\\n- if (off < 1 || off > MAX_TUPLES_PER_PAGE)\\n+ if (unlikely(off < 1 || off > MAX_TUPLES_PER_PAGE))\\n elog(ERROR, \\\"tuple offset out of range: %u\\\", off);\\n\\nThis is a superfluous distraction, since the error path is located way\\noff in the cold segment of the binary.\\n\\nv45-0009:\\n\\n(just a few small things for now)\\n\\n- * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in the\\n- * vacrel->dead_items array.\\n+ * lazy_vacuum_heap_page() -- free page's LP_DEAD items.\\n\\nI think we can keep as \\\"listed in the TID store\\\".\\n\\n- * Allocate dead_items (either using palloc, or in dynamic shared memory).\\n- * Sets dead_items in vacrel for caller.\\n+ * Allocate a (local or shared) TidStore for storing dead TIDs. Sets dead_items\\n+ * in vacrel for caller.\\n\\nI think we want to keep \\\"in dynamic shared memory\\\". It's still true.\\nI'm not sure anything needs to change here, actually.\\n\\n parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,\\n- int nrequested_workers, int max_items,\\n- int elevel, BufferAccessStrategy bstrategy)\\n+ int nrequested_workers, int vac_work_mem,\\n+ int max_offset, int elevel,\\n+ BufferAccessStrategy bstrategy)\\n\\nIt seems very strange to me that this function has to pass the\\nmax_offset. In general, it's been simpler to assume we have a constant\\nmax_offset, but in this case that fact is not helping. Something to\\nthink about for later.\\n\\n- (errmsg(\\\"scanned index \\\\\\\"%s\\\\\\\" to remove %d row versions\\\",\\n+ (errmsg(\\\"scanned index \\\\\\\"%s\\\\\\\" to remove \\\" UINT64_FORMAT \\\" row versions\\\",\\n\\nThis should be signed int64.\\n\\nv45-0010:\\n\\nThinking about this some more, I'm not sure we need to do anything\\ndifferent for the *starting* segment size. (Controlling *max* size\\ndoes seem important, however.) For the corner case of m_w_m = 1MB,\\nit's fine if vacuum quits pruning immediately after (in effect) it\\nfinds the DSA has gone to 2MB. It's not worth bothering with, IMO. If\\nthe memory accounting starts >1MB because we're adding the trivial\\nsize of some struct, let's just stop doing that. The segment\\nallocations are what we care about.\\n\\nv45-0011:\\n\\n+ /*\\n+ * max_bytes is forced to be at least 64kB, the current minimum valid\\n+ * value for the work_mem GUC.\\n+ */\\n+ max_bytes = Max(64 * 1024L, max_bytes);\\n\\nWhy? I believe I mentioned months ago that copying a hard-coded value\\nthat can get out of sync is not maintainable, but I don't even see the\\npoint of this part.\\n\\n\\n\",\n \"msg_date\": \"Fri, 15 Dec 2023 08:30:18 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 15, 2023 at 10:30 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Dec 14, 2023 at 7:22 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > In v45, 0001 - 0006 are from earlier versions but I've merged previous\\n> > updates. So the radix tree now has RT_SET() and RT_FIND() but not\\n> > RT_GET() and RT_SEARCH(). 0007 and 0008 are the updates from previous\\n> > versions that incorporated the above comments. 0009 patch integrates\\n> > tidstore with lazy vacuum.\\n>\\n> Excellent! I repeated a quick run of the small \\\"test 1\\\" with very low m_w_m from\\n>\\n> https://www.postgresql.org/message-id/CAFBsxsHrvTPUK%3DC1%3DxweJjGujja4Xjfgva3C8jnW3Shz6RBnFg%40mail.gmail.com\\n>\\n> ...and got similar results, so we still have good space-efficiency on this test:\\n>\\n> master:\\n> INFO: finished vacuuming \\\"john.public.test\\\": index scans: 9\\n> system usage: CPU: user: 56.83 s, system: 9.36 s, elapsed: 119.62 s\\n>\\n> v45:\\n> INFO: finished vacuuming \\\"john.public.test\\\": index scans: 1\\n> system usage: CPU: user: 6.82 s, system: 2.05 s, elapsed: 10.89 s\\n\\nThank you for testing it again. That's a very good result.\\n\\n> For my next steps, I will finish the node-shrinking behavior and save\\n> for a later patchset. Not needed for tid store, but needs to happen\\n> because of assumptions in the code. Also, some time ago, I think I\\n> commented out RT_FREE_RECURSE to get something working, so I'll fix\\n> it, and look at other fixmes and todos.\\n\\nGreat!\\n\\n>\\n> > Note that DSA segment problem is not\\n> > resolved yet in this patch.\\n>\\n> I remember you started a separate thread about this, but I don't think\\n> it got any attention. Maybe reply with a \\\"TLDR;\\\" and share a patch to\\n> allow controlling max segment size.\\n\\nYeah, I recalled that thread. Will send a reply.\\n\\n>\\n> Some more comments:\\n>\\n> v45-0003:\\n>\\n> Since RT_ITERATE_NEXT_PTR works for tid store, do we even need\\n> RT_ITERATE_NEXT anymore? The former should handle fixed-length values\\n> just fine? If so, we should rename it to match the latter.\\n\\nAgreed to rename it.\\n\\n>\\n> + * The caller is responsible for locking/unlocking the tree in shared mode.\\n>\\n> This is not new to v45, but this will come up again below. This needs\\n> more explanation: Since we're returning a pointer (to support\\n> variable-length values), the caller needs to maintain control until\\n> it's finished with the value.\\n\\nWill fix.\\n\\n>\\n> v45-0005:\\n>\\n> + * Regarding the concurrency support, we use a single LWLock for the TidStore.\\n> + * The TidStore is exclusively locked when inserting encoded tids to the\\n> + * radix tree or when resetting itself. When searching on the TidStore or\\n> + * doing the iteration, it is not locked but the underlying radix tree is\\n> + * locked in shared mode.\\n>\\n> This is just stating facts without giving any reasons. Readers are\\n> going to wonder why it's inconsistent. The \\\"why\\\" is much more\\n> important than the \\\"what\\\". Even with that, this comment is also far\\n> from the relevant parts, and so will get out of date. Maybe we can\\n> just make sure each relevant function is explained individually.\\n\\nRight, I'll fix it.\\n\\n>\\n> v45-0007:\\n>\\n> -RT_SCOPE RT_RADIX_TREE * RT_CREATE(MemoryContext ctx);\\n> +RT_SCOPE RT_RADIX_TREE * RT_CREATE(MemoryContext ctx, Size work_mem);\\n>\\n> Tid store calls this max_bytes -- can we use that name here, too?\\n> \\\"work_mem\\\" is highly specific.\\n\\nWhile I agree that \\\"work_mem\\\" is highly specific, I avoided using\\n\\\"max_bytes\\\" in radix tree because \\\"max_bytes\\\" sounds to me there is a\\nmemory limitation but the radix tree doesn't have it actually. It\\nmight be sufficient to mention it in the comment, though.\\n\\n>\\n> - RT_PTR_ALLOC *slot;\\n> + RT_PTR_ALLOC *slot = NULL;\\n>\\n> We have a macro for invalid pointer because of DSA.\\n\\nWill fix.\\n\\n>\\n> v45-0008:\\n>\\n> - if (off < 1 || off > MAX_TUPLES_PER_PAGE)\\n> + if (unlikely(off < 1 || off > MAX_TUPLES_PER_PAGE))\\n> elog(ERROR, \\\"tuple offset out of range: %u\\\", off);\\n>\\n> This is a superfluous distraction, since the error path is located way\\n> off in the cold segment of the binary.\\n\\nOkay, will remove it.\\n\\n>\\n> v45-0009:\\n>\\n> (just a few small things for now)\\n>\\n> - * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in the\\n> - * vacrel->dead_items array.\\n> + * lazy_vacuum_heap_page() -- free page's LP_DEAD items.\\n>\\n> I think we can keep as \\\"listed in the TID store\\\".\\n>\\n> - * Allocate dead_items (either using palloc, or in dynamic shared memory).\\n> - * Sets dead_items in vacrel for caller.\\n> + * Allocate a (local or shared) TidStore for storing dead TIDs. Sets dead_items\\n> + * in vacrel for caller.\\n>\\n> I think we want to keep \\\"in dynamic shared memory\\\". It's still true.\\n> I'm not sure anything needs to change here, actually.\\n\\nAgreed with above comments. Will fix them.\\n\\n>\\n> parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,\\n> - int nrequested_workers, int max_items,\\n> - int elevel, BufferAccessStrategy bstrategy)\\n> + int nrequested_workers, int vac_work_mem,\\n> + int max_offset, int elevel,\\n> + BufferAccessStrategy bstrategy)\\n>\\n> It seems very strange to me that this function has to pass the\\n> max_offset. In general, it's been simpler to assume we have a constant\\n> max_offset, but in this case that fact is not helping. Something to\\n> think about for later.\\n\\nmax_offset was previously used in old TID encoding in tidstore. Since\\ntidstore has entries for each block, I think we no longer need it.\\n\\n>\\n> - (errmsg(\\\"scanned index \\\\\\\"%s\\\\\\\" to remove %d row versions\\\",\\n> + (errmsg(\\\"scanned index \\\\\\\"%s\\\\\\\" to remove \\\" UINT64_FORMAT \\\" row versions\\\",\\n>\\n> This should be signed int64.\\n\\nWill fix.\\n\\n>\\n> v45-0010:\\n>\\n> Thinking about this some more, I'm not sure we need to do anything\\n> different for the *starting* segment size. (Controlling *max* size\\n> does seem important, however.) For the corner case of m_w_m = 1MB,\\n> it's fine if vacuum quits pruning immediately after (in effect) it\\n> finds the DSA has gone to 2MB. It's not worth bothering with, IMO. If\\n> the memory accounting starts >1MB because we're adding the trivial\\n> size of some struct, let's just stop doing that. The segment\\n> allocations are what we care about.\\n\\nIIUC it's for work_mem, whose the minimum value is 64kB.\\n\\n>\\n> v45-0011:\\n>\\n> + /*\\n> + * max_bytes is forced to be at least 64kB, the current minimum valid\\n> + * value for the work_mem GUC.\\n> + */\\n> + max_bytes = Max(64 * 1024L, max_bytes);\\n>\\n> Why?\\n\\nThis is to avoid creating a radix tree within very small memory. The\\nminimum work_mem value is a reasonable lower bound that PostgreSQL\\nuses internally. It's actually copied from tuplesort.c.\\n\\n>I believe I mentioned months ago that copying a hard-coded value\\n> that can get out of sync is not maintainable, but I don't even see the\\n> point of this part.\\n\\nTrue.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 15 Dec 2023 17:15:09 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Dec 15, 2023 at 3:15 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Dec 15, 2023 at 10:30 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,\\n> > - int nrequested_workers, int max_items,\\n> > - int elevel, BufferAccessStrategy bstrategy)\\n> > + int nrequested_workers, int vac_work_mem,\\n> > + int max_offset, int elevel,\\n> > + BufferAccessStrategy bstrategy)\\n> >\\n> > It seems very strange to me that this function has to pass the\\n> > max_offset. In general, it's been simpler to assume we have a constant\\n> > max_offset, but in this case that fact is not helping. Something to\\n> > think about for later.\\n>\\n> max_offset was previously used in old TID encoding in tidstore. Since\\n> tidstore has entries for each block, I think we no longer need it.\\n\\nIt's needed now to properly size the allocation of TidStoreIter which\\ncontains...\\n\\n+/* Result struct for TidStoreIterateNext */\\n+typedef struct TidStoreIterResult\\n+{\\n+ BlockNumber blkno;\\n+ int num_offsets;\\n+ OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];\\n+} TidStoreIterResult;\\n\\nMaybe we can palloc the offset array to \\\"almost always\\\" big enough,\\nwith logic to resize if needed? If not too hard, seems worth it to\\navoid churn in the parameter list.\\n\\n> > v45-0010:\\n> >\\n> > Thinking about this some more, I'm not sure we need to do anything\\n> > different for the *starting* segment size. (Controlling *max* size\\n> > does seem important, however.) For the corner case of m_w_m = 1MB,\\n> > it's fine if vacuum quits pruning immediately after (in effect) it\\n> > finds the DSA has gone to 2MB. It's not worth bothering with, IMO. If\\n> > the memory accounting starts >1MB because we're adding the trivial\\n> > size of some struct, let's just stop doing that. The segment\\n> > allocations are what we care about.\\n>\\n> IIUC it's for work_mem, whose the minimum value is 64kB.\\n>\\n> >\\n> > v45-0011:\\n> >\\n> > + /*\\n> > + * max_bytes is forced to be at least 64kB, the current minimum valid\\n> > + * value for the work_mem GUC.\\n> > + */\\n> > + max_bytes = Max(64 * 1024L, max_bytes);\\n> >\\n> > Why?\\n>\\n> This is to avoid creating a radix tree within very small memory. The\\n> minimum work_mem value is a reasonable lower bound that PostgreSQL\\n> uses internally. It's actually copied from tuplesort.c.\\n\\nThere is no explanation for why it should be done like tuplesort.c. Also...\\n\\n- tree->leaf_ctx = SlabContextCreate(ctx,\\n- \\\"radix tree leaves\\\",\\n- RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n- sizeof(RT_VALUE_TYPE));\\n+ tree->leaf_ctx = SlabContextCreate(ctx,\\n+ \\\"radix tree leaves\\\",\\n+ Min(RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n+ work_mem),\\n+ sizeof(RT_VALUE_TYPE));\\n\\nAt first, my eyes skipped over this apparent re-indent, but hidden\\ninside here is another (undocumented) attempt to clamp the size of\\nsomething. There are too many of these sprinkled in various places,\\nand they're already a maintenance hazard -- a different one was left\\nbehind in v45-0011:\\n\\n@@ -201,6 +183,7 @@ TidStoreCreate(size_t max_bytes, int max_off,\\ndsa_area *area)\\n ts->control->max_bytes = max_bytes - (70 * 1024);\\n }\\n\\nLet's do it in just one place. In TidStoreCreate(), do\\n\\n/* clamp max_bytes to at least the size of the empty tree with\\nallocated blocks, so it doesn't immediately appear full */\\nts->control->max_bytes = Max(max_bytes, {rt, shared_rt}_memory_usage);\\n\\nThen we can get rid of all the worry about 1MB/2MB, 64kB, 70kB -- all that.\\n\\nI may not recall everything while writing this, but it seems the only\\nother thing we should be clamping is the max aset block size (solved)\\n/ max DSM segment size (in progress).\\n\\n\\n\",\n \"msg_date\": \"Mon, 18 Dec 2023 13:41:35 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Dec 18, 2023 at 3:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Dec 15, 2023 at 3:15 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Dec 15, 2023 at 10:30 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,\\n> > > - int nrequested_workers, int max_items,\\n> > > - int elevel, BufferAccessStrategy bstrategy)\\n> > > + int nrequested_workers, int vac_work_mem,\\n> > > + int max_offset, int elevel,\\n> > > + BufferAccessStrategy bstrategy)\\n> > >\\n> > > It seems very strange to me that this function has to pass the\\n> > > max_offset. In general, it's been simpler to assume we have a constant\\n> > > max_offset, but in this case that fact is not helping. Something to\\n> > > think about for later.\\n> >\\n> > max_offset was previously used in old TID encoding in tidstore. Since\\n> > tidstore has entries for each block, I think we no longer need it.\\n>\\n> It's needed now to properly size the allocation of TidStoreIter which\\n> contains...\\n>\\n> +/* Result struct for TidStoreIterateNext */\\n> +typedef struct TidStoreIterResult\\n> +{\\n> + BlockNumber blkno;\\n> + int num_offsets;\\n> + OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];\\n> +} TidStoreIterResult;\\n>\\n> Maybe we can palloc the offset array to \\\"almost always\\\" big enough,\\n> with logic to resize if needed? If not too hard, seems worth it to\\n> avoid churn in the parameter list.\\n\\nYes, I was thinking of that.\\n\\n>\\n> > > v45-0010:\\n> > >\\n> > > Thinking about this some more, I'm not sure we need to do anything\\n> > > different for the *starting* segment size. (Controlling *max* size\\n> > > does seem important, however.) For the corner case of m_w_m = 1MB,\\n> > > it's fine if vacuum quits pruning immediately after (in effect) it\\n> > > finds the DSA has gone to 2MB. It's not worth bothering with, IMO. If\\n> > > the memory accounting starts >1MB because we're adding the trivial\\n> > > size of some struct, let's just stop doing that. The segment\\n> > > allocations are what we care about.\\n> >\\n> > IIUC it's for work_mem, whose the minimum value is 64kB.\\n> >\\n> > >\\n> > > v45-0011:\\n> > >\\n> > > + /*\\n> > > + * max_bytes is forced to be at least 64kB, the current minimum valid\\n> > > + * value for the work_mem GUC.\\n> > > + */\\n> > > + max_bytes = Max(64 * 1024L, max_bytes);\\n> > >\\n> > > Why?\\n> >\\n> > This is to avoid creating a radix tree within very small memory. The\\n> > minimum work_mem value is a reasonable lower bound that PostgreSQL\\n> > uses internally. It's actually copied from tuplesort.c.\\n>\\n> There is no explanation for why it should be done like tuplesort.c. Also...\\n>\\n> - tree->leaf_ctx = SlabContextCreate(ctx,\\n> - \\\"radix tree leaves\\\",\\n> - RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> - sizeof(RT_VALUE_TYPE));\\n> + tree->leaf_ctx = SlabContextCreate(ctx,\\n> + \\\"radix tree leaves\\\",\\n> + Min(RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> + work_mem),\\n> + sizeof(RT_VALUE_TYPE));\\n>\\n> At first, my eyes skipped over this apparent re-indent, but hidden\\n> inside here is another (undocumented) attempt to clamp the size of\\n> something. There are too many of these sprinkled in various places,\\n> and they're already a maintenance hazard -- a different one was left\\n> behind in v45-0011:\\n>\\n> @@ -201,6 +183,7 @@ TidStoreCreate(size_t max_bytes, int max_off,\\n> dsa_area *area)\\n> ts->control->max_bytes = max_bytes - (70 * 1024);\\n> }\\n>\\n> Let's do it in just one place. In TidStoreCreate(), do\\n>\\n> /* clamp max_bytes to at least the size of the empty tree with\\n> allocated blocks, so it doesn't immediately appear full */\\n> ts->control->max_bytes = Max(max_bytes, {rt, shared_rt}_memory_usage);\\n>\\n> Then we can get rid of all the worry about 1MB/2MB, 64kB, 70kB -- all that.\\n\\nBut doesn't it mean that even if we create a shared tidstore with\\nsmall memory, say 64kB, it actually uses 1MB?\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 19 Dec 2023 14:37:04 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 19, 2023 at 12:37 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Dec 18, 2023 at 3:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > Let's do it in just one place. In TidStoreCreate(), do\\n> >\\n> > /* clamp max_bytes to at least the size of the empty tree with\\n> > allocated blocks, so it doesn't immediately appear full */\\n> > ts->control->max_bytes = Max(max_bytes, {rt, shared_rt}_memory_usage);\\n> >\\n> > Then we can get rid of all the worry about 1MB/2MB, 64kB, 70kB -- all that.\\n>\\n> But doesn't it mean that even if we create a shared tidstore with\\n> small memory, say 64kB, it actually uses 1MB?\\n\\nThis sounds like an argument for controlling the minimum DSA segment\\nsize. (I'm not really in favor of that, but open to others' opinion)\\n\\nI wasn't talking about that above -- I was saying we should have only\\none place where we clamp max_bytes so that the tree doesn't\\nimmediately appear full.\\n\\n\\n\",\n \"msg_date\": \"Tue, 19 Dec 2023 14:36:52 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 19, 2023 at 4:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Dec 19, 2023 at 12:37 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Dec 18, 2023 at 3:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > Let's do it in just one place. In TidStoreCreate(), do\\n> > >\\n> > > /* clamp max_bytes to at least the size of the empty tree with\\n> > > allocated blocks, so it doesn't immediately appear full */\\n> > > ts->control->max_bytes = Max(max_bytes, {rt, shared_rt}_memory_usage);\\n> > >\\n> > > Then we can get rid of all the worry about 1MB/2MB, 64kB, 70kB -- all that.\\n> >\\n> > But doesn't it mean that even if we create a shared tidstore with\\n> > small memory, say 64kB, it actually uses 1MB?\\n>\\n> This sounds like an argument for controlling the minimum DSA segment\\n> size. (I'm not really in favor of that, but open to others' opinion)\\n>\\n> I wasn't talking about that above -- I was saying we should have only\\n> one place where we clamp max_bytes so that the tree doesn't\\n> immediately appear full.\\n\\nThank you for your clarification. Understood.\\n\\nI've updated the new patch set that incorporated comments I got so\\nfar. 0007, 0008, and 0012 patches are updates from the v45 patch set.\\nIn addition to the review comments, I made some changes in tidstore to\\nmake it independent from heap. Specifically, it uses MaxOffsetNumber\\ninstead of MaxHeapTuplesPerPage. Now we don't need to include\\nhtup_details.h. It enlarged MaxBlocktableEntrySize but it's still 272\\nbytes.\\n\\nBTW regarding the previous comment I got before:\\n\\n> - RT_PTR_ALLOC *slot;\\n> + RT_PTR_ALLOC *slot = NULL;\\n>\\n> We have a macro for invalid pointer because of DSA.\\n\\nI think that since *slot is a pointer to a RT_PTR_ALLOC it's okay to set NULL.\\n\\nAs for the initial and maximum DSA segment sizes, I've sent a summary\\non that thread:\\n\\nhttps://www.postgresql.org/message-id/CAD21AoCVMw6DSmgZY9h%2BxfzKtzJeqWiwxaUD2T-FztVcV-XibQ%40mail.gmail.com\\n\\nI'm going to update RT_DUMP() and RT_DUMP_NODE() codes for the next step.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 20 Dec 2023 20:35:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 20, 2023 at 6:36 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I've updated the new patch set that incorporated comments I got so\\n> far. 0007, 0008, and 0012 patches are updates from the v45 patch set.\\n> In addition to the review comments, I made some changes in tidstore to\\n> make it independent from heap. Specifically, it uses MaxOffsetNumber\\n> instead of MaxHeapTuplesPerPage. Now we don't need to include\\n> htup_details.h. It enlarged MaxBlocktableEntrySize but it's still 272\\n> bytes.\\n\\nThat's a good idea.\\n\\n> BTW regarding the previous comment I got before:\\n>\\n> > - RT_PTR_ALLOC *slot;\\n> > + RT_PTR_ALLOC *slot = NULL;\\n> >\\n> > We have a macro for invalid pointer because of DSA.\\n>\\n> I think that since *slot is a pointer to a RT_PTR_ALLOC it's okay to set NULL.\\n\\nAh right, it's the address of the slot.\\n\\n> I'm going to update RT_DUMP() and RT_DUMP_NODE() codes for the next step.\\n\\nThat could probably use some discussion. A few months ago, I found the\\ndebugging functions only worked when everything else worked. When\\nthings weren't working, I had to rip one of these functions apart so\\nit only looked at one node. If something is broken, we can't count on\\nrecursion or iteration working, because we won't get that far. I don't\\nremember how things are in the current patch.\\n\\nI've finished the node shrinking and addressed some fixme/todo areas\\n-- can I share these and squash your v46 changes first?\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Dec 2023 08:19:44 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 21, 2023 at 10:19 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Dec 20, 2023 at 6:36 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I've updated the new patch set that incorporated comments I got so\\n> > far. 0007, 0008, and 0012 patches are updates from the v45 patch set.\\n> > In addition to the review comments, I made some changes in tidstore to\\n> > make it independent from heap. Specifically, it uses MaxOffsetNumber\\n> > instead of MaxHeapTuplesPerPage. Now we don't need to include\\n> > htup_details.h. It enlarged MaxBlocktableEntrySize but it's still 272\\n> > bytes.\\n>\\n> That's a good idea.\\n>\\n> > BTW regarding the previous comment I got before:\\n> >\\n> > > - RT_PTR_ALLOC *slot;\\n> > > + RT_PTR_ALLOC *slot = NULL;\\n> > >\\n> > > We have a macro for invalid pointer because of DSA.\\n> >\\n> > I think that since *slot is a pointer to a RT_PTR_ALLOC it's okay to set NULL.\\n>\\n> Ah right, it's the address of the slot.\\n>\\n> > I'm going to update RT_DUMP() and RT_DUMP_NODE() codes for the next step.\\n>\\n> That could probably use some discussion. A few months ago, I found the\\n> debugging functions only worked when everything else worked. When\\n> things weren't working, I had to rip one of these functions apart so\\n> it only looked at one node. If something is broken, we can't count on\\n> recursion or iteration working, because we won't get that far. I don't\\n> remember how things are in the current patch.\\n\\nAgreed.\\n\\nI found the following comment and wanted to discuss:\\n\\n// this might be better as \\\"iterate over nodes\\\", plus a callback to\\nRT_DUMP_NODE,\\n// which should really only concern itself with single nodes\\nRT_SCOPE void\\nRT_DUMP(RT_RADIX_TREE *tree)\\n\\nIf it means we need to somehow use the iteration functions also for\\ndumping the whole tree, it would probably need to refactor the\\niteration codes so that the RT_DUMP() can use them while dumping\\nvisited nodes. But we need to be careful of not adding overheads to\\nthe iteration performance.\\n\\n>\\n> I've finished the node shrinking and addressed some fixme/todo areas\\n> -- can I share these and squash your v46 changes first?\\n\\nCool! Yes, please do so.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Dec 2023 10:32:37 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 21, 2023 at 8:33 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I found the following comment and wanted to discuss:\\n>\\n> // this might be better as \\\"iterate over nodes\\\", plus a callback to\\n> RT_DUMP_NODE,\\n> // which should really only concern itself with single nodes\\n> RT_SCOPE void\\n> RT_DUMP(RT_RADIX_TREE *tree)\\n>\\n> If it means we need to somehow use the iteration functions also for\\n> dumping the whole tree, it would probably need to refactor the\\n> iteration codes so that the RT_DUMP() can use them while dumping\\n> visited nodes. But we need to be careful of not adding overheads to\\n> the iteration performance.\\n\\nYeah, some months ago I thought a callback interface would make some\\nthings easier. I don't think we need that at the moment (possibly\\nnever), so that comment can be just removed. As far as these debug\\nfunctions, I only found useful the stats and dumping a single node,\\nFWIW.\\n\\nI've attached v47, which is v46 plus some fixes for radix tree.\\n\\n0004 - moves everything for \\\"delete\\\" to the end -- gradually other\\nthings will be grouped together in a sensible order\\n\\n0005 - trivial\\n\\n0006 - shrink nodes -- still needs testing, but nothing crashes yet.\\nThis shows some renaming might be good: Previously we had\\nRT_CHUNK_CHILDREN_ARRAY_COPY for growing nodes, but for shrinking I've\\nadded RT_COPY_ARRAYS_AND_DELETE, since the deletion happens by simply\\nnot copying the slot to be deleted. This means when growing it would\\nbe more clear to call the former RT_COPY_ARRAYS_FOR_INSERT, since that\\nreserves a new slot for the caller in the new node, but the caller\\nmust do the insert itself. Note that there are some practical\\nrestrictions/best-practices on whether shrinking should happen after\\ndeletion or vice versa. Hopefully it's clear, but let me know if the\\ndescription can be improved. Also, it doesn't yet shrink from size\\nclass 32 to 16, but it could with a bit of work.\\n\\n0007 - trivial, but could use a better comment. I also need to make\\nsure stats reporting works (may also need some cleanup work).\\n\\n0008 - fixes RT_FREE_RECURSE -- I believe you wondered some months ago\\nif DSA could just free all our allocated segments without throwing\\naway the DSA, and that's still a good question.\\n\\n0009 - fixes the assert in RT_ITER_SET_NODE_FROM (btw, I don't think\\nthis name is better than RT_UPDATE_ITER_STACK, so maybe we should go\\nback to that). The assert doesn't fire, so I guess it does what it's\\nsupposed to? For me, the iteration logic is still the most confusing\\npiece out of the whole radix tree. Maybe that could be helped with\\nsome better variable names, but I wonder if it needs more invasive\\nwork. I confess I don't have better ideas for how it would work\\ndifferently.\\n\\n0010 - some fixes for number of children accounting in node256\\n\\n0011 - Long overdue pgindent of radixtree.h, without trying to fix up\\nafterwards. Feel free to throw out and redo if this interferes with\\nongoing work.\\n\\nThe rest are from your v46. The bench doesn't work for tid store\\nanymore, so I squashed \\\"disable bench for CI\\\" until we get back to\\nthat. Some more review comments (note: patch numbers are for v47, but\\nI changed nothing from v46 in this area):\\n\\n0013:\\n\\n+ * Internally, a tid is encoded as a pair of 64-bit key and 64-bit value,\\n+ * and stored in the radix tree.\\n\\nRecently outdated. The variable length values seems to work, so let's\\nmake everything match.\\n\\n+#define MAX_TUPLES_PER_PAGE MaxOffsetNumber\\n\\nMaybe we don't need this macro anymore? The name no longer fits, in any case.\\n\\n+TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n+ int num_offsets)\\n+{\\n+ char buf[MaxBlocktableEntrySize];\\n+ BlocktableEntry *page = (BlocktableEntry *) buf;\\n\\nI'm not sure this is safe with alignment. Maybe rather than plain\\n\\\"char\\\", it needs to be a union with BlocktableEntry, or something.\\n\\n+static inline BlocktableEntry *\\n+tidstore_iter_kv(TidStoreIter *iter, uint64 *key)\\n+{\\n+ if (TidStoreIsShared(iter->ts))\\n+ return shared_rt_iterate_next(iter->tree_iter.shared, key);\\n+\\n+ return local_rt_iterate_next(iter->tree_iter.local, key);\\n+}\\n\\nIn the old encoding scheme, this function did something important, but\\nnow it's a useless wrapper with one caller.\\n\\n+ /*\\n+ * In the shared case, TidStoreControl and radix_tree are backed by the\\n+ * same DSA area and rt_memory_usage() returns the value including both.\\n+ * So we don't need to add the size of TidStoreControl separately.\\n+ */\\n+ if (TidStoreIsShared(ts))\\n+ return sizeof(TidStore) + shared_rt_memory_usage(ts->tree.shared);\\n+\\n+ return sizeof(TidStore) + sizeof(TidStore) +\\nlocal_rt_memory_usage(ts->tree.local);\\n\\nI don't see the point in including these tiny structs, since we will\\nalways blow past the limit by a number of kilobytes (at least, often\\nmegabytes or more) at the time it happens.\\n\\n+ iter->output.max_offset = 64;\\n\\nMaybe needs a comment that this is just some starting size and not\\nanything particular.\\n\\n+ iter->output.offsets = palloc(sizeof(OffsetNumber) * iter->output.max_offset);\\n\\n+ /* Make sure there is enough space to add offsets */\\n+ if (result->num_offsets + bmw_popcount(w) > result->max_offset)\\n+ {\\n+ result->max_offset *= 2;\\n+ result->offsets = repalloc(result->offsets,\\n+ sizeof(OffsetNumber) * result->max_offset);\\n+ }\\n\\npopcount()-ing for every array element in every value is expensive --\\nlet's just add sizeof(bitmapword). It's not that wasteful, but then\\nthe initial max will need to be 128.\\n\\nAbout separation of responsibilities for locking: The only thing\\ncurrently where the tid store is not locked is tree iteration. That's\\na strange exception. Also, we've recently made RT_FIND return a\\npointer, so the caller must somehow hold a share lock, but I think we\\nhaven't exposed callers the ability to do that, and we rely on the tid\\nstore lock for that. We have a mix of tree locking and tid store\\nlocking. We will need to consider carefully how to make this more\\nclear, maintainable, and understandable.\\n\\n0015:\\n\\n\\\"XXX: some regression test fails since this commit changes the minimum\\nm_w_m to 2048 from 1024. This was necessary for the pervious memory\\\"\\n\\nThis shouldn't fail anymore if the \\\"one-place\\\" clamp was in a patch\\nbefore this. If so, lets take out that GUC change and worry about\\nmin/max size separately. If it still fails, I'd like to know why.\\n\\n- * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in the\\n- * vacrel->dead_items array.\\n+ * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in\\nthe TID store.\\n\\nWhat I was getting at earlier is that the first line here doesn't\\nreally need to change, we can just s/array/store/ ?\\n\\n-static int\\n-lazy_vacuum_heap_page(LVRelState *vacrel, BlockNumber blkno, Buffer buffer,\\n- int index, Buffer vmbuffer)\\n+static void\\n+lazy_vacuum_heap_page(LVRelState *vacrel, BlockNumber blkno,\\n+ OffsetNumber *deadoffsets,\\nint num_offsets, Buffer buffer,\\n+ Buffer vmbuffer)\\n\\n\\\"buffer\\\" should still come after \\\"blkno\\\", so that line doesn't need to change.\\n\\n$ git diff master -- src/backend/access/heap/ | grep has_lpdead_items\\n- bool has_lpdead_items; /* includes existing LP_DEAD items */\\n- * pruning and freezing. all_visible implies !has_lpdead_items, but don't\\n- Assert(!prunestate.all_visible || !prunestate.has_lpdead_items);\\n- if (prunestate.has_lpdead_items)\\n- else if (prunestate.has_lpdead_items && PageIsAllVisible(page))\\n- if (prunestate.has_lpdead_items && vacrel->do_index_vacuuming)\\n- prunestate->has_lpdead_items = false;\\n- prunestate->has_lpdead_itemshas_lpdead_itemshas_lpdead_itemshas_lpdead_items\\n= true;\\n\\nIn a green field, it'd be fine to replace these with an expression of\\n\\\"num_offsets\\\", but it adds a bit of noise for reviewers and the git\\nlog. Is it really necessary?\\n\\n- deadoffsets[lpdead_items++] = offnum;\\n+\\nprunestate->deadoffsets[prunestate->num_offsets++] = offnum;\\n\\n I'm also not quite sure why \\\"deadoffsets\\\" and \\\"lpdead_items\\\" got\\nmoved to the PruneState. The latter was renamed in a way that makes\\nmore sense, but I don't see why the churn is necessary.\\n\\n@@ -1875,28 +1882,9 @@ lazy_scan_prune(LVRelState *vacrel,\\n }\\n #endif\\n\\n- /*\\n- * Now save details of the LP_DEAD items from the page in vacrel\\n- */\\n- if (lpdead_items > 0)\\n+ if (prunestate->num_offsets > 0)\\n {\\n- VacDeadItems *dead_items = vacrel->dead_items;\\n- ItemPointerData tmp;\\n-\\n vacrel->lpdead_item_pages++;\\n- prunestate->has_lpdead_items = true;\\n-\\n- ItemPointerSetBlockNumber(&tmp, blkno);\\n-\\n- for (int i = 0; i < lpdead_items; i++)\\n- {\\n- ItemPointerSetOffsetNumber(&tmp, deadoffsets[i]);\\n- dead_items->items[dead_items->num_items++] = tmp;\\n- }\\n-\\n- Assert(dead_items->num_items <= dead_items->max_items);\\n- pgstat_progress_update_param(PROGRESS_VACUUM_NUM_DEAD_TUPLES,\\n-\\n dead_items->num_items);\\n\\nI don't understand why this block got removed and nothing new is\\nadding anything to the tid store.\\n\\n@@ -1087,7 +1088,16 @@ lazy_scan_heap(LVRelState *vacrel)\\n * with prunestate-driven visibility map and\\nFSM steps (just like\\n * the two-pass strategy).\\n */\\n- Assert(dead_items->num_items == 0);\\n+ Assert(TidStoreNumTids(dead_items) == 0);\\n+ }\\n+ else if (prunestate.num_offsets > 0)\\n+ {\\n+ /* Save details of the LP_DEAD items from the\\npage in dead_items */\\n+ TidStoreSetBlockOffsets(dead_items, blkno,\\nprunestate.deadoffsets,\\n+\\n prunestate.num_offsets);\\n+\\n+\\npgstat_progress_update_param(PROGRESS_VACUUM_DEAD_TUPLE_BYTES,\\n+\\n TidStoreMemoryUsage(dead_items));\\n\\nI guess it was added here, 800 lines away? If so, why?\\n\\nAbout progress reporting: I want to make sure no one is going to miss\\ncounting \\\"num_dead_tuples\\\". It's no longer relevant for the number of\\nindex scans we need to do, but do admins still have a use for it?\\nSomething to think about later.\\n\\n0017\\n\\n+ /*\\n+ * max_bytes is forced to be at least 64kB, the current minimum valid\\n+ * value for the work_mem GUC.\\n+ */\\n+ max_bytes = Max(64 * 1024L, max_bytes);\\n\\nIf this still needs to be here, I still don't understand why.\",\n \"msg_date\": \"Thu, 21 Dec 2023 14:41:37 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2023-12-21 14:41:37 +0700, John Naylor wrote:\\n> I've attached v47, which is v46 plus some fixes for radix tree.\\n\\nCould either of you summarize what the design changes you've made in the last\\nmonths are and why you've done them? Unfortunately this thread is very long,\\nand the comments in the file just say \\\"FIXME\\\" in places that apparently are\\naffected by design changes. This makes it hard to catch up here.\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Dec 2023 03:27:41 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 21, 2023 at 6:27 PM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> Could either of you summarize what the design changes you've made in the last\\n> months are and why you've done them? Unfortunately this thread is very long,\\n> and the comments in the file just say \\\"FIXME\\\" in places that apparently are\\n> affected by design changes. This makes it hard to catch up here.\\n\\nI'd be happy to try, since we are about due for a summary. I was also\\nhoping to reach a coherent-enough state sometime in early January to\\nrequest your feedback, so good timing. Not sure how much detail to go\\ninto, but here goes:\\n\\nBack in May [1], the method of value storage shifted towards \\\"combined\\npointer-value slots\\\", which was described and recommended in the\\npaper. There were some other changes for simplicity and efficiency,\\nbut none as far-reaching as this.\\n\\nThis is enabled by using the template architecture that we adopted\\nlong ago for different reasons. Fixed length values are either stored\\nin the slot of the last-level node (if the value fits into the\\nplatform's pointer), or are a \\\"single-value\\\" leaf (otherwise).\\n\\nFor tid store, we want to eventually support bitmap heap scans (in\\naddition to vacuum), and in doing so make it independent of heap AM.\\nThat means value types similar to PageTableEntry tidbitmap.c, but with\\na variable number of bitmapwords.\\n\\nThat required radix tree to support variable length values. That has\\nbeen the main focus in the last several months, and it basically works\\nnow.\\n\\nTo my mind, the biggest architectural issues in the patch today are:\\n\\n- Variable-length values means that pointers are passed around in\\nplaces. This will require some shifting responsibility for locking to\\nthe caller, or longer-term maybe a callback interface. (This is new,\\nthe below are pre-existing issues.)\\n- The tid store has its own \\\"control object\\\" (when shared memory is\\nneeded) with its own lock, in addition to the same for the associated\\nradix tree. This leads to unnecessary double-locking. This area needs\\nsome attention.\\n- Memory accounting is still unsettled. The current thinking is to cap\\nmax block/segment size, scaled to a fraction of m_w_m, but there are\\nstill open questions.\\n\\nThere has been some recent effort toward finishing work started\\nearlier, like shrinking nodes. There a couple places that can still\\nuse either simplification or optimization, but otherwise work fine.\\nMost of the remaining fixmes/todos/wips are trivial; a few are\\nactually outdated now that I look again, and will be removed shortly.\\nThe regression tests could use some tidying up.\\n\\n-John\\n\\n[1] https://www.postgresql.org/message-id/CAFBsxsFyWLxweHVDtKb7otOCR4XdQGYR4b%2B9svxpVFnJs08BmQ%40mail.gmail.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 22 Dec 2023 21:09:33 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Dec 21, 2023 at 4:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Dec 21, 2023 at 8:33 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I found the following comment and wanted to discuss:\\n> >\\n> > // this might be better as \\\"iterate over nodes\\\", plus a callback to\\n> > RT_DUMP_NODE,\\n> > // which should really only concern itself with single nodes\\n> > RT_SCOPE void\\n> > RT_DUMP(RT_RADIX_TREE *tree)\\n> >\\n> > If it means we need to somehow use the iteration functions also for\\n> > dumping the whole tree, it would probably need to refactor the\\n> > iteration codes so that the RT_DUMP() can use them while dumping\\n> > visited nodes. But we need to be careful of not adding overheads to\\n> > the iteration performance.\\n>\\n> Yeah, some months ago I thought a callback interface would make some\\n> things easier. I don't think we need that at the moment (possibly\\n> never), so that comment can be just removed. As far as these debug\\n> functions, I only found useful the stats and dumping a single node,\\n> FWIW.\\n>\\n> I've attached v47, which is v46 plus some fixes for radix tree.\\n>\\n> 0004 - moves everything for \\\"delete\\\" to the end -- gradually other\\n> things will be grouped together in a sensible order\\n>\\n> 0005 - trivial\\n\\nLGTM.\\n\\n>\\n> 0006 - shrink nodes -- still needs testing, but nothing crashes yet.\\n\\nCool. The coverage test results showed the shrink codes are also covered.\\n\\n> This shows some renaming might be good: Previously we had\\n> RT_CHUNK_CHILDREN_ARRAY_COPY for growing nodes, but for shrinking I've\\n> added RT_COPY_ARRAYS_AND_DELETE, since the deletion happens by simply\\n> not copying the slot to be deleted. This means when growing it would\\n> be more clear to call the former RT_COPY_ARRAYS_FOR_INSERT, since that\\n> reserves a new slot for the caller in the new node, but the caller\\n> must do the insert itself.\\n\\nAgreed.\\n\\n> Note that there are some practical\\n> restrictions/best-practices on whether shrinking should happen after\\n> deletion or vice versa. Hopefully it's clear, but let me know if the\\n> description can be improved. Also, it doesn't yet shrink from size\\n> class 32 to 16, but it could with a bit of work.\\n\\nSounds reasonable.\\n\\n>\\n> 0007 - trivial, but could use a better comment. I also need to make\\n> sure stats reporting works (may also need some cleanup work).\\n>\\n> 0008 - fixes RT_FREE_RECURSE -- I believe you wondered some months ago\\n> if DSA could just free all our allocated segments without throwing\\n> away the DSA, and that's still a good question.\\n\\nLGTM.\\n\\n>\\n> 0009 - fixes the assert in RT_ITER_SET_NODE_FROM (btw, I don't think\\n> this name is better than RT_UPDATE_ITER_STACK, so maybe we should go\\n> back to that).\\n\\nWill rename it.\\n\\n> The assert doesn't fire, so I guess it does what it's\\n> supposed to?\\n\\nYes.\\n\\n> For me, the iteration logic is still the most confusing\\n> piece out of the whole radix tree. Maybe that could be helped with\\n> some better variable names, but I wonder if it needs more invasive\\n> work.\\n\\nTrue. Maybe more comments would also help.\\n\\n>\\n> 0010 - some fixes for number of children accounting in node256\\n>\\n> 0011 - Long overdue pgindent of radixtree.h, without trying to fix up\\n> afterwards. Feel free to throw out and redo if this interferes with\\n> ongoing work.\\n>\\n\\nLGTM.\\n\\nI'm working on the below review comments and most of them are already\\nincorporated on the local branch:\\n\\n> The rest are from your v46. The bench doesn't work for tid store\\n> anymore, so I squashed \\\"disable bench for CI\\\" until we get back to\\n> that. Some more review comments (note: patch numbers are for v47, but\\n> I changed nothing from v46 in this area):\\n>\\n> 0013:\\n>\\n> + * Internally, a tid is encoded as a pair of 64-bit key and 64-bit value,\\n> + * and stored in the radix tree.\\n>\\n> Recently outdated. The variable length values seems to work, so let's\\n> make everything match.\\n>\\n> +#define MAX_TUPLES_PER_PAGE MaxOffsetNumber\\n>\\n> Maybe we don't need this macro anymore? The name no longer fits, in any case.\\n\\nRemoved.\\n\\n>\\n> +TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n> + int num_offsets)\\n> +{\\n> + char buf[MaxBlocktableEntrySize];\\n> + BlocktableEntry *page = (BlocktableEntry *) buf;\\n>\\n> I'm not sure this is safe with alignment. Maybe rather than plain\\n> \\\"char\\\", it needs to be a union with BlocktableEntry, or something.\\n\\nI tried it in the new patch set but could you explain why it could not\\nbe safe with alignment?\\n\\n>\\n> +static inline BlocktableEntry *\\n> +tidstore_iter_kv(TidStoreIter *iter, uint64 *key)\\n> +{\\n> + if (TidStoreIsShared(iter->ts))\\n> + return shared_rt_iterate_next(iter->tree_iter.shared, key);\\n> +\\n> + return local_rt_iterate_next(iter->tree_iter.local, key);\\n> +}\\n>\\n> In the old encoding scheme, this function did something important, but\\n> now it's a useless wrapper with one caller.\\n\\nRemoved.\\n\\n>\\n> + /*\\n> + * In the shared case, TidStoreControl and radix_tree are backed by the\\n> + * same DSA area and rt_memory_usage() returns the value including both.\\n> + * So we don't need to add the size of TidStoreControl separately.\\n> + */\\n> + if (TidStoreIsShared(ts))\\n> + return sizeof(TidStore) + shared_rt_memory_usage(ts->tree.shared);\\n> +\\n> + return sizeof(TidStore) + sizeof(TidStore) +\\n> local_rt_memory_usage(ts->tree.local);\\n>\\n> I don't see the point in including these tiny structs, since we will\\n> always blow past the limit by a number of kilobytes (at least, often\\n> megabytes or more) at the time it happens.\\n\\nAgreed, removed.\\n\\n>\\n> + iter->output.max_offset = 64;\\n>\\n> Maybe needs a comment that this is just some starting size and not\\n> anything particular.\\n>\\n> + iter->output.offsets = palloc(sizeof(OffsetNumber) * iter->output.max_offset);\\n>\\n> + /* Make sure there is enough space to add offsets */\\n> + if (result->num_offsets + bmw_popcount(w) > result->max_offset)\\n> + {\\n> + result->max_offset *= 2;\\n> + result->offsets = repalloc(result->offsets,\\n> + sizeof(OffsetNumber) * result->max_offset);\\n> + }\\n>\\n> popcount()-ing for every array element in every value is expensive --\\n> let's just add sizeof(bitmapword). It's not that wasteful, but then\\n> the initial max will need to be 128.\\n\\nGood idea.\\n\\n>\\n> About separation of responsibilities for locking: The only thing\\n> currently where the tid store is not locked is tree iteration. That's\\n> a strange exception. Also, we've recently made RT_FIND return a\\n> pointer, so the caller must somehow hold a share lock, but I think we\\n> haven't exposed callers the ability to do that, and we rely on the tid\\n> store lock for that. We have a mix of tree locking and tid store\\n> locking. We will need to consider carefully how to make this more\\n> clear, maintainable, and understandable.\\n\\nYes, tidstore should be locked during the iteration.\\n\\nOne simple direction about locking is that the radix tree has the lock\\nbut no APIs hold/release it. It's the caller's responsibility. If a\\ndata structure using a radix tree for its storage has its own lock\\n(like tidstore), it can use it instead of the radix tree's one. A\\ndownside would be that it's probably hard to support a better locking\\nalgorithm such as ROWEX in the radix tree. Another variant of APIs\\nthat also does locking/unlocking within APIs might help.\\n\\n>\\n> 0015:\\n>\\n> \\\"XXX: some regression test fails since this commit changes the minimum\\n> m_w_m to 2048 from 1024. This was necessary for the pervious memory\\\"\\n>\\n> This shouldn't fail anymore if the \\\"one-place\\\" clamp was in a patch\\n> before this. If so, lets take out that GUC change and worry about\\n> min/max size separately. If it still fails, I'd like to know why.\\n\\nAgreed.\\n\\n>\\n> - * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in the\\n> - * vacrel->dead_items array.\\n> + * lazy_vacuum_heap_page() -- free page's LP_DEAD items listed in\\n> the TID store.\\n>\\n> What I was getting at earlier is that the first line here doesn't\\n> really need to change, we can just s/array/store/ ?\\n\\nFixed.\\n\\n>\\n> -static int\\n> -lazy_vacuum_heap_page(LVRelState *vacrel, BlockNumber blkno, Buffer buffer,\\n> - int index, Buffer vmbuffer)\\n> +static void\\n> +lazy_vacuum_heap_page(LVRelState *vacrel, BlockNumber blkno,\\n> + OffsetNumber *deadoffsets,\\n> int num_offsets, Buffer buffer,\\n> + Buffer vmbuffer)\\n>\\n> \\\"buffer\\\" should still come after \\\"blkno\\\", so that line doesn't need to change.\\n\\nFixed.\\n\\n>\\n> $ git diff master -- src/backend/access/heap/ | grep has_lpdead_items\\n> - bool has_lpdead_items; /* includes existing LP_DEAD items */\\n> - * pruning and freezing. all_visible implies !has_lpdead_items, but don't\\n> - Assert(!prunestate.all_visible || !prunestate.has_lpdead_items);\\n> - if (prunestate.has_lpdead_items)\\n> - else if (prunestate.has_lpdead_items && PageIsAllVisible(page))\\n> - if (prunestate.has_lpdead_items && vacrel->do_index_vacuuming)\\n> - prunestate->has_lpdead_items = false;\\n> - prunestate->has_lpdead_itemshas_lpdead_itemshas_lpdead_itemshas_lpdead_items\\n> = true;\\n>\\n> In a green field, it'd be fine to replace these with an expression of\\n> \\\"num_offsets\\\", but it adds a bit of noise for reviewers and the git\\n> log. Is it really necessary?\\n\\nI see your point. I think we can live with having both\\nhas_lpdead_items and num_offsets. But we will have to check if these\\nvalues are consistent, which could be less maintainable.\\n\\n>\\n> - deadoffsets[lpdead_items++] = offnum;\\n> +\\n> prunestate->deadoffsets[prunestate->num_offsets++] = offnum;\\n>\\n> I'm also not quite sure why \\\"deadoffsets\\\" and \\\"lpdead_items\\\" got\\n> moved to the PruneState. The latter was renamed in a way that makes\\n> more sense, but I don't see why the churn is necessary.\\n>\\n> @@ -1875,28 +1882,9 @@ lazy_scan_prune(LVRelState *vacrel,\\n> }\\n> #endif\\n>\\n> - /*\\n> - * Now save details of the LP_DEAD items from the page in vacrel\\n> - */\\n> - if (lpdead_items > 0)\\n> + if (prunestate->num_offsets > 0)\\n> {\\n> - VacDeadItems *dead_items = vacrel->dead_items;\\n> - ItemPointerData tmp;\\n> -\\n> vacrel->lpdead_item_pages++;\\n> - prunestate->has_lpdead_items = true;\\n> -\\n> - ItemPointerSetBlockNumber(&tmp, blkno);\\n> -\\n> - for (int i = 0; i < lpdead_items; i++)\\n> - {\\n> - ItemPointerSetOffsetNumber(&tmp, deadoffsets[i]);\\n> - dead_items->items[dead_items->num_items++] = tmp;\\n> - }\\n> -\\n> - Assert(dead_items->num_items <= dead_items->max_items);\\n> - pgstat_progress_update_param(PROGRESS_VACUUM_NUM_DEAD_TUPLES,\\n> -\\n> dead_items->num_items);\\n>\\n> I don't understand why this block got removed and nothing new is\\n> adding anything to the tid store.\\n>\\n> @@ -1087,7 +1088,16 @@ lazy_scan_heap(LVRelState *vacrel)\\n> * with prunestate-driven visibility map and\\n> FSM steps (just like\\n> * the two-pass strategy).\\n> */\\n> - Assert(dead_items->num_items == 0);\\n> + Assert(TidStoreNumTids(dead_items) == 0);\\n> + }\\n> + else if (prunestate.num_offsets > 0)\\n> + {\\n> + /* Save details of the LP_DEAD items from the\\n> page in dead_items */\\n> + TidStoreSetBlockOffsets(dead_items, blkno,\\n> prunestate.deadoffsets,\\n> +\\n> prunestate.num_offsets);\\n> +\\n> +\\n> pgstat_progress_update_param(PROGRESS_VACUUM_DEAD_TUPLE_BYTES,\\n> +\\n> TidStoreMemoryUsage(dead_items));\\n>\\n> I guess it was added here, 800 lines away? If so, why?\\n\\nThe above changes are related. The idea is not to use tidstore in a\\none-pass strategy. If the table doesn't have any indexes, in\\nlazy_scan_prune() we collect offset numbers of dead tuples on the page\\nand vacuum the page using them. In this case, we don't need to use\\ntidstore so we pass the offsets array to lazy_vacuum_heap_page(). The\\nLVPagePruneState is a convenient place to store collected offset\\nnumbers.\\n\\n>\\n> About progress reporting: I want to make sure no one is going to miss\\n> counting \\\"num_dead_tuples\\\". It's no longer relevant for the number of\\n> index scans we need to do, but do admins still have a use for it?\\n> Something to think about later.\\n\\nI'm not sure if the user will still need num_dead_tuples in progress\\nreporting view. The total number of dead tuples might be useful but\\nthe verbose log already shows that.\\n\\n>\\n> 0017\\n>\\n> + /*\\n> + * max_bytes is forced to be at least 64kB, the current minimum valid\\n> + * value for the work_mem GUC.\\n> + */\\n> + max_bytes = Max(64 * 1024L, max_bytes);\\n>\\n> If this still needs to be here, I still don't understand why.\\n\\nRemoved.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 26 Dec 2023 14:42:24 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Dec 26, 2023 at 12:43 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Dec 21, 2023 at 4:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > +TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n> > + int num_offsets)\\n> > +{\\n> > + char buf[MaxBlocktableEntrySize];\\n> > + BlocktableEntry *page = (BlocktableEntry *) buf;\\n> >\\n> > I'm not sure this is safe with alignment. Maybe rather than plain\\n> > \\\"char\\\", it needs to be a union with BlocktableEntry, or something.\\n>\\n> I tried it in the new patch set but could you explain why it could not\\n> be safe with alignment?\\n\\nI was thinking because \\\"buf\\\" is just an array of bytes. But, since the\\nnext declaration is a cast to a pointer to the actual type, maybe we\\ncan rely on the compiler to do the right thing. (It seems to on my\\nmachine in any case)\\n\\n> > About separation of responsibilities for locking: The only thing\\n> > currently where the tid store is not locked is tree iteration. That's\\n> > a strange exception. Also, we've recently made RT_FIND return a\\n> > pointer, so the caller must somehow hold a share lock, but I think we\\n> > haven't exposed callers the ability to do that, and we rely on the tid\\n> > store lock for that. We have a mix of tree locking and tid store\\n> > locking. We will need to consider carefully how to make this more\\n> > clear, maintainable, and understandable.\\n>\\n> Yes, tidstore should be locked during the iteration.\\n>\\n> One simple direction about locking is that the radix tree has the lock\\n> but no APIs hold/release it. It's the caller's responsibility. If a\\n> data structure using a radix tree for its storage has its own lock\\n> (like tidstore), it can use it instead of the radix tree's one. A\\n\\nIt looks like the only reason tidstore has its own lock is because it\\nhas no way to delegate locking to the tree's lock. Instead of working\\naround the limitations of the thing we've designed, let's make it work\\nfor the one use case we have. I think we need to expose RT_LOCK_*\\nfunctions to the outside, and have tid store use them. That would\\nallow us to simplify all those \\\"if (TidStoreIsShared(ts)\\nLWLockAcquire(..., ...)\\\" calls, which are complex and often redundant.\\n\\nAt some point, we'll probably want to keep locking inside, at least to\\nsmooth the way for fine-grained locking you mentioned.\\n\\n> > In a green field, it'd be fine to replace these with an expression of\\n> > \\\"num_offsets\\\", but it adds a bit of noise for reviewers and the git\\n> > log. Is it really necessary?\\n>\\n> I see your point. I think we can live with having both\\n> has_lpdead_items and num_offsets. But we will have to check if these\\n> values are consistent, which could be less maintainable.\\n\\nIt would be clearer if that removal was split out into a separate patch.\\n\\n> > I'm also not quite sure why \\\"deadoffsets\\\" and \\\"lpdead_items\\\" got\\n> > moved to the PruneState. The latter was renamed in a way that makes\\n> > more sense, but I don't see why the churn is necessary.\\n...\\n> > I guess it was added here, 800 lines away? If so, why?\\n>\\n> The above changes are related. The idea is not to use tidstore in a\\n> one-pass strategy. If the table doesn't have any indexes, in\\n> lazy_scan_prune() we collect offset numbers of dead tuples on the page\\n> and vacuum the page using them. In this case, we don't need to use\\n> tidstore so we pass the offsets array to lazy_vacuum_heap_page(). The\\n> LVPagePruneState is a convenient place to store collected offset\\n> numbers.\\n\\nOkay, that makes sense, but if it was ever explained, I don't\\nremember, and there is nothing in the commit message either.\\n\\nI'm not sure this can be split up easily, but if so it might help reviewing.\\n\\nThis change also leads to a weird-looking control flow:\\n\\nif (vacrel->nindexes == 0)\\n{\\n if (prunestate.num_offsets > 0)\\n {\\n ...\\n }\\n}\\nelse if (prunestate.num_offsets > 0)\\n{\\n ...\\n}\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Dec 2023 10:07:48 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Dec 27, 2023 at 12:08 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Dec 26, 2023 at 12:43 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Dec 21, 2023 at 4:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > +TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n> > > + int num_offsets)\\n> > > +{\\n> > > + char buf[MaxBlocktableEntrySize];\\n> > > + BlocktableEntry *page = (BlocktableEntry *) buf;\\n> > >\\n> > > I'm not sure this is safe with alignment. Maybe rather than plain\\n> > > \\\"char\\\", it needs to be a union with BlocktableEntry, or something.\\n> >\\n> > I tried it in the new patch set but could you explain why it could not\\n> > be safe with alignment?\\n>\\n> I was thinking because \\\"buf\\\" is just an array of bytes. But, since the\\n> next declaration is a cast to a pointer to the actual type, maybe we\\n> can rely on the compiler to do the right thing. (It seems to on my\\n> machine in any case)\\n\\nOkay, I kept it.\\n\\n>\\n> > > About separation of responsibilities for locking: The only thing\\n> > > currently where the tid store is not locked is tree iteration. That's\\n> > > a strange exception. Also, we've recently made RT_FIND return a\\n> > > pointer, so the caller must somehow hold a share lock, but I think we\\n> > > haven't exposed callers the ability to do that, and we rely on the tid\\n> > > store lock for that. We have a mix of tree locking and tid store\\n> > > locking. We will need to consider carefully how to make this more\\n> > > clear, maintainable, and understandable.\\n> >\\n> > Yes, tidstore should be locked during the iteration.\\n> >\\n> > One simple direction about locking is that the radix tree has the lock\\n> > but no APIs hold/release it. It's the caller's responsibility. If a\\n> > data structure using a radix tree for its storage has its own lock\\n> > (like tidstore), it can use it instead of the radix tree's one. A\\n>\\n> It looks like the only reason tidstore has its own lock is because it\\n> has no way to delegate locking to the tree's lock. Instead of working\\n> around the limitations of the thing we've designed, let's make it work\\n> for the one use case we have. I think we need to expose RT_LOCK_*\\n> functions to the outside, and have tid store use them. That would\\n> allow us to simplify all those \\\"if (TidStoreIsShared(ts)\\n> LWLockAcquire(..., ...)\\\" calls, which are complex and often redundant.\\n\\nI agree that we expose RT_LOCK_* functions and have tidstore use them,\\nbut am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\ncalls part. I think that even if we expose them, we will still need to\\ndo something like \\\"if (TidStoreIsShared(ts))\\nshared_rt_lock_share(ts->tree.shared)\\\", no?\\n\\n>\\n> At some point, we'll probably want to keep locking inside, at least to\\n> smooth the way for fine-grained locking you mentioned.\\n>\\n> > > In a green field, it'd be fine to replace these with an expression of\\n> > > \\\"num_offsets\\\", but it adds a bit of noise for reviewers and the git\\n> > > log. Is it really necessary?\\n> >\\n> > I see your point. I think we can live with having both\\n> > has_lpdead_items and num_offsets. But we will have to check if these\\n> > values are consistent, which could be less maintainable.\\n>\\n> It would be clearer if that removal was split out into a separate patch.\\n\\nAgreed.\\n\\n>\\n> > > I'm also not quite sure why \\\"deadoffsets\\\" and \\\"lpdead_items\\\" got\\n> > > moved to the PruneState. The latter was renamed in a way that makes\\n> > > more sense, but I don't see why the churn is necessary.\\n> ...\\n> > > I guess it was added here, 800 lines away? If so, why?\\n> >\\n> > The above changes are related. The idea is not to use tidstore in a\\n> > one-pass strategy. If the table doesn't have any indexes, in\\n> > lazy_scan_prune() we collect offset numbers of dead tuples on the page\\n> > and vacuum the page using them. In this case, we don't need to use\\n> > tidstore so we pass the offsets array to lazy_vacuum_heap_page(). The\\n> > LVPagePruneState is a convenient place to store collected offset\\n> > numbers.\\n>\\n> Okay, that makes sense, but if it was ever explained, I don't\\n> remember, and there is nothing in the commit message either.\\n>\\n> I'm not sure this can be split up easily, but if so it might help reviewing.\\n\\nAgreed.\\n\\n>\\n> This change also leads to a weird-looking control flow:\\n>\\n> if (vacrel->nindexes == 0)\\n> {\\n> if (prunestate.num_offsets > 0)\\n> {\\n> ...\\n> }\\n> }\\n> else if (prunestate.num_offsets > 0)\\n> {\\n> ...\\n> }\\n\\nFixed.\\n\\nI've attached a new patch set. From v47 patch, I've merged your\\nchanges for radix tree, and split the vacuum integration patch into 3\\npatches: simply replaces VacDeadItems with TidsTore (0007 patch), and\\nuse a simple TID array for one-pass strategy (0008 patch), and replace\\nhas_lpdead_items with \\\"num_offsets > 0\\\" (0009 patch), while\\nincorporating your review comments on the vacuum integration patch\\n(sorry for making it difficult to see the changes from v47 patch).\\n0013 to 0015 patches are also updates from v47 patch.\\n\\nI'm thinking that we should change the order of the patches so that\\ntidstore patch requires the patch for changing DSA segment sizes. That\\nway, we can remove the complex max memory calculation part that we no\\nlonger use from the tidstore patch.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 2 Jan 2024 22:01:07 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 2, 2024 at 8:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> I agree that we expose RT_LOCK_* functions and have tidstore use them,\\n> but am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\n> calls part. I think that even if we expose them, we will still need to\\n> do something like \\\"if (TidStoreIsShared(ts))\\n> shared_rt_lock_share(ts->tree.shared)\\\", no?\\n\\nI'll come back to this topic separately.\\n\\n> I've attached a new patch set. From v47 patch, I've merged your\\n> changes for radix tree, and split the vacuum integration patch into 3\\n> patches: simply replaces VacDeadItems with TidsTore (0007 patch), and\\n> use a simple TID array for one-pass strategy (0008 patch), and replace\\n> has_lpdead_items with \\\"num_offsets > 0\\\" (0009 patch), while\\n> incorporating your review comments on the vacuum integration patch\\n\\nNice!\\n\\n> (sorry for making it difficult to see the changes from v47 patch).\\n\\nIt's actually pretty clear. I just have a couple comments before\\nsharing my latest cleanups:\\n\\n(diff'ing between v47 and v48):\\n\\n-- /*\\n- * In the shared case, TidStoreControl and radix_tree are backed by the\\n- * same DSA area and rt_memory_usage() returns the value including both.\\n- * So we don't need to add the size of TidStoreControl separately.\\n- */\\n if (TidStoreIsShared(ts))\\n- return sizeof(TidStore) +\\nshared_rt_memory_usage(ts->tree.shared);\\n+ rt_mem = shared_rt_memory_usage(ts->tree.shared);\\n+ else\\n+ rt_mem = local_rt_memory_usage(ts->tree.local);\\n\\n- return sizeof(TidStore) + sizeof(TidStore) +\\nlocal_rt_memory_usage(ts->tree.local);\\n+ return sizeof(TidStore) + sizeof(TidStoreControl) + rt_mem;\\n\\nUpthread, I meant that I don't see the need to include the size of\\nthese structs *at all*. They're tiny, and the blocks/segments will\\nalmost certainly have some empty space counted in the total anyway.\\nThe returned size is already overestimated, so this extra code is just\\na distraction.\\n\\n- if (result->num_offsets + bmw_popcount(w) > result->max_offset)\\n+ if (result->num_offsets + (sizeof(bitmapword) * BITS_PER_BITMAPWORD)\\n>= result->max_offset)\\n\\nI believe this math is wrong. We care about \\\"result->num_offsets +\\nBITS_PER_BITMAPWORD\\\", right?\\nAlso, it seems if the condition evaluates to equal, we still have\\nenough space, in which case \\\">\\\" the max is the right condition.\\n\\n- if (off < 1 || off > MAX_TUPLES_PER_PAGE)\\n+ if (off < 1 || off > MaxOffsetNumber)\\n\\nThis can now use OffsetNumberIsValid().\\n\\n> 0013 to 0015 patches are also updates from v47 patch.\\n\\n> I'm thinking that we should change the order of the patches so that\\n> tidstore patch requires the patch for changing DSA segment sizes. That\\n> way, we can remove the complex max memory calculation part that we no\\n> longer use from the tidstore patch.\\n\\nI don't think there is any reason to have those calculations at all at\\nthis point. Every patch in every version should at least *work\\ncorrectly*, without kludging m_w_m and without constraining max\\nsegment size. I'm fine with the latter remaining in its own thread,\\nand I hope we can consider it an enhancement that respects the admin's\\nconfigured limits more effectively, and not a pre-requisite for not\\nbreaking. I *think* we're there now, but it's hard to tell since 0015\\nwas at the very end. As I said recently, if something still fails, I'd\\nlike to know why. So for v49, I took the liberty of removing the DSA\\nmax segment patches for now, and squashing v48-0015.\\n\\nIn addition for v49, I have quite a few cleanups:\\n\\n0001 - This hasn't been touched in a very long time, but I ran\\npgindent and clarified a comment\\n0002 - We no longer need to isolate the rightmost bit anywhere, so\\nremoved that part and revised the commit message accordingly.\\n\\nradix tree:\\n0003 - v48 plus squashed v48-0013\\n0004 - Removed or adjusted WIP, FIXME, TODO items. Some were outdated,\\nand I fixed most of the rest.\\n0005 - Remove the RT_PTR_LOCAL macro, since it's not really useful anymore.\\n0006 - RT_FREE_LEAF only needs the allocated pointer, so pass that. A\\nbit simpler.\\n0007 - Uses the same idea from a previous cleanup of RT_SET, for RT_DELETE.\\n0008 - Removes a holdover from the multi-value leaves era.\\n0009 - It occurred to me that we need to have unique names for memory\\ncontexts for different instantiations of the template. This is one way\\nto do it, by using the configured RT_PREFIX in the context name. I\\nalso took an extra step to make the size class fanout show up\\ncorrectly on different platforms, but that's probably overkill and\\nundesirable, and I'll probably use only the class name next time.\\n0010/11 - Make the array functions less surprising and with more\\ninformative names.\\n0012 - Restore a useful technique from Andres's prototype. This part\\nhas been slow for a long time, so much that it showed up in a profile\\nwhere this path wasn't even taken much.\\n\\ntid store / vacuum:\\n0013/14 - Same as v48 TID store, with review squashed\\n0015 - Rationalize comment and starting value.\\n0016 - I applied the removal of the old clamps from v48-0011 (init/max\\nDSA), and left out the rest for now.\\n0017-20 - Vacuum and debug tidstore as in v48, with v48-0015 squashed\\n\\nI'll bring up locking again shortly.\",\n \"msg_date\": \"Wed, 3 Jan 2024 21:10:11 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 3, 2024 at 9:10 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 2, 2024 at 8:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > I agree that we expose RT_LOCK_* functions and have tidstore use them,\\n> > but am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\n> > calls part. I think that even if we expose them, we will still need to\\n> > do something like \\\"if (TidStoreIsShared(ts))\\n> > shared_rt_lock_share(ts->tree.shared)\\\", no?\\n>\\n> I'll come back to this topic separately.\\n\\nTo answer your question, sure, but that \\\"if (TidStoreIsShared(ts))\\\"\\npart would be pushed down into a function so that only one place has\\nto care about it.\\n\\nHowever, I'm starting to question whether we even need that. Meaning,\\nlock the tidstore separately. To \\\"lock the tidstore\\\" means to take a\\nlock, _separate_ from the radix tree's internal lock, to control\\naccess to two fields in a separate \\\"control object\\\":\\n\\n+typedef struct TidStoreControl\\n+{\\n+ /* the number of tids in the store */\\n+ int64 num_tids;\\n+\\n+ /* the maximum bytes a TidStore can use */\\n+ size_t max_bytes;\\n\\nI'm pretty sure max_bytes does not need to be in shared memory, and\\ncertainly not under a lock: Thinking of a hypothetical\\nparallel-prune-phase scenario, one way would be for a leader process\\nto pass out ranges of blocks to workers, and when the limit is\\nexceeded, stop passing out blocks and wait for all the workers to\\nfinish.\\n\\nAs for num_tids, vacuum previously put the similar count in\\n\\n@@ -176,7 +179,8 @@ struct ParallelVacuumState\\n PVIndStats *indstats;\\n\\n /* Shared dead items space among parallel vacuum workers */\\n- VacDeadItems *dead_items;\\n+ TidStore *dead_items;\\n\\nVacDeadItems contained \\\"num_items\\\". What was the reason to have new\\ninfrastructure for that count? And it doesn't seem like access to it\\nwas controlled by a lock -- can you confirm? If we did get parallel\\npruning, maybe the count would belong inside PVShared?\\n\\nThe number of tids is not that tightly bound to the tidstore's job. I\\nbelieve tidbitmap.c (a possible future client) doesn't care about the\\nglobal number of tids -- not only that, but AND/OR operations can\\nchange the number in a non-obvious way, so it would not be convenient\\nto keep an accurate number anyway. But the lock would still be\\nmandatory with this patch.\\n\\nIf we can make vacuum work a bit closer to how it does now, it'd be a\\nbig step up in readability, I think. Namely, getting rid of all the\\nlocking logic inside tidstore.c and let the radix tree's locking do\\nthe right thing. We'd need to make that work correctly when receiving\\npointers to values upon lookup, and I already shared ideas for that.\\nBut I want to see if there is any obstacle in the way of removing the\\ntidstore control object and it's separate lock.\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Jan 2024 18:35:22 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 3, 2024 at 11:10 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 2, 2024 at 8:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > I agree that we expose RT_LOCK_* functions and have tidstore use them,\\n> > but am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\n> > calls part. I think that even if we expose them, we will still need to\\n> > do something like \\\"if (TidStoreIsShared(ts))\\n> > shared_rt_lock_share(ts->tree.shared)\\\", no?\\n>\\n> I'll come back to this topic separately.\\n>\\n> > I've attached a new patch set. From v47 patch, I've merged your\\n> > changes for radix tree, and split the vacuum integration patch into 3\\n> > patches: simply replaces VacDeadItems with TidsTore (0007 patch), and\\n> > use a simple TID array for one-pass strategy (0008 patch), and replace\\n> > has_lpdead_items with \\\"num_offsets > 0\\\" (0009 patch), while\\n> > incorporating your review comments on the vacuum integration patch\\n>\\n> Nice!\\n>\\n> > (sorry for making it difficult to see the changes from v47 patch).\\n>\\n> It's actually pretty clear. I just have a couple comments before\\n> sharing my latest cleanups:\\n>\\n> (diff'ing between v47 and v48):\\n>\\n> -- /*\\n> - * In the shared case, TidStoreControl and radix_tree are backed by the\\n> - * same DSA area and rt_memory_usage() returns the value including both.\\n> - * So we don't need to add the size of TidStoreControl separately.\\n> - */\\n> if (TidStoreIsShared(ts))\\n> - return sizeof(TidStore) +\\n> shared_rt_memory_usage(ts->tree.shared);\\n> + rt_mem = shared_rt_memory_usage(ts->tree.shared);\\n> + else\\n> + rt_mem = local_rt_memory_usage(ts->tree.local);\\n>\\n> - return sizeof(TidStore) + sizeof(TidStore) +\\n> local_rt_memory_usage(ts->tree.local);\\n> + return sizeof(TidStore) + sizeof(TidStoreControl) + rt_mem;\\n>\\n> Upthread, I meant that I don't see the need to include the size of\\n> these structs *at all*. They're tiny, and the blocks/segments will\\n> almost certainly have some empty space counted in the total anyway.\\n> The returned size is already overestimated, so this extra code is just\\n> a distraction.\\n\\nAgreed.\\n\\n>\\n> - if (result->num_offsets + bmw_popcount(w) > result->max_offset)\\n> + if (result->num_offsets + (sizeof(bitmapword) * BITS_PER_BITMAPWORD)\\n> >= result->max_offset)\\n>\\n> I believe this math is wrong. We care about \\\"result->num_offsets +\\n> BITS_PER_BITMAPWORD\\\", right?\\n> Also, it seems if the condition evaluates to equal, we still have\\n> enough space, in which case \\\">\\\" the max is the right condition.\\n\\nOops, you're right. Fixed.\\n\\n>\\n> - if (off < 1 || off > MAX_TUPLES_PER_PAGE)\\n> + if (off < 1 || off > MaxOffsetNumber)\\n>\\n> This can now use OffsetNumberIsValid().\\n\\nFixed.\\n\\n>\\n> > 0013 to 0015 patches are also updates from v47 patch.\\n>\\n> > I'm thinking that we should change the order of the patches so that\\n> > tidstore patch requires the patch for changing DSA segment sizes. That\\n> > way, we can remove the complex max memory calculation part that we no\\n> > longer use from the tidstore patch.\\n>\\n> I don't think there is any reason to have those calculations at all at\\n> this point. Every patch in every version should at least *work\\n> correctly*, without kludging m_w_m and without constraining max\\n> segment size. I'm fine with the latter remaining in its own thread,\\n> and I hope we can consider it an enhancement that respects the admin's\\n> configured limits more effectively, and not a pre-requisite for not\\n> breaking. I *think* we're there now, but it's hard to tell since 0015\\n> was at the very end. As I said recently, if something still fails, I'd\\n> like to know why. So for v49, I took the liberty of removing the DSA\\n> max segment patches for now, and squashing v48-0015.\\n\\nFair enough.\\n\\n>\\n> In addition for v49, I have quite a few cleanups:\\n>\\n> 0001 - This hasn't been touched in a very long time, but I ran\\n> pgindent and clarified a comment\\n> 0002 - We no longer need to isolate the rightmost bit anywhere, so\\n> removed that part and revised the commit message accordingly.\\n\\nThanks.\\n\\n>\\n> radix tree:\\n> 0003 - v48 plus squashed v48-0013\\n> 0004 - Removed or adjusted WIP, FIXME, TODO items. Some were outdated,\\n> and I fixed most of the rest.\\n> 0005 - Remove the RT_PTR_LOCAL macro, since it's not really useful anymore.\\n> 0006 - RT_FREE_LEAF only needs the allocated pointer, so pass that. A\\n> bit simpler.\\n> 0007 - Uses the same idea from a previous cleanup of RT_SET, for RT_DELETE.\\n> 0008 - Removes a holdover from the multi-value leaves era.\\n> 0009 - It occurred to me that we need to have unique names for memory\\n> contexts for different instantiations of the template. This is one way\\n> to do it, by using the configured RT_PREFIX in the context name. I\\n> also took an extra step to make the size class fanout show up\\n> correctly on different platforms, but that's probably overkill and\\n> undesirable, and I'll probably use only the class name next time.\\n> 0010/11 - Make the array functions less surprising and with more\\n> informative names.\\n> 0012 - Restore a useful technique from Andres's prototype. This part\\n> has been slow for a long time, so much that it showed up in a profile\\n> where this path wasn't even taken much.\\n\\nThese changes look good to me. I've squashed them.\\n\\nIn addition, I've made some changes and cleanups:\\n\\n0010 - address the above review comments.\\n0011 - simplify the radix tree iteration code. I hope it makes the\\ncode clear and readable. Also I removed RT_UPDATE_ITER_STACK().\\n0012 - fix a typo\\n0013 - In RT_SHMEM case, we use SIZEOF_VOID_P for\\nRT_VALUE_IS_EMBEDDABLE check, but I think it's not correct. Because\\nDSA has its own pointer size, SIZEOF_DSA_POINTER, it could be 4 bytes\\neven if SIZEOF_VOID_P is 8 bytes, for example in a case where\\n!defined(PG_HAVE_ATOMIC_U64_SUPPORT). Please refer to dsa.h for\\ndetails.\\n0014 - cleanup RT_VERIFY code.\\n0015 - change and cleanup RT_DUMP_NODE(). Now it dumps only one node\\nand no longer supports dumping nodes recursively.\\n0016 - remove RT_DUMP_SEARCH() and RT_DUMP(). These seem no longer necessary.\\n0017 - MOve RT_DUMP_NODE to the debug function section, close to RT_STATS.\\n0018 - Fix a printf format in RT_STATS().\\n\\nBTW, now that the inner and leaf nodes use the same structure, do we\\nstill need RT_NODE_BASE_XXX types? Most places where we use\\nRT_NODE_BASE_XXX types can be replaced with RT_NODE_XXX types.\\nExceptions are RT_FANOUT_XX calculations:\\n\\n#if SIZEOF_VOID_P < 8\\n#define RT_FANOUT_16_LO ((96 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n#define RT_FANOUT_48 ((512 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n#else\\n#define RT_FANOUT_16_LO ((160 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n#define RT_FANOUT_48 ((768 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n#endif /* SIZEOF_VOID_P < 8 */\\n\\nBut I think we can replace them with offsetof(RT_NODE_16, children) etc.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 9 Jan 2024 11:40:03 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 9, 2024 at 9:40 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> In addition, I've made some changes and cleanups:\\n\\nThese look good to me, although I have not tried dumping a node in a while.\\n\\n> 0011 - simplify the radix tree iteration code. I hope it makes the\\n> code clear and readable. Also I removed RT_UPDATE_ITER_STACK().\\n\\nI'm very pleased with how much simpler it is now!\\n\\n> 0013 - In RT_SHMEM case, we use SIZEOF_VOID_P for\\n> RT_VALUE_IS_EMBEDDABLE check, but I think it's not correct. Because\\n> DSA has its own pointer size, SIZEOF_DSA_POINTER, it could be 4 bytes\\n> even if SIZEOF_VOID_P is 8 bytes, for example in a case where\\n> !defined(PG_HAVE_ATOMIC_U64_SUPPORT). Please refer to dsa.h for\\n> details.\\n\\nThanks for the pointer. ;-)\\n\\n> BTW, now that the inner and leaf nodes use the same structure, do we\\n> still need RT_NODE_BASE_XXX types? Most places where we use\\n> RT_NODE_BASE_XXX types can be replaced with RT_NODE_XXX types.\\n\\nThat's been in the back of my mind as well. Maybe the common header\\nshould be the new \\\"base\\\" member? At least, something other than \\\"n\\\".\\n\\n> Exceptions are RT_FANOUT_XX calculations:\\n>\\n> #if SIZEOF_VOID_P < 8\\n> #define RT_FANOUT_16_LO ((96 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n> #define RT_FANOUT_48 ((512 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n> #else\\n> #define RT_FANOUT_16_LO ((160 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n> #define RT_FANOUT_48 ((768 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n> #endif /* SIZEOF_VOID_P < 8 */\\n>\\n> But I think we can replace them with offsetof(RT_NODE_16, children) etc.\\n\\nThat makes sense. Do you want to have a go at it, or shall I?\\n\\nI think after that, the only big cleanup needed is putting things in a\\nmore readable order. I can do that at a later date, and other\\nopportunities for beautification are pretty minor and localized.\\n\\nRationalizing locking is the only thing left that requires a bit of thought.\\n\\n\\n\",\n \"msg_date\": \"Tue, 9 Jan 2024 18:19:46 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 9, 2024 at 8:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 9, 2024 at 9:40 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > In addition, I've made some changes and cleanups:\\n>\\n> These look good to me, although I have not tried dumping a node in a while.\\n>\\n> > 0011 - simplify the radix tree iteration code. I hope it makes the\\n> > code clear and readable. Also I removed RT_UPDATE_ITER_STACK().\\n>\\n> I'm very pleased with how much simpler it is now!\\n>\\n> > 0013 - In RT_SHMEM case, we use SIZEOF_VOID_P for\\n> > RT_VALUE_IS_EMBEDDABLE check, but I think it's not correct. Because\\n> > DSA has its own pointer size, SIZEOF_DSA_POINTER, it could be 4 bytes\\n> > even if SIZEOF_VOID_P is 8 bytes, for example in a case where\\n> > !defined(PG_HAVE_ATOMIC_U64_SUPPORT). Please refer to dsa.h for\\n> > details.\\n>\\n> Thanks for the pointer. ;-)\\n>\\n> > BTW, now that the inner and leaf nodes use the same structure, do we\\n> > still need RT_NODE_BASE_XXX types? Most places where we use\\n> > RT_NODE_BASE_XXX types can be replaced with RT_NODE_XXX types.\\n>\\n> That's been in the back of my mind as well. Maybe the common header\\n> should be the new \\\"base\\\" member? At least, something other than \\\"n\\\".\\n\\nAgreed.\\n\\n>\\n> > Exceptions are RT_FANOUT_XX calculations:\\n> >\\n> > #if SIZEOF_VOID_P < 8\\n> > #define RT_FANOUT_16_LO ((96 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n> > #define RT_FANOUT_48 ((512 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n> > #else\\n> > #define RT_FANOUT_16_LO ((160 - sizeof(RT_NODE_BASE_16)) / sizeof(RT_PTR_ALLOC))\\n> > #define RT_FANOUT_48 ((768 - sizeof(RT_NODE_BASE_48)) / sizeof(RT_PTR_ALLOC))\\n> > #endif /* SIZEOF_VOID_P < 8 */\\n> >\\n> > But I think we can replace them with offsetof(RT_NODE_16, children) etc.\\n>\\n> That makes sense. Do you want to have a go at it, or shall I?\\n\\nI've done in 0010 patch in v51 patch set. Whereas RT_NODE_4 and\\nRT_NODE_16 structs declaration needs RT_FANOUT_4_HI and\\nRT_FANOUT_16_HI respectively, RT_FANOUT_16_LO and RT_FANOUT_48 need\\nRT_NODE_16 and RT_NODE_48 structs declaration. So fanout declarations\\nare now spread before and after RT_NODE_XXX struct declaration. It's a\\nbit less readable, but I'm not sure of a better way.\\n\\nThe previous updates are merged into the main radix tree patch and\\ntidstore patch. Nothing changes in other patches from v50.\\n\\n>\\n> I think after that, the only big cleanup needed is putting things in a\\n> more readable order. I can do that at a later date, and other\\n> opportunities for beautification are pretty minor and localized.\\n\\nAgreed.\\n\\n>\\n> Rationalizing locking is the only thing left that requires a bit of thought.\\n\\nRight, I'll send a reply soon.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 10 Jan 2024 11:05:06 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 10, 2024 at 9:05 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I've done in 0010 patch in v51 patch set. Whereas RT_NODE_4 and\\n> RT_NODE_16 structs declaration needs RT_FANOUT_4_HI and\\n> RT_FANOUT_16_HI respectively, RT_FANOUT_16_LO and RT_FANOUT_48 need\\n> RT_NODE_16 and RT_NODE_48 structs declaration. So fanout declarations\\n> are now spread before and after RT_NODE_XXX struct declaration. It's a\\n> bit less readable, but I'm not sure of a better way.\\n\\nThey were before and after the *_BASE types, so it's not really worse,\\nI think. I did notice that RT_SLOT_IDX_LIMIT has been considered\\nspecial for a very long time, before we even had size classes, so it's\\nthe same thing but even more far away. I have an idea to introduce\\n*_MAX macros, allowing to turn RT_SLOT_IDX_LIMIT into\\nRT_FANOUT_48_MAX, so that everything is in the same spot, and to make\\nthis area more consistent. I also noticed that I'd been assuming that\\nRT_FANOUT_16_HI fits easily into a DSA size class, but that's only\\ntrue on 64-bit, and in any case we don't want to assume it. I've\\nattached an addendum .txt to demo this idea.\",\n \"msg_date\": \"Wed, 10 Jan 2024 13:40:40 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 8, 2024 at 8:35 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Jan 3, 2024 at 9:10 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Tue, Jan 2, 2024 at 8:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > I agree that we expose RT_LOCK_* functions and have tidstore use them,\\n> > > but am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\n> > > calls part. I think that even if we expose them, we will still need to\\n> > > do something like \\\"if (TidStoreIsShared(ts))\\n> > > shared_rt_lock_share(ts->tree.shared)\\\", no?\\n> >\\n> > I'll come back to this topic separately.\\n>\\n> To answer your question, sure, but that \\\"if (TidStoreIsShared(ts))\\\"\\n> part would be pushed down into a function so that only one place has\\n> to care about it.\\n>\\n> However, I'm starting to question whether we even need that. Meaning,\\n> lock the tidstore separately. To \\\"lock the tidstore\\\" means to take a\\n> lock, _separate_ from the radix tree's internal lock, to control\\n> access to two fields in a separate \\\"control object\\\":\\n>\\n> +typedef struct TidStoreControl\\n> +{\\n> + /* the number of tids in the store */\\n> + int64 num_tids;\\n> +\\n> + /* the maximum bytes a TidStore can use */\\n> + size_t max_bytes;\\n>\\n> I'm pretty sure max_bytes does not need to be in shared memory, and\\n> certainly not under a lock: Thinking of a hypothetical\\n> parallel-prune-phase scenario, one way would be for a leader process\\n> to pass out ranges of blocks to workers, and when the limit is\\n> exceeded, stop passing out blocks and wait for all the workers to\\n> finish.\\n\\nTrue. I agreed that it doesn't need to be under a lock anyway, as it's\\nread-only.\\n\\n>\\n> As for num_tids, vacuum previously put the similar count in\\n>\\n> @@ -176,7 +179,8 @@ struct ParallelVacuumState\\n> PVIndStats *indstats;\\n>\\n> /* Shared dead items space among parallel vacuum workers */\\n> - VacDeadItems *dead_items;\\n> + TidStore *dead_items;\\n>\\n> VacDeadItems contained \\\"num_items\\\". What was the reason to have new\\n> infrastructure for that count? And it doesn't seem like access to it\\n> was controlled by a lock -- can you confirm? If we did get parallel\\n> pruning, maybe the count would belong inside PVShared?\\n\\nI thought that since the tidstore is a general-purpose data structure\\nthe shared counter should be protected by a lock. One thing I'm\\nconcerned about is that we might need to update both the radix tree\\nand the counter atomically in some cases. But that's true we don't\\nneed it for lazy vacuum at least for now. Even given the parallel scan\\nphase, probably we won't need to have workers check the total number\\nof stored tuples during a parallel scan.\\n\\n>\\n> The number of tids is not that tightly bound to the tidstore's job. I\\n> believe tidbitmap.c (a possible future client) doesn't care about the\\n> global number of tids -- not only that, but AND/OR operations can\\n> change the number in a non-obvious way, so it would not be convenient\\n> to keep an accurate number anyway. But the lock would still be\\n> mandatory with this patch.\\n\\nVery good point.\\n\\n>\\n> If we can make vacuum work a bit closer to how it does now, it'd be a\\n> big step up in readability, I think. Namely, getting rid of all the\\n> locking logic inside tidstore.c and let the radix tree's locking do\\n> the right thing. We'd need to make that work correctly when receiving\\n> pointers to values upon lookup, and I already shared ideas for that.\\n> But I want to see if there is any obstacle in the way of removing the\\n> tidstore control object and it's separate lock.\\n\\nSo I agree to remove both max_bytes and num_items from the control\\nobject.Also, as you mentioned, we can remove the tidstore control\\nobject itself. TidStoreGetHandle() returns a radix tree handle, and we\\ncan pass it to TidStoreAttach(). I'll try it.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 11 Jan 2024 09:28:44 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 11, 2024 at 9:28 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Jan 8, 2024 at 8:35 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Wed, Jan 3, 2024 at 9:10 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Tue, Jan 2, 2024 at 8:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > I agree that we expose RT_LOCK_* functions and have tidstore use them,\\n> > > > but am not sure the if (TidStoreIsShared(ts) LWLockAcquire(..., ...)\\\"\\n> > > > calls part. I think that even if we expose them, we will still need to\\n> > > > do something like \\\"if (TidStoreIsShared(ts))\\n> > > > shared_rt_lock_share(ts->tree.shared)\\\", no?\\n> > >\\n> > > I'll come back to this topic separately.\\n> >\\n> > To answer your question, sure, but that \\\"if (TidStoreIsShared(ts))\\\"\\n> > part would be pushed down into a function so that only one place has\\n> > to care about it.\\n> >\\n> > However, I'm starting to question whether we even need that. Meaning,\\n> > lock the tidstore separately. To \\\"lock the tidstore\\\" means to take a\\n> > lock, _separate_ from the radix tree's internal lock, to control\\n> > access to two fields in a separate \\\"control object\\\":\\n> >\\n> > +typedef struct TidStoreControl\\n> > +{\\n> > + /* the number of tids in the store */\\n> > + int64 num_tids;\\n> > +\\n> > + /* the maximum bytes a TidStore can use */\\n> > + size_t max_bytes;\\n> >\\n> > I'm pretty sure max_bytes does not need to be in shared memory, and\\n> > certainly not under a lock: Thinking of a hypothetical\\n> > parallel-prune-phase scenario, one way would be for a leader process\\n> > to pass out ranges of blocks to workers, and when the limit is\\n> > exceeded, stop passing out blocks and wait for all the workers to\\n> > finish.\\n>\\n> True. I agreed that it doesn't need to be under a lock anyway, as it's\\n> read-only.\\n>\\n> >\\n> > As for num_tids, vacuum previously put the similar count in\\n> >\\n> > @@ -176,7 +179,8 @@ struct ParallelVacuumState\\n> > PVIndStats *indstats;\\n> >\\n> > /* Shared dead items space among parallel vacuum workers */\\n> > - VacDeadItems *dead_items;\\n> > + TidStore *dead_items;\\n> >\\n> > VacDeadItems contained \\\"num_items\\\". What was the reason to have new\\n> > infrastructure for that count? And it doesn't seem like access to it\\n> > was controlled by a lock -- can you confirm? If we did get parallel\\n> > pruning, maybe the count would belong inside PVShared?\\n>\\n> I thought that since the tidstore is a general-purpose data structure\\n> the shared counter should be protected by a lock. One thing I'm\\n> concerned about is that we might need to update both the radix tree\\n> and the counter atomically in some cases. But that's true we don't\\n> need it for lazy vacuum at least for now. Even given the parallel scan\\n> phase, probably we won't need to have workers check the total number\\n> of stored tuples during a parallel scan.\\n>\\n> >\\n> > The number of tids is not that tightly bound to the tidstore's job. I\\n> > believe tidbitmap.c (a possible future client) doesn't care about the\\n> > global number of tids -- not only that, but AND/OR operations can\\n> > change the number in a non-obvious way, so it would not be convenient\\n> > to keep an accurate number anyway. But the lock would still be\\n> > mandatory with this patch.\\n>\\n> Very good point.\\n>\\n> >\\n> > If we can make vacuum work a bit closer to how it does now, it'd be a\\n> > big step up in readability, I think. Namely, getting rid of all the\\n> > locking logic inside tidstore.c and let the radix tree's locking do\\n> > the right thing. We'd need to make that work correctly when receiving\\n> > pointers to values upon lookup, and I already shared ideas for that.\\n> > But I want to see if there is any obstacle in the way of removing the\\n> > tidstore control object and it's separate lock.\\n>\\n> So I agree to remove both max_bytes and num_items from the control\\n> object.Also, as you mentioned, we can remove the tidstore control\\n> object itself. TidStoreGetHandle() returns a radix tree handle, and we\\n> can pass it to TidStoreAttach(). I'll try it.\\n>\\n\\nI realized that if we remove the whole tidstore control object\\nincluding max_bytes, processes who attached the shared tidstore cannot\\nuse TidStoreIsFull() actually as it always returns true. Also they\\ncannot use TidStoreReset() as well since it needs to pass max_bytes to\\nRT_CREATE(). It might not be a problem in terms of lazy vacuum, but it\\ncould be problematic for general use. If we remove it, we probably\\nneed a safeguard to prevent those who attached the tidstore from\\ncalling these functions. Or we can keep the control object but remove\\nthe lock and num_tids.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 12 Jan 2024 17:49:04 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 12, 2024 at 3:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Jan 11, 2024 at 9:28 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > So I agree to remove both max_bytes and num_items from the control\\n> > object.Also, as you mentioned, we can remove the tidstore control\\n> > object itself. TidStoreGetHandle() returns a radix tree handle, and we\\n> > can pass it to TidStoreAttach(). I'll try it.\\n\\nThanks. It's worth looking closely here.\\n\\n> I realized that if we remove the whole tidstore control object\\n> including max_bytes, processes who attached the shared tidstore cannot\\n> use TidStoreIsFull() actually as it always returns true.\\n\\nI imagine that we'd replace that with a function (maybe an earlier\\nversion had it?) to report the memory usage to the caller, which\\nshould know where to find max_bytes.\\n\\n> Also they\\n> cannot use TidStoreReset() as well since it needs to pass max_bytes to\\n> RT_CREATE(). It might not be a problem in terms of lazy vacuum, but it\\n> could be problematic for general use.\\n\\nHEAD has no problem finding the necessary values, and I don't think\\nit'd be difficult to maintain that ability. I'm not actually sure what\\n\\\"general use\\\" needs to have, and I'm not sure anyone can guess.\\nThere's the future possibility of parallel heap-scanning, but I'm\\nguessing a *lot* more needs to happen for that to work, so I'm not\\nsure how much it buys us to immediately start putting those two fields\\nin a special abstraction. The only other concrete use case mentioned\\nin this thread that I remember is bitmap heap scan, and I believe that\\nwould never need to reset, only free the whole thing when finished.\\n\\nI spent some more time studying parallel vacuum, and have some\\nthoughts. In HEAD, we have\\n\\n-/*\\n- * VacDeadItems stores TIDs whose index tuples are deleted by index vacuuming.\\n- */\\n-typedef struct VacDeadItems\\n-{\\n- int max_items; /* # slots allocated in array */\\n- int num_items; /* current # of entries */\\n-\\n- /* Sorted array of TIDs to delete from indexes */\\n- ItemPointerData items[FLEXIBLE_ARRAY_MEMBER];\\n-} VacDeadItems;\\n\\n...which has the tids, plus two fields that function _very similarly_\\nto the two extra fields in the tidstore control object. It's a bit\\nstrange to me that the patch doesn't have this struct anymore.\\n\\nI suspect if we keep it around (just change \\\"items\\\" to be the local\\ntidstore struct), the patch would have a bit less churn and look/work\\nmore like the current code. I think it might be easier to read if the\\nv17 commits are suited to the current needs of vacuum, rather than try\\nto anticipate all uses. Richer abstractions can come later if needed.\\nAnother stanza:\\n\\n- /* Prepare the dead_items space */\\n- dead_items = (VacDeadItems *) shm_toc_allocate(pcxt->toc,\\n- est_dead_items_len);\\n- dead_items->max_items = max_items;\\n- dead_items->num_items = 0;\\n- MemSet(dead_items->items, 0, sizeof(ItemPointerData) * max_items);\\n- shm_toc_insert(pcxt->toc, PARALLEL_VACUUM_KEY_DEAD_ITEMS, dead_items);\\n- pvs->dead_items = dead_items;\\n\\nWith s/max_items/max_bytes/, I wonder if we can still use some of\\nthis, and parallel workers would have no problem getting the necessary\\ninfo, as they do today. If not, I don't really understand why. I'm not\\nvery familiar with working with shared memory, and I know the tree\\nitself needs some different setup, so it's quite possible I'm missing\\nsomething.\\n\\nI find it difficult to kept straight these four things:\\n\\n- radix tree\\n- radix tree control object\\n- tidstore\\n- tidstore control object\\n\\nEven with the code in front of me, it's hard to reason about how these\\nconcepts fit together. It'd be much more readable if this was\\nsimplified.\\n\\n\\n\",\n \"msg_date\": \"Sun, 14 Jan 2024 20:42:49 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Jan 14, 2024 at 10:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Jan 12, 2024 at 3:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Jan 11, 2024 at 9:28 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > So I agree to remove both max_bytes and num_items from the control\\n> > > object.Also, as you mentioned, we can remove the tidstore control\\n> > > object itself. TidStoreGetHandle() returns a radix tree handle, and we\\n> > > can pass it to TidStoreAttach(). I'll try it.\\n>\\n> Thanks. It's worth looking closely here.\\n>\\n> > I realized that if we remove the whole tidstore control object\\n> > including max_bytes, processes who attached the shared tidstore cannot\\n> > use TidStoreIsFull() actually as it always returns true.\\n>\\n> I imagine that we'd replace that with a function (maybe an earlier\\n> version had it?) to report the memory usage to the caller, which\\n> should know where to find max_bytes.\\n>\\n> > Also they\\n> > cannot use TidStoreReset() as well since it needs to pass max_bytes to\\n> > RT_CREATE(). It might not be a problem in terms of lazy vacuum, but it\\n> > could be problematic for general use.\\n>\\n> HEAD has no problem finding the necessary values, and I don't think\\n> it'd be difficult to maintain that ability. I'm not actually sure what\\n> \\\"general use\\\" needs to have, and I'm not sure anyone can guess.\\n> There's the future possibility of parallel heap-scanning, but I'm\\n> guessing a *lot* more needs to happen for that to work, so I'm not\\n> sure how much it buys us to immediately start putting those two fields\\n> in a special abstraction. The only other concrete use case mentioned\\n> in this thread that I remember is bitmap heap scan, and I believe that\\n> would never need to reset, only free the whole thing when finished.\\n>\\n> I spent some more time studying parallel vacuum, and have some\\n> thoughts. In HEAD, we have\\n>\\n> -/*\\n> - * VacDeadItems stores TIDs whose index tuples are deleted by index vacuuming.\\n> - */\\n> -typedef struct VacDeadItems\\n> -{\\n> - int max_items; /* # slots allocated in array */\\n> - int num_items; /* current # of entries */\\n> -\\n> - /* Sorted array of TIDs to delete from indexes */\\n> - ItemPointerData items[FLEXIBLE_ARRAY_MEMBER];\\n> -} VacDeadItems;\\n>\\n> ...which has the tids, plus two fields that function _very similarly_\\n> to the two extra fields in the tidstore control object. It's a bit\\n> strange to me that the patch doesn't have this struct anymore.\\n>\\n> I suspect if we keep it around (just change \\\"items\\\" to be the local\\n> tidstore struct), the patch would have a bit less churn and look/work\\n> more like the current code. I think it might be easier to read if the\\n> v17 commits are suited to the current needs of vacuum, rather than try\\n> to anticipate all uses. Richer abstractions can come later if needed.\\n\\nJust changing \\\"items\\\" to be the local tidstore struct could make the\\ncode tricky a bit, since max_bytes and num_items are on the shared\\nmemory while \\\"items\\\" is a local pointer to the shared tidstore. This\\nis a reason why I abstract them behind TidStore. However, IIUC the\\ncurrent parallel vacuum can work with such VacDeadItems fields,\\nfortunately. The leader process can use VacDeadItems allocated on DSM,\\nand worker processes can use a local VacDeadItems of which max_bytes\\nand num_items are copied from the shared one and \\\"items\\\" is a local\\npointer.\\n\\nAssuming parallel heap scan requires for both the leader and workers\\nto update the shared VacDeadItems concurrently, we may need such\\nricher abstractions.\\n\\nI've implemented this idea in the v52 patch set. Here is the summary\\nof the updates:\\n\\n0008: Remove the control object from tidstore. Also removed some\\nunsupported functions such as TidStoreNumTids()\\n0009: Adjust lazy vacuum integration patch with the control object removal.\\n\\nI've not updated any locking code yet. Once we confirm this direction,\\nI'll update the locking code too.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 16 Jan 2024 15:17:35 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 16, 2024 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> Just changing \\\"items\\\" to be the local tidstore struct could make the\\n> code tricky a bit, since max_bytes and num_items are on the shared\\n> memory while \\\"items\\\" is a local pointer to the shared tidstore.\\n\\nThanks for trying it this way! I like the overall simplification but\\nthis aspect is not great.\\nHmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\ntheir own allocations and returning a pointer. Would it be less tricky\\nif the structs were declared where we need them and passed to \\\"init\\\"\\nfunctions?\\n\\nThat may be a good idea for other reasons. It's awkward that the\\ncreate function is declared like this:\\n\\n#ifdef RT_SHMEM\\nRT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes,\\ndsa_area *dsa,\\nint tranche_id);\\n#else\\nRT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes);\\n#endif\\n\\nAn init function wouldn't need these parameters: it could look at the\\npassed struct to know what to do.\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Jan 2024 07:20:21 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 17, 2024 at 9:20 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 16, 2024 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > Just changing \\\"items\\\" to be the local tidstore struct could make the\\n> > code tricky a bit, since max_bytes and num_items are on the shared\\n> > memory while \\\"items\\\" is a local pointer to the shared tidstore.\\n>\\n> Thanks for trying it this way! I like the overall simplification but\\n> this aspect is not great.\\n> Hmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\n> their own allocations and returning a pointer. Would it be less tricky\\n> if the structs were declared where we need them and passed to \\\"init\\\"\\n> functions?\\n\\nSeems worth trying. The current RT_CREATE() API is also convenient as\\nother data structure such as simplehash.h and dshash.c supports a\\nsimilar\\n\\n>\\n> That may be a good idea for other reasons. It's awkward that the\\n> create function is declared like this:\\n>\\n> #ifdef RT_SHMEM\\n> RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes,\\n> dsa_area *dsa,\\n> int tranche_id);\\n> #else\\n> RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes);\\n> #endif\\n>\\n> An init function wouldn't need these parameters: it could look at the\\n> passed struct to know what to do.\\n\\nBut the init function would initialize leaf_ctx etc,no? Initializing\\nleaf_ctx needs max_bytes that is not stored in RT_RADIX_TREE. The same\\nis true for dsa. I imagined that an init function would allocate a DSA\\nmemory for the control object. So I imagine we will end up still\\nrequiring some of them.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Jan 2024 10:38:47 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 17, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Jan 17, 2024 at 9:20 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Tue, Jan 16, 2024 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > Just changing \\\"items\\\" to be the local tidstore struct could make the\\n> > > code tricky a bit, since max_bytes and num_items are on the shared\\n> > > memory while \\\"items\\\" is a local pointer to the shared tidstore.\\n> >\\n> > Thanks for trying it this way! I like the overall simplification but\\n> > this aspect is not great.\\n> > Hmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\n> > their own allocations and returning a pointer. Would it be less tricky\\n> > if the structs were declared where we need them and passed to \\\"init\\\"\\n> > functions?\\n>\\n> Seems worth trying. The current RT_CREATE() API is also convenient as\\n> other data structure such as simplehash.h and dshash.c supports a\\n> similar\\n\\nI don't happen to know if these paths had to solve similar trickiness\\nwith some values being local, and some shared.\\n\\n> > That may be a good idea for other reasons. It's awkward that the\\n> > create function is declared like this:\\n> >\\n> > #ifdef RT_SHMEM\\n> > RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes,\\n> > dsa_area *dsa,\\n> > int tranche_id);\\n> > #else\\n> > RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes);\\n> > #endif\\n> >\\n> > An init function wouldn't need these parameters: it could look at the\\n> > passed struct to know what to do.\\n>\\n> But the init function would initialize leaf_ctx etc,no? Initializing\\n> leaf_ctx needs max_bytes that is not stored in RT_RADIX_TREE.\\n\\nI was more referring to the parameters that were different above\\ndepending on shared memory. My first thought was that the tricky part\\nis because of the allocation in local memory, but it's certainly\\npossible I've misunderstood the problem.\\n\\n> The same\\n> is true for dsa. I imagined that an init function would allocate a DSA\\n> memory for the control object.\\n\\nYes:\\n\\n...\\n// embedded in VacDeadItems\\n TidStore items;\\n};\\n\\n// NULL DSA in local case, etc\\ndead_items->items.area = dead_items_dsa;\\ndead_items->items.tranche_id = FOO_ID;\\n\\nTidStoreInit(&dead_items->items, vac_work_mem);\\n\\nThat's how I imagined it would work (leaving out some details). I\\nhaven't tried it, so not sure how much it helps. Maybe it has other\\nproblems, but I'm hoping it's just a matter of programming.\\n\\nIf we can't make this work nicely, I'd be okay with keeping the tid\\nstore control object. My biggest concern is unnecessary\\ndouble-locking.\\n\\n\\n\",\n \"msg_date\": \"Wed, 17 Jan 2024 09:37:18 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n\\n> > Hmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\n> > their own allocations and returning a pointer. Would it be less tricky\\n> > if the structs were declared where we need them and passed to \\\"init\\\"\\n> > functions?\\n\\nIf this is a possibility, I thought I'd first send the last (I hope)\\nlarge-ish set of radix tree cleanups to avoid rebasing issues. I'm not\\nincluding tidstore/vacuum here, because recent discussion has some\\nup-in-the-air work.\\n\\nShould be self-explanatory, but some thing are worth calling out:\\n0012 and 0013: Some time ago I started passing insertpos as a\\nparameter, but now see that is not ideal -- when growing from node16\\nto node48 we don't need it at all, so it's a wasted calculation. While\\nreverting that, I found that this also allows passing constants in\\nsome cases.\\n0014 makes a cleaner separation between adding a child and growing a\\nnode, resulting in more compact-looking functions.\\n0019 is a bit unpolished, but I realized that it's pointless to assign\\na zero child when further up the call stack we overwrite it anyway\\nwith the actual value. With this, that assignment is skipped. This\\nmakes some comments and names strange, so needs a bit of polish, but\\nwanted to get it out there anyway.\",\n \"msg_date\": \"Wed, 17 Jan 2024 10:32:25 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 17, 2024 at 11:37 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Jan 17, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Wed, Jan 17, 2024 at 9:20 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Tue, Jan 16, 2024 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > > Just changing \\\"items\\\" to be the local tidstore struct could make the\\n> > > > code tricky a bit, since max_bytes and num_items are on the shared\\n> > > > memory while \\\"items\\\" is a local pointer to the shared tidstore.\\n> > >\\n> > > Thanks for trying it this way! I like the overall simplification but\\n> > > this aspect is not great.\\n> > > Hmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\n> > > their own allocations and returning a pointer. Would it be less tricky\\n> > > if the structs were declared where we need them and passed to \\\"init\\\"\\n> > > functions?\\n> >\\n> > Seems worth trying. The current RT_CREATE() API is also convenient as\\n> > other data structure such as simplehash.h and dshash.c supports a\\n> > similar\\n>\\n> I don't happen to know if these paths had to solve similar trickiness\\n> with some values being local, and some shared.\\n>\\n> > > That may be a good idea for other reasons. It's awkward that the\\n> > > create function is declared like this:\\n> > >\\n> > > #ifdef RT_SHMEM\\n> > > RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes,\\n> > > dsa_area *dsa,\\n> > > int tranche_id);\\n> > > #else\\n> > > RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes);\\n> > > #endif\\n> > >\\n> > > An init function wouldn't need these parameters: it could look at the\\n> > > passed struct to know what to do.\\n> >\\n> > But the init function would initialize leaf_ctx etc,no? Initializing\\n> > leaf_ctx needs max_bytes that is not stored in RT_RADIX_TREE.\\n>\\n> I was more referring to the parameters that were different above\\n> depending on shared memory. My first thought was that the tricky part\\n> is because of the allocation in local memory, but it's certainly\\n> possible I've misunderstood the problem.\\n>\\n> > The same\\n> > is true for dsa. I imagined that an init function would allocate a DSA\\n> > memory for the control object.\\n>\\n> Yes:\\n>\\n> ...\\n> // embedded in VacDeadItems\\n> TidStore items;\\n> };\\n>\\n> // NULL DSA in local case, etc\\n> dead_items->items.area = dead_items_dsa;\\n> dead_items->items.tranche_id = FOO_ID;\\n>\\n> TidStoreInit(&dead_items->items, vac_work_mem);\\n>\\n> That's how I imagined it would work (leaving out some details). I\\n> haven't tried it, so not sure how much it helps. Maybe it has other\\n> problems, but I'm hoping it's just a matter of programming.\\n\\nIt seems we cannot make this work nicely. IIUC VacDeadItems is\\nallocated in DSM and TidStore is embedded there. However,\\ndead_items->items.area is a local pointer to dsa_area. So we cannot\\ninclude dsa_area in neither TidStore nor RT_RADIX_TREE. Instead we\\nwould need to pass dsa_area to each interface by callers.\\n\\n>\\n> If we can't make this work nicely, I'd be okay with keeping the tid\\n> store control object. My biggest concern is unnecessary\\n> double-locking.\\n\\nIf we don't do any locking stuff in radix tree APIs and it's the\\nuser's responsibility at all, probably we don't need a lock for\\ntidstore? That is, we expose lock functions as you mentioned and the\\nuser (like tidstore) acquires/releases the lock before/after accessing\\nthe radix tree and num_items. Currently (as of v52 patch) RT_FIND is\\ndoing so, but we would need to change RT_SET() and iteration functions\\nas well.\\n\\nDuring trying this idea, I realized that there is a visibility problem\\nin the radix tree template especially if we want to embed the radix\\ntree in a struct. Considering a use case where we want to use a radix\\ntree in an exposed struct, we would declare only interfaces in a .h\\nfile and define actual implementation in a .c file (FYI\\nTupleHashTableData does a similar thing with simplehash.h). The .c\\nfile and .h file would be like:\\n\\nin .h file:\\n#define RT_PREFIX local_rt\\n#define RT_SCOPE extern\\n#define RT_DECLARE\\n#define RT_VALUE_TYPE BlocktableEntry\\n#define RT_VARLEN_VALUE\\n#include \\\"lib/radixtree.h\\\"\\n\\ntypedef struct TidStore\\n{\\n:\\n local_rt_radix_tree tree; /* embedded */\\n:\\n} TidStore;\\n\\nin .c file:\\n\\n#define RT_PREFIX local_rt\\n#define RT_SCOPE extern\\n#define RT_DEFINE\\n#define RT_VALUE_TYPE BlocktableEntry\\n#define RT_VARLEN_VALUE\\n#include \\\"lib/radixtree.h\\\"\\n\\nBut it doesn't work as the compiler doesn't know the actual definition\\nof local_rt_radix_tree. If the 'tree' is *local_rt_radix_tree, it\\nworks. The reason is that with RT_DECLARE but without RT_DEFINE, the\\nradix tree template generates only forward declarations:\\n\\n#ifdef RT_DECLARE\\n\\ntypedef struct RT_RADIX_TREE RT_RADIX_TREE;\\ntypedef struct RT_ITER RT_ITER;\\n\\nIn order to make it work, we need to move the definitions required to\\nexpose RT_RADIX_TREE struct to RT_DECLARE part, which actually\\nrequires to move RT_NODE, RT_HANDLE, RT_NODE_PTR, RT_SIZE_CLASS_COUNT,\\nand RT_RADIX_TREE_CONTROL etc. However RT_SIZE_CLASS_COUNT, used in\\nRT_RADIX_TREE, could be bothersome. Since it refers to\\nRT_SIZE_CLASS_INFO that further refers to many #defines and structs,\\nwe might end up moving many structs such as RT_NODE_4 etc to\\nRT_DECLARE part as well. Or we can use a fixed number is stead of\\n\\\"lengthof(RT_SIZE_CLASS_INFO)\\\". Apart from that, macros requried by\\nboth RT_DECLARE and RT_DEFINE such as RT_PAN and RT_MAX_LEVEL also\\nneeds to be moved to a common place where they are defined in both\\ncases.\\n\\nGiven these facts, I think that the current abstraction works nicely\\nand it would make sense not to support embedding the radix tree.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 18 Jan 2024 10:30:54 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 18, 2024 at 8:31 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> It seems we cannot make this work nicely. IIUC VacDeadItems is\\n> allocated in DSM and TidStore is embedded there. However,\\n> dead_items->items.area is a local pointer to dsa_area. So we cannot\\n> include dsa_area in neither TidStore nor RT_RADIX_TREE. Instead we\\n> would need to pass dsa_area to each interface by callers.\\n\\nThanks again for exploring this line of thinking! Okay, it seems even\\nif there's a way to make this work, it would be too invasive to\\njustify when compared with the advantage I was hoping for.\\n\\n> > If we can't make this work nicely, I'd be okay with keeping the tid\\n> > store control object. My biggest concern is unnecessary\\n> > double-locking.\\n>\\n> If we don't do any locking stuff in radix tree APIs and it's the\\n> user's responsibility at all, probably we don't need a lock for\\n> tidstore? That is, we expose lock functions as you mentioned and the\\n> user (like tidstore) acquires/releases the lock before/after accessing\\n> the radix tree and num_items.\\n\\nI'm not quite sure what the point of \\\"num_items\\\" is anymore, because\\nit was really tied to the array in VacDeadItems. dead_items->num_items\\nis essential to reading/writing the array correctly. If this number is\\nwrong, the array is corrupt. There is no such requirement for the\\nradix tree. We don't need to know the number of tids to add to it or\\ndo a lookup, or anything.\\n\\nThere are a number of places where we assert \\\"the running count of the\\ndead items\\\" is the same as \\\"the length of the dead items array\\\", like\\nhere:\\n\\n@@ -2214,7 +2205,7 @@ lazy_vacuum(LVRelState *vacrel)\\n BlockNumber threshold;\\n\\n Assert(vacrel->num_index_scans == 0);\\n- Assert(vacrel->lpdead_items == vacrel->dead_items->num_items);\\n+ Assert(vacrel->lpdead_items == TidStoreNumTids(vacrel->dead_items));\\n\\nAs such, in HEAD I'm guessing it's arbitrary which one is used for\\ncontrol flow. Correct me if I'm mistaken. If I am wrong for some part\\nof the code, it'd be good to understand when that invariant can't be\\nmaintained.\\n\\n@@ -1258,7 +1265,7 @@ lazy_scan_heap(LVRelState *vacrel)\\n * Do index vacuuming (call each index's ambulkdelete routine), then do\\n * related heap vacuuming\\n */\\n- if (dead_items->num_items > 0)\\n+ if (TidStoreNumTids(dead_items) > 0)\\n lazy_vacuum(vacrel);\\n\\nLike here. In HEAD, could this have used vacrel->dead_items?\\n\\n@@ -2479,14 +2473,14 @@ lazy_vacuum_heap_rel(LVRelState *vacrel)\\n * We set all LP_DEAD items from the first heap pass to LP_UNUSED during\\n * the second heap pass. No more, no less.\\n */\\n- Assert(index > 0);\\n Assert(vacrel->num_index_scans > 1 ||\\n- (index == vacrel->lpdead_items &&\\n+ (TidStoreNumTids(vacrel->dead_items) == vacrel->lpdead_items &&\\n vacuumed_pages == vacrel->lpdead_item_pages));\\n\\n ereport(DEBUG2,\\n- (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed %lld dead item identifiers in %u pages\\\",\\n- vacrel->relname, (long long) index, vacuumed_pages)));\\n+ (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed \\\" INT64_FORMAT \\\"dead item identifiers\\nin %u pages\\\",\\n+ vacrel->relname, TidStoreNumTids(vacrel->dead_items),\\n+ vacuumed_pages)));\\n\\nWe assert that vacrel->lpdead_items has the expected value, and then\\nthe ereport repeats the function call (with a lock) to read the value\\nwe just consulted to pass the assert.\\n\\nIf we *really* want to compare counts, maybe we could invent a\\ndebugging-only function that iterates over the tree and popcounts the\\nbitmaps. That seems too expensive for regular assert builds, though.\\n\\nOn the subject of debugging builds, I think it no longer makes sense\\nto have the array for debug checking in tid store, even during\\ndevelopment. A few months ago, we had an encoding scheme that looked\\nsimple on paper, but its code was fiendishly difficult to follow (at\\nleast for me). That's gone. In addition to the debugging count above,\\nwe could also put a copy of the key in the BlockTableEntry's header,\\nin debug builds. We don't yet need to care about the key size, since\\nwe don't (yet) have runtime-embeddable values.\\n\\n> Currently (as of v52 patch) RT_FIND is\\n> doing so,\\n\\n[meaning, there is no internal \\\"automatic\\\" locking here since after we\\nswitched to variable-length types, an outstanding TODO]\\nMaybe it's okay to expose global locking for v17. I have one possible\\nalternative:\\n\\nThis week I tried an idea to use a callback there so that after\\ninternal unlocking, the caller received the value (or whatever else\\nneeds to happen, such as lookup an offset in the tid bitmap). I've\\nattached a draft for that that passes radix tree tests. It's a bit\\nawkward, but I'm guessing this would more closely match future\\ninternal atomic locking. Let me know what you think of the concept,\\nand then do whichever way you think is best. (using v53 as the basis)\\n\\nI believe this is the only open question remaining. The rest is just\\npolish and testing.\\n\\n> During trying this idea, I realized that there is a visibility problem\\n> in the radix tree template\\n\\nIf it's broken even without the embedding I'll look into this (I don't\\nknow if this configuration has ever been tested). I think a good test\\nis putting the shared tid tree in it's own translation unit, to see if\\nanything needs to be fixed. I'll go try that.\",\n \"msg_date\": \"Thu, 18 Jan 2024 11:30:01 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Jan 18, 2024 at 1:30 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Jan 18, 2024 at 8:31 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > It seems we cannot make this work nicely. IIUC VacDeadItems is\\n> > allocated in DSM and TidStore is embedded there. However,\\n> > dead_items->items.area is a local pointer to dsa_area. So we cannot\\n> > include dsa_area in neither TidStore nor RT_RADIX_TREE. Instead we\\n> > would need to pass dsa_area to each interface by callers.\\n>\\n> Thanks again for exploring this line of thinking! Okay, it seems even\\n> if there's a way to make this work, it would be too invasive to\\n> justify when compared with the advantage I was hoping for.\\n>\\n> > > If we can't make this work nicely, I'd be okay with keeping the tid\\n> > > store control object. My biggest concern is unnecessary\\n> > > double-locking.\\n> >\\n> > If we don't do any locking stuff in radix tree APIs and it's the\\n> > user's responsibility at all, probably we don't need a lock for\\n> > tidstore? That is, we expose lock functions as you mentioned and the\\n> > user (like tidstore) acquires/releases the lock before/after accessing\\n> > the radix tree and num_items.\\n>\\n> I'm not quite sure what the point of \\\"num_items\\\" is anymore, because\\n> it was really tied to the array in VacDeadItems. dead_items->num_items\\n> is essential to reading/writing the array correctly. If this number is\\n> wrong, the array is corrupt. There is no such requirement for the\\n> radix tree. We don't need to know the number of tids to add to it or\\n> do a lookup, or anything.\\n\\nTrue. Sorry I wanted to say \\\"num_tids\\\" of TidStore. I'm still thinking\\nwe need to have the number of TIDs in a tidstore, especially in the\\ntidstore's control object.\\n\\n>\\n> There are a number of places where we assert \\\"the running count of the\\n> dead items\\\" is the same as \\\"the length of the dead items array\\\", like\\n> here:\\n>\\n> @@ -2214,7 +2205,7 @@ lazy_vacuum(LVRelState *vacrel)\\n> BlockNumber threshold;\\n>\\n> Assert(vacrel->num_index_scans == 0);\\n> - Assert(vacrel->lpdead_items == vacrel->dead_items->num_items);\\n> + Assert(vacrel->lpdead_items == TidStoreNumTids(vacrel->dead_items));\\n>\\n> As such, in HEAD I'm guessing it's arbitrary which one is used for\\n> control flow. Correct me if I'm mistaken. If I am wrong for some part\\n> of the code, it'd be good to understand when that invariant can't be\\n> maintained.\\n>\\n> @@ -1258,7 +1265,7 @@ lazy_scan_heap(LVRelState *vacrel)\\n> * Do index vacuuming (call each index's ambulkdelete routine), then do\\n> * related heap vacuuming\\n> */\\n> - if (dead_items->num_items > 0)\\n> + if (TidStoreNumTids(dead_items) > 0)\\n> lazy_vacuum(vacrel);\\n>\\n> Like here. In HEAD, could this have used vacrel->dead_items?\\n>\\n> @@ -2479,14 +2473,14 @@ lazy_vacuum_heap_rel(LVRelState *vacrel)\\n> * We set all LP_DEAD items from the first heap pass to LP_UNUSED during\\n> * the second heap pass. No more, no less.\\n> */\\n> - Assert(index > 0);\\n> Assert(vacrel->num_index_scans > 1 ||\\n> - (index == vacrel->lpdead_items &&\\n> + (TidStoreNumTids(vacrel->dead_items) == vacrel->lpdead_items &&\\n> vacuumed_pages == vacrel->lpdead_item_pages));\\n>\\n> ereport(DEBUG2,\\n> - (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed %lld dead item identifiers in %u pages\\\",\\n> - vacrel->relname, (long long) index, vacuumed_pages)));\\n> + (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed \\\" INT64_FORMAT \\\"dead item identifiers\\n> in %u pages\\\",\\n> + vacrel->relname, TidStoreNumTids(vacrel->dead_items),\\n> + vacuumed_pages)));\\n>\\n> We assert that vacrel->lpdead_items has the expected value, and then\\n> the ereport repeats the function call (with a lock) to read the value\\n> we just consulted to pass the assert.\\n>\\n> If we *really* want to compare counts, maybe we could invent a\\n> debugging-only function that iterates over the tree and popcounts the\\n> bitmaps. That seems too expensive for regular assert builds, though.\\n\\nIIUC lpdead_items is the total number of LP_DEAD items vacuumed during\\nthe whole lazy vacuum operation whereas num_items is the number of\\nLP_DEAD items vacuumed within one index vacuum and heap vacuum cycle.\\nThat is, after heap vacuum, the latter counter is reset while the\\nformer counter is not.\\n\\nThe latter counter is used in lazyvacuum.c as well as the ereport in\\nvac_bulkdel_one_index().\\n\\n>\\n> On the subject of debugging builds, I think it no longer makes sense\\n> to have the array for debug checking in tid store, even during\\n> development. A few months ago, we had an encoding scheme that looked\\n> simple on paper, but its code was fiendishly difficult to follow (at\\n> least for me). That's gone. In addition to the debugging count above,\\n> we could also put a copy of the key in the BlockTableEntry's header,\\n> in debug builds. We don't yet need to care about the key size, since\\n> we don't (yet) have runtime-embeddable values.\\n\\nPutting a copy of the key in BlocktableEntry's header is an\\ninteresting idea. But the current debug code in the tidstore also\\nmakes sure that the tidstore returns TIDs in the correct order during\\nan iterate operation. I think it still has a value and you can disable\\nit by removing the \\\"#define TIDSTORE_DEBUG\\\" line.\\n\\n>\\n> > Currently (as of v52 patch) RT_FIND is\\n> > doing so,\\n>\\n> [meaning, there is no internal \\\"automatic\\\" locking here since after we\\n> switched to variable-length types, an outstanding TODO]\\n> Maybe it's okay to expose global locking for v17. I have one possible\\n> alternative:\\n>\\n> This week I tried an idea to use a callback there so that after\\n> internal unlocking, the caller received the value (or whatever else\\n> needs to happen, such as lookup an offset in the tid bitmap). I've\\n> attached a draft for that that passes radix tree tests. It's a bit\\n> awkward, but I'm guessing this would more closely match future\\n> internal atomic locking. Let me know what you think of the concept,\\n> and then do whichever way you think is best. (using v53 as the basis)\\n\\nThank you for verifying this idea! Interesting. While it's promising\\nin terms of future atomic locking, I'm concerned it might not be easy\\nto use if radix tree APIs supports only such callback style. I believe\\nthe caller would like to pass one more data along with val_data. For\\nexample, considering tidstore that has num_tids internally, it wants\\nto pass both a pointer to BlocktableEntry and a pointer to TidStore\\nitself so that it increments the counter while holding a lock.\\n\\nAnother API idea for future atomic locking is to separate\\nRT_SET()/RT_FIND() into begin and end. In RT_SET_BEGIN() API, we find\\nthe key, extend nodes if necessary, set the value, and return the\\nresult while holding the lock. For example, if the radix tree supports\\nlock coupling, the leaf node and its parent remain locked. Then the\\ncaller does its job and calls RT_SET_END() that does cleanup stuff\\nsuch as releasing locks.\\n\\nI've not fully considered this approach but even this idea seems\\ncomplex and easy to use. I prefer the current simple approach as we\\nsupport the simple locking mechanism for now.\\n\\n>\\n> I believe this is the only open question remaining. The rest is just\\n> polish and testing.\\n\\nRight.\\n\\n>\\n> > During trying this idea, I realized that there is a visibility problem\\n> > in the radix tree template\\n>\\n> If it's broken even without the embedding I'll look into this (I don't\\n> know if this configuration has ever been tested). I think a good test\\n> is putting the shared tid tree in it's own translation unit, to see if\\n> anything needs to be fixed. I'll go try that.\\n\\nThanks.\\n\\nBTW in radixtree.h pg_attribute_unused() is used for some functions,\\nbut is it for debugging purposes? I don't see why it's used only for\\nsome functions.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Jan 2024 16:26:17 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 19, 2024 at 2:26 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Jan 18, 2024 at 1:30 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > I'm not quite sure what the point of \\\"num_items\\\" is anymore, because\\n> > it was really tied to the array in VacDeadItems. dead_items->num_items\\n> > is essential to reading/writing the array correctly. If this number is\\n> > wrong, the array is corrupt. There is no such requirement for the\\n> > radix tree. We don't need to know the number of tids to add to it or\\n> > do a lookup, or anything.\\n>\\n> True. Sorry I wanted to say \\\"num_tids\\\" of TidStore. I'm still thinking\\n> we need to have the number of TIDs in a tidstore, especially in the\\n> tidstore's control object.\\n\\nHmm, it would be kind of sad to require explicit locking in tidstore.c\\nis only for maintaining that one number at all times. Aside from the\\ntwo ereports after an index scan / second heap pass, the only\\nnon-assert place where it's used is\\n\\n@@ -1258,7 +1265,7 @@ lazy_scan_heap(LVRelState *vacrel)\\n * Do index vacuuming (call each index's ambulkdelete routine), then do\\n * related heap vacuuming\\n */\\n- if (dead_items->num_items > 0)\\n+ if (TidStoreNumTids(dead_items) > 0)\\n lazy_vacuum(vacrel);\\n\\n...and that condition can be checked by doing a single step of\\niteration to see if it shows anything. But for the ereport, my idea\\nfor iteration + popcount is probably quite slow.\\n\\n> IIUC lpdead_items is the total number of LP_DEAD items vacuumed during\\n> the whole lazy vacuum operation whereas num_items is the number of\\n> LP_DEAD items vacuumed within one index vacuum and heap vacuum cycle.\\n> That is, after heap vacuum, the latter counter is reset while the\\n> former counter is not.\\n>\\n> The latter counter is used in lazyvacuum.c as well as the ereport in\\n> vac_bulkdel_one_index().\\n\\nAh, of course.\\n\\n> Putting a copy of the key in BlocktableEntry's header is an\\n> interesting idea. But the current debug code in the tidstore also\\n> makes sure that the tidstore returns TIDs in the correct order during\\n> an iterate operation. I think it still has a value and you can disable\\n> it by removing the \\\"#define TIDSTORE_DEBUG\\\" line.\\n\\nFair enough. I just thought it'd be less work to leave this out in\\ncase we change how locking is called.\\n\\n> > This week I tried an idea to use a callback there so that after\\n> > internal unlocking, the caller received the value (or whatever else\\n> > needs to happen, such as lookup an offset in the tid bitmap). I've\\n> > attached a draft for that that passes radix tree tests. It's a bit\\n> > awkward, but I'm guessing this would more closely match future\\n> > internal atomic locking. Let me know what you think of the concept,\\n> > and then do whichever way you think is best. (using v53 as the basis)\\n>\\n> Thank you for verifying this idea! Interesting. While it's promising\\n> in terms of future atomic locking, I'm concerned it might not be easy\\n> to use if radix tree APIs supports only such callback style.\\n\\nYeah, it's quite awkward. It could be helped by only exposing it for\\nvarlen types. For simply returning \\\"present or not\\\" (used a lot in the\\nregression tests), we could skip the callback if the data is null.\\nThat is all also extra stuff.\\n\\n> I believe\\n> the caller would like to pass one more data along with val_data. For\\n\\nThat's trivial, however, if I understand you correctly. With \\\"void *\\\",\\na callback can receive anything, including a struct containing\\nadditional pointers to elsewhere.\\n\\n> example, considering tidstore that has num_tids internally, it wants\\n> to pass both a pointer to BlocktableEntry and a pointer to TidStore\\n> itself so that it increments the counter while holding a lock.\\n\\nHmm, so a callback to RT_SET also. That's interesting!\\n\\nAnyway, I agree it needs to be simple, since the first use doesn't\\neven have multiple writers.\\n\\n> BTW in radixtree.h pg_attribute_unused() is used for some functions,\\n> but is it for debugging purposes? I don't see why it's used only for\\n> some functions.\\n\\nIt was there to silence warnings about unused functions. I only see\\none remaining, and it's already behind a debug symbol, so we might not\\nneed this attribute anymore.\\n\\n\\n\",\n \"msg_date\": \"Fri, 19 Jan 2024 16:48:23 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n\\n> On Thu, Jan 18, 2024 at 8:31 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > During trying this idea, I realized that there is a visibility problem\\n> > in the radix tree template\\n>\\n> If it's broken even without the embedding I'll look into this (I don't\\n> know if this configuration has ever been tested). I think a good test\\n> is putting the shared tid tree in it's own translation unit, to see if\\n> anything needs to be fixed. I'll go try that.\\n\\nHere's a quick test that this works. The only thing that really needed\\nfixing in the template was failure to un-define one symbol. The rest\\nwas just moving some things around.\",\n \"msg_date\": \"Fri, 19 Jan 2024 18:27:09 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 19, 2024 at 6:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Jan 19, 2024 at 2:26 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Jan 18, 2024 at 1:30 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > I'm not quite sure what the point of \\\"num_items\\\" is anymore, because\\n> > > it was really tied to the array in VacDeadItems. dead_items->num_items\\n> > > is essential to reading/writing the array correctly. If this number is\\n> > > wrong, the array is corrupt. There is no such requirement for the\\n> > > radix tree. We don't need to know the number of tids to add to it or\\n> > > do a lookup, or anything.\\n> >\\n> > True. Sorry I wanted to say \\\"num_tids\\\" of TidStore. I'm still thinking\\n> > we need to have the number of TIDs in a tidstore, especially in the\\n> > tidstore's control object.\\n>\\n> Hmm, it would be kind of sad to require explicit locking in tidstore.c\\n> is only for maintaining that one number at all times. Aside from the\\n> two ereports after an index scan / second heap pass, the only\\n> non-assert place where it's used is\\n>\\n> @@ -1258,7 +1265,7 @@ lazy_scan_heap(LVRelState *vacrel)\\n> * Do index vacuuming (call each index's ambulkdelete routine), then do\\n> * related heap vacuuming\\n> */\\n> - if (dead_items->num_items > 0)\\n> + if (TidStoreNumTids(dead_items) > 0)\\n> lazy_vacuum(vacrel);\\n>\\n> ...and that condition can be checked by doing a single step of\\n> iteration to see if it shows anything. But for the ereport, my idea\\n> for iteration + popcount is probably quite slow.\\n\\nRight.\\n\\nOn further thought, as you pointed out before, \\\"num_tids\\\" should not\\nbe in tidstore in terms of integration with tidbitmap.c, because\\ntidbitmap.c has \\\"lossy pages\\\". With lossy pages, \\\"num_tids\\\" is no\\nlonger accurate and useful. Similarly, looking at tidbitmap.c, it has\\nnpages and nchunks but they will not be necessary in lazy vacuum use\\ncase. Also, assuming that we support parallel heap pruning, probably\\nwe need to somehow lock the tidstore while adding tids to the tidstore\\nconcurrently by parallel vacuum worker. But in tidbitmap use case, we\\ndon't need to lock the tidstore since it doesn't have multiple\\nwriters. Given these facts, different statistics and different lock\\nstrategies are required by different use case. So I think there are 3\\noptions:\\n\\n1. expose lock functions for tidstore and the caller manages the\\nstatistics in the outside of tidstore. For example, in lazyvacuum.c we\\nwould have a TidStore for tid storage as well as VacDeadItemsInfo that\\nhas num_tids and max_bytes. Both are in LVRelState. For parallel\\nvacuum, we pass both to the workers via DSM and pass both to function\\nwhere the statistics are required. As for the exposed lock functions,\\nwhen adding tids to the tidstore, the caller would need to call\\nsomething like TidStoreLockExclusive(ts) that further calls\\nLWLockAcquire(ts->tree.shared->ctl.lock, LW_EXCLUSIVE) internally.\\n\\n2. add callback functions to tidstore so that the caller can do its\\nwork while holding a lock on the tidstore. This is like the idea we\\njust discussed for radix tree. The caller passes a callback function\\nand user data to TidStoreSetBlockOffsets(), and the callback is called\\nafter setting tids. Similar to option 1, the statistics need to be\\nstored in a different area.\\n\\n3. keep tidstore.c and tidbitmap.c separate implementations but use\\nradix tree in tidbitmap.c. tidstore.c would have \\\"num_tids\\\" in its\\ncontrol object and doesn't have any lossy page support. On the other\\nhand, in tidbitmap.c we replace simplehash with radix tree. This makes\\ntidstore.c simple but we would end up having different data structures\\nfor similar usage.\\n\\nI think it's worth trying option 1. What do you think, John?\\n\\n>\\n> > IIUC lpdead_items is the total number of LP_DEAD items vacuumed during\\n> > the whole lazy vacuum operation whereas num_items is the number of\\n> > LP_DEAD items vacuumed within one index vacuum and heap vacuum cycle.\\n> > That is, after heap vacuum, the latter counter is reset while the\\n> > former counter is not.\\n> >\\n> > The latter counter is used in lazyvacuum.c as well as the ereport in\\n> > vac_bulkdel_one_index().\\n>\\n> Ah, of course.\\n>\\n> > Putting a copy of the key in BlocktableEntry's header is an\\n> > interesting idea. But the current debug code in the tidstore also\\n> > makes sure that the tidstore returns TIDs in the correct order during\\n> > an iterate operation. I think it still has a value and you can disable\\n> > it by removing the \\\"#define TIDSTORE_DEBUG\\\" line.\\n>\\n> Fair enough. I just thought it'd be less work to leave this out in\\n> case we change how locking is called.\\n>\\n> > > This week I tried an idea to use a callback there so that after\\n> > > internal unlocking, the caller received the value (or whatever else\\n> > > needs to happen, such as lookup an offset in the tid bitmap). I've\\n> > > attached a draft for that that passes radix tree tests. It's a bit\\n> > > awkward, but I'm guessing this would more closely match future\\n> > > internal atomic locking. Let me know what you think of the concept,\\n> > > and then do whichever way you think is best. (using v53 as the basis)\\n> >\\n> > Thank you for verifying this idea! Interesting. While it's promising\\n> > in terms of future atomic locking, I'm concerned it might not be easy\\n> > to use if radix tree APIs supports only such callback style.\\n>\\n> Yeah, it's quite awkward. It could be helped by only exposing it for\\n> varlen types. For simply returning \\\"present or not\\\" (used a lot in the\\n> regression tests), we could skip the callback if the data is null.\\n> That is all also extra stuff.\\n>\\n> > I believe\\n> > the caller would like to pass one more data along with val_data. For\\n>\\n> That's trivial, however, if I understand you correctly. With \\\"void *\\\",\\n> a callback can receive anything, including a struct containing\\n> additional pointers to elsewhere.\\n>\\n> > example, considering tidstore that has num_tids internally, it wants\\n> > to pass both a pointer to BlocktableEntry and a pointer to TidStore\\n> > itself so that it increments the counter while holding a lock.\\n>\\n> Hmm, so a callback to RT_SET also. That's interesting!\\n>\\n> Anyway, I agree it needs to be simple, since the first use doesn't\\n> even have multiple writers.\\n\\nRight.\\n\\n>\\n> > BTW in radixtree.h pg_attribute_unused() is used for some functions,\\n> > but is it for debugging purposes? I don't see why it's used only for\\n> > some functions.\\n>\\n> It was there to silence warnings about unused functions. I only see\\n> one remaining, and it's already behind a debug symbol, so we might not\\n> need this attribute anymore.\\n\\nOkay.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Jan 2024 12:27:36 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 22, 2024 at 10:28 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On further thought, as you pointed out before, \\\"num_tids\\\" should not\\n> be in tidstore in terms of integration with tidbitmap.c, because\\n> tidbitmap.c has \\\"lossy pages\\\". With lossy pages, \\\"num_tids\\\" is no\\n> longer accurate and useful. Similarly, looking at tidbitmap.c, it has\\n> npages and nchunks but they will not be necessary in lazy vacuum use\\n> case. Also, assuming that we support parallel heap pruning, probably\\n> we need to somehow lock the tidstore while adding tids to the tidstore\\n> concurrently by parallel vacuum worker. But in tidbitmap use case, we\\n> don't need to lock the tidstore since it doesn't have multiple\\n> writers.\\n\\nNot currently, and it does seem bad to require locking where it's not required.\\n\\n(That would be a prerequisite for parallel index scan. It's been tried\\nbefore with the hash table, but concurrency didn't scale well with the\\nhash table. I have no reason to think that the radix tree would scale\\nsignificantly better with the same global LW lock, but as you know\\nthere are other locking schemes possible.)\\n\\n> Given these facts, different statistics and different lock\\n> strategies are required by different use case. So I think there are 3\\n> options:\\n>\\n> 1. expose lock functions for tidstore and the caller manages the\\n> statistics in the outside of tidstore. For example, in lazyvacuum.c we\\n> would have a TidStore for tid storage as well as VacDeadItemsInfo that\\n> has num_tids and max_bytes. Both are in LVRelState. For parallel\\n> vacuum, we pass both to the workers via DSM and pass both to function\\n> where the statistics are required. As for the exposed lock functions,\\n> when adding tids to the tidstore, the caller would need to call\\n> something like TidStoreLockExclusive(ts) that further calls\\n> LWLockAcquire(ts->tree.shared->ctl.lock, LW_EXCLUSIVE) internally.\\n\\nThe advantage here is that vacuum can avoid locking entirely while\\nusing shared memory, just like it does now, and has the option to add\\nit later.\\nIIUC, the radix tree struct would have a lock member, but wouldn't\\ntake any locks internally? Maybe we still need one for\\nRT_MEMORY_USAGE? For that, I see dsa_get_total_size() takes its own\\nDSA_AREA_LOCK -- maybe that's enough?\\n\\nThat seems simplest, and is not very far from what we do now. If we do\\nthis, then the lock functions should be where we branch for is_shared.\\n\\n> 2. add callback functions to tidstore so that the caller can do its\\n> work while holding a lock on the tidstore. This is like the idea we\\n> just discussed for radix tree. The caller passes a callback function\\n> and user data to TidStoreSetBlockOffsets(), and the callback is called\\n> after setting tids. Similar to option 1, the statistics need to be\\n> stored in a different area.\\n\\nI think we'll have to move to something like this eventually, but it\\nseems like overkill right now.\\n\\n> 3. keep tidstore.c and tidbitmap.c separate implementations but use\\n> radix tree in tidbitmap.c. tidstore.c would have \\\"num_tids\\\" in its\\n> control object and doesn't have any lossy page support. On the other\\n> hand, in tidbitmap.c we replace simplehash with radix tree. This makes\\n> tidstore.c simple but we would end up having different data structures\\n> for similar usage.\\n\\nThey have so much in common that it's worth it to use the same\\ninterface and (eventually) value type. They just need separate paths\\nfor adding tids, as we've discussed.\\n\\n> I think it's worth trying option 1. What do you think, John?\\n\\n+1\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Jan 2024 12:35:49 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 17, 2024 at 12:32 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I wrote:\\n>\\n> > > Hmm, I wonder if that's a side-effect of the \\\"create\\\" functions doing\\n> > > their own allocations and returning a pointer. Would it be less tricky\\n> > > if the structs were declared where we need them and passed to \\\"init\\\"\\n> > > functions?\\n>\\n> If this is a possibility, I thought I'd first send the last (I hope)\\n> large-ish set of radix tree cleanups to avoid rebasing issues. I'm not\\n> including tidstore/vacuum here, because recent discussion has some\\n> up-in-the-air work.\\n\\nThank you for updating the patches! These updates look good to me.\\n\\n>\\n> Should be self-explanatory, but some thing are worth calling out:\\n> 0012 and 0013: Some time ago I started passing insertpos as a\\n> parameter, but now see that is not ideal -- when growing from node16\\n> to node48 we don't need it at all, so it's a wasted calculation. While\\n> reverting that, I found that this also allows passing constants in\\n> some cases.\\n> 0014 makes a cleaner separation between adding a child and growing a\\n> node, resulting in more compact-looking functions.\\n> 0019 is a bit unpolished, but I realized that it's pointless to assign\\n> a zero child when further up the call stack we overwrite it anyway\\n> with the actual value. With this, that assignment is skipped. This\\n> makes some comments and names strange, so needs a bit of polish, but\\n> wanted to get it out there anyway.\\n\\nCool.\\n\\nI'll merge these patches in the next version v54 patch set.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Jan 2024 16:00:08 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 22, 2024 at 2:36 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Jan 22, 2024 at 10:28 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On further thought, as you pointed out before, \\\"num_tids\\\" should not\\n> > be in tidstore in terms of integration with tidbitmap.c, because\\n> > tidbitmap.c has \\\"lossy pages\\\". With lossy pages, \\\"num_tids\\\" is no\\n> > longer accurate and useful. Similarly, looking at tidbitmap.c, it has\\n> > npages and nchunks but they will not be necessary in lazy vacuum use\\n> > case. Also, assuming that we support parallel heap pruning, probably\\n> > we need to somehow lock the tidstore while adding tids to the tidstore\\n> > concurrently by parallel vacuum worker. But in tidbitmap use case, we\\n> > don't need to lock the tidstore since it doesn't have multiple\\n> > writers.\\n>\\n> Not currently, and it does seem bad to require locking where it's not required.\\n>\\n> (That would be a prerequisite for parallel index scan. It's been tried\\n> before with the hash table, but concurrency didn't scale well with the\\n> hash table. I have no reason to think that the radix tree would scale\\n> significantly better with the same global LW lock, but as you know\\n> there are other locking schemes possible.)\\n>\\n> > Given these facts, different statistics and different lock\\n> > strategies are required by different use case. So I think there are 3\\n> > options:\\n> >\\n> > 1. expose lock functions for tidstore and the caller manages the\\n> > statistics in the outside of tidstore. For example, in lazyvacuum.c we\\n> > would have a TidStore for tid storage as well as VacDeadItemsInfo that\\n> > has num_tids and max_bytes. Both are in LVRelState. For parallel\\n> > vacuum, we pass both to the workers via DSM and pass both to function\\n> > where the statistics are required. As for the exposed lock functions,\\n> > when adding tids to the tidstore, the caller would need to call\\n> > something like TidStoreLockExclusive(ts) that further calls\\n> > LWLockAcquire(ts->tree.shared->ctl.lock, LW_EXCLUSIVE) internally.\\n>\\n> The advantage here is that vacuum can avoid locking entirely while\\n> using shared memory, just like it does now, and has the option to add\\n> it later.\\n\\nTrue.\\n\\n> IIUC, the radix tree struct would have a lock member, but wouldn't\\n> take any locks internally? Maybe we still need one for\\n> RT_MEMORY_USAGE? For that, I see dsa_get_total_size() takes its own\\n> DSA_AREA_LOCK -- maybe that's enough?\\n\\nI think that's a good point. So there will be no place where the radix\\ntree takes any locks internally.\\n\\n>\\n> That seems simplest, and is not very far from what we do now. If we do\\n> this, then the lock functions should be where we branch for is_shared.\\n\\nAgreed.\\n\\n>\\n> > 2. add callback functions to tidstore so that the caller can do its\\n> > work while holding a lock on the tidstore. This is like the idea we\\n> > just discussed for radix tree. The caller passes a callback function\\n> > and user data to TidStoreSetBlockOffsets(), and the callback is called\\n> > after setting tids. Similar to option 1, the statistics need to be\\n> > stored in a different area.\\n>\\n> I think we'll have to move to something like this eventually, but it\\n> seems like overkill right now.\\n\\nRight.\\n\\n>\\n> > 3. keep tidstore.c and tidbitmap.c separate implementations but use\\n> > radix tree in tidbitmap.c. tidstore.c would have \\\"num_tids\\\" in its\\n> > control object and doesn't have any lossy page support. On the other\\n> > hand, in tidbitmap.c we replace simplehash with radix tree. This makes\\n> > tidstore.c simple but we would end up having different data structures\\n> > for similar usage.\\n>\\n> They have so much in common that it's worth it to use the same\\n> interface and (eventually) value type. They just need separate paths\\n> for adding tids, as we've discussed.\\n\\nAgreed.\\n\\n>\\n> > I think it's worth trying option 1. What do you think, John?\\n>\\n> +1\\n\\nThanks!\\n\\nBefore working on this idea, since the latest patches conflict with\\nthe current HEAD, I share the latest patch set (v54). Here is the\\nsummary:\\n\\n- As for radix tree part, it's based on v53 patch. I've squashed most\\nof cleanups and changes in v53 except for \\\"DRAFT: Stop using invalid\\npointers as placeholders.\\\" as I thought you might want to still work\\non it. BTW it includes \\\"#undef RT_SHMEM\\\".\\n- As for tidstore, it's based on v51. That is, it still has the\\ncontrol object and num_tids there.\\n- As for vacuum integration, it's also based on v51. But we no longer\\nneed to change has_lpdead_items and LVPagePruneState thanks to the\\nrecent commit c120550edb8 and e313a61137.\\n\\nFor the next version patch, I'll work on this idea and try to clean up\\nlocking stuff both in tidstore and radix tree. Or if you're already\\nworking on some of them, please let me know. I'll review it.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 22 Jan 2024 16:23:43 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 22, 2024 at 2:24 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> For the next version patch, I'll work on this idea and try to clean up\\n> locking stuff both in tidstore and radix tree. Or if you're already\\n> working on some of them, please let me know. I'll review it.\\n\\nOkay go ahead, sounds good. I plan to look at the tests since they\\nhaven't been looked at in a while.\\n\\n\\n\",\n \"msg_date\": \"Mon, 22 Jan 2024 15:18:03 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 22, 2024 at 5:18 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Jan 22, 2024 at 2:24 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > For the next version patch, I'll work on this idea and try to clean up\\n> > locking stuff both in tidstore and radix tree. Or if you're already\\n> > working on some of them, please let me know. I'll review it.\\n>\\n> Okay go ahead, sounds good. I plan to look at the tests since they\\n> haven't been looked at in a while.\\n\\nI've attached the latest patch set. Here are updates from v54 patch:\\n\\n0005 - Expose radix tree lock functions and remove all locks taken\\ninternally in radixtree.h.\\n0008 - Remove tidstore's control object.\\n0009 - Add tidstore lock functions.\\n0011 - Add VacDeadItemsInfo to store \\\"max_bytes\\\" and \\\"num_items\\\"\\nseparate from TidStore. Also make lazy vacuum and parallel vacuum use\\nit.\\n\\nThe new patches probably need to be polished but the VacDeadItemInfo\\nidea looks good to me.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 23 Jan 2024 12:58:00 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 23, 2024 at 12:58 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Jan 22, 2024 at 5:18 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Mon, Jan 22, 2024 at 2:24 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > For the next version patch, I'll work on this idea and try to clean up\\n> > > locking stuff both in tidstore and radix tree. Or if you're already\\n> > > working on some of them, please let me know. I'll review it.\\n> >\\n> > Okay go ahead, sounds good. I plan to look at the tests since they\\n> > haven't been looked at in a while.\\n>\\n> I've attached the latest patch set. Here are updates from v54 patch:\\n>\\n> 0005 - Expose radix tree lock functions and remove all locks taken\\n> internally in radixtree.h.\\n> 0008 - Remove tidstore's control object.\\n> 0009 - Add tidstore lock functions.\\n> 0011 - Add VacDeadItemsInfo to store \\\"max_bytes\\\" and \\\"num_items\\\"\\n> separate from TidStore. Also make lazy vacuum and parallel vacuum use\\n> it.\\n\\nJohn pointed out offlist the tarball includes only the patches up to\\n0009. I've attached the correct one.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 23 Jan 2024 16:48:25 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 23, 2024 at 10:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> The new patches probably need to be polished but the VacDeadItemInfo\\n> idea looks good to me.\\n\\nThat idea looks good to me, too. Since you already likely know what\\nyou'd like to polish, I don't have much to say except for a few\\nquestions below. I also did a quick sweep through every patch, so some\\nof these comments are unrelated to recent changes:\\n\\nv55-0003:\\n\\n+size_t\\n+dsa_get_total_size(dsa_area *area)\\n+{\\n+ size_t size;\\n+\\n+ LWLockAcquire(DSA_AREA_LOCK(area), LW_SHARED);\\n+ size = area->control->total_segment_size;\\n+ LWLockRelease(DSA_AREA_LOCK(area));\\n\\nI looked and found dsa.c doesn't already use shared locks in HEAD,\\neven dsa_dump. Not sure why that is...\\n\\n+/*\\n+ * Calculate the slab blocksize so that we can allocate at least 32 chunks\\n+ * from the block.\\n+ */\\n+#define RT_SLAB_BLOCK_SIZE(size) \\\\\\n+ Max((SLAB_DEFAULT_BLOCK_SIZE / (size)) * (size), (size) * 32)\\n\\nThe first parameter seems to be trying to make the block size exact,\\nbut that's not right, because of the chunk header, and maybe\\nalignment. If the default block size is big enough to waste only a\\ntiny amount of space, let's just use that as-is. Also, I think all\\nblock sizes in the code base have been a power of two, but I'm not\\nsure how much that matters.\\n\\n+#ifdef RT_SHMEM\\n+ fprintf(stderr, \\\" [%d] chunk %x slot \\\" DSA_POINTER_FORMAT \\\"\\\\n\\\",\\n+ i, n4->chunks[i], n4->children[i]);\\n+#else\\n+ fprintf(stderr, \\\" [%d] chunk %x slot %p\\\\n\\\",\\n+ i, n4->chunks[i], n4->children[i]);\\n+#endif\\n\\nMaybe we could invent a child pointer format, so we only #ifdef in one place.\\n\\n--- /dev/null\\n+++ b/src/test/modules/test_radixtree/meson.build\\n@@ -0,0 +1,35 @@\\n+# FIXME: prevent install during main install, but not during test :/\\n\\nCan you look into this?\\n\\ntest_radixtree.c:\\n\\n+/*\\n+ * XXX: should we expose and use RT_SIZE_CLASS and RT_SIZE_CLASS_INFO?\\n+ */\\n+static int rt_node_class_fanouts[] = {\\n+ 4, /* RT_CLASS_3 */\\n+ 15, /* RT_CLASS_32_MIN */\\n+ 32, /* RT_CLASS_32_MAX */\\n+ 125, /* RT_CLASS_125 */\\n+ 256 /* RT_CLASS_256 */\\n+};\\n\\nThese numbers have been wrong a long time, too, but only matters for\\nfiguring out where it went wrong when something is broken. And for the\\nXXX, instead of trying to use the largest number that should fit (it's\\nobviously not testing that the expected node can actually hold that\\nnumber anyway), it seems we can just use a \\\"big enough\\\" number to\\ncause growing into the desired size class.\\n\\nAs far as cleaning up the tests, I always wondered why these didn't\\nuse EXPECT_TRUE, EXPECT_FALSE, etc. as in Andres's prototype where\\nwhere convenient, and leave comments above the tests. That seemed like\\na good idea to me -- was there a reason to have hand-written branches\\nand elog messages everywhere?\\n\\n--- a/src/tools/pginclude/cpluspluscheck\\n+++ b/src/tools/pginclude/cpluspluscheck\\n@@ -101,6 +101,12 @@ do\\n test \\\"$f\\\" = src/include/nodes/nodetags.h && continue\\n test \\\"$f\\\" = src/backend/nodes/nodetags.h && continue\\n\\n+ # radixtree_*_impl.h cannot be included standalone: they are just\\ncode fragments.\\n+ test \\\"$f\\\" = src/include/lib/radixtree_delete_impl.h && continue\\n+ test \\\"$f\\\" = src/include/lib/radixtree_insert_impl.h && continue\\n+ test \\\"$f\\\" = src/include/lib/radixtree_iter_impl.h && continue\\n+ test \\\"$f\\\" = src/include/lib/radixtree_search_impl.h && continue\\n\\nHa! I'd forgotten about these -- they're long outdated.\\n\\nv55-0005:\\n\\n- * The radix tree is locked in shared mode during the iteration, so\\n- * RT_END_ITERATE needs to be called when finished to release the lock.\\n+ * The caller needs to acquire a lock in shared mode during the iteration\\n+ * if necessary.\\n\\n\\\"need if necessary\\\" is maybe better phrased as \\\"is the caller's responsibility\\\"\\n\\n+ /*\\n+ * We can rely on DSA_AREA_LOCK to get the total amount of DSA memory.\\n+ */\\n total = dsa_get_total_size(tree->dsa);\\n\\nMaybe better to have a header comment for RT_MEMORY_USAGE that the\\ncaller doesn't need to take a lock.\\n\\nv55-0006:\\n\\n\\\"WIP: Not built, since some benchmarks have broken\\\" -- I'll work on\\nthis when I re-run some benchmarks.\\n\\nv55-0007:\\n\\n+ * Internally, a tid is encoded as a pair of 64-bit key and 64-bit value,\\n+ * and stored in the radix tree.\\n\\nThis hasn't been true for a few months now, and I thought we fixed\\nthis in some earlier version?\\n\\n+ * TODO: The caller must be certain that no other backend will attempt to\\n+ * access the TidStore before calling this function. Other backend must\\n+ * explicitly call TidStoreDetach() to free up backend-local memory associated\\n+ * with the TidStore. The backend that calls TidStoreDestroy() must not call\\n+ * TidStoreDetach().\\n\\nDo we need to do anything now?\\n\\nv55-0008:\\n\\n-TidStoreAttach(dsa_area *area, TidStoreHandle handle)\\n+TidStoreAttach(dsa_area *area, dsa_pointer rt_dp)\\n\\n\\\"handle\\\" seemed like a fine name. Is that not the case anymore? The\\nnew one is kind of cryptic. The commit message just says \\\"remove\\ncontrol object\\\" -- does that imply that we need to think of this\\nparameter differently, or is it unrelated? (Same with\\ndead_items_handle in 0011)\\n\\nv55-0011:\\n\\n+ /*\\n+ * Recreate the tidstore with the same max_bytes limitation. We cannot\\n+ * use neither maintenance_work_mem nor autovacuum_work_mem as they could\\n+ * already be changed.\\n+ */\\n\\nI don't understand this part.\\n\\n\\n\",\n \"msg_date\": \"Wed, 24 Jan 2024 13:42:43 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 24, 2024 at 3:42 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 23, 2024 at 10:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > The new patches probably need to be polished but the VacDeadItemInfo\\n> > idea looks good to me.\\n>\\n> That idea looks good to me, too. Since you already likely know what\\n> you'd like to polish, I don't have much to say except for a few\\n> questions below. I also did a quick sweep through every patch, so some\\n> of these comments are unrelated to recent changes:\\n\\nThank you!\\n\\n>\\n> v55-0003:\\n>\\n> +size_t\\n> +dsa_get_total_size(dsa_area *area)\\n> +{\\n> + size_t size;\\n> +\\n> + LWLockAcquire(DSA_AREA_LOCK(area), LW_SHARED);\\n> + size = area->control->total_segment_size;\\n> + LWLockRelease(DSA_AREA_LOCK(area));\\n>\\n> I looked and found dsa.c doesn't already use shared locks in HEAD,\\n> even dsa_dump. Not sure why that is...\\n\\nOh, the dsa_dump part seems to be a bug. But it'll keep it consistent\\nwith others.\\n\\n>\\n> +/*\\n> + * Calculate the slab blocksize so that we can allocate at least 32 chunks\\n> + * from the block.\\n> + */\\n> +#define RT_SLAB_BLOCK_SIZE(size) \\\\\\n> + Max((SLAB_DEFAULT_BLOCK_SIZE / (size)) * (size), (size) * 32)\\n>\\n> The first parameter seems to be trying to make the block size exact,\\n> but that's not right, because of the chunk header, and maybe\\n> alignment. If the default block size is big enough to waste only a\\n> tiny amount of space, let's just use that as-is.\\n\\nAgreed.\\n\\n> Also, I think all\\n> block sizes in the code base have been a power of two, but I'm not\\n> sure how much that matters.\\n\\nDid you mean all slab block sizes we use in radixtree.h?\\n\\n>\\n> +#ifdef RT_SHMEM\\n> + fprintf(stderr, \\\" [%d] chunk %x slot \\\" DSA_POINTER_FORMAT \\\"\\\\n\\\",\\n> + i, n4->chunks[i], n4->children[i]);\\n> +#else\\n> + fprintf(stderr, \\\" [%d] chunk %x slot %p\\\\n\\\",\\n> + i, n4->chunks[i], n4->children[i]);\\n> +#endif\\n>\\n> Maybe we could invent a child pointer format, so we only #ifdef in one place.\\n\\nWIll change.\\n\\n>\\n> --- /dev/null\\n> +++ b/src/test/modules/test_radixtree/meson.build\\n> @@ -0,0 +1,35 @@\\n> +# FIXME: prevent install during main install, but not during test :/\\n>\\n> Can you look into this?\\n\\nOkay, I'll look at it.\\n\\n>\\n> test_radixtree.c:\\n>\\n> +/*\\n> + * XXX: should we expose and use RT_SIZE_CLASS and RT_SIZE_CLASS_INFO?\\n> + */\\n> +static int rt_node_class_fanouts[] = {\\n> + 4, /* RT_CLASS_3 */\\n> + 15, /* RT_CLASS_32_MIN */\\n> + 32, /* RT_CLASS_32_MAX */\\n> + 125, /* RT_CLASS_125 */\\n> + 256 /* RT_CLASS_256 */\\n> +};\\n>\\n> These numbers have been wrong a long time, too, but only matters for\\n> figuring out where it went wrong when something is broken. And for the\\n> XXX, instead of trying to use the largest number that should fit (it's\\n> obviously not testing that the expected node can actually hold that\\n> number anyway), it seems we can just use a \\\"big enough\\\" number to\\n> cause growing into the desired size class.\\n>\\n> As far as cleaning up the tests, I always wondered why these didn't\\n> use EXPECT_TRUE, EXPECT_FALSE, etc. as in Andres's prototype where\\n> where convenient, and leave comments above the tests. That seemed like\\n> a good idea to me -- was there a reason to have hand-written branches\\n> and elog messages everywhere?\\n\\nThe current test is based on test_integerset. I agree that we can\\nimprove it by using EXPECT_TRUE etc.\\n\\n>\\n> --- a/src/tools/pginclude/cpluspluscheck\\n> +++ b/src/tools/pginclude/cpluspluscheck\\n> @@ -101,6 +101,12 @@ do\\n> test \\\"$f\\\" = src/include/nodes/nodetags.h && continue\\n> test \\\"$f\\\" = src/backend/nodes/nodetags.h && continue\\n>\\n> + # radixtree_*_impl.h cannot be included standalone: they are just\\n> code fragments.\\n> + test \\\"$f\\\" = src/include/lib/radixtree_delete_impl.h && continue\\n> + test \\\"$f\\\" = src/include/lib/radixtree_insert_impl.h && continue\\n> + test \\\"$f\\\" = src/include/lib/radixtree_iter_impl.h && continue\\n> + test \\\"$f\\\" = src/include/lib/radixtree_search_impl.h && continue\\n>\\n> Ha! I'd forgotten about these -- they're long outdated.\\n\\nWill remove.\\n\\n>\\n> v55-0005:\\n>\\n> - * The radix tree is locked in shared mode during the iteration, so\\n> - * RT_END_ITERATE needs to be called when finished to release the lock.\\n> + * The caller needs to acquire a lock in shared mode during the iteration\\n> + * if necessary.\\n>\\n> \\\"need if necessary\\\" is maybe better phrased as \\\"is the caller's responsibility\\\"\\n\\nWill fix.\\n\\n>\\n> + /*\\n> + * We can rely on DSA_AREA_LOCK to get the total amount of DSA memory.\\n> + */\\n> total = dsa_get_total_size(tree->dsa);\\n>\\n> Maybe better to have a header comment for RT_MEMORY_USAGE that the\\n> caller doesn't need to take a lock.\\n\\nWill fix.\\n\\n>\\n> v55-0006:\\n>\\n> \\\"WIP: Not built, since some benchmarks have broken\\\" -- I'll work on\\n> this when I re-run some benchmarks.\\n\\nThanks!\\n\\n>\\n> v55-0007:\\n>\\n> + * Internally, a tid is encoded as a pair of 64-bit key and 64-bit value,\\n> + * and stored in the radix tree.\\n>\\n> This hasn't been true for a few months now, and I thought we fixed\\n> this in some earlier version?\\n\\nYeah, I'll fix it.\\n\\n>\\n> + * TODO: The caller must be certain that no other backend will attempt to\\n> + * access the TidStore before calling this function. Other backend must\\n> + * explicitly call TidStoreDetach() to free up backend-local memory associated\\n> + * with the TidStore. The backend that calls TidStoreDestroy() must not call\\n> + * TidStoreDetach().\\n>\\n> Do we need to do anything now?\\n\\nNo, will remove it.\\n\\n>\\n> v55-0008:\\n>\\n> -TidStoreAttach(dsa_area *area, TidStoreHandle handle)\\n> +TidStoreAttach(dsa_area *area, dsa_pointer rt_dp)\\n>\\n> \\\"handle\\\" seemed like a fine name. Is that not the case anymore? The\\n> new one is kind of cryptic. The commit message just says \\\"remove\\n> control object\\\" -- does that imply that we need to think of this\\n> parameter differently, or is it unrelated? (Same with\\n> dead_items_handle in 0011)\\n\\nSince it's actually just a radix tree's handle it was kind of\\nunnatural to me to use the same dsa_pointer as different handles. But\\nrethinking it, I agree \\\"handle\\\" is a fine name.\\n\\n>\\n> v55-0011:\\n>\\n> + /*\\n> + * Recreate the tidstore with the same max_bytes limitation. We cannot\\n> + * use neither maintenance_work_mem nor autovacuum_work_mem as they could\\n> + * already be changed.\\n> + */\\n>\\n> I don't understand this part.\\n\\nI wanted to mean that if maintenance_work_mem is changed and the\\nconfig file is reloaded, its value could no longer be the same as the\\none that we used when initializing the parallel vacuum. That's why we\\nneed to store max_bytes in the DSM. I'll rephrase it.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 26 Jan 2024 23:05:54 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Jan 26, 2024 at 11:05 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Jan 24, 2024 at 3:42 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Tue, Jan 23, 2024 at 10:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > The new patches probably need to be polished but the VacDeadItemInfo\\n> > > idea looks good to me.\\n> >\\n> > That idea looks good to me, too. Since you already likely know what\\n> > you'd like to polish, I don't have much to say except for a few\\n> > questions below. I also did a quick sweep through every patch, so some\\n> > of these comments are unrelated to recent changes:\\n>\\n> Thank you!\\n>\\n> >\\n> > +/*\\n> > + * Calculate the slab blocksize so that we can allocate at least 32 chunks\\n> > + * from the block.\\n> > + */\\n> > +#define RT_SLAB_BLOCK_SIZE(size) \\\\\\n> > + Max((SLAB_DEFAULT_BLOCK_SIZE / (size)) * (size), (size) * 32)\\n> >\\n> > The first parameter seems to be trying to make the block size exact,\\n> > but that's not right, because of the chunk header, and maybe\\n> > alignment. If the default block size is big enough to waste only a\\n> > tiny amount of space, let's just use that as-is.\\n>\\n> Agreed.\\n>\\n\\nAs of v55 patch, the sizes of each node class are:\\n\\n- node4: 40 bytes\\n- node16_lo: 168 bytes\\n- node16_hi: 296 bytes\\n- node48: 784 bytes\\n- node256: 2088 bytes\\n\\nIf we use SLAB_DEFAULT_BLOCK_SIZE (8kB) for each node class, we waste\\n(approximately):\\n\\n- node4: 32 bytes\\n- node16_lo: 128 bytes\\n- node16_hi: 200 bytes\\n- node48: 352 bytes\\n- node256: 1928 bytes\\n\\nWe might want to calculate a better slab block size for node256 at least.\\n\\n> >\\n> > + * TODO: The caller must be certain that no other backend will attempt to\\n> > + * access the TidStore before calling this function. Other backend must\\n> > + * explicitly call TidStoreDetach() to free up backend-local memory associated\\n> > + * with the TidStore. The backend that calls TidStoreDestroy() must not call\\n> > + * TidStoreDetach().\\n> >\\n> > Do we need to do anything now?\\n>\\n> No, will remove it.\\n>\\n\\nI misunderstood something. I think the above statement is still true\\nbut we don't need to do anything at this stage. It's a typical usage\\nthat the leader destroys the shared data after confirming all workers\\nare detached. It's not a TODO but probably a NOTE.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jan 2024 16:29:10 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 29, 2024 at 2:29 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> > > +/*\\n> > > + * Calculate the slab blocksize so that we can allocate at least 32 chunks\\n> > > + * from the block.\\n> > > + */\\n> > > +#define RT_SLAB_BLOCK_SIZE(size) \\\\\\n> > > + Max((SLAB_DEFAULT_BLOCK_SIZE / (size)) * (size), (size) * 32)\\n> > >\\n> > > The first parameter seems to be trying to make the block size exact,\\n> > > but that's not right, because of the chunk header, and maybe\\n> > > alignment. If the default block size is big enough to waste only a\\n> > > tiny amount of space, let's just use that as-is.\\n\\n> If we use SLAB_DEFAULT_BLOCK_SIZE (8kB) for each node class, we waste\\n> [snip]\\n> We might want to calculate a better slab block size for node256 at least.\\n\\nI meant the macro could probably be\\n\\nMax(SLAB_DEFAULT_BLOCK_SIZE, (size) * N)\\n\\n(Right now N=32). I also realize I didn't answer your question earlier\\nabout block sizes being powers of two. I was talking about PG in\\ngeneral -- I was thinking all block sizes were powers of two. If\\nthat's true, I'm not sure if it's because programmers find the macro\\ncalculations easy to reason about, or if there was an implementation\\nreason for it (e.g. libc behavior). 32*2088 bytes is about 65kB, or\\njust above a power of two, so if we did round that up it would be\\n128kB.\\n\\n> > > + * TODO: The caller must be certain that no other backend will attempt to\\n> > > + * access the TidStore before calling this function. Other backend must\\n> > > + * explicitly call TidStoreDetach() to free up backend-local memory associated\\n> > > + * with the TidStore. The backend that calls TidStoreDestroy() must not call\\n> > > + * TidStoreDetach().\\n> > >\\n> > > Do we need to do anything now?\\n> >\\n> > No, will remove it.\\n> >\\n>\\n> I misunderstood something. I think the above statement is still true\\n> but we don't need to do anything at this stage. It's a typical usage\\n> that the leader destroys the shared data after confirming all workers\\n> are detached. It's not a TODO but probably a NOTE.\\n\\nOkay.\\n\\n\\n\",\n \"msg_date\": \"Mon, 29 Jan 2024 18:48:27 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Jan 29, 2024 at 8:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Jan 29, 2024 at 2:29 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > > +/*\\n> > > > + * Calculate the slab blocksize so that we can allocate at least 32 chunks\\n> > > > + * from the block.\\n> > > > + */\\n> > > > +#define RT_SLAB_BLOCK_SIZE(size) \\\\\\n> > > > + Max((SLAB_DEFAULT_BLOCK_SIZE / (size)) * (size), (size) * 32)\\n> > > >\\n> > > > The first parameter seems to be trying to make the block size exact,\\n> > > > but that's not right, because of the chunk header, and maybe\\n> > > > alignment. If the default block size is big enough to waste only a\\n> > > > tiny amount of space, let's just use that as-is.\\n>\\n> > If we use SLAB_DEFAULT_BLOCK_SIZE (8kB) for each node class, we waste\\n> > [snip]\\n> > We might want to calculate a better slab block size for node256 at least.\\n>\\n> I meant the macro could probably be\\n>\\n> Max(SLAB_DEFAULT_BLOCK_SIZE, (size) * N)\\n>\\n> (Right now N=32). I also realize I didn't answer your question earlier\\n> about block sizes being powers of two. I was talking about PG in\\n> general -- I was thinking all block sizes were powers of two. If\\n> that's true, I'm not sure if it's because programmers find the macro\\n> calculations easy to reason about, or if there was an implementation\\n> reason for it (e.g. libc behavior). 32*2088 bytes is about 65kB, or\\n> just above a power of two, so if we did round that up it would be\\n> 128kB.\\n\\nThank you for your explanation. It might be better to follow other\\ncodes. Does the calculation below make sense to you?\\n\\nRT_SIZE_CLASS_ELEM size_class = RT_SIZE_CLASS_INFO[i];\\nSize inner_blocksize = SLAB_DEFAULT_BLOCK_SIZE;\\nwhile (inner_blocksize < 32 * size_class.allocsize)\\n inner_blocksize <<= 1;\\n\\nAs for the lock mode in dsa.c, I've posted a question[1].\\n\\nRegards,\\n\\n[1] https://www.postgresql.org/message-id/CAD21AoALgrU2sGWzgq%2B6G9X0ynqyVOjMR5_k4HgsGRWae1j%3DwQ%40mail.gmail.com\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 30 Jan 2024 09:55:35 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 30, 2024 at 7:56 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Jan 29, 2024 at 8:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > I meant the macro could probably be\\n> >\\n> > Max(SLAB_DEFAULT_BLOCK_SIZE, (size) * N)\\n> >\\n> > (Right now N=32). I also realize I didn't answer your question earlier\\n> > about block sizes being powers of two. I was talking about PG in\\n> > general -- I was thinking all block sizes were powers of two. If\\n> > that's true, I'm not sure if it's because programmers find the macro\\n> > calculations easy to reason about, or if there was an implementation\\n> > reason for it (e.g. libc behavior). 32*2088 bytes is about 65kB, or\\n> > just above a power of two, so if we did round that up it would be\\n> > 128kB.\\n>\\n> Thank you for your explanation. It might be better to follow other\\n> codes. Does the calculation below make sense to you?\\n>\\n> RT_SIZE_CLASS_ELEM size_class = RT_SIZE_CLASS_INFO[i];\\n> Size inner_blocksize = SLAB_DEFAULT_BLOCK_SIZE;\\n> while (inner_blocksize < 32 * size_class.allocsize)\\n> inner_blocksize <<= 1;\\n\\nIt does make sense, but we can do it more simply:\\n\\nMax(SLAB_DEFAULT_BLOCK_SIZE, pg_nextpower2_32(size * 32))\\n\\n\\n\",\n \"msg_date\": \"Tue, 30 Jan 2024 17:20:11 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Jan 30, 2024 at 7:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Jan 30, 2024 at 7:56 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Jan 29, 2024 at 8:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > I meant the macro could probably be\\n> > >\\n> > > Max(SLAB_DEFAULT_BLOCK_SIZE, (size) * N)\\n> > >\\n> > > (Right now N=32). I also realize I didn't answer your question earlier\\n> > > about block sizes being powers of two. I was talking about PG in\\n> > > general -- I was thinking all block sizes were powers of two. If\\n> > > that's true, I'm not sure if it's because programmers find the macro\\n> > > calculations easy to reason about, or if there was an implementation\\n> > > reason for it (e.g. libc behavior). 32*2088 bytes is about 65kB, or\\n> > > just above a power of two, so if we did round that up it would be\\n> > > 128kB.\\n> >\\n> > Thank you for your explanation. It might be better to follow other\\n> > codes. Does the calculation below make sense to you?\\n> >\\n> > RT_SIZE_CLASS_ELEM size_class = RT_SIZE_CLASS_INFO[i];\\n> > Size inner_blocksize = SLAB_DEFAULT_BLOCK_SIZE;\\n> > while (inner_blocksize < 32 * size_class.allocsize)\\n> > inner_blocksize <<= 1;\\n>\\n> It does make sense, but we can do it more simply:\\n>\\n> Max(SLAB_DEFAULT_BLOCK_SIZE, pg_nextpower2_32(size * 32))\\n\\nThanks!\\n\\nI've attached the new patch set (v56). I've squashed previous updates\\nand addressed review comments on v55 in separate patches. Here are the\\nupdate summary:\\n\\n0004: fix compiler warning caught by ci test.\\n0005-0008: address review comments on radix tree codes.\\n0009: cleanup #define and #undef\\n0010: use TEST_SHARED_RT macro for shared radix tree test. RT_SHMEM is\\nundefined after including radixtree.h so we should not use it in test\\ncode.\\n0013-0015: address review comments on tidstore codes.\\n0017-0018: address review comments on vacuum integration codes.\\n\\nLooking at overall changes, there are still XXX and TODO comments in\\nradixtree.h:\\n\\n---\\n * XXX There are 4 node kinds, and this should never be increased,\\n * for several reasons:\\n * 1. With 5 or more kinds, gcc tends to use a jump table for switch\\n * statements.\\n * 2. The 4 kinds can be represented with 2 bits, so we have the option\\n * in the future to tag the node pointer with the kind, even on\\n * platforms with 32-bit pointers. This might speed up node traversal\\n * in trees with highly random node kinds.\\n * 3. We can have multiple size classes per node kind.\\n\\nCan we just remove \\\"XXX\\\"?\\n\\n---\\n * WIP: notes about traditional radix tree trading off span vs height...\\n\\nAre you going to write it?\\n\\n---\\n#ifdef RT_SHMEM\\n/* WIP: do we really need this? */\\ntypedef dsa_pointer RT_HANDLE;\\n#endif\\n\\nI think it's worth having it.\\n\\n---\\n * WIP: The paper uses at most 64 for this node kind. \\\"isset\\\" happens to fit\\n * inside a single bitmapword on most platforms, so it's a good starting\\n * point. We can make it higher if we need to.\\n */\\n#define RT_FANOUT_48_MAX (RT_NODE_MAX_SLOTS / 4)\\n\\nAre you going to work something on this?\\n\\n---\\n /* WIP: We could go first to the higher node16 size class */\\n newnode = RT_ALLOC_NODE(tree, RT_NODE_KIND_16, RT_CLASS_16_LO);\\n\\nDoes it mean to go to RT_CLASS_16_HI and then further go to\\nRT_CLASS_16_LO upon further deletion?\\n\\n---\\n * TODO: The current locking mechanism is not optimized for high concurrency\\n * with mixed read-write workloads. In the future it might be worthwhile\\n * to replace it with the Optimistic Lock Coupling or ROWEX mentioned in\\n * the paper \\\"The ART of Practical Synchronization\\\" by the same authors as\\n * the ART paper, 2016.\\n\\nI think it's not TODO for now, but a future improvement. We can remove it.\\n\\n---\\n/* TODO: consider 5 with subclass 1 or 2. */\\n#define RT_FANOUT_4 4\\n\\nIs there something we need to do here?\\n\\n---\\n/*\\n * Return index of the chunk and slot arrays for inserting into the node,\\n * such that the chunk array remains ordered.\\n * TODO: Improve performance for non-SIMD platforms.\\n */\\n\\nAre you going to work on this?\\n\\n---\\n/* Delete the element at 'idx' */\\n/* TODO: replace slow memmove's */\\n\\nAre you going to work on this?\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 31 Jan 2024 14:49:21 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Jan 31, 2024 at 12:50 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> I've attached the new patch set (v56). I've squashed previous updates\\n> and addressed review comments on v55 in separate patches. Here are the\\n> update summary:\\n>\\n> 0004: fix compiler warning caught by ci test.\\n> 0005-0008: address review comments on radix tree codes.\\n> 0009: cleanup #define and #undef\\n> 0010: use TEST_SHARED_RT macro for shared radix tree test. RT_SHMEM is\\n> undefined after including radixtree.h so we should not use it in test\\n> code.\\n\\nGreat, thanks!\\n\\nI have a few questions and comments on v56, then I'll address yours\\nbelow with the attached v57, which is mostly cosmetic adjustments.\\n\\nv56-0003:\\n\\n(Looking closer at tests)\\n\\n+static const bool rt_test_stats = false;\\n\\nI'm thinking we should just remove everything that depends on this,\\nand keep this module entirely about correctness.\\n\\n+ for (int shift = 0; shift <= (64 - 8); shift += 8)\\n+ test_node_types(shift);\\n\\nI'm not sure what the test_node_types_* functions are testing that\\ntest_basic doesn't. They have a different, and confusing, way to stop\\nat every size class and check the keys/values. It seems we can replace\\nall that with two more calls (asc/desc) to test_basic, with the\\nmaximum level.\\n\\nIt's pretty hard to see what test_pattern() is doing, or why it's\\nuseful. I wonder if instead the test could use something like the\\nbenchmark where random integers are masked off. That seems simpler. I\\ncan work on that, but I'd like to hear your side about test_pattern().\\n\\nv56-0007:\\n\\n+ *\\n+ * Since we can rely on DSA_AREA_LOCK to get the total amount of DSA memory,\\n+ * the caller doesn't need to take a lock.\\n\\nMaybe something like \\\"Since dsa_get_total_size() does appropriate locking ...\\\"?\\n\\nv56-0008\\n\\nThanks, I like how the tests look now.\\n\\n-NOTICE: testing node 4 with height 0 and ascending keys\\n...\\n+NOTICE: testing node 1 with height 0 and ascending keys\\n\\nNow that the number is not intended to match a size class, \\\"node X\\\"\\nseems out of place. Maybe we could have a separate array with strings?\\n\\n+ 1, /* RT_CLASS_4 */\\n\\nThis should be more than one, so that the basic test still exercises\\npaths that shift elements around.\\n\\n+ 100, /* RT_CLASS_48 */\\n\\nThis node currently holds 64 for local memory.\\n\\n+ 255 /* RT_CLASS_256 */\\n\\nThis is the only one where we know exactly how many it can take, so\\nmay as well keep it at 256.\\n\\nv56-0012:\\n\\nThe test module for tidstore could use a few more comments.\\n\\nv56-0015:\\n\\n+typedef dsa_pointer TidStoreHandle;\\n+\\n\\n-TidStoreAttach(dsa_area *area, dsa_pointer rt_dp)\\n+TidStoreAttach(dsa_area *area, TidStoreHandle handle)\\n {\\n TidStore *ts;\\n+ dsa_pointer rt_dp = handle;\\n\\nMy earlier opinion was that \\\"handle\\\" was a nicer variable name, but\\nthis brings back the typedef and also keeps the variable name I didn't\\nlike, but pushes it down into the function. I'm a bit confused, so\\nI've kept these not-squashed for now.\\n\\n-----------------------------------------------------------------------------------\\n\\nNow, for v57:\\n\\n> Looking at overall changes, there are still XXX and TODO comments in\\n> radixtree.h:\\n\\nThat's fine, as long as it's intentional as a message to readers. That\\nsaid, we can get rid of some:\\n\\n> ---\\n> * XXX There are 4 node kinds, and this should never be increased,\\n> * for several reasons:\\n> * 1. With 5 or more kinds, gcc tends to use a jump table for switch\\n> * statements.\\n> * 2. The 4 kinds can be represented with 2 bits, so we have the option\\n> * in the future to tag the node pointer with the kind, even on\\n> * platforms with 32-bit pointers. This might speed up node traversal\\n> * in trees with highly random node kinds.\\n> * 3. We can have multiple size classes per node kind.\\n>\\n> Can we just remove \\\"XXX\\\"?\\n\\nHow about \\\"NOTE\\\"?\\n\\n> ---\\n> * WIP: notes about traditional radix tree trading off span vs height...\\n>\\n> Are you going to write it?\\n\\nYes, when I draft a rough commit message, (for next time).\\n\\n> ---\\n> #ifdef RT_SHMEM\\n> /* WIP: do we really need this? */\\n> typedef dsa_pointer RT_HANDLE;\\n> #endif\\n>\\n> I think it's worth having it.\\n\\nOkay, removed WIP in v57-0004.\\n\\n> ---\\n> * WIP: The paper uses at most 64 for this node kind. \\\"isset\\\" happens to fit\\n> * inside a single bitmapword on most platforms, so it's a good starting\\n> * point. We can make it higher if we need to.\\n> */\\n> #define RT_FANOUT_48_MAX (RT_NODE_MAX_SLOTS / 4)\\n>\\n> Are you going to work something on this?\\n\\nHard-coded 64 for readability, and changed this paragraph to explain\\nthe current rationale more clearly:\\n\\n\\\"The paper uses at most 64 for this node kind, and one advantage for us\\nis that \\\"isset\\\" is a single bitmapword on most platforms, rather than\\nan array, allowing the compiler to get rid of loops.\\\"\\n\\n> ---\\n> /* WIP: We could go first to the higher node16 size class */\\n> newnode = RT_ALLOC_NODE(tree, RT_NODE_KIND_16, RT_CLASS_16_LO);\\n>\\n> Does it mean to go to RT_CLASS_16_HI and then further go to\\n> RT_CLASS_16_LO upon further deletion?\\n\\nYes. It wouldn't be much work to make shrinking symmetrical with\\ngrowing (a good thing), but it's not essential so I haven't done it\\nyet.\\n\\n> ---\\n> * TODO: The current locking mechanism is not optimized for high concurrency\\n> * with mixed read-write workloads. In the future it might be worthwhile\\n> * to replace it with the Optimistic Lock Coupling or ROWEX mentioned in\\n> * the paper \\\"The ART of Practical Synchronization\\\" by the same authors as\\n> * the ART paper, 2016.\\n>\\n> I think it's not TODO for now, but a future improvement. We can remove it.\\n\\nIt _is_ a TODO, regardless of when it happens.\\n\\n> ---\\n> /* TODO: consider 5 with subclass 1 or 2. */\\n> #define RT_FANOUT_4 4\\n>\\n> Is there something we need to do here?\\n\\nChanged to:\\n\\n\\\"To save memory in trees with sparse keys, it would make sense to have two\\nsize classes for the smallest kind (perhaps a high class of 5 and a low class\\nof 2), but it would be more effective to utilize lazy expansion and\\npath compression.\\\"\\n\\n> ---\\n> /*\\n> * Return index of the chunk and slot arrays for inserting into the node,\\n> * such that the chunk array remains ordered.\\n> * TODO: Improve performance for non-SIMD platforms.\\n> */\\n>\\n> Are you going to work on this?\\n\\nA small step in v57-0010. I've found a way to kill two birds with one\\nstone, by first checking for the case that the keys are inserted in\\norder. This also helps the SIMD case because it must branch anyway to\\navoid bitscanning a zero bitfield. This moves the branch up and turns\\na mask into an assert, looking a bit nicer. I've removed the TODO, but\\nmaybe we should add it to the search_eq function.\\n\\n> ---\\n> /* Delete the element at 'idx' */\\n> /* TODO: replace slow memmove's */\\n>\\n> Are you going to work on this?\\n\\nDone in v57-0011.\\n\\nThe rest:\\nv57-0004 - 0008 should be self explanatory, but questions/pushback welcome.\\nv57-0009 - I'm thinking leaves don't need to be memset at all. The\\nvalue written should be entirely the caller's responsibility, it\\nseems.\\nv57-0013 - the bench module can be built locally again\\nv57-0016 - minor comment edits in tid store\\n\\nMy todo:\\n- benchmark tid store / vacuum again, since we haven't since varlen\\ntypes and removing unnecessary locks. I'm pretty sure there's an\\naccidental memset call that crept in there, but I'm running out of\\nsteam today.\\n- leftover comment etc work\",\n \"msg_date\": \"Fri, 2 Feb 2024 18:47:02 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Feb 2, 2024 at 8:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Jan 31, 2024 at 12:50 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > I've attached the new patch set (v56). I've squashed previous updates\\n> > and addressed review comments on v55 in separate patches. Here are the\\n> > update summary:\\n> >\\n> > 0004: fix compiler warning caught by ci test.\\n> > 0005-0008: address review comments on radix tree codes.\\n> > 0009: cleanup #define and #undef\\n> > 0010: use TEST_SHARED_RT macro for shared radix tree test. RT_SHMEM is\\n> > undefined after including radixtree.h so we should not use it in test\\n> > code.\\n>\\n> Great, thanks!\\n>\\n> I have a few questions and comments on v56, then I'll address yours\\n> below with the attached v57, which is mostly cosmetic adjustments.\\n\\nThank you for the comments! I've squashed previous updates and your changes.\\n\\n>\\n> v56-0003:\\n>\\n> (Looking closer at tests)\\n>\\n> +static const bool rt_test_stats = false;\\n>\\n> I'm thinking we should just remove everything that depends on this,\\n> and keep this module entirely about correctness.\\n\\nAgreed. Removed in 0006 patch.\\n\\n>\\n> + for (int shift = 0; shift <= (64 - 8); shift += 8)\\n> + test_node_types(shift);\\n>\\n> I'm not sure what the test_node_types_* functions are testing that\\n> test_basic doesn't. They have a different, and confusing, way to stop\\n> at every size class and check the keys/values. It seems we can replace\\n> all that with two more calls (asc/desc) to test_basic, with the\\n> maximum level.\\n\\nAgreed, addressed in 0007 patch.\\n\\n>\\n> It's pretty hard to see what test_pattern() is doing, or why it's\\n> useful. I wonder if instead the test could use something like the\\n> benchmark where random integers are masked off. That seems simpler. I\\n> can work on that, but I'd like to hear your side about test_pattern().\\n\\nYeah, test_pattern() is originally created for the integerset so it\\ndoesn't necessarily fit the radixtree. I agree to use some tests from\\nbenchmarks.\\n\\n>\\n> v56-0007:\\n>\\n> + *\\n> + * Since we can rely on DSA_AREA_LOCK to get the total amount of DSA memory,\\n> + * the caller doesn't need to take a lock.\\n>\\n> Maybe something like \\\"Since dsa_get_total_size() does appropriate locking ...\\\"?\\n\\nAgreed. Fixed in 0005 patch.\\n\\n>\\n> v56-0008\\n>\\n> Thanks, I like how the tests look now.\\n>\\n> -NOTICE: testing node 4 with height 0 and ascending keys\\n> ...\\n> +NOTICE: testing node 1 with height 0 and ascending keys\\n>\\n> Now that the number is not intended to match a size class, \\\"node X\\\"\\n> seems out of place. Maybe we could have a separate array with strings?\\n>\\n> + 1, /* RT_CLASS_4 */\\n>\\n> This should be more than one, so that the basic test still exercises\\n> paths that shift elements around.\\n>\\n> + 100, /* RT_CLASS_48 */\\n>\\n> This node currently holds 64 for local memory.\\n>\\n> + 255 /* RT_CLASS_256 */\\n>\\n> This is the only one where we know exactly how many it can take, so\\n> may as well keep it at 256.\\n\\nFixed in 0008 patch.\\n\\n>\\n> v56-0012:\\n>\\n> The test module for tidstore could use a few more comments.\\n\\nAddressed in 0012 patch.\\n\\n>\\n> v56-0015:\\n>\\n> +typedef dsa_pointer TidStoreHandle;\\n> +\\n>\\n> -TidStoreAttach(dsa_area *area, dsa_pointer rt_dp)\\n> +TidStoreAttach(dsa_area *area, TidStoreHandle handle)\\n> {\\n> TidStore *ts;\\n> + dsa_pointer rt_dp = handle;\\n>\\n> My earlier opinion was that \\\"handle\\\" was a nicer variable name, but\\n> this brings back the typedef and also keeps the variable name I didn't\\n> like, but pushes it down into the function. I'm a bit confused, so\\n> I've kept these not-squashed for now.\\n\\nI misunderstood your comment. I've changed to use a variable name\\nrt_handle and removed the TidStoreHandle type. 0013 patch.\\n\\n>\\n> -----------------------------------------------------------------------------------\\n>\\n> Now, for v57:\\n>\\n> > Looking at overall changes, there are still XXX and TODO comments in\\n> > radixtree.h:\\n>\\n> That's fine, as long as it's intentional as a message to readers. That\\n> said, we can get rid of some:\\n>\\n> > ---\\n> > * XXX There are 4 node kinds, and this should never be increased,\\n> > * for several reasons:\\n> > * 1. With 5 or more kinds, gcc tends to use a jump table for switch\\n> > * statements.\\n> > * 2. The 4 kinds can be represented with 2 bits, so we have the option\\n> > * in the future to tag the node pointer with the kind, even on\\n> > * platforms with 32-bit pointers. This might speed up node traversal\\n> > * in trees with highly random node kinds.\\n> > * 3. We can have multiple size classes per node kind.\\n> >\\n> > Can we just remove \\\"XXX\\\"?\\n>\\n> How about \\\"NOTE\\\"?\\n\\nAgreed.\\n\\n>\\n> > ---\\n> > * WIP: notes about traditional radix tree trading off span vs height...\\n> >\\n> > Are you going to write it?\\n>\\n> Yes, when I draft a rough commit message, (for next time).\\n\\nThanks!\\n\\n>\\n> > ---\\n> > #ifdef RT_SHMEM\\n> > /* WIP: do we really need this? */\\n> > typedef dsa_pointer RT_HANDLE;\\n> > #endif\\n> >\\n> > I think it's worth having it.\\n>\\n> Okay, removed WIP in v57-0004.\\n>\\n> > ---\\n> > * WIP: The paper uses at most 64 for this node kind. \\\"isset\\\" happens to fit\\n> > * inside a single bitmapword on most platforms, so it's a good starting\\n> > * point. We can make it higher if we need to.\\n> > */\\n> > #define RT_FANOUT_48_MAX (RT_NODE_MAX_SLOTS / 4)\\n> >\\n> > Are you going to work something on this?\\n>\\n> Hard-coded 64 for readability, and changed this paragraph to explain\\n> the current rationale more clearly:\\n>\\n> \\\"The paper uses at most 64 for this node kind, and one advantage for us\\n> is that \\\"isset\\\" is a single bitmapword on most platforms, rather than\\n> an array, allowing the compiler to get rid of loops.\\\"\\n\\nLGTM.\\n\\n>\\n> > ---\\n> > /* WIP: We could go first to the higher node16 size class */\\n> > newnode = RT_ALLOC_NODE(tree, RT_NODE_KIND_16, RT_CLASS_16_LO);\\n> >\\n> > Does it mean to go to RT_CLASS_16_HI and then further go to\\n> > RT_CLASS_16_LO upon further deletion?\\n>\\n> Yes. It wouldn't be much work to make shrinking symmetrical with\\n> growing (a good thing), but it's not essential so I haven't done it\\n> yet.\\n\\nOkay, let's keep it as WIP.\\n\\n>\\n> > ---\\n> > * TODO: The current locking mechanism is not optimized for high concurrency\\n> > * with mixed read-write workloads. In the future it might be worthwhile\\n> > * to replace it with the Optimistic Lock Coupling or ROWEX mentioned in\\n> > * the paper \\\"The ART of Practical Synchronization\\\" by the same authors as\\n> > * the ART paper, 2016.\\n> >\\n> > I think it's not TODO for now, but a future improvement. We can remove it.\\n>\\n> It _is_ a TODO, regardless of when it happens.\\n\\nUnderstood.\\n\\n>\\n> > ---\\n> > /* TODO: consider 5 with subclass 1 or 2. */\\n> > #define RT_FANOUT_4 4\\n> >\\n> > Is there something we need to do here?\\n>\\n> Changed to:\\n>\\n> \\\"To save memory in trees with sparse keys, it would make sense to have two\\n> size classes for the smallest kind (perhaps a high class of 5 and a low class\\n> of 2), but it would be more effective to utilize lazy expansion and\\n> path compression.\\\"\\n\\nLGTM. But there is an extra '*' in the last line:\\n\\n+ /*\\n:\\n+ * of 2), but it would be more effective to utilize lazy expansion and\\n+ * path compression.\\n+ * */\\n\\nFixed in 0004 patch.\\n\\n>\\n> > ---\\n> > /*\\n> > * Return index of the chunk and slot arrays for inserting into the node,\\n> > * such that the chunk array remains ordered.\\n> > * TODO: Improve performance for non-SIMD platforms.\\n> > */\\n> >\\n> > Are you going to work on this?\\n>\\n> A small step in v57-0010. I've found a way to kill two birds with one\\n> stone, by first checking for the case that the keys are inserted in\\n> order. This also helps the SIMD case because it must branch anyway to\\n> avoid bitscanning a zero bitfield. This moves the branch up and turns\\n> a mask into an assert, looking a bit nicer. I've removed the TODO, but\\n> maybe we should add it to the search_eq function.\\n\\nGreat!\\n\\n>\\n> > ---\\n> > /* Delete the element at 'idx' */\\n> > /* TODO: replace slow memmove's */\\n> >\\n> > Are you going to work on this?\\n>\\n> Done in v57-0011.\\n\\nLGTM.\\n\\n>\\n> The rest:\\n> v57-0004 - 0008 should be self explanatory, but questions/pushback welcome.\\n> v57-0009 - I'm thinking leaves don't need to be memset at all. The\\n> value written should be entirely the caller's responsibility, it\\n> seems.\\n> v57-0013 - the bench module can be built locally again\\n> v57-0016 - minor comment edits in tid store\\n\\nThese fixes look good to me.\\n\\n>\\n> My todo:\\n> - benchmark tid store / vacuum again, since we haven't since varlen\\n> types and removing unnecessary locks. I'm pretty sure there's an\\n> accidental memset call that crept in there, but I'm running out of\\n> steam today.\\n> - leftover comment etc work\\n\\nThanks. I'm also going to do some benchmarks and tests.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 6 Feb 2024 11:57:58 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 6, 2024 at 9:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Feb 2, 2024 at 8:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > My todo:\\n> > - benchmark tid store / vacuum again, since we haven't since varlen\\n> > types and removing unnecessary locks.\\n\\nI ran a vacuum benchmark similar to the one in [1] (unlogged tables\\nfor reproducibility), but smaller tables (100 million records),\\ndeleting only the last 20% of the table, and including a parallel\\nvacuum test. Scripts attached.\\n\\nmonotonically ordered int column index:\\n\\nmaster:\\nsystem usage: CPU: user: 4.27 s, system: 0.41 s, elapsed: 4.70 s\\nsystem usage: CPU: user: 4.23 s, system: 0.44 s, elapsed: 4.69 s\\nsystem usage: CPU: user: 4.26 s, system: 0.39 s, elapsed: 4.66 s\\n\\nv-59:\\nsystem usage: CPU: user: 3.10 s, system: 0.44 s, elapsed: 3.56 s\\nsystem usage: CPU: user: 3.07 s, system: 0.35 s, elapsed: 3.43 s\\nsystem usage: CPU: user: 3.07 s, system: 0.36 s, elapsed: 3.44 s\\n\\nuuid column index:\\n\\nmaster:\\nsystem usage: CPU: user: 18.22 s, system: 1.70 s, elapsed: 20.01 s\\nsystem usage: CPU: user: 17.70 s, system: 1.70 s, elapsed: 19.48 s\\nsystem usage: CPU: user: 18.48 s, system: 1.59 s, elapsed: 20.43 s\\n\\nv-59:\\nsystem usage: CPU: user: 5.18 s, system: 1.18 s, elapsed: 6.45 s\\nsystem usage: CPU: user: 6.56 s, system: 1.39 s, elapsed: 7.99 s\\nsystem usage: CPU: user: 6.51 s, system: 1.44 s, elapsed: 8.05 s\\n\\nint & uuid indexes in parallel:\\n\\nmaster:\\nsystem usage: CPU: user: 4.53 s, system: 1.22 s, elapsed: 20.43 s\\nsystem usage: CPU: user: 4.49 s, system: 1.29 s, elapsed: 20.98 s\\nsystem usage: CPU: user: 4.46 s, system: 1.33 s, elapsed: 20.50 s\\n\\nv59:\\nsystem usage: CPU: user: 2.09 s, system: 0.32 s, elapsed: 4.86 s\\nsystem usage: CPU: user: 3.76 s, system: 0.51 s, elapsed: 8.92 s\\nsystem usage: CPU: user: 3.83 s, system: 0.54 s, elapsed: 9.09 s\\n\\nOver all, I'm pleased with these results, although I'm confused why\\nsometimes with the patch the first run reports running faster than the\\nothers. I'm curious what others get. Traversing a tree that lives in\\nDSA has some overhead, as expected, but still comes out way ahead of\\nmaster.\\n\\nThere are still some micro-benchmarks we could do on tidstore, and\\nit'd be good to find out worse-case memory use (1 dead tuple each on\\nspread-out pages), but this is decent demonstration.\\n\\n> > I'm not sure what the test_node_types_* functions are testing that\\n> > test_basic doesn't. They have a different, and confusing, way to stop\\n> > at every size class and check the keys/values. It seems we can replace\\n> > all that with two more calls (asc/desc) to test_basic, with the\\n> > maximum level.\\n\\nv58-0008:\\n\\n+ /* borrowed from RT_MAX_SHIFT */\\n+ const int max_shift = (pg_leftmost_one_pos64(UINT64_MAX) /\\nBITS_PER_BYTE) * BITS_PER_BYTE;\\n\\nThis is harder to read than \\\"64 - 8\\\", and doesn't really help\\nmaintainability either.\\nMaybe \\\"(sizeof(uint64) - 1) * BITS_PER_BYTE\\\" is a good compromise.\\n\\n+ /* leaf nodes */\\n+ test_basic(test_info, 0);\\n\\n+ /* internal nodes */\\n+ test_basic(test_info, 8);\\n+\\n+ /* max-level nodes */\\n+ test_basic(test_info, max_shift);\\n\\nThis three-way terminology is not very informative. How about:\\n\\n+ /* a tree with one level, i.e. a single node under the root node. */\\n ...\\n+ /* a tree with two levels */\\n ...\\n+ /* a tree with the maximum number of levels */\\n\\n+static void\\n+test_basic(rt_node_class_test_elem *test_info, int shift)\\n+{\\n+ elog(NOTICE, \\\"testing node %s with shift %d\\\", test_info->class_name, shift);\\n+\\n+ /* Test nodes while changing the key insertion order */\\n+ do_test_basic(test_info->nkeys, shift, false);\\n+ do_test_basic(test_info->nkeys, shift, true);\\n\\nAdding a level of indirection makes this harder to read, and do we\\nstill know whether a test failed in asc or desc keys?\\n\\n> > My earlier opinion was that \\\"handle\\\" was a nicer variable name, but\\n> > this brings back the typedef and also keeps the variable name I didn't\\n> > like, but pushes it down into the function. I'm a bit confused, so\\n> > I've kept these not-squashed for now.\\n>\\n> I misunderstood your comment. I've changed to use a variable name\\n> rt_handle and removed the TidStoreHandle type. 0013 patch.\\n\\n(diff against an earlier version)\\n- pvs->shared->dead_items_handle = TidStoreGetHandle(dead_items);\\n+ pvs->shared->dead_items_dp = TidStoreGetHandle(dead_items);\\n\\nShall we use \\\"handle\\\" in vacuum_parallel.c as well?\\n\\n> > I'm pretty sure there's an\\n> > accidental memset call that crept in there, but I'm running out of\\n> > steam today.\\n\\nI have just a little bit of work to add for v59:\\n\\nv59-0009 - set_offset_bitmap_at() will call memset if it needs to zero\\nany bitmapwords. That can only happen if e.g. there is an offset > 128\\nand there are none between 64 and 128, so not a huge deal but I think\\nit's a bit nicer in this patch.\\n\\n> > > * WIP: notes about traditional radix tree trading off span vs height...\\n> > >\\n> > > Are you going to write it?\\n> >\\n> > Yes, when I draft a rough commit message, (for next time).\\n\\nI haven't gotten to the commit message, but:\\n\\nv59-0004 - I did some rewriting of the top header comment to explain\\nART concepts for new readers, made small comment changes, and tidied\\nup some indentation that pgindent won't touch\\nv59-0005 - re-pgindent'ed\\n\\n\\n[1] https://www.postgresql.org/message-id/CAFBsxsHUxmXYy0y4RrhMcNe-R11Bm099Xe-wUdb78pOu0%2BPT2Q%40mail.gmail.com\",\n \"msg_date\": \"Sat, 10 Feb 2024 19:29:10 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sat, Feb 10, 2024 at 9:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Feb 6, 2024 at 9:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Feb 2, 2024 at 8:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > My todo:\\n> > > - benchmark tid store / vacuum again, since we haven't since varlen\\n> > > types and removing unnecessary locks.\\n>\\n> I ran a vacuum benchmark similar to the one in [1] (unlogged tables\\n> for reproducibility), but smaller tables (100 million records),\\n> deleting only the last 20% of the table, and including a parallel\\n> vacuum test. Scripts attached.\\n>\\n> monotonically ordered int column index:\\n>\\n> master:\\n> system usage: CPU: user: 4.27 s, system: 0.41 s, elapsed: 4.70 s\\n> system usage: CPU: user: 4.23 s, system: 0.44 s, elapsed: 4.69 s\\n> system usage: CPU: user: 4.26 s, system: 0.39 s, elapsed: 4.66 s\\n>\\n> v-59:\\n> system usage: CPU: user: 3.10 s, system: 0.44 s, elapsed: 3.56 s\\n> system usage: CPU: user: 3.07 s, system: 0.35 s, elapsed: 3.43 s\\n> system usage: CPU: user: 3.07 s, system: 0.36 s, elapsed: 3.44 s\\n>\\n> uuid column index:\\n>\\n> master:\\n> system usage: CPU: user: 18.22 s, system: 1.70 s, elapsed: 20.01 s\\n> system usage: CPU: user: 17.70 s, system: 1.70 s, elapsed: 19.48 s\\n> system usage: CPU: user: 18.48 s, system: 1.59 s, elapsed: 20.43 s\\n>\\n> v-59:\\n> system usage: CPU: user: 5.18 s, system: 1.18 s, elapsed: 6.45 s\\n> system usage: CPU: user: 6.56 s, system: 1.39 s, elapsed: 7.99 s\\n> system usage: CPU: user: 6.51 s, system: 1.44 s, elapsed: 8.05 s\\n>\\n> int & uuid indexes in parallel:\\n>\\n> master:\\n> system usage: CPU: user: 4.53 s, system: 1.22 s, elapsed: 20.43 s\\n> system usage: CPU: user: 4.49 s, system: 1.29 s, elapsed: 20.98 s\\n> system usage: CPU: user: 4.46 s, system: 1.33 s, elapsed: 20.50 s\\n>\\n> v59:\\n> system usage: CPU: user: 2.09 s, system: 0.32 s, elapsed: 4.86 s\\n> system usage: CPU: user: 3.76 s, system: 0.51 s, elapsed: 8.92 s\\n> system usage: CPU: user: 3.83 s, system: 0.54 s, elapsed: 9.09 s\\n>\\n> Over all, I'm pleased with these results, although I'm confused why\\n> sometimes with the patch the first run reports running faster than the\\n> others. I'm curious what others get. Traversing a tree that lives in\\n> DSA has some overhead, as expected, but still comes out way ahead of\\n> master.\\n\\nThanks! That's a great improvement.\\n\\nI've also run the same scripts in my environment just in case and got\\nsimilar results:\\n\\nmonotonically ordered int column index:\\n\\nmaster:\\nsystem usage: CPU: user: 14.81 s, system: 0.90 s, elapsed: 15.74 s\\nsystem usage: CPU: user: 14.91 s, system: 0.80 s, elapsed: 15.73 s\\nsystem usage: CPU: user: 14.85 s, system: 0.70 s, elapsed: 15.57 s\\n\\nv-59:\\nsystem usage: CPU: user: 9.47 s, system: 1.04 s, elapsed: 10.53 s\\nsystem usage: CPU: user: 9.67 s, system: 0.81 s, elapsed: 10.50 s\\nsystem usage: CPU: user: 9.59 s, system: 0.86 s, elapsed: 10.47 s\\n\\nuuid column index:\\n\\nmaster:\\nsystem usage: CPU: user: 28.37 s, system: 1.38 s, elapsed: 29.81 s\\nsystem usage: CPU: user: 28.05 s, system: 1.37 s, elapsed: 29.47 s\\nsystem usage: CPU: user: 28.46 s, system: 1.36 s, elapsed: 29.88 s\\n\\nv-59:\\nsystem usage: CPU: user: 14.87 s, system: 1.13 s, elapsed: 16.02 s\\nsystem usage: CPU: user: 14.84 s, system: 1.31 s, elapsed: 16.18 s\\nsystem usage: CPU: user: 10.96 s, system: 1.24 s, elapsed: 12.22 s\\n\\nint & uuid indexes in parallel:\\n\\nmaster:\\nsystem usage: CPU: user: 15.81 s, system: 1.43 s, elapsed: 34.31 s\\nsystem usage: CPU: user: 15.84 s, system: 1.41 s, elapsed: 34.34 s\\nsystem usage: CPU: user: 15.92 s, system: 1.39 s, elapsed: 34.33 s\\n\\nv-59:\\nsystem usage: CPU: user: 10.93 s, system: 0.92 s, elapsed: 17.59 s\\nsystem usage: CPU: user: 10.92 s, system: 1.20 s, elapsed: 17.58 s\\nsystem usage: CPU: user: 10.90 s, system: 1.01 s, elapsed: 17.45 s\\n\\n>\\n> There are still some micro-benchmarks we could do on tidstore, and\\n> it'd be good to find out worse-case memory use (1 dead tuple each on\\n> spread-out pages), but this is decent demonstration.\\n\\nI've tested a simple case where vacuum removes 33k dead tuples spread\\nabout every 10 pages.\\n\\nmaster:\\n198,000 bytes (=33000 * 6)\\nsystem usage: CPU: user: 29.49 s, system: 0.88 s, elapsed: 30.40 s\\n\\nv-59:\\n2,834,432 bytes (reported by TidStoreMemoryUsage())\\nsystem usage: CPU: user: 15.96 s, system: 0.89 s, elapsed: 16.88 s\\n\\n>\\n> > > I'm not sure what the test_node_types_* functions are testing that\\n> > > test_basic doesn't. They have a different, and confusing, way to stop\\n> > > at every size class and check the keys/values. It seems we can replace\\n> > > all that with two more calls (asc/desc) to test_basic, with the\\n> > > maximum level.\\n>\\n> v58-0008:\\n>\\n> + /* borrowed from RT_MAX_SHIFT */\\n> + const int max_shift = (pg_leftmost_one_pos64(UINT64_MAX) /\\n> BITS_PER_BYTE) * BITS_PER_BYTE;\\n>\\n> This is harder to read than \\\"64 - 8\\\", and doesn't really help\\n> maintainability either.\\n> Maybe \\\"(sizeof(uint64) - 1) * BITS_PER_BYTE\\\" is a good compromise.\\n>\\n> + /* leaf nodes */\\n> + test_basic(test_info, 0);\\n>\\n> + /* internal nodes */\\n> + test_basic(test_info, 8);\\n> +\\n> + /* max-level nodes */\\n> + test_basic(test_info, max_shift);\\n>\\n> This three-way terminology is not very informative. How about:\\n>\\n> + /* a tree with one level, i.e. a single node under the root node. */\\n> ...\\n> + /* a tree with two levels */\\n> ...\\n> + /* a tree with the maximum number of levels */\\n\\nAgreed.\\n\\n>\\n> +static void\\n> +test_basic(rt_node_class_test_elem *test_info, int shift)\\n> +{\\n> + elog(NOTICE, \\\"testing node %s with shift %d\\\", test_info->class_name, shift);\\n> +\\n> + /* Test nodes while changing the key insertion order */\\n> + do_test_basic(test_info->nkeys, shift, false);\\n> + do_test_basic(test_info->nkeys, shift, true);\\n>\\n> Adding a level of indirection makes this harder to read, and do we\\n> still know whether a test failed in asc or desc keys?\\n\\nAgreed, it seems to be better to keep the previous logging style.\\n\\n>\\n> > > My earlier opinion was that \\\"handle\\\" was a nicer variable name, but\\n> > > this brings back the typedef and also keeps the variable name I didn't\\n> > > like, but pushes it down into the function. I'm a bit confused, so\\n> > > I've kept these not-squashed for now.\\n> >\\n> > I misunderstood your comment. I've changed to use a variable name\\n> > rt_handle and removed the TidStoreHandle type. 0013 patch.\\n>\\n> (diff against an earlier version)\\n> - pvs->shared->dead_items_handle = TidStoreGetHandle(dead_items);\\n> + pvs->shared->dead_items_dp = TidStoreGetHandle(dead_items);\\n>\\n> Shall we use \\\"handle\\\" in vacuum_parallel.c as well?\\n\\nAgreed.\\n\\n>\\n> > > I'm pretty sure there's an\\n> > > accidental memset call that crept in there, but I'm running out of\\n> > > steam today.\\n>\\n> I have just a little bit of work to add for v59:\\n>\\n> v59-0009 - set_offset_bitmap_at() will call memset if it needs to zero\\n> any bitmapwords. That can only happen if e.g. there is an offset > 128\\n> and there are none between 64 and 128, so not a huge deal but I think\\n> it's a bit nicer in this patch.\\n\\nLGTM.\\n\\n>\\n> > > > * WIP: notes about traditional radix tree trading off span vs height...\\n> > > >\\n> > > > Are you going to write it?\\n> > >\\n> > > Yes, when I draft a rough commit message, (for next time).\\n>\\n> I haven't gotten to the commit message, but:\\n\\nI've drafted the commit message.\\n\\n>\\n> v59-0004 - I did some rewriting of the top header comment to explain\\n> ART concepts for new readers, made small comment changes, and tidied\\n> up some indentation that pgindent won't touch\\n> v59-0005 - re-pgindent'ed\\n\\nLGTM, squashed all changes.\\n\\nI've attached these updates from v59 in separate patches.\\n\\nI've run regression tests with valgrind and run the coverity scan, and\\nI don't see critical issues.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 15 Feb 2024 12:20:46 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Feb 15, 2024 at 10:21 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Sat, Feb 10, 2024 at 9:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> I've also run the same scripts in my environment just in case and got\\n> similar results:\\n\\nThanks for testing, looks good as well.\\n\\n> > There are still some micro-benchmarks we could do on tidstore, and\\n> > it'd be good to find out worse-case memory use (1 dead tuple each on\\n> > spread-out pages), but this is decent demonstration.\\n>\\n> I've tested a simple case where vacuum removes 33k dead tuples spread\\n> about every 10 pages.\\n>\\n> master:\\n> 198,000 bytes (=33000 * 6)\\n> system usage: CPU: user: 29.49 s, system: 0.88 s, elapsed: 30.40 s\\n>\\n> v-59:\\n> 2,834,432 bytes (reported by TidStoreMemoryUsage())\\n> system usage: CPU: user: 15.96 s, system: 0.89 s, elapsed: 16.88 s\\n\\nThe memory usage for the sparse case may be a concern, although it's\\nnot bad -- a multiple of something small is probably not huge in\\npractice. See below for an option we have for this.\\n\\n> > > > I'm pretty sure there's an\\n> > > > accidental memset call that crept in there, but I'm running out of\\n> > > > steam today.\\n> >\\n> > I have just a little bit of work to add for v59:\\n> >\\n> > v59-0009 - set_offset_bitmap_at() will call memset if it needs to zero\\n> > any bitmapwords. That can only happen if e.g. there is an offset > 128\\n> > and there are none between 64 and 128, so not a huge deal but I think\\n> > it's a bit nicer in this patch.\\n>\\n> LGTM.\\n\\nOkay, I've squashed this.\\n\\n> I've drafted the commit message.\\n\\nThanks, this is a good start.\\n\\n> I've run regression tests with valgrind and run the coverity scan, and\\n> I don't see critical issues.\\n\\nGreat!\\n\\nNow, I think we're in pretty good shape. There are a couple of things\\nthat might be objectionable, so I want to try to improve them in the\\nlittle time we have:\\n\\n1. Memory use for the sparse case. I shared an idea a few months ago\\nof how runtime-embeddable values (true combined pointer-value slots)\\ncould work for tids. I don't think this is a must-have, but it's not a\\nlot of code, and I have this working:\\n\\nv61-0006: Preparatory refactoring -- I think we should do this anyway,\\nsince the intent seems more clear to me.\\nv61-0007: Runtime-embeddable tids -- Optional for v17, but should\\nreduce memory regressions, so should be considered. Up to 3 tids can\\nbe stored in the last level child pointer. It's not polished, but I'll\\nonly proceed with that if we think we need this. \\\"flags\\\" iis called\\nthat because it could hold tidbitmap.c booleans (recheck, lossy) in\\nthe future, in addition to reserving space for the pointer tag. Note:\\nI hacked the tests to only have 2 offsets per block to demo, but of\\ncourse both paths should be tested.\\n\\n2. Management of memory contexts. It's pretty verbose and messy. I\\nthink the abstraction could be better:\\nA: tidstore currently passes CurrentMemoryContext to RT_CREATE, so we\\ncan't destroy or reset it. That means we have to do a lot of manual\\nwork.\\nB: Passing \\\"max_bytes\\\" to the radix tree was my idea, I believe, but\\nit seems the wrong responsibility. Not all uses will have a\\nwork_mem-type limit, I'm guessing. We only use it for limiting the max\\nblock size, and aset's default 8MB is already plenty small for\\nvacuum's large limit anyway. tidbitmap.c's limit is work_mem, so\\nsmaller, and there it makes sense to limit the max blocksize this way.\\nC: The context for values has complex #ifdefs based on the value\\nlength/varlen, but it's both too much and not enough. If we get a bump\\ncontext, how would we shoehorn that in for values for vacuum but not\\nfor tidbitmap?\\n\\nHere's an idea: Have vacuum (or tidbitmap etc.) pass a context to\\nTidStoreCreate(), and then to RT_CREATE. That context will contain the\\nvalues (for local mem), and the node slabs will be children of the\\nvalue context. That way, measuring memory usage and free-ing can just\\ncall with this parent context, and let recursion handle the rest.\\nPerhaps the passed context can also hold the radix-tree struct, but\\nI'm not sure since I haven't tried it. What do you think?\\n\\nWith this resolved, I think the radix tree is pretty close to\\ncommittable. The tid store will likely need some polish yet, but no\\nmajor issues I know of.\\n\\n(And, finally, a small thing I that I wanted to share just so I don't\\nforget, but maybe not worth the attention: In Andres's prototype,\\nthere is a comment wondering if an update can skip checking if it\\nfirst need to create a root node. This is pretty easy, and done in\\nv61-0008.)\",\n \"msg_date\": \"Thu, 15 Feb 2024 18:26:13 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"v61 had a brown-paper-bag bug in the embedded tids patch that didn't\\npresent in the tidstore test, but caused vacuum to fail, fixed in v62.\",\n \"msg_date\": \"Fri, 16 Feb 2024 07:51:39 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Feb 15, 2024 at 8:26 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Feb 15, 2024 at 10:21 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Sat, Feb 10, 2024 at 9:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > I've also run the same scripts in my environment just in case and got\\n> > similar results:\\n>\\n> Thanks for testing, looks good as well.\\n>\\n> > > There are still some micro-benchmarks we could do on tidstore, and\\n> > > it'd be good to find out worse-case memory use (1 dead tuple each on\\n> > > spread-out pages), but this is decent demonstration.\\n> >\\n> > I've tested a simple case where vacuum removes 33k dead tuples spread\\n> > about every 10 pages.\\n> >\\n> > master:\\n> > 198,000 bytes (=33000 * 6)\\n> > system usage: CPU: user: 29.49 s, system: 0.88 s, elapsed: 30.40 s\\n> >\\n> > v-59:\\n> > 2,834,432 bytes (reported by TidStoreMemoryUsage())\\n> > system usage: CPU: user: 15.96 s, system: 0.89 s, elapsed: 16.88 s\\n>\\n> The memory usage for the sparse case may be a concern, although it's\\n> not bad -- a multiple of something small is probably not huge in\\n> practice. See below for an option we have for this.\\n>\\n> > > > > I'm pretty sure there's an\\n> > > > > accidental memset call that crept in there, but I'm running out of\\n> > > > > steam today.\\n> > >\\n> > > I have just a little bit of work to add for v59:\\n> > >\\n> > > v59-0009 - set_offset_bitmap_at() will call memset if it needs to zero\\n> > > any bitmapwords. That can only happen if e.g. there is an offset > 128\\n> > > and there are none between 64 and 128, so not a huge deal but I think\\n> > > it's a bit nicer in this patch.\\n> >\\n> > LGTM.\\n>\\n> Okay, I've squashed this.\\n>\\n> > I've drafted the commit message.\\n>\\n> Thanks, this is a good start.\\n>\\n> > I've run regression tests with valgrind and run the coverity scan, and\\n> > I don't see critical issues.\\n>\\n> Great!\\n>\\n> Now, I think we're in pretty good shape. There are a couple of things\\n> that might be objectionable, so I want to try to improve them in the\\n> little time we have:\\n>\\n> 1. Memory use for the sparse case. I shared an idea a few months ago\\n> of how runtime-embeddable values (true combined pointer-value slots)\\n> could work for tids. I don't think this is a must-have, but it's not a\\n> lot of code, and I have this working:\\n>\\n> v61-0006: Preparatory refactoring -- I think we should do this anyway,\\n> since the intent seems more clear to me.\\n\\nLooks good refactoring to me.\\n\\n> v61-0007: Runtime-embeddable tids -- Optional for v17, but should\\n> reduce memory regressions, so should be considered. Up to 3 tids can\\n> be stored in the last level child pointer. It's not polished, but I'll\\n> only proceed with that if we think we need this. \\\"flags\\\" iis called\\n> that because it could hold tidbitmap.c booleans (recheck, lossy) in\\n> the future, in addition to reserving space for the pointer tag. Note:\\n> I hacked the tests to only have 2 offsets per block to demo, but of\\n> course both paths should be tested.\\n\\nInteresting. I've run the same benchmark tests we did[1][2] (the\\nmedian of 3 runs):\\n\\nmonotonically ordered int column index:\\n\\nmaster: system usage: CPU: user: 14.91 s, system: 0.80 s, elapsed: 15.73 s\\nv-59: system usage: CPU: user: 9.67 s, system: 0.81 s, elapsed: 10.50 s\\nv-62: system usage: CPU: user: 1.94 s, system: 0.69 s, elapsed: 2.64 s\\n\\nuuid column index:\\n\\nmaster: system usage: CPU: user: 28.37 s, system: 1.38 s, elapsed: 29.81 s\\nv-59: system usage: CPU: user: 14.84 s, system: 1.31 s, elapsed: 16.18 s\\nv-62: system usage: CPU: user: 4.06 s, system: 0.98 s, elapsed: 5.06 s\\n\\nint & uuid indexes in parallel:\\n\\nmaster: system usage: CPU: user: 15.92 s, system: 1.39 s, elapsed: 34.33 s\\nv-59: system usage: CPU: user: 10.92 s, system: 1.20 s, elapsed: 17.58 s\\nv-62: system usage: CPU: user: 2.54 s, system: 0.94 s, elapsed: 6.00 s\\n\\nsparse case:\\n\\nmaster:\\n198,000 bytes (=33000 * 6)\\nsystem usage: CPU: user: 29.49 s, system: 0.88 s, elapsed: 30.40 s\\n\\nv-59:\\n2,834,432 bytes (reported by TidStoreMemoryUsage())\\nsystem usage: CPU: user: 15.96 s, system: 0.89 s, elapsed: 16.88 s\\n\\nv-62:\\n729,088 bytes (reported by TidStoreMemoryUsage())\\nsystem usage: CPU: user: 4.63 s, system: 0.86 s, elapsed: 5.50 s\\n\\nI'm happy to see a huge improvement. While it's really fascinating to\\nme, I'm concerned about the time left until the feature freeze. We\\nneed to polish both tidstore and vacuum integration patches in 5\\nweeks. Personally I'd like to have it as a separate patch for now, and\\nfocus on completing the main three patches since we might face some\\nissues after pushing these patches. I think with 0007 patch it's a big\\nwin but it's still a win even without 0007 patch.\\n\\n>\\n> 2. Management of memory contexts. It's pretty verbose and messy. I\\n> think the abstraction could be better:\\n> A: tidstore currently passes CurrentMemoryContext to RT_CREATE, so we\\n> can't destroy or reset it. That means we have to do a lot of manual\\n> work.\\n> B: Passing \\\"max_bytes\\\" to the radix tree was my idea, I believe, but\\n> it seems the wrong responsibility. Not all uses will have a\\n> work_mem-type limit, I'm guessing. We only use it for limiting the max\\n> block size, and aset's default 8MB is already plenty small for\\n> vacuum's large limit anyway. tidbitmap.c's limit is work_mem, so\\n> smaller, and there it makes sense to limit the max blocksize this way.\\n> C: The context for values has complex #ifdefs based on the value\\n> length/varlen, but it's both too much and not enough. If we get a bump\\n> context, how would we shoehorn that in for values for vacuum but not\\n> for tidbitmap?\\n>\\n> Here's an idea: Have vacuum (or tidbitmap etc.) pass a context to\\n> TidStoreCreate(), and then to RT_CREATE. That context will contain the\\n> values (for local mem), and the node slabs will be children of the\\n> value context. That way, measuring memory usage and free-ing can just\\n> call with this parent context, and let recursion handle the rest.\\n> Perhaps the passed context can also hold the radix-tree struct, but\\n> I'm not sure since I haven't tried it. What do you think?\\n\\nIf I understand your idea correctly, RT_CREATE() creates the context\\nfor values as a child of the passed context and the node slabs as\\nchildren of the value context. That way, measuring memory usage can\\njust call with the value context. It sounds like a good idea. But it\\nwas not clear to me how to address point B and C.\\n\\nAnother variant of this idea would be that RT_CREATE() creates the\\nparent context of the value context to store radix-tree struct. That\\nis, the hierarchy would be like:\\n\\nA MemoryContext (passed by vacuum through tidstore)\\n - radix tree memory context (store radx-tree struct, control\\nstruct, and iterator)\\n - value context (aset, slab, or bump)\\n - node slab contexts\\n\\nFreeing can just call with the radix tree memory context. And perhaps\\nit works even if tidstore passes CurrentMemoryContex to RT_CREATE()?\\n\\n>\\n> With this resolved, I think the radix tree is pretty close to\\n> committable. The tid store will likely need some polish yet, but no\\n> major issues I know of.\\n\\nAgreed.\\n\\n>\\n> (And, finally, a small thing I that I wanted to share just so I don't\\n> forget, but maybe not worth the attention: In Andres's prototype,\\n> there is a comment wondering if an update can skip checking if it\\n> first need to create a root node. This is pretty easy, and done in\\n> v61-0008.)\\n\\nLGTM, thanks!\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 16 Feb 2024 12:04:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Feb 16, 2024 at 10:05 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > v61-0007: Runtime-embeddable tids -- Optional for v17, but should\\n> > reduce memory regressions, so should be considered. Up to 3 tids can\\n> > be stored in the last level child pointer. It's not polished, but I'll\\n> > only proceed with that if we think we need this. \\\"flags\\\" iis called\\n> > that because it could hold tidbitmap.c booleans (recheck, lossy) in\\n> > the future, in addition to reserving space for the pointer tag. Note:\\n> > I hacked the tests to only have 2 offsets per block to demo, but of\\n> > course both paths should be tested.\\n>\\n> Interesting. I've run the same benchmark tests we did[1][2] (the\\n> median of 3 runs):\\n>\\n> monotonically ordered int column index:\\n>\\n> master: system usage: CPU: user: 14.91 s, system: 0.80 s, elapsed: 15.73 s\\n> v-59: system usage: CPU: user: 9.67 s, system: 0.81 s, elapsed: 10.50 s\\n> v-62: system usage: CPU: user: 1.94 s, system: 0.69 s, elapsed: 2.64 s\\n\\nHmm, that's strange -- this test is intended to delete all records\\nfrom the last 20% of the blocks, so I wouldn't expect any improvement\\nhere, only in the sparse case. Maybe something is wrong. All the more\\nreason to put it off...\\n\\n> I'm happy to see a huge improvement. While it's really fascinating to\\n> me, I'm concerned about the time left until the feature freeze. We\\n> need to polish both tidstore and vacuum integration patches in 5\\n> weeks. Personally I'd like to have it as a separate patch for now, and\\n> focus on completing the main three patches since we might face some\\n> issues after pushing these patches. I think with 0007 patch it's a big\\n> win but it's still a win even without 0007 patch.\\n\\nAgreed to not consider it for initial commit. I'll hold on to it for\\nsome future time.\\n\\n> > 2. Management of memory contexts. It's pretty verbose and messy. I\\n> > think the abstraction could be better:\\n> > A: tidstore currently passes CurrentMemoryContext to RT_CREATE, so we\\n> > can't destroy or reset it. That means we have to do a lot of manual\\n> > work.\\n> > B: Passing \\\"max_bytes\\\" to the radix tree was my idea, I believe, but\\n> > it seems the wrong responsibility. Not all uses will have a\\n> > work_mem-type limit, I'm guessing. We only use it for limiting the max\\n> > block size, and aset's default 8MB is already plenty small for\\n> > vacuum's large limit anyway. tidbitmap.c's limit is work_mem, so\\n> > smaller, and there it makes sense to limit the max blocksize this way.\\n> > C: The context for values has complex #ifdefs based on the value\\n> > length/varlen, but it's both too much and not enough. If we get a bump\\n> > context, how would we shoehorn that in for values for vacuum but not\\n> > for tidbitmap?\\n> >\\n> > Here's an idea: Have vacuum (or tidbitmap etc.) pass a context to\\n> > TidStoreCreate(), and then to RT_CREATE. That context will contain the\\n> > values (for local mem), and the node slabs will be children of the\\n> > value context. That way, measuring memory usage and free-ing can just\\n> > call with this parent context, and let recursion handle the rest.\\n> > Perhaps the passed context can also hold the radix-tree struct, but\\n> > I'm not sure since I haven't tried it. What do you think?\\n>\\n> If I understand your idea correctly, RT_CREATE() creates the context\\n> for values as a child of the passed context and the node slabs as\\n> children of the value context. That way, measuring memory usage can\\n> just call with the value context. It sounds like a good idea. But it\\n> was not clear to me how to address point B and C.\\n\\nFor B & C, vacuum would create a context to pass to TidStoreCreate,\\nand it wouldn't need to bother changing max block size. RT_CREATE\\nwould use that directly for leaves (if any), and would only create\\nchild slab contexts under it. It would not need to know about\\nmax_bytes. Modifyng your diagram a bit, something like:\\n\\n- caller-supplied radix tree memory context (the 3 structs -- and\\nleaves, if any) (aset (or future bump?))\\n - node slab contexts\\n\\nThis might only be workable with aset, if we need to individually free\\nthe structs. (I haven't studied this, it was a recent idea)\\nIt's simpler, because with small fixed length values, we don't need to\\ndetect that and avoid creating a leaf context. All leaves would live\\nin the same context as the structs.\\n\\n> Another variant of this idea would be that RT_CREATE() creates the\\n> parent context of the value context to store radix-tree struct. That\\n> is, the hierarchy would be like:\\n>\\n> A MemoryContext (passed by vacuum through tidstore)\\n> - radix tree memory context (store radx-tree struct, control\\n> struct, and iterator)\\n> - value context (aset, slab, or bump)\\n> - node slab contexts\\n\\nThe template handling the value context here is complex, and is what I\\nmeant by 'C' above. Most fixed length allocations in all of the\\nbackend are aset, so it seems fine to use it always.\\n\\n> Freeing can just call with the radix tree memory context. And perhaps\\n> it works even if tidstore passes CurrentMemoryContex to RT_CREATE()?\\n\\nSeems like it would, but would keep some complexity, as I mentioned.\\n\\n\\n\",\n \"msg_date\": \"Fri, 16 Feb 2024 10:41:13 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Feb 16, 2024 at 12:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Feb 16, 2024 at 10:05 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > v61-0007: Runtime-embeddable tids -- Optional for v17, but should\\n> > > reduce memory regressions, so should be considered. Up to 3 tids can\\n> > > be stored in the last level child pointer. It's not polished, but I'll\\n> > > only proceed with that if we think we need this. \\\"flags\\\" iis called\\n> > > that because it could hold tidbitmap.c booleans (recheck, lossy) in\\n> > > the future, in addition to reserving space for the pointer tag. Note:\\n> > > I hacked the tests to only have 2 offsets per block to demo, but of\\n> > > course both paths should be tested.\\n> >\\n> > Interesting. I've run the same benchmark tests we did[1][2] (the\\n> > median of 3 runs):\\n> >\\n> > monotonically ordered int column index:\\n> >\\n> > master: system usage: CPU: user: 14.91 s, system: 0.80 s, elapsed: 15.73 s\\n> > v-59: system usage: CPU: user: 9.67 s, system: 0.81 s, elapsed: 10.50 s\\n> > v-62: system usage: CPU: user: 1.94 s, system: 0.69 s, elapsed: 2.64 s\\n>\\n> Hmm, that's strange -- this test is intended to delete all records\\n> from the last 20% of the blocks, so I wouldn't expect any improvement\\n> here, only in the sparse case. Maybe something is wrong. All the more\\n> reason to put it off...\\n\\nOkay, let's dig it deeper later.\\n\\n>\\n> > I'm happy to see a huge improvement. While it's really fascinating to\\n> > me, I'm concerned about the time left until the feature freeze. We\\n> > need to polish both tidstore and vacuum integration patches in 5\\n> > weeks. Personally I'd like to have it as a separate patch for now, and\\n> > focus on completing the main three patches since we might face some\\n> > issues after pushing these patches. I think with 0007 patch it's a big\\n> > win but it's still a win even without 0007 patch.\\n>\\n> Agreed to not consider it for initial commit. I'll hold on to it for\\n> some future time.\\n>\\n> > > 2. Management of memory contexts. It's pretty verbose and messy. I\\n> > > think the abstraction could be better:\\n> > > A: tidstore currently passes CurrentMemoryContext to RT_CREATE, so we\\n> > > can't destroy or reset it. That means we have to do a lot of manual\\n> > > work.\\n> > > B: Passing \\\"max_bytes\\\" to the radix tree was my idea, I believe, but\\n> > > it seems the wrong responsibility. Not all uses will have a\\n> > > work_mem-type limit, I'm guessing. We only use it for limiting the max\\n> > > block size, and aset's default 8MB is already plenty small for\\n> > > vacuum's large limit anyway. tidbitmap.c's limit is work_mem, so\\n> > > smaller, and there it makes sense to limit the max blocksize this way.\\n> > > C: The context for values has complex #ifdefs based on the value\\n> > > length/varlen, but it's both too much and not enough. If we get a bump\\n> > > context, how would we shoehorn that in for values for vacuum but not\\n> > > for tidbitmap?\\n> > >\\n> > > Here's an idea: Have vacuum (or tidbitmap etc.) pass a context to\\n> > > TidStoreCreate(), and then to RT_CREATE. That context will contain the\\n> > > values (for local mem), and the node slabs will be children of the\\n> > > value context. That way, measuring memory usage and free-ing can just\\n> > > call with this parent context, and let recursion handle the rest.\\n> > > Perhaps the passed context can also hold the radix-tree struct, but\\n> > > I'm not sure since I haven't tried it. What do you think?\\n> >\\n> > If I understand your idea correctly, RT_CREATE() creates the context\\n> > for values as a child of the passed context and the node slabs as\\n> > children of the value context. That way, measuring memory usage can\\n> > just call with the value context. It sounds like a good idea. But it\\n> > was not clear to me how to address point B and C.\\n>\\n> For B & C, vacuum would create a context to pass to TidStoreCreate,\\n> and it wouldn't need to bother changing max block size. RT_CREATE\\n> would use that directly for leaves (if any), and would only create\\n> child slab contexts under it. It would not need to know about\\n> max_bytes. Modifyng your diagram a bit, something like:\\n>\\n> - caller-supplied radix tree memory context (the 3 structs -- and\\n> leaves, if any) (aset (or future bump?))\\n> - node slab contexts\\n>\\n> This might only be workable with aset, if we need to individually free\\n> the structs. (I haven't studied this, it was a recent idea)\\n> It's simpler, because with small fixed length values, we don't need to\\n> detect that and avoid creating a leaf context. All leaves would live\\n> in the same context as the structs.\\n\\nThank you for the explanation.\\n\\nI think that vacuum and tidbitmap (and future users) would end up\\nhaving the same max block size calculation. And it seems slightly odd\\nlayering to me that max-block-size-specified context is created on\\nvacuum (or tidbitmap) layer, a varlen-value radix tree is created by\\ntidstore layer, and the passed context is used for leaves (if\\nvarlen-value is used) on radix tree layer. Another idea is to create a\\nmax-block-size-specified context on the tidstore layer. That is,\\nvacuum and tidbitmap pass a work_mem and a flag indicating whether the\\ntidstore can use the bump context, and tidstore creates a (aset of\\nbump) memory context with the calculated max block size and passes it\\nto the radix tree.\\n\\nAs for using the bump memory context, I feel that we need to store\\niterator struct in aset context at least as it can be individually\\nfreed and re-created. Or it might not be necessary to allocate the\\niterator struct in the same context as radix tree.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 19 Feb 2024 11:01:45 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 19, 2024 at 9:02 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I think that vacuum and tidbitmap (and future users) would end up\\n> having the same max block size calculation. And it seems slightly odd\\n> layering to me that max-block-size-specified context is created on\\n> vacuum (or tidbitmap) layer, a varlen-value radix tree is created by\\n> tidstore layer, and the passed context is used for leaves (if\\n> varlen-value is used) on radix tree layer.\\n\\nThat sounds slightly more complicated than I was thinking of, but we\\ncould actually be talking about the same thing: I'm drawing a\\ndistinction between \\\"used = must be detected / #ifdef'd\\\" and \\\"used =\\nactually happens to call allocation\\\". I meant that the passed context\\nwould _always_ be used for leaves, regardless of varlen or not. So\\nwith fixed-length values short enough to live in child pointer slots,\\nthat context would still be used for iteration etc.\\n\\n> Another idea is to create a\\n> max-block-size-specified context on the tidstore layer. That is,\\n> vacuum and tidbitmap pass a work_mem and a flag indicating whether the\\n> tidstore can use the bump context, and tidstore creates a (aset of\\n> bump) memory context with the calculated max block size and passes it\\n> to the radix tree.\\n\\nThat might be a better abstraction since both uses have some memory limit.\\n\\n> As for using the bump memory context, I feel that we need to store\\n> iterator struct in aset context at least as it can be individually\\n> freed and re-created. Or it might not be necessary to allocate the\\n> iterator struct in the same context as radix tree.\\n\\nOkay, that's one thing I was concerned about. Since we don't actually\\nhave a bump context yet, it seems simple to assume aset for non-nodes,\\nand if we do get it, we can adjust slightly. Anyway, this seems like a\\ngood thing to try to clean up, but it's also not a show-stopper.\\n\\nOn that note: I will be going on honeymoon shortly, and then to PGConf\\nIndia, so I will have sporadic connectivity for the next 10 days and\\nwon't be doing any hacking during that time.\\n\\nAndres, did you want to take a look at the radix tree patch 0003?\\nAside from the above possible cleanup, most of it should be stable.\\n\\n\\n\",\n \"msg_date\": \"Mon, 19 Feb 2024 17:47:15 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Feb 19, 2024 at 7:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Feb 19, 2024 at 9:02 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I think that vacuum and tidbitmap (and future users) would end up\\n> > having the same max block size calculation. And it seems slightly odd\\n> > layering to me that max-block-size-specified context is created on\\n> > vacuum (or tidbitmap) layer, a varlen-value radix tree is created by\\n> > tidstore layer, and the passed context is used for leaves (if\\n> > varlen-value is used) on radix tree layer.\\n>\\n> That sounds slightly more complicated than I was thinking of, but we\\n> could actually be talking about the same thing: I'm drawing a\\n> distinction between \\\"used = must be detected / #ifdef'd\\\" and \\\"used =\\n> actually happens to call allocation\\\". I meant that the passed context\\n> would _always_ be used for leaves, regardless of varlen or not. So\\n> with fixed-length values short enough to live in child pointer slots,\\n> that context would still be used for iteration etc.\\n>\\n> > Another idea is to create a\\n> > max-block-size-specified context on the tidstore layer. That is,\\n> > vacuum and tidbitmap pass a work_mem and a flag indicating whether the\\n> > tidstore can use the bump context, and tidstore creates a (aset of\\n> > bump) memory context with the calculated max block size and passes it\\n> > to the radix tree.\\n>\\n> That might be a better abstraction since both uses have some memory limit.\\n\\nI've drafted this idea, and fixed a bug in tidstore.c. Here is the\\nsummary of updates from v62:\\n\\n- removed v62-0007 patch as we discussed\\n- squashed v62-0006 and v62-0008 patches into 0003 patch\\n- v63-0008 patch fixes a bug in tidstore.\\n- v63-0009 patch is a draft idea of cleanup memory context handling.\\n\\n>\\n> > As for using the bump memory context, I feel that we need to store\\n> > iterator struct in aset context at least as it can be individually\\n> > freed and re-created. Or it might not be necessary to allocate the\\n> > iterator struct in the same context as radix tree.\\n>\\n> Okay, that's one thing I was concerned about. Since we don't actually\\n> have a bump context yet, it seems simple to assume aset for non-nodes,\\n> and if we do get it, we can adjust slightly. Anyway, this seems like a\\n> good thing to try to clean up, but it's also not a show-stopper.\\n>\\n> On that note: I will be going on honeymoon shortly, and then to PGConf\\n> India, so I will have sporadic connectivity for the next 10 days and\\n> won't be doing any hacking during that time.\\n\\nThank you for letting us know. Enjoy yourself!\\n\\nRegards\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 20 Feb 2024 15:59:04 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Feb 20, 2024 at 1:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> - v63-0008 patch fixes a bug in tidstore.\\n\\n- page->nwords = wordnum + 1;\\n- Assert(page->nwords = WORDS_PER_PAGE(offsets[num_offsets - 1]));\\n+ page->nwords = wordnum;\\n+ Assert(page->nwords == WORDS_PER_PAGE(offsets[num_offsets - 1]));\\n\\nYikes, I'm guessing this failed in a non-assert builds? I wonder why\\nmy compiler didn't yell at me... Have you tried a tidstore-debug build\\nwithout asserts?\\n\\n> - v63-0009 patch is a draft idea of cleanup memory context handling.\\n\\nThanks, looks pretty good!\\n\\n+ ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,\\n+ \\\"tidstore storage\\\",\\n\\n\\\"tidstore storage\\\" sounds a bit strange -- maybe look at some other\\ncontext names for ideas.\\n\\n- leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx, allocsize);\\n+ leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx != NULL\\n+ ? tree->leaf_ctx\\n+ : tree->context, allocsize);\\n\\nInstead of branching here, can we copy \\\"context\\\" to \\\"leaf_ctx\\\" when\\nnecessary (those names should look more like eachother, btw)? I think\\nthat means anything not covered by this case:\\n\\n+#ifndef RT_VARLEN_VALUE_SIZE\\n+ if (sizeof(RT_VALUE_TYPE) > sizeof(RT_PTR_ALLOC))\\n+ tree->leaf_ctx = SlabContextCreate(ctx,\\n+ RT_STR(RT_PREFIX) \\\"radix_tree leaf contex\\\",\\n+ RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n+ sizeof(RT_VALUE_TYPE));\\n+#endif /* !RT_VARLEN_VALUE_SIZE */\\n\\n...also, we should document why we're using slab here. On that, I\\ndon't recall why we are? We've never had a fixed-length type test case\\non 64-bit, so it wasn't because it won through benchmarking. It seems\\na hold-over from the days of \\\"multi-value leaves\\\". Is it to avoid the\\npossibility of space wastage with non-power-of-two size types?\\n\\nFor this stanza that remains unchanged:\\n\\nfor (int i = 0; i < RT_SIZE_CLASS_COUNT; i++)\\n{\\n MemoryContextDelete(tree->node_slabs[i]);\\n}\\n\\nif (tree->leaf_ctx)\\n{\\n MemoryContextDelete(tree->leaf_ctx);\\n}\\n\\n...is there a reason we can't just delete tree->ctx, and let that\\nrecursively delete child contexts?\\n\\nSecondly, I thought about my recent work to skip checking if we first\\nneed to create a root node, and that has a harmless (for vacuum at\\nleast) but slightly untidy behavior: When RT_SET is first called, and\\nthe key is bigger than 255, new nodes will go on top of the root node.\\nThese have chunk '0'. If all subsequent keys are big enough, the\\norginal root node will stay empty. If all keys are deleted, there will\\nbe a chain of empty nodes remaining. Again, I believe this is\\nharmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\ncall out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\non this, but likely not today.\\n\\nThirdly, cosmetic: With the introduction of single-value leaves, it\\nseems we should do s/RT_NODE_PTR/RT_CHILD_PTR/ -- what do you think?\\n\\n\\n\",\n \"msg_date\": \"Thu, 29 Feb 2024 18:43:39 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I'm looking at RT_FREE_RECURSE again (only used for DSA memory), and\\nI'm not convinced it's freeing all the memory. It's been many months\\nsince we discussed this last, but IIRC we cannot just tell DSA to free\\nall its segments, right? Is there currently anything preventing us\\nfrom destroying the whole DSA area at once?\\n\\n+ /* The last level node has pointers to values */\\n+ if (shift == 0)\\n+ {\\n+ dsa_free(tree->dsa, ptr);\\n+ return;\\n+ }\\n\\nIIUC, this doesn't actually free leaves, it only frees the last-level\\nnode. And, this function is unaware of whether children could be\\nembedded values. I'm thinking we need to get rid of the above\\npre-check and instead, each node kind to have something like (e.g.\\nnode4):\\n\\nRT_PTR_ALLOC child = n4->children[i];\\n\\nif (shift > 0)\\n RT_FREE_RECURSE(tree, child, shift - RT_SPAN);\\nelse if (!RT_CHILDPTR_IS_VALUE(child))\\n dsa_free(tree->dsa, child);\\n\\n...or am I missing something?\\n\\n\\n\",\n \"msg_date\": \"Fri, 1 Mar 2024 11:15:05 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I wrote:\\n\\n> Secondly, I thought about my recent work to skip checking if we first\\n> need to create a root node, and that has a harmless (for vacuum at\\n> least) but slightly untidy behavior: When RT_SET is first called, and\\n> the key is bigger than 255, new nodes will go on top of the root node.\\n> These have chunk '0'. If all subsequent keys are big enough, the\\n> orginal root node will stay empty. If all keys are deleted, there will\\n> be a chain of empty nodes remaining. Again, I believe this is\\n> harmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\n> call out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\n> on this, but likely not today.\\n\\nThis turns out to be a lot trickier than it looked, so it seems best\\nto allow a trivial amount of waste, as long as it's documented\\nsomewhere. It also wouldn't be terrible to re-add those branches,\\nsince they're highly predictable.\\n\\nI just noticed there are a lot of unused function parameters\\n(referring to parent slots) leftover from a few weeks ago. Those are\\nremoved in v64-0009. 0010 makes the obvious name change in those\\nremaining to \\\"parent_slot\\\". 0011 is a simplification in two places\\nregarding reserving slots. This should be a bit easier to read and\\npossibly makes it easier on the compiler.\",\n \"msg_date\": \"Fri, 1 Mar 2024 13:58:07 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Feb 29, 2024 at 8:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Feb 20, 2024 at 1:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > - v63-0008 patch fixes a bug in tidstore.\\n>\\n> - page->nwords = wordnum + 1;\\n> - Assert(page->nwords = WORDS_PER_PAGE(offsets[num_offsets - 1]));\\n> + page->nwords = wordnum;\\n> + Assert(page->nwords == WORDS_PER_PAGE(offsets[num_offsets - 1]));\\n>\\n> Yikes, I'm guessing this failed in a non-assert builds? I wonder why\\n> my compiler didn't yell at me... Have you tried a tidstore-debug build\\n> without asserts?\\n\\nYes. I didn't get any failures.\\n\\n>\\n> > - v63-0009 patch is a draft idea of cleanup memory context handling.\\n>\\n> Thanks, looks pretty good!\\n>\\n> + ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,\\n> + \\\"tidstore storage\\\",\\n>\\n> \\\"tidstore storage\\\" sounds a bit strange -- maybe look at some other\\n> context names for ideas.\\n\\nAgreed. How about \\\"tidstore's radix tree\\\"?\\n\\n>\\n> - leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx, allocsize);\\n> + leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx != NULL\\n> + ? tree->leaf_ctx\\n> + : tree->context, allocsize);\\n>\\n> Instead of branching here, can we copy \\\"context\\\" to \\\"leaf_ctx\\\" when\\n> necessary (those names should look more like eachother, btw)? I think\\n> that means anything not covered by this case:\\n>\\n> +#ifndef RT_VARLEN_VALUE_SIZE\\n> + if (sizeof(RT_VALUE_TYPE) > sizeof(RT_PTR_ALLOC))\\n> + tree->leaf_ctx = SlabContextCreate(ctx,\\n> + RT_STR(RT_PREFIX) \\\"radix_tree leaf contex\\\",\\n> + RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> + sizeof(RT_VALUE_TYPE));\\n> +#endif /* !RT_VARLEN_VALUE_SIZE */\\n>\\n> ...also, we should document why we're using slab here. On that, I\\n> don't recall why we are? We've never had a fixed-length type test case\\n> on 64-bit, so it wasn't because it won through benchmarking. It seems\\n> a hold-over from the days of \\\"multi-value leaves\\\". Is it to avoid the\\n> possibility of space wastage with non-power-of-two size types?\\n\\nYes, it matches my understanding.\\n\\n>\\n> For this stanza that remains unchanged:\\n>\\n> for (int i = 0; i < RT_SIZE_CLASS_COUNT; i++)\\n> {\\n> MemoryContextDelete(tree->node_slabs[i]);\\n> }\\n>\\n> if (tree->leaf_ctx)\\n> {\\n> MemoryContextDelete(tree->leaf_ctx);\\n> }\\n>\\n> ...is there a reason we can't just delete tree->ctx, and let that\\n> recursively delete child contexts?\\n\\nI thought that considering the RT_CREATE doesn't create its own memory\\ncontext but just uses the passed context, it might be a bit unusable\\nto delete the passed context in the radix tree code. For example, if a\\ncaller creates a radix tree (or tidstore) on a memory context and\\nwants to recreate it again and again, he also needs to re-create the\\nmemory context together. It might be okay if we leave comments on\\nRT_CREATE as a side effect, though. This is the same reason why we\\ndon't destroy tree->dsa in RT_FREE(). And, as for RT_FREE_RECURSE(),\\n\\nOn Fri, Mar 1, 2024 at 1:15 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I'm looking at RT_FREE_RECURSE again (only used for DSA memory), and\\n> I'm not convinced it's freeing all the memory. It's been many months\\n> since we discussed this last, but IIRC we cannot just tell DSA to free\\n> all its segments, right?\\n\\nRight.\\n\\n> Is there currently anything preventing us\\n> from destroying the whole DSA area at once?\\n\\nWhen it comes to tidstore and parallel vacuum, we initialize DSA and\\ncreate a tidstore there at the beginning of the lazy vacuum, and\\nrecreate the tidstore again after the heap vacuum. So I don't want to\\ndestroy the whole DSA when destroying the tidstore. Otherwise, we will\\nneed to create a new DSA and pass its handle somehow.\\n\\nProbably the bitmap scan case is similar. Given that bitmap scan\\n(re)creates tidbitmap in the same DSA multiple times, it's better to\\navoid freeing the whole DSA.\\n\\n>\\n> + /* The last level node has pointers to values */\\n> + if (shift == 0)\\n> + {\\n> + dsa_free(tree->dsa, ptr);\\n> + return;\\n> + }\\n>\\n> IIUC, this doesn't actually free leaves, it only frees the last-level\\n> node. And, this function is unaware of whether children could be\\n> embedded values. I'm thinking we need to get rid of the above\\n> pre-check and instead, each node kind to have something like (e.g.\\n> node4):\\n>\\n> RT_PTR_ALLOC child = n4->children[i];\\n>\\n> if (shift > 0)\\n> RT_FREE_RECURSE(tree, child, shift - RT_SPAN);\\n> else if (!RT_CHILDPTR_IS_VALUE(child))\\n> dsa_free(tree->dsa, child);\\n>\\n> ...or am I missing something?\\n\\nYou're not missing anything. RT_FREE_RECURSE() has not been updated\\nfor a long time. If we still need to use RT_FREE_RECURSE(), it should\\nbe updated.\\n\\n> Thirdly, cosmetic: With the introduction of single-value leaves, it\\n> seems we should do s/RT_NODE_PTR/RT_CHILD_PTR/ -- what do you think?\\n\\nAgreed.\\n\\nOn Fri, Mar 1, 2024 at 3:58 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I wrote:\\n>\\n> > Secondly, I thought about my recent work to skip checking if we first\\n> > need to create a root node, and that has a harmless (for vacuum at\\n> > least) but slightly untidy behavior: When RT_SET is first called, and\\n> > the key is bigger than 255, new nodes will go on top of the root node.\\n> > These have chunk '0'. If all subsequent keys are big enough, the\\n> > orginal root node will stay empty. If all keys are deleted, there will\\n> > be a chain of empty nodes remaining. Again, I believe this is\\n> > harmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\n> > call out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\n> > on this, but likely not today.\\n>\\n> This turns out to be a lot trickier than it looked, so it seems best\\n> to allow a trivial amount of waste, as long as it's documented\\n> somewhere. It also wouldn't be terrible to re-add those branches,\\n> since they're highly predictable.\\n>\\n> I just noticed there are a lot of unused function parameters\\n> (referring to parent slots) leftover from a few weeks ago. Those are\\n> removed in v64-0009. 0010 makes the obvious name change in those\\n> remaining to \\\"parent_slot\\\". 0011 is a simplification in two places\\n> regarding reserving slots. This should be a bit easier to read and\\n> possibly makes it easier on the compiler.\\n\\nThank you for the updates. I've briefly looked at these changes and\\nthey look good to me. I'm going to review them again in depth.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 1 Mar 2024 17:00:21 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 1, 2024 at 3:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Feb 29, 2024 at 8:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > + ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,\\n> > + \\\"tidstore storage\\\",\\n> >\\n> > \\\"tidstore storage\\\" sounds a bit strange -- maybe look at some other\\n> > context names for ideas.\\n>\\n> Agreed. How about \\\"tidstore's radix tree\\\"?\\n\\nThat might be okay. I'm now thinking \\\"TID storage\\\". On that note, one\\nimprovement needed when we polish tidstore.c is to make sure it's\\nspelled \\\"TID\\\" in comments, like other files do already.\\n\\n> > - leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx, allocsize);\\n> > + leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx != NULL\\n> > + ? tree->leaf_ctx\\n> > + : tree->context, allocsize);\\n> >\\n> > Instead of branching here, can we copy \\\"context\\\" to \\\"leaf_ctx\\\" when\\n> > necessary (those names should look more like eachother, btw)? I think\\n> > that means anything not covered by this case:\\n> >\\n> > +#ifndef RT_VARLEN_VALUE_SIZE\\n> > + if (sizeof(RT_VALUE_TYPE) > sizeof(RT_PTR_ALLOC))\\n> > + tree->leaf_ctx = SlabContextCreate(ctx,\\n> > + RT_STR(RT_PREFIX) \\\"radix_tree leaf contex\\\",\\n> > + RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> > + sizeof(RT_VALUE_TYPE));\\n> > +#endif /* !RT_VARLEN_VALUE_SIZE */\\n> >\\n> > ...also, we should document why we're using slab here. On that, I\\n> > don't recall why we are? We've never had a fixed-length type test case\\n> > on 64-bit, so it wasn't because it won through benchmarking. It seems\\n> > a hold-over from the days of \\\"multi-value leaves\\\". Is it to avoid the\\n> > possibility of space wastage with non-power-of-two size types?\\n>\\n> Yes, it matches my understanding.\\n\\nThere are two issues quoted here, so not sure if you mean both or only\\nthe last one...\\n\\nFor the latter, I'm not sure it makes sense to have code and #ifdef's\\nto force slab for large-enough fixed-length values just because we\\ncan. There may never be such a use-case anyway. I'm also not against\\nit, either, but it seems like a premature optimization.\\n\\n> > For this stanza that remains unchanged:\\n> >\\n> > for (int i = 0; i < RT_SIZE_CLASS_COUNT; i++)\\n> > {\\n> > MemoryContextDelete(tree->node_slabs[i]);\\n> > }\\n> >\\n> > if (tree->leaf_ctx)\\n> > {\\n> > MemoryContextDelete(tree->leaf_ctx);\\n> > }\\n> >\\n> > ...is there a reason we can't just delete tree->ctx, and let that\\n> > recursively delete child contexts?\\n>\\n> I thought that considering the RT_CREATE doesn't create its own memory\\n> context but just uses the passed context, it might be a bit unusable\\n> to delete the passed context in the radix tree code. For example, if a\\n> caller creates a radix tree (or tidstore) on a memory context and\\n> wants to recreate it again and again, he also needs to re-create the\\n> memory context together. It might be okay if we leave comments on\\n> RT_CREATE as a side effect, though. This is the same reason why we\\n> don't destroy tree->dsa in RT_FREE(). And, as for RT_FREE_RECURSE(),\\n\\nRight, I should have said \\\"reset\\\". Resetting a context will delete\\nit's children as well, and seems like it should work to reset the tree\\ncontext, and we don't have to know whether that context actually\\ncontains leaves at all. That should allow copying \\\"tree context\\\" to\\n\\\"leaf context\\\" in the case where we have no special context for\\nleaves.\\n\\n\\n\",\n \"msg_date\": \"Sun, 3 Mar 2024 12:43:05 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Mar 3, 2024 at 2:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Mar 1, 2024 at 3:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Feb 29, 2024 at 8:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > + ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,\\n> > > + \\\"tidstore storage\\\",\\n> > >\\n> > > \\\"tidstore storage\\\" sounds a bit strange -- maybe look at some other\\n> > > context names for ideas.\\n> >\\n> > Agreed. How about \\\"tidstore's radix tree\\\"?\\n>\\n> That might be okay. I'm now thinking \\\"TID storage\\\". On that note, one\\n> improvement needed when we polish tidstore.c is to make sure it's\\n> spelled \\\"TID\\\" in comments, like other files do already.\\n>\\n> > > - leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx, allocsize);\\n> > > + leaf.alloc = (RT_PTR_ALLOC) MemoryContextAlloc(tree->leaf_ctx != NULL\\n> > > + ? tree->leaf_ctx\\n> > > + : tree->context, allocsize);\\n> > >\\n> > > Instead of branching here, can we copy \\\"context\\\" to \\\"leaf_ctx\\\" when\\n> > > necessary (those names should look more like eachother, btw)? I think\\n> > > that means anything not covered by this case:\\n> > >\\n> > > +#ifndef RT_VARLEN_VALUE_SIZE\\n> > > + if (sizeof(RT_VALUE_TYPE) > sizeof(RT_PTR_ALLOC))\\n> > > + tree->leaf_ctx = SlabContextCreate(ctx,\\n> > > + RT_STR(RT_PREFIX) \\\"radix_tree leaf contex\\\",\\n> > > + RT_SLAB_BLOCK_SIZE(sizeof(RT_VALUE_TYPE)),\\n> > > + sizeof(RT_VALUE_TYPE));\\n> > > +#endif /* !RT_VARLEN_VALUE_SIZE */\\n> > >\\n> > > ...also, we should document why we're using slab here. On that, I\\n> > > don't recall why we are? We've never had a fixed-length type test case\\n> > > on 64-bit, so it wasn't because it won through benchmarking. It seems\\n> > > a hold-over from the days of \\\"multi-value leaves\\\". Is it to avoid the\\n> > > possibility of space wastage with non-power-of-two size types?\\n> >\\n> > Yes, it matches my understanding.\\n>\\n> There are two issues quoted here, so not sure if you mean both or only\\n> the last one...\\n\\nI meant only the last one.\\n\\n>\\n> For the latter, I'm not sure it makes sense to have code and #ifdef's\\n> to force slab for large-enough fixed-length values just because we\\n> can. There may never be such a use-case anyway. I'm also not against\\n> it, either, but it seems like a premature optimization.\\n\\nReading the old threads, the fact that using a slab context for leaves\\noriginally came from Andres's prototype patch, was to avoid rounding\\nup the bytes to a power of 2 number by aset.c. It makes sense to me to\\nuse a slab context for this case. To measure the effect of using a\\nslab, I've updated bench_radix_tree so it uses a large fixed-length\\nvalue. The struct I used is:\\n\\ntypedef struct mytype\\n{\\n uint64 a;\\n uint64 b;\\n uint64 c;\\n uint64 d;\\n char e[100];\\n} mytype;\\n\\nThe struct size is 136 bytes with padding, just above a power-of-2.\\nThe simple benchmark test showed using a slab context for leaves is\\nmore space efficient. The results are:\\n\\nslab:\\n= #select * from bench_load_random_int(1000000);\\n mem_allocated | load_ms\\n---------------+---------\\n 405643264 | 560\\n(1 row)\\n\\naset:\\n=# select * from bench_load_random_int(1000000);\\n mem_allocated | load_ms\\n---------------+---------\\n 527777792 | 576\\n(1 row)\\n\\n>\\n> > > For this stanza that remains unchanged:\\n> > >\\n> > > for (int i = 0; i < RT_SIZE_CLASS_COUNT; i++)\\n> > > {\\n> > > MemoryContextDelete(tree->node_slabs[i]);\\n> > > }\\n> > >\\n> > > if (tree->leaf_ctx)\\n> > > {\\n> > > MemoryContextDelete(tree->leaf_ctx);\\n> > > }\\n> > >\\n> > > ...is there a reason we can't just delete tree->ctx, and let that\\n> > > recursively delete child contexts?\\n> >\\n> > I thought that considering the RT_CREATE doesn't create its own memory\\n> > context but just uses the passed context, it might be a bit unusable\\n> > to delete the passed context in the radix tree code. For example, if a\\n> > caller creates a radix tree (or tidstore) on a memory context and\\n> > wants to recreate it again and again, he also needs to re-create the\\n> > memory context together. It might be okay if we leave comments on\\n> > RT_CREATE as a side effect, though. This is the same reason why we\\n> > don't destroy tree->dsa in RT_FREE(). And, as for RT_FREE_RECURSE(),\\n>\\n> Right, I should have said \\\"reset\\\". Resetting a context will delete\\n> it's children as well, and seems like it should work to reset the tree\\n> context, and we don't have to know whether that context actually\\n> contains leaves at all. That should allow copying \\\"tree context\\\" to\\n> \\\"leaf context\\\" in the case where we have no special context for\\n> leaves.\\n\\nResetting the tree->context seems to work. But I think we should note\\nfor callers that the dsa_area passed to RT_CREATE should be created in\\na different context than the context passed to RT_CREATE because\\notherwise RT_FREE() will also free the dsa_area. For example, the\\nfollowing code in test_radixtree.c will no longer work:\\n\\ndsa = dsa_create(tranche_id);\\nradixtree = rt_create(CurrentMemoryContext, dsa, tranche_id);\\n:\\nrt_free(radixtree);\\ndsa_detach(dsa); // dsa is already freed.\\n\\nSo I think that a practical usage of the radix tree will be that the\\ncaller creates a memory context for a radix tree and passes it to\\nRT_CREATE().\\n\\nI've attached an update patch set:\\n\\n- 0008 updates RT_FREE_RECURSE().\\n- 0009 patch is an updated version of cleanup radix tree memory handling.\\n- 0010 updates comments in tidstore.c such as replacing \\\"Tid\\\" with \\\"TID\\\".\\n- 0011 rename TidStore to TIDSTORE all places.\\n- 0012 update bench_radix_tree so it uses a (possibly large) struct\\ninstead of uint64.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 4 Mar 2024 15:05:12 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 4, 2024 at 1:05 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Sun, Mar 3, 2024 at 2:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > Right, I should have said \\\"reset\\\". Resetting a context will delete\\n> > it's children as well, and seems like it should work to reset the tree\\n> > context, and we don't have to know whether that context actually\\n> > contains leaves at all. That should allow copying \\\"tree context\\\" to\\n> > \\\"leaf context\\\" in the case where we have no special context for\\n> > leaves.\\n>\\n> Resetting the tree->context seems to work. But I think we should note\\n> for callers that the dsa_area passed to RT_CREATE should be created in\\n> a different context than the context passed to RT_CREATE because\\n> otherwise RT_FREE() will also free the dsa_area. For example, the\\n> following code in test_radixtree.c will no longer work:\\n>\\n> dsa = dsa_create(tranche_id);\\n> radixtree = rt_create(CurrentMemoryContext, dsa, tranche_id);\\n> :\\n> rt_free(radixtree);\\n> dsa_detach(dsa); // dsa is already freed.\\n>\\n> So I think that a practical usage of the radix tree will be that the\\n> caller creates a memory context for a radix tree and passes it to\\n> RT_CREATE().\\n\\nThat sounds workable to me.\\n\\n> I've attached an update patch set:\\n>\\n> - 0008 updates RT_FREE_RECURSE().\\n\\nThanks!\\n\\n> - 0009 patch is an updated version of cleanup radix tree memory handling.\\n\\nLooks pretty good, as does the rest. I'm going through again,\\nsquashing and making tiny adjustments to the template. The only thing\\nnot done is changing the test with many values to resemble the perf\\ntest more.\\n\\nI wrote:\\n> > Secondly, I thought about my recent work to skip checking if we first\\n> > need to create a root node, and that has a harmless (for vacuum at\\n> > least) but slightly untidy behavior: When RT_SET is first called, and\\n> > the key is bigger than 255, new nodes will go on top of the root node.\\n> > These have chunk '0'. If all subsequent keys are big enough, the\\n> > orginal root node will stay empty. If all keys are deleted, there will\\n> > be a chain of empty nodes remaining. Again, I believe this is\\n> > harmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\n> > call out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\n> > on this, but likely not today.\\n>\\n> This turns out to be a lot trickier than it looked, so it seems best\\n> to allow a trivial amount of waste, as long as it's documented\\n> somewhere. It also wouldn't be terrible to re-add those branches,\\n> since they're highly predictable.\\n\\nI put a little more work into this, and got it working, just needs a\\nsmall amount of finicky coding. I'll share tomorrow.\\n\\nI have a question about RT_FREE_RECURSE:\\n\\n+ check_stack_depth();\\n+ CHECK_FOR_INTERRUPTS();\\n\\nI'm not sure why these are here: The first seems overly paranoid,\\nalthough harmless, but the second is probably a bad idea. Why should\\nthe user be able to to interrupt the freeing of memory?\\n\\nAlso, I'm not quite happy that RT_ITER has a copy of a pointer to the\\ntree, leading to coding like \\\"iter->tree->ctl->root\\\". I *think* it\\nwould be easier to read if the tree was a parameter to these iteration\\nfunctions. That would require an API change, so the tests/tidstore\\nwould have some churn. I can do that, but before trying I wanted to\\nsee what you think -- is there some reason to keep the current way?\\n\\n\\n\",\n \"msg_date\": \"Mon, 4 Mar 2024 18:48:21 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 4, 2024 at 8:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Mar 4, 2024 at 1:05 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Sun, Mar 3, 2024 at 2:43 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > Right, I should have said \\\"reset\\\". Resetting a context will delete\\n> > > it's children as well, and seems like it should work to reset the tree\\n> > > context, and we don't have to know whether that context actually\\n> > > contains leaves at all. That should allow copying \\\"tree context\\\" to\\n> > > \\\"leaf context\\\" in the case where we have no special context for\\n> > > leaves.\\n> >\\n> > Resetting the tree->context seems to work. But I think we should note\\n> > for callers that the dsa_area passed to RT_CREATE should be created in\\n> > a different context than the context passed to RT_CREATE because\\n> > otherwise RT_FREE() will also free the dsa_area. For example, the\\n> > following code in test_radixtree.c will no longer work:\\n> >\\n> > dsa = dsa_create(tranche_id);\\n> > radixtree = rt_create(CurrentMemoryContext, dsa, tranche_id);\\n> > :\\n> > rt_free(radixtree);\\n> > dsa_detach(dsa); // dsa is already freed.\\n> >\\n> > So I think that a practical usage of the radix tree will be that the\\n> > caller creates a memory context for a radix tree and passes it to\\n> > RT_CREATE().\\n>\\n> That sounds workable to me.\\n>\\n> > I've attached an update patch set:\\n> >\\n> > - 0008 updates RT_FREE_RECURSE().\\n>\\n> Thanks!\\n>\\n> > - 0009 patch is an updated version of cleanup radix tree memory handling.\\n>\\n> Looks pretty good, as does the rest. I'm going through again,\\n> squashing and making tiny adjustments to the template. The only thing\\n> not done is changing the test with many values to resemble the perf\\n> test more.\\n>\\n> I wrote:\\n> > > Secondly, I thought about my recent work to skip checking if we first\\n> > > need to create a root node, and that has a harmless (for vacuum at\\n> > > least) but slightly untidy behavior: When RT_SET is first called, and\\n> > > the key is bigger than 255, new nodes will go on top of the root node.\\n> > > These have chunk '0'. If all subsequent keys are big enough, the\\n> > > orginal root node will stay empty. If all keys are deleted, there will\\n> > > be a chain of empty nodes remaining. Again, I believe this is\\n> > > harmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\n> > > call out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\n> > > on this, but likely not today.\\n> >\\n> > This turns out to be a lot trickier than it looked, so it seems best\\n> > to allow a trivial amount of waste, as long as it's documented\\n> > somewhere. It also wouldn't be terrible to re-add those branches,\\n> > since they're highly predictable.\\n>\\n> I put a little more work into this, and got it working, just needs a\\n> small amount of finicky coding. I'll share tomorrow.\\n>\\n> I have a question about RT_FREE_RECURSE:\\n>\\n> + check_stack_depth();\\n> + CHECK_FOR_INTERRUPTS();\\n>\\n> I'm not sure why these are here: The first seems overly paranoid,\\n> although harmless, but the second is probably a bad idea. Why should\\n> the user be able to to interrupt the freeing of memory?\\n\\nGood catch. We should not check the interruption there.\\n\\n> Also, I'm not quite happy that RT_ITER has a copy of a pointer to the\\n> tree, leading to coding like \\\"iter->tree->ctl->root\\\". I *think* it\\n> would be easier to read if the tree was a parameter to these iteration\\n> functions. That would require an API change, so the tests/tidstore\\n> would have some churn. I can do that, but before trying I wanted to\\n> see what you think -- is there some reason to keep the current way?\\n\\nI considered both usages, there are two reasons for the current style.\\nI'm concerned that if we pass both the tree and RT_ITER to iteration\\nfunctions, the caller could mistakenly pass a different tree than the\\none that was specified to create the RT_ITER. And the second reason is\\njust to make it consistent with other data structures such as\\ndynahash.c and dshash.c, but I now realized that in simplehash.h we\\npass both the hash table and the iterator.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Tue, 5 Mar 2024 10:27:21 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 5, 2024 at 8:27 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Mar 4, 2024 at 8:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 4, 2024 at 1:05 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> > > Resetting the tree->context seems to work. But I think we should note\\n> > > for callers that the dsa_area passed to RT_CREATE should be created in\\n> > > a different context than the context passed to RT_CREATE because\\n> > > otherwise RT_FREE() will also free the dsa_area. For example, the\\n> > > following code in test_radixtree.c will no longer work:\\n\\nI've added a comment in v66-0004, which contains a number of other\\nsmall corrections and edits.\\n\\nOn Fri, Mar 1, 2024 at 3:01 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > Thirdly, cosmetic: With the introduction of single-value leaves, it\\n> > seems we should do s/RT_NODE_PTR/RT_CHILD_PTR/ -- what do you think?\\n>\\n> Agreed.\\n\\nDone in v66-0005.\\n\\nv66-0006 removes outdated tests for invalid root that somehow got left over.\\n\\n> > I wrote:\\n> > > > Secondly, I thought about my recent work to skip checking if we first\\n> > > > need to create a root node, and that has a harmless (for vacuum at\\n> > > > least) but slightly untidy behavior: When RT_SET is first called, and\\n> > > > the key is bigger than 255, new nodes will go on top of the root node.\\n> > > > These have chunk '0'. If all subsequent keys are big enough, the\\n> > > > orginal root node will stay empty. If all keys are deleted, there will\\n> > > > be a chain of empty nodes remaining. Again, I believe this is\\n> > > > harmless, but to make tidy, it should easy to teach RT_EXTEND_UP to\\n> > > > call out to RT_EXTEND_DOWN if it finds the tree is empty. I can work\\n> > > > on this, but likely not today.\\n\\n> > I put a little more work into this, and got it working, just needs a\\n> > small amount of finicky coding. I'll share tomorrow.\\n\\nDone in v66-0007. I'm a bit disappointed in the extra messiness this\\nadds, although it's not a lot.\\n\\n> > + check_stack_depth();\\n> > + CHECK_FOR_INTERRUPTS();\\n> >\\n> > I'm not sure why these are here: The first seems overly paranoid,\\n> > although harmless, but the second is probably a bad idea. Why should\\n> > the user be able to to interrupt the freeing of memory?\\n>\\n> Good catch. We should not check the interruption there.\\n\\nRemoved in v66-0008.\\n\\n> > Also, I'm not quite happy that RT_ITER has a copy of a pointer to the\\n> > tree, leading to coding like \\\"iter->tree->ctl->root\\\". I *think* it\\n> > would be easier to read if the tree was a parameter to these iteration\\n> > functions. That would require an API change, so the tests/tidstore\\n> > would have some churn. I can do that, but before trying I wanted to\\n> > see what you think -- is there some reason to keep the current way?\\n>\\n> I considered both usages, there are two reasons for the current style.\\n> I'm concerned that if we pass both the tree and RT_ITER to iteration\\n> functions, the caller could mistakenly pass a different tree than the\\n> one that was specified to create the RT_ITER. And the second reason is\\n> just to make it consistent with other data structures such as\\n> dynahash.c and dshash.c, but I now realized that in simplehash.h we\\n> pass both the hash table and the iterator.\\n\\nOkay, then I don't think it's worth messing with at this point.\\n\\nOn Tue, Feb 6, 2024 at 9:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Feb 2, 2024 at 8:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > It's pretty hard to see what test_pattern() is doing, or why it's\\n> > useful. I wonder if instead the test could use something like the\\n> > benchmark where random integers are masked off. That seems simpler. I\\n> > can work on that, but I'd like to hear your side about test_pattern().\\n>\\n> Yeah, test_pattern() is originally created for the integerset so it\\n> doesn't necessarily fit the radixtree. I agree to use some tests from\\n> benchmarks.\\n\\nDone in v66-0009. I'd be curious to hear any feedback. I like the\\naspect that the random numbers come from a different seed every time\\nthe test runs.\\n\\nv66-0010/0011 run pgindent, the latter with one typedef added for the\\ntest module. 0012 - 0017 are copied from v65, and I haven't done any\\nwork on tidstore or vacuum, except for squashing most v65 follow-up\\npatches.\\n\\nI'd like to push 0001 and 0002 shortly, and then do another sweep over\\n0003, with remaining feedback, and get that in so we get some\\nbuildfarm testing before the remaining polishing work on\\ntidstore/vacuum.\",\n \"msg_date\": \"Tue, 5 Mar 2024 16:41:30 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 5, 2024 at 6:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Feb 6, 2024 at 9:58 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Feb 2, 2024 at 8:47 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > It's pretty hard to see what test_pattern() is doing, or why it's\\n> > > useful. I wonder if instead the test could use something like the\\n> > > benchmark where random integers are masked off. That seems simpler. I\\n> > > can work on that, but I'd like to hear your side about test_pattern().\\n> >\\n> > Yeah, test_pattern() is originally created for the integerset so it\\n> > doesn't necessarily fit the radixtree. I agree to use some tests from\\n> > benchmarks.\\n>\\n> Done in v66-0009. I'd be curious to hear any feedback. I like the\\n> aspect that the random numbers come from a different seed every time\\n> the test runs.\\n\\nThe new tests look good. Here are some comments:\\n\\n---\\n+ expected = keys[i];\\n+ iterval = rt_iterate_next(iter, &iterkey);\\n\\n- ndeleted++;\\n+ EXPECT_TRUE(iterval != NULL);\\n+ EXPECT_EQ_U64(iterkey, expected);\\n+ EXPECT_EQ_U64(*iterval, expected);\\n\\nCan we verify that the iteration returns keys in ascending order?\\n\\n---\\n+ /* reset random number generator for deletion */\\n+ pg_prng_seed(&state, seed);\\n\\nWhy is resetting the seed required here?\\n\\n---\\nThe radix tree (and dsa in TSET_SHARED_RT case) should be freed at the end.\\n\\n---\\n radixtree_ctx = AllocSetContextCreate(CurrentMemoryContext,\\n \\\"test_radix_tree\\\",\\n ALLOCSET_DEFAULT_SIZES);\\n\\nWe use a mix of ALLOCSET_DEFAULT_SIZES and ALLOCSET_SMALL_SIZES. I\\nthink it's better to use either one for consistency.\\n\\n> I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> 0003, with remaining feedback, and get that in so we get some\\n> buildfarm testing before the remaining polishing work on\\n> tidstore/vacuum.\\n\\nSounds a reasonable plan. 0001 and 0002 look good to me. I'm going to\\npolish tidstore and vacuum patches and update commit messages.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 01:11:43 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 5, 2024 at 11:12 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Tue, Mar 5, 2024 at 6:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > Done in v66-0009. I'd be curious to hear any feedback. I like the\\n> > aspect that the random numbers come from a different seed every time\\n> > the test runs.\\n>\\n> The new tests look good. Here are some comments:\\n>\\n> ---\\n> + expected = keys[i];\\n> + iterval = rt_iterate_next(iter, &iterkey);\\n>\\n> - ndeleted++;\\n> + EXPECT_TRUE(iterval != NULL);\\n> + EXPECT_EQ_U64(iterkey, expected);\\n> + EXPECT_EQ_U64(*iterval, expected);\\n>\\n> Can we verify that the iteration returns keys in ascending order?\\n\\nWe get the \\\"expected\\\" value from the keys we saved in the now-sorted\\narray, so we do already. Unless I misunderstand you.\\n\\n> ---\\n> + /* reset random number generator for deletion */\\n> + pg_prng_seed(&state, seed);\\n>\\n> Why is resetting the seed required here?\\n\\nGood catch - My intention was to delete in the same random order we\\ninserted with. We still have the keys in the array, but they're sorted\\nby now. I forgot to go the extra step and use the prng when generating\\nthe keys for deletion -- will fix.\\n\\n> ---\\n> The radix tree (and dsa in TSET_SHARED_RT case) should be freed at the end.\\n\\nWill fix.\\n\\n> ---\\n> radixtree_ctx = AllocSetContextCreate(CurrentMemoryContext,\\n> \\\"test_radix_tree\\\",\\n> ALLOCSET_DEFAULT_SIZES);\\n>\\n> We use a mix of ALLOCSET_DEFAULT_SIZES and ALLOCSET_SMALL_SIZES. I\\n> think it's better to use either one for consistency.\\n\\nWill change to \\\"small\\\", since 32-bit platforms will use slab for leaves.\\n\\nI'll look at the memory usage and estimate what 32-bit platforms will\\nuse, and maybe adjust the number of keys. A few megabytes is fine, but\\nnot many megabytes.\\n\\n> > I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> > 0003, with remaining feedback, and get that in so we get some\\n> > buildfarm testing before the remaining polishing work on\\n> > tidstore/vacuum.\\n>\\n> Sounds a reasonable plan. 0001 and 0002 look good to me. I'm going to\\n> polish tidstore and vacuum patches and update commit messages.\\n\\nSounds good.\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 10:59:34 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Mar 5, 2024 at 11:12 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Tue, Mar 5, 2024 at 6:41 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > Done in v66-0009. I'd be curious to hear any feedback. I like the\\n> > > aspect that the random numbers come from a different seed every time\\n> > > the test runs.\\n> >\\n> > The new tests look good. Here are some comments:\\n> >\\n> > ---\\n> > + expected = keys[i];\\n> > + iterval = rt_iterate_next(iter, &iterkey);\\n> >\\n> > - ndeleted++;\\n> > + EXPECT_TRUE(iterval != NULL);\\n> > + EXPECT_EQ_U64(iterkey, expected);\\n> > + EXPECT_EQ_U64(*iterval, expected);\\n> >\\n> > Can we verify that the iteration returns keys in ascending order?\\n>\\n> We get the \\\"expected\\\" value from the keys we saved in the now-sorted\\n> array, so we do already. Unless I misunderstand you.\\n\\nAh, you're right. Please ignore this comment.\\n\\n>\\n> > ---\\n> > radixtree_ctx = AllocSetContextCreate(CurrentMemoryContext,\\n> > \\\"test_radix_tree\\\",\\n> > ALLOCSET_DEFAULT_SIZES);\\n> >\\n> > We use a mix of ALLOCSET_DEFAULT_SIZES and ALLOCSET_SMALL_SIZES. I\\n> > think it's better to use either one for consistency.\\n>\\n> Will change to \\\"small\\\", since 32-bit platforms will use slab for leaves.\\n\\nAgreed.\\n\\n>\\n> I'll look at the memory usage and estimate what 32-bit platforms will\\n> use, and maybe adjust the number of keys. A few megabytes is fine, but\\n> not many megabytes.\\n\\nThanks, sounds good.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 15:45:22 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2024-03-05 16:41:30 +0700, John Naylor wrote:\\n> I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> 0003, with remaining feedback, and get that in so we get some\\n> buildfarm testing before the remaining polishing work on\\n> tidstore/vacuum.\\n\\nA few ARM buildfarm animals are complaining:\\n\\nhttps://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=parula&dt=2024-03-06%2007%3A34%3A02\\nhttps://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=snakefly&dt=2024-03-06%2007%3A34%3A03\\nhttps://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=massasauga&dt=2024-03-06%2007%3A33%3A18\\n\\nGreetings,\\n\\nAndres Freund\\n\\n\\n\",\n \"msg_date\": \"Tue, 5 Mar 2024 23:41:06 -0800\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 4:41 PM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> Hi,\\n>\\n> On 2024-03-05 16:41:30 +0700, John Naylor wrote:\\n> > I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> > 0003, with remaining feedback, and get that in so we get some\\n> > buildfarm testing before the remaining polishing work on\\n> > tidstore/vacuum.\\n>\\n> A few ARM buildfarm animals are complaining:\\n>\\n> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=parula&dt=2024-03-06%2007%3A34%3A02\\n> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=snakefly&dt=2024-03-06%2007%3A34%3A03\\n> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=massasauga&dt=2024-03-06%2007%3A33%3A18\\n>\\n\\nThe error message we got is:\\n\\n../../src/include/port/simd.h:326:71: error: incompatible type for\\nargument 1 of \\\\342\\\\200\\\\230vshrq_n_s8\\\\342\\\\200\\\\231\\n uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8(v, 7));\\n ^\\n\\nSince 'v' is uint8x16_t I think we should have used vshrq_n_u8() instead.\\n\\nRegard,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 17:02:17 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 3:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Mar 6, 2024 at 4:41 PM Andres Freund <andres@anarazel.de> wrote:\\n\\n> > A few ARM buildfarm animals are complaining:\\n> >\\n> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=parula&dt=2024-03-06%2007%3A34%3A02\\n> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=snakefly&dt=2024-03-06%2007%3A34%3A03\\n> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=massasauga&dt=2024-03-06%2007%3A33%3A18\\n> >\\n>\\n> The error message we got is:\\n>\\n> ../../src/include/port/simd.h:326:71: error: incompatible type for\\n> argument 1 of \\\\342\\\\200\\\\230vshrq_n_s8\\\\342\\\\200\\\\231\\n> uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8(v, 7));\\n> ^\\n>\\n> Since 'v' is uint8x16_t I think we should have used vshrq_n_u8() instead.\\n\\nThat sounds plausible, and I'll look further.\\n\\n(Hmm, I thought we had run this code on Arm already...)\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 15:06:50 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi, \\n\\nOn March 6, 2024 9:06:50 AM GMT+01:00, John Naylor <johncnaylorls@gmail.com> wrote:\\n>On Wed, Mar 6, 2024 at 3:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>>\\n>> On Wed, Mar 6, 2024 at 4:41 PM Andres Freund <andres@anarazel.de> wrote:\\n>\\n>> > A few ARM buildfarm animals are complaining:\\n>> >\\n>> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=parula&dt=2024-03-06%2007%3A34%3A02\\n>> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=snakefly&dt=2024-03-06%2007%3A34%3A03\\n>> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=massasauga&dt=2024-03-06%2007%3A33%3A18\\n>> >\\n>>\\n>> The error message we got is:\\n>>\\n>> ../../src/include/port/simd.h:326:71: error: incompatible type for\\n>> argument 1 of \\\\342\\\\200\\\\230vshrq_n_s8\\\\342\\\\200\\\\231\\n>> uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8(v, 7));\\n>> ^\\n>>\\n>> Since 'v' is uint8x16_t I think we should have used vshrq_n_u8() instead.\\n>\\n>That sounds plausible, and I'll look further.\\n>\\n>(Hmm, I thought we had run this code on Arm already...)\\n\\nPerhaps we should switch one of the CI jobs to ARM...\\n\\nAndres \\n\\n-- \\nSent from my Android device with K-9 Mail. Please excuse my brevity.\\n\\n\\n\",\n \"msg_date\": \"Wed, 06 Mar 2024 09:13:14 +0100\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 3:06 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> (Hmm, I thought we had run this code on Arm already...)\\n\\nCI MacOS uses Clang on aarch64, which has been working fine. The\\nfailing animals are on gcc 7.3...\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 15:22:50 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 3:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> ../../src/include/port/simd.h:326:71: error: incompatible type for\\n> argument 1 of \\\\342\\\\200\\\\230vshrq_n_s8\\\\342\\\\200\\\\231\\n> uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8(v, 7));\\n> ^\\n>\\n> Since 'v' is uint8x16_t I think we should have used vshrq_n_u8() instead.\\n\\nI've looked around and it seems clang is more lax on conversions.\\nSince it works fine for clang, I think we just need a cast here for\\ngcc. I've attached a blind attempt at a fix -- I'll apply shortly\\nunless someone happens to test and find it doesn't work.\",\n \"msg_date\": \"Wed, 6 Mar 2024 15:33:44 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 5:33 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Mar 6, 2024 at 3:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > ../../src/include/port/simd.h:326:71: error: incompatible type for\\n> > argument 1 of \\\\342\\\\200\\\\230vshrq_n_s8\\\\342\\\\200\\\\231\\n> > uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8(v, 7));\\n> > ^\\n> >\\n> > Since 'v' is uint8x16_t I think we should have used vshrq_n_u8() instead.\\n>\\n> I've looked around and it seems clang is more lax on conversions.\\n> Since it works fine for clang, I think we just need a cast here for\\n> gcc. I've attached a blind attempt at a fix -- I'll apply shortly\\n> unless someone happens to test and find it doesn't work.\\n\\nI've reproduced the same error on my raspberry pi, and confirmed the\\npatch fixes the error.\\n\\nMy previous idea was wrong. With my proposal, the regression test for\\nradix tree failed on my raspberry pi. On the other hand, with your\\npatch the tests passed.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 17:40:20 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 3:40 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Mar 6, 2024 at 5:33 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > I've looked around and it seems clang is more lax on conversions.\\n> > Since it works fine for clang, I think we just need a cast here for\\n> > gcc. I've attached a blind attempt at a fix -- I'll apply shortly\\n> > unless someone happens to test and find it doesn't work.\\n>\\n> I've reproduced the same error on my raspberry pi, and confirmed the\\n> patch fixes the error.\\n>\\n> My previous idea was wrong. With my proposal, the regression test for\\n> radix tree failed on my raspberry pi. On the other hand, with your\\n> patch the tests passed.\\n\\nPushed, and at least parula's green now, thanks for testing! And\\nthanks, Andres, for the ping!\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 16:10:35 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 5, 2024 at 11:12 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> > 0003, with remaining feedback, and get that in so we get some\\n> > buildfarm testing before the remaining polishing work on\\n> > tidstore/vacuum.\\n>\\n> Sounds a reasonable plan. 0001 and 0002 look good to me. I'm going to\\n> polish tidstore and vacuum patches and update commit messages.\\n\\nI don't think v66 got a CI run because of vacuumlazy.c bitrot, so I'm\\nattaching v67 which fixes that and has some small cosmetic adjustments\\nto the template. One functional change for debugging build is that\\nRT_STATS now prints out the number of leaves. I'll squash and push\\n0001 tomorrow morning unless there are further comments.\",\n \"msg_date\": \"Wed, 6 Mar 2024 18:20:35 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Actually, I forgot -- I had one more question: Masahiko, is there a\\nreason for this extra local variable, which uses the base type, rather\\nthan the typedef'd parameter?\\n\\n+RT_SCOPE RT_RADIX_TREE *\\n+RT_ATTACH(dsa_area *dsa, RT_HANDLE handle)\\n+{\\n+ RT_RADIX_TREE *tree;\\n+ dsa_pointer control;\\n+\\n+ tree = (RT_RADIX_TREE *) palloc0(sizeof(RT_RADIX_TREE));\\n+\\n+ /* Find the control object in shared memory */\\n+ control = handle;\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 18:25:21 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 8:25 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> Actually, I forgot -- I had one more question: Masahiko, is there a\\n> reason for this extra local variable, which uses the base type, rather\\n> than the typedef'd parameter?\\n>\\n> +RT_SCOPE RT_RADIX_TREE *\\n> +RT_ATTACH(dsa_area *dsa, RT_HANDLE handle)\\n> +{\\n> + RT_RADIX_TREE *tree;\\n> + dsa_pointer control;\\n> +\\n> + tree = (RT_RADIX_TREE *) palloc0(sizeof(RT_RADIX_TREE));\\n> +\\n> + /* Find the control object in shared memory */\\n> + control = handle;\\n\\nI think it's mostly because of readability; it makes clear that the\\nhandle should be castable to dsa_pointer and it's a control object. I\\nborrowed it from dshash_attach().\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 20:58:51 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 8:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Mar 5, 2024 at 11:12 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > I'd like to push 0001 and 0002 shortly, and then do another sweep over\\n> > > 0003, with remaining feedback, and get that in so we get some\\n> > > buildfarm testing before the remaining polishing work on\\n> > > tidstore/vacuum.\\n> >\\n> > Sounds a reasonable plan. 0001 and 0002 look good to me. I'm going to\\n> > polish tidstore and vacuum patches and update commit messages.\\n>\\n> I don't think v66 got a CI run because of vacuumlazy.c bitrot, so I'm\\n> attaching v67 which fixes that and has some small cosmetic adjustments\\n> to the template.\\n\\nThank you for updating the patch.\\n\\n> One functional change for debugging build is that\\n> RT_STATS now prints out the number of leaves. I'll squash and push\\n> 0001 tomorrow morning unless there are further comments.\\n\\nThe 0001 patch looks good to me. I have some minor comments:\\n\\n--- /dev/null\\n+++ b/src/test/modules/test_radixtree/Makefile\\n@@ -0,0 +1,23 @@\\n+# src/test/modules/test_radixtree/Makefile\\n+\\n+MODULE_big = test_radixtree\\n+OBJS = \\\\\\n+ $(WIN32RES) \\\\\\n+ test_radixtree.o\\n+PGFILEDESC = \\\"test_radixtree - test code for src/backend/lib/radixtree.c\\\"\\n+\\n\\n\\\"src/backend/lib/radixtree.c\\\" should be updated to\\n\\\"src/include/lib/radixtree.h\\\".\\n\\n---\\n--- /dev/null\\n+++ b/src/test/modules/test_radixtree/README\\n@@ -0,0 +1,7 @@\\n+test_integerset contains unit tests for testing the integer set implementation\\n+in src/backend/lib/integerset.c.\\n+\\n+The tests verify the correctness of the implementation, but they can also be\\n+used as a micro-benchmark. If you set the 'intset_test_stats' flag in\\n+test_integerset.c, the tests will print extra information about execution time\\n+and memory usage.\\n\\nThis file is not updated for test_radixtree. I think we can remove it\\nas the test cases in test_radixtree are clear.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 6 Mar 2024 23:13:17 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 6, 2024 at 6:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > + /* Find the control object in shared memory */\\n> > + control = handle;\\n>\\n> I think it's mostly because of readability; it makes clear that the\\n> handle should be castable to dsa_pointer and it's a control object. I\\n> borrowed it from dshash_attach().\\n\\nI find that a bit strange, but I went ahead and kept it.\\n\\n\\n\\nOn Wed, Mar 6, 2024 at 9:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> The 0001 patch looks good to me. I have some minor comments:\\n\\n> +PGFILEDESC = \\\"test_radixtree - test code for src/backend/lib/radixtree.c\\\"\\n> +\\n>\\n> \\\"src/backend/lib/radixtree.c\\\" should be updated to\\n> \\\"src/include/lib/radixtree.h\\\".\\n\\nDone.\\n\\n> --- /dev/null\\n> +++ b/src/test/modules/test_radixtree/README\\n> @@ -0,0 +1,7 @@\\n> +test_integerset contains unit tests for testing the integer set implementation\\n> +in src/backend/lib/integerset.c.\\n> +\\n> +The tests verify the correctness of the implementation, but they can also be\\n> +used as a micro-benchmark. If you set the 'intset_test_stats' flag in\\n> +test_integerset.c, the tests will print extra information about execution time\\n> +and memory usage.\\n>\\n> This file is not updated for test_radixtree. I think we can remove it\\n> as the test cases in test_radixtree are clear.\\n\\nDone. I pushed this with a few last-minute cosmetic adjustments. This\\nhas been a very long time coming, but we're finally in the home\\nstretch!\\n\\nAlready, I see sifaka doesn't like this, and I'm looking now...\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 12:55:22 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 12:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Mar 6, 2024 at 6:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > + /* Find the control object in shared memory */\\n> > > + control = handle;\\n> >\\n> > I think it's mostly because of readability; it makes clear that the\\n> > handle should be castable to dsa_pointer and it's a control object. I\\n> > borrowed it from dshash_attach().\\n>\\n> I find that a bit strange, but I went ahead and kept it.\\n>\\n>\\n>\\n> On Wed, Mar 6, 2024 at 9:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > The 0001 patch looks good to me. I have some minor comments:\\n>\\n> > +PGFILEDESC = \\\"test_radixtree - test code for src/backend/lib/radixtree.c\\\"\\n> > +\\n> >\\n> > \\\"src/backend/lib/radixtree.c\\\" should be updated to\\n> > \\\"src/include/lib/radixtree.h\\\".\\n>\\n> Done.\\n>\\n> > --- /dev/null\\n> > +++ b/src/test/modules/test_radixtree/README\\n> > @@ -0,0 +1,7 @@\\n> > +test_integerset contains unit tests for testing the integer set implementation\\n> > +in src/backend/lib/integerset.c.\\n> > +\\n> > +The tests verify the correctness of the implementation, but they can also be\\n> > +used as a micro-benchmark. If you set the 'intset_test_stats' flag in\\n> > +test_integerset.c, the tests will print extra information about execution time\\n> > +and memory usage.\\n> >\\n> > This file is not updated for test_radixtree. I think we can remove it\\n> > as the test cases in test_radixtree are clear.\\n>\\n> Done. I pushed this with a few last-minute cosmetic adjustments. This\\n> has been a very long time coming, but we're finally in the home\\n> stretch!\\n>\\n> Already, I see sifaka doesn't like this, and I'm looking now...\\n\\nIt's complaining that these forward declarations...\\n\\n/* generate forward declarations necessary to use the radix tree */\\n#ifdef RT_DECLARE\\n\\ntypedef struct RT_RADIX_TREE RT_RADIX_TREE;\\ntypedef struct RT_ITER RT_ITER;\\n\\n... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\nfeature [-Werror,-Wtypedef-redefinition]\\\"\\n\\nI'll look in the other templates to see if what they do.\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 12:59:03 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 12:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Wed, Mar 6, 2024 at 6:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > + /* Find the control object in shared memory */\\n> > > > + control = handle;\\n> > >\\n> > > I think it's mostly because of readability; it makes clear that the\\n> > > handle should be castable to dsa_pointer and it's a control object. I\\n> > > borrowed it from dshash_attach().\\n> >\\n> > I find that a bit strange, but I went ahead and kept it.\\n> >\\n> >\\n> >\\n> > On Wed, Mar 6, 2024 at 9:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > The 0001 patch looks good to me. I have some minor comments:\\n> >\\n> > > +PGFILEDESC = \\\"test_radixtree - test code for src/backend/lib/radixtree.c\\\"\\n> > > +\\n> > >\\n> > > \\\"src/backend/lib/radixtree.c\\\" should be updated to\\n> > > \\\"src/include/lib/radixtree.h\\\".\\n> >\\n> > Done.\\n> >\\n> > > --- /dev/null\\n> > > +++ b/src/test/modules/test_radixtree/README\\n> > > @@ -0,0 +1,7 @@\\n> > > +test_integerset contains unit tests for testing the integer set implementation\\n> > > +in src/backend/lib/integerset.c.\\n> > > +\\n> > > +The tests verify the correctness of the implementation, but they can also be\\n> > > +used as a micro-benchmark. If you set the 'intset_test_stats' flag in\\n> > > +test_integerset.c, the tests will print extra information about execution time\\n> > > +and memory usage.\\n> > >\\n> > > This file is not updated for test_radixtree. I think we can remove it\\n> > > as the test cases in test_radixtree are clear.\\n> >\\n> > Done. I pushed this with a few last-minute cosmetic adjustments. This\\n> > has been a very long time coming, but we're finally in the home\\n> > stretch!\\n> >\\n> > Already, I see sifaka doesn't like this, and I'm looking now...\\n>\\n> It's complaining that these forward declarations...\\n>\\n> /* generate forward declarations necessary to use the radix tree */\\n> #ifdef RT_DECLARE\\n>\\n> typedef struct RT_RADIX_TREE RT_RADIX_TREE;\\n> typedef struct RT_ITER RT_ITER;\\n>\\n> ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> feature [-Werror,-Wtypedef-redefinition]\\\"\\n>\\n> I'll look in the other templates to see if what they do.\\n\\nTheir \\\"declare\\\" sections have full typedefs. I found it works to leave\\nout the typedef for the \\\"define\\\" section, but I first want to\\nreproduce the build failure.\\n\\nIn addition, olingo and grassquit are showing different kinds of\\n\\\"AddressSanitizer: odr-violation\\\" errors, which I'm not sure what to\\nmake of -- example:\\n\\n==1862767==ERROR: AddressSanitizer: odr-violation (0x7fc257476b60):\\n [1] size=256 'pg_leftmost_one_pos'\\n/home/bf/bf-build/olingo/HEAD/pgsql.build/../pgsql/src/port/pg_bitutils.c:34\\n [2] size=256 'pg_leftmost_one_pos'\\n/home/bf/bf-build/olingo/HEAD/pgsql.build/../pgsql/src/port/pg_bitutils.c:34\\nThese globals were registered at these points:\\n [1]:\\n #0 0x563564b97bf6 in __asan_register_globals\\n(/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e2bf6)\\n(BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n #1 0x563564b98d1d in __asan_register_elf_globals\\n(/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e3d1d)\\n(BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n #2 0x7fc265c3fe3d in call_init elf/dl-init.c:74:3\\n #3 0x7fc265c3fe3d in call_init elf/dl-init.c:26:1\\n\\n [2]:\\n #0 0x563564b97bf6 in __asan_register_globals\\n(/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e2bf6)\\n(BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n #1 0x563564b98d1d in __asan_register_elf_globals\\n(/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e3d1d)\\n(BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n #2 0x7fc2649847f5 in call_init csu/../csu/libc-start.c:145:3\\n #3 0x7fc2649847f5 in __libc_start_main csu/../csu/libc-start.c:347:5\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 13:19:46 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 12:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Wed, Mar 6, 2024 at 6:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > >\\n> > > > > + /* Find the control object in shared memory */\\n> > > > > + control = handle;\\n> > > >\\n> > > > I think it's mostly because of readability; it makes clear that the\\n> > > > handle should be castable to dsa_pointer and it's a control object. I\\n> > > > borrowed it from dshash_attach().\\n> > >\\n> > > I find that a bit strange, but I went ahead and kept it.\\n> > >\\n> > >\\n> > >\\n> > > On Wed, Mar 6, 2024 at 9:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > The 0001 patch looks good to me. I have some minor comments:\\n> > >\\n> > > > +PGFILEDESC = \\\"test_radixtree - test code for src/backend/lib/radixtree.c\\\"\\n> > > > +\\n> > > >\\n> > > > \\\"src/backend/lib/radixtree.c\\\" should be updated to\\n> > > > \\\"src/include/lib/radixtree.h\\\".\\n> > >\\n> > > Done.\\n> > >\\n> > > > --- /dev/null\\n> > > > +++ b/src/test/modules/test_radixtree/README\\n> > > > @@ -0,0 +1,7 @@\\n> > > > +test_integerset contains unit tests for testing the integer set implementation\\n> > > > +in src/backend/lib/integerset.c.\\n> > > > +\\n> > > > +The tests verify the correctness of the implementation, but they can also be\\n> > > > +used as a micro-benchmark. If you set the 'intset_test_stats' flag in\\n> > > > +test_integerset.c, the tests will print extra information about execution time\\n> > > > +and memory usage.\\n> > > >\\n> > > > This file is not updated for test_radixtree. I think we can remove it\\n> > > > as the test cases in test_radixtree are clear.\\n> > >\\n> > > Done. I pushed this with a few last-minute cosmetic adjustments. This\\n> > > has been a very long time coming, but we're finally in the home\\n> > > stretch!\\n> > >\\n> > > Already, I see sifaka doesn't like this, and I'm looking now...\\n> >\\n> > It's complaining that these forward declarations...\\n> >\\n> > /* generate forward declarations necessary to use the radix tree */\\n> > #ifdef RT_DECLARE\\n> >\\n> > typedef struct RT_RADIX_TREE RT_RADIX_TREE;\\n> > typedef struct RT_ITER RT_ITER;\\n> >\\n> > ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> > feature [-Werror,-Wtypedef-redefinition]\\\"\\n> >\\n> > I'll look in the other templates to see if what they do.\\n>\\n> Their \\\"declare\\\" sections have full typedefs. I found it works to leave\\n> out the typedef for the \\\"define\\\" section, but I first want to\\n> reproduce the build failure.\\n\\nRight. I've reproduced this build failure on my machine by specifying\\nflags \\\"-Wtypedef-redefinition -std=gnu99\\\" to clang. Something the\\nbelow change seems to fix the problem:\\n\\n--- a/src/include/lib/radixtree.h\\n+++ b/src/include/lib/radixtree.h\\n@@ -676,7 +676,7 @@ typedef struct RT_RADIX_TREE_CONTROL\\n } RT_RADIX_TREE_CONTROL;\\n\\n /* Entry point for allocating and accessing the tree */\\n-typedef struct RT_RADIX_TREE\\n+struct RT_RADIX_TREE\\n {\\n MemoryContext context;\\n\\n@@ -691,7 +691,7 @@ typedef struct RT_RADIX_TREE\\n /* leaf_context is used only for single-value leaves */\\n MemoryContextData *leaf_context;\\n #endif\\n-} RT_RADIX_TREE;\\n+};\\n\\n /*\\n * Iteration support.\\n@@ -714,7 +714,7 @@ typedef struct RT_NODE_ITER\\n } RT_NODE_ITER;\\n\\n /* state for iterating over the whole radix tree */\\n-typedef struct RT_ITER\\n+struct RT_ITER\\n {\\n RT_RADIX_TREE *tree;\\n\\n@@ -728,7 +728,7 @@ typedef struct RT_ITER\\n\\n /* The key constructed during iteration */\\n uint64 key;\\n-} RT_ITER;\\n+};\\n\\n\\n /* verification (available only in assert-enabled builds) */\\n\\n>\\n> In addition, olingo and grassquit are showing different kinds of\\n> \\\"AddressSanitizer: odr-violation\\\" errors, which I'm not sure what to\\n> make of -- example:\\n>\\n> ==1862767==ERROR: AddressSanitizer: odr-violation (0x7fc257476b60):\\n> [1] size=256 'pg_leftmost_one_pos'\\n> /home/bf/bf-build/olingo/HEAD/pgsql.build/../pgsql/src/port/pg_bitutils.c:34\\n> [2] size=256 'pg_leftmost_one_pos'\\n> /home/bf/bf-build/olingo/HEAD/pgsql.build/../pgsql/src/port/pg_bitutils.c:34\\n> These globals were registered at these points:\\n> [1]:\\n> #0 0x563564b97bf6 in __asan_register_globals\\n> (/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e2bf6)\\n> (BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n> #1 0x563564b98d1d in __asan_register_elf_globals\\n> (/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e3d1d)\\n> (BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n> #2 0x7fc265c3fe3d in call_init elf/dl-init.c:74:3\\n> #3 0x7fc265c3fe3d in call_init elf/dl-init.c:26:1\\n>\\n> [2]:\\n> #0 0x563564b97bf6 in __asan_register_globals\\n> (/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e2bf6)\\n> (BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n> #1 0x563564b98d1d in __asan_register_elf_globals\\n> (/home/bf/bf-build/olingo/HEAD/pgsql.build/tmp_install/home/bf/bf-build/olingo/HEAD/inst/bin/postgres+0x3e3d1d)\\n> (BuildId: e2ff70bf14f342e03f451bba119134a49a50b8b8)\\n> #2 0x7fc2649847f5 in call_init csu/../csu/libc-start.c:145:3\\n> #3 0x7fc2649847f5 in __libc_start_main csu/../csu/libc-start.c:347:5\\n\\nI'll look at them too.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 15:27:02 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 3:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> >\\n> > In addition, olingo and grassquit are showing different kinds of\\n> > \\\"AddressSanitizer: odr-violation\\\" errors, which I'm not sure what to\\n> > make of -- example:\\n\\nodr-violation seems to refer to One Definition Rule (ODR). According\\nto Wikipedia[1]:\\n\\nThe One Definition Rule (ODR) is an important rule of the C++\\nprogramming language that prescribes that classes/structs and\\nnon-inline functions cannot have more than one definition in the\\nentire program and template and types cannot have more than one\\ndefinition by translation unit. It is defined in the ISO C++ Standard\\n(ISO/IEC 14882) 2003, at section 3.2. Some other programming languages\\nhave similar but differently defined rules towards the same objective.\\n\\nI don't fully understand this concept yet but are these two different\\nbuild failures related?\\n\\nRegards,\\n\\n[1] https://en.wikipedia.org/wiki/One_Definition_Rule\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 15:49:18 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 1:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > > ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> > > feature [-Werror,-Wtypedef-redefinition]\\\"\\n> > >\\n> > > I'll look in the other templates to see if what they do.\\n> >\\n> > Their \\\"declare\\\" sections have full typedefs. I found it works to leave\\n> > out the typedef for the \\\"define\\\" section, but I first want to\\n> > reproduce the build failure.\\n>\\n> Right. I've reproduced this build failure on my machine by specifying\\n> flags \\\"-Wtypedef-redefinition -std=gnu99\\\" to clang. Something the\\n> below change seems to fix the problem:\\n\\nConfirmed, will push shortly.\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 14:01:02 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 4:01 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 1:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > > ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> > > > feature [-Werror,-Wtypedef-redefinition]\\\"\\n> > > >\\n> > > > I'll look in the other templates to see if what they do.\\n> > >\\n> > > Their \\\"declare\\\" sections have full typedefs. I found it works to leave\\n> > > out the typedef for the \\\"define\\\" section, but I first want to\\n> > > reproduce the build failure.\\n> >\\n> > Right. I've reproduced this build failure on my machine by specifying\\n> > flags \\\"-Wtypedef-redefinition -std=gnu99\\\" to clang. Something the\\n> > below change seems to fix the problem:\\n>\\n> Confirmed, will push shortly.\\n\\nmamba complained different build errors[1]:\\n\\n 2740 | fprintf(stderr, \\\"num_keys = %ld\\\\\\\\n\\\", tree->ctl->num_keys);\\n | ~~^ ~~~~~~~~~~~~~~~~~~~\\n | | |\\n | long int int64 {aka long long int}\\n | %lld\\n../../../../src/include/lib/radixtree.h:2752:30: error: format '%ld'\\nexpects argument of type 'long int', but argument 4 has type 'int64'\\n{aka 'long long int'} [-Werror=format=]\\n 2752 | fprintf(stderr, \\\", n%d = %ld\\\", size_class.fanout,\\ntree->ctl->num_nodes[i]);\\n | ~~^\\n~~~~~~~~~~~~~~~~~~~~~~~\\n | |\\n |\\n | long int\\n int64 {aka long long int}\\n | %lld\\n../../../../src/include/lib/radixtree.h:2755:32: error: format '%ld'\\nexpects argument of type 'long int', but argument 3 has type 'int64'\\n{aka 'long long int'} [-Werror=format=]\\n 2755 | fprintf(stderr, \\\", leaves = %ld\\\", tree->ctl->num_leaves);\\n | ~~^ ~~~~~~~~~~~~~~~~~~~~~\\n | | |\\n | long int int64 {aka long long int}\\n | %lld\\n\\nRegards,\\n\\n[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2024-03-07%2006%3A05%3A18\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 16:13:50 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 2:14 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 4:01 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 1:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > >\\n> > > > On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > > > > ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> > > > > feature [-Werror,-Wtypedef-redefinition]\\\"\\n> > > > >\\n> > > > > I'll look in the other templates to see if what they do.\\n> > > >\\n> > > > Their \\\"declare\\\" sections have full typedefs. I found it works to leave\\n> > > > out the typedef for the \\\"define\\\" section, but I first want to\\n> > > > reproduce the build failure.\\n> > >\\n> > > Right. I've reproduced this build failure on my machine by specifying\\n> > > flags \\\"-Wtypedef-redefinition -std=gnu99\\\" to clang. Something the\\n> > > below change seems to fix the problem:\\n> >\\n> > Confirmed, will push shortly.\\n>\\n> mamba complained different build errors[1]:\\n>\\n> 2740 | fprintf(stderr, \\\"num_keys = %ld\\\\\\\\n\\\", tree->ctl->num_keys);\\n> | ~~^ ~~~~~~~~~~~~~~~~~~~\\n> | | |\\n> | long int int64 {aka long long int}\\n> | %lld\\n> ../../../../src/include/lib/radixtree.h:2752:30: error: format '%ld'\\n> expects argument of type 'long int', but argument 4 has type 'int64'\\n> {aka 'long long int'} [-Werror=format=]\\n> 2752 | fprintf(stderr, \\\", n%d = %ld\\\", size_class.fanout,\\n> tree->ctl->num_nodes[i]);\\n> | ~~^\\n> ~~~~~~~~~~~~~~~~~~~~~~~\\n> | |\\n> |\\n> | long int\\n> int64 {aka long long int}\\n> | %lld\\n> ../../../../src/include/lib/radixtree.h:2755:32: error: format '%ld'\\n> expects argument of type 'long int', but argument 3 has type 'int64'\\n> {aka 'long long int'} [-Werror=format=]\\n> 2755 | fprintf(stderr, \\\", leaves = %ld\\\", tree->ctl->num_leaves);\\n> | ~~^ ~~~~~~~~~~~~~~~~~~~~~\\n> | | |\\n> | long int int64 {aka long long int}\\n> | %lld\\n>\\n> Regards,\\n>\\n> [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2024-03-07%2006%3A05%3A18\\n\\nYeah, the attached fixes it for me.\",\n \"msg_date\": \"Thu, 7 Mar 2024 14:21:03 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 4:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 2:14 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 4:01 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 7, 2024 at 1:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > >\\n> > > > On Thu, Mar 7, 2024 at 3:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > >\\n> > > > > On Thu, Mar 7, 2024 at 12:59 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > > > > ... cause \\\"error: redefinition of typedef 'rt_radix_tree' is a C11\\n> > > > > > feature [-Werror,-Wtypedef-redefinition]\\\"\\n> > > > > >\\n> > > > > > I'll look in the other templates to see if what they do.\\n> > > > >\\n> > > > > Their \\\"declare\\\" sections have full typedefs. I found it works to leave\\n> > > > > out the typedef for the \\\"define\\\" section, but I first want to\\n> > > > > reproduce the build failure.\\n> > > >\\n> > > > Right. I've reproduced this build failure on my machine by specifying\\n> > > > flags \\\"-Wtypedef-redefinition -std=gnu99\\\" to clang. Something the\\n> > > > below change seems to fix the problem:\\n> > >\\n> > > Confirmed, will push shortly.\\n> >\\n> > mamba complained different build errors[1]:\\n> >\\n> > 2740 | fprintf(stderr, \\\"num_keys = %ld\\\\\\\\n\\\", tree->ctl->num_keys);\\n> > | ~~^ ~~~~~~~~~~~~~~~~~~~\\n> > | | |\\n> > | long int int64 {aka long long int}\\n> > | %lld\\n> > ../../../../src/include/lib/radixtree.h:2752:30: error: format '%ld'\\n> > expects argument of type 'long int', but argument 4 has type 'int64'\\n> > {aka 'long long int'} [-Werror=format=]\\n> > 2752 | fprintf(stderr, \\\", n%d = %ld\\\", size_class.fanout,\\n> > tree->ctl->num_nodes[i]);\\n> > | ~~^\\n> > ~~~~~~~~~~~~~~~~~~~~~~~\\n> > | |\\n> > |\\n> > | long int\\n> > int64 {aka long long int}\\n> > | %lld\\n> > ../../../../src/include/lib/radixtree.h:2755:32: error: format '%ld'\\n> > expects argument of type 'long int', but argument 3 has type 'int64'\\n> > {aka 'long long int'} [-Werror=format=]\\n> > 2755 | fprintf(stderr, \\\", leaves = %ld\\\", tree->ctl->num_leaves);\\n> > | ~~^ ~~~~~~~~~~~~~~~~~~~~~\\n> > | | |\\n> > | long int int64 {aka long long int}\\n> > | %lld\\n> >\\n> > Regards,\\n> >\\n> > [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2024-03-07%2006%3A05%3A18\\n>\\n> Yeah, the attached fixes it for me.\\n\\nThanks, LGTM.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 16:32:21 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 1:49 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> odr-violation seems to refer to One Definition Rule (ODR). According\\n> to Wikipedia[1]:\\n>\\n> The One Definition Rule (ODR) is an important rule of the C++\\n> programming language that prescribes that classes/structs and\\n> non-inline functions cannot have more than one definition in the\\n> entire program and template and types cannot have more than one\\n> definition by translation unit. It is defined in the ISO C++ Standard\\n> (ISO/IEC 14882) 2003, at section 3.2. Some other programming languages\\n> have similar but differently defined rules towards the same objective.\\n>\\n> I don't fully understand this concept yet but are these two different\\n> build failures related?\\n\\nI thought it may have something to do with the prerequisite commit\\nthat moved some symbols from bitmapset.c to .h:\\n\\n/* Select appropriate bit-twiddling functions for bitmap word size */\\n#if BITS_PER_BITMAPWORD == 32\\n#define bmw_leftmost_one_pos(w) pg_leftmost_one_pos32(w)\\n#define bmw_rightmost_one_pos(w) pg_rightmost_one_pos32(w)\\n#define bmw_popcount(w) pg_popcount32(w)\\n#elif BITS_PER_BITMAPWORD == 64\\n#define bmw_leftmost_one_pos(w) pg_leftmost_one_pos64(w)\\n#define bmw_rightmost_one_pos(w) pg_rightmost_one_pos64(w)\\n#define bmw_popcount(w) pg_popcount64(w)\\n#else\\n#error \\\"invalid BITS_PER_BITMAPWORD\\\"\\n#endif\\n\\n...but olingo's error seems strange to me, because it is complaining\\nof pg_leftmost_one_pos, which refers to the lookup table in\\npg_bitutils.c -- I thought all buildfarm members used the bitscan\\ninstructions.\\n\\ngrassquit is complaining of pg_popcount64, which is a global function,\\nalso in pg_bitutils.c. Not sure what to make of this, since we're just\\npointing symbols at things which should have a single definition...\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 15:18:11 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 1:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> In addition, olingo and grassquit are showing different kinds of\\n> \\\"AddressSanitizer: odr-violation\\\" errors, which I'm not sure what to\\n> make of -- example:\\n\\nThis might be relevant:\\n\\n$ git grep 'link_with: pgport_srv'\\nsrc/test/modules/test_radixtree/meson.build: link_with: pgport_srv,\\n\\nNo other test module uses this directive, and indeed, removing this\\nstill builds fine for me. Thoughts?\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 16:37:10 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 6:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 1:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > In addition, olingo and grassquit are showing different kinds of\\n> > \\\"AddressSanitizer: odr-violation\\\" errors, which I'm not sure what to\\n> > make of -- example:\\n>\\n> This might be relevant:\\n>\\n> $ git grep 'link_with: pgport_srv'\\n> src/test/modules/test_radixtree/meson.build: link_with: pgport_srv,\\n>\\n> No other test module uses this directive, and indeed, removing this\\n> still builds fine for me. Thoughts?\\n\\nYeah, it could be the culprit. The test_radixtree/meson.build is the\\nsole extension that explicitly specifies a link with pgport_srv. I\\nthink we can get rid of it as I've also confirmed the build still fine\\neven without it.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 18:46:48 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 4:47 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 6:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > $ git grep 'link_with: pgport_srv'\\n> > src/test/modules/test_radixtree/meson.build: link_with: pgport_srv,\\n> >\\n> > No other test module uses this directive, and indeed, removing this\\n> > still builds fine for me. Thoughts?\\n>\\n> Yeah, it could be the culprit. The test_radixtree/meson.build is the\\n> sole extension that explicitly specifies a link with pgport_srv. I\\n> think we can get rid of it as I've also confirmed the build still fine\\n> even without it.\\n\\nolingo and grassquit have turned green, so that must have been it.\\n\\n\\n\",\n \"msg_date\": \"Thu, 7 Mar 2024 18:06:13 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 8:06 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 4:47 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 6:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > $ git grep 'link_with: pgport_srv'\\n> > > src/test/modules/test_radixtree/meson.build: link_with: pgport_srv,\\n> > >\\n> > > No other test module uses this directive, and indeed, removing this\\n> > > still builds fine for me. Thoughts?\\n> >\\n> > Yeah, it could be the culprit. The test_radixtree/meson.build is the\\n> > sole extension that explicitly specifies a link with pgport_srv. I\\n> > think we can get rid of it as I've also confirmed the build still fine\\n> > even without it.\\n>\\n> olingo and grassquit have turned green, so that must have been it.\\n\\nCool!\\n\\nI've attached the remaining patches for CI. I've made some minor\\nchanges in separate patches and drafted the commit message for\\ntidstore patch.\\n\\nWhile reviewing the tidstore code, I thought that it would be more\\nappropriate to place tidstore.c under src/backend/lib instead of\\nsrc/backend/common/access since the tidstore is no longer implemented\\nonly for heap or other access methods, and it might also be used by\\nexecutor nodes in the future. What do you think?\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Fri, 8 Mar 2024 00:34:48 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 8:06 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 4:47 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 6:37 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > $ git grep 'link_with: pgport_srv'\\n> > > src/test/modules/test_radixtree/meson.build: link_with: pgport_srv,\\n> > >\\n> > > No other test module uses this directive, and indeed, removing this\\n> > > still builds fine for me. Thoughts?\\n> >\\n> > Yeah, it could be the culprit. The test_radixtree/meson.build is the\\n> > sole extension that explicitly specifies a link with pgport_srv. I\\n> > think we can get rid of it as I've also confirmed the build still fine\\n> > even without it.\\n>\\n> olingo and grassquit have turned green, so that must have been it.\\n\\nfairywren is complaining another build failure:\\n\\n[1931/2156] \\\"gcc\\\" -o\\nsrc/test/modules/test_radixtree/test_radixtree.dll\\nsrc/test/modules/test_radixtree/test_radixtree.dll.p/win32ver.obj\\nsrc/test/modules/test_radixtree/test_radixtree.dll.p/test_radixtree.c.obj\\n\\\"-Wl,--allow-shlib-undefined\\\" \\\"-shared\\\" \\\"-Wl,--start-group\\\"\\n\\\"-Wl,--out-implib=src/test\\\\\\\\modules\\\\\\\\test_radixtree\\\\\\\\test_radixtree.dll.a\\\"\\n\\\"-Wl,--stack,4194304\\\" \\\"-Wl,--allow-multiple-definition\\\"\\n\\\"-Wl,--disable-auto-import\\\" \\\"-fvisibility=hidden\\\"\\n\\\"C:/tools/nmsys64/home/pgrunner/bf/root/HEAD/pgsql.build/src/backend/libpostgres.exe.a\\\"\\n\\\"-pthread\\\" \\\"C:/tools/nmsys64/ucrt64/bin/../lib/libssl.dll.a\\\"\\n\\\"C:/tools/nmsys64/ucrt64/bin/../lib/libcrypto.dll.a\\\"\\n\\\"C:/tools/nmsys64/ucrt64/bin/../lib/libz.dll.a\\\" \\\"-lws2_32\\\" \\\"-lm\\\"\\n\\\"-lkernel32\\\" \\\"-luser32\\\" \\\"-lgdi32\\\" \\\"-lwinspool\\\" \\\"-lshell32\\\" \\\"-lole32\\\"\\n\\\"-loleaut32\\\" \\\"-luuid\\\" \\\"-lcomdlg32\\\" \\\"-ladvapi32\\\" \\\"-Wl,--end-group\\\"\\nFAILED: src/test/modules/test_radixtree/test_radixtree.dll\\n\\\"gcc\\\" -o src/test/modules/test_radixtree/test_radixtree.dll\\nsrc/test/modules/test_radixtree/test_radixtree.dll.p/win32ver.obj\\nsrc/test/modules/test_radixtree/test_radixtree.dll.p/test_radixtree.c.obj\\n\\\"-Wl,--allow-shlib-undefined\\\" \\\"-shared\\\" \\\"-Wl,--start-group\\\"\\n\\\"-Wl,--out-implib=src/test\\\\\\\\modules\\\\\\\\test_radixtree\\\\\\\\test_radixtree.dll.a\\\"\\n\\\"-Wl,--stack,4194304\\\" \\\"-Wl,--allow-multiple-definition\\\"\\n\\\"-Wl,--disable-auto-import\\\" \\\"-fvisibility=hidden\\\"\\n\\\"C:/tools/nmsys64/home/pgrunner/bf/root/HEAD/pgsql.build/src/backend/libpostgres.exe.a\\\"\\n\\\"-pthread\\\" \\\"C:/tools/nmsys64/ucrt64/bin/../lib/libssl.dll.a\\\"\\n\\\"C:/tools/nmsys64/ucrt64/bin/../lib/libcrypto.dll.a\\\"\\n\\\"C:/tools/nmsys64/ucrt64/bin/../lib/libz.dll.a\\\" \\\"-lws2_32\\\" \\\"-lm\\\"\\n\\\"-lkernel32\\\" \\\"-luser32\\\" \\\"-lgdi32\\\" \\\"-lwinspool\\\" \\\"-lshell32\\\" \\\"-lole32\\\"\\n\\\"-loleaut32\\\" \\\"-luuid\\\" \\\"-lcomdlg32\\\" \\\"-ladvapi32\\\" \\\"-Wl,--end-group\\\"\\nC:/tools/nmsys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe:\\nsrc/test/modules/test_radixtree/test_radixtree.dll.p/test_radixtree.c.obj:test_radixtree:(.rdata$.refptr.pg_popcount64[.refptr.pg_popcount64]+0x0):\\nundefined reference to `pg_popcount64'\\n\\nIt looks like it requires a link with pgport_srv but I'm not sure. It\\nseems that the recent commit 1f1d73a8b breaks CI, Windows - Server\\n2019, VS 2019 - Meson & ninja, too.\\n\\nRegards,\\n\\n[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=fairywren&dt=2024-03-07%2012%3A53%3A20\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 01:14:41 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 11:15 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> It looks like it requires a link with pgport_srv but I'm not sure. It\\n> seems that the recent commit 1f1d73a8b breaks CI, Windows - Server\\n> 2019, VS 2019 - Meson & ninja, too.\\n\\nUnfortunately, none of the Windows animals happened to run both after\\nthe initial commit and before removing the (seemingly useless on our\\ndaily platfoms) link. I'll confirm on my own CI branch in a few\\nminutes.\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 08:04:39 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 8, 2024 at 10:04 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 11:15 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > It looks like it requires a link with pgport_srv but I'm not sure. It\\n> > seems that the recent commit 1f1d73a8b breaks CI, Windows - Server\\n> > 2019, VS 2019 - Meson & ninja, too.\\n>\\n> Unfortunately, none of the Windows animals happened to run both after\\n> the initial commit and before removing the (seemingly useless on our\\n> daily platfoms) link. I'll confirm on my own CI branch in a few\\n> minutes.\\n\\nYesterday I've confirmed the something like the below fixes the\\nproblem happened in Windows CI:\\n\\n--- a/src/test/modules/test_radixtree/meson.build\\n+++ b/src/test/modules/test_radixtree/meson.build\\n@@ -12,6 +12,7 @@ endif\\n\\n test_radixtree = shared_module('test_radixtree',\\n test_radixtree_sources,\\n+ link_with: host_system == 'windows' ? pgport_srv : [],\\n kwargs: pg_test_mod_args,\\n )\\n test_install_libs += test_radixtree\\n\\nBut I'm not sure it's the right fix especially because I guess it\\ncould raise \\\"AddressSanitizer: odr-violation\\\" error on Windows.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 10:08:40 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 8, 2024 at 8:09 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> Yesterday I've confirmed the something like the below fixes the\\n> problem happened in Windows CI:\\n\\nGlad you shared before I went and did it.\\n\\n> --- a/src/test/modules/test_radixtree/meson.build\\n> +++ b/src/test/modules/test_radixtree/meson.build\\n> @@ -12,6 +12,7 @@ endif\\n>\\n> test_radixtree = shared_module('test_radixtree',\\n> test_radixtree_sources,\\n> + link_with: host_system == 'windows' ? pgport_srv : [],\\n\\nI don't see any similar coding elsewhere, so that leaves me wondering\\nif we're missing something. On the other hand, maybe no test modules\\nuse files in src/port ...\\n\\n> kwargs: pg_test_mod_args,\\n> )\\n> test_install_libs += test_radixtree\\n>\\n> But I'm not sure it's the right fix especially because I guess it\\n> could raise \\\"AddressSanitizer: odr-violation\\\" error on Windows.\\n\\nWell, it's now at zero definitions that it can see, so I imagine it's\\npossible that adding the above would not cause more than one. In any\\ncase, we might not know since as far as I can tell the MSVC animals\\ndon't have address sanitizer. I'll look around some more, and if I\\ndon't get any revelations, I guess we should go with the above.\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 08:31:37 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 8, 2024 at 8:09 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> Yesterday I've confirmed the something like the below fixes the\\n> problem happened in Windows CI:\\n>\\n> --- a/src/test/modules/test_radixtree/meson.build\\n> +++ b/src/test/modules/test_radixtree/meson.build\\n> @@ -12,6 +12,7 @@ endif\\n>\\n> test_radixtree = shared_module('test_radixtree',\\n> test_radixtree_sources,\\n> + link_with: host_system == 'windows' ? pgport_srv : [],\\n> kwargs: pg_test_mod_args,\\n> )\\n> test_install_libs += test_radixtree\\n\\npgport_srv is for backend, shared libraries should be using pgport_shlib\\n\\nFurther, the top level meson.build has:\\n\\n# all shared libraries not part of the backend should depend on this\\nfrontend_shlib_code = declare_dependency(\\n include_directories: [postgres_inc],\\n link_with: [common_shlib, pgport_shlib],\\n sources: generated_headers,\\n dependencies: [shlib_code, os_deps, libintl],\\n)\\n\\n...but the only things that declare needing frontend_shlib_code are in\\nsrc/interfaces/.\\n\\nIn any case, I'm trying it in CI branch with pgport_shlib now.\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 09:53:43 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 8, 2024 at 9:53 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Mar 8, 2024 at 8:09 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > Yesterday I've confirmed the something like the below fixes the\\n> > problem happened in Windows CI:\\n> >\\n> > --- a/src/test/modules/test_radixtree/meson.build\\n> > +++ b/src/test/modules/test_radixtree/meson.build\\n> > @@ -12,6 +12,7 @@ endif\\n> >\\n> > test_radixtree = shared_module('test_radixtree',\\n> > test_radixtree_sources,\\n> > + link_with: host_system == 'windows' ? pgport_srv : [],\\n> > kwargs: pg_test_mod_args,\\n> > )\\n> > test_install_libs += test_radixtree\\n>\\n> pgport_srv is for backend, shared libraries should be using pgport_shlib\\n\\n> In any case, I'm trying it in CI branch with pgport_shlib now.\\n\\nThat seems to work, so I'll push that just to get things green again.\\n\\n\\n\",\n \"msg_date\": \"Fri, 8 Mar 2024 10:22:41 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 7, 2024 at 10:35 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I've attached the remaining patches for CI. I've made some minor\\n> changes in separate patches and drafted the commit message for\\n> tidstore patch.\\n>\\n> While reviewing the tidstore code, I thought that it would be more\\n> appropriate to place tidstore.c under src/backend/lib instead of\\n> src/backend/common/access since the tidstore is no longer implemented\\n> only for heap or other access methods, and it might also be used by\\n> executor nodes in the future. What do you think?\\n\\nThat's a heck of a good question. I don't think src/backend/lib is\\nright -- it seems that's for general-purpose data structures.\\nSomething like backend/utils is also too general.\\nsrc/backend/access/common has things for tuple descriptors, toast,\\nsessions, and I don't think tidstore is out of place here. I'm not\\nsure there's a better place, but I could be convinced otherwise.\\n\\nv68-0001:\\n\\nI'm not sure if commit messages are much a subject of review, and it's\\nup to the committer, but I'll share a couple comments just as\\nsomething to think about, not something I would ask you to change: I\\nthink it's a bit distracting that the commit message talks about the\\njustification to use it for vacuum. Let's save that for the commit\\nwith actual vacuum changes. Also, I suspect saying there are a \\\"wide\\nrange\\\" of uses is over-selling it a bit, and that paragraph is a bit\\nawkward aside from that.\\n\\n+ /* Collect TIDs extracted from the key-value pair */\\n+ result->num_offsets = 0;\\n+\\n\\nThis comment has nothing at all to do with this line. If the comment\\nis for several lines following, some of which are separated by blank\\nlines, there should be a blank line after the comment. Also, why isn't\\ntidstore_iter_extract_tids() responsible for setting that to zero?\\n\\n+ ts->context = CurrentMemoryContext;\\n\\nAs far as I can tell, this member is never accessed again -- am I\\nmissing something?\\n\\n+ /* DSA for tidstore will be detached at the end of session */\\n\\nNo other test module pins the mapping, but that doesn't necessarily\\nmean it's wrong. Is there some advantage over explicitly detaching?\\n\\n+-- Add tids in random order.\\n\\nI don't see any randomization here. I do remember adding row_number to\\nremove whitespace in the output, but I don't remember a random order.\\nOn that subject, the row_number was an easy trick to avoid extra\\nwhitespace, but maybe we should just teach the setting function to\\nreturn blocknumber rather than null?\\n\\n+Datum\\n+tidstore_create(PG_FUNCTION_ARGS)\\n+{\\n...\\n+ tidstore = TidStoreCreate(max_bytes, dsa);\\n\\n+Datum\\n+tidstore_set_block_offsets(PG_FUNCTION_ARGS)\\n+{\\n....\\n+ TidStoreSetBlockOffsets(tidstore, blkno, offs, noffs);\\n\\nThese names are too similar. Maybe the test module should do\\ns/tidstore_/test_/ or similar.\\n\\n+/* Sanity check if we've called tidstore_create() */\\n+static void\\n+check_tidstore_available(void)\\n+{\\n+ if (tidstore == NULL)\\n+ elog(ERROR, \\\"tidstore is not initialized\\\");\\n+}\\n\\nI don't find this very helpful. If a developer wiped out the create\\ncall, wouldn't the test crash and burn pretty obviously?\\n\\nIn general, the .sql file is still very hard-coded. Functions are\\ncreated that contain a VALUES statement. Maybe it's okay for now, but\\nwanted to mention it. Ideally, we'd have some randomized tests,\\nwithout having to display it. That could be in addition to (not\\nreplacing) the small tests we have that display input. (see below)\\n\\n\\nv68-0002:\\n\\n@@ -329,6 +381,13 @@ TidStoreIsMember(TidStore *ts, ItemPointer tid)\\n\\n ret = (page->words[wordnum] & ((bitmapword) 1 << bitnum)) != 0;\\n\\n+#ifdef TIDSTORE_DEBUG\\n+ if (!TidStoreIsShared(ts))\\n+ {\\n+ bool ret_debug = ts_debug_is_member(ts, tid);;\\n+ Assert(ret == ret_debug);\\n+ }\\n+#endif\\n\\nThis only checking the case where we haven't returned already. In particular...\\n\\n+ /* no entry for the blk */\\n+ if (page == NULL)\\n+ return false;\\n+\\n+ wordnum = WORDNUM(off);\\n+ bitnum = BITNUM(off);\\n+\\n+ /* no bitmap for the off */\\n+ if (wordnum >= page->nwords)\\n+ return false;\\n\\n...these results are not checked.\\n\\nMore broadly, it seems like the test module should be able to test\\neverything that the debug-build array would complain about. Including\\nordered iteration. This may require first saving our test input to a\\ntable. We could create a cursor on a query that fetches the ordered\\ninput from the table and verifies that the tid store iterate produces\\nthe same ordered set, maybe with pl/pgSQL. Or something like that.\\nSeems like not a whole lot of work. I can try later in the week, if\\nyou like.\\n\\nv68-0005/6 look ready to squash\\n\\nv68-0008 - I'm not a fan of captilizing short comment fragments. I use\\nthe style of either: short lower-case phrases, or full sentences\\nincluding capitalization, correct grammar and period. I see these two\\nstyles all over the code base, as appropriate.\\n\\n+ /* Remain attached until end of backend */\\n\\nWe'll probably want this comment, if in fact we want this behavior.\\n\\n+ /*\\n+ * Note that funcctx->call_cntr is incremented in SRF_RETURN_NEXT\\n+ * before return.\\n+ */\\n\\nI'm not sure what this is trying to say or why it's relevant, since\\nit's been a while since I've written a SRF in C.\\n\\nThat's all I have for now, and I haven't looked at the vacuum changes this time.\\n\\n\\n\",\n \"msg_date\": \"Mon, 11 Mar 2024 10:19:52 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Feb 16, 2024 at 10:05 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Feb 15, 2024 at 8:26 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > v61-0007: Runtime-embeddable tids -- Optional for v17, but should\\n> > reduce memory regressions, so should be considered. Up to 3 tids can\\n> > be stored in the last level child pointer. It's not polished, but I'll\\n> > only proceed with that if we think we need this. \\\"flags\\\" iis called\\n> > that because it could hold tidbitmap.c booleans (recheck, lossy) in\\n> > the future, in addition to reserving space for the pointer tag. Note:\\n> > I hacked the tests to only have 2 offsets per block to demo, but of\\n> > course both paths should be tested.\\n>\\n> Interesting. I've run the same benchmark tests we did[1][2] (the\\n> median of 3 runs):\\n[found a big speed-up where we don't expect one]\\n\\nI tried to reproduce this (similar patch, but rebased on top of a bug\\nyou recently fixed (possibly related?) -- attached, and also shows one\\nway to address some lack of coverage in the debug build, for as long\\nas we test that with CI).\\n\\nFortunately I cannot see a difference, so I believe it's not affecting\\nthe case in this test all, as expected:\\n\\nv68:\\n\\nINFO: finished vacuuming \\\"john.public.test\\\": index scans: 1\\npages: 0 removed, 442478 remain, 88478 scanned (20.00% of total)\\ntuples: 19995999 removed, 80003979 remain, 0 are dead but not yet removable\\nremovable cutoff: 770, which was 0 XIDs old when operation ended\\nfrozen: 0 pages from table (0.00% of total) had 0 tuples frozen\\nindex scan needed: 88478 pages from table (20.00% of total) had\\n19995999 dead item identifiers removed\\nindex \\\"test_x_idx\\\": pages: 274194 in total, 54822 newly deleted, 54822\\ncurrently deleted, 0 reusable\\navg read rate: 620.356 MB/s, avg write rate: 124.105 MB/s\\nbuffer usage: 758236 hits, 274196 misses, 54854 dirtied\\nWAL usage: 2 records, 0 full page images, 425 bytes\\n\\nsystem usage: CPU: user: 3.74 s, system: 0.68 s, elapsed: 4.45 s\\nsystem usage: CPU: user: 3.02 s, system: 0.42 s, elapsed: 3.47 s\\nsystem usage: CPU: user: 3.09 s, system: 0.38 s, elapsed: 3.49 s\\nsystem usage: CPU: user: 3.00 s, system: 0.43 s, elapsed: 3.45 s\\n\\nv68 + emb values (that cannot be used because > 3 tids per block):\\n\\nINFO: finished vacuuming \\\"john.public.test\\\": index scans: 1\\npages: 0 removed, 442478 remain, 88478 scanned (20.00% of total)\\ntuples: 19995999 removed, 80003979 remain, 0 are dead but not yet removable\\nremovable cutoff: 775, which was 0 XIDs old when operation ended\\nfrozen: 0 pages from table (0.00% of total) had 0 tuples frozen\\nindex scan needed: 88478 pages from table (20.00% of total) had\\n19995999 dead item identifiers removed\\nindex \\\"test_x_idx\\\": pages: 274194 in total, 54822 newly deleted, 54822\\ncurrently deleted, 0 reusable\\navg read rate: 570.808 MB/s, avg write rate: 114.192 MB/s\\nbuffer usage: 758236 hits, 274196 misses, 54854 dirtied\\nWAL usage: 2 records, 0 full page images, 425 bytes\\n\\nsystem usage: CPU: user: 3.11 s, system: 0.62 s, elapsed: 3.75 s\\nsystem usage: CPU: user: 3.04 s, system: 0.41 s, elapsed: 3.46 s\\nsystem usage: CPU: user: 3.05 s, system: 0.41 s, elapsed: 3.47 s\\nsystem usage: CPU: user: 3.04 s, system: 0.43 s, elapsed: 3.49 s\\n\\nI'll continue polishing the runtime-embeddable values patch as time\\npermits, for later consideration.\",\n \"msg_date\": \"Mon, 11 Mar 2024 14:32:20 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 11, 2024 at 12:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 7, 2024 at 10:35 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I've attached the remaining patches for CI. I've made some minor\\n> > changes in separate patches and drafted the commit message for\\n> > tidstore patch.\\n> >\\n> > While reviewing the tidstore code, I thought that it would be more\\n> > appropriate to place tidstore.c under src/backend/lib instead of\\n> > src/backend/common/access since the tidstore is no longer implemented\\n> > only for heap or other access methods, and it might also be used by\\n> > executor nodes in the future. What do you think?\\n>\\n> That's a heck of a good question. I don't think src/backend/lib is\\n> right -- it seems that's for general-purpose data structures.\\n> Something like backend/utils is also too general.\\n> src/backend/access/common has things for tuple descriptors, toast,\\n> sessions, and I don't think tidstore is out of place here. I'm not\\n> sure there's a better place, but I could be convinced otherwise.\\n\\nYeah, I agreed that src/backend/lib seems not to be the place for\\ntidstore. Let's keep it in src/backend/access/common. If others think\\ndifferently, we can move it later.\\n\\n>\\n> v68-0001:\\n>\\n> I'm not sure if commit messages are much a subject of review, and it's\\n> up to the committer, but I'll share a couple comments just as\\n> something to think about, not something I would ask you to change: I\\n> think it's a bit distracting that the commit message talks about the\\n> justification to use it for vacuum. Let's save that for the commit\\n> with actual vacuum changes. Also, I suspect saying there are a \\\"wide\\n> range\\\" of uses is over-selling it a bit, and that paragraph is a bit\\n> awkward aside from that.\\n\\nThank you for the comment, and I agreed. I've updated the commit message.\\n\\n>\\n> + /* Collect TIDs extracted from the key-value pair */\\n> + result->num_offsets = 0;\\n> +\\n>\\n> This comment has nothing at all to do with this line. If the comment\\n> is for several lines following, some of which are separated by blank\\n> lines, there should be a blank line after the comment. Also, why isn't\\n> tidstore_iter_extract_tids() responsible for setting that to zero?\\n\\nAgreed, fixed.\\n\\nI also updated this part so we set result->blkno in\\ntidstore_iter_extract_tids() too, which seems more readable.\\n\\n>\\n> + ts->context = CurrentMemoryContext;\\n>\\n> As far as I can tell, this member is never accessed again -- am I\\n> missing something?\\n\\nYou're right. It was used to re-create the tidstore in the same\\ncontext again while resetting it, but we no longer support the reset\\nAPI. Considering it again, would it be better to allocate the iterator\\nstruct in the same context as we store the tidstore struct?\\n\\n>\\n> + /* DSA for tidstore will be detached at the end of session */\\n>\\n> No other test module pins the mapping, but that doesn't necessarily\\n> mean it's wrong. Is there some advantage over explicitly detaching?\\n\\nOne small benefit of not explicitly detaching dsa_area in\\ntidstore_destroy() would be simplicity; IIUC if we want to do that, we\\nneed to remember the dsa_area using (for example) a static variable,\\nand free it if it's non-NULL. I've implemented this idea in the\\nattached patch.\\n\\n>\\n> +-- Add tids in random order.\\n>\\n> I don't see any randomization here. I do remember adding row_number to\\n> remove whitespace in the output, but I don't remember a random order.\\n> On that subject, the row_number was an easy trick to avoid extra\\n> whitespace, but maybe we should just teach the setting function to\\n> return blocknumber rather than null?\\n\\nGood idea, fixed.\\n\\n>\\n> +Datum\\n> +tidstore_create(PG_FUNCTION_ARGS)\\n> +{\\n> ...\\n> + tidstore = TidStoreCreate(max_bytes, dsa);\\n>\\n> +Datum\\n> +tidstore_set_block_offsets(PG_FUNCTION_ARGS)\\n> +{\\n> ....\\n> + TidStoreSetBlockOffsets(tidstore, blkno, offs, noffs);\\n>\\n> These names are too similar. Maybe the test module should do\\n> s/tidstore_/test_/ or similar.\\n\\nAgreed.\\n\\n>\\n> +/* Sanity check if we've called tidstore_create() */\\n> +static void\\n> +check_tidstore_available(void)\\n> +{\\n> + if (tidstore == NULL)\\n> + elog(ERROR, \\\"tidstore is not initialized\\\");\\n> +}\\n>\\n> I don't find this very helpful. If a developer wiped out the create\\n> call, wouldn't the test crash and burn pretty obviously?\\n\\nRemoved.\\n\\n>\\n> In general, the .sql file is still very hard-coded. Functions are\\n> created that contain a VALUES statement. Maybe it's okay for now, but\\n> wanted to mention it. Ideally, we'd have some randomized tests,\\n> without having to display it. That could be in addition to (not\\n> replacing) the small tests we have that display input. (see below)\\n>\\n\\nAgreed to add randomized tests in addition to the existing tests.\\n\\n>\\n> v68-0002:\\n>\\n> @@ -329,6 +381,13 @@ TidStoreIsMember(TidStore *ts, ItemPointer tid)\\n>\\n> ret = (page->words[wordnum] & ((bitmapword) 1 << bitnum)) != 0;\\n>\\n> +#ifdef TIDSTORE_DEBUG\\n> + if (!TidStoreIsShared(ts))\\n> + {\\n> + bool ret_debug = ts_debug_is_member(ts, tid);;\\n> + Assert(ret == ret_debug);\\n> + }\\n> +#endif\\n>\\n> This only checking the case where we haven't returned already. In particular...\\n>\\n> + /* no entry for the blk */\\n> + if (page == NULL)\\n> + return false;\\n> +\\n> + wordnum = WORDNUM(off);\\n> + bitnum = BITNUM(off);\\n> +\\n> + /* no bitmap for the off */\\n> + if (wordnum >= page->nwords)\\n> + return false;\\n>\\n> ...these results are not checked.\\n>\\n> More broadly, it seems like the test module should be able to test\\n> everything that the debug-build array would complain about. Including\\n> ordered iteration. This may require first saving our test input to a\\n> table. We could create a cursor on a query that fetches the ordered\\n> input from the table and verifies that the tid store iterate produces\\n> the same ordered set, maybe with pl/pgSQL. Or something like that.\\n> Seems like not a whole lot of work. I can try later in the week, if\\n> you like.\\n\\nSounds a good idea. In fact, if there are some bugs in tidstore, it's\\nlikely that even initdb would fail in practice. However, it's a very\\ngood idea that we can test the tidstore anyway with such a check\\nwithout a debug-build array.\\n\\nOr as another idea, I wonder if we could keep the debug-build array in\\nsome form. For example, we use the array with the particular build\\nflag and set a BF animal for that. That way, we can test the tidstore\\nin more real cases.\\n\\n>\\n> v68-0005/6 look ready to squash\\n\\nDone.\\n\\n>\\n> v68-0008 - I'm not a fan of captilizing short comment fragments. I use\\n> the style of either: short lower-case phrases, or full sentences\\n> including capitalization, correct grammar and period. I see these two\\n> styles all over the code base, as appropriate.\\n\\nAgreed.\\n\\n>\\n> + /* Remain attached until end of backend */\\n>\\n> We'll probably want this comment, if in fact we want this behavior.\\n\\nKept it.\\n\\n>\\n> + /*\\n> + * Note that funcctx->call_cntr is incremented in SRF_RETURN_NEXT\\n> + * before return.\\n> + */\\n>\\n> I'm not sure what this is trying to say or why it's relevant, since\\n> it's been a while since I've written a SRF in C.\\n\\nI wanted to say is that we cannot do like:\\n\\nSRF_RETURN_NEXT(funcctx, PointerGetDatum(&(tids[funcctx->call_cntr])));\\n\\nbecause funcctx->call_cntr is incremented *before* return and\\ntherefore we will end up accessing the index out of range. I've took\\nsome time to realize this fact before.\\n\\n> That's all I have for now, and I haven't looked at the vacuum changes this time.\\n\\nThank you for the comments!\\n\\nIn the latest (v69) patch:\\n\\n- squashed v68-0005 and v68-0006 patches.\\n- removed most of the changes in v68-0007 patch.\\n- addressed above review comments in v69-0002 patch.\\n- v69-0003, 0004, and 0005 are miscellaneous updates.\\n\\nAs for renaming TidStore to TIDStore, I dropped the patch for now\\nsince it seems we're using \\\"Tid\\\" in some function names and variable\\nnames. If we want to update it, we can do that later.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 11 Mar 2024 17:13:17 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 11, 2024 at 5:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> In the latest (v69) patch:\\n>\\n> - squashed v68-0005 and v68-0006 patches.\\n> - removed most of the changes in v68-0007 patch.\\n> - addressed above review comments in v69-0002 patch.\\n> - v69-0003, 0004, and 0005 are miscellaneous updates.\\n\\nSince the v69 conflicts with the current HEAD, I've rebased them. In\\naddition, v70-0008 is the new patch, which cleans up the vacuum\\nintegration patch.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 12 Mar 2024 11:20:18 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 11, 2024 at 3:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Mar 11, 2024 at 12:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 7, 2024 at 10:35 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> > + ts->context = CurrentMemoryContext;\\n> >\\n> > As far as I can tell, this member is never accessed again -- am I\\n> > missing something?\\n>\\n> You're right. It was used to re-create the tidstore in the same\\n> context again while resetting it, but we no longer support the reset\\n> API. Considering it again, would it be better to allocate the iterator\\n> struct in the same context as we store the tidstore struct?\\n\\nThat makes sense.\\n\\n> > + /* DSA for tidstore will be detached at the end of session */\\n> >\\n> > No other test module pins the mapping, but that doesn't necessarily\\n> > mean it's wrong. Is there some advantage over explicitly detaching?\\n>\\n> One small benefit of not explicitly detaching dsa_area in\\n> tidstore_destroy() would be simplicity; IIUC if we want to do that, we\\n> need to remember the dsa_area using (for example) a static variable,\\n> and free it if it's non-NULL. I've implemented this idea in the\\n> attached patch.\\n\\nOkay, I don't have a strong preference at this point.\\n\\n> > +-- Add tids in random order.\\n> >\\n> > I don't see any randomization here. I do remember adding row_number to\\n> > remove whitespace in the output, but I don't remember a random order.\\n> > On that subject, the row_number was an easy trick to avoid extra\\n> > whitespace, but maybe we should just teach the setting function to\\n> > return blocknumber rather than null?\\n>\\n> Good idea, fixed.\\n\\n+ test_set_block_offsets\\n+------------------------\\n+ 2147483647\\n+ 0\\n+ 4294967294\\n+ 1\\n+ 4294967295\\n\\nHmm, was the earlier comment about randomness referring to this? I'm\\nnot sure what other regression tests do in these cases, or how\\nrelibale this is. If this is a problem we could simply insert this\\nresult into a temp table so it's not output.\\n\\n> > +Datum\\n> > +tidstore_create(PG_FUNCTION_ARGS)\\n> > +{\\n> > ...\\n> > + tidstore = TidStoreCreate(max_bytes, dsa);\\n> >\\n> > +Datum\\n> > +tidstore_set_block_offsets(PG_FUNCTION_ARGS)\\n> > +{\\n> > ....\\n> > + TidStoreSetBlockOffsets(tidstore, blkno, offs, noffs);\\n> >\\n> > These names are too similar. Maybe the test module should do\\n> > s/tidstore_/test_/ or similar.\\n>\\n> Agreed.\\n\\nMostly okay, although a couple look a bit generic now. I'll leave it\\nup to you if you want to tweak things.\\n\\n> > In general, the .sql file is still very hard-coded. Functions are\\n> > created that contain a VALUES statement. Maybe it's okay for now, but\\n> > wanted to mention it. Ideally, we'd have some randomized tests,\\n> > without having to display it. That could be in addition to (not\\n> > replacing) the small tests we have that display input. (see below)\\n> >\\n>\\n> Agreed to add randomized tests in addition to the existing tests.\\n\\nI'll try something tomorrow.\\n\\n> Sounds a good idea. In fact, if there are some bugs in tidstore, it's\\n> likely that even initdb would fail in practice. However, it's a very\\n> good idea that we can test the tidstore anyway with such a check\\n> without a debug-build array.\\n>\\n> Or as another idea, I wonder if we could keep the debug-build array in\\n> some form. For example, we use the array with the particular build\\n> flag and set a BF animal for that. That way, we can test the tidstore\\n> in more real cases.\\n\\nI think the purpose of a debug flag is to help developers catch\\nmistakes. I don't think it's quite useful enough for that. For one, it\\nhas the same 1GB limitation as vacuum's current array. For another,\\nit'd be a terrible way to debug moving tidbitmap.c from its hash table\\nto use TID store -- AND/OR operations and lossy pages are pretty much\\nundoable with a copy of vacuum's array. Last year, when I insisted on\\ntrying a long term realistic load that compares the result with the\\narray, the encoding scheme was much harder to understand in code. I\\nthink it's now easier, and there are better tests.\\n\\n> In the latest (v69) patch:\\n>\\n> - squashed v68-0005 and v68-0006 patches.\\n> - removed most of the changes in v68-0007 patch.\\n> - addressed above review comments in v69-0002 patch.\\n> - v69-0003, 0004, and 0005 are miscellaneous updates.\\n>\\n> As for renaming TidStore to TIDStore, I dropped the patch for now\\n> since it seems we're using \\\"Tid\\\" in some function names and variable\\n> names. If we want to update it, we can do that later.\\n\\nI think we're not consistent across the codebase, and it's fine to\\ndrop that patch.\\n\\nv70-0008:\\n\\n@@ -489,7 +489,7 @@ parallel_vacuum_reset_dead_items(ParallelVacuumState *pvs)\\n /*\\n * Free the current tidstore and return allocated DSA segments to the\\n * operating system. Then we recreate the tidstore with the same max_bytes\\n- * limitation.\\n+ * limitation we just used.\\n\\nNowadays, max_bytes is now more like a hint for tidstore, and not a\\nlimitation, right? Vacuum has the limitation. Maybe instead of \\\"with\\\",\\nwe should say \\\"passing the same limitation\\\".\\n\\nI wonder how \\\"di_info\\\" would look as \\\"dead_items_info\\\". I don't feel\\ntoo strongly about it, though.\\n\\nI'm going to try additional regression tests, as mentioned, and try a\\ncouple benchmarks. It should be only a couple more days.\\n\\nOne thing that occurred to me: The radix tree regression tests only\\ncompile and run the local memory case. The tidstore commit would be\\nthe first time the buildfarm has seen the shared memory case, so we\\nshould look out for possible build failures of the same sort we saw\\nwith the the radix tree tests. I see you've already removed the\\nproblematic link_with command -- that's the kind of thing to\\ndouble-check for.\\n\\n\\n\",\n \"msg_date\": \"Tue, 12 Mar 2024 17:34:30 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 12, 2024 at 7:34 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Mar 11, 2024 at 3:13 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 11, 2024 at 12:20 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 7, 2024 at 10:35 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > + ts->context = CurrentMemoryContext;\\n> > >\\n> > > As far as I can tell, this member is never accessed again -- am I\\n> > > missing something?\\n> >\\n> > You're right. It was used to re-create the tidstore in the same\\n> > context again while resetting it, but we no longer support the reset\\n> > API. Considering it again, would it be better to allocate the iterator\\n> > struct in the same context as we store the tidstore struct?\\n>\\n> That makes sense.\\n>\\n> > > + /* DSA for tidstore will be detached at the end of session */\\n> > >\\n> > > No other test module pins the mapping, but that doesn't necessarily\\n> > > mean it's wrong. Is there some advantage over explicitly detaching?\\n> >\\n> > One small benefit of not explicitly detaching dsa_area in\\n> > tidstore_destroy() would be simplicity; IIUC if we want to do that, we\\n> > need to remember the dsa_area using (for example) a static variable,\\n> > and free it if it's non-NULL. I've implemented this idea in the\\n> > attached patch.\\n>\\n> Okay, I don't have a strong preference at this point.\\n\\nI'd keep the update on that.\\n\\n>\\n> > > +-- Add tids in random order.\\n> > >\\n> > > I don't see any randomization here. I do remember adding row_number to\\n> > > remove whitespace in the output, but I don't remember a random order.\\n> > > On that subject, the row_number was an easy trick to avoid extra\\n> > > whitespace, but maybe we should just teach the setting function to\\n> > > return blocknumber rather than null?\\n> >\\n> > Good idea, fixed.\\n>\\n> + test_set_block_offsets\\n> +------------------------\\n> + 2147483647\\n> + 0\\n> + 4294967294\\n> + 1\\n> + 4294967295\\n>\\n> Hmm, was the earlier comment about randomness referring to this? I'm\\n> not sure what other regression tests do in these cases, or how\\n> relibale this is. If this is a problem we could simply insert this\\n> result into a temp table so it's not output.\\n\\nI didn't address the comment about randomness.\\n\\nI think that we will have both random TIDs tests and fixed TIDs tests\\nin test_tidstore as we discussed, and probably we can do both tests\\nwith similar steps; insert TIDs into both a temp table and tidstore\\nand check if the tidstore returned the results as expected by\\ncomparing the results to the temp table. Probably we can have a common\\npl/pgsql function that checks that and raises a WARNING or an ERROR.\\nGiven that this is very similar to what we did in test_radixtree, why\\ndo we really want to implement it using a pl/pgsql function? When we\\ndiscussed it before, I found the current way makes sense. But given\\nthat we're adding more tests and will add more tests in the future,\\ndoing the tests in C will be more maintainable and faster. Also, I\\nthink we can do the debug-build array stuff in the test_tidstore code\\ninstead.\\n\\n>\\n> > > +Datum\\n> > > +tidstore_create(PG_FUNCTION_ARGS)\\n> > > +{\\n> > > ...\\n> > > + tidstore = TidStoreCreate(max_bytes, dsa);\\n> > >\\n> > > +Datum\\n> > > +tidstore_set_block_offsets(PG_FUNCTION_ARGS)\\n> > > +{\\n> > > ....\\n> > > + TidStoreSetBlockOffsets(tidstore, blkno, offs, noffs);\\n> > >\\n> > > These names are too similar. Maybe the test module should do\\n> > > s/tidstore_/test_/ or similar.\\n> >\\n> > Agreed.\\n>\\n> Mostly okay, although a couple look a bit generic now. I'll leave it\\n> up to you if you want to tweak things.\\n>\\n> > > In general, the .sql file is still very hard-coded. Functions are\\n> > > created that contain a VALUES statement. Maybe it's okay for now, but\\n> > > wanted to mention it. Ideally, we'd have some randomized tests,\\n> > > without having to display it. That could be in addition to (not\\n> > > replacing) the small tests we have that display input. (see below)\\n> > >\\n> >\\n> > Agreed to add randomized tests in addition to the existing tests.\\n>\\n> I'll try something tomorrow.\\n>\\n> > Sounds a good idea. In fact, if there are some bugs in tidstore, it's\\n> > likely that even initdb would fail in practice. However, it's a very\\n> > good idea that we can test the tidstore anyway with such a check\\n> > without a debug-build array.\\n> >\\n> > Or as another idea, I wonder if we could keep the debug-build array in\\n> > some form. For example, we use the array with the particular build\\n> > flag and set a BF animal for that. That way, we can test the tidstore\\n> > in more real cases.\\n>\\n> I think the purpose of a debug flag is to help developers catch\\n> mistakes. I don't think it's quite useful enough for that. For one, it\\n> has the same 1GB limitation as vacuum's current array. For another,\\n> it'd be a terrible way to debug moving tidbitmap.c from its hash table\\n> to use TID store -- AND/OR operations and lossy pages are pretty much\\n> undoable with a copy of vacuum's array.\\n\\nValid points.\\n\\nAs I mentioned above, if we implement the test cases in C, we can use\\nthe debug-build array in the test code. And we won't use it in AND/OR\\noperations tests in the future.\\n\\n>\\n> > In the latest (v69) patch:\\n> >\\n> > - squashed v68-0005 and v68-0006 patches.\\n> > - removed most of the changes in v68-0007 patch.\\n> > - addressed above review comments in v69-0002 patch.\\n> > - v69-0003, 0004, and 0005 are miscellaneous updates.\\n> >\\n> > As for renaming TidStore to TIDStore, I dropped the patch for now\\n> > since it seems we're using \\\"Tid\\\" in some function names and variable\\n> > names. If we want to update it, we can do that later.\\n>\\n> I think we're not consistent across the codebase, and it's fine to\\n> drop that patch.\\n>\\n> v70-0008:\\n>\\n> @@ -489,7 +489,7 @@ parallel_vacuum_reset_dead_items(ParallelVacuumState *pvs)\\n> /*\\n> * Free the current tidstore and return allocated DSA segments to the\\n> * operating system. Then we recreate the tidstore with the same max_bytes\\n> - * limitation.\\n> + * limitation we just used.\\n>\\n> Nowadays, max_bytes is now more like a hint for tidstore, and not a\\n> limitation, right? Vacuum has the limitation.\\n\\nRight.\\n\\n> Maybe instead of \\\"with\\\",\\n> we should say \\\"passing the same limitation\\\".\\n\\nWill fix.\\n\\n>\\n> I wonder how \\\"di_info\\\" would look as \\\"dead_items_info\\\". I don't feel\\n> too strongly about it, though.\\n\\nAgreed.\\n\\n>\\n> I'm going to try additional regression tests, as mentioned, and try a\\n> couple benchmarks. It should be only a couple more days.\\n\\nThank you!\\n\\n> One thing that occurred to me: The radix tree regression tests only\\n> compile and run the local memory case. The tidstore commit would be\\n> the first time the buildfarm has seen the shared memory case, so we\\n> should look out for possible build failures of the same sort we saw\\n> with the the radix tree tests. I see you've already removed the\\n> problematic link_with command -- that's the kind of thing to\\n> double-check for.\\n\\nGood point, agreed. I'll double-check it again.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 13 Mar 2024 10:38:43 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 13, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> As I mentioned above, if we implement the test cases in C, we can use\\n> the debug-build array in the test code. And we won't use it in AND/OR\\n> operations tests in the future.\\n\\nThat's a really interesting idea, so I went ahead and tried that for\\nv71. This seems like a good basis for testing larger, randomized\\ninputs, once we decide how best to hide that from the expected output.\\nThe tests use SQL functions do_set_block_offsets() and\\ncheck_set_block_offsets(). The latter does two checks against a tid\\narray, and replaces test_dump_tids(). Funnily enough, the debug array\\nitself gave false failures when using a similar array in the test\\nharness, because it didn't know all the places where the array should\\nhave been sorted -- it only worked by chance before because of what\\norder things were done.\\n\\nI squashed everything from v70 and also took the liberty of switching\\non shared memory for tid store tests. The only reason we didn't do\\nthis with the radix tree tests is that the static attach/detach\\nfunctions would raise warnings since they are not used.\",\n \"msg_date\": \"Wed, 13 Mar 2024 18:04:51 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 13, 2024 at 8:05 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Mar 13, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > As I mentioned above, if we implement the test cases in C, we can use\\n> > the debug-build array in the test code. And we won't use it in AND/OR\\n> > operations tests in the future.\\n>\\n> That's a really interesting idea, so I went ahead and tried that for\\n> v71. This seems like a good basis for testing larger, randomized\\n> inputs, once we decide how best to hide that from the expected output.\\n> The tests use SQL functions do_set_block_offsets() and\\n> check_set_block_offsets(). The latter does two checks against a tid\\n> array, and replaces test_dump_tids().\\n\\nGreat! I think that's a very good starter.\\n\\nThe lookup_test() (and test_lookup_tids()) do also test that the\\nIsMember() function returns false as expected if the TID doesn't exist\\nin it, and probably we can do these tests in a C function too.\\n\\nBTW do we still want to test the tidstore by using a combination of\\nSQL functions? We might no longer need to input TIDs via a SQL\\nfunction.\\n\\n> Funnily enough, the debug array\\n> itself gave false failures when using a similar array in the test\\n> harness, because it didn't know all the places where the array should\\n> have been sorted -- it only worked by chance before because of what\\n> order things were done.\\n\\nGood catch, thanks.\\n\\n> I squashed everything from v70 and also took the liberty of switching\\n> on shared memory for tid store tests. The only reason we didn't do\\n> this with the radix tree tests is that the static attach/detach\\n> functions would raise warnings since they are not used.\\n\\nAgreed to test the tidstore on shared memory.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 13 Mar 2024 23:28:54 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 13, 2024 at 9:29 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Mar 13, 2024 at 8:05 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Wed, Mar 13, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > As I mentioned above, if we implement the test cases in C, we can use\\n> > > the debug-build array in the test code. And we won't use it in AND/OR\\n> > > operations tests in the future.\\n> >\\n> > That's a really interesting idea, so I went ahead and tried that for\\n> > v71. This seems like a good basis for testing larger, randomized\\n> > inputs, once we decide how best to hide that from the expected output.\\n> > The tests use SQL functions do_set_block_offsets() and\\n> > check_set_block_offsets(). The latter does two checks against a tid\\n> > array, and replaces test_dump_tids().\\n>\\n> Great! I think that's a very good starter.\\n>\\n> The lookup_test() (and test_lookup_tids()) do also test that the\\n> IsMember() function returns false as expected if the TID doesn't exist\\n> in it, and probably we can do these tests in a C function too.\\n>\\n> BTW do we still want to test the tidstore by using a combination of\\n> SQL functions? We might no longer need to input TIDs via a SQL\\n> function.\\n\\nI'm not sure. I stopped short of doing that to get feedback on this\\nmuch. One advantage with SQL functions is we can use generate_series\\nto easily input lists of blocks with different numbers and strides,\\nand array literals for offsets are a bit easier. What do you think?\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 07:59:15 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 9:59 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Mar 13, 2024 at 9:29 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Wed, Mar 13, 2024 at 8:05 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Wed, Mar 13, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > As I mentioned above, if we implement the test cases in C, we can use\\n> > > > the debug-build array in the test code. And we won't use it in AND/OR\\n> > > > operations tests in the future.\\n> > >\\n> > > That's a really interesting idea, so I went ahead and tried that for\\n> > > v71. This seems like a good basis for testing larger, randomized\\n> > > inputs, once we decide how best to hide that from the expected output.\\n> > > The tests use SQL functions do_set_block_offsets() and\\n> > > check_set_block_offsets(). The latter does two checks against a tid\\n> > > array, and replaces test_dump_tids().\\n> >\\n> > Great! I think that's a very good starter.\\n> >\\n> > The lookup_test() (and test_lookup_tids()) do also test that the\\n> > IsMember() function returns false as expected if the TID doesn't exist\\n> > in it, and probably we can do these tests in a C function too.\\n> >\\n> > BTW do we still want to test the tidstore by using a combination of\\n> > SQL functions? We might no longer need to input TIDs via a SQL\\n> > function.\\n>\\n> I'm not sure. I stopped short of doing that to get feedback on this\\n> much. One advantage with SQL functions is we can use generate_series\\n> to easily input lists of blocks with different numbers and strides,\\n> and array literals for offsets are a bit easier. What do you think?\\n\\nWhile I'm not a fan of the following part, I agree that it makes sense\\nto use SQL functions for test data generation:\\n\\n-- Constant values used in the tests.\\n\\\\set maxblkno 4294967295\\n-- The maximum number of heap tuples (MaxHeapTuplesPerPage) in 8kB block is 291.\\n-- We use a higher number to test tidstore.\\n\\\\set maxoffset 512\\n\\nIt would also be easier for developers to test the tidstore with their\\nown data set. So I agreed with the current approach; use SQL functions\\nfor data generation and do the actual tests inside C functions. Is it\\nconvenient for developers if we have functions like generate_tids()\\nand generate_random_tids() to generate TIDs so that they can pass them\\nto do_set_block_offsets()? Then they call check_set_block_offsets()\\nand others for actual data lookup and iteration tests.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 10:53:14 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 8:53 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 9:59 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > BTW do we still want to test the tidstore by using a combination of\\n> > > SQL functions? We might no longer need to input TIDs via a SQL\\n> > > function.\\n> >\\n> > I'm not sure. I stopped short of doing that to get feedback on this\\n> > much. One advantage with SQL functions is we can use generate_series\\n> > to easily input lists of blocks with different numbers and strides,\\n> > and array literals for offsets are a bit easier. What do you think?\\n>\\n> While I'm not a fan of the following part, I agree that it makes sense\\n> to use SQL functions for test data generation:\\n>\\n> -- Constant values used in the tests.\\n> \\\\set maxblkno 4294967295\\n> -- The maximum number of heap tuples (MaxHeapTuplesPerPage) in 8kB block is 291.\\n> -- We use a higher number to test tidstore.\\n> \\\\set maxoffset 512\\n\\nI'm not really a fan of these either, and could be removed a some\\npoint if we've done everything else nicely.\\n\\n> It would also be easier for developers to test the tidstore with their\\n> own data set. So I agreed with the current approach; use SQL functions\\n> for data generation and do the actual tests inside C functions.\\n\\nOkay, here's an another idea: Change test_lookup_tids() to be more\\ngeneral and put the validation down into C as well. First we save the\\nblocks from do_set_block_offsets() into a table, then with all those\\nblocks lookup a sufficiently-large range of possible offsets and save\\nfound values in another array. So the static items structure would\\nhave 3 arrays: inserts, successful lookups, and iteration (currently\\nthe iteration output is private to check_set_block_offsets(). Then\\nsort as needed and check they are all the same.\\n\\nFurther thought: We may not really need to test block numbers that\\nvigorously, since the radix tree tests should cover keys/values pretty\\nwell. The difference here is using bitmaps of tids and that should be\\nwell covered.\\n\\nLocally (not CI), we should try big inputs to make sure we can\\nactually go up to many GB -- it's easier and faster this way than\\nhaving vacuum give us a large data set.\\n\\n> Is it\\n> convenient for developers if we have functions like generate_tids()\\n> and generate_random_tids() to generate TIDs so that they can pass them\\n> to do_set_block_offsets()?\\n\\nI guess I don't see the advantage of adding a layer of indirection at\\nthis point, but it could be useful at a later time.\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 11:29:25 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 8:53 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 9:59 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > BTW do we still want to test the tidstore by using a combination of\\n> > > > SQL functions? We might no longer need to input TIDs via a SQL\\n> > > > function.\\n> > >\\n> > > I'm not sure. I stopped short of doing that to get feedback on this\\n> > > much. One advantage with SQL functions is we can use generate_series\\n> > > to easily input lists of blocks with different numbers and strides,\\n> > > and array literals for offsets are a bit easier. What do you think?\\n> >\\n> > While I'm not a fan of the following part, I agree that it makes sense\\n> > to use SQL functions for test data generation:\\n> >\\n> > -- Constant values used in the tests.\\n> > \\\\set maxblkno 4294967295\\n> > -- The maximum number of heap tuples (MaxHeapTuplesPerPage) in 8kB block is 291.\\n> > -- We use a higher number to test tidstore.\\n> > \\\\set maxoffset 512\\n>\\n> I'm not really a fan of these either, and could be removed a some\\n> point if we've done everything else nicely.\\n>\\n> > It would also be easier for developers to test the tidstore with their\\n> > own data set. So I agreed with the current approach; use SQL functions\\n> > for data generation and do the actual tests inside C functions.\\n>\\n> Okay, here's an another idea: Change test_lookup_tids() to be more\\n> general and put the validation down into C as well. First we save the\\n> blocks from do_set_block_offsets() into a table, then with all those\\n> blocks lookup a sufficiently-large range of possible offsets and save\\n> found values in another array. So the static items structure would\\n> have 3 arrays: inserts, successful lookups, and iteration (currently\\n> the iteration output is private to check_set_block_offsets(). Then\\n> sort as needed and check they are all the same.\\n\\nThat's a promising idea. We can use the same mechanism for randomized\\ntests too. If you're going to work on this, I'll do other tests on my\\nenvironment in the meantime.\\n\\n>\\n> Further thought: We may not really need to test block numbers that\\n> vigorously, since the radix tree tests should cover keys/values pretty\\n> well.\\n\\nAgreed. Probably boundary block numbers: 0, 1, MaxBlockNumber - 1, and\\nMaxBlockNumber, would be sufficient.\\n\\n> The difference here is using bitmaps of tids and that should be\\n> well covered.\\n\\nRight. We would need to test offset numbers vigorously instead.\\n\\n>\\n> Locally (not CI), we should try big inputs to make sure we can\\n> actually go up to many GB -- it's easier and faster this way than\\n> having vacuum give us a large data set.\\n\\nI'll do these tests.\\n\\n>\\n> > Is it\\n> > convenient for developers if we have functions like generate_tids()\\n> > and generate_random_tids() to generate TIDs so that they can pass them\\n> > to do_set_block_offsets()?\\n>\\n> I guess I don't see the advantage of adding a layer of indirection at\\n> this point, but it could be useful at a later time.\\n\\nAgreed.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 14:05:31 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > Okay, here's an another idea: Change test_lookup_tids() to be more\\n> > general and put the validation down into C as well. First we save the\\n> > blocks from do_set_block_offsets() into a table, then with all those\\n> > blocks lookup a sufficiently-large range of possible offsets and save\\n> > found values in another array. So the static items structure would\\n> > have 3 arrays: inserts, successful lookups, and iteration (currently\\n> > the iteration output is private to check_set_block_offsets(). Then\\n> > sort as needed and check they are all the same.\\n>\\n> That's a promising idea. We can use the same mechanism for randomized\\n> tests too. If you're going to work on this, I'll do other tests on my\\n> environment in the meantime.\\n\\nSome progress on this in v72 -- I tried first without using SQL to\\nsave the blocks, just using the unique blocks from the verification\\narray. It seems to work fine. Some open questions on the test module:\\n\\n- Since there are now three arrays we should reduce max bytes to\\nsomething smaller.\\n- Further on that, I'm not sure if the \\\"is full\\\" test is telling us\\nmuch. It seems we could make max bytes a static variable and set it to\\nthe size of the empty store. I'm guessing it wouldn't take much to add\\nenough tids so that the contexts need to allocate some blocks, and\\nthen it would appear full and we can test that. I've made it so all\\narrays repalloc when needed, just in case.\\n- Why are we switching to TopMemoryContext? It's not explained -- the\\ncomment only tells what the code is doing (which is obvious), but not\\nwhy.\\n- I'm not sure it's useful to keep test_lookup_tids() around. Since we\\nnow have a separate lookup test, the only thing it can tell us is that\\nlookups fail on an empty store. I arranged it so that\\ncheck_set_block_offsets() works on an empty store. Although that's\\neven more trivial, it's just reusing what we already need.\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 16:55:42 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 6:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > Okay, here's an another idea: Change test_lookup_tids() to be more\\n> > > general and put the validation down into C as well. First we save the\\n> > > blocks from do_set_block_offsets() into a table, then with all those\\n> > > blocks lookup a sufficiently-large range of possible offsets and save\\n> > > found values in another array. So the static items structure would\\n> > > have 3 arrays: inserts, successful lookups, and iteration (currently\\n> > > the iteration output is private to check_set_block_offsets(). Then\\n> > > sort as needed and check they are all the same.\\n> >\\n> > That's a promising idea. We can use the same mechanism for randomized\\n> > tests too. If you're going to work on this, I'll do other tests on my\\n> > environment in the meantime.\\n>\\n> Some progress on this in v72 -- I tried first without using SQL to\\n> save the blocks, just using the unique blocks from the verification\\n> array. It seems to work fine.\\n\\nThanks!\\n\\n>\\n> - Since there are now three arrays we should reduce max bytes to\\n> something smaller.\\n\\nAgreed.\\n\\n> - Further on that, I'm not sure if the \\\"is full\\\" test is telling us\\n> much. It seems we could make max bytes a static variable and set it to\\n> the size of the empty store. I'm guessing it wouldn't take much to add\\n> enough tids so that the contexts need to allocate some blocks, and\\n> then it would appear full and we can test that. I've made it so all\\n> arrays repalloc when needed, just in case.\\n\\nHow about using work_mem as max_bytes instead of having it as a static\\nvariable? In test_tidstore.sql we set work_mem before creating the\\ntidstore. It would make the tidstore more controllable by SQL queries.\\n\\n> - Why are we switching to TopMemoryContext? It's not explained -- the\\n> comment only tells what the code is doing (which is obvious), but not\\n> why.\\n\\nThis is because the tidstore needs to live across the transaction\\nboundary. We can use TopMemoryContext or CacheMemoryContext.\\n\\n> - I'm not sure it's useful to keep test_lookup_tids() around. Since we\\n> now have a separate lookup test, the only thing it can tell us is that\\n> lookups fail on an empty store. I arranged it so that\\n> check_set_block_offsets() works on an empty store. Although that's\\n> even more trivial, it's just reusing what we already need.\\n\\nAgreed.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 14 Mar 2024 21:03:27 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 9:03 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 6:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > Okay, here's an another idea: Change test_lookup_tids() to be more\\n> > > > general and put the validation down into C as well. First we save the\\n> > > > blocks from do_set_block_offsets() into a table, then with all those\\n> > > > blocks lookup a sufficiently-large range of possible offsets and save\\n> > > > found values in another array. So the static items structure would\\n> > > > have 3 arrays: inserts, successful lookups, and iteration (currently\\n> > > > the iteration output is private to check_set_block_offsets(). Then\\n> > > > sort as needed and check they are all the same.\\n> > >\\n> > > That's a promising idea. We can use the same mechanism for randomized\\n> > > tests too. If you're going to work on this, I'll do other tests on my\\n> > > environment in the meantime.\\n> >\\n> > Some progress on this in v72 -- I tried first without using SQL to\\n> > save the blocks, just using the unique blocks from the verification\\n> > array. It seems to work fine.\\n>\\n> Thanks!\\n>\\n> >\\n> > - Since there are now three arrays we should reduce max bytes to\\n> > something smaller.\\n>\\n> Agreed.\\n>\\n> > - Further on that, I'm not sure if the \\\"is full\\\" test is telling us\\n> > much. It seems we could make max bytes a static variable and set it to\\n> > the size of the empty store. I'm guessing it wouldn't take much to add\\n> > enough tids so that the contexts need to allocate some blocks, and\\n> > then it would appear full and we can test that. I've made it so all\\n> > arrays repalloc when needed, just in case.\\n>\\n> How about using work_mem as max_bytes instead of having it as a static\\n> variable? In test_tidstore.sql we set work_mem before creating the\\n> tidstore. It would make the tidstore more controllable by SQL queries.\\n>\\n> > - Why are we switching to TopMemoryContext? It's not explained -- the\\n> > comment only tells what the code is doing (which is obvious), but not\\n> > why.\\n>\\n> This is because the tidstore needs to live across the transaction\\n> boundary. We can use TopMemoryContext or CacheMemoryContext.\\n>\\n> > - I'm not sure it's useful to keep test_lookup_tids() around. Since we\\n> > now have a separate lookup test, the only thing it can tell us is that\\n> > lookups fail on an empty store. I arranged it so that\\n> > check_set_block_offsets() works on an empty store. Although that's\\n> > even more trivial, it's just reusing what we already need.\\n>\\n> Agreed.\\n>\\n\\nI have two questions on tidstore.c:\\n\\n+/*\\n+ * Set the given TIDs on the blkno to TidStore.\\n+ *\\n+ * NB: the offset numbers in offsets must be sorted in ascending order.\\n+ */\\n\\nDo we need some assertions to check if the given offset numbers are\\nsorted expectedly?\\n\\n---\\n+ if (TidStoreIsShared(ts))\\n+ found = shared_rt_set(ts->tree.shared, blkno, page);\\n+ else\\n+ found = local_rt_set(ts->tree.local, blkno, page);\\n+\\n+ Assert(!found);\\n\\nGiven TidStoreSetBlockOffsets() is designed to always set (i.e.\\noverwrite) the value, I think we should not expect that found is\\nalways false.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 15 Mar 2024 11:48:37 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 7:04 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 6:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > Okay, here's an another idea: Change test_lookup_tids() to be more\\n> > > > general and put the validation down into C as well. First we save the\\n> > > > blocks from do_set_block_offsets() into a table, then with all those\\n> > > > blocks lookup a sufficiently-large range of possible offsets and save\\n> > > > found values in another array. So the static items structure would\\n> > > > have 3 arrays: inserts, successful lookups, and iteration (currently\\n> > > > the iteration output is private to check_set_block_offsets(). Then\\n> > > > sort as needed and check they are all the same.\\n> > >\\n> > > That's a promising idea. We can use the same mechanism for randomized\\n> > > tests too. If you're going to work on this, I'll do other tests on my\\n> > > environment in the meantime.\\n> >\\n> > Some progress on this in v72 -- I tried first without using SQL to\\n> > save the blocks, just using the unique blocks from the verification\\n> > array. It seems to work fine.\\n>\\n> Thanks!\\n\\nSeems I forgot the attachment last time...there's more stuff now\\nanyway, based on discussion.\\n\\n> > - Since there are now three arrays we should reduce max bytes to\\n> > something smaller.\\n>\\n> Agreed.\\n\\nI went further than this, see below.\\n\\n> > - Further on that, I'm not sure if the \\\"is full\\\" test is telling us\\n> > much. It seems we could make max bytes a static variable and set it to\\n> > the size of the empty store. I'm guessing it wouldn't take much to add\\n> > enough tids so that the contexts need to allocate some blocks, and\\n> > then it would appear full and we can test that. I've made it so all\\n> > arrays repalloc when needed, just in case.\\n>\\n> How about using work_mem as max_bytes instead of having it as a static\\n> variable? In test_tidstore.sql we set work_mem before creating the\\n> tidstore. It would make the tidstore more controllable by SQL queries.\\n\\nMy complaint is that the \\\"is full\\\" test is trivial, and also strange\\nin that max_bytes is used for two unrelated things:\\n\\n- the initial size of the verification arrays, which was always larger\\nthan necessary, and now there are three of them\\n- the hint to TidStoreCreate to calculate its max block size / the\\nthreshold for being \\\"full\\\"\\n\\nTo make the \\\"is_full\\\" test slightly less trivial, my idea is to save\\nthe empty store size and later add enough tids so that it has to\\nallocate new blocks/DSA segments, which is not that many, and then it\\nwill appear full. I've done this and also separated the purpose of\\nvarious sizes in v72-0009/10.\\n\\nUsing actual work_mem seems a bit more difficult to make this work.\\n\\n> > - I'm not sure it's useful to keep test_lookup_tids() around. Since we\\n> > now have a separate lookup test, the only thing it can tell us is that\\n> > lookups fail on an empty store. I arranged it so that\\n> > check_set_block_offsets() works on an empty store. Although that's\\n> > even more trivial, it's just reusing what we already need.\\n>\\n> Agreed.\\n\\nRemoved in v72-0007\\n\\nOn Fri, Mar 15, 2024 at 9:49 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I have two questions on tidstore.c:\\n>\\n> +/*\\n> + * Set the given TIDs on the blkno to TidStore.\\n> + *\\n> + * NB: the offset numbers in offsets must be sorted in ascending order.\\n> + */\\n>\\n> Do we need some assertions to check if the given offset numbers are\\n> sorted expectedly?\\n\\nDone in v72-0008\\n\\n> ---\\n> + if (TidStoreIsShared(ts))\\n> + found = shared_rt_set(ts->tree.shared, blkno, page);\\n> + else\\n> + found = local_rt_set(ts->tree.local, blkno, page);\\n> +\\n> + Assert(!found);\\n>\\n> Given TidStoreSetBlockOffsets() is designed to always set (i.e.\\n> overwrite) the value, I think we should not expect that found is\\n> always false.\\n\\nI find that a puzzling statement, since 1) it was designed for\\ninsert-only workloads, not actual overwrite IIRC and 2) the tests will\\nnow fail if the same block is set twice, since we just switched the\\ntests to use a remnant of vacuum's old array. Having said that, I\\ndon't object to removing artificial barriers to using it for purposes\\nnot yet imagined, as long as test_tidstore.sql warns against that.\\n\\nGiven the above two things, I think this function's comment needs\\nstronger language about its limitations. Perhaps even mention that\\nit's intended for, and optimized for, vacuum. You and I have long\\nknown that tidstore would need a separate, more complex, function to\\nadd or remove individual tids from existing entries, but it might be\\ngood to have that documented.\\n\\nOther things:\\n\\nv72-0011: Test that zero offset raises an error.\\n\\nv72-0013: I had wanted to microbenchmark this, but since we are\\nrunning short of time I decided to skip that, so I want to revert some\\ncode to make it again more similar to the equivalent in tidbitmap.c.\\nIn the absence of evidence, it seems better to do it this way.\",\n \"msg_date\": \"Fri, 15 Mar 2024 14:36:10 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 15, 2024 at 4:36 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 7:04 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 6:55 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > >\\n> > > > On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > > Okay, here's an another idea: Change test_lookup_tids() to be more\\n> > > > > general and put the validation down into C as well. First we save the\\n> > > > > blocks from do_set_block_offsets() into a table, then with all those\\n> > > > > blocks lookup a sufficiently-large range of possible offsets and save\\n> > > > > found values in another array. So the static items structure would\\n> > > > > have 3 arrays: inserts, successful lookups, and iteration (currently\\n> > > > > the iteration output is private to check_set_block_offsets(). Then\\n> > > > > sort as needed and check they are all the same.\\n> > > >\\n> > > > That's a promising idea. We can use the same mechanism for randomized\\n> > > > tests too. If you're going to work on this, I'll do other tests on my\\n> > > > environment in the meantime.\\n> > >\\n> > > Some progress on this in v72 -- I tried first without using SQL to\\n> > > save the blocks, just using the unique blocks from the verification\\n> > > array. It seems to work fine.\\n> >\\n> > Thanks!\\n>\\n> Seems I forgot the attachment last time...there's more stuff now\\n> anyway, based on discussion.\\n\\nThank you for updating the patches!\\n\\nThe idea of using three TID arrays for the lookup test and iteration\\ntest looks good to me. I think we can add random-TIDs tests on top of\\nit.\\n\\n>\\n> > > - Since there are now three arrays we should reduce max bytes to\\n> > > something smaller.\\n> >\\n> > Agreed.\\n>\\n> I went further than this, see below.\\n>\\n> > > - Further on that, I'm not sure if the \\\"is full\\\" test is telling us\\n> > > much. It seems we could make max bytes a static variable and set it to\\n> > > the size of the empty store. I'm guessing it wouldn't take much to add\\n> > > enough tids so that the contexts need to allocate some blocks, and\\n> > > then it would appear full and we can test that. I've made it so all\\n> > > arrays repalloc when needed, just in case.\\n> >\\n> > How about using work_mem as max_bytes instead of having it as a static\\n> > variable? In test_tidstore.sql we set work_mem before creating the\\n> > tidstore. It would make the tidstore more controllable by SQL queries.\\n>\\n> My complaint is that the \\\"is full\\\" test is trivial, and also strange\\n> in that max_bytes is used for two unrelated things:\\n>\\n> - the initial size of the verification arrays, which was always larger\\n> than necessary, and now there are three of them\\n> - the hint to TidStoreCreate to calculate its max block size / the\\n> threshold for being \\\"full\\\"\\n>\\n> To make the \\\"is_full\\\" test slightly less trivial, my idea is to save\\n> the empty store size and later add enough tids so that it has to\\n> allocate new blocks/DSA segments, which is not that many, and then it\\n> will appear full. I've done this and also separated the purpose of\\n> various sizes in v72-0009/10.\\n\\nI see your point and the changes look good to me.\\n\\n> Using actual work_mem seems a bit more difficult to make this work.\\n\\nAgreed.\\n\\n>\\n>\\n> > ---\\n> > + if (TidStoreIsShared(ts))\\n> > + found = shared_rt_set(ts->tree.shared, blkno, page);\\n> > + else\\n> > + found = local_rt_set(ts->tree.local, blkno, page);\\n> > +\\n> > + Assert(!found);\\n> >\\n> > Given TidStoreSetBlockOffsets() is designed to always set (i.e.\\n> > overwrite) the value, I think we should not expect that found is\\n> > always false.\\n>\\n> I find that a puzzling statement, since 1) it was designed for\\n> insert-only workloads, not actual overwrite IIRC and 2) the tests will\\n> now fail if the same block is set twice, since we just switched the\\n> tests to use a remnant of vacuum's old array. Having said that, I\\n> don't object to removing artificial barriers to using it for purposes\\n> not yet imagined, as long as test_tidstore.sql warns against that.\\n\\nI think that if it supports only insert-only workload and expects the\\nsame block is set only once, it should raise an error rather than an\\nassertion. It's odd to me that the function fails only with an\\nassertion build assertions even though it actually works fine even in\\nthat case.\\n\\nAs for test_tidstore you're right that the test code doesn't handle\\nthe case where setting the same block twice. I think that there is no\\nproblem in the fixed-TIDs tests, but we would need something for\\nrandom-TIDs tests so that we don't set the same block twice. I guess\\nit could be trivial since we can use SQL queries to generate TIDs. I'm\\nnot sure how the random-TIDs tests would be like, but I think we can\\nuse SELECT DISTINCT to eliminate the duplicates of block numbers to\\nuse.\\n\\n>\\n> Given the above two things, I think this function's comment needs\\n> stronger language about its limitations. Perhaps even mention that\\n> it's intended for, and optimized for, vacuum. You and I have long\\n> known that tidstore would need a separate, more complex, function to\\n> add or remove individual tids from existing entries, but it might be\\n> good to have that documented.\\n\\nAgreed.\\n\\n>\\n> Other things:\\n>\\n> v72-0011: Test that zero offset raises an error.\\n>\\n> v72-0013: I had wanted to microbenchmark this, but since we are\\n> running short of time I decided to skip that, so I want to revert some\\n> code to make it again more similar to the equivalent in tidbitmap.c.\\n> In the absence of evidence, it seems better to do it this way.\\n\\nLGTM.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 15 Mar 2024 23:16:57 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 15, 2024 at 9:17 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Fri, Mar 15, 2024 at 4:36 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 7:04 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> > > Given TidStoreSetBlockOffsets() is designed to always set (i.e.\\n> > > overwrite) the value, I think we should not expect that found is\\n> > > always false.\\n> >\\n> > I find that a puzzling statement, since 1) it was designed for\\n> > insert-only workloads, not actual overwrite IIRC and 2) the tests will\\n> > now fail if the same block is set twice, since we just switched the\\n> > tests to use a remnant of vacuum's old array. Having said that, I\\n> > don't object to removing artificial barriers to using it for purposes\\n> > not yet imagined, as long as test_tidstore.sql warns against that.\\n>\\n> I think that if it supports only insert-only workload and expects the\\n> same block is set only once, it should raise an error rather than an\\n> assertion. It's odd to me that the function fails only with an\\n> assertion build assertions even though it actually works fine even in\\n> that case.\\n\\nAfter thinking some more, I think you're right -- it's too\\nheavy-handed to throw an error/assert and a public function shouldn't\\nmake assumptions about the caller. It's probably just a matter of\\ndocumenting the function (and it's lack of generality), and the tests\\n(which are based on the thing we're replacing).\\n\\n> As for test_tidstore you're right that the test code doesn't handle\\n> the case where setting the same block twice. I think that there is no\\n> problem in the fixed-TIDs tests, but we would need something for\\n> random-TIDs tests so that we don't set the same block twice. I guess\\n> it could be trivial since we can use SQL queries to generate TIDs. I'm\\n> not sure how the random-TIDs tests would be like, but I think we can\\n> use SELECT DISTINCT to eliminate the duplicates of block numbers to\\n> use.\\n\\nAlso, I don't think we need random blocks, since the radix tree tests\\nexcercise that heavily already.\\n\\nRandom offsets is what I was thinking of (if made distinct and\\nordered), but even there the code is fairy trivial, so I don't have a\\nstrong feeling about it.\\n\\n> > Given the above two things, I think this function's comment needs\\n> > stronger language about its limitations. Perhaps even mention that\\n> > it's intended for, and optimized for, vacuum. You and I have long\\n> > known that tidstore would need a separate, more complex, function to\\n> > add or remove individual tids from existing entries, but it might be\\n> > good to have that documented.\\n>\\n> Agreed.\\n\\nHow about this:\\n\\n /*\\n- * Set the given TIDs on the blkno to TidStore.\\n+ * Create or replace an entry for the given block and array of offsets\\n *\\n- * NB: the offset numbers in offsets must be sorted in ascending order.\\n+ * NB: This function is designed and optimized for vacuum's heap scanning\\n+ * phase, so has some limitations:\\n+ * - The offset numbers in \\\"offsets\\\" must be sorted in ascending order.\\n+ * - If the block number already exists, the entry will be replaced --\\n+ * there is no way to add or remove offsets from an entry.\\n */\\n void\\n TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n\\nI think we can stop including the debug-tid-store patch for CI now.\\nThat would allow getting rid of some unnecessary variables. More\\ncomments:\\n\\n+ * Prepare to iterate through a TidStore. Since the radix tree is locked during\\n+ * the iteration, TidStoreEndIterate() needs to be called when finished.\\n\\n+ * Concurrent updates during the iteration will be blocked when inserting a\\n+ * key-value to the radix tree.\\n\\nThis is outdated. Locking is optional. The remaining real reason now\\nis that TidStoreEndIterate needs to free memory. We probably need to\\nsay something about locking, too, but not this.\\n\\n+ * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n+ * in one block. We return the block numbers in ascending order and the offset\\n+ * numbers in each result is also sorted in ascending order.\\n+ */\\n+TidStoreIterResult *\\n+TidStoreIterateNext(TidStoreIter *iter)\\n\\nThe wording is a bit awkward.\\n\\n+/*\\n+ * Finish an iteration over TidStore. This needs to be called after finishing\\n+ * or when existing an iteration.\\n+ */\\n\\ns/existing/exiting/ ?\\n\\nIt seems to say we need to finish after finishing. Maybe more precise wording.\\n\\n+/* Extract TIDs from the given key-value pair */\\n+static void\\n+tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key,\\nBlocktableEntry *page)\\n\\nThis is a leftover from the old encoding scheme. This should really\\ntake a \\\"BlockNumber blockno\\\" not a \\\"key\\\", and the only call site\\nshould probably cast the uint64 to BlockNumber.\\n\\n+ * tidstore.h\\n+ * Tid storage.\\n+ *\\n+ *\\n+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group\\n\\nUpdate year.\\n\\n+typedef struct BlocktableEntry\\n+{\\n+ uint16 nwords;\\n+ bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n+} BlocktableEntry;\\n\\nIn my WIP for runtime-embeddable offsets, nwords needs to be one byte.\\nThat doesn't have any real-world affect on the largest offset\\nencountered, and only in 32-bit builds with 32kB block size would the\\ntheoretical max change at all. To be precise, we could use in the\\nMaxBlocktableEntrySize calculation:\\n\\nMin(MaxOffsetNumber, BITS_PER_BITMAPWORD * PG_INT8_MAX - 1);\\n\\nTests: I never got rid of maxblkno and maxoffset, in case you wanted\\nto do that. And as discussed above, maybe\\n\\n-- Note: The test code use an array of TIDs for verification similar\\n-- to vacuum's dead item array pre-PG17. To avoid adding duplicates,\\n-- each call to do_set_block_offsets() should use different block\\n-- numbers.\\n\\n\\n\",\n \"msg_date\": \"Sun, 17 Mar 2024 09:46:13 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Mar 17, 2024 at 11:46 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Mar 15, 2024 at 9:17 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Fri, Mar 15, 2024 at 4:36 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Thu, Mar 14, 2024 at 7:04 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > > Given TidStoreSetBlockOffsets() is designed to always set (i.e.\\n> > > > overwrite) the value, I think we should not expect that found is\\n> > > > always false.\\n> > >\\n> > > I find that a puzzling statement, since 1) it was designed for\\n> > > insert-only workloads, not actual overwrite IIRC and 2) the tests will\\n> > > now fail if the same block is set twice, since we just switched the\\n> > > tests to use a remnant of vacuum's old array. Having said that, I\\n> > > don't object to removing artificial barriers to using it for purposes\\n> > > not yet imagined, as long as test_tidstore.sql warns against that.\\n> >\\n> > I think that if it supports only insert-only workload and expects the\\n> > same block is set only once, it should raise an error rather than an\\n> > assertion. It's odd to me that the function fails only with an\\n> > assertion build assertions even though it actually works fine even in\\n> > that case.\\n>\\n> After thinking some more, I think you're right -- it's too\\n> heavy-handed to throw an error/assert and a public function shouldn't\\n> make assumptions about the caller. It's probably just a matter of\\n> documenting the function (and it's lack of generality), and the tests\\n> (which are based on the thing we're replacing).\\n\\nRemoved 'found' in 0003 patch.\\n\\n>\\n> > As for test_tidstore you're right that the test code doesn't handle\\n> > the case where setting the same block twice. I think that there is no\\n> > problem in the fixed-TIDs tests, but we would need something for\\n> > random-TIDs tests so that we don't set the same block twice. I guess\\n> > it could be trivial since we can use SQL queries to generate TIDs. I'm\\n> > not sure how the random-TIDs tests would be like, but I think we can\\n> > use SELECT DISTINCT to eliminate the duplicates of block numbers to\\n> > use.\\n>\\n> Also, I don't think we need random blocks, since the radix tree tests\\n> excercise that heavily already.\\n>\\n> Random offsets is what I was thinking of (if made distinct and\\n> ordered), but even there the code is fairy trivial, so I don't have a\\n> strong feeling about it.\\n\\nAgreed.\\n\\n>\\n> > > Given the above two things, I think this function's comment needs\\n> > > stronger language about its limitations. Perhaps even mention that\\n> > > it's intended for, and optimized for, vacuum. You and I have long\\n> > > known that tidstore would need a separate, more complex, function to\\n> > > add or remove individual tids from existing entries, but it might be\\n> > > good to have that documented.\\n> >\\n> > Agreed.\\n>\\n> How about this:\\n>\\n> /*\\n> - * Set the given TIDs on the blkno to TidStore.\\n> + * Create or replace an entry for the given block and array of offsets\\n> *\\n> - * NB: the offset numbers in offsets must be sorted in ascending order.\\n> + * NB: This function is designed and optimized for vacuum's heap scanning\\n> + * phase, so has some limitations:\\n> + * - The offset numbers in \\\"offsets\\\" must be sorted in ascending order.\\n> + * - If the block number already exists, the entry will be replaced --\\n> + * there is no way to add or remove offsets from an entry.\\n> */\\n> void\\n> TidStoreSetBlockOffsets(TidStore *ts, BlockNumber blkno, OffsetNumber *offsets,\\n\\nLooks good.\\n\\n>\\n> I think we can stop including the debug-tid-store patch for CI now.\\n> That would allow getting rid of some unnecessary variables.\\n\\nAgreed.\\n\\n>\\n> + * Prepare to iterate through a TidStore. Since the radix tree is locked during\\n> + * the iteration, TidStoreEndIterate() needs to be called when finished.\\n>\\n> + * Concurrent updates during the iteration will be blocked when inserting a\\n> + * key-value to the radix tree.\\n>\\n> This is outdated. Locking is optional. The remaining real reason now\\n> is that TidStoreEndIterate needs to free memory. We probably need to\\n> say something about locking, too, but not this.\\n\\nFixed.\\n\\n>\\n> + * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n> + * in one block. We return the block numbers in ascending order and the offset\\n> + * numbers in each result is also sorted in ascending order.\\n> + */\\n> +TidStoreIterResult *\\n> +TidStoreIterateNext(TidStoreIter *iter)\\n>\\n> The wording is a bit awkward.\\n\\nFixed.\\n\\n>\\n> +/*\\n> + * Finish an iteration over TidStore. This needs to be called after finishing\\n> + * or when existing an iteration.\\n> + */\\n>\\n> s/existing/exiting/ ?\\n>\\n> It seems to say we need to finish after finishing. Maybe more precise wording.\\n\\nFixed.\\n\\n>\\n> +/* Extract TIDs from the given key-value pair */\\n> +static void\\n> +tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key,\\n> BlocktableEntry *page)\\n>\\n> This is a leftover from the old encoding scheme. This should really\\n> take a \\\"BlockNumber blockno\\\" not a \\\"key\\\", and the only call site\\n> should probably cast the uint64 to BlockNumber.\\n\\nFixed.\\n\\n>\\n> + * tidstore.h\\n> + * Tid storage.\\n> + *\\n> + *\\n> + * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group\\n>\\n> Update year.\\n\\nUpdated.\\n\\n>\\n> +typedef struct BlocktableEntry\\n> +{\\n> + uint16 nwords;\\n> + bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n> +} BlocktableEntry;\\n>\\n> In my WIP for runtime-embeddable offsets, nwords needs to be one byte.\\n> That doesn't have any real-world affect on the largest offset\\n> encountered, and only in 32-bit builds with 32kB block size would the\\n> theoretical max change at all. To be precise, we could use in the\\n> MaxBlocktableEntrySize calculation:\\n>\\n> Min(MaxOffsetNumber, BITS_PER_BITMAPWORD * PG_INT8_MAX - 1);\\n\\nI don't get this expression. Making the nwords one byte works well?\\nWith 8kB blocks, MaxOffsetNumber is 2048 and it requires 256\\nbitmapword entries on 64-bit OS or 512 bitmapword entries on 32-bit\\nOS, respectively. One byte nwrods variable seems not to be sufficient\\nfor both cases. Also, where does the expression \\\"BITS_PER_BITMAPWORD *\\nPG_INT8_MAX - 1\\\" come from?\\n\\n>\\n> Tests: I never got rid of maxblkno and maxoffset, in case you wanted\\n> to do that. And as discussed above, maybe\\n>\\n> -- Note: The test code use an array of TIDs for verification similar\\n> -- to vacuum's dead item array pre-PG17. To avoid adding duplicates,\\n> -- each call to do_set_block_offsets() should use different block\\n> -- numbers.\\n\\nI've added this comment on top of the .sql file.\\n\\nI've attached the new patch sets. The summary of updates is:\\n\\n- Squashed all updates of v72\\n- 0004 and 0005 are updates for test_tidstore.sql. Particularly the\\n0005 patch adds randomized TID tests.\\n- 0006 addresses review comments above.\\n- 0007 and 0008 patches are pgindent stuff.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 18 Mar 2024 13:12:07 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 18, 2024 at 11:12 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Sun, Mar 17, 2024 at 11:46 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > Random offsets is what I was thinking of (if made distinct and\\n> > ordered), but even there the code is fairy trivial, so I don't have a\\n> > strong feeling about it.\\n>\\n> Agreed.\\n\\nLooks good.\\n\\nA related thing I should mention is that the tests which look up all\\npossible offsets are really expensive with the number of blocks we're\\nusing now (assert build):\\n\\nv70 0.33s\\nv72 1.15s\\nv73 1.32\\n\\nTo trim that back, I think we should give up on using shared memory\\nfor the is-full test: We can cause aset to malloc a new block with a\\nlot fewer entries. In the attached, this brings it back down to 0.43s.\\nIt might also be worth reducing the number of blocks in the random\\ntest -- multiple runs will have different offsets anyway.\\n\\n> > I think we can stop including the debug-tid-store patch for CI now.\\n> > That would allow getting rid of some unnecessary variables.\\n>\\n> Agreed.\\n\\nOkay, all that remains here is to get rid of those variables (might be\\njust one).\\n\\n> > + * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n> > + * in one block. We return the block numbers in ascending order and the offset\\n> > + * numbers in each result is also sorted in ascending order.\\n> > + */\\n> > +TidStoreIterResult *\\n> > +TidStoreIterateNext(TidStoreIter *iter)\\n> >\\n> > The wording is a bit awkward.\\n>\\n> Fixed.\\n\\n- * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n- * in one block. We return the block numbers in ascending order and the offset\\n- * numbers in each result is also sorted in ascending order.\\n+ * Scan the TidStore and return the TIDs of the next block. The returned block\\n+ * numbers is sorted in ascending order, and the offset numbers in each result\\n+ * is also sorted in ascending order.\\n\\nBetter, but it's still not very clear. Maybe \\\"The offsets in each\\niteration result are ordered, as are the block numbers over all\\niterations.\\\"\\n\\n> > +/* Extract TIDs from the given key-value pair */\\n> > +static void\\n> > +tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key,\\n> > BlocktableEntry *page)\\n> >\\n> > This is a leftover from the old encoding scheme. This should really\\n> > take a \\\"BlockNumber blockno\\\" not a \\\"key\\\", and the only call site\\n> > should probably cast the uint64 to BlockNumber.\\n>\\n> Fixed.\\n\\nThis part looks good. I didn't notice earlier, but this comment has a\\nsimilar issue\\n\\n@@ -384,14 +391,15 @@ TidStoreIterateNext(TidStoreIter *iter)\\n return NULL;\\n\\n /* Collect TIDs extracted from the key-value pair */\\n- tidstore_iter_extract_tids(iter, key, page);\\n+ tidstore_iter_extract_tids(iter, (BlockNumber) key, page);\\n\\n...\\\"extracted\\\" was once a separate operation. I think just removing\\nthat one word is enough to update it.\\n\\nSome other review on code comments:\\n\\nv73-0001:\\n\\n+ /* Enlarge the TID array if necessary */\\n\\nIt's \\\"arrays\\\" now.\\n\\nv73-0005:\\n\\n+-- Random TIDs test. We insert TIDs for 1000 blocks. Each block has\\n+-- different randon 100 offset numbers each other.\\n\\nThe numbers are obvious from the query. Maybe just mention that the\\noffsets are randomized and must be unique and ordered.\\n\\n+ * The caller is responsible for release any locks.\\n\\n\\\"releasing\\\"\\n\\n> > +typedef struct BlocktableEntry\\n> > +{\\n> > + uint16 nwords;\\n> > + bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n> > +} BlocktableEntry;\\n> >\\n> > In my WIP for runtime-embeddable offsets, nwords needs to be one byte.\\n\\nI should be more clear here: nwords fitting into one byte allows 3\\nembedded offsets (1 on 32-bit platforms, which is good for testing at\\nleast). With uint16 nwords that reduces to 2 (none on 32-bit\\nplatforms). Further, after the current patch series is fully\\ncommitted, I plan to split the embedded-offset patch into two parts:\\nThe first would store the offsets in the header, but would still need\\na (smaller) allocation. The second would embed them in the child\\npointer. Only the second patch will care about the size of nwords\\nbecause it needs to reserve a byte for the pointer tag.\\n\\n> > That doesn't have any real-world affect on the largest offset\\n> > encountered, and only in 32-bit builds with 32kB block size would the\\n> > theoretical max change at all. To be precise, we could use in the\\n> > MaxBlocktableEntrySize calculation:\\n> >\\n> > Min(MaxOffsetNumber, BITS_PER_BITMAPWORD * PG_INT8_MAX - 1);\\n>\\n> I don't get this expression. Making the nwords one byte works well?\\n> With 8kB blocks, MaxOffsetNumber is 2048 and it requires 256\\n> bitmapword entries on 64-bit OS or 512 bitmapword entries on 32-bit\\n> OS, respectively. One byte nwrods variable seems not to be sufficient\\n\\nI believe there is confusion between bitmap words and bytes:\\n2048 / 64 = 32 words = 256 bytes\\n\\nIt used to be max tuples per (heap) page, but we wanted a simple way\\nto make this independent of heap. I believe we won't need to ever\\nstore the actual MaxOffsetNumber, although we technically still could\\nwith a one-byte type and 32kB pages, at least on 64-bit platforms.\\n\\n> for both cases. Also, where does the expression \\\"BITS_PER_BITMAPWORD *\\n> PG_INT8_MAX - 1\\\" come from?\\n\\n127 words, each with 64 (or 32) bits. The zero bit is not a valid\\noffset, so subtract one. And I used signed type in case there was a\\nneed for -1 to mean something.\",\n \"msg_date\": \"Tue, 19 Mar 2024 06:35:39 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 19, 2024 at 8:35 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Mar 18, 2024 at 11:12 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Sun, Mar 17, 2024 at 11:46 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > Random offsets is what I was thinking of (if made distinct and\\n> > > ordered), but even there the code is fairy trivial, so I don't have a\\n> > > strong feeling about it.\\n> >\\n> > Agreed.\\n>\\n> Looks good.\\n>\\n> A related thing I should mention is that the tests which look up all\\n> possible offsets are really expensive with the number of blocks we're\\n> using now (assert build):\\n>\\n> v70 0.33s\\n> v72 1.15s\\n> v73 1.32\\n>\\n> To trim that back, I think we should give up on using shared memory\\n> for the is-full test: We can cause aset to malloc a new block with a\\n> lot fewer entries. In the attached, this brings it back down to 0.43s.\\n\\nLooks good. Agreed with this change.\\n\\n> It might also be worth reducing the number of blocks in the random\\n> test -- multiple runs will have different offsets anyway.\\n\\nYes. If we reduce the number of blocks from 1000 to 100, the\\nregression test took on my environment:\\n\\n1000 blocks : 516 ms\\n100 blocks : 228 ms\\n\\n>\\n> > > I think we can stop including the debug-tid-store patch for CI now.\\n> > > That would allow getting rid of some unnecessary variables.\\n> >\\n> > Agreed.\\n>\\n> Okay, all that remains here is to get rid of those variables (might be\\n> just one).\\n\\nRemoved some unnecessary variables in 0002 patch.\\n\\n>\\n> > > + * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n> > > + * in one block. We return the block numbers in ascending order and the offset\\n> > > + * numbers in each result is also sorted in ascending order.\\n> > > + */\\n> > > +TidStoreIterResult *\\n> > > +TidStoreIterateNext(TidStoreIter *iter)\\n> > >\\n> > > The wording is a bit awkward.\\n> >\\n> > Fixed.\\n>\\n> - * Scan the TidStore and return a pointer to TidStoreIterResult that has TIDs\\n> - * in one block. We return the block numbers in ascending order and the offset\\n> - * numbers in each result is also sorted in ascending order.\\n> + * Scan the TidStore and return the TIDs of the next block. The returned block\\n> + * numbers is sorted in ascending order, and the offset numbers in each result\\n> + * is also sorted in ascending order.\\n>\\n> Better, but it's still not very clear. Maybe \\\"The offsets in each\\n> iteration result are ordered, as are the block numbers over all\\n> iterations.\\\"\\n\\nThanks, fixed.\\n\\n>\\n> > > +/* Extract TIDs from the given key-value pair */\\n> > > +static void\\n> > > +tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key,\\n> > > BlocktableEntry *page)\\n> > >\\n> > > This is a leftover from the old encoding scheme. This should really\\n> > > take a \\\"BlockNumber blockno\\\" not a \\\"key\\\", and the only call site\\n> > > should probably cast the uint64 to BlockNumber.\\n> >\\n> > Fixed.\\n>\\n> This part looks good. I didn't notice earlier, but this comment has a\\n> similar issue\\n>\\n> @@ -384,14 +391,15 @@ TidStoreIterateNext(TidStoreIter *iter)\\n> return NULL;\\n>\\n> /* Collect TIDs extracted from the key-value pair */\\n> - tidstore_iter_extract_tids(iter, key, page);\\n> + tidstore_iter_extract_tids(iter, (BlockNumber) key, page);\\n>\\n> ...\\\"extracted\\\" was once a separate operation. I think just removing\\n> that one word is enough to update it.\\n\\nFixed.\\n\\n>\\n> Some other review on code comments:\\n>\\n> v73-0001:\\n>\\n> + /* Enlarge the TID array if necessary */\\n>\\n> It's \\\"arrays\\\" now.\\n>\\n> v73-0005:\\n>\\n> +-- Random TIDs test. We insert TIDs for 1000 blocks. Each block has\\n> +-- different randon 100 offset numbers each other.\\n>\\n> The numbers are obvious from the query. Maybe just mention that the\\n> offsets are randomized and must be unique and ordered.\\n>\\n> + * The caller is responsible for release any locks.\\n>\\n> \\\"releasing\\\"\\n\\nFixed.\\n\\n>\\n> > > +typedef struct BlocktableEntry\\n> > > +{\\n> > > + uint16 nwords;\\n> > > + bitmapword words[FLEXIBLE_ARRAY_MEMBER];\\n> > > +} BlocktableEntry;\\n> > >\\n> > > In my WIP for runtime-embeddable offsets, nwords needs to be one byte.\\n>\\n> I should be more clear here: nwords fitting into one byte allows 3\\n> embedded offsets (1 on 32-bit platforms, which is good for testing at\\n> least). With uint16 nwords that reduces to 2 (none on 32-bit\\n> platforms). Further, after the current patch series is fully\\n> committed, I plan to split the embedded-offset patch into two parts:\\n> The first would store the offsets in the header, but would still need\\n> a (smaller) allocation. The second would embed them in the child\\n> pointer. Only the second patch will care about the size of nwords\\n> because it needs to reserve a byte for the pointer tag.\\n\\nThank you for the clarification.\\n\\n>\\n> > > That doesn't have any real-world affect on the largest offset\\n> > > encountered, and only in 32-bit builds with 32kB block size would the\\n> > > theoretical max change at all. To be precise, we could use in the\\n> > > MaxBlocktableEntrySize calculation:\\n> > >\\n> > > Min(MaxOffsetNumber, BITS_PER_BITMAPWORD * PG_INT8_MAX - 1);\\n> >\\n> > I don't get this expression. Making the nwords one byte works well?\\n> > With 8kB blocks, MaxOffsetNumber is 2048 and it requires 256\\n> > bitmapword entries on 64-bit OS or 512 bitmapword entries on 32-bit\\n> > OS, respectively. One byte nwrods variable seems not to be sufficient\\n>\\n> I believe there is confusion between bitmap words and bytes:\\n> 2048 / 64 = 32 words = 256 bytes\\n\\nOops, you're right.\\n\\n>\\n> It used to be max tuples per (heap) page, but we wanted a simple way\\n> to make this independent of heap. I believe we won't need to ever\\n> store the actual MaxOffsetNumber, although we technically still could\\n> with a one-byte type and 32kB pages, at least on 64-bit platforms.\\n>\\n> > for both cases. Also, where does the expression \\\"BITS_PER_BITMAPWORD *\\n> > PG_INT8_MAX - 1\\\" come from?\\n>\\n> 127 words, each with 64 (or 32) bits. The zero bit is not a valid\\n> offset, so subtract one. And I used signed type in case there was a\\n> need for -1 to mean something.\\n\\nOkay, I missed that we want to change nwords from uint8 to int8.\\n\\nSo the MaxBlocktableEntrySize calculation would be as follows?\\n\\n#define MaxBlocktableEntrySize \\\\\\n offsetof(BlocktableEntry, words) + \\\\\\n (sizeof(bitmapword) * \\\\\\n WORDS_PER_PAGE(Min(MaxOffsetNumber, \\\\\\n BITS_PER_BITMAPWORD * PG_INT8_MAX - 1))))\\n\\nI've made this change in the 0003 patch.\\n\\nWhile reviewing the vacuum patch, I realized that we always pass\\nLWTRANCHE_SHARED_TIDSTORE to RT_CREATE(), and the wait event related\\nto the tidstore is therefore always the same. I think it would be\\nbetter to make the caller of TidStoreCreate() specify the tranch_id\\nand pass it to RT_CREATE(). That way, the caller can specify their own\\nwait event for tidstore. The 0008 patch tried this idea. dshash.c does\\nthe same idea.\\n\\nOther patches are minor updates for tidstore and vacuum patches.\\n\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Tue, 19 Mar 2024 12:23:47 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 19, 2024 at 10:24 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Tue, Mar 19, 2024 at 8:35 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 18, 2024 at 11:12 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Sun, Mar 17, 2024 at 11:46 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > It might also be worth reducing the number of blocks in the random\\n> > test -- multiple runs will have different offsets anyway.\\n>\\n> Yes. If we reduce the number of blocks from 1000 to 100, the\\n> regression test took on my environment:\\n>\\n> 1000 blocks : 516 ms\\n> 100 blocks : 228 ms\\n\\nSounds good.\\n\\n> Removed some unnecessary variables in 0002 patch.\\n\\nLooks good.\\n\\n> So the MaxBlocktableEntrySize calculation would be as follows?\\n>\\n> #define MaxBlocktableEntrySize \\\\\\n> offsetof(BlocktableEntry, words) + \\\\\\n> (sizeof(bitmapword) * \\\\\\n> WORDS_PER_PAGE(Min(MaxOffsetNumber, \\\\\\n> BITS_PER_BITMAPWORD * PG_INT8_MAX - 1))))\\n>\\n> I've made this change in the 0003 patch.\\n\\nThis is okay, but one side effect is that we have both an assert and\\nan elog, for different limits. I think we'll need a separate #define\\nto help. But for now, I don't want to hold up tidstore further with\\nthis because I believe almost everything else in v74 is in pretty good\\nshape. I'll save this for later as a part of the optimization I\\nproposed.\\n\\nRemaining things I noticed:\\n\\n+#define RT_PREFIX local_rt\\n+#define RT_PREFIX shared_rt\\n\\nPrefixes for simplehash, for example, don't have \\\"sh\\\" -- maybe \\\"local/shared_ts\\\"\\n\\n+ /* MemoryContext where the radix tree uses */\\n\\ns/where/that/\\n\\n+/*\\n+ * Lock support functions.\\n+ *\\n+ * We can use the radix tree's lock for shared TidStore as the data we\\n+ * need to protect is only the shared radix tree.\\n+ */\\n+void\\n+TidStoreLockExclusive(TidStore *ts)\\n\\nTalking about multiple things, so maybe a blank line after the comment.\\n\\nWith those, I think you can go ahead and squash all the tidstore\\npatches except for 0003 and commit it.\\n\\n> While reviewing the vacuum patch, I realized that we always pass\\n> LWTRANCHE_SHARED_TIDSTORE to RT_CREATE(), and the wait event related\\n> to the tidstore is therefore always the same. I think it would be\\n> better to make the caller of TidStoreCreate() specify the tranch_id\\n> and pass it to RT_CREATE(). That way, the caller can specify their own\\n> wait event for tidstore. The 0008 patch tried this idea. dshash.c does\\n> the same idea.\\n\\nSounds reasonable. I'll just note that src/include/storage/lwlock.h\\nstill has an entry for LWTRANCHE_SHARED_TIDSTORE.\\n\\n\\n\",\n \"msg_date\": \"Tue, 19 Mar 2024 16:40:06 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Tue, Mar 19, 2024 at 6:40 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Tue, Mar 19, 2024 at 10:24 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Tue, Mar 19, 2024 at 8:35 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Mon, Mar 18, 2024 at 11:12 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > > >\\n> > > > On Sun, Mar 17, 2024 at 11:46 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > It might also be worth reducing the number of blocks in the random\\n> > > test -- multiple runs will have different offsets anyway.\\n> >\\n> > Yes. If we reduce the number of blocks from 1000 to 100, the\\n> > regression test took on my environment:\\n> >\\n> > 1000 blocks : 516 ms\\n> > 100 blocks : 228 ms\\n>\\n> Sounds good.\\n>\\n> > Removed some unnecessary variables in 0002 patch.\\n>\\n> Looks good.\\n>\\n> > So the MaxBlocktableEntrySize calculation would be as follows?\\n> >\\n> > #define MaxBlocktableEntrySize \\\\\\n> > offsetof(BlocktableEntry, words) + \\\\\\n> > (sizeof(bitmapword) * \\\\\\n> > WORDS_PER_PAGE(Min(MaxOffsetNumber, \\\\\\n> > BITS_PER_BITMAPWORD * PG_INT8_MAX - 1))))\\n> >\\n> > I've made this change in the 0003 patch.\\n>\\n> This is okay, but one side effect is that we have both an assert and\\n> an elog, for different limits. I think we'll need a separate #define\\n> to help. But for now, I don't want to hold up tidstore further with\\n> this because I believe almost everything else in v74 is in pretty good\\n> shape. I'll save this for later as a part of the optimization I\\n> proposed.\\n>\\n> Remaining things I noticed:\\n>\\n> +#define RT_PREFIX local_rt\\n> +#define RT_PREFIX shared_rt\\n>\\n> Prefixes for simplehash, for example, don't have \\\"sh\\\" -- maybe \\\"local/shared_ts\\\"\\n>\\n> + /* MemoryContext where the radix tree uses */\\n>\\n> s/where/that/\\n>\\n> +/*\\n> + * Lock support functions.\\n> + *\\n> + * We can use the radix tree's lock for shared TidStore as the data we\\n> + * need to protect is only the shared radix tree.\\n> + */\\n> +void\\n> +TidStoreLockExclusive(TidStore *ts)\\n>\\n> Talking about multiple things, so maybe a blank line after the comment.\\n>\\n> With those, I think you can go ahead and squash all the tidstore\\n> patches except for 0003 and commit it.\\n>\\n> > While reviewing the vacuum patch, I realized that we always pass\\n> > LWTRANCHE_SHARED_TIDSTORE to RT_CREATE(), and the wait event related\\n> > to the tidstore is therefore always the same. I think it would be\\n> > better to make the caller of TidStoreCreate() specify the tranch_id\\n> > and pass it to RT_CREATE(). That way, the caller can specify their own\\n> > wait event for tidstore. The 0008 patch tried this idea. dshash.c does\\n> > the same idea.\\n>\\n> Sounds reasonable. I'll just note that src/include/storage/lwlock.h\\n> still has an entry for LWTRANCHE_SHARED_TIDSTORE.\\n\\nThank you. I've incorporated all the comments above. I've attached the\\nlatest patches, and am going to push them (one by one) after\\nself-review again.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 20 Mar 2024 01:40:25 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > Locally (not CI), we should try big inputs to make sure we can\\n> > actually go up to many GB -- it's easier and faster this way than\\n> > having vacuum give us a large data set.\\n>\\n> I'll do these tests.\\n\\nI just remembered this -- did any of this kind of testing happen? I\\ncan do it as well.\\n\\n> Thank you. I've incorporated all the comments above. I've attached the\\n> latest patches, and am going to push them (one by one) after\\n> self-review again.\\n\\nOne more cosmetic thing in 0001 that caught my eye:\\n\\ndiff --git a/src/backend/access/common/Makefile\\nb/src/backend/access/common/Makefile\\nindex b9aff0ccfd..67b8cc6108 100644\\n--- a/src/backend/access/common/Makefile\\n+++ b/src/backend/access/common/Makefile\\n@@ -27,6 +27,7 @@ OBJS = \\\\\\n syncscan.o \\\\\\n toast_compression.o \\\\\\n toast_internals.o \\\\\\n+ tidstore.o \\\\\\n tupconvert.o \\\\\\n tupdesc.o\\n\\ndiff --git a/src/backend/access/common/meson.build\\nb/src/backend/access/common/meson.build\\nindex 725041a4ce..a02397855e 100644\\n--- a/src/backend/access/common/meson.build\\n+++ b/src/backend/access/common/meson.build\\n@@ -15,6 +15,7 @@ backend_sources += files(\\n 'syncscan.c',\\n 'toast_compression.c',\\n 'toast_internals.c',\\n+ 'tidstore.c',\\n 'tupconvert.c',\\n 'tupdesc.c',\\n )\\n\\nThese aren't in alphabetical order.\\n\\n\\n\",\n \"msg_date\": \"Wed, 20 Mar 2024 13:48:10 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 20, 2024 at 3:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 14, 2024 at 12:06 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 14, 2024 at 1:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > Locally (not CI), we should try big inputs to make sure we can\\n> > > actually go up to many GB -- it's easier and faster this way than\\n> > > having vacuum give us a large data set.\\n> >\\n> > I'll do these tests.\\n>\\n> I just remembered this -- did any of this kind of testing happen? I\\n> can do it as well.\\n\\nI forgot to report the results. Yes, I did some tests where I inserted\\nmany TIDs to make the tidstore use several GB memory. I did two cases:\\n\\n1. insert 100M blocks of TIDs with an offset of 100.\\n2. insert 10M blocks of TIDs with an offset of 2048.\\n\\nThe tidstore used about 4.8GB and 5.2GB, respectively, and all lookup\\nand iteration results were expected.\\n\\n>\\n> > Thank you. I've incorporated all the comments above. I've attached the\\n> > latest patches, and am going to push them (one by one) after\\n> > self-review again.\\n>\\n> One more cosmetic thing in 0001 that caught my eye:\\n>\\n> diff --git a/src/backend/access/common/Makefile\\n> b/src/backend/access/common/Makefile\\n> index b9aff0ccfd..67b8cc6108 100644\\n> --- a/src/backend/access/common/Makefile\\n> +++ b/src/backend/access/common/Makefile\\n> @@ -27,6 +27,7 @@ OBJS = \\\\\\n> syncscan.o \\\\\\n> toast_compression.o \\\\\\n> toast_internals.o \\\\\\n> + tidstore.o \\\\\\n> tupconvert.o \\\\\\n> tupdesc.o\\n>\\n> diff --git a/src/backend/access/common/meson.build\\n> b/src/backend/access/common/meson.build\\n> index 725041a4ce..a02397855e 100644\\n> --- a/src/backend/access/common/meson.build\\n> +++ b/src/backend/access/common/meson.build\\n> @@ -15,6 +15,7 @@ backend_sources += files(\\n> 'syncscan.c',\\n> 'toast_compression.c',\\n> 'toast_internals.c',\\n> + 'tidstore.c',\\n> 'tupconvert.c',\\n> 'tupdesc.c',\\n> )\\n>\\n> These aren't in alphabetical order.\\n\\nGood catch. I'll fix them before the push.\\n\\nWhile reviewing the codes again, the following two things caught my eyes:\\n\\nin check_set_block_offset() function, we don't take a lock on the\\ntidstore while checking all possible TIDs. I'll add\\nTidStoreLockShare() and TidStoreUnlock() as follows:\\n\\n+ TidStoreLockShare(tidstore);\\n if (TidStoreIsMember(tidstore, &tid))\\n ItemPointerSet(&items.lookup_tids[num_lookup_tids++],\\nblkno, offset);\\n+ TidStoreUnlock(tidstore);\\n\\n---\\nRegarding TidStoreMemoryUsage(), IIUC the caller doesn't need to take\\na lock on the shared tidstore since dsa_get_total_size() (called by\\nRT_MEMORY_USAGE()) does appropriate locking. I think we can mention it\\nin the comment as follows:\\n\\n-/* Return the memory usage of TidStore */\\n+/*\\n+ * Return the memory usage of TidStore.\\n+ *\\n+ * In shared TidStore cases, since shared_ts_memory_usage() does appropriate\\n+ * locking, the caller doesn't need to take a lock.\\n+ */\\n\\nWhat do you think?\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Wed, 20 Mar 2024 22:30:06 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 20, 2024 at 8:30 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> I forgot to report the results. Yes, I did some tests where I inserted\\n> many TIDs to make the tidstore use several GB memory. I did two cases:\\n>\\n> 1. insert 100M blocks of TIDs with an offset of 100.\\n> 2. insert 10M blocks of TIDs with an offset of 2048.\\n>\\n> The tidstore used about 4.8GB and 5.2GB, respectively, and all lookup\\n> and iteration results were expected.\\n\\nThanks for confirming!\\n\\n> While reviewing the codes again, the following two things caught my eyes:\\n>\\n> in check_set_block_offset() function, we don't take a lock on the\\n> tidstore while checking all possible TIDs. I'll add\\n> TidStoreLockShare() and TidStoreUnlock() as follows:\\n>\\n> + TidStoreLockShare(tidstore);\\n> if (TidStoreIsMember(tidstore, &tid))\\n> ItemPointerSet(&items.lookup_tids[num_lookup_tids++],\\n> blkno, offset);\\n> + TidStoreUnlock(tidstore);\\n\\nIn one sense, all locking in the test module is useless since there is\\nonly a single process. On the other hand, it seems good to at least\\nrun what we have written to run it trivially, and serve as an example\\nof usage. We should probably be consistent, and document at the top\\nthat the locks are pro-forma only.\\n\\nIt's both a blessing and a curse that vacuum only has a single writer.\\nIt makes development less of a hassle, but also means that tidstore\\nlocking is done for API-completeness reasons, not (yet) as a practical\\nnecessity. Even tidbitmap.c's hash table currently has a single\\nwriter, and while using tidstore for that is still an engineering\\nchallenge for other reasons, it wouldn't exercise locking\\nmeaningfully, either, at least at first.\\n\\n> Regarding TidStoreMemoryUsage(), IIUC the caller doesn't need to take\\n> a lock on the shared tidstore since dsa_get_total_size() (called by\\n> RT_MEMORY_USAGE()) does appropriate locking. I think we can mention it\\n> in the comment as follows:\\n>\\n> -/* Return the memory usage of TidStore */\\n> +/*\\n> + * Return the memory usage of TidStore.\\n> + *\\n> + * In shared TidStore cases, since shared_ts_memory_usage() does appropriate\\n> + * locking, the caller doesn't need to take a lock.\\n> + */\\n>\\n> What do you think?\\n\\nThat duplicates the underlying comment on the radix tree function that\\nthis calls, so I'm inclined to leave it out. At this level it's\\nprobably best to document when a caller _does_ need to take an action.\\n\\nOne thing I forgot to ask about earlier:\\n\\n+-- Add tids in out of order.\\n\\nAre they (the blocks to be precise) really out of order? The VALUES\\nstatement is ordered, but after inserting it does not output that way.\\nI wondered if this is platform independent, but CI and our dev\\nmachines haven't failed this test, and I haven't looked into what\\ndetermines the order. It's easy enough to hide the blocks if we ever\\nneed to, as we do elsewhere...\\n\\n\\n\",\n \"msg_date\": \"Wed, 20 Mar 2024 21:19:46 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 20, 2024 at 11:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Wed, Mar 20, 2024 at 8:30 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > I forgot to report the results. Yes, I did some tests where I inserted\\n> > many TIDs to make the tidstore use several GB memory. I did two cases:\\n> >\\n> > 1. insert 100M blocks of TIDs with an offset of 100.\\n> > 2. insert 10M blocks of TIDs with an offset of 2048.\\n> >\\n> > The tidstore used about 4.8GB and 5.2GB, respectively, and all lookup\\n> > and iteration results were expected.\\n>\\n> Thanks for confirming!\\n>\\n> > While reviewing the codes again, the following two things caught my eyes:\\n> >\\n> > in check_set_block_offset() function, we don't take a lock on the\\n> > tidstore while checking all possible TIDs. I'll add\\n> > TidStoreLockShare() and TidStoreUnlock() as follows:\\n> >\\n> > + TidStoreLockShare(tidstore);\\n> > if (TidStoreIsMember(tidstore, &tid))\\n> > ItemPointerSet(&items.lookup_tids[num_lookup_tids++],\\n> > blkno, offset);\\n> > + TidStoreUnlock(tidstore);\\n>\\n> In one sense, all locking in the test module is useless since there is\\n> only a single process. On the other hand, it seems good to at least\\n> run what we have written to run it trivially, and serve as an example\\n> of usage. We should probably be consistent, and document at the top\\n> that the locks are pro-forma only.\\n\\nAgreed.\\n\\n>\\n> > Regarding TidStoreMemoryUsage(), IIUC the caller doesn't need to take\\n> > a lock on the shared tidstore since dsa_get_total_size() (called by\\n> > RT_MEMORY_USAGE()) does appropriate locking. I think we can mention it\\n> > in the comment as follows:\\n> >\\n> > -/* Return the memory usage of TidStore */\\n> > +/*\\n> > + * Return the memory usage of TidStore.\\n> > + *\\n> > + * In shared TidStore cases, since shared_ts_memory_usage() does appropriate\\n> > + * locking, the caller doesn't need to take a lock.\\n> > + */\\n> >\\n> > What do you think?\\n>\\n> That duplicates the underlying comment on the radix tree function that\\n> this calls, so I'm inclined to leave it out. At this level it's\\n> probably best to document when a caller _does_ need to take an action.\\n\\nOkay, I didn't change it.\\n\\n>\\n> One thing I forgot to ask about earlier:\\n>\\n> +-- Add tids in out of order.\\n>\\n> Are they (the blocks to be precise) really out of order? The VALUES\\n> statement is ordered, but after inserting it does not output that way.\\n> I wondered if this is platform independent, but CI and our dev\\n> machines haven't failed this test, and I haven't looked into what\\n> determines the order. It's easy enough to hide the blocks if we ever\\n> need to, as we do elsewhere...\\n\\nIt seems not necessary as such a test is already covered by\\ntest_radixtree. I've changed the query to hide the output blocks.\\n\\nI've pushed the tidstore patch after incorporating the above changes.\\nIn addition to that, I've added the following changes before the push:\\n\\n- Added src/test/modules/test_tidstore/.gitignore file.\\n- Removed unnecessary #include from tidstore.c.\\n\\nThe buildfarm has been all-green so far.\\n\\nI've attached the latest vacuum improvement patch.\\n\\nI just remembered that the tidstore cannot still be used for parallel\\nvacuum with minimum maintenance_work_mem. Even when the shared\\ntidstore is empty, its memory usage reports 1056768 bytes, a bit above\\n1MB (1048576 bytes). We need something discussed on another thread[1]\\nin order to make it work.\\n\\nRegards,\\n\\n[1] https://www.postgresql.org/message-id/CAD21AoCVMw6DSmgZY9h%2BxfzKtzJeqWiwxaUD2T-FztVcV-XibQ%40mail.gmail.com\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 21 Mar 2024 11:37:16 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 9:37 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Mar 20, 2024 at 11:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > Are they (the blocks to be precise) really out of order? The VALUES\\n> > statement is ordered, but after inserting it does not output that way.\\n> > I wondered if this is platform independent, but CI and our dev\\n> > machines haven't failed this test, and I haven't looked into what\\n> > determines the order. It's easy enough to hide the blocks if we ever\\n> > need to, as we do elsewhere...\\n>\\n> It seems not necessary as such a test is already covered by\\n> test_radixtree. I've changed the query to hide the output blocks.\\n\\nOkay.\\n\\n> The buildfarm has been all-green so far.\\n\\nGreat!\\n\\n> I've attached the latest vacuum improvement patch.\\n>\\n> I just remembered that the tidstore cannot still be used for parallel\\n> vacuum with minimum maintenance_work_mem. Even when the shared\\n> tidstore is empty, its memory usage reports 1056768 bytes, a bit above\\n> 1MB (1048576 bytes). We need something discussed on another thread[1]\\n> in order to make it work.\\n\\nFor exactly this reason, we used to have a clamp on max_bytes when it\\nwas internal to tidstore, so that it never reported full when first\\ncreated, so I guess that got thrown away when we got rid of the\\ncontrol object in shared memory. Forcing callers to clamp their own\\nlimits seems pretty unfriendly, though.\\n\\nThe proposals in that thread are pretty simple. If those don't move\\nforward soon, a hackish workaround would be to round down the number\\nwe get from dsa_get_total_size to the nearest megabyte. Then\\ncontrolling min/max segment size would be a nice-to-have for PG17, not\\na prerequisite.\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Mar 2024 10:40:05 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 12:40 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 21, 2024 at 9:37 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Wed, Mar 20, 2024 at 11:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > Are they (the blocks to be precise) really out of order? The VALUES\\n> > > statement is ordered, but after inserting it does not output that way.\\n> > > I wondered if this is platform independent, but CI and our dev\\n> > > machines haven't failed this test, and I haven't looked into what\\n> > > determines the order. It's easy enough to hide the blocks if we ever\\n> > > need to, as we do elsewhere...\\n> >\\n> > It seems not necessary as such a test is already covered by\\n> > test_radixtree. I've changed the query to hide the output blocks.\\n>\\n> Okay.\\n>\\n> > The buildfarm has been all-green so far.\\n>\\n> Great!\\n>\\n> > I've attached the latest vacuum improvement patch.\\n> >\\n> > I just remembered that the tidstore cannot still be used for parallel\\n> > vacuum with minimum maintenance_work_mem. Even when the shared\\n> > tidstore is empty, its memory usage reports 1056768 bytes, a bit above\\n> > 1MB (1048576 bytes). We need something discussed on another thread[1]\\n> > in order to make it work.\\n>\\n> For exactly this reason, we used to have a clamp on max_bytes when it\\n> was internal to tidstore, so that it never reported full when first\\n> created, so I guess that got thrown away when we got rid of the\\n> control object in shared memory. Forcing callers to clamp their own\\n> limits seems pretty unfriendly, though.\\n\\nOr we can have a new function for dsa.c to set the initial and max\\nsegment size (or either one) to the existing DSA area so that\\nTidStoreCreate() can specify them at creation. In shared TidStore\\ncases, since all memory required by shared radix tree is allocated in\\nthe passed-in DSA area and the memory usage is the total segment size\\nallocated in the DSA area, the user will have to prepare a DSA area\\nonly for the shared tidstore. So we might be able to expect that the\\nDSA passed-in to TidStoreCreate() is empty and its segment sizes can\\nbe adjustable.\\n\\n>\\n> The proposals in that thread are pretty simple. If those don't move\\n> forward soon, a hackish workaround would be to round down the number\\n> we get from dsa_get_total_size to the nearest megabyte. Then\\n> controlling min/max segment size would be a nice-to-have for PG17, not\\n> a prerequisite.\\n\\nInteresting idea.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Mar 2024 15:10:30 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 3:10 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 21, 2024 at 12:40 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 21, 2024 at 9:37 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Wed, Mar 20, 2024 at 11:19 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > > Are they (the blocks to be precise) really out of order? The VALUES\\n> > > > statement is ordered, but after inserting it does not output that way.\\n> > > > I wondered if this is platform independent, but CI and our dev\\n> > > > machines haven't failed this test, and I haven't looked into what\\n> > > > determines the order. It's easy enough to hide the blocks if we ever\\n> > > > need to, as we do elsewhere...\\n> > >\\n> > > It seems not necessary as such a test is already covered by\\n> > > test_radixtree. I've changed the query to hide the output blocks.\\n> >\\n> > Okay.\\n> >\\n> > > The buildfarm has been all-green so far.\\n> >\\n> > Great!\\n> >\\n> > > I've attached the latest vacuum improvement patch.\\n> > >\\n> > > I just remembered that the tidstore cannot still be used for parallel\\n> > > vacuum with minimum maintenance_work_mem. Even when the shared\\n> > > tidstore is empty, its memory usage reports 1056768 bytes, a bit above\\n> > > 1MB (1048576 bytes). We need something discussed on another thread[1]\\n> > > in order to make it work.\\n> >\\n> > For exactly this reason, we used to have a clamp on max_bytes when it\\n> > was internal to tidstore, so that it never reported full when first\\n> > created, so I guess that got thrown away when we got rid of the\\n> > control object in shared memory. Forcing callers to clamp their own\\n> > limits seems pretty unfriendly, though.\\n>\\n> Or we can have a new function for dsa.c to set the initial and max\\n> segment size (or either one) to the existing DSA area so that\\n> TidStoreCreate() can specify them at creation. In shared TidStore\\n> cases, since all memory required by shared radix tree is allocated in\\n> the passed-in DSA area and the memory usage is the total segment size\\n> allocated in the DSA area, the user will have to prepare a DSA area\\n> only for the shared tidstore. So we might be able to expect that the\\n> DSA passed-in to TidStoreCreate() is empty and its segment sizes can\\n> be adjustable.\\n\\nYet another idea is that TidStore creates its own DSA area in\\nTidStoreCreate(). That is, In TidStoreCreate() we create a DSA area\\n(using dsa_create()) and pass it to RT_CREATE(). Also, we need a new\\nAPI to get the DSA area. The caller (e.g. parallel vacuum) gets the\\ndsa_handle of the DSA and stores it in the shared memory (e.g. in\\nPVShared). TidStoreAttach() will take two arguments: dsa_handle for\\nthe DSA area and dsa_pointer for the shared radix tree. This idea\\nstill requires controlling min/max segment sizes since dsa_create()\\nuses the 1MB as the initial segment size. But the TidStoreCreate()\\nwould be more user friendly.\\n\\nI've attached a PoC patch for discussion.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 21 Mar 2024 16:02:05 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 1:11 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> Or we can have a new function for dsa.c to set the initial and max\\n> segment size (or either one) to the existing DSA area so that\\n> TidStoreCreate() can specify them at creation.\\n\\nI didn't like this very much, because it's splitting an operation\\nacross an API boundary. The caller already has all the information it\\nneeds when it creates the DSA. Straw man proposal: it could do the\\nsame for local memory, then they'd be more similar. But if we made\\nlocal contexts the responsibility of the caller, that would cause\\nduplication between creating and resetting.\\n\\n> In shared TidStore\\n> cases, since all memory required by shared radix tree is allocated in\\n> the passed-in DSA area and the memory usage is the total segment size\\n> allocated in the DSA area\\n\\n...plus apparently some overhead, I just found out today, but that's\\nbeside the point.\\n\\nOn Thu, Mar 21, 2024 at 2:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> Yet another idea is that TidStore creates its own DSA area in\\n> TidStoreCreate(). That is, In TidStoreCreate() we create a DSA area\\n> (using dsa_create()) and pass it to RT_CREATE(). Also, we need a new\\n> API to get the DSA area. The caller (e.g. parallel vacuum) gets the\\n> dsa_handle of the DSA and stores it in the shared memory (e.g. in\\n> PVShared). TidStoreAttach() will take two arguments: dsa_handle for\\n> the DSA area and dsa_pointer for the shared radix tree. This idea\\n> still requires controlling min/max segment sizes since dsa_create()\\n> uses the 1MB as the initial segment size. But the TidStoreCreate()\\n> would be more user friendly.\\n\\nThis seems like an overall simplification, aside from future size\\nconfiguration, so +1 to continue looking into this. If we go this\\nroute, I'd like to avoid a boolean parameter and cleanly separate\\nTidStoreCreateLocal() and TidStoreCreateShared(). Every operation\\nafter that can introspect, but it's a bit awkward to force these cases\\ninto the same function. It always was a little bit, but this change\\nmakes it more so.\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Mar 2024 14:35:08 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 4:35 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 21, 2024 at 1:11 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > Or we can have a new function for dsa.c to set the initial and max\\n> > segment size (or either one) to the existing DSA area so that\\n> > TidStoreCreate() can specify them at creation.\\n>\\n> I didn't like this very much, because it's splitting an operation\\n> across an API boundary. The caller already has all the information it\\n> needs when it creates the DSA. Straw man proposal: it could do the\\n> same for local memory, then they'd be more similar. But if we made\\n> local contexts the responsibility of the caller, that would cause\\n> duplication between creating and resetting.\\n\\nFair point.\\n\\n>\\n> > In shared TidStore\\n> > cases, since all memory required by shared radix tree is allocated in\\n> > the passed-in DSA area and the memory usage is the total segment size\\n> > allocated in the DSA area\\n>\\n> ...plus apparently some overhead, I just found out today, but that's\\n> beside the point.\\n>\\n> On Thu, Mar 21, 2024 at 2:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > Yet another idea is that TidStore creates its own DSA area in\\n> > TidStoreCreate(). That is, In TidStoreCreate() we create a DSA area\\n> > (using dsa_create()) and pass it to RT_CREATE(). Also, we need a new\\n> > API to get the DSA area. The caller (e.g. parallel vacuum) gets the\\n> > dsa_handle of the DSA and stores it in the shared memory (e.g. in\\n> > PVShared). TidStoreAttach() will take two arguments: dsa_handle for\\n> > the DSA area and dsa_pointer for the shared radix tree. This idea\\n> > still requires controlling min/max segment sizes since dsa_create()\\n> > uses the 1MB as the initial segment size. But the TidStoreCreate()\\n> > would be more user friendly.\\n>\\n> This seems like an overall simplification, aside from future size\\n> configuration, so +1 to continue looking into this. If we go this\\n> route, I'd like to avoid a boolean parameter and cleanly separate\\n> TidStoreCreateLocal() and TidStoreCreateShared(). Every operation\\n> after that can introspect, but it's a bit awkward to force these cases\\n> into the same function. It always was a little bit, but this change\\n> makes it more so.\\n\\nI've looked into this idea further. Overall, it looks clean and I\\ndon't see any problem so far in terms of integration with lazy vacuum.\\nI've attached three patches for discussion and tests.\\n\\n- 0001 patch makes lazy vacuum use of tidstore.\\n- 0002 patch makes DSA init/max segment size configurable (borrowed\\nfrom another thread).\\n- 0003 patch makes TidStore create its own DSA area with init/max DSA\\nsegment adjustment (PoC patch).\\n\\nOne thing unclear to me is that this idea will be usable even when we\\nwant to use the tidstore for parallel bitmap scan. Currently, we\\ncreate a shared tidbitmap on a DSA area in ParallelExecutorInfo. This\\nDSA area is used not only for tidbitmap but also for parallel hash\\netc. If the tidstore created its own DSA area, parallel bitmap scan\\nwould have to use the tidstore's DSA in addition to the DSA area in\\nParallelExecutorInfo. I'm not sure if there are some differences\\nbetween these usages in terms of resource manager etc. It seems no\\nproblem but I might be missing something.\\n\\nRegards,\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 21 Mar 2024 18:02:47 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 4:03 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> I've looked into this idea further. Overall, it looks clean and I\\n> don't see any problem so far in terms of integration with lazy vacuum.\\n> I've attached three patches for discussion and tests.\\n\\nSeems okay in the big picture, it's the details we need to be careful of.\\n\\nv77-0001\\n\\n- dead_items = (VacDeadItems *) palloc(vac_max_items_to_alloc_size(max_items));\\n- dead_items->max_items = max_items;\\n- dead_items->num_items = 0;\\n+ vacrel->dead_items = TidStoreCreate(vac_work_mem, NULL, 0);\\n+\\n+ dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));\\n+ dead_items_info->max_bytes = vac_work_mem * 1024L;\\n\\nThis is confusing enough that it looks like a bug:\\n\\n[inside TidStoreCreate()]\\n/* choose the maxBlockSize to be no larger than 1/16 of max_bytes */\\nwhile (16 * maxBlockSize > max_bytes * 1024L)\\nmaxBlockSize >>= 1;\\n\\nThis was copied from CreateWorkExprContext, which operates directly on\\nwork_mem -- if the parameter is actually bytes, we can't \\\"* 1024\\\"\\nhere. If we're passing something measured in kilobytes, the parameter\\nis badly named. Let's use convert once and use bytes everywhere.\\n\\nNote: This was not another pass over the whole vacuum patch, just\\nlooking an the issue at hand.\\nAlso for later: Dilip Kumar reviewed an earlier version.\\n\\nv77-0002:\\n\\n+#define dsa_create(tranch_id) \\\\\\n+ dsa_create_ext(tranch_id, DSA_INITIAL_SEGMENT_SIZE, DSA_MAX_SEGMENT_SIZE)\\n\\nSince these macros are now referring to defaults, maybe their name\\nshould reflect that. Something like DSA_DEFAULT_INIT_SEGMENT_SIZE\\n(*_MAX_*)\\n\\n+/* The minimum size of a DSM segment. */\\n+#define DSA_MIN_SEGMENT_SIZE ((size_t) 1024)\\n\\nThat's a *lot* smaller than it is now. Maybe 256kB? We just want 1MB\\nm_w_m to work correctly.\\n\\nv77-0003:\\n\\n+/* Public APIs to create local or shared TidStore */\\n+\\n+TidStore *\\n+TidStoreCreateLocal(size_t max_bytes)\\n+{\\n+ return tidstore_create_internal(max_bytes, false, 0);\\n+}\\n+\\n+TidStore *\\n+TidStoreCreateShared(size_t max_bytes, int tranche_id)\\n+{\\n+ return tidstore_create_internal(max_bytes, true, tranche_id);\\n+}\\n\\nI don't think these operations have enough in common to justify\\nsharing even an internal implementation. Choosing aset block size is\\ndone for both memory types, but it's pointless to do it for shared\\nmemory, because the local context is then only used for small\\nmetadata.\\n\\n+ /*\\n+ * Choose the DSA initial and max segment sizes to be no longer than\\n+ * 1/16 and 1/8 of max_bytes, respectively.\\n+ */\\n\\nI'm guessing the 1/8 here because the number of segments is limited? I\\nknow these numbers are somewhat arbitrary, but readers will wonder why\\none has 1/8 and the other has 1/16.\\n\\n+ if (dsa_init_size < DSA_MIN_SEGMENT_SIZE)\\n+ dsa_init_size = DSA_MIN_SEGMENT_SIZE;\\n+ if (dsa_max_size < DSA_MAX_SEGMENT_SIZE)\\n+ dsa_max_size = DSA_MAX_SEGMENT_SIZE;\\n\\nThe second clamp seems against the whole point of this patch -- it\\nseems they should all be clamped bigger than the DSA_MIN_SEGMENT_SIZE?\\nDid you try it with 1MB m_w_m?\\n\\n\\n\",\n \"msg_date\": \"Thu, 21 Mar 2024 17:48:35 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 21, 2024 at 7:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 21, 2024 at 4:03 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > I've looked into this idea further. Overall, it looks clean and I\\n> > don't see any problem so far in terms of integration with lazy vacuum.\\n> > I've attached three patches for discussion and tests.\\n>\\n> Seems okay in the big picture, it's the details we need to be careful of.\\n>\\n> v77-0001\\n>\\n> - dead_items = (VacDeadItems *) palloc(vac_max_items_to_alloc_size(max_items));\\n> - dead_items->max_items = max_items;\\n> - dead_items->num_items = 0;\\n> + vacrel->dead_items = TidStoreCreate(vac_work_mem, NULL, 0);\\n> +\\n> + dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));\\n> + dead_items_info->max_bytes = vac_work_mem * 1024L;\\n>\\n> This is confusing enough that it looks like a bug:\\n>\\n> [inside TidStoreCreate()]\\n> /* choose the maxBlockSize to be no larger than 1/16 of max_bytes */\\n> while (16 * maxBlockSize > max_bytes * 1024L)\\n> maxBlockSize >>= 1;\\n>\\n> This was copied from CreateWorkExprContext, which operates directly on\\n> work_mem -- if the parameter is actually bytes, we can't \\\"* 1024\\\"\\n> here. If we're passing something measured in kilobytes, the parameter\\n> is badly named. Let's use convert once and use bytes everywhere.\\n\\nTrue. The attached 0001 patch fixes it.\\n\\n>\\n> v77-0002:\\n>\\n> +#define dsa_create(tranch_id) \\\\\\n> + dsa_create_ext(tranch_id, DSA_INITIAL_SEGMENT_SIZE, DSA_MAX_SEGMENT_SIZE)\\n>\\n> Since these macros are now referring to defaults, maybe their name\\n> should reflect that. Something like DSA_DEFAULT_INIT_SEGMENT_SIZE\\n> (*_MAX_*)\\n\\nIt makes sense to rename DSA_INITIAL_SEGMENT_SIZE , but I think that\\nthe DSA_MAX_SEGMENT_SIZE is the theoretical maximum size, the current\\nname also makes sense to me.\\n\\n>\\n> +/* The minimum size of a DSM segment. */\\n> +#define DSA_MIN_SEGMENT_SIZE ((size_t) 1024)\\n>\\n> That's a *lot* smaller than it is now. Maybe 256kB? We just want 1MB\\n> m_w_m to work correctly.\\n\\nFixed.\\n\\n>\\n> v77-0003:\\n>\\n> +/* Public APIs to create local or shared TidStore */\\n> +\\n> +TidStore *\\n> +TidStoreCreateLocal(size_t max_bytes)\\n> +{\\n> + return tidstore_create_internal(max_bytes, false, 0);\\n> +}\\n> +\\n> +TidStore *\\n> +TidStoreCreateShared(size_t max_bytes, int tranche_id)\\n> +{\\n> + return tidstore_create_internal(max_bytes, true, tranche_id);\\n> +}\\n>\\n> I don't think these operations have enough in common to justify\\n> sharing even an internal implementation. Choosing aset block size is\\n> done for both memory types, but it's pointless to do it for shared\\n> memory, because the local context is then only used for small\\n> metadata.\\n>\\n> + /*\\n> + * Choose the DSA initial and max segment sizes to be no longer than\\n> + * 1/16 and 1/8 of max_bytes, respectively.\\n> + */\\n>\\n> I'm guessing the 1/8 here because the number of segments is limited? I\\n> know these numbers are somewhat arbitrary, but readers will wonder why\\n> one has 1/8 and the other has 1/16.\\n>\\n> + if (dsa_init_size < DSA_MIN_SEGMENT_SIZE)\\n> + dsa_init_size = DSA_MIN_SEGMENT_SIZE;\\n> + if (dsa_max_size < DSA_MAX_SEGMENT_SIZE)\\n> + dsa_max_size = DSA_MAX_SEGMENT_SIZE;\\n>\\n> The second clamp seems against the whole point of this patch -- it\\n> seems they should all be clamped bigger than the DSA_MIN_SEGMENT_SIZE?\\n> Did you try it with 1MB m_w_m?\\n\\nI've incorporated the above comments and test results look good to me.\\n\\nI've attached the several patches:\\n\\n- 0002 is a minor fix for tidstore I found.\\n- 0005 changes the create APIs of tidstore.\\n- 0006 update the vacuum improvement patch to use the new\\nTidStoreCreateLocal/Shared() APIs.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Fri, 22 Mar 2024 14:19:44 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"John Naylor <johncnaylorls@gmail.com> writes:\\n> Done. I pushed this with a few last-minute cosmetic adjustments. This\\n> has been a very long time coming, but we're finally in the home\\n> stretch!\\n\\nI'm not sure why it took a couple weeks for Coverity to notice\\nee1b30f12, but it saw it today, and it's not happy:\\n\\n/srv/coverity/git/pgsql-git/postgresql/src/include/lib/radixtree.h: 1621 in local_ts_extend_down()\\n1615 \\t\\tnode = child;\\n1616 \\t\\tshift -= RT_SPAN;\\n1617 \\t}\\n1618 \\n1619 \\t/* Reserve slot for the value. */\\n1620 \\tn4 = (RT_NODE_4 *) node.local;\\n>>> CID 1594658: Integer handling issues (BAD_SHIFT)\\n>>> In expression \\\"key >> shift\\\", shifting by a negative amount has undefined behavior. The shift amount, \\\"shift\\\", is as little as -7.\\n1621 \\tn4->chunks[0] = RT_GET_KEY_CHUNK(key, shift);\\n1622 \\tn4->base.count = 1;\\n1623 \\n1624 \\treturn &n4->children[0];\\n1625 }\\n1626 \\n\\nI think the point here is that if you start with an arbitrary\\nnon-negative shift value, the preceding loop may in fact decrement it\\ndown to something less than zero before exiting, in which case we\\nwould indeed have trouble. I suspect that the code is making\\nundocumented assumptions about the possible initial values of shift.\\nMaybe some Asserts would be good? Also, if we're effectively assuming\\nthat shift must be exactly zero here, why not let the compiler\\nhard-code that?\\n\\n- \\tn4->chunks[0] = RT_GET_KEY_CHUNK(key, shift);\\n+ \\tn4->chunks[0] = RT_GET_KEY_CHUNK(key, 0);\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Mar 2024 12:53:36 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 25, 2024 at 1:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>\\n> John Naylor <johncnaylorls@gmail.com> writes:\\n> > Done. I pushed this with a few last-minute cosmetic adjustments. This\\n> > has been a very long time coming, but we're finally in the home\\n> > stretch!\\n\\nThank you for the report.\\n\\n>\\n> I'm not sure why it took a couple weeks for Coverity to notice\\n> ee1b30f12, but it saw it today, and it's not happy:\\n\\nHmm, I've also done Coverity Scan in development but I wasn't able to\\nsee this one for some reason...\\n\\n>\\n> /srv/coverity/git/pgsql-git/postgresql/src/include/lib/radixtree.h: 1621 in local_ts_extend_down()\\n> 1615 node = child;\\n> 1616 shift -= RT_SPAN;\\n> 1617 }\\n> 1618\\n> 1619 /* Reserve slot for the value. */\\n> 1620 n4 = (RT_NODE_4 *) node.local;\\n> >>> CID 1594658: Integer handling issues (BAD_SHIFT)\\n> >>> In expression \\\"key >> shift\\\", shifting by a negative amount has undefined behavior. The shift amount, \\\"shift\\\", is as little as -7.\\n> 1621 n4->chunks[0] = RT_GET_KEY_CHUNK(key, shift);\\n> 1622 n4->base.count = 1;\\n> 1623\\n> 1624 return &n4->children[0];\\n> 1625 }\\n> 1626\\n>\\n> I think the point here is that if you start with an arbitrary\\n> non-negative shift value, the preceding loop may in fact decrement it\\n> down to something less than zero before exiting, in which case we\\n> would indeed have trouble. I suspect that the code is making\\n> undocumented assumptions about the possible initial values of shift.\\n> Maybe some Asserts would be good? Also, if we're effectively assuming\\n> that shift must be exactly zero here, why not let the compiler\\n> hard-code that?\\n>\\n> - n4->chunks[0] = RT_GET_KEY_CHUNK(key, shift);\\n> + n4->chunks[0] = RT_GET_KEY_CHUNK(key, 0);\\n\\nSounds like a good solution. I've attached the patch for that.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 25 Mar 2024 10:02:18 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Masahiko Sawada <sawada.mshk@gmail.com> writes:\\n> On Mon, Mar 25, 2024 at 1:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>> I think the point here is that if you start with an arbitrary\\n>> non-negative shift value, the preceding loop may in fact decrement it\\n>> down to something less than zero before exiting, in which case we\\n>> would indeed have trouble. I suspect that the code is making\\n>> undocumented assumptions about the possible initial values of shift.\\n>> Maybe some Asserts would be good? Also, if we're effectively assuming\\n>> that shift must be exactly zero here, why not let the compiler\\n>> hard-code that?\\n\\n> Sounds like a good solution. I've attached the patch for that.\\n\\nPersonally I'd put the Assert immediately after the loop, because\\nit's not related to the \\\"Reserve slot for the value\\\" comment.\\nSeems reasonable otherwise.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Mar 2024 21:13:24 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 25, 2024 at 8:02 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Mar 25, 2024 at 1:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> >\\n> > I'm not sure why it took a couple weeks for Coverity to notice\\n> > ee1b30f12, but it saw it today, and it's not happy:\\n>\\n> Hmm, I've also done Coverity Scan in development but I wasn't able to\\n> see this one for some reason...\\n\\nHmm, before 30e144287 this code only ran in a test module, is it\\npossible Coverity would not find it there?\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Mar 2024 08:14:06 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"John Naylor <johncnaylorls@gmail.com> writes:\\n> Hmm, before 30e144287 this code only ran in a test module, is it\\n> possible Coverity would not find it there?\\n\\nThat could indeed explain why Coverity didn't see it. I'm not\\nsure how our community run is set up, but it may not build the\\ntest modules.\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Sun, 24 Mar 2024 21:27:18 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 25, 2024 at 10:13 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n>\\n> Masahiko Sawada <sawada.mshk@gmail.com> writes:\\n> > On Mon, Mar 25, 2024 at 1:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:\\n> >> I think the point here is that if you start with an arbitrary\\n> >> non-negative shift value, the preceding loop may in fact decrement it\\n> >> down to something less than zero before exiting, in which case we\\n> >> would indeed have trouble. I suspect that the code is making\\n> >> undocumented assumptions about the possible initial values of shift.\\n> >> Maybe some Asserts would be good? Also, if we're effectively assuming\\n> >> that shift must be exactly zero here, why not let the compiler\\n> >> hard-code that?\\n>\\n> > Sounds like a good solution. I've attached the patch for that.\\n>\\n> Personally I'd put the Assert immediately after the loop, because\\n> it's not related to the \\\"Reserve slot for the value\\\" comment.\\n> Seems reasonable otherwise.\\n>\\n\\nThanks. Pushed the fix after moving the Assert.\\n\\n\\nRegards,\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Mar 2024 12:13:19 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 22, 2024 at 12:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Mar 21, 2024 at 7:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > v77-0001\\n> >\\n> > - dead_items = (VacDeadItems *) palloc(vac_max_items_to_alloc_size(max_items));\\n> > - dead_items->max_items = max_items;\\n> > - dead_items->num_items = 0;\\n> > + vacrel->dead_items = TidStoreCreate(vac_work_mem, NULL, 0);\\n> > +\\n> > + dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));\\n> > + dead_items_info->max_bytes = vac_work_mem * 1024L;\\n> >\\n> > This is confusing enough that it looks like a bug:\\n> >\\n> > [inside TidStoreCreate()]\\n> > /* choose the maxBlockSize to be no larger than 1/16 of max_bytes */\\n> > while (16 * maxBlockSize > max_bytes * 1024L)\\n> > maxBlockSize >>= 1;\\n> >\\n> > This was copied from CreateWorkExprContext, which operates directly on\\n> > work_mem -- if the parameter is actually bytes, we can't \\\"* 1024\\\"\\n> > here. If we're passing something measured in kilobytes, the parameter\\n> > is badly named. Let's use convert once and use bytes everywhere.\\n>\\n> True. The attached 0001 patch fixes it.\\n\\nv78-0001 and 02 are fine, but for 0003 there is a consequence that I\\ndidn't see mentioned: vac_work_mem now refers to bytes, where before\\nit referred to kilobytes. It seems pretty confusing to use a different\\nconvention from elsewhere, especially if it has the same name but\\ndifferent meaning across versions. Worse, this change is buried inside\\na moving-stuff-around diff, making it hard to see. Maybe \\\"convert only\\nonce\\\" is still possible, but I was actually thinking of\\n\\n+ dead_items_info->max_bytes = vac_work_mem * 1024L;\\n+ vacrel->dead_items = TidStoreCreate(dead_items_info->max_bytes, NULL, 0);\\n\\nThat way it's pretty obvious that it's correct. That may require a bit\\nof duplication and moving around for shmem, but there is some of that\\nalready.\\n\\nMore on 0003:\\n\\n- * The major space usage for vacuuming is storage for the array of dead TIDs\\n+ * The major space usage for vacuuming is TidStore, a storage for dead TIDs\\n\\n+ * autovacuum_work_mem) memory space to keep track of dead TIDs. If the\\n+ * TidStore is full, we must call lazy_vacuum to vacuum indexes (and to vacuum\\n\\nI wonder if the comments here should refer to it using a more natural\\nspelling, like \\\"TID store\\\".\\n\\n- * items in the dead_items array for later vacuuming, count live and\\n+ * items in the dead_items for later vacuuming, count live and\\n\\nMaybe \\\"the dead_items area\\\", or \\\"the dead_items store\\\" or \\\"in dead_items\\\"?\\n\\n- * remaining LP_DEAD line pointers on the page in the dead_items\\n- * array. These dead items include those pruned by lazy_scan_prune()\\n- * as well we line pointers previously marked LP_DEAD.\\n+ * remaining LP_DEAD line pointers on the page in the dead_items.\\n+ * These dead items include those pruned by lazy_scan_prune() as well\\n+ * we line pointers previously marked LP_DEAD.\\n\\nHere maybe \\\"into dead_items\\\".\\n\\nAlso, \\\"we line pointers\\\" seems to be a pre-existing typo.\\n\\n- (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed %lld dead item identifiers in %u pages\\\",\\n- vacrel->relname, (long long) index, vacuumed_pages)));\\n+ (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed \\\" INT64_FORMAT \\\"dead item identifiers\\nin %u pages\\\",\\n+ vacrel->relname, vacrel->dead_items_info->num_items, vacuumed_pages)));\\n\\nThis is a translated message, so let's keep the message the same.\\n\\n/*\\n * Allocate dead_items (either using palloc, or in dynamic shared memory).\\n * Sets dead_items in vacrel for caller.\\n *\\n * Also handles parallel initialization as part of allocating dead_items in\\n * DSM when required.\\n */\\nstatic void\\ndead_items_alloc(LVRelState *vacrel, int nworkers)\\n\\nThis comment didn't change at all. It's not wrong, but let's consider\\nupdating the specifics.\\n\\nv78-0004:\\n\\n> > +#define dsa_create(tranch_id) \\\\\\n> > + dsa_create_ext(tranch_id, DSA_INITIAL_SEGMENT_SIZE, DSA_MAX_SEGMENT_SIZE)\\n> >\\n> > Since these macros are now referring to defaults, maybe their name\\n> > should reflect that. Something like DSA_DEFAULT_INIT_SEGMENT_SIZE\\n> > (*_MAX_*)\\n>\\n> It makes sense to rename DSA_INITIAL_SEGMENT_SIZE , but I think that\\n> the DSA_MAX_SEGMENT_SIZE is the theoretical maximum size, the current\\n> name also makes sense to me.\\n\\nRight, that makes sense.\\n\\nv78-0005:\\n\\n\\\"Although commit XXX\\nallowed specifying the initial and maximum DSA segment sizes, callers\\nstill needed to clamp their own limits, which was not consistent and\\nuser-friendly.\\\"\\n\\nPerhaps s/still needed/would have needed/ ..., since we're preventing\\nthat necessity.\\n\\n> > Did you try it with 1MB m_w_m?\\n>\\n> I've incorporated the above comments and test results look good to me.\\n\\nCould you be more specific about what the test was?\\nDoes it work with 1MB m_w_m?\\n\\n+ /*\\n+ * Choose the initial and maximum DSA segment sizes to be no longer\\n+ * than 1/16 and 1/8 of max_bytes, respectively. If the initial\\n+ * segment size is low, we end up having many segments, which risks\\n+ * exceeding the total number of segments the platform can have.\\n\\nThe second sentence is technically correct, but I'm not sure how it\\nrelates to the code that follows.\\n\\n+ while (16 * dsa_init_size > max_bytes)\\n+ dsa_init_size >>= 1;\\n+ while (8 * dsa_max_size > max_bytes)\\n+ dsa_max_size >>= 1;\\n\\nI'm not sure we need a separate loop for \\\"dsa_init_size\\\". Can we just have :\\n\\nwhile (8 * dsa_max_size > max_bytes)\\n dsa_max_size >>= 1;\\n\\nif (dsa_max_size < DSA_MIN_SEGMENT_SIZE)\\n dsa_max_size = DSA_MIN_SEGMENT_SIZE;\\n\\nif (dsa_init_size > dsa_max_size)\\n dsa_init_size = dsa_max_size;\\n\\n@@ -113,13 +113,10 @@ static void\\ntidstore_iter_extract_tids(TidStoreIter *iter, BlockNumber blkno,\\n * CurrentMemoryContext at the time of this call. The TID storage, backed\\n * by a radix tree, will live in its child memory context, rt_context. The\\n * TidStore will be limited to (approximately) max_bytes total memory\\n- * consumption. If the 'area' is non-NULL, the radix tree is created in the\\n- * DSA area.\\n- *\\n- * The returned object is allocated in backend-local memory.\\n+ * consumption.\\n\\nThe existing comment slipped past my radar, but max_bytes is not a\\nlimit, it's a hint. Come to think of it, it never was a limit in the\\nnormal sense, but in earlier patches it was the criteria for reporting\\n\\\"I'm full\\\" when asked.\\n\\n void\\n TidStoreDestroy(TidStore *ts)\\n {\\n- /* Destroy underlying radix tree */\\n if (TidStoreIsShared(ts))\\n+ {\\n+ /* Destroy underlying radix tree */\\n shared_ts_free(ts->tree.shared);\\n+\\n+ dsa_detach(ts->area);\\n+ }\\n else\\n local_ts_free(ts->tree.local);\\n\\nIt's still destroyed in the local case, so not sure why this comment was moved?\\n\\nv78-0006:\\n\\n-#define PARALLEL_VACUUM_KEY_DEAD_ITEMS 2\\n+/* 2 was PARALLEL_VACUUM_KEY_DEAD_ITEMS */\\n\\nI don't see any use in core outside this module -- maybe it's possible\\nto renumber these?\\n\\n\\n\",\n \"msg_date\": \"Mon, 25 Mar 2024 13:25:17 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 25, 2024 at 3:25 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Fri, Mar 22, 2024 at 12:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Thu, Mar 21, 2024 at 7:48 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > v77-0001\\n> > >\\n> > > - dead_items = (VacDeadItems *) palloc(vac_max_items_to_alloc_size(max_items));\\n> > > - dead_items->max_items = max_items;\\n> > > - dead_items->num_items = 0;\\n> > > + vacrel->dead_items = TidStoreCreate(vac_work_mem, NULL, 0);\\n> > > +\\n> > > + dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));\\n> > > + dead_items_info->max_bytes = vac_work_mem * 1024L;\\n> > >\\n> > > This is confusing enough that it looks like a bug:\\n> > >\\n> > > [inside TidStoreCreate()]\\n> > > /* choose the maxBlockSize to be no larger than 1/16 of max_bytes */\\n> > > while (16 * maxBlockSize > max_bytes * 1024L)\\n> > > maxBlockSize >>= 1;\\n> > >\\n> > > This was copied from CreateWorkExprContext, which operates directly on\\n> > > work_mem -- if the parameter is actually bytes, we can't \\\"* 1024\\\"\\n> > > here. If we're passing something measured in kilobytes, the parameter\\n> > > is badly named. Let's use convert once and use bytes everywhere.\\n> >\\n> > True. The attached 0001 patch fixes it.\\n>\\n> v78-0001 and 02 are fine, but for 0003 there is a consequence that I\\n> didn't see mentioned:\\n\\nI think that the fix done in 0001 patch can be merged into 0003 patch.\\n\\n> vac_work_mem now refers to bytes, where before\\n> it referred to kilobytes. It seems pretty confusing to use a different\\n> convention from elsewhere, especially if it has the same name but\\n> different meaning across versions. Worse, this change is buried inside\\n> a moving-stuff-around diff, making it hard to see. Maybe \\\"convert only\\n> once\\\" is still possible, but I was actually thinking of\\n>\\n> + dead_items_info->max_bytes = vac_work_mem * 1024L;\\n> + vacrel->dead_items = TidStoreCreate(dead_items_info->max_bytes, NULL, 0);\\n>\\n> That way it's pretty obvious that it's correct. That may require a bit\\n> of duplication and moving around for shmem, but there is some of that\\n> already.\\n\\nAgreed.\\n\\n>\\n> More on 0003:\\n>\\n> - * The major space usage for vacuuming is storage for the array of dead TIDs\\n> + * The major space usage for vacuuming is TidStore, a storage for dead TIDs\\n>\\n> + * autovacuum_work_mem) memory space to keep track of dead TIDs. If the\\n> + * TidStore is full, we must call lazy_vacuum to vacuum indexes (and to vacuum\\n>\\n> I wonder if the comments here should refer to it using a more natural\\n> spelling, like \\\"TID store\\\".\\n>\\n> - * items in the dead_items array for later vacuuming, count live and\\n> + * items in the dead_items for later vacuuming, count live and\\n>\\n> Maybe \\\"the dead_items area\\\", or \\\"the dead_items store\\\" or \\\"in dead_items\\\"?\\n>\\n> - * remaining LP_DEAD line pointers on the page in the dead_items\\n> - * array. These dead items include those pruned by lazy_scan_prune()\\n> - * as well we line pointers previously marked LP_DEAD.\\n> + * remaining LP_DEAD line pointers on the page in the dead_items.\\n> + * These dead items include those pruned by lazy_scan_prune() as well\\n> + * we line pointers previously marked LP_DEAD.\\n>\\n> Here maybe \\\"into dead_items\\\".\\n>\\n> Also, \\\"we line pointers\\\" seems to be a pre-existing typo.\\n>\\n> - (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed %lld dead item identifiers in %u pages\\\",\\n> - vacrel->relname, (long long) index, vacuumed_pages)));\\n> + (errmsg(\\\"table \\\\\\\"%s\\\\\\\": removed \\\" INT64_FORMAT \\\"dead item identifiers\\n> in %u pages\\\",\\n> + vacrel->relname, vacrel->dead_items_info->num_items, vacuumed_pages)));\\n>\\n> This is a translated message, so let's keep the message the same.\\n>\\n> /*\\n> * Allocate dead_items (either using palloc, or in dynamic shared memory).\\n> * Sets dead_items in vacrel for caller.\\n> *\\n> * Also handles parallel initialization as part of allocating dead_items in\\n> * DSM when required.\\n> */\\n> static void\\n> dead_items_alloc(LVRelState *vacrel, int nworkers)\\n>\\n> This comment didn't change at all. It's not wrong, but let's consider\\n> updating the specifics.\\n\\nFixed above comments.\\n\\n> v78-0005:\\n>\\n> \\\"Although commit XXX\\n> allowed specifying the initial and maximum DSA segment sizes, callers\\n> still needed to clamp their own limits, which was not consistent and\\n> user-friendly.\\\"\\n>\\n> Perhaps s/still needed/would have needed/ ..., since we're preventing\\n> that necessity.\\n>\\n> > > Did you try it with 1MB m_w_m?\\n> >\\n> > I've incorporated the above comments and test results look good to me.\\n>\\n> Could you be more specific about what the test was?\\n> Does it work with 1MB m_w_m?\\n\\nIf m_w_m is 1MB, both the initial and maximum segment sizes are 256kB.\\n\\nFYI other test cases I tested were:\\n\\n* m_w_m = 2199023254528 (maximum value)\\ninitial: 1MB\\nmax: 128GB\\n\\n* m_w_m = 64MB (default)\\ninitial: 1MB\\nmax: 8MB\\n\\n>\\n> + /*\\n> + * Choose the initial and maximum DSA segment sizes to be no longer\\n> + * than 1/16 and 1/8 of max_bytes, respectively. If the initial\\n> + * segment size is low, we end up having many segments, which risks\\n> + * exceeding the total number of segments the platform can have.\\n>\\n> The second sentence is technically correct, but I'm not sure how it\\n> relates to the code that follows.\\n>\\n> + while (16 * dsa_init_size > max_bytes)\\n> + dsa_init_size >>= 1;\\n> + while (8 * dsa_max_size > max_bytes)\\n> + dsa_max_size >>= 1;\\n>\\n> I'm not sure we need a separate loop for \\\"dsa_init_size\\\". Can we just have :\\n>\\n> while (8 * dsa_max_size > max_bytes)\\n> dsa_max_size >>= 1;\\n>\\n> if (dsa_max_size < DSA_MIN_SEGMENT_SIZE)\\n> dsa_max_size = DSA_MIN_SEGMENT_SIZE;\\n>\\n> if (dsa_init_size > dsa_max_size)\\n> dsa_init_size = dsa_max_size;\\n\\nAgreed.\\n\\n>\\n> @@ -113,13 +113,10 @@ static void\\n> tidstore_iter_extract_tids(TidStoreIter *iter, BlockNumber blkno,\\n> * CurrentMemoryContext at the time of this call. The TID storage, backed\\n> * by a radix tree, will live in its child memory context, rt_context. The\\n> * TidStore will be limited to (approximately) max_bytes total memory\\n> - * consumption. If the 'area' is non-NULL, the radix tree is created in the\\n> - * DSA area.\\n> - *\\n> - * The returned object is allocated in backend-local memory.\\n> + * consumption.\\n>\\n> The existing comment slipped past my radar, but max_bytes is not a\\n> limit, it's a hint. Come to think of it, it never was a limit in the\\n> normal sense, but in earlier patches it was the criteria for reporting\\n> \\\"I'm full\\\" when asked.\\n\\nUpdated the comment.\\n\\n>\\n> void\\n> TidStoreDestroy(TidStore *ts)\\n> {\\n> - /* Destroy underlying radix tree */\\n> if (TidStoreIsShared(ts))\\n> + {\\n> + /* Destroy underlying radix tree */\\n> shared_ts_free(ts->tree.shared);\\n> +\\n> + dsa_detach(ts->area);\\n> + }\\n> else\\n> local_ts_free(ts->tree.local);\\n>\\n> It's still destroyed in the local case, so not sure why this comment was moved?\\n>\\n> v78-0006:\\n>\\n> -#define PARALLEL_VACUUM_KEY_DEAD_ITEMS 2\\n> +/* 2 was PARALLEL_VACUUM_KEY_DEAD_ITEMS */\\n>\\n> I don't see any use in core outside this module -- maybe it's possible\\n> to renumber these?\\n\\nFixed the above points.\\n\\nI've attached the latest patches. The 0004 and 0006 patches are\\nupdates from the previous version.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 25 Mar 2024 22:06:46 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Mar 25, 2024 at 8:07 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Mar 25, 2024 at 3:25 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Fri, Mar 22, 2024 at 12:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n\\n> > - * remaining LP_DEAD line pointers on the page in the dead_items\\n> > - * array. These dead items include those pruned by lazy_scan_prune()\\n> > - * as well we line pointers previously marked LP_DEAD.\\n> > + * remaining LP_DEAD line pointers on the page in the dead_items.\\n> > + * These dead items include those pruned by lazy_scan_prune() as well\\n> > + * we line pointers previously marked LP_DEAD.\\n> >\\n> > Here maybe \\\"into dead_items\\\".\\n\\n- * remaining LP_DEAD line pointers on the page in the dead_items.\\n+ * remaining LP_DEAD line pointers on the page into the dead_items.\\n\\nLet me explain. It used to be \\\"in the dead_items array.\\\" It is not an\\narray anymore, so it was changed to \\\"in the dead_items\\\". dead_items is\\na variable name, and names don't take \\\"the\\\". \\\"into dead_items\\\" seems\\nmost natural to me, but there are other possible phrasings.\\n\\n> > > > Did you try it with 1MB m_w_m?\\n> > >\\n> > > I've incorporated the above comments and test results look good to me.\\n> >\\n> > Could you be more specific about what the test was?\\n> > Does it work with 1MB m_w_m?\\n>\\n> If m_w_m is 1MB, both the initial and maximum segment sizes are 256kB.\\n>\\n> FYI other test cases I tested were:\\n>\\n> * m_w_m = 2199023254528 (maximum value)\\n> initial: 1MB\\n> max: 128GB\\n>\\n> * m_w_m = 64MB (default)\\n> initial: 1MB\\n> max: 8MB\\n\\nIf the test was a vacuum, how big a table was needed to hit 128GB?\\n\\n> > The existing comment slipped past my radar, but max_bytes is not a\\n> > limit, it's a hint. Come to think of it, it never was a limit in the\\n> > normal sense, but in earlier patches it was the criteria for reporting\\n> > \\\"I'm full\\\" when asked.\\n>\\n> Updated the comment.\\n\\n+ * max_bytes is not a limit; it's used to choose the memory block sizes of\\n+ * a memory context for TID storage in order for the total memory consumption\\n+ * not to be overshot a lot. The caller can use the max_bytes as the criteria\\n+ * for reporting whether it's full or not.\\n\\nThis is good information. I suggest this edit:\\n\\n\\\"max_bytes\\\" is not an internally-enforced limit; it is used only as a\\nhint to cap the memory block size of the memory context for TID\\nstorage. This reduces space wastage due to over-allocation. If the\\ncaller wants to monitor memory usage, it must compare its limit with\\nthe value reported by TidStoreMemoryUsage().\\n\\nOther comments:\\n\\nv79-0002 looks good to me.\\n\\nv79-0003:\\n\\n\\\"With this commit, when creating a shared TidStore, a dedicated DSA\\narea is created for TID storage instead of using the provided DSA\\narea.\\\"\\n\\nThis is very subtle, but \\\"the provided...\\\" implies there still is one.\\n-> \\\"a provided...\\\"\\n\\n+ * Similar to TidStoreCreateLocal() but create a shared TidStore on a\\n+ * DSA area. The TID storage will live in the DSA area, and a memory\\n+ * context rt_context will have only meta data of the radix tree.\\n\\n-> \\\"the memory context\\\"\\n\\nI think you can go ahead and commit 0002 and 0003/4.\\n\\nv79-0005:\\n\\n- bypass = (vacrel->lpdead_item_pages < threshold &&\\n- vacrel->lpdead_items < MAXDEADITEMS(32L * 1024L * 1024L));\\n+ bypass = (vacrel->lpdead_item_pages < threshold) &&\\n+ TidStoreMemoryUsage(vacrel->dead_items) < (32L * 1024L * 1024L);\\n\\nThe parentheses look strange, and the first line shouldn't change\\nwithout a good reason.\\n\\n- /* Set dead_items space */\\n- dead_items = (VacDeadItems *) shm_toc_lookup(toc,\\n- PARALLEL_VACUUM_KEY_DEAD_ITEMS,\\n- false);\\n+ /* Set dead items */\\n+ dead_items = TidStoreAttach(shared->dead_items_dsa_handle,\\n+ shared->dead_items_handle);\\n\\nI feel ambivalent about this comment change. The original is not very\\ndescriptive to begin with. If we need to change at all, maybe \\\"find\\ndead_items in shared memory\\\"?\\n\\nv79-0005: As I said earlier, Dilip Kumar reviewed an earlier version.\\n\\nv79-0006:\\n\\nvac_work_mem should also go back to being an int.\\n\\n\\n\",\n \"msg_date\": \"Wed, 27 Mar 2024 07:24:50 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 27, 2024 at 9:25 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Mon, Mar 25, 2024 at 8:07 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 25, 2024 at 3:25 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > >\\n> > > On Fri, Mar 22, 2024 at 12:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > > - * remaining LP_DEAD line pointers on the page in the dead_items\\n> > > - * array. These dead items include those pruned by lazy_scan_prune()\\n> > > - * as well we line pointers previously marked LP_DEAD.\\n> > > + * remaining LP_DEAD line pointers on the page in the dead_items.\\n> > > + * These dead items include those pruned by lazy_scan_prune() as well\\n> > > + * we line pointers previously marked LP_DEAD.\\n> > >\\n> > > Here maybe \\\"into dead_items\\\".\\n>\\n> - * remaining LP_DEAD line pointers on the page in the dead_items.\\n> + * remaining LP_DEAD line pointers on the page into the dead_items.\\n>\\n> Let me explain. It used to be \\\"in the dead_items array.\\\" It is not an\\n> array anymore, so it was changed to \\\"in the dead_items\\\". dead_items is\\n> a variable name, and names don't take \\\"the\\\". \\\"into dead_items\\\" seems\\n> most natural to me, but there are other possible phrasings.\\n\\nThanks for the explanation. I was distracted. Fixed in the latest patch.\\n\\n>\\n> > > > > Did you try it with 1MB m_w_m?\\n> > > >\\n> > > > I've incorporated the above comments and test results look good to me.\\n> > >\\n> > > Could you be more specific about what the test was?\\n> > > Does it work with 1MB m_w_m?\\n> >\\n> > If m_w_m is 1MB, both the initial and maximum segment sizes are 256kB.\\n> >\\n> > FYI other test cases I tested were:\\n> >\\n> > * m_w_m = 2199023254528 (maximum value)\\n> > initial: 1MB\\n> > max: 128GB\\n> >\\n> > * m_w_m = 64MB (default)\\n> > initial: 1MB\\n> > max: 8MB\\n>\\n> If the test was a vacuum, how big a table was needed to hit 128GB?\\n\\nI just checked how TIdStoreCreateLocal() calculated the initial and\\nmax segment sizes while changing m_w_m, so didn't check how big\\nsegments are actually allocated in the maximum value test case.\\n\\n>\\n> > > The existing comment slipped past my radar, but max_bytes is not a\\n> > > limit, it's a hint. Come to think of it, it never was a limit in the\\n> > > normal sense, but in earlier patches it was the criteria for reporting\\n> > > \\\"I'm full\\\" when asked.\\n> >\\n> > Updated the comment.\\n>\\n> + * max_bytes is not a limit; it's used to choose the memory block sizes of\\n> + * a memory context for TID storage in order for the total memory consumption\\n> + * not to be overshot a lot. The caller can use the max_bytes as the criteria\\n> + * for reporting whether it's full or not.\\n>\\n> This is good information. I suggest this edit:\\n>\\n> \\\"max_bytes\\\" is not an internally-enforced limit; it is used only as a\\n> hint to cap the memory block size of the memory context for TID\\n> storage. This reduces space wastage due to over-allocation. If the\\n> caller wants to monitor memory usage, it must compare its limit with\\n> the value reported by TidStoreMemoryUsage().\\n>\\n> Other comments:\\n\\nThanks for the suggestion!\\n\\n>\\n> v79-0002 looks good to me.\\n>\\n> v79-0003:\\n>\\n> \\\"With this commit, when creating a shared TidStore, a dedicated DSA\\n> area is created for TID storage instead of using the provided DSA\\n> area.\\\"\\n>\\n> This is very subtle, but \\\"the provided...\\\" implies there still is one.\\n> -> \\\"a provided...\\\"\\n>\\n> + * Similar to TidStoreCreateLocal() but create a shared TidStore on a\\n> + * DSA area. The TID storage will live in the DSA area, and a memory\\n> + * context rt_context will have only meta data of the radix tree.\\n>\\n> -> \\\"the memory context\\\"\\n\\nFixed in the latest patch.\\n\\n>\\n> I think you can go ahead and commit 0002 and 0003/4.\\n\\nI've pushed the 0002 (dsa init and max segment size) patch, and will\\npush the attached 0001 patch next.\\n\\n>\\n> v79-0005:\\n>\\n> - bypass = (vacrel->lpdead_item_pages < threshold &&\\n> - vacrel->lpdead_items < MAXDEADITEMS(32L * 1024L * 1024L));\\n> + bypass = (vacrel->lpdead_item_pages < threshold) &&\\n> + TidStoreMemoryUsage(vacrel->dead_items) < (32L * 1024L * 1024L);\\n>\\n> The parentheses look strange, and the first line shouldn't change\\n> without a good reason.\\n\\nFixed.\\n\\n>\\n> - /* Set dead_items space */\\n> - dead_items = (VacDeadItems *) shm_toc_lookup(toc,\\n> - PARALLEL_VACUUM_KEY_DEAD_ITEMS,\\n> - false);\\n> + /* Set dead items */\\n> + dead_items = TidStoreAttach(shared->dead_items_dsa_handle,\\n> + shared->dead_items_handle);\\n>\\n> I feel ambivalent about this comment change. The original is not very\\n> descriptive to begin with. If we need to change at all, maybe \\\"find\\n> dead_items in shared memory\\\"?\\n\\nAgreed.\\n\\n>\\n> v79-0005: As I said earlier, Dilip Kumar reviewed an earlier version.\\n>\\n> v79-0006:\\n>\\n> vac_work_mem should also go back to being an int.\\n\\nFixed.\\n\\nI've attached the latest patches.\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 27 Mar 2024 17:43:37 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, Mar 27, 2024 at 5:43 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Wed, Mar 27, 2024 at 9:25 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Mon, Mar 25, 2024 at 8:07 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > On Mon, Mar 25, 2024 at 3:25 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > > >\\n> > > > On Fri, Mar 22, 2024 at 12:20 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > > - * remaining LP_DEAD line pointers on the page in the dead_items\\n> > > > - * array. These dead items include those pruned by lazy_scan_prune()\\n> > > > - * as well we line pointers previously marked LP_DEAD.\\n> > > > + * remaining LP_DEAD line pointers on the page in the dead_items.\\n> > > > + * These dead items include those pruned by lazy_scan_prune() as well\\n> > > > + * we line pointers previously marked LP_DEAD.\\n> > > >\\n> > > > Here maybe \\\"into dead_items\\\".\\n> >\\n> > - * remaining LP_DEAD line pointers on the page in the dead_items.\\n> > + * remaining LP_DEAD line pointers on the page into the dead_items.\\n> >\\n> > Let me explain. It used to be \\\"in the dead_items array.\\\" It is not an\\n> > array anymore, so it was changed to \\\"in the dead_items\\\". dead_items is\\n> > a variable name, and names don't take \\\"the\\\". \\\"into dead_items\\\" seems\\n> > most natural to me, but there are other possible phrasings.\\n>\\n> Thanks for the explanation. I was distracted. Fixed in the latest patch.\\n>\\n> >\\n> > > > > > Did you try it with 1MB m_w_m?\\n> > > > >\\n> > > > > I've incorporated the above comments and test results look good to me.\\n> > > >\\n> > > > Could you be more specific about what the test was?\\n> > > > Does it work with 1MB m_w_m?\\n> > >\\n> > > If m_w_m is 1MB, both the initial and maximum segment sizes are 256kB.\\n> > >\\n> > > FYI other test cases I tested were:\\n> > >\\n> > > * m_w_m = 2199023254528 (maximum value)\\n> > > initial: 1MB\\n> > > max: 128GB\\n> > >\\n> > > * m_w_m = 64MB (default)\\n> > > initial: 1MB\\n> > > max: 8MB\\n> >\\n> > If the test was a vacuum, how big a table was needed to hit 128GB?\\n>\\n> I just checked how TIdStoreCreateLocal() calculated the initial and\\n> max segment sizes while changing m_w_m, so didn't check how big\\n> segments are actually allocated in the maximum value test case.\\n>\\n> >\\n> > > > The existing comment slipped past my radar, but max_bytes is not a\\n> > > > limit, it's a hint. Come to think of it, it never was a limit in the\\n> > > > normal sense, but in earlier patches it was the criteria for reporting\\n> > > > \\\"I'm full\\\" when asked.\\n> > >\\n> > > Updated the comment.\\n> >\\n> > + * max_bytes is not a limit; it's used to choose the memory block sizes of\\n> > + * a memory context for TID storage in order for the total memory consumption\\n> > + * not to be overshot a lot. The caller can use the max_bytes as the criteria\\n> > + * for reporting whether it's full or not.\\n> >\\n> > This is good information. I suggest this edit:\\n> >\\n> > \\\"max_bytes\\\" is not an internally-enforced limit; it is used only as a\\n> > hint to cap the memory block size of the memory context for TID\\n> > storage. This reduces space wastage due to over-allocation. If the\\n> > caller wants to monitor memory usage, it must compare its limit with\\n> > the value reported by TidStoreMemoryUsage().\\n> >\\n> > Other comments:\\n>\\n> Thanks for the suggestion!\\n>\\n> >\\n> > v79-0002 looks good to me.\\n> >\\n> > v79-0003:\\n> >\\n> > \\\"With this commit, when creating a shared TidStore, a dedicated DSA\\n> > area is created for TID storage instead of using the provided DSA\\n> > area.\\\"\\n> >\\n> > This is very subtle, but \\\"the provided...\\\" implies there still is one.\\n> > -> \\\"a provided...\\\"\\n> >\\n> > + * Similar to TidStoreCreateLocal() but create a shared TidStore on a\\n> > + * DSA area. The TID storage will live in the DSA area, and a memory\\n> > + * context rt_context will have only meta data of the radix tree.\\n> >\\n> > -> \\\"the memory context\\\"\\n>\\n> Fixed in the latest patch.\\n>\\n> >\\n> > I think you can go ahead and commit 0002 and 0003/4.\\n>\\n> I've pushed the 0002 (dsa init and max segment size) patch, and will\\n> push the attached 0001 patch next.\\n\\nPushed the refactoring patch.\\n\\nI've attached the rebased vacuum improvement patch for cfbot. I\\nmentioned in the commit message that this patch eliminates the 1GB\\nlimitation.\\n\\nI think the patch is in good shape. Do you have other comments or\\nsuggestions, John?\\n\\nRegards,\\n\\n--\\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 28 Mar 2024 14:55:16 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 28, 2024 at 12:55 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> Pushed the refactoring patch.\\n>\\n> I've attached the rebased vacuum improvement patch for cfbot. I\\n> mentioned in the commit message that this patch eliminates the 1GB\\n> limitation.\\n>\\n> I think the patch is in good shape. Do you have other comments or\\n> suggestions, John?\\n\\nI'll do another pass tomorrow, but first I wanted to get in another\\nslightly-challenging in-situ test. On my humble laptop, I can still\\nfit a table large enough to cause PG16 to choke on multiple rounds of\\nindex cleanup:\\n\\ndrop table if exists test;\\ncreate unlogged table test (a int, b uuid) with (autovacuum_enabled=false);\\n\\ninsert into test (a,b) select i, gen_random_uuid() from\\ngenerate_series(1,1000*1000*1000) i;\\n\\ncreate index on test (a);\\ncreate index on test (b);\\n\\ndelete from test;\\n\\nvacuum (verbose, truncate off, parallel 2) test;\\n\\nINFO: vacuuming \\\"john.public.test\\\"\\nINFO: launched 1 parallel vacuum worker for index vacuuming (planned: 1)\\nINFO: finished vacuuming \\\"john.public.test\\\": index scans: 1\\npages: 0 removed, 6369427 remain, 6369427 scanned (100.00% of total)\\ntuples: 999997174 removed, 2826 remain, 0 are dead but not yet removable\\ntuples missed: 2826 dead from 18 pages not removed due to cleanup lock\\ncontention\\nremovable cutoff: 771, which was 0 XIDs old when operation ended\\nnew relfrozenxid: 767, which is 4 XIDs ahead of previous value\\nfrozen: 0 pages from table (0.00% of total) had 0 tuples frozen\\nindex scan needed: 6369409 pages from table (100.00% of total) had\\n999997174 dead item identifiers removed\\nindex \\\"test_a_idx\\\": pages: 2741898 in total, 2741825 newly deleted,\\n2741825 currently deleted, 0 reusable\\nindex \\\"test_b_idx\\\": pages: 3850387 in total, 3842056 newly deleted,\\n3842056 currently deleted, 0 reusable\\navg read rate: 159.740 MB/s, avg write rate: 161.726 MB/s\\nbuffer usage: 26367981 hits, 14958634 misses, 15144601 dirtied\\nWAL usage: 3 records, 1 full page images, 2050 bytes\\nsystem usage: CPU: user: 151.89 s, system: 193.54 s, elapsed: 731.59 s\\n\\nWatching pg_stat_progress_vacuum, dead_tuple_bytes got up to 398458880.\\n\\nAbout the \\\"tuples missed\\\" -- I didn't expect contention during this\\ntest. I believe that's completely unrelated behavior, but wanted to\\nmention it anyway, since I found it confusing.\\n\\n\\n\",\n \"msg_date\": \"Thu, 28 Mar 2024 16:15:28 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 28, 2024 at 6:15 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 28, 2024 at 12:55 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > Pushed the refactoring patch.\\n> >\\n> > I've attached the rebased vacuum improvement patch for cfbot. I\\n> > mentioned in the commit message that this patch eliminates the 1GB\\n> > limitation.\\n> >\\n> > I think the patch is in good shape. Do you have other comments or\\n> > suggestions, John?\\n>\\n> I'll do another pass tomorrow, but first I wanted to get in another\\n> slightly-challenging in-situ test.\\n\\nThanks!\\n\\n>\\n> About the \\\"tuples missed\\\" -- I didn't expect contention during this\\n> test. I believe that's completely unrelated behavior, but wanted to\\n> mention it anyway, since I found it confusing.\\n\\nI don't investigate it enough but bgwriter might be related to the contention.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Fri, 29 Mar 2024 15:05:36 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Mar 28, 2024 at 12:55 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> I think the patch is in good shape. Do you have other comments or\\n> suggestions, John?\\n\\n--- a/doc/src/sgml/config.sgml\\n+++ b/doc/src/sgml/config.sgml\\n@@ -1918,11 +1918,6 @@ include_dir 'conf.d'\\n too high. It may be useful to control for this by separately\\n setting <xref linkend=\\\"guc-autovacuum-work-mem\\\"/>.\\n </para>\\n- <para>\\n- Note that for the collection of dead tuple identifiers,\\n- <command>VACUUM</command> is only able to utilize up to a maximum of\\n- <literal>1GB</literal> of memory.\\n- </para>\\n </listitem>\\n </varlistentry>\\n\\nThis is mentioned twice for two different GUCs -- need to remove the\\nother one, too. Other than that, I just have minor nits:\\n\\n- * The major space usage for vacuuming is storage for the array of dead TIDs\\n+ * The major space usage for vacuuming is TID store, a storage for dead TIDs\\n\\nI think I've helped edit this sentence before, but I still don't quite\\nlike it. I'm thinking now \\\"is storage for the dead tuple IDs\\\".\\n\\n- * set upper bounds on the number of TIDs we can keep track of at once.\\n+ * set upper bounds on the maximum memory that can be used for keeping track\\n+ * of dead TIDs at once.\\n\\nI think \\\"maximum\\\" is redundant with \\\"upper bounds\\\".\\n\\nI also feel the commit message needs more \\\"meat\\\" -- we need to clearly\\nnarrate the features and benefits. I've attached how I would write it,\\nbut feel free to use what you like to match your taste.\\n\\nI've marked it Ready for Committer.\",\n \"msg_date\": \"Fri, 29 Mar 2024 14:21:32 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Fri, Mar 29, 2024 at 4:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Mar 28, 2024 at 12:55 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > I think the patch is in good shape. Do you have other comments or\\n> > suggestions, John?\\n>\\n> --- a/doc/src/sgml/config.sgml\\n> +++ b/doc/src/sgml/config.sgml\\n> @@ -1918,11 +1918,6 @@ include_dir 'conf.d'\\n> too high. It may be useful to control for this by separately\\n> setting <xref linkend=\\\"guc-autovacuum-work-mem\\\"/>.\\n> </para>\\n> - <para>\\n> - Note that for the collection of dead tuple identifiers,\\n> - <command>VACUUM</command> is only able to utilize up to a maximum of\\n> - <literal>1GB</literal> of memory.\\n> - </para>\\n> </listitem>\\n> </varlistentry>\\n>\\n> This is mentioned twice for two different GUCs -- need to remove the\\n> other one, too.\\n\\nGood catch, removed.\\n\\n> Other than that, I just have minor nits:\\n>\\n> - * The major space usage for vacuuming is storage for the array of dead TIDs\\n> + * The major space usage for vacuuming is TID store, a storage for dead TIDs\\n>\\n> I think I've helped edit this sentence before, but I still don't quite\\n> like it. I'm thinking now \\\"is storage for the dead tuple IDs\\\".\\n>\\n> - * set upper bounds on the number of TIDs we can keep track of at once.\\n> + * set upper bounds on the maximum memory that can be used for keeping track\\n> + * of dead TIDs at once.\\n>\\n> I think \\\"maximum\\\" is redundant with \\\"upper bounds\\\".\\n\\nFixed.\\n\\n>\\n> I also feel the commit message needs more \\\"meat\\\" -- we need to clearly\\n> narrate the features and benefits. I've attached how I would write it,\\n> but feel free to use what you like to match your taste.\\n\\nWell, that's much better than mine.\\n\\n>\\n> I've marked it Ready for Committer.\\n\\nThank you! I've attached the patch that I'm going to push tomorrow.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Mon, 1 Apr 2024 11:53:28 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 1, 2024 at 9:54 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> Thank you! I've attached the patch that I'm going to push tomorrow.\\n\\nExcellent!\\n\\nI've attached a mostly-polished update on runtime embeddable values,\\nstoring up to 3 offsets in the child pointer (1 on 32-bit platforms).\\nAs discussed, this includes a macro to cap max possible offset that\\ncan be stored in the bitmap, which I believe only reduces the valid\\noffset range for 32kB pages on 32-bit platforms. Even there, it allows\\nfor more line pointers than can possibly be useful. It also splits\\ninto two parts for readability. It would be committed in two pieces as\\nwell, since they are independently useful.\",\n \"msg_date\": \"Sun, 7 Apr 2024 09:08:40 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n> I've attached a mostly-polished update on runtime embeddable values,\\n> storing up to 3 offsets in the child pointer (1 on 32-bit platforms).\\n\\nAnd...since there's a new bump context patch, I wanted to anticipate\\nsqueezing an update on top of that, if that gets committed. 0004/5 are\\nthe v6 bump context, and 0006 uses it for vacuum. The rest are to show\\nit works -- the expected.out changes make possible problems in CI\\neasier to see. The allocation size is 16 bytes, so this difference is\\nentirely due to lack of chunk header:\\n\\naset: 6619136\\nbump: 5047296\\n\\n(Note: assert builds still have the chunk header for sanity checking,\\nso this was done in a more optimized build)\",\n \"msg_date\": \"Sun, 7 Apr 2024 16:44:56 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi,\\n\\nOn 2024-04-01 11:53:28 +0900, Masahiko Sawada wrote:\\n> On Fri, Mar 29, 2024 at 4:21 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> > I've marked it Ready for Committer.\\n>\\n> Thank you! I've attached the patch that I'm going to push tomorrow.\\n\\nLocally I ran a 32bit build with ubsan enabled (by accident actually), which\\ncomplains:\\n\\nperforming post-bootstrap initialization ...\\n----------------------------------- stderr -----------------------------------\\n../../../../../home/andres/src/postgresql/src/backend/access/common/tidstore.c:341:24: runtime error: member access within misaligned address 0xffb6258e for type 'struct BlocktableEntry', which requires 4 byte alignment\\n0xffb6258e: note: pointer points here\\n 00 00 02 00 01 40 dc e9 83 0b 80 48 70 ee 00 00 00 00 00 00 00 01 17 00 00 00 f8 d4 a6 ee e8 25\\n ^\\n #0 0x814097e in TidStoreSetBlockOffsets ../../../../../home/andres/src/postgresql/src/backend/access/common/tidstore.c:341\\n #1 0x826560a in dead_items_add ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:2889\\n #2 0x825f8da in lazy_scan_prune ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:1502\\n #3 0x825da71 in lazy_scan_heap ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:977\\n #4 0x825ad8f in heap_vacuum_rel ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:499\\n #5 0x8697e97 in table_relation_vacuum ../../../../../home/andres/src/postgresql/src/include/access/tableam.h:1725\\n #6 0x869fca6 in vacuum_rel ../../../../../home/andres/src/postgresql/src/backend/commands/vacuum.c:2206\\n #7 0x869a0fd in vacuum ../../../../../home/andres/src/postgresql/src/backend/commands/vacuum.c:622\\n #8 0x869986b in ExecVacuum ../../../../../home/andres/src/postgresql/src/backend/commands/vacuum.c:449\\n #9 0x8e5f832 in standard_ProcessUtility ../../../../../home/andres/src/postgresql/src/backend/tcop/utility.c:859\\n #10 0x8e5e5f6 in ProcessUtility ../../../../../home/andres/src/postgresql/src/backend/tcop/utility.c:523\\n #11 0x8e5b71a in PortalRunUtility ../../../../../home/andres/src/postgresql/src/backend/tcop/pquery.c:1158\\n #12 0x8e5be80 in PortalRunMulti ../../../../../home/andres/src/postgresql/src/backend/tcop/pquery.c:1315\\n #13 0x8e59f9b in PortalRun ../../../../../home/andres/src/postgresql/src/backend/tcop/pquery.c:791\\n #14 0x8e4d5f3 in exec_simple_query ../../../../../home/andres/src/postgresql/src/backend/tcop/postgres.c:1274\\n #15 0x8e55159 in PostgresMain ../../../../../home/andres/src/postgresql/src/backend/tcop/postgres.c:4680\\n #16 0x8e54445 in PostgresSingleUserMain ../../../../../home/andres/src/postgresql/src/backend/tcop/postgres.c:4136\\n #17 0x88bb55e in main ../../../../../home/andres/src/postgresql/src/backend/main/main.c:194\\n #18 0xf76f47c4 (/lib/i386-linux-gnu/libc.so.6+0x237c4) (BuildId: fe79efe6681a919714a4e119da2baac3a4953fbf)\\n #19 0xf76f4887 in __libc_start_main (/lib/i386-linux-gnu/libc.so.6+0x23887) (BuildId: fe79efe6681a919714a4e119da2baac3a4953fbf)\\n #20 0x80d40f7 in _start (/srv/dev/build/postgres/m-dev-assert-32/tmp_install/srv/dev/install/postgres/m-dev-assert-32/bin/postgres+0x80d40f7)\\n\\nSUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../../../../../home/andres/src/postgresql/src/backend/access/common/tidstore.c:341:24 in\\nAborted (core dumped)\\nchild process exited with exit code 134\\ninitdb: data directory \\\"/srv/dev/build/postgres/m-dev-assert-32/tmp_install/initdb-template\\\" not removed at user's request\\n\\n\\nAt first I was confused why CI didn't find this. Turns out that, for me, this\\nis only triggered without compiler optimizations, and I had used -O0 while CI\\nuses some optimizations.\\n\\nBacktrace:\\n#9 0x0814097f in TidStoreSetBlockOffsets (ts=0xb8dfde4, blkno=15, offsets=0xffb6275c, num_offsets=11)\\n at ../../../../../home/andres/src/postgresql/src/backend/access/common/tidstore.c:341\\n#10 0x0826560b in dead_items_add (vacrel=0xb8df6d4, blkno=15, offsets=0xffb6275c, num_offsets=11)\\n at ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:2889\\n#11 0x0825f8db in lazy_scan_prune (vacrel=0xb8df6d4, buf=24, blkno=15, page=0xeeb6c000 \\\"\\\", vmbuffer=729, all_visible_according_to_vm=false,\\n has_lpdead_items=0xffb62a1f) at ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:1502\\n#12 0x0825da72 in lazy_scan_heap (vacrel=0xb8df6d4) at ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:977\\n#13 0x0825ad90 in heap_vacuum_rel (rel=0xb872810, params=0xffb62e90, bstrategy=0xb99d5e0)\\n at ../../../../../home/andres/src/postgresql/src/backend/access/heap/vacuumlazy.c:499\\n#14 0x08697e98 in table_relation_vacuum (rel=0xb872810, params=0xffb62e90, bstrategy=0xb99d5e0)\\n at ../../../../../home/andres/src/postgresql/src/include/access/tableam.h:1725\\n#15 0x0869fca7 in vacuum_rel (relid=1249, relation=0x0, params=0xffb62e90, bstrategy=0xb99d5e0)\\n at ../../../../../home/andres/src/postgresql/src/backend/commands/vacuum.c:2206\\n#16 0x0869a0fe in vacuum (relations=0xb99de08, params=0xffb62e90, bstrategy=0xb99d5e0, vac_context=0xb99d550, isTopLevel=true)\\n\\n(gdb) p/x page\\n$1 = 0xffb6258e\\n\\n\\nI think compiler optimizations are only tangentially involved here, they\\ntrigger the stack frame layout to change, e.g. because some variable will just\\nexist in a register.\\n\\n\\nLooking at the code, the failure isn't suprising anymore:\\n\\tchar\\t\\tdata[MaxBlocktableEntrySize];\\n\\tBlocktableEntry *page = (BlocktableEntry *) data;\\n\\n'char' doesn't enforce any alignment, but you're storing a BlocktableEntry in\\na char[]. You can't just do that. Look at how we do that for\\ne.g. PGAlignedblock.\\n\\n\\nWith the attached minimal fix, the tests pass again.\\n\\nGreetings,\\n\\nAndres Freund\",\n \"msg_date\": \"Sun, 7 Apr 2024 12:07:31 -0700\",\n \"msg_from\": \"Andres Freund <andres@anarazel.de>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 8, 2024 at 2:07 AM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> Looking at the code, the failure isn't suprising anymore:\\n> char data[MaxBlocktableEntrySize];\\n> BlocktableEntry *page = (BlocktableEntry *) data;\\n>\\n> 'char' doesn't enforce any alignment, but you're storing a BlocktableEntry in\\n> a char[]. You can't just do that. Look at how we do that for\\n> e.g. PGAlignedblock.\\n>\\n>\\n> With the attached minimal fix, the tests pass again.\\n\\nThanks, will push this shortly!\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Apr 2024 06:13:04 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"Hi, John!\\n\\nOn Mon, 8 Apr 2024 at 03:13, John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> On Mon, Apr 8, 2024 at 2:07 AM Andres Freund <andres@anarazel.de> wrote:\\n> >\\n> > Looking at the code, the failure isn't suprising anymore:\\n> > char data[MaxBlocktableEntrySize];\\n> > BlocktableEntry *page = (BlocktableEntry *) data;\\n> >\\n> > 'char' doesn't enforce any alignment, but you're storing a\\n> BlocktableEntry in\\n> > a char[]. You can't just do that. Look at how we do that for\\n> > e.g. PGAlignedblock.\\n> >\\n> >\\n> > With the attached minimal fix, the tests pass again.\\n>\\n> Thanks, will push this shortly!\\n>\\nBuildfarm animal mylodon looks unhappy with this:\\n\\nFAILED: src/backend/postgres_lib.a.p/access_common_tidstore.c.o\\nccache clang-14 -Isrc/backend/postgres_lib.a.p -Isrc/include\\n-I../pgsql/src/include -I/usr/include/libxml2 -I/usr/include/security\\n-fdiagnostics-color=never -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch\\n-O2 -g -fno-strict-aliasing -fwrapv -D_GNU_SOURCE -Wmissing-prototypes\\n-Wpointer-arith -Werror=vla -Werror=unguarded-availability-new\\n-Wendif-labels -Wmissing-format-attribute -Wcast-function-type\\n-Wformat-security -Wdeclaration-after-statement\\n-Wno-unused-command-line-argument -Wno-compound-token-split-by-macro\\n-O1 -ggdb -g3 -fno-omit-frame-pointer -Wall -Wextra\\n-Wno-unused-parameter -Wno-sign-compare\\n-Wno-missing-field-initializers -Wno-array-bounds -std=c99\\n-Wc11-extensions -Werror=c11-extensions -fPIC -isystem\\n/usr/include/mit-krb5 -pthread -DBUILDING_DLL -MD -MQ\\nsrc/backend/postgres_lib.a.p/access_common_tidstore.c.o -MF\\nsrc/backend/postgres_lib.a.p/access_common_tidstore.c.o.d -o\\nsrc/backend/postgres_lib.a.p/access_common_tidstore.c.o -c\\n../pgsql/src/backend/access/common/tidstore.c\\n../pgsql/src/backend/access/common/tidstore.c:48:3: error: anonymous\\nstructs are a C11 extension [-Werror,-Wc11-extensions]\\n struct\\n ^\\n\\n1 error generated.\\n\\nRegards,\\nPavel Borisov\\nSupabase\\n\\nHi, John!On Mon, 8 Apr 2024 at 03:13, John Naylor <johncnaylorls@gmail.com> wrote:On Mon, Apr 8, 2024 at 2:07 AM Andres Freund <andres@anarazel.de> wrote:\\n>\\n> Looking at the code, the failure isn't suprising anymore:\\n> char data[MaxBlocktableEntrySize];\\n> BlocktableEntry *page = (BlocktableEntry *) data;\\n>\\n> 'char' doesn't enforce any alignment, but you're storing a BlocktableEntry in\\n> a char[]. You can't just do that. Look at how we do that for\\n> e.g. PGAlignedblock.\\n>\\n>\\n> With the attached minimal fix, the tests pass again.\\n\\nThanks, will push this shortly!Buildfarm animal mylodon looks unhappy with this:FAILED: src/backend/postgres_lib.a.p/access_common_tidstore.c.o \\nccache clang-14 -Isrc/backend/postgres_lib.a.p -Isrc/include -I../pgsql/src/include -I/usr/include/libxml2 -I/usr/include/security -fdiagnostics-color=never -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O2 -g -fno-strict-aliasing -fwrapv -D_GNU_SOURCE -Wmissing-prototypes -Wpointer-arith -Werror=vla -Werror=unguarded-availability-new -Wendif-labels -Wmissing-format-attribute -Wcast-function-type -Wformat-security -Wdeclaration-after-statement -Wno-unused-command-line-argument -Wno-compound-token-split-by-macro -O1 -ggdb -g3 -fno-omit-frame-pointer -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare -Wno-missing-field-initializers -Wno-array-bounds -std=c99 -Wc11-extensions -Werror=c11-extensions -fPIC -isystem /usr/include/mit-krb5 -pthread -DBUILDING_DLL -MD -MQ src/backend/postgres_lib.a.p/access_common_tidstore.c.o -MF src/backend/postgres_lib.a.p/access_common_tidstore.c.o.d -o src/backend/postgres_lib.a.p/access_common_tidstore.c.o -c ../pgsql/src/backend/access/common/tidstore.c\\n../pgsql/src/backend/access/common/tidstore.c:48:3: error: anonymous structs are a C11 extension [-Werror,-Wc11-extensions]\\n struct\\n ^ 1 error generated.Regards,Pavel BorisovSupabase\",\n \"msg_date\": \"Mon, 8 Apr 2024 16:22:28 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I've attached a mostly-polished update on runtime embeddable values,\\n> storing up to 3 offsets in the child pointer (1 on 32-bit platforms).\\n> As discussed, this includes a macro to cap max possible offset that\\n> can be stored in the bitmap, which I believe only reduces the valid\\n> offset range for 32kB pages on 32-bit platforms. Even there, it allows\\n> for more line pointers than can possibly be useful. It also splits\\n> into two parts for readability. It would be committed in two pieces as\\n> well, since they are independently useful.\\n\\nI pushed both of these and see that mylodon complains that anonymous\\nunions are a C11 feature. I'm not actually sure that the union with\\nuintptr_t is actually needed, though, since that's not accessed as\\nsuch here. The simplest thing seems to get rid if the union and name\\nthe inner struct \\\"header\\\", as in the attached.\",\n \"msg_date\": \"Mon, 8 Apr 2024 19:26:40 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, 8 Apr 2024 at 16:27, John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls@gmail.com>\\n> wrote:\\n> >\\n> > I've attached a mostly-polished update on runtime embeddable values,\\n> > storing up to 3 offsets in the child pointer (1 on 32-bit platforms).\\n> > As discussed, this includes a macro to cap max possible offset that\\n> > can be stored in the bitmap, which I believe only reduces the valid\\n> > offset range for 32kB pages on 32-bit platforms. Even there, it allows\\n> > for more line pointers than can possibly be useful. It also splits\\n> > into two parts for readability. It would be committed in two pieces as\\n> > well, since they are independently useful.\\n>\\n> I pushed both of these and see that mylodon complains that anonymous\\n> unions are a C11 feature. I'm not actually sure that the union with\\n> uintptr_t is actually needed, though, since that's not accessed as\\n> such here. The simplest thing seems to get rid if the union and name\\n> the inner struct \\\"header\\\", as in the attached.\\n>\\n\\nProvided uintptr_t is not accessed it might be good to get rid of it.\\n\\nMaybe this patch also need correction in this:\\n+#define NUM_FULL_OFFSETS ((sizeof(uintptr_t) - sizeof(uint8) -\\nsizeof(int8)) / sizeof(OffsetNumber))\\n\\nRegards,\\nPavel\\n\\nOn Mon, 8 Apr 2024 at 16:27, John Naylor <johncnaylorls@gmail.com> wrote:On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I've attached a mostly-polished update on runtime embeddable values,\\n> storing up to 3 offsets in the child pointer (1 on 32-bit platforms).\\n> As discussed, this includes a macro to cap max possible offset that\\n> can be stored in the bitmap, which I believe only reduces the valid\\n> offset range for 32kB pages on 32-bit platforms. Even there, it allows\\n> for more line pointers than can possibly be useful. It also splits\\n> into two parts for readability. It would be committed in two pieces as\\n> well, since they are independently useful.\\n\\nI pushed both of these and see that mylodon complains that anonymous\\nunions are a C11 feature. I'm not actually sure that the union with\\nuintptr_t is actually needed, though, since that's not accessed as\\nsuch here. The simplest thing seems to get rid if the union and name\\nthe inner struct \\\"header\\\", as in the attached.Provided uintptr_t is not accessed it might be good to get rid of it.Maybe this patch also need correction in this:+#define NUM_FULL_OFFSETS ((sizeof(uintptr_t) - sizeof(uint8) - sizeof(int8)) / sizeof(OffsetNumber))Regards,Pavel\",\n \"msg_date\": \"Mon, 8 Apr 2024 16:42:01 +0400\",\n \"msg_from\": \"Pavel Borisov <pashkin.elfe@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 8, 2024 at 7:42 PM Pavel Borisov <pashkin.elfe@gmail.com> wrote:\\n>\\n>> I pushed both of these and see that mylodon complains that anonymous\\n>> unions are a C11 feature. I'm not actually sure that the union with\\n>> uintptr_t is actually needed, though, since that's not accessed as\\n>> such here. The simplest thing seems to get rid if the union and name\\n>> the inner struct \\\"header\\\", as in the attached.\\n>\\n>\\n> Provided uintptr_t is not accessed it might be good to get rid of it.\\n>\\n> Maybe this patch also need correction in this:\\n> +#define NUM_FULL_OFFSETS ((sizeof(uintptr_t) - sizeof(uint8) - sizeof(int8)) / sizeof(OffsetNumber))\\n\\nFor full context the diff was\\n\\n-#define NUM_FULL_OFFSETS ((sizeof(bitmapword) - sizeof(uint16)) /\\nsizeof(OffsetNumber))\\n+#define NUM_FULL_OFFSETS ((sizeof(uintptr_t) - sizeof(uint8) -\\nsizeof(int8)) / sizeof(OffsetNumber))\\n\\nI wanted the former, from f35bd9bf35 , to be independently useful (in\\ncase the commit in question had some unresolvable issue), and its\\nintent is to fill struct padding when the array of bitmapword happens\\nto have length zero. Changing to uintptr_t for the size calculation\\nreflects the intent to fit in a (local) pointer, regardless of the\\nsize of a bitmapword. (If a DSA pointer happens to be a different size\\nfor some odd platform, it should still work, BTW.)\\n\\nMy thinking with the union was, for big-endian, to force the 'flags'\\nmember to where it can be set, but thinking again, it should still\\nwork if by happenstance the header was smaller than the child pointer:\\nA different bit would get tagged, but I believe that's irrelevant. The\\n'flags' member makes sure a byte is reserved for the tag, but it may\\nnot be where the tag is actually located, if that makes sense.\\n\\n\\n\",\n \"msg_date\": \"Mon, 8 Apr 2024 20:17:54 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 8, 2024 at 7:26 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I pushed both of these and see that mylodon complains that anonymous\\n> unions are a C11 feature. I'm not actually sure that the union with\\n> uintptr_t is actually needed, though, since that's not accessed as\\n> such here. The simplest thing seems to get rid if the union and name\\n> the inner struct \\\"header\\\", as in the attached.\\n\\nI pushed this with some comment adjustments.\\n\\n\\n\",\n \"msg_date\": \"Tue, 9 Apr 2024 16:22:34 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"I took a look at the coverage report from [1] and it seems pretty\\ngood, but there are a couple more tests we could do.\\n\\n- RT_KEY_GET_SHIFT is not covered for key=0:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L803\\n\\nThat should be fairly simple to add to the tests.\\n\\n- Some paths for single-value leaves are not covered:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L904\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L954\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2606\\n\\nHowever, these paths do get regression test coverage on 32-bit\\nmachines. 64-bit builds only have leaves in the TID store, which\\ndoesn't (currently) delete entries, and doesn't instantiate the tree\\nwith the debug option.\\n\\n- In RT_SET \\\"if (found)\\\" is not covered:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n\\nThat's because we don't yet have code that replaces an existing value\\nwith a value of a different length.\\n\\n- RT_FREE_RECURSE isn't well covered:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n\\nThe TID store test is pretty simple as far as distribution of block\\nkeys, and focuses more on the offset bitmaps. We could try to cover\\nall branches here, but it would make the test less readable, and it's\\nkind of the wrong place to do that anyway. test_radixtree.c does have\\na commented-out option to use shared memory, but that's for local\\ntesting and won't be reflected in the coverage report. Maybe it's\\nenough.\\n\\n- RT_DELETE: \\\"if (key > tree->ctl->max_val)\\\" is not covered:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2644\\n\\nThat should be easy to add.\\n\\n- RT_DUMP_NODE is not covered, and never called by default anyway:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2804\\n\\nIt seems we could just leave it alone since it's debug-only, but it's\\nalso a lot of lines. One idea is to use elog with DEBUG5 instead of\\ncommenting out the call sites, but that would cause a lot of noise.\\n\\n- TidStoreCreate* has some memory clamps that are not covered:\\n\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L179\\nhttps://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L234\\n\\nMaybe we could experiment with using 1MB for shared, and something\\nsmaller for local.\\n\\n[1] https://www.postgresql.org/message-id/20240414223305.m3i5eju6zylabvln%40awork3.anarazel.de\\n\\n\\n\",\n \"msg_date\": \"Mon, 15 Apr 2024 16:12:38 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 15, 2024 at 04:12:38PM +0700, John Naylor wrote:\\n> - Some paths for single-value leaves are not covered:\\n> \\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L904\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L954\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2606\\n> \\n> However, these paths do get regression test coverage on 32-bit\\n> machines. 64-bit builds only have leaves in the TID store, which\\n> doesn't (currently) delete entries, and doesn't instantiate the tree\\n> with the debug option.\\n> \\n> - In RT_SET \\\"if (found)\\\" is not covered:\\n> \\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n> \\n> That's because we don't yet have code that replaces an existing value\\n> with a value of a different length.\\n\\nI saw a SIGSEGV there when using tidstore to write a fix for something else.\\nPatch attached.\",\n \"msg_date\": \"Wed, 24 Apr 2024 14:03:19 -0700\",\n \"msg_from\": \"Noah Misch <noah@leadboat.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Mon, Apr 15, 2024 at 6:12 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> I took a look at the coverage report from [1] and it seems pretty\\n> good, but there are a couple more tests we could do.\\n\\nThank you for checking!\\n\\n>\\n> - RT_KEY_GET_SHIFT is not covered for key=0:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L803\\n>\\n> That should be fairly simple to add to the tests.\\n\\nThere are two paths to call RT_KEY_GET_SHIFT():\\n\\n1. RT_SET() -> RT_KEY_GET_SHIFT()\\n2. RT_SET() -> RT_EXTEND_UP() -> RT_KEY_GET_SHIFT()\\n\\nIn both cases, it's called when key > tree->ctl->max_val. Since the\\nminimum value of max_val is 255, RT_KEY_GET_SHIFT() is never called\\nwhen key=0.\\n\\n>\\n> - Some paths for single-value leaves are not covered:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L904\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L954\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2606\\n>\\n> However, these paths do get regression test coverage on 32-bit\\n> machines. 64-bit builds only have leaves in the TID store, which\\n> doesn't (currently) delete entries, and doesn't instantiate the tree\\n> with the debug option.\\n\\nRight.\\n\\n>\\n> - In RT_SET \\\"if (found)\\\" is not covered:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n>\\n> That's because we don't yet have code that replaces an existing value\\n> with a value of a different length.\\n\\nNoah reported an issue around that. We should incorporate the patch\\nand cover this code path.\\n\\n>\\n> - RT_FREE_RECURSE isn't well covered:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n>\\n> The TID store test is pretty simple as far as distribution of block\\n> keys, and focuses more on the offset bitmaps. We could try to cover\\n> all branches here, but it would make the test less readable, and it's\\n> kind of the wrong place to do that anyway. test_radixtree.c does have\\n> a commented-out option to use shared memory, but that's for local\\n> testing and won't be reflected in the coverage report. Maybe it's\\n> enough.\\n\\nAgreed.\\n\\n>\\n> - RT_DELETE: \\\"if (key > tree->ctl->max_val)\\\" is not covered:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2644\\n>\\n> That should be easy to add.\\n\\nAgreed. The patch is attached.\\n\\n>\\n> - RT_DUMP_NODE is not covered, and never called by default anyway:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2804\\n>\\n> It seems we could just leave it alone since it's debug-only, but it's\\n> also a lot of lines. One idea is to use elog with DEBUG5 instead of\\n> commenting out the call sites, but that would cause a lot of noise.\\n\\nI think we can leave it alone.\\n\\n>\\n> - TidStoreCreate* has some memory clamps that are not covered:\\n>\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L179\\n> https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L234\\n>\\n> Maybe we could experiment with using 1MB for shared, and something\\n> smaller for local.\\n\\nI've confirmed that the local and shared tidstore with small max sizes\\nsuch as 4kB and 1MB worked. Currently the max size is hard-coded in\\ntest_tidstore.c but if we use work_mem as the max size, we can pass\\ndifferent max sizes for local and shared in the test script.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 25 Apr 2024 10:36:02 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 25, 2024 at 6:03 AM Noah Misch <noah@leadboat.com> wrote:\\n>\\n> On Mon, Apr 15, 2024 at 04:12:38PM +0700, John Naylor wrote:\\n> > - Some paths for single-value leaves are not covered:\\n> >\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L904\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L954\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2606\\n> >\\n> > However, these paths do get regression test coverage on 32-bit\\n> > machines. 64-bit builds only have leaves in the TID store, which\\n> > doesn't (currently) delete entries, and doesn't instantiate the tree\\n> > with the debug option.\\n> >\\n> > - In RT_SET \\\"if (found)\\\" is not covered:\\n> >\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L1768\\n> >\\n> > That's because we don't yet have code that replaces an existing value\\n> > with a value of a different length.\\n>\\n> I saw a SIGSEGV there when using tidstore to write a fix for something else.\\n> Patch attached.\\n\\nGreat find, thank you for the patch!\\n\\nThe fix looks good to me. I think we can improve regression tests for\\nbetter coverage. In TidStore on a 64-bit machine, we can store 3\\noffsets in the header and these values are embedded to the leaf page.\\nWith more than 3 offsets, the value size becomes more than 16 bytes\\nand a single value leaf. Therefore, if we can add the test with the\\narray[1,2,3,4,100], we can cover the case of replacing a single-value\\nleaf with a different size new single-value leaf. Now we add 9 pairs\\nof do_gset_block_offset() and check_set_block_offsets(). If these are\\nannoying, we can remove the cases of array[1] and array[1,2].\\n\\nI've attached a new patch. In addition to the new test case I\\nmentioned, I've added some new comments and removed an unnecessary\\nadded line in test_tidstore.sql.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 25 Apr 2024 11:49:38 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 25, 2024 at 9:50 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> > I saw a SIGSEGV there when using tidstore to write a fix for something else.\\n> > Patch attached.\\n>\\n> Great find, thank you for the patch!\\n\\n+1\\n\\n(This occurred to me a few days ago, but I was far from my computer.)\\n\\nWith the purge function that Noah proposed, I believe we can also get\\nrid of the comment at the top of the .sql test file warning of a\\nmaintenance hazard:\\n...\\\"To avoid adding duplicates,\\n-- each call to do_set_block_offsets() should use different block\\n-- numbers.\\\"\\n\\nI found that it doesn't add any measurable time to run the test.\\n\\n> The fix looks good to me. I think we can improve regression tests for\\n> better coverage. In TidStore on a 64-bit machine, we can store 3\\n> offsets in the header and these values are embedded to the leaf page.\\n> With more than 3 offsets, the value size becomes more than 16 bytes\\n> and a single value leaf. Therefore, if we can add the test with the\\n> array[1,2,3,4,100], we can cover the case of replacing a single-value\\n> leaf with a different size new single-value leaf. Now we add 9 pairs\\n\\nGood idea.\\n\\n> of do_gset_block_offset() and check_set_block_offsets(). If these are\\n> annoying, we can remove the cases of array[1] and array[1,2].\\n\\nLet's keep those -- 32-bit platforms should also exercise this path.\\n\\n\\n\",\n \"msg_date\": \"Thu, 25 Apr 2024 10:17:06 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 25, 2024 at 12:17 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Apr 25, 2024 at 9:50 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > > I saw a SIGSEGV there when using tidstore to write a fix for something else.\\n> > > Patch attached.\\n> >\\n> > Great find, thank you for the patch!\\n>\\n> +1\\n>\\n> (This occurred to me a few days ago, but I was far from my computer.)\\n>\\n> With the purge function that Noah proposed, I believe we can also get\\n> rid of the comment at the top of the .sql test file warning of a\\n> maintenance hazard:\\n> ...\\\"To avoid adding duplicates,\\n> -- each call to do_set_block_offsets() should use different block\\n> -- numbers.\\\"\\n\\nGood point. Removed.\\n\\n>\\n> > of do_gset_block_offset() and check_set_block_offsets(). If these are\\n> > annoying, we can remove the cases of array[1] and array[1,2].\\n>\\n> Let's keep those -- 32-bit platforms should also exercise this path.\\n\\nAgreed.\\n\\nI've attached a new patch. I'll push it tonight, if there is no further comment.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Thu, 25 Apr 2024 13:38:28 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 25, 2024 at 1:38 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Thu, Apr 25, 2024 at 12:17 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n> >\\n> > On Thu, Apr 25, 2024 at 9:50 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> > >\\n> > > > I saw a SIGSEGV there when using tidstore to write a fix for something else.\\n> > > > Patch attached.\\n> > >\\n> > > Great find, thank you for the patch!\\n> >\\n> > +1\\n> >\\n> > (This occurred to me a few days ago, but I was far from my computer.)\\n> >\\n> > With the purge function that Noah proposed, I believe we can also get\\n> > rid of the comment at the top of the .sql test file warning of a\\n> > maintenance hazard:\\n> > ...\\\"To avoid adding duplicates,\\n> > -- each call to do_set_block_offsets() should use different block\\n> > -- numbers.\\\"\\n>\\n> Good point. Removed.\\n>\\n> >\\n> > > of do_gset_block_offset() and check_set_block_offsets(). If these are\\n> > > annoying, we can remove the cases of array[1] and array[1,2].\\n> >\\n> > Let's keep those -- 32-bit platforms should also exercise this path.\\n>\\n> Agreed.\\n>\\n> I've attached a new patch. I'll push it tonight, if there is no further comment.\\n>\\n\\nPushed.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\\n\\n\\n\",\n \"msg_date\": \"Thu, 25 Apr 2024 22:42:49 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Thu, Apr 25, 2024 at 8:36 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n>\\n> On Mon, Apr 15, 2024 at 6:12 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n\\n> > - RT_KEY_GET_SHIFT is not covered for key=0:\\n> >\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L803\\n> >\\n> > That should be fairly simple to add to the tests.\\n>\\n> There are two paths to call RT_KEY_GET_SHIFT():\\n>\\n> 1. RT_SET() -> RT_KEY_GET_SHIFT()\\n> 2. RT_SET() -> RT_EXTEND_UP() -> RT_KEY_GET_SHIFT()\\n>\\n> In both cases, it's called when key > tree->ctl->max_val. Since the\\n> minimum value of max_val is 255, RT_KEY_GET_SHIFT() is never called\\n> when key=0.\\n\\nAh, right, so it is dead code. Nothing to worry about, but it does\\npoint the way to some simplifications, which I've put together in the\\nattached.\\n\\n> > - RT_DELETE: \\\"if (key > tree->ctl->max_val)\\\" is not covered:\\n> >\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2644\\n> >\\n> > That should be easy to add.\\n>\\n> Agreed. The patch is attached.\\n\\nLGTM\\n\\n> > - TidStoreCreate* has some memory clamps that are not covered:\\n> >\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L179\\n> > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L234\\n> >\\n> > Maybe we could experiment with using 1MB for shared, and something\\n> > smaller for local.\\n>\\n> I've confirmed that the local and shared tidstore with small max sizes\\n> such as 4kB and 1MB worked. Currently the max size is hard-coded in\\n> test_tidstore.c but if we use work_mem as the max size, we can pass\\n> different max sizes for local and shared in the test script.\\n\\nSeems okay, do you want to try that and see how it looks?\",\n \"msg_date\": \"Wed, 1 May 2024 14:29:46 +0700\",\n \"msg_from\": \"John Naylor <johncnaylorls@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n },\n {\n \"msg_contents\": \"On Wed, May 1, 2024 at 4:29 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> On Thu, Apr 25, 2024 at 8:36 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:\\n> >\\n> > On Mon, Apr 15, 2024 at 6:12 PM John Naylor <johncnaylorls@gmail.com> wrote:\\n>\\n> > > - RT_KEY_GET_SHIFT is not covered for key=0:\\n> > >\\n> > > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L803\\n> > >\\n> > > That should be fairly simple to add to the tests.\\n> >\\n> > There are two paths to call RT_KEY_GET_SHIFT():\\n> >\\n> > 1. RT_SET() -> RT_KEY_GET_SHIFT()\\n> > 2. RT_SET() -> RT_EXTEND_UP() -> RT_KEY_GET_SHIFT()\\n> >\\n> > In both cases, it's called when key > tree->ctl->max_val. Since the\\n> > minimum value of max_val is 255, RT_KEY_GET_SHIFT() is never called\\n> > when key=0.\\n>\\n> Ah, right, so it is dead code. Nothing to worry about, but it does\\n> point the way to some simplifications, which I've put together in the\\n> attached.\\n\\nThank you for the patch. It looks good to me.\\n\\n+ /* compute the smallest shift that will allowing storing the key */\\n+ start_shift = pg_leftmost_one_pos64(key) / RT_SPAN * RT_SPAN;\\n\\nThe comment is moved from RT_KEY_GET_SHIFT() but I think s/will\\nallowing storing/will allow storing/.\\n\\n>\\n> > > - RT_DELETE: \\\"if (key > tree->ctl->max_val)\\\" is not covered:\\n> > >\\n> > > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/include/lib/radixtree.h.gcov.html#L2644\\n> > >\\n> > > That should be easy to add.\\n> >\\n> > Agreed. The patch is attached.\\n>\\n> LGTM\\n>\\n> > > - TidStoreCreate* has some memory clamps that are not covered:\\n> > >\\n> > > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L179\\n> > > https://anarazel.de/postgres/cov/16-vs-HEAD-2024-04-14/src/backend/access/common/tidstore.c.gcov.html#L234\\n> > >\\n> > > Maybe we could experiment with using 1MB for shared, and something\\n> > > smaller for local.\\n> >\\n> > I've confirmed that the local and shared tidstore with small max sizes\\n> > such as 4kB and 1MB worked. Currently the max size is hard-coded in\\n> > test_tidstore.c but if we use work_mem as the max size, we can pass\\n> > different max sizes for local and shared in the test script.\\n>\\n> Seems okay, do you want to try that and see how it looks?\\n\\nI've attached a simple patch for this. In test_tidstore.sql, we used\\nto create two local tidstore and one shared tidstore. I thought of\\nspecifying small work_mem values for these three cases but it would\\nremove the normal test cases. So I created separate tidstore for this\\ntest. Also, the new test is just to check if tidstore can be created\\nwith such a small size, but it might be a good idea to add some TIDs\\nto check if it really works fine.\\n\\nRegards,\\n\\n-- \\nMasahiko Sawada\\nAmazon Web Services: https://aws.amazon.com\",\n \"msg_date\": \"Wed, 8 May 2024 11:53:34 +0900\",\n \"msg_from\": \"Masahiko Sawada <sawada.mshk@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: [PoC] Improve dead tuple storage for lazy vacuum\"\n }\n]","isConversational":false}}},{"rowIdx":52497,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":">You can check the more details in the attached patch. Any feedback is\nwelcome.\n\nI have tiny comments about your patch:\n\n1. name of file is uniquekey.c?\n\n+ * pathkeys.c\n+ * Utilities for maintaining uniquekey.\n\n2. Variable \"PathKey *pathkey\" at function: add_uniquekey_for_uniqueindex,\ncan have scope reduced.\n\n+ indexpr_item = list_head(unique_index->indexprs);\n+ for (c = 0; c < unique_index->nkeycolumns; c++)\n+ {\n+ PathKey *pathkey;\n\n3. Variable int c = 0, has a redundant initialization at function:\nadd_uniquekey_for_uniqueindex.\n\n4. Has one word with misspelled?\n\n\"/* We can't *guarantee* an FuncExpr will not return NULLs */\"\n\n4. Variable int i = -1, has a redudant initialization at function:\nuniquekey_contains_in\n\n5. __attribute__ ((unused)) at function: build_composited_uniquekey, is\nincompatible with msvc.\n\n6. Postgres uses a newline after variables declarations.\n\nregards,\n\nRanier Vilela\n\n\n>You can check the more details in the attached patch. Any feedback is welcome.I have tiny comments about your patch:1. name of file is uniquekey.c?+ * pathkeys.c+ *\t Utilities for maintaining uniquekey.2. Variable \"PathKey\t*pathkey\" at function: add_uniquekey_for_uniqueindex, can have scope reduced.+\tindexpr_item = list_head(unique_index->indexprs);+\tfor (c = 0; c < unique_index->nkeycolumns; c++)+\t{+\t\tPathKey\t\t*pathkey;3. Variable int c = 0, has a redundant initialization at function:\nadd_uniquekey_for_uniqueindex.4. Has one word with misspelled? \"/* We can't *guarantee* an FuncExpr will not return NULLs */\"4. Variable int i = -1, has a redudant initialization at function: uniquekey_contains_in5. __attribute__ ((unused)) at function: build_composited_uniquekey, is incompatible with msvc.6. Postgres uses a newline after variables declarations.regards,Ranier Vilela","msg_date":"Wed, 7 Jul 2021 10:24:18 -0300","msg_from":"Ranier Vilela <ranier.vf@gmail.com>","msg_from_op":true,"msg_subject":"Re: Keep notnullattrs in RelOptInfo (Was part of UniqueKey patch\n series)"}],"string":"[\n {\n \"msg_contents\": \">You can check the more details in the attached patch. Any feedback is\\nwelcome.\\n\\nI have tiny comments about your patch:\\n\\n1. name of file is uniquekey.c?\\n\\n+ * pathkeys.c\\n+ * Utilities for maintaining uniquekey.\\n\\n2. Variable \\\"PathKey *pathkey\\\" at function: add_uniquekey_for_uniqueindex,\\ncan have scope reduced.\\n\\n+ indexpr_item = list_head(unique_index->indexprs);\\n+ for (c = 0; c < unique_index->nkeycolumns; c++)\\n+ {\\n+ PathKey *pathkey;\\n\\n3. Variable int c = 0, has a redundant initialization at function:\\nadd_uniquekey_for_uniqueindex.\\n\\n4. Has one word with misspelled?\\n\\n\\\"/* We can't *guarantee* an FuncExpr will not return NULLs */\\\"\\n\\n4. Variable int i = -1, has a redudant initialization at function:\\nuniquekey_contains_in\\n\\n5. __attribute__ ((unused)) at function: build_composited_uniquekey, is\\nincompatible with msvc.\\n\\n6. Postgres uses a newline after variables declarations.\\n\\nregards,\\n\\nRanier Vilela\\n\\n\\n>You can check the more details in the attached patch. Any feedback is welcome.I have tiny comments about your patch:1. name of file is uniquekey.c?+ * pathkeys.c+ *\\t Utilities for maintaining uniquekey.2. Variable \\\"PathKey\\t*pathkey\\\" at function: add_uniquekey_for_uniqueindex, can have scope reduced.+\\tindexpr_item = list_head(unique_index->indexprs);+\\tfor (c = 0; c < unique_index->nkeycolumns; c++)+\\t{+\\t\\tPathKey\\t\\t*pathkey;3. Variable int c = 0, has a redundant initialization at function:\\nadd_uniquekey_for_uniqueindex.4. Has one word with misspelled? \\\"/* We can't *guarantee* an FuncExpr will not return NULLs */\\\"4. Variable int i = -1, has a redudant initialization at function: uniquekey_contains_in5. __attribute__ ((unused)) at function: build_composited_uniquekey, is incompatible with msvc.6. Postgres uses a newline after variables declarations.regards,Ranier Vilela\",\n \"msg_date\": \"Wed, 7 Jul 2021 10:24:18 -0300\",\n \"msg_from\": \"Ranier Vilela <ranier.vf@gmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Keep notnullattrs in RelOptInfo (Was part of UniqueKey patch\\n series)\"\n }\n]","isConversational":false}}},{"rowIdx":52498,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi, hackers\n\nThe documentation [1] says:\n\nWhen dropping a subscription that is associated with a replication slot on the\nremote host (the normal state), DROP SUBSCRIPTION will connect to the remote\nhost and try to drop the replication slot as part of its operation. This is\nnecessary so that the resources allocated for the subscription on the remote\nhost are released. If this fails, either because the remote host is not\nreachable or because the remote replication slot cannot be dropped or does not\nexist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\nthis situation, disassociate the subscription from the replication slot by\nexecuting ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n\nHowever, when I try this, it complains the subscription is enabled, this command\nrequires the subscription disabled. Why we need this limitation?\n\nIn src/backend/commands/subscriptioncmds.c:\n\n if (IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))\n {\n if (sub->enabled && !opts.slot_name)\n ereport(ERROR,\n (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),\n errmsg(\"cannot set %s for enabled subscription\",\n \"slot_name = NONE\")));\n\n if (opts.slot_name)\n values[Anum_pg_subscription_subslotname - 1] =\n DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));\n else\n nulls[Anum_pg_subscription_subslotname - 1] = true;\n replaces[Anum_pg_subscription_subslotname - 1] = true;\n }\n\n\nOTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\nSELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\nshort. Although, the slot will be created at publisher, and validate the slot name, IMO, we\ncan also validate the slot_name in parse_subscription_options() to get the error early.\nAttached fixes it. Any thoughts?\n\n[1] https://www.postgresql.org/docs/current/sql-dropsubscription.html\n\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.","msg_date":"Wed, 07 Jul 2021 21:54:45 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n>\n> Hi, hackers\n>\n> The documentation [1] says:\n>\n> When dropping a subscription that is associated with a replication slot on the\n> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\n> host and try to drop the replication slot as part of its operation. This is\n> necessary so that the resources allocated for the subscription on the remote\n> host are released. If this fails, either because the remote host is not\n> reachable or because the remote replication slot cannot be dropped or does not\n> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\n> this situation, disassociate the subscription from the replication slot by\n> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n>\n> However, when I try this, it complains the subscription is enabled, this command\n> requires the subscription disabled. Why we need this limitation?\n>\n\nIf we don't have this limitation then even after you have set the slot\nname to none, the background apply worker corresponding to that\nsubscription will continue to stream changes via the previous slot.\n\n> In src/backend/commands/subscriptioncmds.c:\n>\n> if (IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))\n> {\n> if (sub->enabled && !opts.slot_name)\n> ereport(ERROR,\n> (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),\n> errmsg(\"cannot set %s for enabled subscription\",\n> \"slot_name = NONE\")));\n>\n> if (opts.slot_name)\n> values[Anum_pg_subscription_subslotname - 1] =\n> DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));\n> else\n> nulls[Anum_pg_subscription_subslotname - 1] = true;\n> replaces[Anum_pg_subscription_subslotname - 1] = true;\n> }\n>\n>\n> OTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\n> SELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\n> short. Although, the slot will be created at publisher, and validate the slot name, IMO, we\n> can also validate the slot_name in parse_subscription_options() to get the error early.\n> Attached fixes it. Any thoughts?\n>\n\nOh, I think this should be fixed. Can anyone else think this to be\nvalid behavior?\n\nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 8 Jul 2021 15:21:14 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"\nOn Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> Hi, hackers\n>>\n>> The documentation [1] says:\n>>\n>> When dropping a subscription that is associated with a replication slot on the\n>> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\n>> host and try to drop the replication slot as part of its operation. This is\n>> necessary so that the resources allocated for the subscription on the remote\n>> host are released. If this fails, either because the remote host is not\n>> reachable or because the remote replication slot cannot be dropped or does not\n>> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\n>> this situation, disassociate the subscription from the replication slot by\n>> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n>>\n>> However, when I try this, it complains the subscription is enabled, this command\n>> requires the subscription disabled. Why we need this limitation?\n>>\n>\n> If we don't have this limitation then even after you have set the slot\n> name to none, the background apply worker corresponding to that\n> subscription will continue to stream changes via the previous slot.\n>\n\nYeah, thanks for your explain! Should we add some comments here?\n\n>> OTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\n>> SELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\n>> short. Although, the slot will be created at publisher, and validate the slot name, IMO, we\n>> can also validate the slot_name in parse_subscription_options() to get the error early.\n>> Attached fixes it. Any thoughts?\n>>\n>\n> Oh, I think this should be fixed. Can anyone else think this to be\n> valid behavior?\n>\n\nRanier Vilela provides a v2 patch and reduce the overhead of\nReplicationSlotValidateName() in thread [1].\n\n[1] https://www.postgresql.org/message-id/CAEudQAqLtNJ1wvMKLK8ZH27SGJW5OjizgyMq28bFj-_5QG1G+A@mail.gmail.com\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.\n\n\n","msg_date":"Thu, 08 Jul 2021 18:13:24 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>\n> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n> >>\n> >> Hi, hackers\n> >>\n> >> The documentation [1] says:\n> >>\n> >> When dropping a subscription that is associated with a replication slot on the\n> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\n> >> host and try to drop the replication slot as part of its operation. This is\n> >> necessary so that the resources allocated for the subscription on the remote\n> >> host are released. If this fails, either because the remote host is not\n> >> reachable or because the remote replication slot cannot be dropped or does not\n> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\n> >> this situation, disassociate the subscription from the replication slot by\n> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n> >>\n> >> However, when I try this, it complains the subscription is enabled, this command\n> >> requires the subscription disabled. Why we need this limitation?\n> >>\n> >\n> > If we don't have this limitation then even after you have set the slot\n> > name to none, the background apply worker corresponding to that\n> > subscription will continue to stream changes via the previous slot.\n> >\n>\n> Yeah, thanks for your explain! Should we add some comments here?\n>\n\nSure, but let's keep that as a separate HEAD-only patch.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Thu, 8 Jul 2021 15:47:43 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n>> >>\n>> >> Hi, hackers\n>> >>\n>> >> The documentation [1] says:\n>> >>\n>> >> When dropping a subscription that is associated with a replication slot on the\n>> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\n>> >> host and try to drop the replication slot as part of its operation. This is\n>> >> necessary so that the resources allocated for the subscription on the remote\n>> >> host are released. If this fails, either because the remote host is not\n>> >> reachable or because the remote replication slot cannot be dropped or does not\n>> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\n>> >> this situation, disassociate the subscription from the replication slot by\n>> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n>> >>\n>> >> However, when I try this, it complains the subscription is enabled, this command\n>> >> requires the subscription disabled. Why we need this limitation?\n>> >>\n>> >\n>> > If we don't have this limitation then even after you have set the slot\n>> > name to none, the background apply worker corresponding to that\n>> > subscription will continue to stream changes via the previous slot.\n>> >\n>>\n>> Yeah, thanks for your explain! Should we add some comments here?\n>>\n>\n> Sure, but let's keep that as a separate HEAD-only patch.\n\nPlease consider review v3 patch. v3-0001 adds slot_name verification in\nparse_subscription_options() and comments for why we need disable subscription\nwhere set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce the\noverhead strlen in ReplicationSlotValidateName().\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.","msg_date":"Fri, 09 Jul 2021 10:49:54 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"Em qui., 8 de jul. de 2021 às 23:50, Japin Li <japinli@hotmail.com>\nescreveu:\n\n>\n> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n> >>\n> >> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com>\n> wrote:\n> >> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n> >> >>\n> >> >> Hi, hackers\n> >> >>\n> >> >> The documentation [1] says:\n> >> >>\n> >> >> When dropping a subscription that is associated with a replication\n> slot on the\n> >> >> remote host (the normal state), DROP SUBSCRIPTION will connect to\n> the remote\n> >> >> host and try to drop the replication slot as part of its operation.\n> This is\n> >> >> necessary so that the resources allocated for the subscription on\n> the remote\n> >> >> host are released. If this fails, either because the remote host is\n> not\n> >> >> reachable or because the remote replication slot cannot be dropped\n> or does not\n> >> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To\n> proceed in\n> >> >> this situation, disassociate the subscription from the replication\n> slot by\n> >> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n> >> >>\n> >> >> However, when I try this, it complains the subscription is enabled,\n> this command\n> >> >> requires the subscription disabled. Why we need this limitation?\n> >> >>\n> >> >\n> >> > If we don't have this limitation then even after you have set the slot\n> >> > name to none, the background apply worker corresponding to that\n> >> > subscription will continue to stream changes via the previous slot.\n> >> >\n> >>\n> >> Yeah, thanks for your explain! Should we add some comments here?\n> >>\n> >\n> > Sure, but let's keep that as a separate HEAD-only patch.\n>\n> Please consider review v3 patch. v3-0001 adds slot_name verification in\n> parse_subscription_options() and comments for why we need disable\n> subscription\n> where set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce\n> the\n> overhead strlen in ReplicationSlotValidateName().\n>\n+1 Seems good.\n\nregards,\nRanier Vilela\n\nEm qui., 8 de jul. de 2021 às 23:50, Japin Li <japinli@hotmail.com> escreveu:\nOn Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\n>> >>\n>> >> Hi, hackers\n>> >>\n>> >> The documentation [1] says:\n>> >>\n>> >> When dropping a subscription that is associated with a replication slot on the\n>> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\n>> >> host and try to drop the replication slot as part of its operation. This is\n>> >> necessary so that the resources allocated for the subscription on the remote\n>> >> host are released. If this fails, either because the remote host is not\n>> >> reachable or because the remote replication slot cannot be dropped or does not\n>> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\n>> >> this situation, disassociate the subscription from the replication slot by\n>> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\n>> >>\n>> >> However, when I try this, it complains the subscription is enabled, this command\n>> >> requires the subscription disabled. Why we need this limitation?\n>> >>\n>> >\n>> > If we don't have this limitation then even after you have set the slot\n>> > name to none, the background apply worker corresponding to that\n>> > subscription will continue to stream changes via the previous slot.\n>> >\n>>\n>> Yeah, thanks for your explain! Should we add some comments here?\n>>\n>\n> Sure, but let's keep that as a separate HEAD-only patch.\n\nPlease consider review v3 patch. v3-0001 adds slot_name verification in\nparse_subscription_options() and comments for why we need disable subscription\nwhere set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce the\noverhead strlen in ReplicationSlotValidateName().+1 Seems good.regards,Ranier Vilela","msg_date":"Fri, 9 Jul 2021 09:03:10 -0300","msg_from":"Ranier Vilela <ranier.vf@gmail.com>","msg_from_op":false,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\n>\n> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>\n> Please consider review v3 patch. v3-0001 adds slot_name verification in\n> parse_subscription_options() and comments for why we need disable subscription\n> where set slot_name to NONE.\n>\n\nI think we back-patch this bug-fix till v10 where it was introduced\nand update the comments only in HEAD. So, accordingly, I moved the\nchanges into two patches and changed the comments a bit. Can you\nplease test the first patch in back-branches? I'll also do it\nseparately.\n\n> v3-0002 comes from Ranier Vilela, it reduce the\n> overhead strlen in ReplicationSlotValidateName().\n>\n\nI think this patch has nothing to do with this bug-fix, so I suggest\nyou discuss this in a separate patch. Personally, I don't think it\nwill help in reducing any overhead but there doesn't appear to be any\nharm in changing it as proposed.\n\n-- \nWith Regards,\nAmit Kapila.","msg_date":"Fri, 16 Jul 2021 11:36:14 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"\nOn Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> Please consider review v3 patch. v3-0001 adds slot_name verification in\n>> parse_subscription_options() and comments for why we need disable subscription\n>> where set slot_name to NONE.\n>>\n>\n> I think we back-patch this bug-fix till v10 where it was introduced\n> and update the comments only in HEAD. So, accordingly, I moved the\n> changes into two patches and changed the comments a bit. Can you\n> please test the first patch in back-branches? I'll also do it\n> separately.\n>\n\nThanks for your review, I'll test the in back-branches.\n\n>> v3-0002 comes from Ranier Vilela, it reduce the\n>> overhead strlen in ReplicationSlotValidateName().\n>>\n>\n> I think this patch has nothing to do with this bug-fix, so I suggest\n> you discuss this in a separate patch. Personally, I don't think it\n> will help in reducing any overhead but there doesn't appear to be any\n> harm in changing it as proposed.\n\nAgreed.\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.\n\n\n","msg_date":"Fri, 16 Jul 2021 14:13:07 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>> Please consider review v3 patch. v3-0001 adds slot_name verification in\n>> parse_subscription_options() and comments for why we need disable subscription\n>> where set slot_name to NONE.\n>>\n>\n> I think we back-patch this bug-fix till v10 where it was introduced\n> and update the comments only in HEAD. So, accordingly, I moved the\n> changes into two patches and changed the comments a bit. Can you\n> please test the first patch in back-branches? I'll also do it\n> separately.\n>\n\nI try to back-patch to v10 stable to v14 stable, and attach two new patches:\none for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\nv4 patch can be applied on HEAD. This modify looks good to me.\n\nHow do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\nalways work (without a doubt, it might be some difference between branches).\n\n>> v3-0002 comes from Ranier Vilela, it reduce the\n>> overhead strlen in ReplicationSlotValidateName().\n>>\n>\n> I think this patch has nothing to do with this bug-fix, so I suggest\n> you discuss this in a separate patch. Personally, I don't think it\n> will help in reducing any overhead but there doesn't appear to be any\n> harm in changing it as proposed.\n\nI start a new thread to discuss this [1].\n\n[1] - https://www.postgresql.org/message-id/MEYP282MB16696F6DBA8AE36A648817B2B6119@MEYP282MB1669.AUSP282.PROD.OUTLOOK.COM\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.","msg_date":"Fri, 16 Jul 2021 16:42:01 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"On Fri, Jul 16, 2021 at 2:12 PM Japin Li <japinli@hotmail.com> wrote:\n>\n>\n> On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> > On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\n> >>\n> >> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> >> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n> >>\n> >> Please consider review v3 patch. v3-0001 adds slot_name verification in\n> >> parse_subscription_options() and comments for why we need disable subscription\n> >> where set slot_name to NONE.\n> >>\n> >\n> > I think we back-patch this bug-fix till v10 where it was introduced\n> > and update the comments only in HEAD. So, accordingly, I moved the\n> > changes into two patches and changed the comments a bit. Can you\n> > please test the first patch in back-branches? I'll also do it\n> > separately.\n> >\n>\n> I try to back-patch to v10 stable to v14 stable, and attach two new patches:\n> one for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\n> v4 patch can be applied on HEAD. This modify looks good to me.\n>\n\nThe patch you prepared for v14 was not getting applied cleanly, so I\ndid the required modifications and then pushed.\n\n> How do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\n> always work (without a doubt, it might be some difference between branches).\n>\n\nYeah, we need to adjust the patch as per the back-branches code.\n\n-- \nWith Regards,\nAmit Kapila.\n\n\n","msg_date":"Mon, 19 Jul 2021 14:32:10 +0530","msg_from":"Amit Kapila <amit.kapila16@gmail.com>","msg_from_op":false,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"},{"msg_contents":"\nOn Mon, 19 Jul 2021 at 17:02, Amit Kapila <amit.kapila16@gmail.com> wrote:\n> On Fri, Jul 16, 2021 at 2:12 PM Japin Li <japinli@hotmail.com> wrote:\n>>\n>>\n>> On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> > On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\n>> >>\n>> >> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\n>> >> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\n>> >>\n>> >> Please consider review v3 patch. v3-0001 adds slot_name verification in\n>> >> parse_subscription_options() and comments for why we need disable subscription\n>> >> where set slot_name to NONE.\n>> >>\n>> >\n>> > I think we back-patch this bug-fix till v10 where it was introduced\n>> > and update the comments only in HEAD. So, accordingly, I moved the\n>> > changes into two patches and changed the comments a bit. Can you\n>> > please test the first patch in back-branches? I'll also do it\n>> > separately.\n>> >\n>>\n>> I try to back-patch to v10 stable to v14 stable, and attach two new patches:\n>> one for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\n>> v4 patch can be applied on HEAD. This modify looks good to me.\n>>\n>\n> The patch you prepared for v14 was not getting applied cleanly, so I\n> did the required modifications and then pushed.\n>\n>> How do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\n>> always work (without a doubt, it might be some difference between branches).\n>>\n>\n> Yeah, we need to adjust the patch as per the back-branches code.\n\nThanks!\n\n-- \nRegrads,\nJapin Li.\nChengDu WenWu Information Technology Co.,Ltd.\n\n\n","msg_date":"Tue, 20 Jul 2021 09:59:53 +0800","msg_from":"Japin Li <japinli@hotmail.com>","msg_from_op":true,"msg_subject":"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\n subscription disabled?"}],"string":"[\n {\n \"msg_contents\": \"Hi, hackers\\n\\nThe documentation [1] says:\\n\\nWhen dropping a subscription that is associated with a replication slot on the\\nremote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\nhost and try to drop the replication slot as part of its operation. This is\\nnecessary so that the resources allocated for the subscription on the remote\\nhost are released. If this fails, either because the remote host is not\\nreachable or because the remote replication slot cannot be dropped or does not\\nexist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\nthis situation, disassociate the subscription from the replication slot by\\nexecuting ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n\\nHowever, when I try this, it complains the subscription is enabled, this command\\nrequires the subscription disabled. Why we need this limitation?\\n\\nIn src/backend/commands/subscriptioncmds.c:\\n\\n if (IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))\\n {\\n if (sub->enabled && !opts.slot_name)\\n ereport(ERROR,\\n (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),\\n errmsg(\\\"cannot set %s for enabled subscription\\\",\\n \\\"slot_name = NONE\\\")));\\n\\n if (opts.slot_name)\\n values[Anum_pg_subscription_subslotname - 1] =\\n DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));\\n else\\n nulls[Anum_pg_subscription_subslotname - 1] = true;\\n replaces[Anum_pg_subscription_subslotname - 1] = true;\\n }\\n\\n\\nOTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\\nSELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\\nshort. Although, the slot will be created at publisher, and validate the slot name, IMO, we\\ncan also validate the slot_name in parse_subscription_options() to get the error early.\\nAttached fixes it. Any thoughts?\\n\\n[1] https://www.postgresql.org/docs/current/sql-dropsubscription.html\\n\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\",\n \"msg_date\": \"Wed, 07 Jul 2021 21:54:45 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n>\\n> Hi, hackers\\n>\\n> The documentation [1] says:\\n>\\n> When dropping a subscription that is associated with a replication slot on the\\n> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\n> host and try to drop the replication slot as part of its operation. This is\\n> necessary so that the resources allocated for the subscription on the remote\\n> host are released. If this fails, either because the remote host is not\\n> reachable or because the remote replication slot cannot be dropped or does not\\n> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\n> this situation, disassociate the subscription from the replication slot by\\n> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n>\\n> However, when I try this, it complains the subscription is enabled, this command\\n> requires the subscription disabled. Why we need this limitation?\\n>\\n\\nIf we don't have this limitation then even after you have set the slot\\nname to none, the background apply worker corresponding to that\\nsubscription will continue to stream changes via the previous slot.\\n\\n> In src/backend/commands/subscriptioncmds.c:\\n>\\n> if (IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))\\n> {\\n> if (sub->enabled && !opts.slot_name)\\n> ereport(ERROR,\\n> (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),\\n> errmsg(\\\"cannot set %s for enabled subscription\\\",\\n> \\\"slot_name = NONE\\\")));\\n>\\n> if (opts.slot_name)\\n> values[Anum_pg_subscription_subslotname - 1] =\\n> DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));\\n> else\\n> nulls[Anum_pg_subscription_subslotname - 1] = true;\\n> replaces[Anum_pg_subscription_subslotname - 1] = true;\\n> }\\n>\\n>\\n> OTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\\n> SELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\\n> short. Although, the slot will be created at publisher, and validate the slot name, IMO, we\\n> can also validate the slot_name in parse_subscription_options() to get the error early.\\n> Attached fixes it. Any thoughts?\\n>\\n\\nOh, I think this should be fixed. Can anyone else think this to be\\nvalid behavior?\\n\\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 8 Jul 2021 15:21:14 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"\\nOn Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> Hi, hackers\\n>>\\n>> The documentation [1] says:\\n>>\\n>> When dropping a subscription that is associated with a replication slot on the\\n>> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\n>> host and try to drop the replication slot as part of its operation. This is\\n>> necessary so that the resources allocated for the subscription on the remote\\n>> host are released. If this fails, either because the remote host is not\\n>> reachable or because the remote replication slot cannot be dropped or does not\\n>> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\n>> this situation, disassociate the subscription from the replication slot by\\n>> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n>>\\n>> However, when I try this, it complains the subscription is enabled, this command\\n>> requires the subscription disabled. Why we need this limitation?\\n>>\\n>\\n> If we don't have this limitation then even after you have set the slot\\n> name to none, the background apply worker corresponding to that\\n> subscription will continue to stream changes via the previous slot.\\n>\\n\\nYeah, thanks for your explain! Should we add some comments here?\\n\\n>> OTOH, when I execute ALTER SUBSCRIPTION ... SET (slot_name=''), it doesn't complain. However,\\n>> SELECT select pg_create_logical_replication_slot('', 'pgoutput') complains slot name is too\\n>> short. Although, the slot will be created at publisher, and validate the slot name, IMO, we\\n>> can also validate the slot_name in parse_subscription_options() to get the error early.\\n>> Attached fixes it. Any thoughts?\\n>>\\n>\\n> Oh, I think this should be fixed. Can anyone else think this to be\\n> valid behavior?\\n>\\n\\nRanier Vilela provides a v2 patch and reduce the overhead of\\nReplicationSlotValidateName() in thread [1].\\n\\n[1] https://www.postgresql.org/message-id/CAEudQAqLtNJ1wvMKLK8ZH27SGJW5OjizgyMq28bFj-_5QG1G+A@mail.gmail.com\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\\n\\n\\n\",\n \"msg_date\": \"Thu, 08 Jul 2021 18:13:24 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>\\n> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n> >>\\n> >> Hi, hackers\\n> >>\\n> >> The documentation [1] says:\\n> >>\\n> >> When dropping a subscription that is associated with a replication slot on the\\n> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\n> >> host and try to drop the replication slot as part of its operation. This is\\n> >> necessary so that the resources allocated for the subscription on the remote\\n> >> host are released. If this fails, either because the remote host is not\\n> >> reachable or because the remote replication slot cannot be dropped or does not\\n> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\n> >> this situation, disassociate the subscription from the replication slot by\\n> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n> >>\\n> >> However, when I try this, it complains the subscription is enabled, this command\\n> >> requires the subscription disabled. Why we need this limitation?\\n> >>\\n> >\\n> > If we don't have this limitation then even after you have set the slot\\n> > name to none, the background apply worker corresponding to that\\n> > subscription will continue to stream changes via the previous slot.\\n> >\\n>\\n> Yeah, thanks for your explain! Should we add some comments here?\\n>\\n\\nSure, but let's keep that as a separate HEAD-only patch.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Thu, 8 Jul 2021 15:47:43 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n>> >>\\n>> >> Hi, hackers\\n>> >>\\n>> >> The documentation [1] says:\\n>> >>\\n>> >> When dropping a subscription that is associated with a replication slot on the\\n>> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\n>> >> host and try to drop the replication slot as part of its operation. This is\\n>> >> necessary so that the resources allocated for the subscription on the remote\\n>> >> host are released. If this fails, either because the remote host is not\\n>> >> reachable or because the remote replication slot cannot be dropped or does not\\n>> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\n>> >> this situation, disassociate the subscription from the replication slot by\\n>> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n>> >>\\n>> >> However, when I try this, it complains the subscription is enabled, this command\\n>> >> requires the subscription disabled. Why we need this limitation?\\n>> >>\\n>> >\\n>> > If we don't have this limitation then even after you have set the slot\\n>> > name to none, the background apply worker corresponding to that\\n>> > subscription will continue to stream changes via the previous slot.\\n>> >\\n>>\\n>> Yeah, thanks for your explain! Should we add some comments here?\\n>>\\n>\\n> Sure, but let's keep that as a separate HEAD-only patch.\\n\\nPlease consider review v3 patch. v3-0001 adds slot_name verification in\\nparse_subscription_options() and comments for why we need disable subscription\\nwhere set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce the\\noverhead strlen in ReplicationSlotValidateName().\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\",\n \"msg_date\": \"Fri, 09 Jul 2021 10:49:54 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"Em qui., 8 de jul. de 2021 às 23:50, Japin Li <japinli@hotmail.com>\\nescreveu:\\n\\n>\\n> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n> >>\\n> >> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com>\\n> wrote:\\n> >> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n> >> >>\\n> >> >> Hi, hackers\\n> >> >>\\n> >> >> The documentation [1] says:\\n> >> >>\\n> >> >> When dropping a subscription that is associated with a replication\\n> slot on the\\n> >> >> remote host (the normal state), DROP SUBSCRIPTION will connect to\\n> the remote\\n> >> >> host and try to drop the replication slot as part of its operation.\\n> This is\\n> >> >> necessary so that the resources allocated for the subscription on\\n> the remote\\n> >> >> host are released. If this fails, either because the remote host is\\n> not\\n> >> >> reachable or because the remote replication slot cannot be dropped\\n> or does not\\n> >> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To\\n> proceed in\\n> >> >> this situation, disassociate the subscription from the replication\\n> slot by\\n> >> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n> >> >>\\n> >> >> However, when I try this, it complains the subscription is enabled,\\n> this command\\n> >> >> requires the subscription disabled. Why we need this limitation?\\n> >> >>\\n> >> >\\n> >> > If we don't have this limitation then even after you have set the slot\\n> >> > name to none, the background apply worker corresponding to that\\n> >> > subscription will continue to stream changes via the previous slot.\\n> >> >\\n> >>\\n> >> Yeah, thanks for your explain! Should we add some comments here?\\n> >>\\n> >\\n> > Sure, but let's keep that as a separate HEAD-only patch.\\n>\\n> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n> parse_subscription_options() and comments for why we need disable\\n> subscription\\n> where set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce\\n> the\\n> overhead strlen in ReplicationSlotValidateName().\\n>\\n+1 Seems good.\\n\\nregards,\\nRanier Vilela\\n\\nEm qui., 8 de jul. de 2021 às 23:50, Japin Li <japinli@hotmail.com> escreveu:\\nOn Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> On Thu, 08 Jul 2021 at 17:51, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> > On Wed, Jul 7, 2021 at 7:25 PM Japin Li <japinli@hotmail.com> wrote:\\n>> >>\\n>> >> Hi, hackers\\n>> >>\\n>> >> The documentation [1] says:\\n>> >>\\n>> >> When dropping a subscription that is associated with a replication slot on the\\n>> >> remote host (the normal state), DROP SUBSCRIPTION will connect to the remote\\n>> >> host and try to drop the replication slot as part of its operation. This is\\n>> >> necessary so that the resources allocated for the subscription on the remote\\n>> >> host are released. If this fails, either because the remote host is not\\n>> >> reachable or because the remote replication slot cannot be dropped or does not\\n>> >> exist or never existed, the DROP SUBSCRIPTION command will fail. To proceed in\\n>> >> this situation, disassociate the subscription from the replication slot by\\n>> >> executing ALTER SUBSCRIPTION ... SET (slot_name = NONE).\\n>> >>\\n>> >> However, when I try this, it complains the subscription is enabled, this command\\n>> >> requires the subscription disabled. Why we need this limitation?\\n>> >>\\n>> >\\n>> > If we don't have this limitation then even after you have set the slot\\n>> > name to none, the background apply worker corresponding to that\\n>> > subscription will continue to stream changes via the previous slot.\\n>> >\\n>>\\n>> Yeah, thanks for your explain! Should we add some comments here?\\n>>\\n>\\n> Sure, but let's keep that as a separate HEAD-only patch.\\n\\nPlease consider review v3 patch. v3-0001 adds slot_name verification in\\nparse_subscription_options() and comments for why we need disable subscription\\nwhere set slot_name to NONE. v3-0002 comes from Ranier Vilela, it reduce the\\noverhead strlen in ReplicationSlotValidateName().+1 Seems good.regards,Ranier Vilela\",\n \"msg_date\": \"Fri, 9 Jul 2021 09:03:10 -0300\",\n \"msg_from\": \"Ranier Vilela <ranier.vf@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\\n>\\n> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>\\n> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n> parse_subscription_options() and comments for why we need disable subscription\\n> where set slot_name to NONE.\\n>\\n\\nI think we back-patch this bug-fix till v10 where it was introduced\\nand update the comments only in HEAD. So, accordingly, I moved the\\nchanges into two patches and changed the comments a bit. Can you\\nplease test the first patch in back-branches? I'll also do it\\nseparately.\\n\\n> v3-0002 comes from Ranier Vilela, it reduce the\\n> overhead strlen in ReplicationSlotValidateName().\\n>\\n\\nI think this patch has nothing to do with this bug-fix, so I suggest\\nyou discuss this in a separate patch. Personally, I don't think it\\nwill help in reducing any overhead but there doesn't appear to be any\\nharm in changing it as proposed.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\",\n \"msg_date\": \"Fri, 16 Jul 2021 11:36:14 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"\\nOn Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n>> parse_subscription_options() and comments for why we need disable subscription\\n>> where set slot_name to NONE.\\n>>\\n>\\n> I think we back-patch this bug-fix till v10 where it was introduced\\n> and update the comments only in HEAD. So, accordingly, I moved the\\n> changes into two patches and changed the comments a bit. Can you\\n> please test the first patch in back-branches? I'll also do it\\n> separately.\\n>\\n\\nThanks for your review, I'll test the in back-branches.\\n\\n>> v3-0002 comes from Ranier Vilela, it reduce the\\n>> overhead strlen in ReplicationSlotValidateName().\\n>>\\n>\\n> I think this patch has nothing to do with this bug-fix, so I suggest\\n> you discuss this in a separate patch. Personally, I don't think it\\n> will help in reducing any overhead but there doesn't appear to be any\\n> harm in changing it as proposed.\\n\\nAgreed.\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\\n\\n\\n\",\n \"msg_date\": \"Fri, 16 Jul 2021 14:13:07 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n>> parse_subscription_options() and comments for why we need disable subscription\\n>> where set slot_name to NONE.\\n>>\\n>\\n> I think we back-patch this bug-fix till v10 where it was introduced\\n> and update the comments only in HEAD. So, accordingly, I moved the\\n> changes into two patches and changed the comments a bit. Can you\\n> please test the first patch in back-branches? I'll also do it\\n> separately.\\n>\\n\\nI try to back-patch to v10 stable to v14 stable, and attach two new patches:\\none for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\\nv4 patch can be applied on HEAD. This modify looks good to me.\\n\\nHow do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\\nalways work (without a doubt, it might be some difference between branches).\\n\\n>> v3-0002 comes from Ranier Vilela, it reduce the\\n>> overhead strlen in ReplicationSlotValidateName().\\n>>\\n>\\n> I think this patch has nothing to do with this bug-fix, so I suggest\\n> you discuss this in a separate patch. Personally, I don't think it\\n> will help in reducing any overhead but there doesn't appear to be any\\n> harm in changing it as proposed.\\n\\nI start a new thread to discuss this [1].\\n\\n[1] - https://www.postgresql.org/message-id/MEYP282MB16696F6DBA8AE36A648817B2B6119@MEYP282MB1669.AUSP282.PROD.OUTLOOK.COM\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\",\n \"msg_date\": \"Fri, 16 Jul 2021 16:42:01 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"On Fri, Jul 16, 2021 at 2:12 PM Japin Li <japinli@hotmail.com> wrote:\\n>\\n>\\n> On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> > On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\\n> >>\\n> >> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> >> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n> >>\\n> >> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n> >> parse_subscription_options() and comments for why we need disable subscription\\n> >> where set slot_name to NONE.\\n> >>\\n> >\\n> > I think we back-patch this bug-fix till v10 where it was introduced\\n> > and update the comments only in HEAD. So, accordingly, I moved the\\n> > changes into two patches and changed the comments a bit. Can you\\n> > please test the first patch in back-branches? I'll also do it\\n> > separately.\\n> >\\n>\\n> I try to back-patch to v10 stable to v14 stable, and attach two new patches:\\n> one for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\\n> v4 patch can be applied on HEAD. This modify looks good to me.\\n>\\n\\nThe patch you prepared for v14 was not getting applied cleanly, so I\\ndid the required modifications and then pushed.\\n\\n> How do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\\n> always work (without a doubt, it might be some difference between branches).\\n>\\n\\nYeah, we need to adjust the patch as per the back-branches code.\\n\\n-- \\nWith Regards,\\nAmit Kapila.\\n\\n\\n\",\n \"msg_date\": \"Mon, 19 Jul 2021 14:32:10 +0530\",\n \"msg_from\": \"Amit Kapila <amit.kapila16@gmail.com>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n },\n {\n \"msg_contents\": \"\\nOn Mon, 19 Jul 2021 at 17:02, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n> On Fri, Jul 16, 2021 at 2:12 PM Japin Li <japinli@hotmail.com> wrote:\\n>>\\n>>\\n>> On Fri, 16 Jul 2021 at 14:06, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> > On Fri, Jul 9, 2021 at 8:20 AM Japin Li <japinli@hotmail.com> wrote:\\n>> >>\\n>> >> On Thu, 08 Jul 2021 at 18:17, Amit Kapila <amit.kapila16@gmail.com> wrote:\\n>> >> > On Thu, Jul 8, 2021 at 3:43 PM Japin Li <japinli@hotmail.com> wrote:\\n>> >>\\n>> >> Please consider review v3 patch. v3-0001 adds slot_name verification in\\n>> >> parse_subscription_options() and comments for why we need disable subscription\\n>> >> where set slot_name to NONE.\\n>> >>\\n>> >\\n>> > I think we back-patch this bug-fix till v10 where it was introduced\\n>> > and update the comments only in HEAD. So, accordingly, I moved the\\n>> > changes into two patches and changed the comments a bit. Can you\\n>> > please test the first patch in back-branches? I'll also do it\\n>> > separately.\\n>> >\\n>>\\n>> I try to back-patch to v10 stable to v14 stable, and attach two new patches:\\n>> one for PG10 & PG11 stable, and the other is for PG12 to PG14 stable.\\n>> v4 patch can be applied on HEAD. This modify looks good to me.\\n>>\\n>\\n> The patch you prepared for v14 was not getting applied cleanly, so I\\n> did the required modifications and then pushed.\\n>\\n>> How do we back-patch to back-branches? I try to use cherry-pick, but it doesn't\\n>> always work (without a doubt, it might be some difference between branches).\\n>>\\n>\\n> Yeah, we need to adjust the patch as per the back-branches code.\\n\\nThanks!\\n\\n-- \\nRegrads,\\nJapin Li.\\nChengDu WenWu Information Technology Co.,Ltd.\\n\\n\\n\",\n \"msg_date\": \"Tue, 20 Jul 2021 09:59:53 +0800\",\n \"msg_from\": \"Japin Li <japinli@hotmail.com>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"Re: Why ALTER SUBSCRIPTION ... SET (slot_name='none') requires\\n subscription disabled?\"\n }\n]","isConversational":false}}},{"rowIdx":52499,"cells":{"threads":{"kind":"list like","value":[{"msg_contents":"Hi.\n\nThe following test case makes postgresql backend crash. The trigger is \nincorrect, but this didn't crash postgresql before\n\ncommit 86dc90056dfdbd9d1b891718d2e5614e3e432f35 (HEAD)\nAuthor: Tom Lane <tgl@sss.pgh.pa.us>\nDate: Wed Mar 31 11:52:34 2021 -0400\n\n Rework planning and execution of UPDATE and DELETE.\n\n\nProgram terminated with signal SIGSEGV, Segmentation fault.\n#0 0x00007f1032cc6905 in find_modifytable_subplan (root=0x563f05e61458, \nplan=0x563f06020e48, rtindex=1, subplan_index=0) at postgres_fdw.c:2373\n2373 else if (IsA(subplan, Result) && IsA(outerPlan(subplan), \nAppend))\n(gdb) bt\n#0 0x00007f1032cc6905 in find_modifytable_subplan (root=0x563f05e61458, \nplan=0x563f06020e48, rtindex=1, subplan_index=0) at postgres_fdw.c:2373\n#1 0x00007f1032cc6a44 in postgresPlanDirectModify (root=0x563f05e61458, \nplan=0x563f06020e48, resultRelation=1, subplan_index=0) at \npostgres_fdw.c:2433\n#2 0x0000563f035f2876 in make_modifytable (root=0x563f05e61458, \nsubplan=0x563f05e626e8, operation=CMD_DELETE, canSetTag=true, \nnominalRelation=1, rootRelation=0, partColsUpdated=false, \nresultRelations=0x563f06020b88, updateColnosLists=0x0, \nwithCheckOptionLists=0x0,\n returningLists=0x0, rowMarks=0x0, onconflict=0x0, epqParam=0) at \ncreateplan.c:7007\n#3 0x0000563f035e9ab3 in create_modifytable_plan (root=0x563f05e61458, \nbest_path=0x563f05e62168) at createplan.c:2746\n#4 0x0000563f035e5936 in create_plan_recurse (root=0x563f05e61458, \nbest_path=0x563f05e62168, flags=1) at createplan.c:530\n#5 0x0000563f035e54be in create_plan (root=0x563f05e61458, \nbest_path=0x563f05e62168) at createplan.c:347\n#6 0x0000563f035f8810 in standard_planner (parse=0x563f05e60c08, \nquery_string=0x563f05ffd8d0 \"DELETE FROM test_remote WHERE \nrow(i,j)=row(new.i,new.j)\", cursorOptions=2048, \nboundParams=0x563f05e980d8) at planner.c:407\n#7 0x0000563f035f84f4 in planner (parse=0x563f05e60c08, \nquery_string=0x563f05ffd8d0 \"DELETE FROM test_remote WHERE \nrow(i,j)=row(new.i,new.j)\", cursorOptions=2048, \nboundParams=0x563f05e980d8) at planner.c:271\n#8 0x0000563f0373f9c7 in pg_plan_query (querytree=0x563f05e60c08, \nquery_string=0x563f05ffd8d0 \"DELETE FROM test_remote WHERE \nrow(i,j)=row(new.i,new.j)\", cursorOptions=2048, \nboundParams=0x563f05e980d8) at postgres.c:847\n#9 0x0000563f0373fb15 in pg_plan_queries (querytrees=0x563f05e60bb0, \nquery_string=0x563f05ffd8d0 \"DELETE FROM test_remote WHERE \nrow(i,j)=row(new.i,new.j)\", cursorOptions=2048, \nboundParams=0x563f05e980d8) at postgres.c:939\n#10 0x0000563f038dade2 in BuildCachedPlan (plansource=0x563f06027590, \nqlist=0x563f05e60bb0, boundParams=0x563f05e980d8, queryEnv=0x0) at \nplancache.c:936\n#11 0x0000563f038db4d8 in GetCachedPlan (plansource=0x563f06027590, \nboundParams=0x563f05e980d8, owner=0x563f05f6c478, queryEnv=0x0) at \nplancache.c:1218\n#12 0x0000563f03542235 in _SPI_execute_plan (plan=0x563f060c9ac0, \nparamLI=0x563f05e980d8, snapshot=0x0, crosscheck_snapshot=0x0, \nread_only=false, allow_nonatomic=false, fire_triggers=true, tcount=0, \ncaller_dest=0x0, plan_owner=0x563f05f6c478) at spi.c:2405\n#13 0x0000563f0353ebb9 in SPI_execute_plan_with_paramlist \n(plan=0x563f060c9ac0, params=0x563f05e980d8, read_only=false, tcount=0) \nat spi.c:651\n#14 0x00007f1032c2f504 in exec_stmt_execsql (estate=0x7ffcab5c6420, \nstmt=0x563f05bfb868) at pl_exec.c:4214\n#15 0x00007f1032c2a9bc in exec_stmts (estate=0x7ffcab5c6420, \nstmts=0x563f05bfb8c0) at pl_exec.c:2059\n#16 0x00007f1032c2b854 in exec_stmt_if (estate=0x7ffcab5c6420, \nstmt=0x563f06028700) at pl_exec.c:2481\n#17 0x00007f1032c2a842 in exec_stmts (estate=0x7ffcab5c6420, \nstmts=0x563f06028758) at pl_exec.c:2003\n#18 0x00007f1032c2a579 in exec_stmt_block (estate=0x7ffcab5c6420, \nblock=0x563f060288c0) at pl_exec.c:1910\n#19 0x00007f1032c29cac in exec_toplevel_block (estate=0x7ffcab5c6420, \nblock=0x563f060288c0) at pl_exec.c:1608\n#20 0x00007f1032c28730 in plpgsql_exec_trigger (func=0x563f05f6d940, \ntrigdata=0x7ffcab5c6880) at pl_exec.c:1024\n#21 0x00007f1032c43319 in plpgsql_call_handler (fcinfo=0x7ffcab5c6700) \nat pl_handler.c:268\n#22 0x0000563f034a3e2a in ExecCallTriggerFunc (trigdata=0x7ffcab5c6880, \ntgindx=0, finfo=0x563f05e7aa60, instr=0x0, \nper_tuple_context=0x563f05c763d0) at trigger.c:2141\n#23 0x0000563f034a7674 in AfterTriggerExecute (estate=0x563f05e7a2b0, \nevent=0x563f05e1a580, relInfo=0x563f05e7a738, trigdesc=0x563f05e7a950, \nfinfo=0x563f05e7aa60, instr=0x0, per_tuple_context=0x563f05c763d0, \ntrig_tuple_slot1=0x0, trig_tuple_slot2=0x0) at trigger.c:4034\n#24 0x0000563f034a7b8d in afterTriggerInvokeEvents \n(events=0x563f05f3c540, firing_id=1, estate=0x563f05e7a2b0, \ndelete_ok=false) at trigger.c:4250\n#25 0x0000563f034a8353 in AfterTriggerEndQuery (estate=0x563f05e7a2b0) \nat trigger.c:4587\n#26 0x0000563f034dc8eb in standard_ExecutorFinish \n(queryDesc=0x563f060279a0) at execMain.c:436\n#27 0x0000563f034dc7c5 in ExecutorFinish (queryDesc=0x563f060279a0) at \nexecMain.c:404\n#28 0x0000563f03745edc in ProcessQuery (plan=0x563f05fc8100, \nsourceText=0x563f05ad74a0 \"DELETE FROM test WHERE i=1;\", params=0x0, \nqueryEnv=0x0, dest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at pquery.c:190\n#29 0x0000563f037478fd in PortalRunMulti (portal=0x563f05b3aa50, \nisTopLevel=true, setHoldSnapshot=false, dest=0x563f05fc81f0, \naltdest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at pquery.c:1266\n#30 0x0000563f03746e24 in PortalRun (portal=0x563f05b3aa50, \ncount=9223372036854775807, isTopLevel=true, run_once=true, \ndest=0x563f05fc81f0, altdest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at \npquery.c:786\n#31 0x0000563f03740084 in exec_simple_query (query_string=0x563f05ad74a0 \n\"DELETE FROM test WHERE i=1;\") at postgres.c:1214\n#32 0x0000563f03744c41 in PostgresMain (argc=1, argv=0x7ffcab5c6f10, \ndbname=0x563f05b02938 \"contrib_regression\", username=0x563f05b02918 \n\"leoric\") at postgres.c:4486\n#33 0x0000563f03670f3a in BackendRun (port=0x563f05af8f00) at \npostmaster.c:4507\n#34 0x0000563f036707f3 in BackendStartup (port=0x563f05af8f00) at \npostmaster.c:4229\n#35 0x0000563f0366c97c in ServerLoop () at postmaster.c:1745\n#36 0x0000563f0366c115 in PostmasterMain (argc=8, argv=0x563f05ad1820) \nat postmaster.c:1417\n#37 0x0000563f0356193d in main (argc=8, argv=0x563f05ad1820) at \nmain.c:209\n(gdb) print *subplan\n$2 = {type = T_Result, startup_cost = 0, total_cost = 0, plan_rows = 0, \nplan_width = 0, parallel_aware = false, parallel_safe = false, \nasync_capable = false, plan_node_id = 0, targetlist = 0x563f06020d40, \nqual = 0x0, lefttree = 0x0, righttree = 0x0, initPlan = 0x0,\n extParam = 0x0, allParam = 0x0}\n\n\n-- \nBest regards,\nAlexander Pyhalov,\nPostgres Professional","msg_date":"Wed, 07 Jul 2021 17:06:14 +0300","msg_from":"Alexander Pyhalov <a.pyhalov@postgrespro.ru>","msg_from_op":true,"msg_subject":"PostgreSQL 14 backend crash on incorrect trigger"},{"msg_contents":"Alexander Pyhalov <a.pyhalov@postgrespro.ru> writes:\n> The following test case makes postgresql backend crash. The trigger is \n> incorrect, but this didn't crash postgresql before\n\nYup, that's a silly oversight. Fixed, thanks for the report!\n\n\t\t\tregards, tom lane\n\n\n","msg_date":"Wed, 07 Jul 2021 15:22:06 -0400","msg_from":"Tom Lane <tgl@sss.pgh.pa.us>","msg_from_op":false,"msg_subject":"Re: PostgreSQL 14 backend crash on incorrect trigger"}],"string":"[\n {\n \"msg_contents\": \"Hi.\\n\\nThe following test case makes postgresql backend crash. The trigger is \\nincorrect, but this didn't crash postgresql before\\n\\ncommit 86dc90056dfdbd9d1b891718d2e5614e3e432f35 (HEAD)\\nAuthor: Tom Lane <tgl@sss.pgh.pa.us>\\nDate: Wed Mar 31 11:52:34 2021 -0400\\n\\n Rework planning and execution of UPDATE and DELETE.\\n\\n\\nProgram terminated with signal SIGSEGV, Segmentation fault.\\n#0 0x00007f1032cc6905 in find_modifytable_subplan (root=0x563f05e61458, \\nplan=0x563f06020e48, rtindex=1, subplan_index=0) at postgres_fdw.c:2373\\n2373 else if (IsA(subplan, Result) && IsA(outerPlan(subplan), \\nAppend))\\n(gdb) bt\\n#0 0x00007f1032cc6905 in find_modifytable_subplan (root=0x563f05e61458, \\nplan=0x563f06020e48, rtindex=1, subplan_index=0) at postgres_fdw.c:2373\\n#1 0x00007f1032cc6a44 in postgresPlanDirectModify (root=0x563f05e61458, \\nplan=0x563f06020e48, resultRelation=1, subplan_index=0) at \\npostgres_fdw.c:2433\\n#2 0x0000563f035f2876 in make_modifytable (root=0x563f05e61458, \\nsubplan=0x563f05e626e8, operation=CMD_DELETE, canSetTag=true, \\nnominalRelation=1, rootRelation=0, partColsUpdated=false, \\nresultRelations=0x563f06020b88, updateColnosLists=0x0, \\nwithCheckOptionLists=0x0,\\n returningLists=0x0, rowMarks=0x0, onconflict=0x0, epqParam=0) at \\ncreateplan.c:7007\\n#3 0x0000563f035e9ab3 in create_modifytable_plan (root=0x563f05e61458, \\nbest_path=0x563f05e62168) at createplan.c:2746\\n#4 0x0000563f035e5936 in create_plan_recurse (root=0x563f05e61458, \\nbest_path=0x563f05e62168, flags=1) at createplan.c:530\\n#5 0x0000563f035e54be in create_plan (root=0x563f05e61458, \\nbest_path=0x563f05e62168) at createplan.c:347\\n#6 0x0000563f035f8810 in standard_planner (parse=0x563f05e60c08, \\nquery_string=0x563f05ffd8d0 \\\"DELETE FROM test_remote WHERE \\nrow(i,j)=row(new.i,new.j)\\\", cursorOptions=2048, \\nboundParams=0x563f05e980d8) at planner.c:407\\n#7 0x0000563f035f84f4 in planner (parse=0x563f05e60c08, \\nquery_string=0x563f05ffd8d0 \\\"DELETE FROM test_remote WHERE \\nrow(i,j)=row(new.i,new.j)\\\", cursorOptions=2048, \\nboundParams=0x563f05e980d8) at planner.c:271\\n#8 0x0000563f0373f9c7 in pg_plan_query (querytree=0x563f05e60c08, \\nquery_string=0x563f05ffd8d0 \\\"DELETE FROM test_remote WHERE \\nrow(i,j)=row(new.i,new.j)\\\", cursorOptions=2048, \\nboundParams=0x563f05e980d8) at postgres.c:847\\n#9 0x0000563f0373fb15 in pg_plan_queries (querytrees=0x563f05e60bb0, \\nquery_string=0x563f05ffd8d0 \\\"DELETE FROM test_remote WHERE \\nrow(i,j)=row(new.i,new.j)\\\", cursorOptions=2048, \\nboundParams=0x563f05e980d8) at postgres.c:939\\n#10 0x0000563f038dade2 in BuildCachedPlan (plansource=0x563f06027590, \\nqlist=0x563f05e60bb0, boundParams=0x563f05e980d8, queryEnv=0x0) at \\nplancache.c:936\\n#11 0x0000563f038db4d8 in GetCachedPlan (plansource=0x563f06027590, \\nboundParams=0x563f05e980d8, owner=0x563f05f6c478, queryEnv=0x0) at \\nplancache.c:1218\\n#12 0x0000563f03542235 in _SPI_execute_plan (plan=0x563f060c9ac0, \\nparamLI=0x563f05e980d8, snapshot=0x0, crosscheck_snapshot=0x0, \\nread_only=false, allow_nonatomic=false, fire_triggers=true, tcount=0, \\ncaller_dest=0x0, plan_owner=0x563f05f6c478) at spi.c:2405\\n#13 0x0000563f0353ebb9 in SPI_execute_plan_with_paramlist \\n(plan=0x563f060c9ac0, params=0x563f05e980d8, read_only=false, tcount=0) \\nat spi.c:651\\n#14 0x00007f1032c2f504 in exec_stmt_execsql (estate=0x7ffcab5c6420, \\nstmt=0x563f05bfb868) at pl_exec.c:4214\\n#15 0x00007f1032c2a9bc in exec_stmts (estate=0x7ffcab5c6420, \\nstmts=0x563f05bfb8c0) at pl_exec.c:2059\\n#16 0x00007f1032c2b854 in exec_stmt_if (estate=0x7ffcab5c6420, \\nstmt=0x563f06028700) at pl_exec.c:2481\\n#17 0x00007f1032c2a842 in exec_stmts (estate=0x7ffcab5c6420, \\nstmts=0x563f06028758) at pl_exec.c:2003\\n#18 0x00007f1032c2a579 in exec_stmt_block (estate=0x7ffcab5c6420, \\nblock=0x563f060288c0) at pl_exec.c:1910\\n#19 0x00007f1032c29cac in exec_toplevel_block (estate=0x7ffcab5c6420, \\nblock=0x563f060288c0) at pl_exec.c:1608\\n#20 0x00007f1032c28730 in plpgsql_exec_trigger (func=0x563f05f6d940, \\ntrigdata=0x7ffcab5c6880) at pl_exec.c:1024\\n#21 0x00007f1032c43319 in plpgsql_call_handler (fcinfo=0x7ffcab5c6700) \\nat pl_handler.c:268\\n#22 0x0000563f034a3e2a in ExecCallTriggerFunc (trigdata=0x7ffcab5c6880, \\ntgindx=0, finfo=0x563f05e7aa60, instr=0x0, \\nper_tuple_context=0x563f05c763d0) at trigger.c:2141\\n#23 0x0000563f034a7674 in AfterTriggerExecute (estate=0x563f05e7a2b0, \\nevent=0x563f05e1a580, relInfo=0x563f05e7a738, trigdesc=0x563f05e7a950, \\nfinfo=0x563f05e7aa60, instr=0x0, per_tuple_context=0x563f05c763d0, \\ntrig_tuple_slot1=0x0, trig_tuple_slot2=0x0) at trigger.c:4034\\n#24 0x0000563f034a7b8d in afterTriggerInvokeEvents \\n(events=0x563f05f3c540, firing_id=1, estate=0x563f05e7a2b0, \\ndelete_ok=false) at trigger.c:4250\\n#25 0x0000563f034a8353 in AfterTriggerEndQuery (estate=0x563f05e7a2b0) \\nat trigger.c:4587\\n#26 0x0000563f034dc8eb in standard_ExecutorFinish \\n(queryDesc=0x563f060279a0) at execMain.c:436\\n#27 0x0000563f034dc7c5 in ExecutorFinish (queryDesc=0x563f060279a0) at \\nexecMain.c:404\\n#28 0x0000563f03745edc in ProcessQuery (plan=0x563f05fc8100, \\nsourceText=0x563f05ad74a0 \\\"DELETE FROM test WHERE i=1;\\\", params=0x0, \\nqueryEnv=0x0, dest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at pquery.c:190\\n#29 0x0000563f037478fd in PortalRunMulti (portal=0x563f05b3aa50, \\nisTopLevel=true, setHoldSnapshot=false, dest=0x563f05fc81f0, \\naltdest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at pquery.c:1266\\n#30 0x0000563f03746e24 in PortalRun (portal=0x563f05b3aa50, \\ncount=9223372036854775807, isTopLevel=true, run_once=true, \\ndest=0x563f05fc81f0, altdest=0x563f05fc81f0, qc=0x7ffcab5c6cf0) at \\npquery.c:786\\n#31 0x0000563f03740084 in exec_simple_query (query_string=0x563f05ad74a0 \\n\\\"DELETE FROM test WHERE i=1;\\\") at postgres.c:1214\\n#32 0x0000563f03744c41 in PostgresMain (argc=1, argv=0x7ffcab5c6f10, \\ndbname=0x563f05b02938 \\\"contrib_regression\\\", username=0x563f05b02918 \\n\\\"leoric\\\") at postgres.c:4486\\n#33 0x0000563f03670f3a in BackendRun (port=0x563f05af8f00) at \\npostmaster.c:4507\\n#34 0x0000563f036707f3 in BackendStartup (port=0x563f05af8f00) at \\npostmaster.c:4229\\n#35 0x0000563f0366c97c in ServerLoop () at postmaster.c:1745\\n#36 0x0000563f0366c115 in PostmasterMain (argc=8, argv=0x563f05ad1820) \\nat postmaster.c:1417\\n#37 0x0000563f0356193d in main (argc=8, argv=0x563f05ad1820) at \\nmain.c:209\\n(gdb) print *subplan\\n$2 = {type = T_Result, startup_cost = 0, total_cost = 0, plan_rows = 0, \\nplan_width = 0, parallel_aware = false, parallel_safe = false, \\nasync_capable = false, plan_node_id = 0, targetlist = 0x563f06020d40, \\nqual = 0x0, lefttree = 0x0, righttree = 0x0, initPlan = 0x0,\\n extParam = 0x0, allParam = 0x0}\\n\\n\\n-- \\nBest regards,\\nAlexander Pyhalov,\\nPostgres Professional\",\n \"msg_date\": \"Wed, 07 Jul 2021 17:06:14 +0300\",\n \"msg_from\": \"Alexander Pyhalov <a.pyhalov@postgrespro.ru>\",\n \"msg_from_op\": true,\n \"msg_subject\": \"PostgreSQL 14 backend crash on incorrect trigger\"\n },\n {\n \"msg_contents\": \"Alexander Pyhalov <a.pyhalov@postgrespro.ru> writes:\\n> The following test case makes postgresql backend crash. The trigger is \\n> incorrect, but this didn't crash postgresql before\\n\\nYup, that's a silly oversight. Fixed, thanks for the report!\\n\\n\\t\\t\\tregards, tom lane\\n\\n\\n\",\n \"msg_date\": \"Wed, 07 Jul 2021 15:22:06 -0400\",\n \"msg_from\": \"Tom Lane <tgl@sss.pgh.pa.us>\",\n \"msg_from_op\": false,\n \"msg_subject\": \"Re: PostgreSQL 14 backend crash on incorrect trigger\"\n }\n]","isConversational":false}}}],"truncated":false,"partial":false},"paginationData":{"pageIndex":524,"numItemsPerPage":100,"numTotalItems":58371,"offset":52400,"length":100}},"jwt":"eyJhbGciOiJFZERTQSJ9.eyJyZWFkIjp0cnVlLCJwZXJtaXNzaW9ucyI6eyJyZXBvLmNvbnRlbnQucmVhZCI6dHJ1ZX0sImlhdCI6MTc4MDc3OTkyNiwic3ViIjoiL2RhdGFzZXRzL3dhbnNoZW5sL3Bnc3FsLWhhY2tlcnMiLCJleHAiOjE3ODA3ODM1MjYsImlzcyI6Imh0dHBzOi8vaHVnZ2luZ2ZhY2UuY28ifQ.BW7_zORs1GDSLRDmJqfKiP3n8tn0h-7c4wx5sCLhtc1Te8fKLDFeOsdHHmGVtu7jpM_L4uzKSrttk8o3RTZXAw","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": "Hi,\n\nPer Coverity.\n3 out-of-bounds at function AppendJumble.\n\nThey have the face, smell and color of typo.\nAnd we usually increment the character count after a memcpy.\n\nCoverity no longer complained after the patch.\n\nThoughts?\n\nregards,\nRanier Vilela",
"msg_date": "Mon, 21 Ju... |
[
{
"msg_contents": "The following generates an assertion failure. Quick testing with start \nand stop as well as the core dump shows it’s failing on the execution of \n`schema_name := schema_name(i)` immediately after COMMIT, because \nthere’s no active snapshot. On a build without asserts I get a failure \nin G... |
[
{
"msg_contents": "Hi,\n\nWhile scanning for assertion failures on the build farm that don't\nappear to have been discussed, I found this[1] in\n010_truncate_publisher.log on the 13 branch:\n\nTRAP: FailedAssertion(\"tupdesc->tdrefcount <= 0\", File:\n\"/home/bf/build/buildfarm-desmoxytes/REL_13_STABLE/pgsql.bu... |
[
{
"msg_contents": "I have accumulated a few patches to improve the output of the scripts in \nsrc/backend/utils/mb/Unicode/ to be less non-standard-looking and fix a \nfew other minor things in that area.\n\nv1-0001-Make-Unicode-makefile-more-parallel-safe.patch\n\nThe makefile rule that calls UCS_to_most.pl wa... |
[
{
"msg_contents": "Hi,\n\nHere's a curious one-off failure in test_integerset:\n\n+ERROR: iterate returned wrong value; got 519985430528, expected 485625692160\n\nhttps://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=rhinoceros&dt=2021-04-01%2018:19:47\n\n\n",
"msg_date": "Tue, 22 Jun 2021 20:53:59 +1200... |
[
{
"msg_contents": "> But making everything slower will be a hard sell, because vast majority of\r\n> workloads already running on Postgres don't have this issue at all, so\r\n> for them it's not worth the expense. Following the insurance analogy,\r\n> selling tornado insurance in Europe is mostly pointless.\r\n... |
[
{
"msg_contents": "On Mon, Jun 21, 2021 at 04:19:27PM -0700, Jim Nasby wrote:\n> The following generates an assertion failure. Quick testing with start and\n> stop as well as the core dump shows it’s failing on the execution of\n> `schema_name := schema_name(i)` immediately after COMMIT, because there’s\nno\n> ... |
[
{
"msg_contents": "I think we can benefit from higher level operator classes which can\nsupport multiple index implementations. This is achievable by\nintroducing another type of access method. Here is my idea in SQL:\n\nCREATE ACCESS METHOD ordering\nTYPE INTERFACE HANDLER ordering_ifam_handler;\n\nCREATE AC... |
[
{
"msg_contents": "When running a VACUUM or CLUSTER command, the namespace name is not part of\nthe emitted message.\n\nUsing `vacuumdb` CLI tool recently with multiple jobs, I found that\nreading the output messages harder to match the relations with their\nnamespaces.\n\nExample:\n\nINFO: vacuuming \"sendgri... |
[
{
"msg_contents": "(This is split off from my work on OAUTHBEARER [1].)\r\n\r\nCurrently, the SASL logic is tightly coupled to the SCRAM\r\nimplementation. This patch untangles the two, by introducing callback\r\nstructs for both the frontend and backend.\r\n\r\nIn the original thread, Michael Paquier commented... |
[
{
"msg_contents": "(This is split off from my work on OAUTHBEARER [1].)\r\n\r\nThe jsonapi in src/common can't currently be compiled into libpq. The\r\nfirst patch here removes the dependency on pg_log_fatal(), which is not\r\navailable to the sharedlib. The second patch makes sure that all of the\r\nreturn val... |
[
{
"msg_contents": "Hi,\n\nWhen directly INSERT INTO partition, postgres will invoke ExecPartitionCheck\nwhich will execute its parent's and grandparent's partition constraint check.\n From the code, the whole constraint check is saved in relcache::rd_partcheck.\n\nFor a multi-level partition, for example: table... |
[
{
"msg_contents": "I noticed that while inserting directly into a partition table we\ncompute the PartitionCheckExpr by traversing all the parent partitions\nvia ExecPartitionCheck()->RelationGetPartitionQual()->generate_partition_qual().\nWe take AccessShareLock on parent tables while generating qual.\n\nNow, ... |
[
{
"msg_contents": "genbki.pl says:\n\n# Perform OID lookups on an array of OID names.\n# If we don't have a unique value to substitute, warn and\n# leave the entry unchanged.\n# (A warning seems sufficient because the bootstrap backend will reject\n# non-numeric values anyway. So we might as well detect multip... |
[
{
"msg_contents": "Hi,\n\nIvan Frolkov reported a problem with choosing a non-optimal index during \na query optimization. This problem appeared after building of an \nextended statistics.\n\nI prepared the test case (see t.sql in attachment).\nFor reproduction of this case we need to have a composite primary k... |
[
{
"msg_contents": "Hi,\n\nNot per Coverity!\n\nAbout comments:\n1. For drop, no \"copy data\"\n2. Only refresh the added/*dropped* list of publications. (my emphasis)\n\nThe documentation says:\nhttps://www.postgresql.org/docs/14/sql-altersubscription.html\n\n\"DROP PUBLICATION *publication_name*\n\nChanges the... |
[
{
"msg_contents": "Hi all\r\n\r\nIn PostgreSQL 14, The default value of shared_buffers is 128MB, but in postgresql.conf.sample, the default value of shared_buffers is 32MB.\r\n\r\nI think the following changes should be made.\r\n\r\nFile: postgresql\\src\\backend\\utils\\misc\\ postgresql.conf.sample\r\n#shared... |
[
{
"msg_contents": "As many will be aware, there is a syntactic ambiguity in the SQL \nstandard regarding the keyword UNBOUNDED. Since UNBOUNDED is a \nnon-reserved word, it could be the name of a function parameter and be \nused as an expression. There is a grammar hack to resolve such cases as \nthe keyword.... |
[
{
"msg_contents": "Hi hackers,\n\nWe may have anti-joins in several cases. Sublinks of 'NOT EXISTS' may be\npulled up as anti-joins. Left joins whose join quals are strict for any\nnullable var that is forced null by higher qual levels will also be\nreduced to anti-joins. So anti-joins are very commonly used in... |
[
{
"msg_contents": "Hey,\n\nI was translating logicaldecoding.sgml, and I saw this sentence:\n\nThere are multiple required streaming callbacks\n(<function>stream_start_cb</function>, <function>stream_stop_cb</function>,\n<function>stream_abort_cb</function>, <function>stream_commit_cb</function>\nand <function>... |
[
{
"msg_contents": "COPY FREEZE throws ERRORs if you use it inappropriately. This makes it\nvery hard to use in practice.\n\nERRORs should be replaced by NOTICEs, or just silence. That treats\nFREEZE as an optional performance tweak, which is more appropriate for\nits use case.\n\nIn particular, the need to thro... |
[
{
"msg_contents": "pgbench -i should use COPY FREEZE, patch attached.\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/",
"msg_date": "Thu, 24 Jun 2021 15:03:43 +0100",
"msg_from": "Simon Riggs <simon.riggs@enterprisedb.com>",
"msg_from_op": true,
"msg_subject": "pgbench using COPY... |
[
{
"msg_contents": "Fix pattern matching logic for logs in TAP tests of pgbench\n\nThe logic checking for the format of per-thread logs used grep() with\ndirectly \"$re\", which would cause the test to consider all the logs as\na match without caring about their format at all. Using \"/$re/\" makes\ngrep() perf... |
[
{
"msg_contents": "Hi.\n\n(For brevity, in this mail I refer to \"ALTER SUBSCRIPTION sub REFRESH\nPUBLICATION\" as \"ASRP\")\n\n--\n\nThe PG Docs for ASRP WITH (copy_data = true), says \"(Previously\nsubscribed tables are not copied.)\" [1].\n\nI thought this rule meant that only tables which got added by ALTER... |
[
{
"msg_contents": "Hi all\n\nAs a result of some recent work on Windows I have a list of PGDLLIMPORTs\nI'd like to add to existing exported globals.\n\nAll affected variables are already extern, so this doesn't expose any new\nAPI not already available to non-Windows extensions.\n\nI've split the patch up for c... |
[
{
"msg_contents": "Till now, we didn't allow to stream the changes in logical replication\ntill we receive speculative confirm or the next DML change record\nafter speculative inserts. The reason was that we never use to process\nspeculative aborts but after commit 4daa140a2f it is possible to\nprocess them so ... |
[
{
"msg_contents": "Dear Hackers,\n\nI checked about DECLARE STATEMENT(added from ad8305a), and I noticed that\nthis connection-control feature cannot be used for DEALLOCATE and DESCRIBE statement.\n\nI attached the patch that fixes these bugs, this contains source and test code.\n\nHow do you think? \n\nBest Re... |
[
{
"msg_contents": "Hi all,\n\nWhile digging into some of the TAP tests, I have noticed that\n002_pgbench_no_server.pl prints array pointers, like that:\nopts=-f no-such-file, stat=1, out=ARRAY(0x1374d7990),\nerr=ARRAY(0x14028dc40), name=pgbench option error: no file# Running:\npgbench -f no-such-file\n\nI am a ... |
[
{
"msg_contents": "Hello,\n\nin src/tools/msvc/Solution.pm (in the current master) there is a \nleftover from the past:\n > confess \"Bad format of version: $self->{strver}\\n\";\n\nstrver has been gone since 8f4fb4c6 in 2019, so I suggest an obvious \none-line fix in the patch attached:\n\ndiff... |
[
{
"msg_contents": "Hello all,\n\nI am trying to add support for composite types to my ORM, which uses libpq \nand the binary format.\n\nGiven a schema like this one:\n\ncreate type composite as (...);\ncreate table sometable (field composite, ...);\n\nI want to execute a query like this:\n\nPQexecParams(\"inser... |
[
{
"msg_contents": "Hi,\n\nif a failover (or probably a switchover, at least in the way Patroni\ndoes it) occurs, the timeline history (e.g. via \"patronictl history\"[1])\nseems to read \"no recovery target specified\". That's correct, of course,\nfrom a PITR perspective, but for the (possibly more common?) pro... |
[
{
"msg_contents": "[ starting a new thread so as not to confuse the cfbot ]\n\nI wrote:\n> Michael Paquier <michael@paquier.xyz> writes:\n>> Good point. That's worse than just pfree() which is just a plain call\n>> to free() in the frontend. We could have more policies here, but my\n>> take is that we'd bette... |
[
{
"msg_contents": "Hi,\n\nI sometimes have to deal with queries referencing multiple and/or complex\nviews. In such cases, it's quite troublesome to figure out what is the query\nreally executed. Debug_print_rewritten isn't really useful for non trivial\nqueries, and manually doing the view expansion isn't gr... |
[
{
"msg_contents": "Hello all,\n\n\nI'm moving to another company from July 1st. I may possibly not be allowed to do open source activities there, so let me say goodbye once. Thank you all for your help. I really enjoyed learning PostgreSQL and participating in its development.\n\nIt's a pity that I may not b... |
[
{
"msg_contents": "> Hi,\n>\n> I sometimes have to deal with queries referencing multiple and/or complex\n> views. In such cases, it's quite troublesome to figure out what is the\n> query\n> really executed. Debug_print_rewritten isn't really useful for non trivial\n> queries, and manually doing the view expans... |
[
{
"msg_contents": "\nI am planning on forking the tree so we can start adding developments\nfor Postgres 15 in the upcoming commitfest. This will be done tomorrow,\nJune 28, late morning US East coast time. I will be following the\nprocedures laid out in src/tools/RELEASE_CHANGES under the heading\n\"Starting a... |
[
{
"msg_contents": "moonjelly just reported an interesting failure [1]. It seems that\nwith the latest bleeding-edge gcc, this code is misoptimized:\n\n /* check random range */\n if (imin > imax)\n {\n pg_log_error(\"empty range given to random\")... |
[
{
"msg_contents": "Hi,\n\nestimating joins is one of the significant gaps related to extended\nstatistics, and I've been regularly asked about what we might do about\nthat. This is an early experimental patch that I think might help us\nwith improving this, possible even in PG15.\n\nNote: I do not claim this is... |
[
{
"msg_contents": "Hello,\n\nWhile trying to use sqlsmith with postgres compiled from the master\nbranch, I've found that the PQerrorMessage() function now returns\nnon-informational but not empty error message after the successful\nPQconnectdb() call.\n conn = PQconnectdb(conninfo.c_str());\n char *errms... |
[
{
"msg_contents": "The wraparound failsafe mechanism added by commit 1e55e7d1 had minimal\ndocumentation -- just a basic description of how the GUCs work. I\nthink that it certainly merits some discussion under \"25.1. Routine\nVacuuming\" -- more specifically under \"25.1.5. Preventing Transaction\nID Wraparou... |
[
{
"msg_contents": "This is crashing repeatedly during insert/update immediately after upgrading an\ninstance to v14, from v13.3. In case it matters, the cluster was originally\ninitdb at 13.2.\n\nTRAP: FailedAssertion(\"_bt_posting_valid(nposting)\", File: \"nbtdedup.c\", Line: 1062, PID: 28580)\npostgres: tel... |
[
{
"msg_contents": "I found a couple of places where numeric multiplication suffers from\noverflow errors for inputs that aren't necessarily very large in\nmagnitude.\n\nThe first is with the numeric * operator, which attempts to always\nproduce the exact result, even though the numeric type has a maximum\nof 16... |
[
{
"msg_contents": "There are certain parts of code that laboriously initialize every field \nof a struct to (some spelling of) zero, even though the whole struct was \njust zeroed (by makeNode() or memset()) a few lines earlier. Besides \nbeing redundant, I find this hard to read in some situations because \ni... |
[
{
"msg_contents": "Here's the diff from a pgindent run. The results look kosher to me - I\nhad to do a little surgery on queryjumble.h due to it having an unused\ntypedef.\n\n\ncheers\n\n\nandrew\n\n--\nAndrew Dunstan\nEDB: https://www.enterprisedb.com",
"msg_date": "Mon, 28 Jun 2021 08:29:10 -0400",
"m... |
[
{
"msg_contents": "I happened to spot the below call in src/bin/pg_basebackup/streamutil.c which\nhas an unbounded %s in the format.\n\n /* fetch xlog value and unit from the result */\n if (sscanf(PQgetvalue(res, 0, 0), \"%d%s\", &xlog_val, xlog_unit) != 2)\n\nThere is no risk of overflow as the unit is ... |
[
{
"msg_contents": "\nThe README for pg_indent says:\n\n\n ./configure # \"make\" will not work in an unconfigured tree\n cd src/include/catalog\n make reformat-dat-files\n cd ../../..\n\n\nThis looks like a case of using a sledgehammer to crack a nut.\n\nI did this, which amounts to the same thi... |
[
{
"msg_contents": "Hi,\n\nI want to add the '--ignore-errors' option into the pg_regress module.\n\nI understand it can't be used in the regression or TAP tests. But such \noption is useful to test a custom extension. A custom extension couldn't \npass all check-world tests and will be stopped at the end of fir... |
[
{
"msg_contents": "Numeric x^y is supported for x < 0 if y is an integer, but this\ncurrently fails if y is outside the range of an int32:\n\nSELECT (-1.0) ^ 2147483647;\n ?column?\n---------------------\n -1.0000000000000000\n(1 row)\n\nSELECT (-1.0) ^ 2147483648;\nERROR: cannot take logarithm of a negat... |
[
{
"msg_contents": "Hi all,\n\nI realized that we use the magic number 10 instead of\nPG_STAT_GET_REPLICATION_SLOT_COLS in pg_stat_get_replication_slot()\nfunction. It seems an oversight of the original commit. Attached patch\nfixes it.\n\nRegards,\n\n-- \nMasahiko Sawada\nEDB: https://www.enterprisedb.com/",
... |
[
{
"msg_contents": "Hi,\n\nNot per Coverity.\n\nhash_choose_num_partitions function has issues.\nThere are at least two path calls made with used_bits = 0.\nSee at hashagg_spill_init.\n\nTo confirm, I run this code on cpp.sh:\nint main()\n{\n int npartitions = 0;\n int used_bits = 0;\n int partition_bits =... |
[
{
"msg_contents": "Hi,\n\nThe program pg_receivewal can use gzip compression to store the received WAL.\nThis patch teaches it to be able to use lz4 compression if the binary is build\nusing the -llz4 flag.\n\nPreviously, the user had to use the option --compress with a value between [0-9]\nto denote that gzip ... |
[
{
"msg_contents": "When specifying NUMERIC(precision, scale) the scale is constrained to\nthe range [0, precision], which is per SQL spec. However, at least one\nother major database vendor intentionally does not impose this\nrestriction, since allowing scales outside this range can be useful.\n\nA negative sca... |
[
{
"msg_contents": "On 2021-Jun-29, Alvaro Herrera wrote:\n\n>Ah, yes it does. I can reproduce this now. I thought PQconsumeInput\n>was sufficient, but it's not: you have to have the PQgetResult in there\n>too. Looking ...\n\nI think that has an oversight with a719232\n\nreturn false shouldn't be return 0?\n\nre... |
[
{
"msg_contents": "Hi, hackers!\n\nMany recently discussed features can make use of an extensible storage\nmanager API. Namely, storage level compression and encryption [1], [2], [3],\ndisk quota feature [4], SLRU storage changes [5], and any other features\nthat may want to substitute PostgreSQL storage layer ... |
[
{
"msg_contents": "PITR of Abort Prepared generates the wrong log message.\n\nFix attached\n\n-- \nSimon Riggs http://www.EnterpriseDB.com/",
"msg_date": "Tue, 29 Jun 2021 23:03:30 +0100",
"msg_from": "Simon Riggs <simon.riggs@enterprisedb.com>",
"msg_from_op": true,
"msg_subject"... |
[
{
"msg_contents": "Hello!\n\nTomáš Vondra has shared a few ideas to improve BRIN index in czech\nPostgreSQL mail list some time ago [1 , in czech only]. This is first\ntry to implement one of those ideas.\n\nCurrently BRIN index blocks HOT update even it is not linked tuples\ndirectly. I'm attaching the initial... |
[
{
"msg_contents": "Hi all,\n\njsonapi.c includes the following code bits to enforce the use of\nlogging:\n#ifdef FRONTEND\n#define check_stack_depth()\n#define json_log_and_abort(...) \\\n do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)\n#else\n#define json_log_and_abort(...) elog(ERROR, __VA_ARGS__)\n#en... |
[
{
"msg_contents": "For PITR, getRecordTimestamp() did not include all record types that\ncontain times.\nAdd handling for checkpoints, end of recovery and prepared xact record types.\nBased on earlier discussions with community members.\n\nAlso, allow the option of recovery_target_use_origin_time = off (default... |
[
{
"msg_contents": "Hi all,\n\nThe next commit fest is going to begin soon.\nI would like to volunteer as commit fest manager for 2021-07 if the\nrole is not filled and there are no objections.\n\nRegards,\nVignesh\n\n\n",
"msg_date": "Wed, 30 Jun 2021 19:01:03 +0530",
"msg_from": "vignesh C <vignesh21@g... |
[
{
"msg_contents": "Hi,\n\nLast year in [1], I had briefly mentioned $subject. I'm starting this\nthread to propose a small patch to alleviate the inefficiency of that\ncase.\n\nAs also mentioned in [1], when running -Mprepared benchmarks\n(plan_cache_mode = force_generic_plan) using partitioned tables,\nExecRT... |
[
{
"msg_contents": "Back when working on 959d00e9d, to allow ordered partition scans for\nLIST and RANGE partitioned tables, I mentioned [1] that if we had a\nfield that recorded a Bitmapset of the non-pruned partitions, we could\nuse that to do a more thorough check to see if ordered scans are\npossible.\n\nAt ... |
[
{
"msg_contents": "Hi.\n\nI've seen the following effect on PostgreSQL 14 stable branch.\nIndex, created on partitioned table, disappears from pg_dump or psql \\d \noutput.\nThis seems to begin after analyze. Partitoned relation relhasindex \npg_class field suddenly becomes false.\n\nThe issue happens after\n\n... |
[
{
"msg_contents": "When PostgresNode::system_or_bail() fails, it's quite opaque as to what\nis happening. This patch improves things by printing some detail, as\nsuggested in Perl's doc for system().\n\n-- \n�lvaro Herrera 39�49'30\"S 73�17'W\n htt... |
[
{
"msg_contents": "-hackers,\n\nThis patch adds the concept of \"multiconnect\" to pgbench (better\nterminology welcome). The basic idea here is to allow connections made\nwith pgbench to use different auth values or connect to multiple\ndatabases. We implement this using a user-provided PGSERVICEFILE and\ncho... |
[
{
"msg_contents": "Hello,\n\nHere is a set of patches to add SQL:2011 application-time support (aka\nvalid-time).\nPrevious discussion was on\nhttps://www.postgresql.org/message-id/20200930073908.GQ1996@paquier.xyz\nbut I thought I should update the email subject.\n\nThere are four patches here:\n\n- Add PERIOD... |
[
{
"msg_contents": "Hi,\n\nFiltering of columns at the publisher node will allow for selective\nreplication of data between publisher and subscriber. In case the updates\non the publisher are targeted only towards specific columns, the user will\nhave an option to reduce network consumption by not sending the d... |
[
{
"msg_contents": "The Core Team would like to extend our congratulations to\nDaniel Gustafsson and John Naylor, who have accepted invitations\nto become our newest Postgres committers.\n\nPlease join me in wishing them much success and few bugs.\n\n\t\t\tregards, tom lane\n\n\n",
"msg_date": "Wed, 30 Jun 2... |
[
{
"msg_contents": "(Re-sending this email, because the Commitfest app mistakenly [3]\nconsidered previous email [4] to be part of the old thread, whereas it\nshould not be considered that way)\n\nI came across this thread [1] to disallow canceling a transaction not\nyet confirmed by a synchronous replica. I thi... |
[
{
"msg_contents": "Attached is a combined diff for a set of related patches to the built-in\npgbench workloads. One commit adds an INSERT workload. One fixes the long\nstanding 0 length filler issue. A new --extra-indexes option adds the\nindexes needed for lookups added by the --foreign-keys option.\n\nThe ... |
[
{
"msg_contents": "It seems like a few too many years of an SQL standard without any\nstandardised way to LIMIT the number of records in a result set caused\nvarious applications to adopt some strange ways to get this behaviour.\nOver here in the PostgreSQL world, we just type LIMIT n; at the end of\nour querie... |
[
{
"msg_contents": "Hello.\n\nWhile I looked a patch, I found that the following ECPG statement\ngenerates uncompilable .c source.\n\nEXEC SQL CREATE TABLE t AS stmt;\n\necpgtest.c:\n#line 42 \"ecpgtest.pgc\"\n\n\t\tprintf(\"1:dbname=%s\\n\", dbname);\n\t\t{ ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_execute, create... |
[
{
"msg_contents": "Quick patch to add mention of the need for compiling with\n--enable-tap-tests on the TAP section page\n\nhttps://www.postgresql.org/docs/current/regress-tap.html\n\nSearching about the TAP tests often leads to this page, but there is no\neasy link or mention of the fact that the sample invoca... |
[
{
"msg_contents": "Hi,\n\nThe function FreePageManagerPutInternal can access an uninitialized\nvariable,\nif the following conditions occur:\n\n1. fpm->btree_depth != 0\n2. relptr_off == 0 inside function (FreePageBtreeSearch)\n\nPerhaps this is a rare situation, but I think it's worth preventing.\n\n/* Search ... |
[
{
"msg_contents": "I've recently been working with a PostgreSQL database where we saw\nReorderBufferToastReplace() fail due to a reltoastrelid value of 0. In\nthe original thread, Amit pointed out a connection to the speculative\ninsert decoding memory leak bug. Bertrand built a test case confirming\nthat a s... |
[
{
"msg_contents": "Hi,\n\nI found a strange behavior when there is an insert after renaming the\nschema. The test steps for the same are given below, Here after the\nschema is renamed, the renamed schema table data should not be sent,\nbut the data was being sent. I felt the schema invalidation was not\ncalled,... |
[
{
"msg_contents": "In my git workflow, I normally use scripts to simplify and check things.\nPreviously, most of my workfload was on master, with patches migrated to\nappropriate back branches.\n\nFYI, now that we have the release notes only in the major version\nbranches, I have had to adjust my scripts to all... |
[
{
"msg_contents": "On Fri, 2 Jul 2021 at 22:55, Dean Rasheed\n<dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:\n> Here's an update with the\n> last set of changes discussed.\nIf you allow me a small suggestion.\nMove the initializations of the variable tmp_var to after check if the\nfunction can run.\nSaves som... |
[
{
"msg_contents": "Don't try to print data type names in slot_store_error_callback().\n\nThe existing code tried to do syscache lookups in an already-failed\ntransaction, which is problematic to say the least. After some\nconsideration of alternatives, the best fix seems to be to just drop\ntype names from the... |
[
{
"msg_contents": "I've done a experimental tool to convert bison grammars to a kind of \nEBNF understood byhttps://www.bottlecaps.de/rr/ui \n<https://www.bottlecaps.de/rr/ui>to generate railroad diagrams see \nbellow the converted'postgresql-13.3/src/backend/parser/gram.y' and with \nsome hand made changes to ... |
[
{
"msg_contents": "Hi,\nI was looking at :\nRelax transactional restrictions on ALTER TYPE ... ADD VALUE (redux).\n\nIn check_safe_enum_use():\n\n+ if (!TransactionIdIsInProgress(xmin) &&\n+ TransactionIdDidCommit(xmin))\n+ return;\n\nSince the condition would be true only when TransactionIdDidCom... |
[
{
"msg_contents": "Here https://gist.github.com/mingodad/49291e0e9505522c66fcd3fcea4a939d I \nposted the postgresql-13.3/src/backend/parser/gram.y with positional \nreferences by named references that is supported by bison for some time now.\n\nIt was done with a custom script and some comments are missing, if ... |
[
{
"msg_contents": "Over in [1] it is demonstrated that with CLOBBER_CACHE_ALWAYS enabled,\ninitdb accounts for a full 50% of the runtime of \"make check-world\"\n(well, actually of the buildfarm cycle, which is not quite exactly\nthat but close). Since initdb certainly doesn't cost that much\nnormally, I wonde... |
[
{
"msg_contents": "As I've been poking around in this area, I find myself growing\nincreasingly annoyed at the new GUC name\n\"debug_invalidate_system_caches_always\". It is too d*mn long.\nIt's a serious pain to type in any context where you don't have\nautocomplete to help you. I've kept referring to this t... |
[
{
"msg_contents": "Hi hackers,\r\n\r\nWe recently ran into an issue where the visibility map of a relation was corrupt, running Postgres 12.4. The error we'd get when running a SELECT * from this table is:\r\n\r\ncould not access status of transaction 3704450152\r\nDETAIL: Could not open file \"pg_xact/0DCC\":... |
[
{
"msg_contents": "Hi all\r\n\r\nThe return value of function PQsendFlushRequest is 1 or 0.\r\n-------------------------------------------------------------------\r\n<para>\r\n Sends a request for the server to flush its output buffer.\r\n<synopsis>\r\nint PQsendFlushRequest(PGconn *conn);\r\n</synopsis>\r\n... |
[
{
"msg_contents": "Hi,\n\nThis is not a live bug.\nI think this is worth fixing, just for the sake of style and code\ncorrectness.\nAs a bonus, we have a reduced scope and standardized return.\n\nregards,\nRanier Vilela",
"msg_date": "Mon, 5 Jul 2021 09:40:31 -0300",
"msg_from": "Ranier Vilela <ranier.v... |
[
{
"msg_contents": "Hi\n\nI used the SetFileInformationByHandle function with the \nFILE_RENAME_FLAG_POSIX_SEMANTICS flag for the file rename function..\n\n1) The _WIN32_WINNT variable needs to be increased to 0x0A00 (Windows \n10). Fixed conflict with #undef CHECKSUM_TYPE_NONE\n\n2) The SetFileInformationByHan... |
[
{
"msg_contents": ">Please find attached a POC patch to do just that.\n\n>The switch to the single-datum tuplesort is done when there is only one\n>attribute, it is byval (to avoid having to deal with copy of the\nreferences\n>everywhere) and we are not in bound mode (to also avoid having to move\nthings\n>arou... |
[
{
"msg_contents": "While re-reading this code I found a small typo and fixed it (making\nthe comment more explicit at the same time).\n\nThanks,\nJames",
"msg_date": "Mon, 5 Jul 2021 14:54:51 -0400",
"msg_from": "James Coleman <jtc331@gmail.com>",
"msg_from_op": true,
"msg_subject": "Minor typo ... |
[
{
"msg_contents": "Hello,\n\nWhile testing the patch \"Add proper planner support for ORDER BY / DISTINCT \naggregates\" [0] I discovered the performance penalty from adding a sort node \nessentially came from not using the single-datum tuplesort optimization in \nExecSort (contrary to the sorting done in ExecA... |
[
{
"msg_contents": "Hi all,\r\n\r\n\r\nWhen I read the source code file src/backend/access/transam/xloginsert.c, I get something confused me.\r\nIn the function XLogSaveBufferForHint, the flags are always REGBUF_FORCE_IMAGE which means it is always need backups.\r\nIs it right? Why do not check the full_page_wri... |
[
{
"msg_contents": "Thank you for reply. \r\nYou are right and the PostgreSQL server writes the entire content of each disk page to WAL during the first modification of that page after a\r\ncheckpoint while data checksum is on. \r\n\r\n\r\nBut I wonder whether it is necessary or not while my file system can prot... |
[
{
"msg_contents": "Hi,\n\n\nI have noticed that postgres_fdw do not push down the CASE WHEN clauses. \nIn the following case this normal:\n\n contrib_regression=# EXPLAIN (ANALYZE, VERBOSE) SELECT (CASE WHEN\n mod(c1, 4) = 0 THEN 1 ELSE 2 END) FROM ft1;\n ... |
[
{
"msg_contents": "When reading the output of `initdb --help` I could not clearly\nunderstand what the purpose of the --sync-only option was, until I\nread the documentation of initdb.\n\n -S, --sync-only only sync data directory\n\nPerhaps the confusion was caused by the fact that sync(hronization)\... |
[
{
"msg_contents": "When reading through code for my previous patch [1] I realized that\ninitdb does *not* warn users that it ignores all other options (except\n-D/--pgdata) if the --sync-only option is used.\n\nI'm not able to come up with an exact situation to prove this, but\nthis behaviour seems potentially ... |
[
{
"msg_contents": "Hi \r\n\r\nWhen I used COPY FROM command on windows, I found that If the line data ends with a backslash and carriage return/newlines(\\r\\n),COPY FROM mishandle the line .\r\nAs a result, there were unexpected data loaded into database.\r\n\r\nThe following case can reproduce this issue.\r\n... |
[
{
"msg_contents": "Hi all,\n\nIndex vacuuming is one of the most time-consuming processes in lazy\nvacuuming. lazy_tid_reaped() is a large part among them. The attached\nthe flame graph shows a profile of a vacuum on a table that has one index\nand 80 million live rows and 20 million dead rows, where\nlazy_tid_... |
[
{
"msg_contents": ">You can check the more details in the attached patch. Any feedback is\nwelcome.\n\nI have tiny comments about your patch:\n\n1. name of file is uniquekey.c?\n\n+ * pathkeys.c\n+ * Utilities for maintaining uniquekey.\n\n2. Variable \"PathKey *pathkey\" at function: add_uniquekey_for_uniquei... |
[
{
"msg_contents": "Hi, hackers\n\nThe documentation [1] says:\n\nWhen dropping a subscription that is associated with a replication slot on the\nremote host (the normal state), DROP SUBSCRIPTION will connect to the remote\nhost and try to drop the replication slot as part of its operation. This is\nnecessary so... |
[
{
"msg_contents": "Hi.\n\nThe following test case makes postgresql backend crash. The trigger is \nincorrect, but this didn't crash postgresql before\n\ncommit 86dc90056dfdbd9d1b891718d2e5614e3e432f35 (HEAD)\nAuthor: Tom Lane <tgl@sss.pgh.pa.us>\nDate: Wed Mar 31 11:52:34 2021 -0400\n\n Rework planning an... |
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