diff --git "a/pgsql-performance.200405" "b/pgsql-performance.200405" new file mode 100644--- /dev/null +++ "b/pgsql-performance.200405" @@ -0,0 +1,22361 @@ +From pgsql-performance-owner@postgresql.org Fri Apr 30 22:21:18 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 9739CD1EA2A + for ; + Fri, 30 Apr 2004 22:21:17 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 20110-09 + for ; + Fri, 30 Apr 2004 22:20:59 -0300 (ADT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id AFA21D1E809 + for ; + Fri, 30 Apr 2004 22:20:55 -0300 (ADT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i411JdhO008882; + Fri, 30 Apr 2004 21:19:39 -0400 (EDT) +To: Manfred Koizar +Cc: Jochem van Dieten , + pgsql-performance@postgresql.org +Subject: Re: planner/optimizer question +In-reply-to: +References: + <409290F0.10509@oli.tudelft.nl> + +Comments: In-reply-to Manfred Koizar + message dated "Fri, 30 Apr 2004 23:36:58 +0200" +Date: Fri, 30 Apr 2004 21:19:39 -0400 +Message-ID: <8881.1083374379@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200404/531 +X-Sequence-Number: 6831 + +Manfred Koizar writes: +> Yes, the visible-to-all flag would be set as a by-product of an index +> scan, if the heap tuple is found to be visible to all active +> transactions. This update is non-critical + +Oh really? I think you need to think harder about the transition +conditions. + +Dead-to-all is reasonably safe to treat as a hint bit because *it does +not ever need to be undone*. Visible-to-all does not have that +property. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Sat May 1 00:05:00 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id C4FCED1D903 + for ; + Sat, 1 May 2004 00:04:58 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 45543-03 + for ; + Sat, 1 May 2004 00:04:38 -0300 (ADT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id D88E7D1DB23 + for ; + Sat, 1 May 2004 00:04:37 -0300 (ADT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i4134bQZ009782; + Fri, 30 Apr 2004 23:04:37 -0400 (EDT) +To: Joseph Shraibman +Cc: pgsql-performance@postgresql.org +Subject: Re: Insert only tables and vacuum performance +In-reply-to: <4091EAD8.4020503@selectacast.net> +References: <20619.1083299426@sss.pgh.pa.us> + <4091EAD8.4020503@selectacast.net> +Comments: In-reply-to Joseph Shraibman + message dated "Fri, 30 Apr 2004 01:57:44 -0400" +Date: Fri, 30 Apr 2004 23:04:36 -0400 +Message-ID: <9781.1083380676@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/1 +X-Sequence-Number: 6832 + +Joseph Shraibman writes: +> INFO: "elog": found 0 removable, 12869411 nonremovable row versions in +> 196195 pages +> DETAIL: 0 dead row versions cannot be removed yet. +> There were 5 unused item pointers. +> 0 pages are entirely empty. +> CPU 31.61s/4.53u sec elapsed 1096.83 sec. + +Hmm. These numbers suggest that your disk subsystem's bandwidth is +only about 1.4 Mbytes/sec. Was there a lot else going on? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Sat May 1 01:04:22 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 3FF56D1E742 + for ; + Sat, 1 May 2004 01:04:19 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 55393-07 + for ; + Sat, 1 May 2004 01:03:56 -0300 (ADT) +Received: from srvr3.iniquinet.com (srvr2.iniquinet.com [64.240.87.12]) + by svr1.postgresql.org (Postfix) with SMTP id 6FD0ED1E9A7 + for ; + Sat, 1 May 2004 01:03:55 -0300 (ADT) +Received: (qmail 1693 invoked by uid 104); 1 May 2004 04:03:54 -0000 +Received: from Robert_Creager@LogicalChaos.org by srvr3.iniquinet.com by uid + 101 with qmail-scanner-1.15 + (clamscan: 0.65. spamassassin: 2.55. Clear:SA:0(-7.8/6.0):. + Processed in 33.509929 secs); 01 May 2004 04:03:54 -0000 +Received: from unknown (HELO thunder.mshome.net) (216.58.165.126) + by srvr3.iniquinet.com with SMTP; 1 May 2004 04:03:20 -0000 +Received: from localhost.localdomain (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with ESMTP id 964A6BEB22; + Fri, 30 Apr 2004 22:03:19 -0600 (MDT) +Received: from logicalchaos.org (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with SMTP id AF252A7127; + Fri, 30 Apr 2004 22:03:14 -0600 (MDT) +Date: Fri, 30 Apr 2004 22:03:06 -0600 +From: Robert Creager +To: josh@agliodbs.com +Cc: pg@fastcrypt.com, =?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= , + ohp@pyrenet.fr, Tom Lane , + Joe Conway , "scott.marlowe" , + Bruce Momjian , + pgsql-performance@postgresql.org, Neil Conway +Subject: Re: Wierd context-switching issue on Xeon +Message-Id: <20040430220306.15d95162@thunder.mshome.net> +In-Reply-To: <200404291121.51247.josh@agliodbs.com> +References: + <200404211029.43675.josh@agliodbs.com> + <20040428185753.56614b2c@thunder.mshome.net> + <200404291121.51247.josh@agliodbs.com> +Organization: Starlight Vision, LLC. +X-Mailer: Sylpheed version 0.9.9claws (GTK+ 1.2.10; i586-mandrake-linux-gnu) +Mime-Version: 1.0 +Content-Type: multipart/signed; protocol="application/pgp-signature"; + micalg="pgp-sha1"; + boundary="Signature=_Fri__30_Apr_2004_22_03_06_-0600_RXm1RM=b.Jr9ZgXN" +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/2 +X-Sequence-Number: 6833 + +--Signature=_Fri__30_Apr_2004_22_03_06_-0600_RXm1RM=b.Jr9ZgXN +Content-Type: text/plain; charset=US-ASCII +Content-Disposition: inline +Content-Transfer-Encoding: 7bit + +When grilled further on (Thu, 29 Apr 2004 11:21:51 -0700), +Josh Berkus confessed: + +> spins_per_delay was not beneficial. Instead, try increasing them, one step +> at a time: +> +> (take baseline measurement at 100) +> 250 +> 500 +> 1000 +> 1500 +> 2000 +> 3000 +> 5000 +> +> ... until you find an optimal level. Then report the results to us! +> + +Some results. The patch mentioned is what Dave Cramer posted to the Performance +list on 4/21. + +A Perl script monitored for 120 seconds and generated max and average +values. Unfortunately, I am not present on site, so I cannot physically change +the device under test to increase the db load to where it hit about 10 days ago. + That will have to wait till the 'real' work week on Monday. + +Context switches - avg max + +Default 7.4.1 code : 10665 69470 +Default patch - 10 : 17297 21929 +patch at 100 : 26825 87073 +patch at 1000 : 37580 110849 + +Now granted, the db isn't showing the CS swap problem in a bad way (at all), but +should the numbers be trending the way they are with the patched code? Or will +these numbers potentially change dramatically when I can load up the db? + +And, presuming I can re-produce what I was seeing previously (200K CS/s), you +folks want me to carry on with more testing of the patch and report the results? + Or just go away and be quiet... + +The information is provided from a HP Proliant DL380 G3 with 2x 2.4 GHZ Xenon's +(with HT enabled) 2 GB ram, running 2.4.22-26mdkenterprise kernel, RAID +controller w/128 Mb battery backed cache RAID 1 on 2x 15K RPM drives for WAL +drive, RAID 0+1 on 4x 10K RPM drives for data. The only job this box has is +running this db. + +Cheers, +Rob + +-- + 21:54:48 up 2 days, 4:39, 4 users, load average: 2.00, 2.03, 2.00 +Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004 + +--Signature=_Fri__30_Apr_2004_22_03_06_-0600_RXm1RM=b.Jr9ZgXN +Content-Type: application/pgp-signature + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.4 (GNU/Linux) + +iEYEARECAAYFAkCTIYIACgkQLQ/DKuwDYznV/QCeL44IR73RUWzel6O2AhwB7x7j +fmgAnixe2lVZA9kajkXAKeTdaqzm5NtF +=jjsJ +-----END PGP SIGNATURE----- + +--Signature=_Fri__30_Apr_2004_22_03_06_-0600_RXm1RM=b.Jr9ZgXN-- + + +From pgsql-performance-owner@postgresql.org Sat May 1 08:18:25 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id E7EB7D1D35F + for ; + Sat, 1 May 2004 08:18:23 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 61763-06 + for ; + Sat, 1 May 2004 08:18:05 -0300 (ADT) +Received: from mailhost2.tudelft.nl (mailhost2.tudelft.nl [130.161.180.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 688BBD1DB23 + for ; + Sat, 1 May 2004 08:18:02 -0300 (ADT) +Received: from localhost (localhost [127.0.0.1]) + by rav.antivirus (Postfix) with ESMTP + id 184CC186DC; Sat, 1 May 2004 13:18:05 +0200 (MEST) +Received: from listserv.tudelft.nl (listserv.tudelft.nl [130.161.180.33]) + by mailhost2.tudelft.nl (Postfix) with ESMTP + id EA9C1186CD; Sat, 1 May 2004 13:18:04 +0200 (MEST) +Received: from oli.tudelft.nl (jochemd.tnw-s.tudelft.nl [145.94.90.156]) + by listserv.tudelft.nl (8.12.10/8.12.8) with ESMTP id i41BI4F7007684; + Sat, 1 May 2004 13:18:04 +0200 (MEST) +Message-ID: <4093876C.2060409@oli.tudelft.nl> +Date: Sat, 01 May 2004 13:18:04 +0200 +From: Jochem van Dieten +Organization: OnLine Internet +User-Agent: Mozilla Thunderbird 0.5 (Windows/20040207) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane +Cc: Manfred Koizar , pgsql-performance@postgresql.org +Subject: Re: planner/optimizer question +References: + <409290F0.10509@oli.tudelft.nl> + + <8881.1083374379@sss.pgh.pa.us> +In-Reply-To: <8881.1083374379@sss.pgh.pa.us> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at tudelft.nl +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/3 +X-Sequence-Number: 6834 + +Tom Lane wrote: +> Manfred Koizar writes: +>> +>> Yes, the visible-to-all flag would be set as a by-product of an index +>> scan, if the heap tuple is found to be visible to all active +>> transactions. This update is non-critical +> +> Oh really? I think you need to think harder about the transition +> conditions. +> +> Dead-to-all is reasonably safe to treat as a hint bit because *it does +> not ever need to be undone*. Visible-to-all does not have that +> property. + +Yes, really :-) + +When a tuple is inserted the visible-to-all flag is set to false. +The effect of this is that every index scan that finds this tuple +has to visit the heap to verify visibility. If it turns out the +tuple is not only visible to the current transaction, but to all +current transactions, the visible-to-all flag can be set to true. +This is non-critical, because if it is set to false scans will +not miss the tuple, they will just visit the heap to verify +visibility. + +The moment the heap tuple is updated/deleted the visible-to-all +flag needs to be set to false again in all indexes. This is +critical, and the I/O and (dead)lock costs of unsetting the +visible-to-all flag are unknown and might be big enough to ofset +any advantage on the selects. + +But I believe that for applications with a "load, select, drop" +usage pattern (warehouses, archives etc.) having this +visible-to-all flag would be a clear winner. + +Jochem + +-- +I don't get it +immigrants don't work +and steal our jobs + - Loesje + + +From pgsql-performance-owner@postgresql.org Sat May 1 09:48:49 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 97D6BD1CCDA + for ; + Sat, 1 May 2004 09:48:48 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 79966-06 + for ; + Sat, 1 May 2004 09:48:30 -0300 (ADT) +Received: from gpdnet.co.uk (gpdnet.plus.com [212.56.100.243]) + by svr1.postgresql.org (Postfix) with ESMTP id B7944D1EAEE + for ; + Sat, 1 May 2004 09:48:25 -0300 (ADT) +Received: from gary (unverified [192.168.1.2]) + by gpdnet.co.uk (SurgeMail 1.8g3) with ESMTP id 143 + for ; Sat, 01 May 2004 13:47:41 +0100 +From: "Gary Doades" +To: pgsql-performance@postgresql.org +Date: Sat, 01 May 2004 13:48:35 +0100 +MIME-Version: 1.0 +Subject: Re: planner/optimizer question +Message-ID: <4093AAB3.21370.742972@localhost> +In-reply-to: <4093876C.2060409@oli.tudelft.nl> +References: <8881.1083374379@sss.pgh.pa.us> +X-mailer: Pegasus Mail for Windows (v4.12a) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Server: High Performance Mail Server - http://surgemail.com +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/4 +X-Sequence-Number: 6835 + +On 1 May 2004 at 13:18, Jochem van Dieten wrote: + +> Yes, really :-) +> +> When a tuple is inserted the visible-to-all flag is set to false. +> The effect of this is that every index scan that finds this tuple +> has to visit the heap to verify visibility. If it turns out the +> tuple is not only visible to the current transaction, but to all +> current transactions, the visible-to-all flag can be set to true. +> This is non-critical, because if it is set to false scans will +> not miss the tuple, they will just visit the heap to verify +> visibility. +> +> The moment the heap tuple is updated/deleted the visible-to-all +> flag needs to be set to false again in all indexes. This is +> critical, and the I/O and (dead)lock costs of unsetting the +> visible-to-all flag are unknown and might be big enough to ofset +> any advantage on the selects. +> +> But I believe that for applications with a "load, select, drop" +> usage pattern (warehouses, archives etc.) having this +> visible-to-all flag would be a clear winner. +> +> Jochem +> + +If needs be this index maintenance could be set as a configuration +option. It is likely that database usage patterns are reasonably well +known for a particular installation. This option could be set on or off +dependant on typical transactions. + +In my case with frequent large/complex selects and few very short +insert/updates I think it could be a big performance boost. If it works :-) + +Regards, +Gary. + + +From pgsql-performance-owner@postgresql.org Sat May 1 13:23:08 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id BB76DD1EB24 + for ; + Sat, 1 May 2004 13:23:07 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 27122-10 + for ; + Sat, 1 May 2004 13:22:46 -0300 (ADT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 4B3B8D1EAC6 + for ; + Sat, 1 May 2004 13:22:45 -0300 (ADT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i41GLS6g014615; + Sat, 1 May 2004 12:21:28 -0400 (EDT) +To: Jochem van Dieten +Cc: Manfred Koizar , pgsql-performance@postgresql.org +Subject: Re: planner/optimizer question +In-reply-to: <4093876C.2060409@oli.tudelft.nl> +References: + <409290F0.10509@oli.tudelft.nl> + + <8881.1083374379@sss.pgh.pa.us> <4093876C.2060409@oli.tudelft.nl> +Comments: In-reply-to Jochem van Dieten + message dated "Sat, 01 May 2004 13:18:04 +0200" +Date: Sat, 01 May 2004 12:21:28 -0400 +Message-ID: <14614.1083428488@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/5 +X-Sequence-Number: 6836 + +Jochem van Dieten writes: +> The moment the heap tuple is updated/deleted the visible-to-all +> flag needs to be set to false again in all indexes. This is +> critical, + +Exactly. This gets you out of the hint-bit semantics and into a ton +of interesting problems, such as race conditions. (Process A determines +that tuple X is visible-to-all, and goes to update the index tuple. +Before it can reacquire lock on the index page, process B updates the +heap tuple and visits the index to clear the flag bit. Once A obtains +lock it will set the flag bit. Oops.) + +Basically what you are buying into with such a thing is multiple copies +of critical state. It may be only one bit rather than several words, +but updating it is no less painful than if it were a full copy of the +tuple's commit status. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Sat May 1 15:51:19 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id E7653D1EB4C + for ; + Sat, 1 May 2004 15:51:18 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 57849-10 + for ; + Sat, 1 May 2004 15:50:59 -0300 (ADT) +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 6C268D1B432 + for ; + Sat, 1 May 2004 15:50:57 -0300 (ADT) +Received: (qmail 3372 invoked from network); 1 May 2004 18:50:49 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.36?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 1 May 2004 18:50:49 -0000 +Subject: Re: Wierd context-switching issue on Xeon +From: Dave Cramer +Reply-To: pg@fastcrypt.com +To: Robert Creager +Cc: Josh Berkus , + =?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= , + ohp@pyrenet.fr, Tom Lane , + Joe Conway , "scott.marlowe" , + Bruce Momjian , + pgsql-performance@postgresql.org, Neil Conway +In-Reply-To: <20040430220306.15d95162@thunder.mshome.net> +References: + <200404211029.43675.josh@agliodbs.com> + <20040428185753.56614b2c@thunder.mshome.net> + <200404291121.51247.josh@agliodbs.com> + <20040430220306.15d95162@thunder.mshome.net> +Content-Type: text/plain +Organization: Cramer Consulting +Message-Id: <1083437446.25697.109.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 +Date: Sat, 01 May 2004 14:50:47 -0400 +Content-Transfer-Encoding: 7bit +X-AntiVirus: scanned for viruses by AMaViS 0.2.1 (http://amavis.org/) +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/6 +X-Sequence-Number: 6837 + +No, don't go away and be quiet. Keep testing, it may be that under +normal operation the context switching goes up but under the conditions +that you were seeing the high CS it may not be as bad. + +As others have mentioned the real solution to this is to rewrite the +buffer management so that the lock isn't quite as coarse grained. + +Dave +On Sat, 2004-05-01 at 00:03, Robert Creager wrote: +> When grilled further on (Thu, 29 Apr 2004 11:21:51 -0700), +> Josh Berkus confessed: +> +> > spins_per_delay was not beneficial. Instead, try increasing them, one step +> > at a time: +> > +> > (take baseline measurement at 100) +> > 250 +> > 500 +> > 1000 +> > 1500 +> > 2000 +> > 3000 +> > 5000 +> > +> > ... until you find an optimal level. Then report the results to us! +> > +> +> Some results. The patch mentioned is what Dave Cramer posted to the Performance +> list on 4/21. +> +> A Perl script monitored for 120 seconds and generated max and average +> values. Unfortunately, I am not present on site, so I cannot physically change +> the device under test to increase the db load to where it hit about 10 days ago. +> That will have to wait till the 'real' work week on Monday. +> +> Context switches - avg max +> +> Default 7.4.1 code : 10665 69470 +> Default patch - 10 : 17297 21929 +> patch at 100 : 26825 87073 +> patch at 1000 : 37580 110849 +> +> Now granted, the db isn't showing the CS swap problem in a bad way (at all), but +> should the numbers be trending the way they are with the patched code? Or will +> these numbers potentially change dramatically when I can load up the db? +> +> And, presuming I can re-produce what I was seeing previously (200K CS/s), you +> folks want me to carry on with more testing of the patch and report the results? +> Or just go away and be quiet... +> +> The information is provided from a HP Proliant DL380 G3 with 2x 2.4 GHZ Xenon's +> (with HT enabled) 2 GB ram, running 2.4.22-26mdkenterprise kernel, RAID +> controller w/128 Mb battery backed cache RAID 1 on 2x 15K RPM drives for WAL +> drive, RAID 0+1 on 4x 10K RPM drives for data. The only job this box has is +> running this db. +> +> Cheers, +> Rob +-- +Dave Cramer +519 939 0336 +ICQ # 14675561 + + +From pgsql-performance-owner@postgresql.org Sun May 2 05:01:20 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 3DD82D1ED94 + for ; + Sun, 2 May 2004 05:01:19 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 26054-09 + for ; + Sun, 2 May 2004 05:01:00 -0300 (ADT) +Received: from email06.aon.at (WARSL402PIP3.highway.telekom.at [195.3.96.75]) + by svr1.postgresql.org (Postfix) with SMTP id C010ED1ED84 + for ; + Sun, 2 May 2004 05:00:57 -0300 (ADT) +Received: (qmail 450502 invoked from network); 2 May 2004 08:00:57 -0000 +Received: from m167p018.dipool.highway.telekom.at (HELO PASCAL) + ([62.46.10.210]) (envelope-sender ) + by qmail6rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 2 May 2004 08:00:57 -0000 +From: Manfred Koizar +To: Jochem van Dieten +Cc: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: planner/optimizer question +Date: Sun, 02 May 2004 10:03:36 +0200 +Message-ID: +References: + <409290F0.10509@oli.tudelft.nl> + + <8881.1083374379@sss.pgh.pa.us> <4093876C.2060409@oli.tudelft.nl> +In-Reply-To: <4093876C.2060409@oli.tudelft.nl> +X-Mailer: Forte Agent 2.0/32.652 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.1 tagged_above=0.0 required=5.0 tests=RCVD_IN_SORBS +X-Spam-Level: +X-Archive-Number: 200405/7 +X-Sequence-Number: 6838 + +On Sat, 01 May 2004 13:18:04 +0200, Jochem van Dieten + wrote: +>Tom Lane wrote: +>> Oh really? I think you need to think harder about the transition +>> conditions. + +Indeed. + +>> +>> Dead-to-all is reasonably safe to treat as a hint bit because *it does +>> not ever need to be undone*. Visible-to-all does not have that +>> property. +> +>Yes, really :-) + +No, not really :-( + +As Tom has explained in a nearby message his concern is that -- unlike +dead-to-all -- visible-to-all starts as false, is set to true at some +point in time, and is eventually set to false again. Problems arise if +one backend wants to set visible-to-all to true while at the same time +another backend wants to set it to false. + +This could be curable by using a second bit as a deleted flag (might be +even the same bit that's now used as dead-to-all, but I'm not sure). An +index tuple having both the visible flag (formerly called +visible-to-all) and the deleted flag set would cause a heap tuple access +to check visibility. But that leaves the question of what to do after +the deleting transaction has rolled back. I see no clean way from the +visible-and-deleted state to visible-to-all. + +This obviously needs another round of hard thinking ... + + +From pgsql-performance-owner@postgresql.org Sun May 2 05:10:26 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id DB308D1B432 + for ; + Sun, 2 May 2004 05:10:23 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 38484-04 + for ; + Sun, 2 May 2004 05:10:03 -0300 (ADT) +Received: from roam.unifiedmind.com (unifiedmind.com [209.164.72.58]) + by svr1.postgresql.org (Postfix) with SMTP id 12BCFD1C4C4 + for ; + Sun, 2 May 2004 05:10:01 -0300 (ADT) +Received: (qmail 20259 invoked from network); 2 May 2004 08:31:20 -0000 +Received: from unknown (HELO jamesthornton.com) (james@69.150.60.163) + by 0 with SMTP; 2 May 2004 08:31:20 -0000 +Message-ID: <4094AD20.6090707@jamesthornton.com> +Date: Sun, 02 May 2004 03:11:12 -0500 +From: James Thornton +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.4) Gecko/20030624 Netscape/7.1 (ax) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Recommended File System Configuration +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/8 +X-Sequence-Number: 6839 + +Back in 2001, there was a lengthy thread on the PG Hackers list about PG +and journaling file systems +(http://archives.postgresql.org/pgsql-hackers/2001-05/msg00017.php), but +there was no decisive conclusion regarding what FS to use. At the time +the fly in the XFS ointment was that deletes were slow, but this was +improved with XFS 1.1. + +I think a journaling a FS is needed for PG data since large DBs could +take hours to recover on a non-journaling FS, but what about WAL files? + +-- + + James Thornton +______________________________________________________ +Internet Business Consultant, http://jamesthornton.com + + + +From pgsql-performance-owner@postgresql.org Sun May 2 11:31:05 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 8497AD1E9CA + for ; + Sun, 2 May 2004 11:31:04 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 16942-09 + for ; + Sun, 2 May 2004 11:30:47 -0300 (ADT) +Received: from mailhost2.tudelft.nl (mailhost2.tudelft.nl [130.161.180.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 4DF17D1EDE3 + for ; + Sun, 2 May 2004 11:30:43 -0300 (ADT) +Received: from localhost (localhost [127.0.0.1]) + by rav.antivirus (Postfix) with ESMTP + id 827C430C84; Sun, 2 May 2004 16:30:47 +0200 (MEST) +Received: from listserv.tudelft.nl (listserv.tudelft.nl [130.161.180.33]) + by mailhost2.tudelft.nl (Postfix) with ESMTP + id 5819530C7E; Sun, 2 May 2004 16:30:47 +0200 (MEST) +Received: from oli.tudelft.nl (www@secure.oli.tudelft.nl [130.161.180.141]) + by listserv.tudelft.nl (8.12.10/8.12.8) with SMTP id i42EUkF7016249; + Sun, 2 May 2004 16:30:47 +0200 (MEST) +Received: from 130.161.199.221 + (SquirrelMail authenticated user jochemd@oli.tudelft.nl) + by secure.oli.tudelft.nl with HTTP; + Sun, 2 May 2004 16:30:47 +0200 (CEST) +Message-ID: <1529.130.161.199.221.1083508247.squirrel@secure.oli.tudelft.nl> +Date: Sun, 2 May 2004 16:30:47 +0200 (CEST) +Subject: Re: planner/optimizer question +From: "Jochem van Dieten" +To: +In-Reply-To: +References: + <409290F0.10509@oli.tudelft.nl> + + <8881.1083374379@sss.pgh.pa.us> <4093876C.2060409@oli.tudelft.nl> + +X-Priority: 3 +Importance: Normal +Cc: , +X-Mailer: SquirrelMail (version 1.2.10) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Virus-Scanned: by amavisd-new at tudelft.nl +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/9 +X-Sequence-Number: 6840 + +Manfred Koizar said: +> +> As Tom has explained in a nearby message his concern is that -- +> unlike dead-to-all -- visible-to-all starts as false, is set to true +> at some point in time, and is eventually set to false again. +> Problems arise if one backend wants to set visible-to-all to true +> while at the same time another backend wants to set it to false. + +Got it, I misinterpreted his concern as "visible-to-all should not be +set to true when the tuple is inserted". + + +> This could be curable by using a second bit as a deleted flag (might +> be even the same bit that's now used as dead-to-all, but I'm not +> sure). An index tuple having both the visible flag (formerly called +> visible-to-all) and the deleted flag set would cause a heap tuple +> access to check visibility. + +Or in a more generalized way: with 2 bits written at the same time you +can express 4 states. But only 3 actions need to be signalled: +dead-to-all, visible-to-all and check-heap. So we can have 2 states +that both signal check-heap. + +The immediate solution to the race condition Tom presented would be to +have the transaction that invalidates the heap tuple switch the index +tuple from the one check-heap state to the other. The transaction that +wants to update to visible-to-all can now see that the state has +changed (but not the meaning) and aborts its change. + + +> But that leaves the question of what to +> do after the deleting transaction has rolled back. I see no clean +> way from the visible-and-deleted state to visible-to-all. + +I'm afraid I don't know enough about the inner workings of rollbacks +to determine how the scenario "A determines visible-to-all should be +set, B invalidates tuple, B rolls back, C invalidates tuple, C +commits, A reaquires lock on index" would work out. I guess I have +some more reading to do. + +But if you don't roll back too often it wouldn't even be a huge +problem to just leave them in visible-and-deleted state until +eventually they go into the dead-to-all state. + +Jochem + + + + + +From pgsql-performance-owner@postgresql.org Sun May 2 12:21:55 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 54AA3D1B432 + for ; + Sun, 2 May 2004 12:21:54 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 30354-03 + for ; + Sun, 2 May 2004 12:21:33 -0300 (ADT) +Received: from srvr3.iniquinet.com (srvr2.iniquinet.com [64.240.87.12]) + by svr1.postgresql.org (Postfix) with SMTP id E0B1FD1ED68 + for ; + Sun, 2 May 2004 12:21:32 -0300 (ADT) +Received: (qmail 28735 invoked by uid 104); 2 May 2004 15:21:31 -0000 +Received: from Robert_Creager@LogicalChaos.org by srvr3.iniquinet.com by uid + 101 with qmail-scanner-1.15 + (clamscan: 0.65. spamassassin: 2.55. Clear:SA:0(-7.6/6.0):. + Processed in 33.706185 secs); 02 May 2004 15:21:31 -0000 +Received: from unknown (HELO thunder.mshome.net) (216.58.165.126) + by srvr3.iniquinet.com with SMTP; 2 May 2004 15:20:57 -0000 +Received: from localhost.localdomain (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with ESMTP id EA9D3116911; + Sun, 2 May 2004 09:20:56 -0600 (MDT) +Received: from logicalchaos.org (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with SMTP id 3CDB3116911; + Sun, 2 May 2004 09:20:54 -0600 (MDT) +Date: Sun, 2 May 2004 09:20:47 -0600 +From: Robert Creager +To: pg@fastcrypt.com +Cc: Josh Berkus , + =?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= , + ohp@pyrenet.fr, Tom Lane , + Joe Conway , "scott.marlowe" , + Bruce Momjian , + pgsql-performance@postgresql.org, Neil Conway +Subject: Re: Wierd context-switching issue on Xeon +Message-Id: <20040502092047.029525f6@thunder.mshome.net> +In-Reply-To: <1083437446.25697.109.camel@localhost.localdomain> +References: + <200404211029.43675.josh@agliodbs.com> + <20040428185753.56614b2c@thunder.mshome.net> + <200404291121.51247.josh@agliodbs.com> + <20040430220306.15d95162@thunder.mshome.net> + <1083437446.25697.109.camel@localhost.localdomain> +Organization: Starlight Vision, LLC. +X-Mailer: Sylpheed version 0.9.10claws (GTK+ 1.2.10; i586-mandrake-linux-gnu) +Mime-Version: 1.0 +Content-Type: multipart/signed; protocol="application/pgp-signature"; + micalg="pgp-sha1"; + boundary="Signature=_Sun__2_May_2004_09_20_47_-0600_X.5Ymos/ukZSWEQz" +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/10 +X-Sequence-Number: 6841 + +--Signature=_Sun__2_May_2004_09_20_47_-0600_X.5Ymos/ukZSWEQz +Content-Type: text/plain; charset=US-ASCII +Content-Disposition: inline +Content-Transfer-Encoding: 7bit + + +Found some co-workers at work yesterday to load up my library... + +The sample period is 5 minutes long (vs 2 minutes previously): + +Context switches - avg max + +Default 7.4.1 code : 48784 107354 +Default patch - 10 : 20400 28160 +patch at 100 : 38574 85372 +patch at 1000 : 41188 106569 + +The reading at 1000 was not produced under the same circumstances as the prior +readings as I had to replace my device under test with a simulated one. The +real one died. + +The previous run with smaller database and 120 second averages: + +Context switches - avg max + +Default 7.4.1 code : 10665 69470 +Default patch - 10 : 17297 21929 +patch at 100 : 26825 87073 +patch at 1000 : 37580 110849 + +-- + 20:13:50 up 3 days, 2:58, 4 users, load average: 2.12, 2.14, 2.10 +Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004 + +--Signature=_Sun__2_May_2004_09_20_47_-0600_X.5Ymos/ukZSWEQz +Content-Type: application/pgp-signature + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.4 (GNU/Linux) + +iEYEARECAAYFAkCVEdYACgkQLQ/DKuwDYzk2rQCeNztby++bxLqjgCCSTb+iar2T +i6gAn1T/hPOp4vOQ/GssEjHYTOZMYjQu +=qu7E +-----END PGP SIGNATURE----- + +--Signature=_Sun__2_May_2004_09_20_47_-0600_X.5Ymos/ukZSWEQz-- + + +From pgsql-performance-owner@postgresql.org Sun May 2 12:39:55 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E80CD1B432 + for ; + Sun, 2 May 2004 12:39:54 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 34519-06 + for ; + Sun, 2 May 2004 12:39:34 -0300 (ADT) +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id C1553D1E123 + for ; + Sun, 2 May 2004 12:39:33 -0300 (ADT) +Received: (qmail 31037 invoked from network); 2 May 2004 15:39:24 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.36?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 2 May 2004 15:39:24 -0000 +Subject: Re: Wierd context-switching issue on Xeon +From: Dave Cramer +Reply-To: pg@fastcrypt.com +To: Robert Creager +Cc: Josh Berkus , + =?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= , + ohp@pyrenet.fr, Tom Lane , + Joe Conway , "scott.marlowe" , + Bruce Momjian , + pgsql-performance@postgresql.org, Neil Conway +In-Reply-To: <20040502092047.029525f6@thunder.mshome.net> +References: + <200404211029.43675.josh@agliodbs.com> + <20040428185753.56614b2c@thunder.mshome.net> + <200404291121.51247.josh@agliodbs.com> + <20040430220306.15d95162@thunder.mshome.net> + <1083437446.25697.109.camel@localhost.localdomain> + <20040502092047.029525f6@thunder.mshome.net> +Content-Type: text/plain +Organization: Cramer Consulting +Message-Id: <1083512362.25096.131.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 +Date: Sun, 02 May 2004 11:39:22 -0400 +Content-Transfer-Encoding: 7bit +X-AntiVirus: scanned for viruses by AMaViS 0.2.1 (http://amavis.org/) +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/11 +X-Sequence-Number: 6842 + +Robert, + +The real question is does it help under real life circumstances ? + +Did you do the tests with Tom's sql code that is designed to create high +context switchs ? + +Dave +On Sun, 2004-05-02 at 11:20, Robert Creager wrote: +> Found some co-workers at work yesterday to load up my library... +> +> The sample period is 5 minutes long (vs 2 minutes previously): +> +> Context switches - avg max +> +> Default 7.4.1 code : 48784 107354 +> Default patch - 10 : 20400 28160 +> patch at 100 : 38574 85372 +> patch at 1000 : 41188 106569 +> +> The reading at 1000 was not produced under the same circumstances as the prior +> readings as I had to replace my device under test with a simulated one. The +> real one died. +> +> The previous run with smaller database and 120 second averages: +> +> Context switches - avg max +> +> Default 7.4.1 code : 10665 69470 +> Default patch - 10 : 17297 21929 +> patch at 100 : 26825 87073 +> patch at 1000 : 37580 110849 +-- +Dave Cramer +519 939 0336 +ICQ # 14675561 + + +From pgsql-performance-owner@postgresql.org Sun May 2 18:47:49 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 33AF0D1EE01 + for ; + Sun, 2 May 2004 18:47:47 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 17226-09 + for ; + Sun, 2 May 2004 18:47:28 -0300 (ADT) +Received: from srvr3.iniquinet.com (srvr2.iniquinet.com [64.240.87.12]) + by svr1.postgresql.org (Postfix) with SMTP id 3C6DFD1EDF9 + for ; + Sun, 2 May 2004 18:47:25 -0300 (ADT) +Received: (qmail 24698 invoked by uid 104); 2 May 2004 21:47:26 -0000 +Received: from Robert_Creager@LogicalChaos.org by srvr3.iniquinet.com by uid + 101 with qmail-scanner-1.15 + (clamscan: 0.65. spamassassin: 2.55. Clear:SA:0(-7.8/6.0):. + Processed in 33.66656 secs); 02 May 2004 21:47:26 -0000 +Received: from unknown (HELO thunder.mshome.net) (216.58.165.126) + by srvr3.iniquinet.com with SMTP; 2 May 2004 21:46:52 -0000 +Received: from localhost.localdomain (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with ESMTP id 5769FB90A0; + Sun, 2 May 2004 15:46:52 -0600 (MDT) +Received: from logicalchaos.org (thunder.mshome.net [192.168.0.250]) + by thunder.mshome.net (Postfix) with SMTP id A52F8B90A0; + Sun, 2 May 2004 15:46:50 -0600 (MDT) +Date: Sun, 2 May 2004 15:46:49 -0600 +From: Robert Creager +To: pg@fastcrypt.com +Cc: Josh Berkus , + =?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= , + ohp@pyrenet.fr, Tom Lane , + Joe Conway , "scott.marlowe" , + Bruce Momjian , + pgsql-performance@postgresql.org, Neil Conway +Subject: Re: Wierd context-switching issue on Xeon +Message-Id: <20040502154649.3cb2f283@thunder.mshome.net> +In-Reply-To: <1083512362.25096.131.camel@localhost.localdomain> +References: + <200404211029.43675.josh@agliodbs.com> + <20040428185753.56614b2c@thunder.mshome.net> + <200404291121.51247.josh@agliodbs.com> + <20040430220306.15d95162@thunder.mshome.net> + <1083437446.25697.109.camel@localhost.localdomain> + <20040502092047.029525f6@thunder.mshome.net> + <1083512362.25096.131.camel@localhost.localdomain> +Organization: Starlight Vision, LLC. +X-Mailer: Sylpheed version 0.9.10claws (GTK+ 1.2.10; i586-mandrake-linux-gnu) +Mime-Version: 1.0 +Content-Type: multipart/signed; protocol="application/pgp-signature"; + micalg="pgp-sha1"; + boundary="Signature=_Sun__2_May_2004_15_46_49_-0600_39iKNqpvwjELTqoo" +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/12 +X-Sequence-Number: 6843 + +--Signature=_Sun__2_May_2004_15_46_49_-0600_39iKNqpvwjELTqoo +Content-Type: text/plain; charset=US-ASCII +Content-Disposition: inline +Content-Transfer-Encoding: 7bit + +When grilled further on (Sun, 02 May 2004 11:39:22 -0400), +Dave Cramer confessed: + +> Robert, +> +> The real question is does it help under real life circumstances ? + +I'm not yet at the point where the CS's are causing appreciable delays. I +should get there early this week and will be able to measure the relief your +patch may provide. + +> +> Did you do the tests with Tom's sql code that is designed to create high +> context switchs ? + +No, I'm using my queries/data. + +Cheers, +Rob + +-- + 10:44:58 up 3 days, 17:30, 4 users, load average: 2.00, 2.04, 2.01 +Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004 + +--Signature=_Sun__2_May_2004_15_46_49_-0600_39iKNqpvwjELTqoo +Content-Type: application/pgp-signature + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.4 (GNU/Linux) + +iEYEARECAAYFAkCVbEoACgkQLQ/DKuwDYzlTzQCfaBE0lZJ2oOcmYUAEPpvTMo0N +MtMAnRN/Io8B45X7/EL3lvCkzBrXbV9J +=ZVMt +-----END PGP SIGNATURE----- + +--Signature=_Sun__2_May_2004_15_46_49_-0600_39iKNqpvwjELTqoo-- + + +From pgsql-bugs-owner@postgresql.org Tue May 4 09:54:44 2004 +X-Original-To: pgsql-bugs-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 32F21D1EF8E + for ; + Mon, 3 May 2004 13:31:04 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 38650-03 + for ; + Mon, 3 May 2004 13:30:48 -0300 (ADT) +Received: from ganymede.hub.org (u46n208.hfx.eastlink.ca [24.222.46.208]) + by svr1.postgresql.org (Postfix) with ESMTP id 72638D1EF8C + for ; Mon, 3 May 2004 13:30:43 -0300 (ADT) +Received: by ganymede.hub.org (Postfix, from userid 1000) + id 641033AA01; Mon, 3 May 2004 13:30:50 -0300 (ADT) +Received: from localhost (localhost [127.0.0.1]) + by ganymede.hub.org (Postfix) with ESMTP id 592213A947 + for ; Mon, 3 May 2004 13:30:50 -0300 (ADT) +X-Received: from localhost ([unix socket]) + by ganymede.hub.org (Cyrus v2.2.3) with LMTP; + Mon, 03 May 2004 13:10:38 -0300 +X-Sieve: CMU Sieve 2.2 +X-Received: from localhost (localhost [127.0.0.1]) + by ganymede.hub.org (Postfix) with ESMTP id 734C73A64D + for ; Mon, 3 May 2004 13:10:36 -0300 (ADT) +X-Received: from mail.postgresql.org [200.46.204.71] + by localhost with IMAP (fetchmail-6.2.5) + for scrappy@localhost (single-drop); + Mon, 03 May 2004 13:10:36 -0300 (ADT) +X-Received: from svr1.postgresql.org ([unix socket]) + by svr1.postgresql.org (Cyrus v2.2.3) with LMTP; + Mon, 03 May 2004 13:08:37 -0300 +X-Sieve: CMU Sieve 2.2 +X-Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 1EEE4D1EF81 + for ; Mon, 3 May 2004 13:08:37 -0300 (ADT) +X-Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 25024-06 for ; + Mon, 3 May 2004 13:08:19 -0300 (ADT) +X-Received: from smtprelay02.ispgateway.de (smtprelay02.ispgateway.de + [62.67.200.157]) + by svr1.postgresql.org (Postfix) with ESMTP id 465D3D1EF7B + for ; Mon, 3 May 2004 13:08:13 -0300 (ADT) +X-Received: (qmail 19882 invoked from network); 3 May 2004 16:08:17 -0000 +X-Received: from unknown (HELO tcn.local) ([pbs]652696@[217.93.30.36]) + (envelope-sender ) + by smtprelay02.ispgateway.de (qmail-ldap-1.03) with AES256-SHA + encrypted SMTP + for ; 3 May 2004 16:08:17 -0000 +X-Received: from [127.0.0.1] (localhost [127.0.0.1]) + by tcn.local (Postfix) with ESMTP id 947B6AB9 + for ; Mon, 3 May 2004 18:08:23 +0200 (CEST) +Message-ID: <40966E77.4020004@nitwit.de> +Date: Mon, 03 May 2004 18:08:23 +0200 +From: Timo Nentwig +User-Agent: Mozilla Thunderbird 0.6 (X11/20040502) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: support@postgresql.org +Subject: Bug in optimizer +X-Enigmail-Version: 0.83.6.0 +X-Enigmail-Supports: pgp-inline, pgp-mime +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-DCC: : +X-Spam-Pyzor: +ReSent-Date: Mon, 3 May 2004 13:30:46 -0300 (ADT) +Resent-From: "Marc G. Fournier" +Resent-To: pgsql-bugs@postgresql.org +ReSent-Subject: Bug in optimizer +ReSent-Message-ID: <20040503133046.V22860@ganymede.hub.org> +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=1.0 tagged_above=0.0 required=5.0 tests=BIZ_TLD, + UPPERCASE_25_50 +X-Spam-Level: * +X-Archive-Number: 200405/26 +X-Sequence-Number: 8298 + +-----BEGIN PGP SIGNED MESSAGE----- +Hash: SHA1 + +Hi! + +Your bug report form on the web doesn't work. + + +This is very slow: + +SELECT urls.id FROM urls WHERE +( + urls.id <> ALL (SELECT html.urlid FROM html) +); + +...while this is quite fast: + +SELECT urls.id FROM urls WHERE +( + NOT (EXISTS (SELECT html.urlid FROM tml WHERE + ( + html.urlid = urls.id + ))) +); + +Regards +Timo +- -- +http://nentwig.biz/ (J2EE) +http://nitwit.de/ + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.2 (GNU/Linux) + +iD8DBQFAlm53cmRm71Um+e0RAkJuAKChd+6zoFesZfBY/cGRsSVagnJeswCeMD5s +++Es8hVsFlUpkIIsRfrBp4Y= +=STbS +-----END PGP SIGNATURE----- + +From pgsql-performance-owner@postgresql.org Mon May 3 14:16:13 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 535BDD1EECD + for ; + Mon, 3 May 2004 14:16:12 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 51650-08 + for ; + Mon, 3 May 2004 14:15:55 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 8C429D1EF18 + for ; + Mon, 3 May 2004 14:15:49 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.12.9/8.12.9) with ESMTP id i43HFmSx096413 + for ; Mon, 3 May 2004 17:15:48 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.12.9/8.12.9/Submit) id i43H9uRr087217 + for pgsql-performance@postgresql.org; Mon, 3 May 2004 17:09:56 GMT +From: Chris Browne +X-Newsgroups: comp.databases.postgresql.performance +Subject: Re: Recommended File System Configuration +Date: Mon, 03 May 2004 12:38:33 -0400 +Organization: cbbrowne Computing Inc +Lines: 43 +Message-ID: <60zn8pcvp2.fsf@dev6.int.libertyrms.info> +References: <4094AD20.6090707@jamesthornton.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Complaints-To: usenet@news.hub.org +User-Agent: Gnus/5.110002 (No Gnus v0.2) XEmacs/21.4 (Security Through + Obscurity, linux) +Cancel-Lock: sha1:3KfTEXaC2Mi1CC+e1U6GoFbsbJg= +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/13 +X-Sequence-Number: 6844 + +james@jamesthornton.com (James Thornton) writes: +> Back in 2001, there was a lengthy thread on the PG Hackers list about +> PG and journaling file systems +> (http://archives.postgresql.org/pgsql-hackers/2001-05/msg00017.php), +> but there was no decisive conclusion regarding what FS to use. At the +> time the fly in the XFS ointment was that deletes were slow, but this +> was improved with XFS 1.1. +> +> I think a journaling a FS is needed for PG data since large DBs could +> take hours to recover on a non-journaling FS, but what about WAL files? + +If the WAL files are on a small filesystem, it presumably won't take +hours for that filesystem to recover at fsck time. + +The results have not been totally conclusive... + + - Several have found JFS to be a bit faster than anything else on + Linux, but some data loss problems have been experienced; + + - ext2 has the significant demerit that with big filesystems, fsck + will "take forever" to run; + + - ext3 appears to be the slowest option out there, and there are some + stories of filesystem corruption; + + - ReiserFS was designed to be real fast with tiny files, which is not + the ideal "use case" for PostgreSQL; the designers there are + definitely the most aggressive at pushing out "bleeding edge" code, + which isn't likely the ideal; + + - XFS is neither fastest nor slowest, but there has been a lack of + reports of "spontaneous data loss" under heavy load, which is a + good thing. It's not part of "official 2.4" kernels, requiring + backports, but once 2.6 gets more widely deployed, this shouldn't + be a demerit anymore... + +I think that provides a reasonable overview of what has been seen... +-- +output = reverse("gro.gultn" "@" "enworbbc") +http://cbbrowne.com/info/oses.html +Donny: Are these the Nazis, Walter? +Walter: No, Donny, these men are nihilists. There's nothing to be +afraid of. -- The Big Lebowski + +From pgsql-performance-owner@postgresql.org Tue May 4 01:24:44 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 4C5EBD1EF86 + for ; + Mon, 3 May 2004 17:58:45 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 42915-06 + for ; + Mon, 3 May 2004 17:58:30 -0300 (ADT) +Received: from mwinf0303.wanadoo.fr (smtp3.wanadoo.fr [193.252.22.28]) + by svr1.postgresql.org (Postfix) with ESMTP id 5CCF5D1EFD9 + for ; + Mon, 3 May 2004 17:58:24 -0300 (ADT) +Received: from [192.168.0.2] (AMontsouris-108-1-16-56.w80-15.abo.wanadoo.fr + [80.15.145.56]) + by mwinf0303.wanadoo.fr (SMTP Server) with ESMTP id A92625000872 + for ; + Mon, 3 May 2004 22:58:31 +0200 (CEST) +Mime-Version: 1.0 (Apple Message framework v613) +Content-Transfer-Encoding: quoted-printable +Message-Id: +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +To: pgsql-performance@postgresql.org +From: =?ISO-8859-1?Q?Pailloncy_Jean-G=E9rard?= +Subject: INSERT RULE +Date: Mon, 3 May 2004 22:58:28 +0200 +X-Mailer: Apple Mail (2.613) +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.9 tagged_above=0.0 required=5.0 tests=RCVD_IN_SORBS, + SUBJ_ALL_CAPS, UPPERCASE_25_50 +X-Spam-Level: +X-Archive-Number: 200405/18 +X-Sequence-Number: 6849 + +Hi, + +I test a configuration where one table is divided in 256 sub-table. +And I use a RULE to offer a single view to the data. + +For INSERT I have create 256 rules like: +CREATE RULE ndicti_000 AS ON INSERT TO ndict + WHERE (NEW.word_id & 255) =3D 000 DO INSTEAD + INSERT INTO ndict_000 VALUES( NEW.url_id, 000, NEW.intag); +CREATE RULE ndicti_001 AS ON INSERT TO ndict + WHERE (NEW.word_id & 255) =3D 001 DO INSTEAD + INSERT INTO ndict_001 VALUES( NEW.url_id, 001, NEW.intag); +And that works, a bit slow. + +I try to do: +CREATE RULE ndicti AS ON INSERT TO ndict + DO INSTEAD INSERT INTO 'ndict_' || (NEW.word_id & 255) + VALUES( NEW.url_id, NEW.word_id, NEW.intag); +I got an error on 'ndict_' . +I did not found the right syntax. + +Any help is welcomed. + + +Cordialement, +Jean-G=E9rard Pailloncy + +From pgsql-performance-owner@postgresql.org Mon May 3 23:46:11 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 2B3F8D1E7B8 + for ; + Mon, 3 May 2004 23:46:10 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 42129-03 + for ; + Mon, 3 May 2004 23:45:57 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id CBB74D1E12E + for ; + Mon, 3 May 2004 23:45:49 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.12.9/8.12.9) with ESMTP id i442jnSx016972 + for ; Tue, 4 May 2004 02:45:49 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.12.9/8.12.9/Submit) id i442NqL8004948 + for pgsql-performance@postgresql.org; Tue, 4 May 2004 02:23:52 GMT +From: Joseph Shraibman +X-Newsgroups: comp.databases.postgresql.performance +Subject: cache table +Date: Mon, 03 May 2004 22:24:02 -0400 +Organization: Hub.Org Networking Services +Lines: 17 +Message-ID: +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7b) Gecko/20040421 +X-Accept-Language: en-us, en +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/14 +X-Sequence-Number: 6845 + +I have a big table with some int fields. I frequently need to do +queries like: + +SELECT if2, count(*) FROM table WHERE if1 = 20 GROUP BY if2; + +The problem is that this is slow and frequently requires a seqscan. I'd +like to cache the results in a second table and update the counts with +triggers, but this would a) require another UPDATE for each +INSERT/UPDATE which would slow down adding and updating of data and b) +produce a large amount of dead rows for vacuum to clear out. + +It would also be nice if this small table could be locked into the pg +cache somehow. It doesn't need to store the data on disk because the +counts can be generated from scratch? + +So what is the best solution to this problem? I'm sure it must come up +pretty often. + +From pgsql-performance-owner@postgresql.org Mon May 3 23:46:11 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 3A7D3D1E882 + for ; + Mon, 3 May 2004 23:46:10 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 39975-03 + for ; + Mon, 3 May 2004 23:45:58 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 44292D1E147 + for ; + Mon, 3 May 2004 23:45:50 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.12.9/8.12.9) with ESMTP id i442jnT1016972 + for ; Tue, 4 May 2004 02:45:49 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.12.9/8.12.9/Submit) id i442Ucxa008336 + for pgsql-performance@postgresql.org; Tue, 4 May 2004 02:30:38 GMT +From: Joseph Shraibman +X-Newsgroups: comp.databases.postgresql.performance +Subject: Re: linux distro for better pg performance +Date: Mon, 03 May 2004 22:30:48 -0400 +Organization: Hub.Org Networking Services +Lines: 10 +Message-ID: <40970058.3040608@selectacast.net> +References: <407E25A6.ADFE4815@t1.unisoftbg.com> <407E909F.9000101@ehpg.net> + <1082053706.10823.38.camel@localhost.localdomain> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: "J. Andrew Rogers" +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7b) Gecko/20040421 +X-Accept-Language: en-us, en +In-Reply-To: <1082053706.10823.38.camel@localhost.localdomain> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/15 +X-Sequence-Number: 6846 + +J. Andrew Rogers wrote: + +> Do these features make a difference? Far more than you would imagine. +> On one postgres server I just upgraded, we went from a 3Ware 8x7200-RPM +> RAID-10 configuration to an LSI 320-2 SCSI 3x10k RAID-5, with 256M + +Is raid 5 much faster than raid 10? On a 4 disk array with 3 data disks +and 1 parity disk, you have to write 4/3rds the original data, while on +raid 10 you have to write 2 times the original data, so logically raid 5 +should be faster. + +From pgsql-performance-owner@postgresql.org Tue May 4 00:47:18 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 8F794D1F01B + for ; + Tue, 4 May 2004 00:47:17 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 46378-09 + for ; + Tue, 4 May 2004 00:46:56 -0300 (ADT) +Received: from wren.rentec.com (unknown [65.213.84.9]) + by svr1.postgresql.org (Postfix) with ESMTP id B1771D1F003 + for ; + Tue, 4 May 2004 00:46:54 -0300 (ADT) +Received: from rentec.com (stangesun.rentec.com [172.16.160.106]) + by wren.rentec.com (8.12.1/8.12.1) with ESMTP id i443kieu004709; + Mon, 3 May 2004 23:46:44 -0400 (EDT) +Message-ID: <4097081B.7020006@rentec.com> +Date: Mon, 03 May 2004 23:03:55 -0400 +From: Alan Stange +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8a) Gecko/20040428 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Joseph Shraibman +Cc: "J. Andrew Rogers" , + pgsql-performance@postgresql.org +Subject: Re: linux distro for better pg performance +References: <407E25A6.ADFE4815@t1.unisoftbg.com> <407E909F.9000101@ehpg.net> + <1082053706.10823.38.camel@localhost.localdomain> + <40970058.3040608@selectacast.net> +In-Reply-To: <40970058.3040608@selectacast.net> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/17 +X-Sequence-Number: 6848 + +Joseph Shraibman wrote: + +> J. Andrew Rogers wrote: +> +>> Do these features make a difference? Far more than you would +>> imagine. On one postgres server I just upgraded, we went from a 3Ware +>> 8x7200-RPM +>> RAID-10 configuration to an LSI 320-2 SCSI 3x10k RAID-5, with 256M +> +> Is raid 5 much faster than raid 10? On a 4 disk array with 3 data +> disks and 1 parity disk, you have to write 4/3rds the original data, +> while on raid 10 you have to write 2 times the original data, so +> logically raid 5 should be faster. + +I think this comparison is a bit simplistic. For example, most raid5 +setups have full stripes that are more than 8K (the typical IO size in +postgresql), so one might have to read in portions of the stripe in +order to compute the parity. The needed bits might be in some disk or +controller cache; if it's not then you lose. If one is able to +perform full stripe writes then the raid5 config should be faster for +writes. + +Note also that the mirror has 2 copies of the data, so that the read IOs +would be divided across 2 (or more) spindles using round robin or a more +advanced algorithm to reduce seek times. + +Of course, I might be completely wrong... + +-- Alan + +From pgsql-performance-owner@postgresql.org Tue May 4 00:41:04 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 92BD9D1E40A + for ; + Tue, 4 May 2004 00:41:03 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 55330-03 + for ; + Tue, 4 May 2004 00:40:42 -0300 (ADT) +Received: from roam.unifiedmind.com (unifiedmind.com [209.164.72.58]) + by svr1.postgresql.org (Postfix) with SMTP id CF710D1DF6A + for ; + Tue, 4 May 2004 00:40:41 -0300 (ADT) +Received: (qmail 8693 invoked from network); 4 May 2004 04:02:09 -0000 +Received: from unknown (HELO jamesthornton.com) (james@69.150.60.163) + by 0 with SMTP; 4 May 2004 04:02:09 -0000 +Message-ID: <409710F8.10500@jamesthornton.com> +Date: Mon, 03 May 2004 22:41:44 -0500 +From: James Thornton +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.4) Gecko/20030624 Netscape/7.1 (ax) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Joseph Shraibman +Cc: "J. Andrew Rogers" , + pgsql-performance@postgresql.org +Subject: Re: linux distro for better pg performance +References: <407E25A6.ADFE4815@t1.unisoftbg.com> <407E909F.9000101@ehpg.net> + <1082053706.10823.38.camel@localhost.localdomain> + <40970058.3040608@selectacast.net> +In-Reply-To: <40970058.3040608@selectacast.net> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/16 +X-Sequence-Number: 6847 + +Joseph Shraibman wrote: + +> Is raid 5 much faster than raid 10? On a 4 disk array with 3 data disks +> and 1 parity disk, you have to write 4/3rds the original data, while on +> raid 10 you have to write 2 times the original data, so logically raid 5 +> should be faster. + +RAID 5 will give you more capacity, but is usually not recommended for +write intensive applications since RAID 5 writes require four I/O +operations: parity and data disks must be read, new data is compared to +data already on the drive and changes are noted, new parity is +calculated, both the parity and data disks are written to. Furthermore, +if a disk fails, performance is severely affected since all remaining +drives must be read for each I/O in order to recalculate the missing +disk drives data. + +RAID 0+1 has the same performance and capacity as RAID 1+0 (10), but +less reliability since "a single drive failure will cause the whole +array to become, in essence, a RAID Level 0 array" so I don't know why +anyone would choose it over RAID 10 where multiple disks can fail. + +RAID 1 has the same capacity as RAID 10 (n/2), but RAID 10 has better +performance so if you're going to have more than one drive pair, why not +go for RAID 10 and get the extra performance from striping? + +I have been researching how to configure Postgres for a RAID 10 SAME +configuration as described in the Oracle paper "Optimal Storage +Configuration Made Easy" +(http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has +anyone delved into this before? + +The filesystem choice is also a key element in database performance +tuning. In another Oracle paper entitled Tuning an "Oracle8i Database +Running Linux" +(http://otn.oracle.com/oramag/webcolumns/2002/techarticles/scalzo_linux02.html), +Dr. Bert Scalzo says, "The trouble with these tests-for example, Bonnie, +Bonnie++, Dbench, Iobench, Iozone, Mongo, and Postmark-is that they are +basic file system throughput tests, so their results generally do not +pertain in any meaningful fashion to the way relational database systems +access data files." Instead he suggests users benchmarking filesystems +for database applications should use these two well-known and widely +accepted database benchmarks: + +AS3AP (http://www.benchmarkresources.com/handbook/5.html): a scalable, +portable ANSI SQL relational database benchmark that provides a +comprehensive set of tests of database-processing power; has built-in +scalability and portability for testing a broad range of systems; +minimizes human effort in implementing and running benchmark tests; and +provides a uniform, metric, straightforward interpretation of the results. + +TPC-C (http://www.tpc.org/): an online transaction processing (OLTP) +benchmark that involves a mix of five concurrent transactions of various +types and either executes completely online or queries for deferred +execution. The database comprises nine types of tables, having a wide +range of record and population sizes. This benchmark measures the number +of transactions per second. + +I encourage you to read the paper -- Dr. Scalzo's results will surprise +you; however, while he benchmarked ext2, ext3, ReiserFS, JFS, and RAW, +he did not include XFS. + +SGI and IBM did a more detailed study on Linux filesystem performance, +which included XFS, ext2, ext3 (various modes), ReiserFS, and JRS, and +the results are presented in a paper entitled "Filesystem Performance +and Scalability in Linux 2.4.17" +(http://oss.sgi.com/projects/xfs/papers/filesystem-perf-tm.pdf). This +paper goes over the details on how to properly conduct a filesystem +benchmark and addresses scaling and load more so than Dr. Scalzo's tests. + +For further study, I have compiled a list of Linux filesystem resources +at: http://jamesthornton.com/hotlist/linux-filesystems/. +-- + + James Thornton +______________________________________________________ +Internet Business Consultant, http://jamesthornton.com + + +From pgsql-performance-owner@postgresql.org Tue May 4 03:03:41 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E573D1B837 + for ; + Tue, 4 May 2004 03:03:39 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 03097-01 + for ; + Tue, 4 May 2004 03:03:18 -0300 (ADT) +Received: from smtp.istop.com (dci.doncaster.on.ca [66.11.168.194]) + by svr1.postgresql.org (Postfix) with ESMTP id AE1C4D1DF6F + for ; + Tue, 4 May 2004 03:03:16 -0300 (ADT) +Received: from stark.xeocode.com (gsstark.mtl.istop.com [66.11.160.162]) + by smtp.istop.com (Postfix) with ESMTP + id 45FF917C436; Tue, 4 May 2004 02:03:17 -0400 (EDT) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1BKt1R-0004id-00; Tue, 04 May 2004 02:03:17 -0400 +To: Joseph Shraibman +Cc: "J. Andrew Rogers" , + pgsql-performance@postgresql.org +Subject: Re: linux distro for better pg performance +References: <407E25A6.ADFE4815@t1.unisoftbg.com> <407E909F.9000101@ehpg.net> + <1082053706.10823.38.camel@localhost.localdomain> + <40970058.3040608@selectacast.net> +In-Reply-To: <40970058.3040608@selectacast.net> +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 04 May 2004 02:03:16 -0400 +Message-ID: <87k6zszq3f.fsf@stark.xeocode.com> +Lines: 24 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/20 +X-Sequence-Number: 6851 + +Joseph Shraibman writes: + +> J. Andrew Rogers wrote: +> +> > Do these features make a difference? Far more than you would imagine. On one +> > postgres server I just upgraded, we went from a 3Ware 8x7200-RPM +> > RAID-10 configuration to an LSI 320-2 SCSI 3x10k RAID-5, with 256M +> +> Is raid 5 much faster than raid 10? On a 4 disk array with 3 data disks and 1 +> parity disk, you have to write 4/3rds the original data, while on raid 10 you +> have to write 2 times the original data, so logically raid 5 should be faster. + +In RAID5 every write needs to update the parity disk as well. In order to do +that for a small random access write you often need read in the rest of the +data block being modified to calculate the parity bits. This means writes +often have higher latency on RAID5 because they first have to do an extra +read. This is where RAID5 got its bad reputation. + +Good modern RAID5 controllers can minimize this problem but I think it's still +an issue for a lot of lower end hardware. I wonder if postgres's architecture +might minimize it already just because of the pattern of writes it generates. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Tue May 4 04:37:49 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id DECD8D1B97B + for ; + Tue, 4 May 2004 04:37:48 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 25372-10 + for ; + Tue, 4 May 2004 04:37:29 -0300 (ADT) +Received: from linda-2.paradise.net.nz (bm-2a.paradise.net.nz [202.0.58.21]) + by svr1.postgresql.org (Postfix) with ESMTP id 73FCDD1B8A2 + for ; + Tue, 4 May 2004 04:37:27 -0300 (ADT) +Received: from smtp-2.paradise.net.nz (smtp-2b.paradise.net.nz [202.0.32.211]) + by linda-2.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0HX600KMGIIF30@linda-2.paradise.net.nz> for + pgsql-performance@postgresql.org; Tue, 04 May 2004 19:37:27 +1200 (NZST) +Received: from paradise.net.nz + (218-101-12-151.paradise.net.nz [218.101.12.151]) by + smtp-2.paradise.net.nz (Postfix) with ESMTP id E3DE79E2AE; + Tue, 04 May 2004 19:37:26 +1200 (NZST) +Date: Tue, 04 May 2004 19:39:22 +1200 +From: Mark Kirkwood +Subject: Re: Fwd: FreeBSD, PostgreSQL, semwait and sbwait! +In-reply-to: <52623D23-9AA4-11D8-9268-000A95DE2550@gdr-isis.enst.fr> +To: =?ISO-8859-1?Q?Pailloncy_Jean-G=E9rard?= +Cc: pgsql-performance@postgresql.org +Message-id: <409748AA.2030801@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; charset=ISO-8859-1; format=flowed +Content-transfer-encoding: 8BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.6) Gecko/20040404 +References: <200403231248.34425.darcy@wavefire.com> + <40615443.4030003@paradise.net.nz> + <52623D23-9AA4-11D8-9268-000A95DE2550@gdr-isis.enst.fr> +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=2.2 tagged_above=0.0 required=5.0 + tests=RCVD_IN_BL_SPAMCOP_NET +X-Spam-Level: ** +X-Archive-Number: 200405/21 +X-Sequence-Number: 6852 + +I am wondering if your wait is caused by contention between +pg_autovacuum and the DELETE that is running. Your large Pg blocksize +(32K) *may* be contributing to any possible contention as well. Maybe +try disabling pg_autovacuum to see if there is any change in behaviour. + +Also going through my head is '32 Kb bock's size (to match ffs and raid +block's size)' - does that mean you have raid strip size = 32K? maybe +try 128K (I know it sounds like a bad thing, but generally raid stripes +of 128K->256K are better than 32K->64K) + +regards + +Mark + + +Pailloncy Jean-G�rard wrote: + +> Hello, +> +>> +> I found the same problem. +> +> I use OpenBSD 3.3, +> On Pentium 2,4 GHz with 1 Gb RAM, RAID 10. +> With PostgreSQL 7.4.1 with 32 Kb bock's size (to match ffs and raid +> block's size) +> With pg_autovacuum daemon from Pg 7.5. +> +> I run a web indexer. +> sd0 raid-1 with system pg-log and indexer-log +> sd1 raid-10 with pg-data and indexer-data +> The sd1 disk achives between 10 and 40 Mb/s on normal operation. +> +> When I get semwait in top, system waits ;-) +> Not much disk activity. +> Not much log in pg or indexer. +> Just wait.... +> + +From pgsql-performance-owner@postgresql.org Wed May 5 13:57:31 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id CC107D1B4A3 + for ; + Tue, 4 May 2004 07:13:49 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 81955-05 + for ; + Tue, 4 May 2004 07:13:31 -0300 (ADT) +Received: from mwinf0602.wanadoo.fr (smtp6.wanadoo.fr [193.252.22.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 60A10D1B4E7 + for ; + Tue, 4 May 2004 07:13:26 -0300 (ADT) +Received: from [192.168.0.2] (AMontsouris-108-1-16-56.w80-15.abo.wanadoo.fr + [80.15.145.56]) + by mwinf0602.wanadoo.fr (SMTP Server) with ESMTP id B8E4F5400717 + for ; + Tue, 4 May 2004 12:13:28 +0200 (CEST) +Mime-Version: 1.0 (Apple Message framework v613) +In-Reply-To: +References: +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Message-Id: +Content-Transfer-Encoding: quoted-printable +From: =?ISO-8859-1?Q?Pailloncy_Jean-G=E9rard?= +Subject: Re: INSERT RULE +Date: Tue, 4 May 2004 12:13:26 +0200 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.613) +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.4 tagged_above=0.0 required=5.0 tests=RCVD_IN_SORBS, + UPPERCASE_25_50 +X-Spam-Level: +X-Archive-Number: 200405/36 +X-Sequence-Number: 6867 + +> I try to do: +> CREATE RULE ndicti AS ON INSERT TO ndict +> DO INSTEAD INSERT INTO 'ndict_' || (NEW.word_id & 255) +> VALUES( NEW.url_id, NEW.word_id, NEW.intag); +> I got an error on 'ndict_' . +> I did not found the right syntax. +In fact I discover that +SELECT * FROM / INSERT INTO table +doesn't accept function that returns the name of the table as table,=20 +but only function that returns rows.... + +I'm dead. + +Does this feature, is possible or plan ? +Is there a trick to do it ? + +Cordialement, +Jean-G=E9rard Pailloncy + + +From pgsql-performance-owner@postgresql.org Tue May 4 09:06:27 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 0C903D1E5C4 + for ; + Tue, 4 May 2004 09:06:25 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 17535-07 + for ; + Tue, 4 May 2004 09:06:07 -0300 (ADT) +Received: from hotmail.com (bay18-dav5.bay18.hotmail.com [65.54.187.185]) + by svr1.postgresql.org (Postfix) with ESMTP id C226ED1B4A3 + for ; + Tue, 4 May 2004 09:06:03 -0300 (ADT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Tue, 4 May 2004 05:06:07 -0700 +Received: from 67.81.102.201 by bay18-dav5.bay18.hotmail.com with DAV; + Tue, 04 May 2004 12:06:06 +0000 +X-Originating-IP: [67.81.102.201] +X-Originating-Email: [awerman2@hotmail.com] +X-Sender: awerman2@hotmail.com +From: "Aaron Werman" +To: "Alan Stange" +Cc: +References: <407E25A6.ADFE4815@t1.unisoftbg.com> <407E909F.9000101@ehpg.net> + <1082053706.10823.38.camel@localhost.localdomain> + <40970058.3040608@selectacast.net> <4097081B.7020006@rentec.com> +Subject: Re: linux distro for better pg performance +Date: Tue, 4 May 2004 08:06:22 -0400 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1409 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 +Message-ID: +X-OriginalArrivalTime: 04 May 2004 12:06:07.0134 (UTC) + FILETIME=[2E3413E0:01C431D0] +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.2 tagged_above=0.0 required=5.0 tests=RCVD_IN_NJABL, + RCVD_IN_SORBS +X-Spam-Level: +X-Archive-Number: 200405/22 +X-Sequence-Number: 6853 + +The comparison is actually dead on. If you have lots of write through / read +behind cache, RAID 5 can run very quickly, until the write rate overwhelms +the cache - at which point the 4 I/O per write / 2 per read stops it. This +means that RAID 5 works, except when stressed, which is a bad paradigm. + +If you do streaming sequential writes on RAID5 on a 4 drive RAID5, 4 writes +become: + +- read drive 1 for data +- read drive 3 for parity +- write changes to drive 1 +- write changes to drive 3 + +- read drive 2 for data +- read drive 4 for parity +- write changes to drive 2 +- write changes to drive 4 + +- read drive 3 for data +- read drive 1 for parity +- write changes to drive 3 +- write changes to drive 1 + +- read drive 4 for data +- read drive 2 for parity +- write changes to drive 4 +- write changes to drive 2 + +or + +drive 1: 2 reads, 2 writes +drive 2: 2 reads, 2 writes +drive 3: 2 reads, 2 writes +drive 4: 2 reads, 2 writes + +in other words, evenly distributed 16 I/Os. These have to be ordered to be +recoverable (otherwise the parity scheme is broken and you can't recover), +and thus are quasi synchronous. + +The same on RAID 10 is + +- write changes to drive 1 +- write copy of changes to drive 2 +- write changes to drive 1 +- write copy of changes to drive 2 +- write changes to drive 1 +- write copy of changes to drive 2 +- write changes to drive 1 +- write copy of changes to drive 2 + +or + +drive 1: 4 I/Os +drive 2: 4 I/Os + +in other words 4 I/Os in parallel. There is no wait on streaming I/O on RAID +10, and this fact is the other main reason RAID 10 gives an order of +magnitude better performance. + +If you are writing full blocks in a streaming mode, RAID 3 will be the +fastest - it is RAID 0 with a parity drive. In every situation I've seen it, +RAID 5 was either generally slow or got applications into trouble during +stress: bulk loads, etc. Most DBAs end up on RAID 10 for it's predictability +and performance. + +/Aaron + +----- Original Message ----- +From: "Alan Stange" +To: "Joseph Shraibman" +Cc: "J. Andrew Rogers" ; + +Sent: Monday, May 03, 2004 11:03 PM +Subject: Re: [PERFORM] linux distro for better pg performance + + +> Joseph Shraibman wrote: +> +> > J. Andrew Rogers wrote: +> > +> >> Do these features make a difference? Far more than you would +> >> imagine. On one postgres server I just upgraded, we went from a 3Ware +> >> 8x7200-RPM +> >> RAID-10 configuration to an LSI 320-2 SCSI 3x10k RAID-5, with 256M +> > +> > Is raid 5 much faster than raid 10? On a 4 disk array with 3 data +> > disks and 1 parity disk, you have to write 4/3rds the original data, +> > while on raid 10 you have to write 2 times the original data, so +> > logically raid 5 should be faster. +> +> I think this comparison is a bit simplistic. For example, most raid5 +> setups have full stripes that are more than 8K (the typical IO size in +> postgresql), so one might have to read in portions of the stripe in +> order to compute the parity. The needed bits might be in some disk or +> controller cache; if it's not then you lose. If one is able to +> perform full stripe writes then the raid5 config should be faster for +> writes. +> +> Note also that the mirror has 2 copies of the data, so that the read IOs +> would be divided across 2 (or more) spindles using round robin or a more +> advanced algorithm to reduce seek times. +> +> Of course, I might be completely wrong... +> +> -- Alan +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster +> + +From pgsql-performance-owner@postgresql.org Tue May 4 10:55:50 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 20A4DD1F0A7 + for ; + Tue, 4 May 2004 10:55:49 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 70950-02 + for ; + Tue, 4 May 2004 10:55:32 -0300 (ADT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by svr1.postgresql.org (Postfix) with ESMTP id 60CABD1E131 + for ; + Tue, 4 May 2004 10:55:28 -0300 (ADT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.10/8.12.10) with ESMTP id i44DtJBO010303; + Tue, 4 May 2004 07:55:19 -0600 (MDT) +Date: Tue, 4 May 2004 07:52:12 -0600 (MDT) +From: "scott.marlowe" +To: Joseph Shraibman +Cc: +Subject: Re: cache table +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-IHS-MailScanner: Found to be clean +X-IHS-MailScanner-SpamCheck: +X-IHS-MailScanner-Envelope-Sender: scott.marlowe@ihs.com +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/23 +X-Sequence-Number: 6854 + +On Mon, 3 May 2004, Joseph Shraibman wrote: + +> I have a big table with some int fields. I frequently need to do +> queries like: +> +> SELECT if2, count(*) FROM table WHERE if1 = 20 GROUP BY if2; +> +> The problem is that this is slow and frequently requires a seqscan. I'd +> like to cache the results in a second table and update the counts with +> triggers, but this would a) require another UPDATE for each +> INSERT/UPDATE which would slow down adding and updating of data and b) +> produce a large amount of dead rows for vacuum to clear out. +> +> It would also be nice if this small table could be locked into the pg +> cache somehow. It doesn't need to store the data on disk because the +> counts can be generated from scratch? + +I think you might be interested in materialized views. You could create +this as a materialized view which should be very fast to just select * +from. + +While materialized views aren't a standard part of PostgreSQL just yet, +there is a working implementation available from Jonathan Gardner at: + +http://jonathangardner.net/PostgreSQL/materialized_views/matviews.html + +It's all implemented with plpgsql and is quite interesting to read +through. IT has a nice tutorial methodology to it. + + +From pgsql-performance-owner@postgresql.org Tue May 4 12:46:42 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 1B239D1DF29 + for ; + Tue, 4 May 2004 12:46:41 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 14839-10 + for ; + Tue, 4 May 2004 12:46:07 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 206D1D1B520 + for ; + Tue, 4 May 2004 12:46:07 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.12.9/8.12.9) with ESMTP id i44Fk6Sx050540 + for ; Tue, 4 May 2004 15:46:06 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.12.9/8.12.9/Submit) id i44FRsdR042648 + for pgsql-performance@postgresql.org; Tue, 4 May 2004 15:27:54 GMT +From: Joseph Shraibman +X-Newsgroups: comp.databases.postgresql.performance +Subject: Re: cache table +Date: Tue, 04 May 2004 11:27:53 -0400 +Organization: Hub.Org Networking Services +Lines: 9 +Message-ID: <4097B679.60301@selectacast.net> +References: + +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: "scott.marlowe" +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7b) Gecko/20040421 +X-Accept-Language: en-us, en +In-Reply-To: +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/24 +X-Sequence-Number: 6855 + +scott.marlowe wrote: + +> I think you might be interested in materialized views. You could create +> this as a materialized view which should be very fast to just select * +> from. + +That seems to be the count table I envisioned. It just hides the +details for me. It still has the problems of an extra UPDATE every time +the data table is updated and generating a lot of dead tuples. + +From pgsql-performance-owner@postgresql.org Tue May 4 13:32:13 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 7AA5DD1E0DE + for ; + Tue, 4 May 2004 13:32:11 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 36914-10 + for ; + Tue, 4 May 2004 13:31:51 -0300 (ADT) +Received: from wolff.to (wolff.to [66.93.249.74]) + by svr1.postgresql.org (Postfix) with SMTP id 327CAD1F07D + for ; + Tue, 4 May 2004 13:31:50 -0300 (ADT) +Received: (qmail 10987 invoked by uid 500); 4 May 2004 16:36:19 -0000 +Date: Tue, 4 May 2004 11:36:19 -0500 +From: Bruno Wolff III +To: Timo Nentwig +Cc: pgsql-performance@postgresql.org, support@postgresql.org +Subject: Re: Bug in optimizer +Message-ID: <20040504163619.GB10698@wolff.to> +Mail-Followup-To: pgsql-performance@postgresql.org, bruno@wolff.to +References: <40966E77.4020004@nitwit.de> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <40966E77.4020004@nitwit.de> +User-Agent: Mutt/1.5.6i +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/25 +X-Sequence-Number: 6856 + +On Mon, May 03, 2004 at 18:08:23 +0200, + Timo Nentwig wrote: +> +> This is very slow: + +This kind of question should be asked on the performance list. + +> +> SELECT urls.id FROM urls WHERE +> ( +> urls.id <> ALL (SELECT html.urlid FROM html) +> ); +> +> ...while this is quite fast: + +You didn't provide your postgres version or an explain analyze so it is hard +to answer your question definitivly. Most likely you are using a pre 7.4 +version which is know to be slow for IN (which is what the above probably +gets translated to). + +> +> SELECT urls.id FROM urls WHERE +> ( +> NOT (EXISTS (SELECT html.urlid FROM tml WHERE +> ( +> html.urlid = urls.id +> ))) +> ); + +From pgsql-performance-owner@postgresql.org Tue May 4 15:15:03 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 68FD5D1F057 + for ; + Tue, 4 May 2004 15:15:00 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 90497-02 + for ; + Tue, 4 May 2004 15:14:39 -0300 (ADT) +Received: from smtp.istop.com (dci.doncaster.on.ca [66.11.168.194]) + by svr1.postgresql.org (Postfix) with ESMTP id 693A5D1F0E2 + for ; + Tue, 4 May 2004 15:14:36 -0300 (ADT) +Received: from stark.xeocode.com (gsstark.mtl.istop.com [66.11.160.162]) + by smtp.istop.com (Postfix) with ESMTP + id D0E5917C028; Tue, 4 May 2004 14:14:15 -0400 (EDT) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1BL4Qp-0007AT-00; Tue, 04 May 2004 14:14:15 -0400 +To: Joseph Shraibman +Cc: "scott.marlowe" , pgsql-performance@postgresql.org +Subject: Re: cache table +References: + + <4097B679.60301@selectacast.net> +In-Reply-To: <4097B679.60301@selectacast.net> +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 04 May 2004 14:14:15 -0400 +Message-ID: <87wu3sxdoo.fsf@stark.xeocode.com> +Lines: 39 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/26 +X-Sequence-Number: 6857 + +Joseph Shraibman writes: + +> scott.marlowe wrote: +> +> > I think you might be interested in materialized views. You could create this +> > as a materialized view which should be very fast to just select * from. +> +> That seems to be the count table I envisioned. It just hides the details for +> me. It still has the problems of an extra UPDATE every time the data table is +> updated and generating a lot of dead tuples. + +The dead tuples is only going to be a problem if you have lots of updates. If +that's the case then you're also going to have problems with contention. This +trigger will essentially serialize all inserts, deletes, updates at least +within a group. If you use transactions with multiple such updates then you +will also risk creating deadlocks. + +But I think these problems are fundamental to the problem you've described. +Keeping denormalized aggregate data like this inherently creates contention on +the data and generates lots of old data. It's only really useful when you have +few updates and many many reads. + +If you know more about the behaviour of the updates then there might be other +options. Like, do you need precise data or only approximate data? If +approximate perhaps you could just do a periodic refresh of the denormalized +view and use that. + +Are all the updates to the data you'll be querying coming from within the same +application context? In which case you can keep a cache locally in the +application and update it locally. I often do this when I have rarely updated +or insert-only data, I just do a lazy cache using a perl hash or equivalent. + +If you're really happy with losing the cache, and you don't need complex +transactions or care about serializing updates then you could use something +like memcached (http://www.danga.com/memcached/). That might be your best fit +for how you describe your requirements. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Tue May 4 15:44:42 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id C4C21D1E5C9 + for ; + Tue, 4 May 2004 15:44:41 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 96075-06 + for ; + Tue, 4 May 2004 15:44:18 -0300 (ADT) +Received: from web13121.mail.yahoo.com (web13121.mail.yahoo.com + [216.136.174.83]) + by svr1.postgresql.org (Postfix) with SMTP id 7EEC3D1E5C1 + for ; + Tue, 4 May 2004 15:44:16 -0300 (ADT) +Message-ID: <20040504184416.11114.qmail@web13121.mail.yahoo.com> +Received: from [63.78.248.48] by web13121.mail.yahoo.com via HTTP; + Tue, 04 May 2004 11:44:16 PDT +Date: Tue, 4 May 2004 11:44:16 -0700 (PDT) +From: Litao Wu +Subject: pg_stat +To: pgsql-performance@postgresql.org +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/27 +X-Sequence-Number: 6858 + +Hi, + +I have query: +select pg_stat_get_numscans(76529669), +pg_stat_get_blocks_fetched(76529669), +pg_stat_get_blocks_hit(76529669); + +The result is: + pg_stat_get_numscans | pg_stat_get_blocks_fetched | +pg_stat_get_blocks_hit +----------------------+----------------------------+------------------------ + 0 | 23617 | + 23595 +(1 row) + +My questions are: +1. How can index disk blocks be requested (either +from disk or cache) without index scan? +2. If I want to check if an index is used after +pg_stat_reset(), how can I get it? By number of scans +or block requests, or some other ways? + +Thanks, + + + + +__________________________________ +Do you Yahoo!? +Win a $20,000 Career Makeover at Yahoo! HotJobs +http://hotjobs.sweepstakes.yahoo.com/careermakeover + +From pgsql-performance-owner@postgresql.org Tue May 4 16:33:25 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id EEF85D1E5E8 + for ; + Tue, 4 May 2004 16:33:23 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 17492-03 + for ; + Tue, 4 May 2004 16:33:04 -0300 (ADT) +Received: from roam.unifiedmind.com (unifiedmind.com [209.164.72.58]) + by svr1.postgresql.org (Postfix) with SMTP id 3A4AFD1E5F3 + for ; + Tue, 4 May 2004 16:33:01 -0300 (ADT) +Received: (qmail 17963 invoked from network); 4 May 2004 19:54:33 -0000 +Received: from unknown (HELO jamesthornton.com) (james@69.150.60.163) + by 0 with SMTP; 4 May 2004 19:54:33 -0000 +Message-ID: <4097F02A.9010301@jamesthornton.com> +Date: Tue, 04 May 2004 14:34:02 -0500 +From: James Thornton +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.4) Gecko/20030624 Netscape/7.1 (ax) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Adapting Oracle S.A.M.E. Methodology for Postgres +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=1.3 tagged_above=0.0 required=5.0 tests=GAPPY_SUBJECT +X-Spam-Level: * +X-Archive-Number: 200405/28 +X-Sequence-Number: 6859 + +I mentioned this at the tail end of a long post in another thread, but +I have been researching how to configure Postgres for a RAID 10 SAME +configuration as described in the Oracle paper "Optimal Storage +Configuration Made Easy" +(http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has +anyone delved into this before? + +-- + + James Thornton +______________________________________________________ +Internet Business Consultant, http://jamesthornton.com + + + +From pgsql-performance-owner@postgresql.org Tue May 4 16:38:35 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 91C5AD1F0EB + for ; + Tue, 4 May 2004 16:38:33 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 18611-04 + for ; + Tue, 4 May 2004 16:38:12 -0300 (ADT) +Received: from roam.unifiedmind.com (unifiedmind.com [209.164.72.58]) + by svr1.postgresql.org (Postfix) with SMTP id 783B2D1F0C4 + for ; + Tue, 4 May 2004 16:37:55 -0300 (ADT) +Received: (qmail 18084 invoked from network); 4 May 2004 19:59:18 -0000 +Received: from unknown (HELO jamesthornton.com) (james@69.150.60.163) + by 0 with SMTP; 4 May 2004 19:59:18 -0000 +Message-ID: <4097F147.6050000@jamesthornton.com> +Date: Tue, 04 May 2004 14:38:47 -0500 +From: James Thornton +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.4) Gecko/20030624 Netscape/7.1 (ax) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Chris Browne +Cc: pgsql-performance@postgresql.org +Subject: Re: Recommended File System Configuration +References: <4094AD20.6090707@jamesthornton.com> + <60zn8pcvp2.fsf@dev6.int.libertyrms.info> +In-Reply-To: <60zn8pcvp2.fsf@dev6.int.libertyrms.info> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/29 +X-Sequence-Number: 6860 + +Chris Browne wrote: + +> The results have not been totally conclusive... +> +> - Several have found JFS to be a bit faster than anything else on +> Linux, but some data loss problems have been experienced; +> +> - ext2 has the significant demerit that with big filesystems, fsck +> will "take forever" to run; +> +> - ext3 appears to be the slowest option out there, and there are some +> stories of filesystem corruption; + + +In an Oracle paper entitled Tuning an "Oracle8i Database Running Linux" +(http://otn.oracle.com/oramag/webcolumns/2002/techarticles/scalzo_linux02.html), +Dr. Bert Scalzo says, "The trouble with these tests-for example, Bonnie, +Bonnie++, Dbench, Iobench, Iozone, Mongo, and Postmark-is that they are +basic file system throughput tests, so their results generally do not +pertain in any meaningful fashion to the way relational database systems +access data files." Instead he suggests users benchmarking filesystems +for database applications should use these two well-known and widely +accepted database benchmarks: + +AS3AP (http://www.benchmarkresources.com/handbook/5.html): a scalable, +portable ANSI SQL relational database benchmark that provides a +comprehensive set of tests of database-processing power; has built-in +scalability and portability for testing a broad range of systems; +minimizes human effort in implementing and running benchmark tests; and +provides a uniform, metric, straightforward interpretation of the results. + +TPC-C (http://www.tpc.org/): an online transaction processing (OLTP) +benchmark that involves a mix of five concurrent transactions of various +types and either executes completely online or queries for deferred +execution. The database comprises nine types of tables, having a wide +range of record and population sizes. This benchmark measures the number +of transactions per second. + +I encourage you to read the paper -- Dr. Scalzo's results will surprise +you; however, while he benchmarked ext2, ext3, ReiserFS, JFS, and RAW, +he did not include XFS. + +SGI and IBM did a more detailed study on Linux filesystem performance, +which included XFS, ext2, ext3 (various modes), ReiserFS, and JRS, and +the results are presented in a paper entitled "Filesystem Performance +and Scalability in Linux 2.4.17" +(http://oss.sgi.com/projects/xfs/papers/filesystem-perf-tm.pdf). This +paper goes over the details on how to properly conduct a filesystem +benchmark and addresses scaling and load more so than Dr. Scalzo's tests. + +For further study, I have compiled a list of Linux filesystem resources +at: http://jamesthornton.com/hotlist/linux-filesystems/. + +-- + + James Thornton +______________________________________________________ +Internet Business Consultant, http://jamesthornton.com + + +From pgsql-performance-owner@postgresql.org Tue May 4 19:15:45 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 8A83FD1F0F6 + for ; + Tue, 4 May 2004 19:15:44 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 74214-03 + for ; + Tue, 4 May 2004 19:15:26 -0300 (ADT) +Received: from smtp.istop.com (dci.doncaster.on.ca [66.11.168.194]) + by svr1.postgresql.org (Postfix) with ESMTP id 84A09D1F116 + for ; + Tue, 4 May 2004 19:15:23 -0300 (ADT) +Received: from stark.xeocode.com (gsstark.mtl.istop.com [66.11.160.162]) + by smtp.istop.com (Postfix) with ESMTP + id DBCB117C10E; Tue, 4 May 2004 18:15:25 -0400 (EDT) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1BL8CD-0008Nl-00; Tue, 04 May 2004 18:15:25 -0400 +To: Tom Lane +Cc: Greg Stark , Dennis Bjorklund , + Bruno Wolff III , "Jim C. Nasby" , + pgsql-performance@postgresql.org +Subject: Re: Horribly slow hash join +References: + <874qrg7cy8.fsf@stark.xeocode.com> <16041.1082354970@sss.pgh.pa.us> +In-Reply-To: <16041.1082354970@sss.pgh.pa.us> +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 04 May 2004 18:15:25 -0400 +Message-ID: <87llk7yh36.fsf@stark.xeocode.com> +Lines: 64 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/30 +X-Sequence-Number: 6861 + + +Tom Lane writes: + +> Modding by a *non* power of 2 (esp. a prime) mixes the bits quite well, +> and is likely faster than any multiple-instruction way to do the same. +> +> The quoted article seems to be by someone who has spent a lot of time +> counting assembly cycles and none at all reading the last thirty years +> worth of CS literature. Knuth's treatment of hashing has some actual +> math to it... + +[incidentally, I just found that the quoted article was independently found by +Bruce Momjian who found it convincing enough to convert the hash_any table +over to it two years ago] + +I just reviewed Knuth as well as C.L.R. and several papers from CACM and +SIGMOD. + +It seems we have three options: + +mod(): + + Pro: empirical research shows it the best algorithm for avoiding collisions + + Con: requires the hash table be a prime size and far from a power of two. + This is inconvenient to arrange for dynamic tables as used in postgres. + +multiplication method (floor(tablesize * remainder(x * golden ratio))) + + Pro: works with any table size + + Con: I'm not clear if it can be done without floating point arithmetic. + It seems like it ought to be possible though. + +Universal hashing: + + Pro: won't create gotcha situations where the distribution of data suddenly + and unexpectedly creates unexpected performance problems. + + Con: more complex. + +It would be trivial to switch the implementation from mod() to the +multiplicative method which is more suited to postgres's needs. However +universal hashing has some appeal. I hate the idea that a hash join could +perform perfectly well one day and suddenly become pessimal when new data is +loaded. + +In a sense universal hashing is less predictable. For a DSS system that could +be bad. A query that runs fine every day might fail one day in an +unpredictable way even though the data is unchanged. + +But in another sense it would be more predictable in that if you run the query +a thousand times the average performance would be very close to the expected +regardless of what the data is. Whereas more traditional algorithms have some +patterns of data that will consistently perform badly. + +It's probably not worth it but postgres could maybe even be tricky and pretest +the parameters against the common values in the statistics table, generating +new ones if they fail to generate a nice distribution. That doesn't really +guarantee anything though, except that those common values would at least be +well distributed to start with. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Tue May 4 20:35:11 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 66FB3D1CA43 + for ; + Tue, 4 May 2004 20:35:10 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 98685-01 + for ; + Tue, 4 May 2004 20:34:51 -0300 (ADT) +Received: from 3months.com (unknown [203.96.25.18]) + by svr1.postgresql.org (Postfix) with ESMTP id BF0C9D1EB44 + for ; + Tue, 4 May 2004 20:34:47 -0300 (ADT) +Received: from Spooler by 3months.com (Mercury/32 v4.01a) ID MO00020B; + 5 May 2004 11:31:29 +1200 +Received: from spooler by 3months.com (Mercury/32 v4.01a); + 5 May 2004 11:31:24 +1200 +Received: from Cyrillelaptop (203.96.25.15) by 3months.com (Mercury/32 v4.01a) + with ESMTP ID MG00004F; 5 May 2004 11:31:21 +1200 +From: "Cyrille Bonnet" +To: +Subject: very high CPU usage in "top", but not in "mpstat" +Date: Wed, 5 May 2004 11:34:41 +1200 +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_NextPart_000_0018_01C43294.F4B6B620" +X-Mailer: Microsoft Office Outlook, Build 11.0.5510 +Thread-Index: AcQyMF9N3R0vP6P2T4aKHdZRNbaNdg== +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 +Message-ID: <47E18B2A3472@3months.com> +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.1 tagged_above=0.0 required=5.0 tests=HTML_60_70, + HTML_MESSAGE +X-Spam-Level: +X-Archive-Number: 200405/31 +X-Sequence-Number: 6862 + +This is a multi-part message in MIME format. + +------=_NextPart_000_0018_01C43294.F4B6B620 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: 7bit + +Hello all, + + + +We are using Postgres 7.3 with JBoss 3.2.3 on a Linux Fedora 1.0 box. + + + +When I am looking at CPU activity with "top", I often see something like: + + + + PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND + +14154 postgres 25 0 3592 3592 2924 R 99.1 0.3 +93:53 0 postmaster + + + +At the same time, "mpstat" gives me something like: + + + +11:27:21 AM CPU %user %nice %system %idle intr/s + +11:27:21 AM all 2.99 0.00 18.94 78.08 105.94 + + + +The system is not visibly slow and response time is satisfactory. Sometimes, +the CPU usage drops to 1 or 2%, but not for long usually. Also I have +checked the number of open connections to Postgres and there are only 5 +(maximum is set to the default: 32). + + + +Should I be worried that Postgres is eating up 99% of my CPU??? Or is this +*expected* behaviour? + + + +Please note that I am a developer, not a system administrator, so maybe I +misunderstand the usage of "top" here. + + + +Any help will be appreciated. + + + +Cyrille. + + +------=_NextPart_000_0018_01C43294.F4B6B620 +Content-Type: text/html; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable + + + + + + + + + + + + +
+ +

Hello all,

+ +

 

+ +

We are using Postgres 7.3 with JBoss 3.2.3 on a Linux Fe= +dora +1.0 box.

+ +

 

+ +

When I am looking at CPU activity with “top”= +, I +often see something like:

+ +

 

+ +

  PID USER     PRI  NI&nbs= +p; +SIZE  RSS SHARE STAT %CPU %MEM   TIME CPU COMMAND= +

+ +

14154 postgres  25   0  3592 3592&nb= +sp; +2924        R    99.1&nbs= +p;     0.3 +       93:53   0 postmaster

+ +

 

+ +

At the same time, “mpstat” gives me something +like:

+ +

 

+ +

11:27:21 AM  CPU   %user   %nice +%system   %idle    intr/s= +

+ +

11:27:21 AM  all      &nbs= +p;2.99    +  0.00   18.94       &nbs= +p; 78.08    +105.94

+ +

 

+ +

The system is not visibly slow and response time is +satisfactory. Sometimes, the CPU usage drops to 1 or 2%, but not for long +usually. Also I have checked the number of open connections to Postgres and +there are only 5 (maximum is set to the default: 32).

+ +

 

+ +

Should I be worried that Postgres is eating up 99% of my +CPU??? Or is this *expected* +behaviour?

+ +

 

+ +

Please note that I am a developer, not a system +administrator, so maybe I misunderstand the usage of “top” here= +.

+ +

 

+ +

Any help will be appreciated. + +

 

+ +

Cyrille.

+ +
+ + + + + +------=_NextPart_000_0018_01C43294.F4B6B620-- + + + +From pgsql-performance-owner@postgresql.org Wed May 5 10:03:43 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id C05E2D1E7C7 + for ; + Wed, 5 May 2004 10:03:40 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 26637-01 + for ; + Wed, 5 May 2004 10:03:18 -0300 (ADT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id CC142D1E7C4 + for ; + Wed, 5 May 2004 10:03:14 -0300 (ADT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i45D3Ftm024917; + Wed, 5 May 2004 09:03:16 -0400 (EDT) +To: "Cyrille Bonnet" +Cc: pgsql-performance@postgresql.org +Subject: Re: very high CPU usage in "top", but not in "mpstat" +In-reply-to: <47E18B2A3472@3months.com> +References: <47E18B2A3472@3months.com> +Comments: In-reply-to "Cyrille Bonnet" + message dated "Wed, 05 May 2004 11:34:41 +1200" +Date: Wed, 05 May 2004 09:03:15 -0400 +Message-ID: <24916.1083762195@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/32 +X-Sequence-Number: 6863 + +"Cyrille Bonnet" writes: +> Should I be worried that Postgres is eating up 99% of my CPU??? Or is this +> *expected* behaviour? + +It's not expected, unless you are running some very long-running query. + +The conflict between what top says and what mpstat says is strange; I +wonder if you might have a buggy version of one of them? You should +probably check some other tools (try "vmstat 1" for instance) to see if +you can get a consensus on whether the CPU is maxed out or not ... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed May 5 14:18:19 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id AFECBD1F3CF + for ; + Wed, 5 May 2004 14:16:58 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 46786-08 + for ; + Wed, 5 May 2004 14:16:32 -0300 (ADT) +Received: from candle.pha.pa.us (candle.pha.pa.us [207.106.42.251]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E250D1F1DD + for ; + Wed, 5 May 2004 14:03:39 -0300 (ADT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.11.6) id i45H3Uc22406; + Wed, 5 May 2004 13:03:30 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200405051703.i45H3Uc22406@candle.pha.pa.us> +Subject: Re: History of oids in postgres? +In-Reply-To: <0B7369F9-9918-11D8-A107-000A9566A412@socialserve.com> +To: James Robinson +Date: Wed, 5 May 2004 13:03:30 -0400 (EDT) +Cc: bruno@wolff.to, pgsql-performance@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL108 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/38 +X-Sequence-Number: 6869 + +James Robinson wrote: +> Bruno et al, +> +> Any self-repsecting lurker would know that oids as row identifiers are +> depreciated in postgres. Can anyone provide a brief history regarding +> the reasoning behind using them as row identifiers in the first place? +> I see a discussion of their use as various primary keys in he system +> catalog in the oid-datatype doc page, but not regarding their history +> as 'user-space' row ids. + +They were added at Berkeley and I think are related to the +Object-relational ability of PostgreSQL. I think the newer SQL +standards have a similar capability specified. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + +From pgsql-bugs-owner@postgresql.org Wed May 5 16:16:47 2004 +X-Original-To: pgsql-bugs-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 73E79D1CA39 + for ; + Wed, 5 May 2004 14:46:42 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 64226-03 + for ; + Wed, 5 May 2004 14:46:22 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id DC474D1D06C + for ; Wed, 5 May 2004 14:46:21 -0300 (ADT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.12.9/8.12.9) with ESMTP id i45HkKSx028561 + for ; Wed, 5 May 2004 17:46:20 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.12.9/8.12.9/Submit) id i45HVDiN000543 + for pgsql-bugs@postgresql.org; Wed, 5 May 2004 17:31:13 GMT +From: Gaetano Mendola +X-Newsgroups: comp.databases.postgresql.bugs +Subject: Re: Bug in optimizer +Date: Wed, 05 May 2004 19:31:01 +0200 +Organization: PYRENET Midi-pyrenees Provider +Lines: 28 +Message-ID: <409924D5.1090001@bigfoot.com> +References: <40966E77.4020004@nitwit.de> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: abuse@pyrenet.fr +To: Timo Nentwig +User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502) +X-Accept-Language: en-us, en +In-Reply-To: <40966E77.4020004@nitwit.de> +To: pgsql-bugs@postgresql.org +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, + hits=0.3 tagged_above=0.0 required=5.0 tests=UPPERCASE_25_50 +X-Spam-Level: +X-Archive-Number: 200405/32 +X-Sequence-Number: 8304 + +Timo Nentwig wrote: + +> This is very slow: +> +> SELECT urls.id FROM urls WHERE +> ( +> urls.id <> ALL (SELECT html.urlid FROM html) +> ); +> +> ...while this is quite fast: +> +> SELECT urls.id FROM urls WHERE +> ( +> NOT (EXISTS (SELECT html.urlid FROM tml WHERE +> ( +> html.urlid = urls.id +> ))) +> ); + +Are you using the version 7.4.x ? + + + +Regards +Gaetano Mendola + + + + +From pgsql-performance-owner@postgresql.org Wed May 5 16:30:31 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id E7760D1F212 + for ; + Wed, 5 May 2004 14:37:09 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 57624-09 + for ; + Wed, 5 May 2004 14:36:43 -0300 (ADT) +Received: from tht.net (vista.tht.net [216.126.88.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F40AD1F1C1 + for ; + Wed, 5 May 2004 14:31:59 -0300 (ADT) +Received: from [134.22.70.11] (dyn-70-11.tor.dsl.tht.net [134.22.70.11]) + by tht.net (Postfix) with ESMTP + id 4AB1B76B38; Wed, 5 May 2004 13:32:02 -0400 (EDT) +Subject: Re: LIKE and INDEX +From: Rod Taylor +To: Jie Liang +Cc: Postgresql Performance +In-Reply-To: +References: +Content-Type: text/plain +Message-Id: <1083778304.60668.3.camel@jester> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.5 +Date: Wed, 05 May 2004 13:31:45 -0400 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/41 +X-Sequence-Number: 6872 + +> but if I use: +> select url from urlinfo where url like 'http://%.lycos.de'; +> it won't use index at all, NOT good! +> is there any way I can force secon query use index??? + +create index nowww on urlinfo(replace(replace(url, 'http://', ''), +'www.', ''))); + +SELECT url + FROM urlinfo +WHERE replace(replace(url, 'http://', ''), 'www.', '') = 'lycos.de' + AND url LIKE 'http://%.lycos.de' ; + +The replace() will narrow the search down to all records containing +lycos.de. Feel free to write a more complex alternative for replace() +that will deal with more than just optional www. + +Once the results have been narrowed down, you may use the original like +expression to confirm it is your record. + + +From pgsql-performance-owner@postgresql.org Wed May 5 15:31:25 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP + id 9F620D1F189; Wed, 5 May 2004 15:13:01 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 76287-04; Wed, 5 May 2004 15:12:41 -0300 (ADT) +Received: from anchor-post-35.mail.demon.net (anchor-post-35.mail.demon.net + [194.217.242.85]) by svr1.postgresql.org (Postfix) with ESMTP + id ACF3AD1E838; Wed, 5 May 2004 15:12:39 -0300 (ADT) +Received: from mwynhau.demon.co.uk ([193.237.186.96] + helo=mainbox.archonet.com) + by anchor-post-35.mail.demon.net with esmtp (Exim 3.35 #1) + id 1BLQsp-000Ihn-0Z; Wed, 05 May 2004 19:12:39 +0100 +Received: from [192.168.1.17] (client17.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP + id CED651705E; Wed, 5 May 2004 19:12:37 +0100 (BST) +Message-ID: <40992E96.5090301@archonet.com> +Date: Wed, 05 May 2004 19:12:38 +0100 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 0.6 (X11/20040502) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Jie Liang +Cc: pgsql@postgresql.org, pgsql-performance@postgresql.org +Subject: Re: LIKE and INDEX +References: +In-Reply-To: +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/40 +X-Sequence-Number: 6871 + +Jie Liang wrote: +> All, +> This is old topic, when I use: +> select url from urlinfo where url like 'http://www.lycos.de%'; +> it uses the index, good! +> +> but if I use: +> select url from urlinfo where url like 'http://%.lycos.de'; +> it won't use index at all, NOT good! +> is there any way I can force secon query use index??? + +I've seen people define a reverse(text) function via plperl or similar +then build a functional index on reverse(url). Of course, that would +rely on your knowing which end of your search pattern has the % wildcard. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Wed May 5 15:27:37 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 6917AD1F151 + for ; + Wed, 5 May 2004 15:13:35 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 73511-06 + for ; + Wed, 5 May 2004 15:13:15 -0300 (ADT) +Received: from monsoon.he.net (monsoon.he.net [64.62.221.2]) + by svr1.postgresql.org (Postfix) with SMTP id 540F6D1E856 + for ; + Wed, 5 May 2004 15:13:13 -0300 (ADT) +Received: from [10.244.45.7] ([216.113.168.128]) by monsoon.he.net for + ; Wed, 5 May 2004 11:13:06 -0700 +In-Reply-To: <24916.1083762195@sss.pgh.pa.us> +References: <47E18B2A3472@3months.com> <24916.1083762195@sss.pgh.pa.us> +Mime-Version: 1.0 (Apple Message framework v613) +Content-Type: text/plain; charset=US-ASCII; format=flowed +Message-Id: +Content-Transfer-Encoding: 7bit +Cc: Tom Lane , pgsql-performance@postgresql.org +From: Paul Tuckfield +Subject: Re: very high CPU usage in "top", but not in "mpstat" +Date: Wed, 5 May 2004 11:13:11 -0700 +To: Cyrille Bonnet +X-Mailer: Apple Mail (2.613) +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/39 +X-Sequence-Number: 6870 + +I'm guessing you have a 4 cpu box: +1 99 percent busy process on a 4 way box == about 25% busy overall. + + +On May 5, 2004, at 6:03 AM, Tom Lane wrote: + +> "Cyrille Bonnet" writes: +>> Should I be worried that Postgres is eating up 99% of my CPU??? Or is +>> this +>> *expected* behaviour? +> +> It's not expected, unless you are running some very long-running query. +> +> The conflict between what top says and what mpstat says is strange; I +> wonder if you might have a buggy version of one of them? You should +> probably check some other tools (try "vmstat 1" for instance) to see if +> you can get a consensus on whether the CPU is maxed out or not ... +> +> regards, tom lane +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 8: explain analyze is your friend +> + + +From pgsql-performance-owner@postgresql.org Wed May 5 18:11:49 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 3A40ED1E900 + for ; + Wed, 5 May 2004 18:11:48 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 50709-08 + for ; + Wed, 5 May 2004 18:11:30 -0300 (ADT) +Received: from mx1.neopolitan.us (mx1.neopolitan.us [65.87.16.224]) + by svr1.postgresql.org (Postfix) with ESMTP id 63A1DD1DC64 + for ; + Wed, 5 May 2004 18:11:27 -0300 (ADT) +Received: from [65.87.16.98] (HELO [10.0.0.210]) + by mx1.neopolitan.us (CommuniGate Pro SMTP 4.1.8) + with ESMTP-TLS id 4156961; Wed, 05 May 2004 14:11:29 -0700 +Subject: Re: [OFF-TOPIC] - Known maximum size of the PostgreSQL +From: "J. Andrew Rogers" +To: Carlos Eduardo Smanioto +Cc: pgsql-performance@postgresql.org +In-Reply-To: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> +References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> +Content-Type: text/plain +Organization: +Message-Id: <1083791489.11496.23.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) +Date: 05 May 2004 14:11:29 -0700 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/43 +X-Sequence-Number: 6874 + +On Sat, 2004-06-05 at 11:55, Carlos Eduardo Smanioto wrote: +> What's the case of bigger database PostgreSQL (so greate and amount of +> registers) that they know??? + + +You might want to fix the month on your system time. + +With respect to how big PostgreSQL databases can get in practice, these +are our two biggest implementations: + +- 0.5 Tb GIS database (this maybe upwards of 600-700Gb now, I didn't +check) + +- 10 Gb OLTP system with 70 million rows and a typical working set of +2-3 Gb. + + +Postgres is definitely capable of handling large pretty databases with +ease. There are some narrow types of workloads that it doesn't do so +well on, but for many normal DBMS loads it scales quite well. + + +j. andrew rogers + + + +From pgsql-performance-owner@postgresql.org Wed May 5 18:23:18 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id E14E0D1E791 + for ; + Wed, 5 May 2004 18:23:15 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 59171-03 + for ; + Wed, 5 May 2004 18:22:57 -0300 (ADT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by svr1.postgresql.org (Postfix) with ESMTP id 1878BD1F1EC + for ; + Wed, 5 May 2004 18:22:55 -0300 (ADT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.10/8.12.10) with ESMTP id i45LMgN6018540; + Wed, 5 May 2004 15:22:43 -0600 (MDT) +Date: Wed, 5 May 2004 15:23:03 -0600 (MDT) +From: "scott.marlowe" +To: Carlos Eduardo Smanioto +Cc: +Subject: Re: [OFF-TOPIC] - Known maximum size of the PostgreSQL +In-Reply-To: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-IHS-MailScanner: Found to be clean +X-IHS-MailScanner-SpamCheck: +X-IHS-MailScanner-Envelope-Sender: scott.marlowe@ihs.com +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/44 +X-Sequence-Number: 6875 + +On Sat, 5 Jun 2004, Carlos Eduardo Smanioto wrote: + +> Hello all, +> +> What's the case of bigger database PostgreSQL (so greate and amount of +> registers) that they know??? + +http://www.postgresql.org/docs/faqs/FAQ.html#4.5 + + +From pgsql-performance-owner@postgresql.org Wed May 5 22:39:41 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 45181D1F240 + for ; + Wed, 5 May 2004 22:39:40 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 40286-02 + for ; + Wed, 5 May 2004 22:39:23 -0300 (ADT) +Received: from houston.familyhealth.com.au (fhnet.arach.net.au + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id 641C3D1F243 + for ; + Wed, 5 May 2004 22:39:18 -0300 (ADT) +Received: from [192.168.0.40] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (8.12.9p1/8.12.9) with ESMTP id + i461dFWL018034; Thu, 6 May 2004 09:39:16 +0800 (WST) + (envelope-from chriskl@familyhealth.com.au) +Message-ID: <4099996E.90903@familyhealth.com.au> +Date: Thu, 06 May 2004 09:48:30 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "J. Andrew Rogers" +Cc: Carlos Eduardo Smanioto , + pgsql-performance@postgresql.org +Subject: Re: [OFF-TOPIC] - Known maximum size of the PostgreSQL +References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> + <1083791489.11496.23.camel@localhost.localdomain> +In-Reply-To: <1083791489.11496.23.camel@localhost.localdomain> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/45 +X-Sequence-Number: 6876 + +>>What's the case of bigger database PostgreSQL (so greate and amount of +>>registers) that they know??? + +Didn't someone say that RedSheriff had a 10TB postgres database or +something? + +Chris + + +From pgsql-performance-owner@postgresql.org Thu May 6 05:13:35 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 1821BD1F268 + for ; + Thu, 6 May 2004 05:13:34 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 50353-05 + for ; + Thu, 6 May 2004 05:13:13 -0300 (ADT) +Received: from anchor-post-33.mail.demon.net (anchor-post-33.mail.demon.net + [194.217.242.91]) + by svr1.postgresql.org (Postfix) with ESMTP id BF0FAD1EA88 + for ; + Thu, 6 May 2004 05:13:11 -0300 (ADT) +Received: from mwynhau.demon.co.uk ([193.237.186.96] + helo=mainbox.archonet.com) + by anchor-post-33.mail.demon.net with esmtp (Exim 3.35 #1) + id 1BLe0F-000G4z-0X; Thu, 06 May 2004 09:13:12 +0100 +Received: from [192.168.1.17] (client17.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP + id EAB04173DC; Thu, 6 May 2004 09:13:09 +0100 (BST) +Message-ID: <4099F396.2020103@archonet.com> +Date: Thu, 06 May 2004 09:13:10 +0100 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 0.6 (X11/20040502) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Christopher Kings-Lynne +Cc: "J. Andrew Rogers" , + Carlos Eduardo Smanioto , + pgsql-performance@postgresql.org +Subject: Re: [OFF-TOPIC] - Known maximum size of the PostgreSQL +References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> + <1083791489.11496.23.camel@localhost.localdomain> + <4099996E.90903@familyhealth.com.au> +In-Reply-To: <4099996E.90903@familyhealth.com.au> +Content-Type: text/plain; charset=windows-1252; format=flowed +Content-Transfer-Encoding: 8bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/46 +X-Sequence-Number: 6877 + +Christopher Kings-Lynne wrote: +>>> What's the case of bigger database PostgreSQL (so greate and amount of +>>> registers) that they know??? +> +> +> Didn't someone say that RedSheriff had a 10TB postgres database or +> something? + + From http://www.redsheriff.com/us/news/news_4_201.html + +"According to the company, RedSheriff processes 10 billion records a +month and the total amount of data managed is more than 32TB. Griffin +said PostgreSQL has been in production for 12 months with not a single +database fault in that time �The stability of the database can not be +questioned. Needless to say, we are extremely happy." + +I think it's safe to assume this is not on a spare Dell 600SC though. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-advocacy-owner@postgresql.org Thu May 6 05:43:55 2004 +X-Original-To: pgsql-advocacy-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP + id 2C845D1F278; Thu, 6 May 2004 05:43:54 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 62277-07; Thu, 6 May 2004 05:43:34 -0300 (ADT) +Received: from frodo.hserus.net (frodo.hserus.net [204.74.68.40]) + by svr1.postgresql.org (Postfix) with ESMTP + id 71EEFD1EA9C; Thu, 6 May 2004 05:43:32 -0300 (ADT) +Received: from concord.pspl.co.in ([202.54.11.72]:61548 helo=frodo.hserus.net) + by frodo.hserus.net with asmtp + (Cipher TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.32 #0) + id 1BLeTd-00081F-1x by authid with plain; + Thu, 06 May 2004 14:13:33 +0530 +Message-ID: <4099FAAD.4040202@frodo.hserus.net> +Date: Thu, 06 May 2004 14:13:25 +0530 +From: Shridhar Daithankar +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.6b) Gecko/20031205 Thunderbird/0.4 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: PostgreSQL Advocacy +Cc: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] [OFF-TOPIC] - Known maximum size of the PostgreSQL +References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> + <1083791489.11496.23.camel@localhost.localdomain> + <4099996E.90903@familyhealth.com.au> + <4099F396.2020103@archonet.com> +In-Reply-To: <4099F396.2020103@archonet.com> +Content-Type: text/plain; charset=windows-1252; format=flowed +Content-Transfer-Encoding: 8bit +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/54 +X-Sequence-Number: 4330 + +Richard Huxton wrote: + +> Christopher Kings-Lynne wrote: +> +>>>> What's the case of bigger database PostgreSQL (so greate and amount of +>>>> registers) that they know??? +>> Didn't someone say that RedSheriff had a 10TB postgres database or +>> something? +> From http://www.redsheriff.com/us/news/news_4_201.html +> +> "According to the company, RedSheriff processes 10 billion records a +> month and the total amount of data managed is more than 32TB. Griffin +> said PostgreSQL has been in production for 12 months with not a single +> database fault in that time �The stability of the database can not be +> questioned. Needless to say, we are extremely happy." +> +> I think it's safe to assume this is not on a spare Dell 600SC though. +> + +I think we should have a case study for that. And publish it on our regular +news/press contacts(Can't imagine the flame war on /...Umm Yummy..:-)). It would +make a lot of noise and gain visibility for us. + +Of course Red Sherrif need to co-operate and spell the details and/or moderate +what we write, but all in all, 32TB database is uber-cool..:-) + + Shridhar + +From pgsql-advocacy-owner@postgresql.org Thu May 6 20:24:28 2004 +X-Original-To: pgsql-advocacy-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP + id A3B7ED1F26B; Thu, 6 May 2004 05:59:39 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 70315-04; Thu, 6 May 2004 05:59:20 -0300 (ADT) +Received: from elbereth.noviforum.si (unknown [193.189.169.66]) + by svr1.postgresql.org (Postfix) with ESMTP + id DC403D1DBA6; Thu, 6 May 2004 05:59:16 -0300 (ADT) +Received: from elbereth.noviforum.si (localhost [127.0.0.1]) + by elbereth.noviforum.si (8.12.10/8.12.10) with ESMTP id i468xEHh004163; + Thu, 6 May 2004 10:59:14 +0200 +Received: (from gregab@localhost) + by elbereth.noviforum.si (8.12.10/8.12.10/Submit) id i468xDe0004162; + Thu, 6 May 2004 10:59:13 +0200 +Date: Thu, 6 May 2004 10:59:13 +0200 +From: Grega Bremec +To: Eduardo Almeida +Cc: Jan Wieck , Josh Berkus , + pgsql-advocacy@postgresql.org, pgsql-performance@postgresql.org +Subject: Re: [PERFORM] MySQL vs PG TPC-H benchmarks +Message-ID: <20040506085913.GA4102@elbereth.noviforum.si> +References: <20040422134249.GA14342@elbereth.noviforum.si> + <20040422135910.24475.qmail@web60607.mail.yahoo.com> +Mime-Version: 1.0 +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; boundary="1yeeQ81UyVL57Vl7" +Content-Disposition: inline +In-Reply-To: <20040422135910.24475.qmail@web60607.mail.yahoo.com> +User-Agent: Mutt/1.4.2i +Organization: Noviforum, Ltd., Software & Media +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests= +X-Spam-Level: +X-Archive-Number: 200405/57 +X-Sequence-Number: 4333 + +--1yeeQ81UyVL57Vl7 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +Content-Transfer-Encoding: quoted-printable + +...and on Thu, Apr 22, 2004 at 06:59:10AM -0700, Eduardo Almeida used the k= +eyboard: + + +> +> To reference, Sun has java 64bits just to IA64 and +> Solaris Sparc 64 not to Opteron. +>=20 + +As I mentioned, that is true for the 1.4.x release of the JVMs. We have been +testing some JCA builds of 1.5.0 on x86_64 so far, but it is too unstable f= +or +any kind of serious work. + +Cheers, +--=20 + Grega Bremec + Senior Administrator + Noviforum Ltd., Software & Media + http://www.noviforum.si/ + +--1yeeQ81UyVL57Vl7 +Content-Type: application/pgp-signature +Content-Disposition: inline + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.3 (GNU/Linux) + +iD8DBQFAmf5hDo/EMYD4+osRAgSLAKCZ2iVm2ygdHbPteedldCOxOeBypgCfR5gm +Hq5CG2qZWLiBIWNlx4k/EMs= +=Etxi +-----END PGP SIGNATURE----- + +--1yeeQ81UyVL57Vl7-- + +From pgsql-performance-owner@postgresql.org Thu May 6 10:46:49 2004 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (unknown [200.46.204.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 579C6D1EAFA + for ; + Thu, 6 May 2004 10:46:48 -0300 (ADT) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024) + with ESMTP id 76415-02 + for ; + Thu, 6 May 2004 10:46:30 -0300 (ADT) +Received: from mta0.beanfield.net (unknown [66.207.192.6]) + by svr1.postgresql.org (Postfix) with ESMTP id D88FBD1B507 + for ; + Thu, 6 May 2004 10:46:25 -0300 (ADT) +Received: from don.webimpact.com (66-207-218-34.beanfield.net [66.207.218.34] + (may be forged)) + by mta0.beanfield.net (8.12.11/8.12.6) with ESMTP id i46DkSKF052436 + for ; + Thu, 6 May 2004 09:46:28 -0400 (EDT) + (envelope-from donv@webimpact.com) +Message-Id: <6.1.0.6.0.20040506094353.01b363c8@localhost> +X-Sender: donv@web-impact.com@localhost +X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 +Date: Thu, 06 May 2004 09:47:08 -0400 +To: pgsql-performance@postgresql.org +From: Don Vaillancourt +Subject: Re: [OFF-TOPIC] - Known maximum size of the +In-Reply-To: <4099F396.2020103@archonet.com> +References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote> + <1083791489.11496.23.camel@localhost.localdomain> + <4099996E.90903@familyhealth.com.au> + <4099F396.2020103@archonet.com> +Mime-Version: 1.0 +Content-Type: multipart/alternative; + boundary="=====================_237368781==.ALT" +X-Virus-Scanned: by amavisd-new at postgresql.org +X-Spam-Status: No, hits=0.7 tagged_above=0.0 required=5.0 tests=HTML_20_30, + HTML_FONTCOLOR_BLUE, HTML_FONT_BIG, HTML_MESSAGE +X-Spam-Level: +X-Archive-Number: 200405/49 +X-Sequence-Number: 6880 + +--=====================_237368781==.ALT +Content-Type: text/plain; charset="us-ascii"; format=flowed + + +Here's a question a little off-topic. + +What would a 32TB database hardware configuration look like. I'm assuming +200GB hard-drives which would total 160 of them. Double that if you mirror +them. + +Am I correct? + +At 04:13 AM 06/05/2004, you wrote: +>Christopher Kings-Lynne wrote: +>>>>What's the case of bigger database PostgreSQL (so greate and amount of +>>>>registers) that they know??? +>> +>>Didn't someone say that RedSheriff had a 10TB postgres database or something? +> +> From http://www.redsheriff.com/us/news/news_4_201.html +> +>"According to the company, RedSheriff processes 10 billion records a month +>and the total amount of data managed is more than 32TB. Griffin said +>PostgreSQL has been in production for 12 months with not a single database +>fault in that time "The stability of the database can not be questioned. +>Needless to say, we are extremely happy." +> +>I think it's safe to assume this is not on a spare Dell 600SC though. +> +>-- +> Richard Huxton +> Archonet Ltd +> +>---------------------------(end of broadcast)--------------------------- +>TIP 7: don't forget to increase your free space map settings + +Don Vaillancourt +Director of Software Development + +WEB IMPACT INC. +416-815-2000 ext. 245 +email: donv@webimpact.com +web: http://www.webimpact.com + + + +This email message is intended only for the addressee(s) +and contains information that may be confidential and/or +copyright. If you are not the intended recipient please +notify the sender by reply email and immediately delete +this email. Use, disclosure or reproduction of this email +by anyone other than the intended recipient(s) is strictly +prohibited. No representation is made that this email or +any attachments are free of viruses. Virus scanning is +recommended and is the responsibility of the recipient. + + + + + + + + + + + +--=====================_237368781==.ALT +Content-Type: text/html; charset="us-ascii" + + + +
+Here's a question a little off-topic.

+What would a 32TB database hardware configuration look like.  I'm +assuming 200GB hard-drives which would total 160 of them.  Double +that if you mirror them.

+Am I correct?

+At 04:13 AM 06/05/2004, you wrote:
+
Christopher Kings-Lynne +wrote:
+
What's +the case of bigger database PostgreSQL (so greate and amount of
+registers) that they know???

+Didn't someone say that RedSheriff had a 10TB postgres database or +something?

+ From +http://www.redsheriff.com/us/news/news_4_201.html

+"According to the company, RedSheriff processes 10 billion records a +month and the total amount of data managed is more than 32TB. Griffin +said PostgreSQL has been in production for 12 months with not a single +database fault in that time �The stability of the database can not be +questioned. Needless to say, we are extremely happy."

+I think it's safe to assume this is not on a spare Dell 600SC +though.

+--
+  Richard Huxton
+  Archonet Ltd

+---------------------------(end of +broadcast)---------------------------
+TIP 7: don't forget to increase your free space map +settings
+

+Don +Vaillancourt
+Director +of Software Development

+WEB +IMPACT INC.
+416-815-2000 +ext. 245
+email: donv@webimpact.com
+web: +http://www.webimpact.com +

+

+

This email message is intended only for the addressee(s) 
+and contains information that may be confidential and/or 
+copyright.  If you are not the intended recipient please 
+notify the sender by reply email and immediately delete 
+this email. Use, disclosure or reproduction of this email 
+by anyone other than the intended recipient(s) is strictly 
+prohibited. No representation is made that this email or 
+any attachments are free of viruses. Virus scanning is 
+recommended and is the responsibility of the recipient.
+
+
+
+
+
+
+
+
+
+
+
+
+--=====================_237368781==.ALT--
+
+
+From pgsql-performance-owner@postgresql.org  Thu May  6 12:45:10 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 89DA8D1F2E1
+	for ;
+	Thu,  6 May 2004 12:45:09 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
+	by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024)
+	with ESMTP id 22973-07
+	for ;
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+	[216.136.174.143])
+	by svr1.postgresql.org (Postfix) with SMTP id B5A4AD1F2C9
+	for ;
+	Thu,  6 May 2004 12:44:44 -0300 (ADT)
+Message-ID: <20040506154443.82425.qmail@web13125.mail.yahoo.com>
+Received: from [63.78.248.48] by web13125.mail.yahoo.com via HTTP;
+	Thu, 06 May 2004 08:44:43 PDT
+Date: Thu, 6 May 2004 08:44:43 -0700 (PDT)
+From: Litao Wu 
+Subject: Re: pg_stat
+To: Litao Wu , pgsql-performance@postgresql.org
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/50
+X-Sequence-Number: 6881
+
+All,
+
+Since I have not seen any follow up post,
+I am wondering if my question is not clear or
+what.
+
+Anyway, my postgres version is 7.3.2, and I
+want to know:
+1. How to determine if some of indexes are used by
+any queries, like Oracle's:
+alter index my_index monitoring usage
+2. The relationship between 
+"number of index scans done" and 
+"Number of disk block fetch requests for index"
+as shown in the query.
+
+Thank you!
+ 
+--- Litao Wu  wrote:
+> Hi,
+> 
+> I have query:
+> select pg_stat_get_numscans(76529669),
+> pg_stat_get_blocks_fetched(76529669), 
+> pg_stat_get_blocks_hit(76529669);
+> 
+> The result is:
+>  pg_stat_get_numscans | pg_stat_get_blocks_fetched |
+> pg_stat_get_blocks_hit
+>
+----------------------+----------------------------+------------------------
+>                     0 |                      23617 |
+>  
+>                23595
+> (1 row)
+> 
+> My questions are:
+> 1. How can index disk blocks be requested (either 
+> from disk or cache) without index scan?
+> 2. If I want to check if an index is used after 
+> pg_stat_reset(), how can I get it? By number of
+> scans
+> or block requests, or some other ways?
+> 
+> Thanks,
+> 
+> 
+> 	
+> 		
+> __________________________________
+> Do you Yahoo!?
+> Win a $20,000 Career Makeover at Yahoo! HotJobs  
+> http://hotjobs.sweepstakes.yahoo.com/careermakeover 
+> 
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+Win a $20,000 Career Makeover at Yahoo! HotJobs  
+http://hotjobs.sweepstakes.yahoo.com/careermakeover 
+
+From pgsql-performance-owner@postgresql.org  Thu May  6 15:11:02 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+	by mainbox.archonet.com (Postfix) with ESMTP
+	id 21065167FA; Thu,  6 May 2004 19:10:39 +0100 (BST)
+Message-ID: <409A7FA0.50704@archonet.com>
+Date: Thu, 06 May 2004 19:10:40 +0100
+From: Richard Huxton 
+User-Agent: Mozilla Thunderbird 0.6 (X11/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: =?ISO-8859-1?Q?Pailloncy_Jean-G=E9rard?= 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: INSERT RULE
+References: 
+	
+In-Reply-To: 
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+Content-Transfer-Encoding: 8bit
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Pailloncy Jean-G�rard wrote:
+>> I try to do:
+>> CREATE RULE ndicti AS ON INSERT TO ndict
+>>     DO INSTEAD INSERT INTO 'ndict_' || (NEW.word_id & 255)
+>>     VALUES( NEW.url_id, NEW.word_id, NEW.intag);
+>> I got an error on 'ndict_' .
+>> I did not found the right syntax.
+> 
+> In fact I discover that
+> SELECT * FROM / INSERT INTO table
+> doesn't accept function that returns the name of the table as table, but 
+> only function that returns rows....
+> 
+> I'm dead.
+> 
+> Does this feature, is possible or plan ?
+> Is there a trick to do it ?
+
+You could call a plpgsql function and inside that use EXECUTE (or use 
+pltcl or some other interpreted language).
+
+Not sure what you're doing will help you much though. Are you aware that 
+you can have partial indexes?
+
+CREATE INDEX i123 ON ndict WHERE (word_id & 255)=123;
+
+That might be what you're after, but it's difficult to be sure without 
+knowing what problem you're trying to solve.
+-- 
+   Richard Huxton
+   Archonet Ltd
+
+From pgsql-advocacy-owner@postgresql.org  Thu May  6 19:30:10 2004
+X-Original-To: pgsql-advocacy-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP
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+	Fri, 7 May 2004 08:29:11 +1000
+Date: Fri, 7 May 2004 08:29:11 +1000 (EST)
+From: Gavin Sherry 
+To: Shridhar Daithankar 
+Cc: PostgreSQL Advocacy ,
+	pgsql-performance@postgresql.org
+Subject: Re: [PERFORM] [OFF-TOPIC] - Known maximum size of
+In-Reply-To: <4099FAAD.4040202@frodo.hserus.net>
+Message-ID: 
+References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote>
+	<1083791489.11496.23.camel@localhost.localdomain>
+	<4099996E.90903@familyhealth.com.au>
+	<4099F396.2020103@archonet.com> <4099FAAD.4040202@frodo.hserus.net>
+MIME-Version: 1.0
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+
+On Thu, 6 May 2004, Shridhar Daithankar wrote:
+
+> Richard Huxton wrote:
+>
+> > Christopher Kings-Lynne wrote:
+> >
+> >>>> What's the case of bigger database PostgreSQL (so greate and amount =
+of
+> >>>> registers) that they know???
+> >> Didn't someone say that RedSheriff had a 10TB postgres database or
+> >> something?
+> >  From http://www.redsheriff.com/us/news/news_4_201.html
+> >
+> > "According to the company, RedSheriff processes 10 billion records a
+> > month and the total amount of data managed is more than 32TB. Griffin
+> > said PostgreSQL has been in production for 12 months with not a single
+> > database fault in that time =93The stability of the database can not be
+> > questioned. Needless to say, we are extremely happy."
+> >
+> > I think it's safe to assume this is not on a spare Dell 600SC though.
+> >
+>
+> I think we should have a case study for that. And publish it on our regul=
+ar
+> news/press contacts(Can't imagine the flame war on /...Umm Yummy..:-)). I=
+t would
+> make a lot of noise and gain visibility for us.
+>
+> Of course Red Sherrif need to co-operate and spell the details and/or mod=
+erate
+> what we write, but all in all, 32TB database is uber-cool..:-)
+
+I've tried contacting them. They will not return my phone calls or emails.
+
+Gavin
+
+From pgsql-performance-owner@postgresql.org  Fri May  7 07:58:04 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ; Fri, 7 May 2004 18:54:40 +0800
+Message-Id: <200405071054.i47Asbh9012448@mail.census.gov.ph>
+From: "Michael Ryan S. Puncia" 
+To: 
+Subject: Help how to tune-up my Database
+Date: Fri, 7 May 2004 19:07:23 +0800
+MIME-Version: 1.0
+Content-Type: multipart/alternative;
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+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0000_01C43466.878B7A30
+Content-Type: text/plain;
+	charset="us-ascii"
+Content-Transfer-Encoding: 7bit
+
+Hi,
+
+            I am a newbie here and just starting to use postgresql. My
+problems is how to tune up my server because it its too slow.
+
+We just ported from DBF to postgresql.
+
+ 
+
+This is my PC specs: P4, 512Ram, Linux 9
+
+ 
+
+Because I am working in a statistical organization we have a very large data
+volume
+
+These are my data:
+
+ 
+
+Table 1 with 60 million data but only with 10 fields
+
+Table 2 with 30 million data with 15 fields
+
+Table 3 with 30 million data with 10 fields
+
+ 
+
+I will only use this server for querying ... I already read and apply those
+articles found in the archives section but still the performance is not
+good.
+
+I am planning to add another 512 RAM .Another question is how to calculate
+shared_buffer size ..
+
+ 
+
+Thanks a lot and hoping for your kind answers ..
+
+ 
+
+Michael Puncia
+
+Philippines
+
+ 
+
+ 
+
+ 
+
+ 
+
+                                   
+
+ 
+
+
+------=_NextPart_000_0000_01C43466.878B7A30
+Content-Type: text/html;
+	charset="us-ascii"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+

+
+
Hi,

+
+
         &n=
+bsp;  I
+am a newbie here and just starting to use postgresql. My problems is how to
+tune up my server because it its too slow.

+
+
We just ported from DBF to postgresql.=
+

+
+
 

+
+
This is my PC specs: P4, 512Ram, Linux 9

+
+
 

+
+
Because I am working in a statistical organization we ha=
+ve a
+very large data volume

+
+
These are my data:

+
+
 

+
+
Table 1 with 60 million data but only with 10 fields

+
+
Table 2 with 30 million data with 15 fields

+
+
Table 3 with 30 million data with 10 fields

+
+
 

+
+
I will only use this server for querying ….. I alr=
+eady
+read and apply those articles found in the archives section but still the
+performance is not good.

+
+
I am planning to add another 512 RAM …Another ques=
+tion
+is how to calculate shared_buffer size ..

+
+
 

+
+
Thanks a lot and hoping for your kind answers ..

+
+
 

+
+
Michael Puncia

+
+
=
+Philippines

+
+
 

+
+
 

+
+
 

+
+
 

+
+
         &n=
+bsp;            =
+;            
+

+
+
 

+
+

+
+
+
+
+
+------=_NextPart_000_0000_01C43466.878B7A30--
+
+
+
+From pgsql-performance-owner@postgresql.org  Fri May  7 13:01:19 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+	Fri, 7 May 2004 09:59:45 -0600 (MDT)
+Date: Fri, 7 May 2004 10:00:03 -0600 (MDT)
+From: "scott.marlowe" 
+To: "Michael Ryan S. Puncia" 
+Cc: 
+Subject: Re: Help how to tune-up my Database
+In-Reply-To: <200405071054.i47Asbh9012448@mail.census.gov.ph>
+Message-ID: 
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+
+On Fri, 7 May 2004, Michael Ryan S. Puncia wrote:
+
+> Hi,
+> 
+>             I am a newbie here and just starting to use postgresql. My
+> problems is how to tune up my server because it its too slow.
+
+First, read this:
+
+http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+
+> This is my PC specs: P4, 512Ram, Linux 9
+
+get more ram.
+
+Hard Drives:  interface, how many, RAID???
+
+For a mostly read database IDEs are pretty good.  Having multiple drives 
+in a RAID-5 or RAID1+0 works well on a mostly read database too.  Keep the 
+stripe size small is setting up a RAID array for a database.
+
+> Because I am working in a statistical organization we have a very large data
+> volume
+> 
+> These are my data:
+> 
+>  
+> 
+> Table 1 with 60 million data but only with 10 fields
+> 
+> Table 2 with 30 million data with 15 fields
+> 
+> Table 3 with 30 million data with 10 fields
+
+That's not really that big, but it's big enough you have to make sure your 
+server is tuned properly.
+
+> I will only use this server for querying ... I already read and apply those
+> articles found in the archives section but still the performance is not
+> good.
+> 
+> I am planning to add another 512 RAM .Another question is how to calculate
+> shared_buffer size ..
+
+I'm assuming you've recently vacuumed full and analyzed your database...
+
+Shared buffers should probably be between 1000 and 10000 on about 98% of 
+all installations.  Setting it higher than 25% of memory is usually a bad 
+idea.  Since they're in 8k blocks (unless you compiled with a customer 
+block size, you'd know if you did, it's not something you can accidentally 
+do by leaning on the wrong switch...) you probably want about 10000 blocks 
+or so to start, which will give you about 80 megs of shared buffer.
+
+PostgreSQL doesn't really cache as well as the kernel, so it's better to 
+leave more memory available for kernel cache than you allocate to buffer 
+cache.  On a machine with only 512Meg, I'm guessing you'll get about 128 
+to 200 megs of kernel cache if you're only running postgresql and you have 
+it set to 10000 buffers.
+
+The important things to check / set are things lik effective_cache_size.  
+It too is measured in 8k blocks, and reflects the approximate amount of 
+kernel cache being dedicated to postgresql.  assuming a single service 
+postgresql only box, that will be the number that a server that's been up 
+for a while shows under top like so:
+
+  9:50am  up 12:16,  4 users,  load average: 0.00, 0.00, 0.00                                       
+104 processes: 102 sleeping, 2 running, 0 zombie, 0 stopped
+CPU states:  0.7% user,  0.3% system,  0.0% nice,  1.7% idle
+Mem:   512924K av,  499248K used,   13676K free,       0K shrd,   54856K buff
+Swap: 2048248K av,    5860K used, 2042388K free                  229572K cached
+
+the 229572k cached entry shows about 230 megs.  divided by 8192 we get 
+about 28000.
+
+sort_mem might do with a small bump, especially if you're only handling a 
+few connections at a time.  Be careful, it's per sort, and measured in 
+megs, so it's easy for folks to set it too high and make their machine 
+start flushing too much kernel cache, which will slow down the other 
+backends that have to go to disk for data.
+
+A good starting point for testing is anywhere from 8192 to 32768.  32768 
+is 32 megs, which can starve a machine as small as yours if there are a 
+couple of queries each running a couple of sorts on large sets at the same 
+time.
+
+Lastly, using explain analyze  you can see if postgresql 
+is making a bad plan choice.  compared estimated rows to actual rows.  
+Look for things like nested loops being run on what the planner thinks 
+will be 80 rows but is, in fact, 8000 rows.
+
+You can change random page cost to change the tendency of the server to 
+favor seq scans to index scans.  Lower = greater tendency towards index 
+scans.  the default is 4, but most production servers with enough memory 
+to cache most of their data will run well on a setting of 1.2 to 1.4.  My 
+dual 2800 with 2 gig ram runs quite well at 1.3 to 1.4. 
+
+You can also change the settings to random_page_cost, as well as turning 
+off options to the planner with the following env vars:
+
+enable_hashagg
+enable_hashjoin
+enable_indexscan
+enable_mergejoin
+enable_nestloop
+enable_seqscan
+enable_sort
+enable_tidscan
+
+They are all on by default, and shouldn't really be turned off by default 
+for the most part.  but for an individual session to figure out if the 
+query planner is making the right plan you can set them to off to see if 
+using another plan works better.  
+
+so, if you've got a nested loop running over 80000 rows that the planner 
+thought was gonna be 80 rows, you can force it to stop using the nested 
+loop for your session with:
+
+set enable_nestloop=off;
+
+and use explain analyze to see if it runs faster.
+
+You can set effective_cache_size and sort_mem on the fly for a single 
+connection, or set them in postgresql.conf and restart or reload to make a 
+change in the default.
+
+shared_buffers is set on postgresql startup, and can't be changed without 
+restarting the database.  Reloading won't do it.
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 16:49:53 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Subject: Re: Help how to tune-up my Database
+References: <200405071054.i47Asbh9012448@mail.census.gov.ph>
+	
+In-Reply-To: 
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+Date: Fri, 07 May 2004 16:47:09 GMT
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+
+scott.marlowe wrote:
+> sort_mem might do with a small bump, especially if you're only handling a 
+> few connections at a time.  Be careful, it's per sort, and measured in 
+> megs, so it's easy for folks to set it too high and make their machine 
+> start flushing too much kernel cache, which will slow down the other 
+> backends that have to go to disk for data.
+
+http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html
+(under "Memory"), it says that sort_mem is set in KB. Is this document 
+wrong (or outdated)?
+
+From pgsql-performance-owner@postgresql.org  Fri May  7 20:47:11 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for pgsql-performance@postgresql.org; Fri, 7 May 2004 23:35:53 GMT
+From: Gaetano Mendola 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: [OFF-TOPIC] - Known maximum size of the
+Date: Sat, 08 May 2004 01:35:44 +0200
+Organization: PYRENET Midi-pyrenees Provider
+Lines: 25
+Message-ID: <409C1D50.4010602@bigfoot.com>
+References: <034d01c44b2e$ae9b2b00$cf00a8c0@smannote>
+	<1083791489.11496.23.camel@localhost.localdomain>
+	<4099996E.90903@familyhealth.com.au>
+	<4099F396.2020103@archonet.com>
+	<6.1.0.6.0.20040506094353.01b363c8@localhost>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii; format=flowed
+Content-Transfer-Encoding: 7bit
+X-Complaints-To: abuse@pyrenet.fr
+To: Don Vaillancourt 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+In-Reply-To: <6.1.0.6.0.20040506094353.01b363c8@localhost>
+To: pgsql-performance@postgresql.org
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+X-Sequence-Number: 6886
+
+Don Vaillancourt wrote:
+
+> 
+> Here's a question a little off-topic.
+> 
+> What would a 32TB database hardware configuration look like.  I'm 
+> assuming 200GB hard-drives which would total 160 of them.  Double that 
+> if you mirror them.
+> 
+> Am I correct?
+
+Why do you have to mirror them ? Usually a SAN make data redundancy
+using a RAID 4 or 5, this depend if you need read performances or
+write performances, in the case of Red Sherif I guess that guys are
+using RAID 50 ( 0 + 5 ) sets so what you "waste" is a disk for each
+set.
+
+
+
+Regards
+Gaetano Mendola
+
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 11:00:13 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <00b901c43697$333ec5d0$5f00a8c0@suport01>
+From: "Anderson Boechat Lopes" 
+To: 
+Subject: Why queries takes too much time to execute?
+Date: Mon, 10 May 2004 11:00:43 -0300
+MIME-Version: 1.0
+Content-Type: multipart/alternative;
+	boundary="----=_NextPart_000_00B6_01C4367E.0A0A8FA0"
+X-Priority: 3
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+X-Mailer: Microsoft Outlook Express 6.00.2800.1106
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+	HTML_MESSAGE
+X-Spam-Level: 
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+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_00B6_01C4367E.0A0A8FA0
+Content-Type: text/plain;
+	charset="iso-8859-1"
+Content-Transfer-Encoding: quoted-printable
+
+    Hi.
+
+    I=B4m new here and i=B4m not sure if this is the right email to solve m=
+y problem.
+
+    Well, i have a very large database, with vary tables and very registers=
+. Every day, too many operations are perfomed in that DB, with queries that=
+ insert, delete and update. Once a week some statistics are collected using=
+ vacuum analyze.
+=20=20=20=20
+    The problem is after a period of time (one month, i think), the queries=
+ takes too much time to perform. A simple update can take 10 seconds or mor=
+e to perform.
+
+    If i make a backup, drop and recreate the DB, everything goes back norm=
+al.
+
+    Could anyone give me any guidance?
+------=_NextPart_000_00B6_01C4367E.0A0A8FA0
+Content-Type: text/html;
+	charset="iso-8859-1"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+
+
+
    Hi.

+
 

+
    I=B4m n=
+ew here and=20
+i=B4m not sure if this is the right email to solve my problem.

+
 

+
    Well, i=
+ have a=20
+very large database, with vary tables and very registers. Every day, t=
+oo=20
+many operations are perfomed in that DB, with queries that insert, delete a=
+nd=20
+update. Once a week some statistics are collected using vacuum=20
+analyze.

+
    =
+

+
    The pro=
+blem is=20
+after a period of time (one month, i think), the queries takes too muc=
+h=20
+time to perform. A simple update can take 10 seconds or more to=20
+perform.

+
 

+
    If i ma=
+ke a=20
+backup, drop and recreate the DB, everything goes back=20
+normal.

+
 

+
    Could=
+=20
+anyone give me any guidance?

+
+------=_NextPart_000_00B6_01C4367E.0A0A8FA0--
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 11:22:09 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 10 May 2004 19:51:50 +0530
+Message-ID: <409F8FFB.1010708@frodo.hserus.net>
+Date: Mon, 10 May 2004 19:51:47 +0530
+From: Shridhar Daithankar 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.6b) Gecko/20031205 Thunderbird/0.4
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Anderson Boechat Lopes 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Why queries takes too much time to execute?
+References: <00b901c43697$333ec5d0$5f00a8c0@suport01>
+In-Reply-To: <00b901c43697$333ec5d0$5f00a8c0@suport01>
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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+X-Spam-Level: 
+X-Archive-Number: 200405/57
+X-Sequence-Number: 6888
+
+Anderson Boechat Lopes wrote:
+>     Hi.
+>  
+>     I�m new here and i�m not sure if this is the right email to solve my 
+> problem.
+>  
+>     Well, i have a very large database, with vary tables and very 
+> registers. Every day, too many operations are perfomed in that DB, with 
+> queries that insert, delete and update. Once a week some statistics are 
+> collected using vacuum analyze.
+
+i guess you need to run it much more frequently than that. Thought you haven't 
+given actual size of data etc., once or twice per day should be much better.
+>    
+>     The problem is after a period of time (one month, i think), the 
+> queries takes too much time to perform. A simple update can take 10 
+> seconds or more to perform.
+
+You need to vacuum full once in a while and setup FSM parameters correctly.
+>  
+>     If i make a backup, drop and recreate the DB, everything goes back 
+> normal.
+>  
+>     Could anyone give me any guidance?
+
+Check following for basic performance tuning
+
+http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html
+
+HTH
+
+  Shridhar
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 11:24:41 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <409F9098.20700@familyhealth.com.au>
+Date: Mon, 10 May 2004 22:24:24 +0800
+From: Christopher Kings-Lynne 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Anderson Boechat Lopes 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Why queries takes too much time to execute?
+References: <00b901c43697$333ec5d0$5f00a8c0@suport01>
+In-Reply-To: <00b901c43697$333ec5d0$5f00a8c0@suport01>
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+
+>     Well, i have a very large database, with vary tables and very 
+> registers. Every day, too many operations are perfomed in that DB, with 
+> queries that insert, delete and update. Once a week some statistics are 
+> collected using vacuum analyze.
+
+Have vacuum analyze running once an HOUR if it's very busy.  If you are 
+using 7.4, run the pg_autovacuum daemon that's in contrib/pg_autovacuum.
+
+>     The problem is after a period of time (one month, i think), the 
+> queries takes too much time to perform. A simple update can take 10 
+> seconds or more to perform.
+
+If running vacuum analyze once an hour doesn't help, try running a 
+vacuum full once a week or something to fix the problem.
+
+Also, try upgrading to 7.4 which has indexes that won't suffer from bloat.
+
+Chris
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 14:36:15 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 3721DD1B179
+	for ;
+	Mon, 10 May 2004 14:36:14 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
+	by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024)
+	with ESMTP id 26290-06
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+	for ;
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+Message-ID: <00d401c436b5$5b03e960$5f00a8c0@suport01>
+From: "Anderson Boechat Lopes" 
+To: 
+References: <00b901c43697$333ec5d0$5f00a8c0@suport01>
+	<409F8FFB.1010708@frodo.hserus.net>
+Subject: Re: Why queries takes too much time to execute?
+Date: Mon, 10 May 2004 14:36:39 -0300
+MIME-Version: 1.0
+Content-Type: text/plain;
+	charset="iso-8859-1"
+Content-Transfer-Encoding: 8bit
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+X-Spam-Level: 
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+X-Sequence-Number: 6890
+
+    Hum... now i think i�m beginning to understand.
+
+    The vacuum analyse is recommended to perform at least every day, after
+adding or deleting a large number of records, and not vacuum full analyse.
+I�ve performed the vacuum full analyse every day and after some time i�ve
+noticed the database was corrupted. I couldn�t select anything any more.
+    Do you think if i perform vacuum analyse once a day and perform vacuum
+full analyse once a week, i will get to fix this problem?
+
+    Thanks for help me, folks.
+
+    PS: Sorry for my grammar mistakes. My writting is not so good. :)
+
+
+----- Original Message -----
+From: "Shridhar Daithankar" 
+To: "Anderson Boechat Lopes" 
+Cc: 
+Sent: Monday, May 10, 2004 11:21 AM
+Subject: Re: [PERFORM] Why queries takes too much time to execute?
+
+
+> Anderson Boechat Lopes wrote:
+> >     Hi.
+> >
+> >     I�m new here and i�m not sure if this is the right email to solve my
+> > problem.
+> >
+> >     Well, i have a very large database, with vary tables and very
+> > registers. Every day, too many operations are perfomed in that DB, with
+> > queries that insert, delete and update. Once a week some statistics are
+> > collected using vacuum analyze.
+>
+> i guess you need to run it much more frequently than that. Thought you
+haven't
+> given actual size of data etc., once or twice per day should be much
+better.
+> >
+> >     The problem is after a period of time (one month, i think), the
+> > queries takes too much time to perform. A simple update can take 10
+> > seconds or more to perform.
+>
+> You need to vacuum full once in a while and setup FSM parameters
+correctly.
+> >
+> >     If i make a backup, drop and recreate the DB, everything goes back
+> > normal.
+> >
+> >     Could anyone give me any guidance?
+>
+> Check following for basic performance tuning
+>
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html
+>
+> HTH
+>
+>   Shridhar
+>
+>
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 16:17:56 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+From: Chris Browne 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: Why queries takes too much time to execute?
+Date: Mon, 10 May 2004 14:11:21 -0400
+Organization: cbbrowne Computing Inc
+Lines: 43
+Message-ID: <60llk05f06.fsf@dev6.int.libertyrms.info>
+References: <00b901c43697$333ec5d0$5f00a8c0@suport01>
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+X-Sequence-Number: 6893
+
+teouique@terra.com.br ("Anderson Boechat Lopes") writes:
+> ��� I�m new here and i�m not sure if this is the right email to
+> solve my problem.
+
+This should be OK...
+
+> ��� Well, i have a very large database, with vary tables and very
+> registers. Every day,�too many operations are perfomed in that DB,
+> with queries that insert, delete and update.  Once a week some
+> statistics are collected using vacuum analyze.
+>
+> ��� The problem is after�a period of time (one month, i think), the
+> queries takes too much time to perform.�A simple update can take 10
+> seconds or more to perform.
+
+It seems fairly likely that two effects are coming in...
+
+-> The tables that are being updated have lots of dead tuples.
+
+-> The vacuums aren't doing much good because the number of dead
+   tuples is so large that you blow out the FSM (Free Space Map), and
+   thus they can't free up space.
+
+-> Another possibility is that if some tables shrink to small size,
+   and build up to large size (we see this with the _rserv_log_1_
+   and _rserv_log_2_ tables used by the eRServ replication system),
+   the statistics may need to be updated a LOT more often.
+
+You might want to consider running VACUUM a whole lot more often than
+once a week.  If there is any regular time that the system isn't
+terribly busy, you might want to vacuum some or all tables at that
+time.
+
+pg_autovacuum might be helpful; it will automatically do vacuums on
+tables when they have been updated heavily.
+
+There may be more to your problem, but VACUUMing more would allow us
+to get rid of "too many dead tuples around" as a cause.
+-- 
+"cbbrowne","@","acm.org"
+http://cbbrowne.com/info/x.html
+Would-be National Mottos:
+USA: "There oughta' be a law!"
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 15:54:37 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Mon, 10 May 2004 14:52:09 -0400
+From: jao@geophile.com
+To: pgsql-performance@postgresql.org
+Subject: Configuring PostgreSQL to minimize impact of checkpoints
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+My company is developing a PostgreSQL application. We're using 7.3.4
+but will soon upgrade to 7.4.x. Our OS is RedHat 9.  Our production
+machines have 512 MB RAM and IDE disks. So far we've been using
+default configuration settings, but I have started to examine
+performance and to modify these settings.
+
+Our typical transaction involves 5-10 SELECT, INSERT or UPDATEs,
+(usually 1/2 SELECT and the remainder a mixture of INSERT and UPDATE).
+There are a few aggregation queries which need to scan an entire
+table.  We observed highly uneven performance for the small
+transactions. A transaction usually runs in under 100 msec, but we
+would see spikes as high as 40,000 msec. These spikes occurred
+regularly, every 4-5 minutes, and I speculated that checkpointing
+might be the issue.
+
+I created a test case, based on a single table:
+
+        create table test( 
+            id int not null, 
+            count int not null, 
+            filler varchar(200),
+            primary key(id))
+
+I loaded a database with 1,000,000 rows, with the filler column always
+filled with 200 characters.
+
+I then ran a test in which a random row was selected, and the count
+column incremented. Each transaction contained ten such updates. In
+this test, I set 
+
+    shared_buffers = 2000
+    checkpoint_segments = 40
+    checkpoint_timeout = 600
+    wal_debug = 1
+
+I set checkpoint_segments high because I wanted to see whether the
+spikes correlated with checkpoints.
+
+Most transactions completed in under 60 msec. Approximately every 10th
+transaction, the time went up to 500-600 msec, (which is puzzling, but
+not my major concern). I did see a spike every 10 minutes, in which
+transaction time goes up to 5000-8000 msec. The spikes were correlated
+with checkpoint activity, occurring slightly before a log entry that 
+looks like this:
+
+    2004-05-09 16:34:19 LOG:  INSERT @ 2/C2A0F628: prev 2/C2A0F5EC;
+    xprev 0/0; xid 0: XLOG - checkpoint: redo 2/C2984D4C; undo 0/0; 
+    sui 36; xid 1369741; oid 6321782; online
+
+Questions:
+
+1. Can someone provide an overview of checkpoint processing, to help
+me understand the performance issues?
+
+2. Is the spike due to the checkpoint process keeping the disk busy?
+Or is there some locking involved that blocks my application until the
+checkpoint completes?
+
+3. The spikes are quite problematic for us. What can I do to minimize
+the impact of checkpointing on my application? I understand how
+checkpoint_segments and checkpoint_timeout determine when a checkpoint
+occurs; what can I do to lessen the impact of a checkpoint?
+
+4. I understand that a "background writer" is being contemplated for
+7.5.  Will that replace or augment the checkpoint process?  Any
+comments on how that work will apply to my problem would be
+appreciated. I wouldn't mind seeing the average performance,
+(without the spikes) go up -- let's say -- 10%, in exchange for
+more uniform performance. These spikes are a real problem.
+
+Jack Orenstein
+
+----------------------------------------------------------------
+This message was sent using IMP, the Internet Messaging Program.
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 16:10:02 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+From: Bruce Momjian 
+Message-Id: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <1084215129.409fcf597e163@geophile.com>
+To: jao@geophile.com
+Date: Mon, 10 May 2004 15:09:32 -0400 (EDT)
+Cc: pgsql-performance@postgresql.org
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+
+jao@geophile.com wrote:
+> 4. I understand that a "background writer" is being contemplated for
+> 7.5.  Will that replace or augment the checkpoint process?  Any
+> comments on how that work will apply to my problem would be
+> appreciated. I wouldn't mind seeing the average performance,
+> (without the spikes) go up -- let's say -- 10%, in exchange for
+> more uniform performance. These spikes are a real problem.
+
+The background writer is designed to address your specific problem.  We
+will stil checkpoint, but the spike should be greatly minimized.
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 17:00:21 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 10 May 2004 13:59:17 -0600 (MDT)
+Date: Mon, 10 May 2004 13:59:12 -0600 (MDT)
+From: "scott.marlowe" 
+To: Anderson Boechat Lopes 
+Cc: 
+Subject: Re: Why queries takes too much time to execute?
+In-Reply-To: <00d401c436b5$5b03e960$5f00a8c0@suport01>
+Message-ID: 
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+
+On Mon, 10 May 2004, Anderson Boechat Lopes wrote:
+
+>     Hum... now i think i�m beginning to understand.
+> 
+>     The vacuum analyse is recommended to perform at least every day, after
+> adding or deleting a large number of records, and not vacuum full analyse.
+> I�ve performed the vacuum full analyse every day and after some time i�ve
+> noticed the database was corrupted. I couldn�t select anything any more.
+
+Hold it right there, full stop.
+
+If you've got corruption you've either found a rare corner case in 
+postgresql (unlikely, corruption is not usually a big problem for 
+postgresql) OR you have bad hardware.  Test your RAM, CPUs, and hard 
+drives before going any further.   Data corruption, 99% of the time, is 
+not the fault of postgresql but the fault of the hardware.
+
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 17:23:59 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Mon, 10 May 2004 14:23:20 -0600 (MDT)
+From: "scott.marlowe" 
+To: Bricklen 
+Cc: 
+Subject: Re: Help how to tune-up my Database
+In-Reply-To: 
+Message-ID: 
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+
+Sorry about that, I meant kbytes, not megs.  My point being it's NOT 
+measured in 8k blocks, like a lot of other settings.  sorry for the mixup.
+
+On Fri, 7 May 2004, Bricklen wrote:
+
+> scott.marlowe wrote:
+> > sort_mem might do with a small bump, especially if you're only handling a 
+> > few connections at a time.  Be careful, it's per sort, and measured in 
+> > megs, so it's easy for folks to set it too high and make their machine 
+> > start flushing too much kernel cache, which will slow down the other 
+> > backends that have to go to disk for data.
+> 
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html
+> (under "Memory"), it says that sort_mem is set in KB. Is this document 
+> wrong (or outdated)?
+> 
+> ---------------------------(end of broadcast)---------------------------
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+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 15:48:18 2004
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+From: Bricklen 
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+Subject: Re: Help how to tune-up my Database
+References: 
+	
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+Date: Mon, 10 May 2004 20:37:22 GMT
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+
+scott.marlowe wrote:
+
+> Sorry about that, I meant kbytes, not megs.  My point being it's NOT 
+> measured in 8k blocks, like a lot of other settings.  sorry for the mixup.
+> 
+No worries, I just wanted to sort that out for my own benefit, and 
+anyone else who may not have caught that.
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 23:04:55 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <40A03435.7020300@geophile.com>
+Date: Mon, 10 May 2004 22:02:29 -0400
+From: Jack Orenstein 
+User-Agent: Mozilla/4.0 (compatible;MSIE 5.5; Windows 98)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Bruce Momjian 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+References: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+In-Reply-To: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
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+
+Bruce Momjian wrote:
+> jao@geophile.com wrote:
+> 
+>>4. I understand that a "background writer" is being contemplated for
+>>7.5.  Will that replace or augment the checkpoint process?  Any
+>>comments on how that work will apply to my problem would be
+>>appreciated. I wouldn't mind seeing the average performance,
+>>(without the spikes) go up -- let's say -- 10%, in exchange for
+>>more uniform performance. These spikes are a real problem.
+> 
+> 
+> The background writer is designed to address your specific problem.  We
+> will stil checkpoint, but the spike should be greatly minimized.
+> 
+
+Thanks. Do you know when 7.5 is expected to be released?
+
+Until then, is a workaround known? Also, are the delays I'm seeing out of the ordinary?
+I'm looking at one case in which two successive transactions, each updating a handful of
+records, take 26 and 18 *seconds* (not msec) to complete. These transactions normally complete
+in under 30 msec.
+
+Jack Orenstein
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 10 23:34:00 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 10 May 2004 22:33:27 -0400 (EDT)
+From: Bruce Momjian 
+Message-Id: <200405110233.i4B2XRN00185@candle.pha.pa.us>
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <40A03435.7020300@geophile.com>
+To: Jack Orenstein 
+Date: Mon, 10 May 2004 22:33:27 -0400 (EDT)
+Cc: pgsql-performance@postgresql.org
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
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+
+Jack Orenstein wrote:
+> Bruce Momjian wrote:
+> > jao@geophile.com wrote:
+> > 
+> >>4. I understand that a "background writer" is being contemplated for
+> >>7.5.  Will that replace or augment the checkpoint process?  Any
+> >>comments on how that work will apply to my problem would be
+> >>appreciated. I wouldn't mind seeing the average performance,
+> >>(without the spikes) go up -- let's say -- 10%, in exchange for
+> >>more uniform performance. These spikes are a real problem.
+> > 
+> > 
+> > The background writer is designed to address your specific problem.  We
+> > will stil checkpoint, but the spike should be greatly minimized.
+> > 
+> 
+> Thanks. Do you know when 7.5 is expected to be released?
+
+3-6 months.
+
+> Until then, is a workaround known? Also, are the delays I'm seeing out of the ordinary?
+> I'm looking at one case in which two successive transactions, each updating a handful of
+> records, take 26 and 18 *seconds* (not msec) to complete. These transactions normally complete
+> in under 30 msec.
+
+Wow.  Others might know the answer to that.
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 00:24:19 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 10 May 2004 23:23:49 -0400 (EDT)
+To: Jack Orenstein 
+Cc: Jan Wieck , pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints 
+In-reply-to: <40A03435.7020300@geophile.com> 
+References: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+	<40A03435.7020300@geophile.com>
+Comments: In-reply-to Jack Orenstein 
+	message dated "Mon, 10 May 2004 22:02:29 -0400"
+Date: Mon, 10 May 2004 23:23:49 -0400
+Message-ID: <24638.1084245829@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Jack Orenstein  writes:
+> I'm looking at one case in which two successive transactions, each
+> updating a handful of records, take 26 and 18 *seconds* (not msec) to
+> complete. These transactions normally complete in under 30 msec.
+
+I've seen installations in which it seemed that the "normal" query load
+was close to saturating the available disk bandwidth, and the extra load
+imposed by a background VACUUM just pushed the entire system's response
+time over a cliff.  In an installation that has I/O capacity to spare,
+a VACUUM doesn't really hurt foreground query response at all.
+
+I suspect that the same observations hold true for checkpoints, though
+I haven't specifically seen an installation suffering from that effect.
+
+Already-committed changes for 7.5 include a background writer, which
+basically will "trickle" out dirty pages between checkpoints, thereby
+hopefully reducing the volume of I/O forced at a checkpoint.  We have
+also got code in place that throttles the rate of I/O requests during
+VACUUM.  It seems like it might be useful to similarly throttle the I/O
+request rate during a CHECKPOINT, though I'm not sure if there'd be any
+bad side effects from lengthening the elapsed time for a checkpoint.
+(Jan, any thoughts here?)
+
+None of this is necessarily going to fix matters for an installation
+that has no spare I/O capacity, though.  And from the numbers you're
+quoting I fear you may be in that category.  "Buy faster disks" may
+be the only answer ...
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 10:35:46 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-Id: <200405111335.i4BDZLDJ010593@ms-smtp-01.tampabay.rr.com>
+From: "Matthew Nuzum" 
+To: "'Tom Lane'" ,
+	"'Jack Orenstein'" 
+Cc: "'Jan Wieck'" ,
+	
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Tue, 11 May 2004 09:35:18 -0400
+MIME-Version: 1.0
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+	charset="US-ASCII"
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+
+
+> 
+> Jack Orenstein  writes:
+> > I'm looking at one case in which two successive transactions, each
+> > updating a handful of records, take 26 and 18 *seconds* (not msec) to
+> > complete. These transactions normally complete in under 30 msec.
+...
+> None of this is necessarily going to fix matters for an installation
+> that has no spare I/O capacity, though.  And from the numbers you're
+> quoting I fear you may be in that category.  "Buy faster disks" may
+> be the only answer ...
+> 
+
+I had a computer once that had an out-of-the-box hard drive configuration
+that provided horrible disk performance.  I found a tutorial at O'Reilly
+that explained how to use hdparm to dramatically speed up disk performance
+on Linux.  I've noticed on other computers I've set up recently that hdparm
+seems to be used by default out of the box to give good performance.
+
+Maybe your computer is using all of it's I/O capacity because it's using PIO
+mode or some other non-optimal method of accessing the disk.
+
+Just a suggestion, I hope it helps,
+
+Matthew Nuzum		| ISPs: Make $200 - $5,000 per referral by
+www.followers.net		| recomending Elite CMS to your customers!
+matt@followers.net	| http://www.followers.net/isp
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 11:42:07 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 11 May 2004 10:41:49 -0400 (EDT)
+To: Jan Wieck 
+Cc: Jack Orenstein ,
+	pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints 
+In-reply-to: <40A0E069.9000006@Yahoo.com> 
+References: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+	<40A03435.7020300@geophile.com>
+	<24638.1084245829@sss.pgh.pa.us> <40A0E069.9000006@Yahoo.com>
+Comments: In-reply-to Jan Wieck 
+	message dated "Tue, 11 May 2004 10:17:13 -0400"
+Date: Tue, 11 May 2004 10:41:48 -0400
+Message-ID: <9758.1084286508@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Jan Wieck  writes:
+> If we would combine the background writer and the checkpointer,
+
+... which in fact is on my agenda of things to do ...
+
+> then a 
+> "checkpoint flush" could actually be implemented as a temporary change 
+> in that activity that basically is done by not reevaluating the list of 
+> to be flushed blocks any more and switching to a constant amount of 
+> blocks flushed per cycle. When that list get's empty, the checkpoint 
+> flush is done, the checkpoint can complete and the background writer 
+> resumes normal business.
+
+Sounds like a plan.  I'll do it that way.  However, we might want to
+have different configuration settings controlling the write rate during
+checkpoint and the rate during normal background writing --- what do you
+think?
+
+Also, presumably a shutdown checkpoint should just whomp out the data
+without any delays.  We can't afford to wait around and risk having
+init decide we took too long.
+
+>> None of this is necessarily going to fix matters for an installation
+>> that has no spare I/O capacity, though.
+
+> As a matter of fact, the background writer increases the overall IO. It 
+> writes buffers that possibly get modified again before a checkpoint or 
+> their replacement requires them to be finally written. So if there is no 
+> spare IO bandwidth, it makes things worse.
+
+Right, the trickle writes could be wasted effort.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 12:12:55 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A0ED54.7050708@dsvr.net>
+Date: Tue, 11 May 2004 16:12:20 +0100
+From: Rob Fielding 
+User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4.2) Gecko/20040323
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Matthew Nuzum ,
+	pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+References: <200405111335.i4BDZLDJ010593@ms-smtp-01.tampabay.rr.com>
+In-Reply-To: <200405111335.i4BDZLDJ010593@ms-smtp-01.tampabay.rr.com>
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+
+Matthew Nuzum wrote:
+>>Jack Orenstein  writes:
+>>
+>>>I'm looking at one case in which two successive transactions, each
+>>>updating a handful of records, take 26 and 18 *seconds* (not msec) to
+>>>complete. These transactions normally complete in under 30 msec.
+
+>>None of this is necessarily going to fix matters for an installation
+>>that has no spare I/O capacity, though.  And from the numbers you're
+>>quoting I fear you may be in that category.  "Buy faster disks" may
+>>be the only answer ...
+>>
+
+> I had a computer once that had an out-of-the-box hard drive configuration
+> that provided horrible disk performance.  I found a tutorial at O'Reilly
+> that explained how to use hdparm to dramatically speed up disk performance
+> on Linux.  I've noticed on other computers I've set up recently that hdparm
+> seems to be used by default out of the box to give good performance.
+> 
+> Maybe your computer is using all of it's I/O capacity because it's using PIO
+> mode or some other non-optimal method of accessing the disk.
+
+There's certainly some scope there. I have an SGI Octane whos SCSI 2 
+disks were set-up by default with no write buffer and CTQ depth of zero 
+:/ IDE drivers in Linux maybe not detecting your IDE chipset correctly 
+and stepping down, however unlikely there maybe something odd going on 
+but you could check hdparm out. Ensure correct cables too, and the 
+aren't crushed or twisted too bad.... I digress...
+
+Assuming you're running with optimal schema and index design (ie you're 
+not doing extra work unnecessarily), and your backend has 
+better-then-default config options set-up (plenty of tips around here), 
+then disk arrangement is critical to smoothing the ride.
+
+Taking things to a relative extreme, we implemented a set-up with issues 
+similar sounding to yours. It was resolved by first optimising 
+everything but hardware, then finally optimising hardware. This served 
+us because it meant we squeezed as much out of the available hardware, 
+before finally throwing more at it, getting us the best possible returns 
+(plus further post optimisation on the new hardware).
+
+First tip would to take your pg_xlog and put it on another disk (and 
+channel). Next if you're running a journalled fs, get that journal off 
+onto another disk (and channel). Finally, get as many disks for the data 
+store and spread the load across spindles. You're aiming here to 
+distribute the contention and disk I/O more evenly to remove the 
+congestion. sar and iostat help out as part of the analysis.
+
+You say you're using IDE, for which I'd highly recommend switching to 
+SCSI and mutliple controllers because IDE isn't great for lots of other 
+reasons. Obviously budgets count, and playing with SCSI certainly limits 
+that. We took a total of 8 disks across 2 SCSI 160 channels and split up 
+the drives into a number of software RAID arrays. RAID0 mirrors for the 
+os, pg_xlog, data disk journal and swap and the rest became a RAID5 
+array for the data. You could instead implement your DATA disk as 
+RAID1+0 if you wanted more perf at the cost of free space. Anyway, it's 
+certainly not the fastest config out there, but it made all the 
+difference to this particular application. Infact, we had so much free 
+I/O we recently installed another app on there (based on mysql, sorry) 
+which runs concurrently, and itself 4 times faster than it originally did...
+
+YMMV, just my 2p.
+
+-- 
+
+Rob Fielding
+rob@dsvr.net
+
+www.dsvr.co.uk              Development             Designer Servers Ltd
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 13:55:15 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Tue, 11 May 2004 12:52:32 -0400
+From: jao@geophile.com
+To: Rob Fielding 
+Cc: Matthew Nuzum ,
+	pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+References: <200405111335.i4BDZLDJ010593@ms-smtp-01.tampabay.rr.com>
+	<40A0ED54.7050708@dsvr.net>
+In-Reply-To: <40A0ED54.7050708@dsvr.net>
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+
+Quoting Rob Fielding :
+
+> Assuming you're running with optimal schema and index design (ie you're 
+> not doing extra work unnecessarily), and your backend has 
+> better-then-default config options set-up (plenty of tips around here), 
+> then disk arrangement is critical to smoothing the ride.
+
+The schema and queries are extremely simple. I've been experimenting
+with config options. One possibility I'm looking into is whether 
+shared_buffers is too high, at 12000. We have some preliminary evidence
+that setting it lower (1000) reduces the demand for IO bandwidth to
+a point where the spikes become almost tolerable.
+
+> First tip would to take your pg_xlog and put it on another disk (and 
+> channel). 
+
+That's on my list of things to try.
+
+> Next if you're running a journalled fs, get that journal off 
+> onto another disk (and channel). Finally, get as many disks for the data 
+> store and spread the load across spindles. 
+
+Dumb question: how do I spread the data across spindles? Do you have
+a pointer to something I could read?
+
+Jack Orenstein
+
+----------------------------------------------------------------
+This message was sent using IMP, the Internet Messaging Program.
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 14:31:48 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 11 May 2004 11:30:43 -0600 (MDT)
+Date: Tue, 11 May 2004 11:30:31 -0600 (MDT)
+From: "scott.marlowe" 
+To: 
+Cc: Rob Fielding , Matthew Nuzum ,
+	
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <1084294352.40a104d04ad0d@geophile.com>
+Message-ID: 
+MIME-Version: 1.0
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+
+On Tue, 11 May 2004 jao@geophile.com wrote:
+
+> Quoting Rob Fielding :
+> 
+> > Assuming you're running with optimal schema and index design (ie you're 
+> > not doing extra work unnecessarily), and your backend has 
+> > better-then-default config options set-up (plenty of tips around here), 
+> > then disk arrangement is critical to smoothing the ride.
+> 
+> The schema and queries are extremely simple. I've been experimenting
+> with config options. One possibility I'm looking into is whether 
+> shared_buffers is too high, at 12000. We have some preliminary evidence
+> that setting it lower (1000) reduces the demand for IO bandwidth to
+> a point where the spikes become almost tolerable.
+
+If the shared_buffers are large, postgresql seems to have a performance 
+issue with handling them.  Plus they can cause the kernel to dump cache on 
+things that would otherwise be right there and therefore forces the 
+database to hit the drives.  You might wanna try settings between 1000 and 
+10000 and see where your sweet spot is.
+
+> > First tip would to take your pg_xlog and put it on another disk (and 
+> > channel). 
+> 
+> That's on my list of things to try.
+> 
+> > Next if you're running a journalled fs, get that journal off 
+> > onto another disk (and channel). Finally, get as many disks for the data 
+> > store and spread the load across spindles. 
+> 
+> Dumb question: how do I spread the data across spindles? Do you have
+> a pointer to something I could read?
+
+Look into a high quality hardware RAID controller with battery backed 
+cache on board.  We use the ami/lsi megaraid and I'm quite pleased with 
+its writing performance.
+
+How you configure your drives is up to you.  For smaller numbers of 
+drives (6 or less) RAID 1+0 is usually a clear winner.  For medium numbers 
+of drives, say 8 to 20, RAID 5 works well.  For more drives than that, 
+many folks report RAID 5+0 or 0+5 to work well.
+
+I've only played around with 12 or fewer drives, so I'm saying RAID 5+0 is 
+a good choice from my experience, just reflecting back what I've heard 
+here on the performance mailing list.
+
+If you're not doing much writing, then a software RAID may be a good 
+intermediate solution, especially RAID1 with >2 disks under linux seems a 
+good setup for a mostly read database.
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 16:13:26 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Tue, 11 May 2004 21:06:58 +0200
+From: Bjoern Metzdorf 
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+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Cc: "Pgsql-Admin (E-mail)" 
+Subject: Quad processor options
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Sequence-Number: 13400
+
+Hi,
+
+I am curious if there are any real life production quad processor setups 
+running postgresql out there. Since postgresql lacks a proper 
+replication/cluster solution, we have to buy a bigger machine.
+
+Right now we are running on a dual 2.4 Xeon, 3 GB Ram and U160 SCSI 
+hardware-raid 10.
+
+Has anyone experiences with quad Xeon or quad Opteron setups? I am 
+looking at the appropriate boards from Tyan, which would be the only 
+option for us to buy such a beast. The 30k+ setups from Dell etc. don't 
+fit our budget.
+
+I am thinking of the following:
+
+Quad processor (xeon or opteron)
+5 x SCSI 15K RPM for Raid 10 + spare drive
+2 x IDE for system
+ICP-Vortex battery backed U320 Hardware Raid
+4-8 GB Ram
+
+Would be nice to hear from you.
+
+Regards,
+Bjoern
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 16:13:05 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+References: <200405111335.i4BDZLDJ010593@ms-smtp-01.tampabay.rr.com>
+	<40A0ED54.7050708@dsvr.net> <1084294352.40a104d04ad0d@geophile.com>
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+Cc: Matthew Nuzum ,
+	pgsql-performance@postgresql.org, Rob Fielding 
+From: Paul Tuckfield 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Tue, 11 May 2004 12:12:35 -0700
+To: jao@geophile.com
+X-Mailer: Apple Mail (2.613)
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+
+The king of statistics in these cases, is probably vmstat.  one can 
+drill down on specific things from there, but first you should send 
+some vmstat output.
+
+Reducing cache -> reducing IO suggests to me the OS might be paging out 
+shared buffers.   This is indicated by activity in the "si" and "so" 
+columns of vmstat.   intentional disk activity by the 
+applciation(postgres) shows up in the 	"bi" and "bo" columns.
+
+If you are having a "write storm" or bursty writes that's burying 
+performance, a scsi raid controler with writeback cache will greatly 
+improve the situation, but I do believe they run around $1-2k.   If 
+it's write specific problem, the cache matters more than the striping, 
+except to say that write specfic perf problems should avoid raid5
+
+please send the output of "vmstat 10" for about 10 minutes, spanning 
+good performance and bad performance.
+
+
+
+
+
+On May 11, 2004, at 9:52 AM, jao@geophile.com wrote:
+
+> Quoting Rob Fielding :
+>
+>> Assuming you're running with optimal schema and index design (ie 
+>> you're
+>> not doing extra work unnecessarily), and your backend has
+>> better-then-default config options set-up (plenty of tips around 
+>> here),
+>> then disk arrangement is critical to smoothing the ride.
+>
+> The schema and queries are extremely simple. I've been experimenting
+> with config options. One possibility I'm looking into is whether
+> shared_buffers is too high, at 12000. We have some preliminary evidence
+> that setting it lower (1000) reduces the demand for IO bandwidth to
+> a point where the spikes become almost tolerable.
+>
+>> First tip would to take your pg_xlog and put it on another disk (and
+>> channel).
+>
+> That's on my list of things to try.
+>
+>> Next if you're running a journalled fs, get that journal off
+>> onto another disk (and channel). Finally, get as many disks for the 
+>> data
+>> store and spread the load across spindles.
+>
+> Dumb question: how do I spread the data across spindles? Do you have
+> a pointer to something I could read?
+>
+> Jack Orenstein
+>
+> ----------------------------------------------------------------
+> This message was sent using IMP, the Internet Messaging Program.
+>
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+>       message can get through to the mailing list cleanly
+>
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 16:33:25 2004
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+Subject: Re: [PERFORM] Quad processor options
+Date: Tue, 11 May 2004 15:32:57 -0400
+Message-ID: 
+ <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098228@vt-pe2550-001.vantage.vantage.com>
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+Thread-Topic: [PERFORM] Quad processor options
+Thread-Index: AcQ3jCCYdiFvPLlYQcmfiU3ipTdeGwAAd/0E
+From: "Anjan Dave" 
+To: "Bjoern Metzdorf" ,
+	
+Cc: "Pgsql-Admin (E-mail)" 
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+From pgsql-admin-owner@postgresql.org  Tue May 11 17:15:29 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+References: <40A12452.3040505@turtle-entertainment.de>
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+Cc: "Pgsql-Admin (E-mail)" ,
+	pgsql-performance@postgresql.org
+From: Paul Tuckfield 
+Subject: Re: [PERFORM] Quad processor options
+Date: Tue, 11 May 2004 13:14:59 -0700
+To: Bjoern Metzdorf 
+X-Mailer: Apple Mail (2.613)
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+
+it's very good to understand specific choke points you're trying to 
+address by upgrading so you dont get disappointed.  Are you truly CPU 
+constrained, or is it memory footprint or IO thruput that makes you 
+want to upgrade?
+
+IMO The best way to begin understanding system choke points is vmstat 
+output.
+
+Would you mind forwarding the output of "vmstat 10 120" under peak load 
+period?  (I'm asusming this is linux or unix variant)  a brief 
+description of what is happening during the vmstat sample would help a 
+lot too.
+
+
+
+> I am curious if there are any real life production quad processor 
+> setups running postgresql out there. Since postgresql lacks a proper 
+> replication/cluster solution, we have to buy a bigger machine.
+>
+> Right now we are running on a dual 2.4 Xeon, 3 GB Ram and U160 SCSI 
+> hardware-raid 10.
+>
+> Has anyone experiences with quad Xeon or quad Opteron setups? I am 
+> looking at the appropriate boards from Tyan, which would be the only 
+> option for us to buy such a beast. The 30k+ setups from Dell etc. 
+> don't fit our budget.
+>
+> I am thinking of the following:
+>
+> Quad processor (xeon or opteron)
+> 5 x SCSI 15K RPM for Raid 10 + spare drive
+> 2 x IDE for system
+> ICP-Vortex battery backed U320 Hardware Raid
+> 4-8 GB Ram
+>
+> Would be nice to hear from you.
+>
+> Regards,
+> Bjoern
+>
+> ---------------------------(end of 
+> broadcast)---------------------------
+> TIP 4: Don't 'kill -9' the postmaster
+>
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 17:17:43 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+	Tue, 11 May 2004 14:16:48 -0600 (MDT)
+Date: Tue, 11 May 2004 14:16:36 -0600 (MDT)
+From: "scott.marlowe" 
+To: Bjoern Metzdorf 
+Cc: ,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+In-Reply-To: <40A12452.3040505@turtle-entertainment.de>
+Message-ID: 
+MIME-Version: 1.0
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+
+On Tue, 11 May 2004, Bjoern Metzdorf wrote:
+
+> Hi,
+> 
+> I am curious if there are any real life production quad processor setups 
+> running postgresql out there. Since postgresql lacks a proper 
+> replication/cluster solution, we have to buy a bigger machine.
+> 
+> Right now we are running on a dual 2.4 Xeon, 3 GB Ram and U160 SCSI 
+> hardware-raid 10.
+> 
+> Has anyone experiences with quad Xeon or quad Opteron setups? I am 
+> looking at the appropriate boards from Tyan, which would be the only 
+> option for us to buy such a beast. The 30k+ setups from Dell etc. don't 
+> fit our budget.
+> 
+> I am thinking of the following:
+> 
+> Quad processor (xeon or opteron)
+> 5 x SCSI 15K RPM for Raid 10 + spare drive
+> 2 x IDE for system
+> ICP-Vortex battery backed U320 Hardware Raid
+> 4-8 GB Ram
+
+Well, from what I've read elsewhere on the internet, it would seem the 
+Opterons scale better to 4 CPUs than the basic Xeons do.  Of course, the 
+exception to this is SGI's altix, which uses their own chipset and runs 
+the itanium with very good memory bandwidth.
+
+But, do you really need more CPU horsepower?
+
+Are you I/O or CPU or memory or memory bandwidth bound?  If you're sitting 
+at 99% idle, and iostat says your drives are only running at some small 
+percentage of what you know they could, you might be memory or memory 
+bandwidth limited.  Adding two more CPUs will not help with that 
+situation.
+
+If your I/O is saturated, then the answer may well be a better RAID 
+array, with many more drives plugged into it.  Do you have any spare 
+drives you can toss on the machine to see if that helps?  Sometimes going 
+from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big boost in 
+performance.
+
+In short, don't expect 4 CPUs to solve the problem if the problem isn't 
+really the CPUs being maxed out.
+
+Also, what type of load are you running?  Mostly read, mostly written, few 
+connections handling lots of data, lots of connections each handling a 
+little data, lots of transactions, etc...
+
+If you are doing lots of writing, make SURE you have a controller that 
+supports battery backed cache and is configured to write-back, not 
+write-through.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 17:23:46 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 11 May 2004 14:22:52 -0600 (MDT)
+Date: Tue, 11 May 2004 14:22:40 -0600 (MDT)
+From: "scott.marlowe" 
+To: Paul Tuckfield 
+Cc: , Matthew Nuzum ,
+	, Rob Fielding 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <29010F48-A37F-11D8-A34F-000393BD6C3E@tuckfield.com>
+Message-ID: 
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+
+On Tue, 11 May 2004, Paul Tuckfield wrote:
+
+> If you are having a "write storm" or bursty writes that's burying 
+> performance, a scsi raid controler with writeback cache will greatly 
+> improve the situation, but I do believe they run around $1-2k.   If 
+> it's write specific problem, the cache matters more than the striping, 
+> except to say that write specfic perf problems should avoid raid5
+
+Actually, a single channel MegaRAID 320-1 (single channel ultra 320) is 
+only $421 at http://www.siliconmechanics.com/c248/u320-scsi.php  It works 
+pretty well for me, having 6 months of a production server on one with 
+zero hickups and very good performance.  They have a dual channel intel 
+card for only $503, but I'm not at all familiar with that card.
+
+The top of the line megaraid is the 320-4, which is only $1240, which 
+ain't bad for a four channel RAID controller.
+
+Battery backed cache is an addon, but I think it's only about $80 or so.
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 17:29:05 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Tue, 11 May 2004 22:28:12 +0200
+From: Bjoern Metzdorf 
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+To: Anjan Dave 
+Cc: pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+References: 
+ <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098228@vt-pe2550-001.vantage.vantage.com>
+In-Reply-To: 
+ <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098228@vt-pe2550-001.vantage.vantage.com>
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+Anjan Dave wrote:
+
+> We use XEON Quads (PowerEdge 6650s) and they work nice,
+ > provided you configure the postgres properly.
+ > Dell is the cheapest quad you can buy i think.
+ > You shouldn't be paying 30K unless you are getting high CPU-cache
+ > on each processor and tons of memory.
+
+good to hear, I tried to online configure a quad xeon here at dell 
+germany, but the 6550 is not available for online configuration. at dell 
+usa it works. I will give them a call tomorrow.
+
+> I am actually curious, have you researched/attempted any 
+ > postgresql clustering solutions?
+ > I agree, you can't just keep buying bigger machines.
+
+There are many asynchronous, trigger based solutions out there (eRserver 
+etc..), but what we need is basically a master <-> master setup, which 
+seems not to be available soon for postgresql.
+
+Our current dual Xeon runs at 60-70% average cpu load, which is really 
+much. I cannot afford any trigger overhead here. This machine is 
+responsible for over 30M page impressions per month, 50 page impressums 
+per second at peak times. The autovacuum daemon is a god sent gift :)
+
+I'm curious how the recently announced mysql cluster will perform, 
+although it is not an option for us. postgresql has far superior 
+functionality.
+
+> They have 5 internal drives (4 in RAID 10, 1 spare) on U320, 
+ > 128MB cache on the PERC controller, 8GB RAM.
+
+Could you tell me what you paid approximately for this setup?
+
+How does it perform? It certainly won't be twice as fast a as dual xeon, 
+but I remember benchmarking a quad P3 xeon some time ago, and it was 
+disappointingly slow...
+
+Regards,
+Bjoern
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 17:44:35 2004
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+Subject: Re: [PERFORM] Quad processor options
+Date: Tue, 11 May 2004 16:38:28 -0400
+Message-ID: 
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+Thread-Topic: [PERFORM] Quad processor options
+Thread-Index: AcQ3lny4KvjCBVzMQ+ip0WR3uVO4sQAAIA0X
+From: "Anjan Dave" 
+To: "Bjoern Metzdorf" 
+Cc: ,
+	"Pgsql-Admin (E-mail)" 
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+
+From pgsql-admin-owner@postgresql.org  Tue May 11 17:42:48 2004
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+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A13A78.9000607@turtle-entertainment.de>
+Date: Tue, 11 May 2004 22:41:28 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: "scott.marlowe" 
+Cc: pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+References: 
+In-Reply-To: 
+Content-Type: multipart/mixed; boundary="------------000602000605060104090100"
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+This is a multi-part message in MIME format.
+--------------000602000605060104090100
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+
+scott.marlowe wrote:
+
+> Well, from what I've read elsewhere on the internet, it would seem the 
+> Opterons scale better to 4 CPUs than the basic Xeons do.  Of course, the 
+> exception to this is SGI's altix, which uses their own chipset and runs 
+> the itanium with very good memory bandwidth.
+
+This is basically what I read too. But I cannot spent money on a quad 
+opteron just for testing purposes :)
+
+> But, do you really need more CPU horsepower?
+> 
+> Are you I/O or CPU or memory or memory bandwidth bound?  If you're sitting 
+> at 99% idle, and iostat says your drives are only running at some small 
+> percentage of what you know they could, you might be memory or memory 
+> bandwidth limited.  Adding two more CPUs will not help with that 
+> situation.
+
+Right now we have a dual xeon 2.4, 3 GB Ram, Mylex extremeraid 
+controller, running 2 Compaq BD018122C0, 1 Seagate ST318203LC and 1 
+Quantum ATLAS_V_18_SCA.
+
+iostat show between 20 and 60 % user avg-cpu. And this is not even peak 
+time.
+
+I attached a "vmstat 10 120" output for perhaps 60-70% peak load.
+
+> If your I/O is saturated, then the answer may well be a better RAID 
+> array, with many more drives plugged into it.  Do you have any spare 
+> drives you can toss on the machine to see if that helps?  Sometimes going 
+> from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big boost in 
+> performance.
+
+Next drives I'll buy will certainly be 15k scsi drives.
+
+> In short, don't expect 4 CPUs to solve the problem if the problem isn't 
+> really the CPUs being maxed out.
+> 
+> Also, what type of load are you running?  Mostly read, mostly written, few 
+> connections handling lots of data, lots of connections each handling a 
+> little data, lots of transactions, etc...
+
+In peak times we can get up to 700-800 connections at the same time. 
+There are quite some updates involved, without having exact numbers I'll 
+think that we have about 70% selects and 30% updates/inserts.
+
+> If you are doing lots of writing, make SURE you have a controller that 
+> supports battery backed cache and is configured to write-back, not 
+> write-through.
+
+Could you recommend a certain controller type? The only battery backed 
+one that I found on the net is the newest model from icp-vortex.com.
+
+Regards,
+Bjoern
+
+--------------000602000605060104090100
+Content-Type: text/plain;
+ name="vmstat.txt"
+Content-Transfer-Encoding: 7bit
+Content-Disposition: inline;
+ filename="vmstat.txt"
+
+~# vmstat 10 120
+   procs                      memory    swap          io     system         cpu
+ r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
+ 1  1  0  24180  10584  32468 2332208   0   1     0     2    1     2   2   0   0
+ 0  2  0  24564  10480  27812 2313528   8   0  7506   574 1199  8674  30   7  63
+ 2  1  0  24692  10060  23636 2259176   0  18  8099   298 2074  6328  25   7  68
+ 2  0  0  24584  18576  21056 2299804   3   6 13208   305 1598  8700  23   6  71
+ 1 21  1  24504  16588  20912 2309468   4   0  1442  1107  754  6874  42  13  45
+ 6  1  0  24632  13148  19992 2319400   0   0  2627   499 1184  9633  37   6  58
+ 5  1  0  24488  10912  19292 2330080   5   0  3404   150 1466 10206  32   6  61
+ 4  1  0  24488  12180  18824 2342280   3   0  2934    40 1052  3866  19   3  78
+ 0  0  0  24420  14776  19412 2347232   6   0   403   216 1123  4702  22   3  74
+ 0  0  0  24548  14408  17380 2321780   4   0   522   715  965  6336  25   5  71
+ 4  0  0  24676  12504  17756 2322988   0   0   564   830  883  7066  31   6  63
+ 0  3  0  24676  14060  18232 2325224   0   0   483   388 1097  3401  21   3  76
+ 0  2  1  24676  13044  18700 2322948   0   0   701   195 1078  5187  23   3  74
+ 2  0  0  24676  21576  18752 2328168   0   0   467   177 1552  3574  18   3  78
+
+--------------000602000605060104090100--
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 18:11:09 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Tue, 11 May 2004 22:45:13 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Anjan Dave 
+Cc: pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+References: 
+ <4BAFBB6B9CC46F41B2AD7D9F4BBAF78509822A@vt-pe2550-001.vantage.vantage.com>
+In-Reply-To: 
+ <4BAFBB6B9CC46F41B2AD7D9F4BBAF78509822A@vt-pe2550-001.vantage.vantage.com>
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+
+Anjan Dave wrote:
+
+> Did you mean to say the trigger-based clustering solution 
+ > is loading the dual CPUs 60-70% right now?
+
+No, this is without any triggers involved.
+
+> Performance will not be linear with more processors, 
+ > but it does help with more processes.
+ > We haven't benchmarked it, but we haven't had any
+ > problems also so far in terms of performance.
+
+ From the amount of processes view, we certainly can saturate a quad 
+setup :)
+
+> Price would vary with your relation/yearly purchase, etc, 
+ > but a 6650 with 2.0GHz/1MB cache/8GB Memory, RAID card,
+ > drives, etc, should definitely cost you less than 20K USD.
+
+Which is still very much. Anyone have experience with a self built quad 
+xeon, using the Tyan Thunder board?
+
+Regards,
+Bjoern
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 17:53:45 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+Message-ID: <40A13BAB.5080500@turtle-entertainment.de>
+Date: Tue, 11 May 2004 22:46:35 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Paul Tuckfield 
+Cc: "Pgsql-Admin (E-mail)" ,
+	pgsql-performance@postgresql.org
+Subject: Re: [PERFORM] Quad processor options
+References: <40A12452.3040505@turtle-entertainment.de>
+	
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+Paul Tuckfield wrote:
+
+> Would you mind forwarding the output of "vmstat 10 120" under peak load 
+> period?  (I'm asusming this is linux or unix variant)  a brief 
+> description of what is happening during the vmstat sample would help a 
+> lot too.
+
+see my other mail.
+
+We are running Linux, Kernel 2.4. As soon as the next debian version 
+comes out, I'll happily switch to 2.6 :)
+
+Regards,
+Bjoern
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 18:10:41 2004
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+	Tue, 11 May 2004 15:02:36 -0600 (MDT)
+Date: Tue, 11 May 2004 15:02:24 -0600 (MDT)
+From: "scott.marlowe" 
+To: Bjoern Metzdorf 
+Cc: ,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+In-Reply-To: <40A13A78.9000607@turtle-entertainment.de>
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+
+On Tue, 11 May 2004, Bjoern Metzdorf wrote:
+
+> scott.marlowe wrote:
+> 
+> > Well, from what I've read elsewhere on the internet, it would seem the 
+> > Opterons scale better to 4 CPUs than the basic Xeons do.  Of course, the 
+> > exception to this is SGI's altix, which uses their own chipset and runs 
+> > the itanium with very good memory bandwidth.
+> 
+> This is basically what I read too. But I cannot spent money on a quad 
+> opteron just for testing purposes :)
+
+Wouldn't it be nice to just have a lab full of these things?
+
+> > If your I/O is saturated, then the answer may well be a better RAID 
+> > array, with many more drives plugged into it.  Do you have any spare 
+> > drives you can toss on the machine to see if that helps?  Sometimes going 
+> > from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big boost in 
+> > performance.
+> 
+> Next drives I'll buy will certainly be 15k scsi drives.
+
+Better to buy more 10k drives than fewer 15k drives.  Other than slightly 
+faster select times, the 15ks aren't really any faster.
+
+> > In short, don't expect 4 CPUs to solve the problem if the problem isn't 
+> > really the CPUs being maxed out.
+> > 
+> > Also, what type of load are you running?  Mostly read, mostly written, few 
+> > connections handling lots of data, lots of connections each handling a 
+> > little data, lots of transactions, etc...
+> 
+> In peak times we can get up to 700-800 connections at the same time. 
+> There are quite some updates involved, without having exact numbers I'll 
+> think that we have about 70% selects and 30% updates/inserts.
+
+Wow, a lot of writes then.
+
+> > If you are doing lots of writing, make SURE you have a controller that 
+> > supports battery backed cache and is configured to write-back, not 
+> > write-through.
+> 
+> Could you recommend a certain controller type? The only battery backed 
+> one that I found on the net is the newest model from icp-vortex.com.
+
+Sure, adaptec makes one, so does lsi megaraid.  Dell resells both of 
+these, the PERC3DI and the PERC3DC are adaptec, then lsi in that order, I 
+believe.  We run the lsi megaraid with 64 megs battery backed cache.
+
+Intel also makes one, but I've heard nothing about it.
+
+If you get the LSI megaraid, make sure you're running the latest megaraid 
+2 driver, not the older, slower 1.18 series.  If you are running linux, 
+look for the dkms packaged version.  dkms, (Dynamic Kernel Module System) 
+automagically compiles and installs source rpms for drivers when you 
+install them, and configures the machine to use them to boot up.  Most 
+drivers seem to be slowly headed that way in the linux universe, and I 
+really like the simplicity and power of dkms.
+
+I haven't directly tested anything but the adaptec and the lsi megaraid.  
+Here at work we've had massive issues trying to get the adaptec cards 
+configured and installed on, while the megaraid was a snap.  Installed RH, 
+installed the dkms rpm, installed the dkms enabled megaraid driver and 
+rebooted.  Literally, that's all it took.
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 18:15:49 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+Message-ID: <40A14170.7000201@turtle-entertainment.de>
+Date: Tue, 11 May 2004 23:11:12 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: "scott.marlowe" 
+Cc: pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+References: 
+In-Reply-To: 
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+
+scott.marlowe wrote:
+>>Next drives I'll buy will certainly be 15k scsi drives.
+> 
+> Better to buy more 10k drives than fewer 15k drives.  Other than slightly 
+> faster select times, the 15ks aren't really any faster.
+
+Good to know. I'll remember that.
+
+>>In peak times we can get up to 700-800 connections at the same time. 
+>>There are quite some updates involved, without having exact numbers I'll 
+>>think that we have about 70% selects and 30% updates/inserts.
+> 
+> Wow, a lot of writes then.
+
+Yes, it certainly could also be only 15-20% updates/inserts, but this is 
+also not negligible.
+
+> Sure, adaptec makes one, so does lsi megaraid.  Dell resells both of 
+> these, the PERC3DI and the PERC3DC are adaptec, then lsi in that order, I 
+> believe.  We run the lsi megaraid with 64 megs battery backed cache.
+
+The LSI sounds good.
+
+> Intel also makes one, but I've heard nothing about it.
+
+It could well be the ICP Vortex one, ICP was bought by Intel some time ago..
+
+> I haven't directly tested anything but the adaptec and the lsi megaraid.  
+> Here at work we've had massive issues trying to get the adaptec cards 
+> configured and installed on, while the megaraid was a snap.  Installed RH, 
+> installed the dkms rpm, installed the dkms enabled megaraid driver and 
+> rebooted.  Literally, that's all it took.
+
+I didn't hear anything about dkms for debian, so I will be hand-patching 
+as usual :)
+
+Regards,
+Bjoern
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 18:30:34 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+Date: Tue, 11 May 2004 15:29:46 -0600 (MDT)
+From: "scott.marlowe" 
+To: Bjoern Metzdorf 
+Cc: ,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+In-Reply-To: <40A14170.7000201@turtle-entertainment.de>
+Message-ID: 
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+
+On Tue, 11 May 2004, Bjoern Metzdorf wrote:
+
+> scott.marlowe wrote:
+> > Sure, adaptec makes one, so does lsi megaraid.  Dell resells both of 
+> > these, the PERC3DI and the PERC3DC are adaptec, then lsi in that order, I 
+> > believe.  We run the lsi megaraid with 64 megs battery backed cache.
+> 
+> The LSI sounds good.
+> 
+> > Intel also makes one, but I've heard nothing about it.
+> 
+> It could well be the ICP Vortex one, ICP was bought by Intel some time ago..
+
+Also, there are bigger, faster external RAID boxes as well, that make the 
+internal cards seem puny.  They're nice because all you need in your main 
+box is a good U320 controller to plug into the external RAID array.
+
+That URL I mentioned earlier that had prices has some of the external 
+boxes listed.  No price, not for sale on the web, get out the checkbook 
+and write a blank check is my guess.  I.e. they're not cheap.
+
+The other nice thing about the LSI cards is that you can install >1 and 
+the act like one big RAID array.  i.e. install two cards with a 20 drive 
+RAID0 then make a RAID1 across them, and if one or the other cards itself 
+fails, you've still got 100% of your data sitting there.  Nice to know you 
+can survive the complete failure of one half of your chain.
+
+> > I haven't directly tested anything but the adaptec and the lsi megaraid.  
+> > Here at work we've had massive issues trying to get the adaptec cards 
+> > configured and installed on, while the megaraid was a snap.  Installed RH, 
+> > installed the dkms rpm, installed the dkms enabled megaraid driver and 
+> > rebooted.  Literally, that's all it took.
+> 
+> I didn't hear anything about dkms for debian, so I will be hand-patching 
+> as usual :)
+
+Yeah, it seems to be an RPM kinda thing.  But, I'm thinking the 2.0 
+drivers got included in the latest 2.6 kernels, so no biggie. I was 
+looking around in google, and it definitely appears the 2.x and 1.x 
+megaraid drivers were merged into "unified" driver in 2.6 kernel.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:02:12 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Tue, 11 May 2004 17:36:31 -0400
+To: psql-performance@postgresql.org
+From: Doug Y 
+Subject: Clarification on some settings
+Mime-Version: 1.0
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+
+Hello,
+   I've been having some performance issues with a DB I use. I'm trying to 
+come up with some performance recommendations to send to the "adminstrator".
+
+Hardware:
+CPU0: Pentium III (Coppermine) 1000MHz (256k cache)
+CPU1: Pentium III (Coppermine) 1000MHz (256k cache)
+Memory: 3863468 kB (4 GB)
+OS: Red Hat Linux release 7.2 (Enigma)
+Kernel: 2.4.9-31smp
+I/O I believe is a 3-disk raid 5.
+
+/proc/sys/kernel/shmmax and /proc/sys/kernel/shmall were set to 2G
+
+Postgres version: 7.3.4
+
+I know its a bit dated, and upgrades are planned, but several months out. 
+Load average seems to hover between 1.0 and 5.0-ish during peak hours. CPU 
+seems to be the limiting factor but I'm not positive (cpu utilization seems 
+to be 40-50%). We have 2 of those set up as the back end to 3 web-servers 
+each... supposedly load-balanced, but one of the 2 dbs consistently has 
+higher load. We have a home-grown replication system that keeps them in 
+sync with each other... peer to peer (master/master).
+
+The DB schema is, well to put it nicely... not exactly normalized. No 
+constraints to speak of except for the requisite not-nulls on the primary 
+keys (many of which are compound). Keys are mostly varchar(256) fields.
+
+Ok for what I'm uncertain of...
+shared_buffers:
+According to http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+Its more of a staging area and more isn't necessarily better. That psql 
+relies on the OS to cache data for later use.
+But according to 
+http://www.ca.postgresql.org/docs/momjian/hw_performance/node3.html its 
+where psql caches previous data for queries because the OS cache is slower, 
+and should be as big as possible without causing swap.
+Those seem to be conflicting statements. In our case, the "administrator" 
+kept increasing this until performance seemed to increase, which means its 
+now 250000 (x 8k is 2G).
+Is this just a staging area for data waiting to move to the OS cache, or is 
+this really the area that psql caches its data?
+
+effective_cache_size:
+Again, according to the Varlena guide this tells psql how much system 
+memory is available for it to do its work in.
+until recently, this was set at the default value of 1000. It was just 
+recently increased to 180000 (1.5G)
+according to 
+http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html it 
+should be about 25% of memory?
+
+Finally sort_mem:
+Was until recently left at the default of 1000. Is now 16000.
+
+Increasing the effective cache and sort mem didn't seem to make much of a 
+difference. I'm guessing the eff cache was probably raised a bit too much, 
+and shared_buffers is way to high.
+
+What can I do to help determine what the proper settings should be and/or 
+look at other possible choke points. What should I look for in iostat, 
+mpstat, or vmstat as red flags that cpu, memory, or i/o bound?
+
+DB maintenance wise, I don't believe they were running vacuum full until I 
+told them a few months ago that regular vacuum analyze no longer cleans out 
+dead tuples. Now normal vac is run daily, vac full weekly (supposedly). How 
+can I tell from the output of vacuum if the vac fulls aren't being done, or 
+not done often enough? Or from the system tables, what can I read?
+
+Is there anywhere else I can look for possible clues? I have access to the 
+DB super-user, but not the system root/user.
+
+Thank you for your time. Please let me know any help or suggestions you may 
+have. Unfortunately upgrading postgres, OS, kernel, or re-writing schema is 
+most likely not an option.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 18:43:17 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+From: "Rob Sell" 
+To: 
+Subject: Re: Quad processor options
+Date: Tue, 11 May 2004 16:42:57 -0500
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+
+-----Original Message-----
+From: pgsql-performance-owner@postgresql.org
+[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Bjoern Metzdorf
+Sent: Tuesday, May 11, 2004 3:11 PM
+To: scott.marlowe
+Cc: pgsql-performance@postgresql.org; Pgsql-Admin (E-mail)
+Subject: Re: [PERFORM] Quad processor options
+
+scott.marlowe wrote:
+>>Next drives I'll buy will certainly be 15k scsi drives.
+> 
+> Better to buy more 10k drives than fewer 15k drives.  Other than slightly 
+> faster select times, the 15ks aren't really any faster.
+
+Good to know. I'll remember that.
+
+>>In peak times we can get up to 700-800 connections at the same time. 
+>>There are quite some updates involved, without having exact numbers I'll 
+>>think that we have about 70% selects and 30% updates/inserts.
+> 
+> Wow, a lot of writes then.
+
+Yes, it certainly could also be only 15-20% updates/inserts, but this is 
+also not negligible.
+
+> Sure, adaptec makes one, so does lsi megaraid.  Dell resells both of 
+> these, the PERC3DI and the PERC3DC are adaptec, then lsi in that order, I 
+> believe.  We run the lsi megaraid with 64 megs battery backed cache.
+
+The LSI sounds good.
+
+> Intel also makes one, but I've heard nothing about it.
+
+It could well be the ICP Vortex one, ICP was bought by Intel some time ago..
+
+> I haven't directly tested anything but the adaptec and the lsi megaraid.  
+> Here at work we've had massive issues trying to get the adaptec cards 
+> configured and installed on, while the megaraid was a snap.  Installed RH,
+
+> installed the dkms rpm, installed the dkms enabled megaraid driver and 
+> rebooted.  Literally, that's all it took.
+
+I didn't hear anything about dkms for debian, so I will be hand-patching 
+as usual :)
+
+Regards,
+Bjoern
+
+
+-------------------------
+
+Personally I would stay away from anything intel over 2 processors.  I have
+done some research and if memory serves it something like this. Intel's
+architecture makes each processor compete for bandwidth on the bus to the
+ram. Amd differs in that each proc has its own bus to the ram.
+
+Don't take this as god's honest fact but just keep it in mind when
+considering a Xeon solution, it may be worth your time to do some deeper
+research into this. There is some on this here
+http://www4.tomshardware.com/cpu/20030422/ 
+
+Rob
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 18:47:10 2004
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+	Tue, 11 May 2004 16:47:12 -0500 (CDT)
+From: "Rob Sell" 
+To: 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Tue, 11 May 2004 16:47:05 -0500
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+
+
+-----Original Message-----
+From: pgsql-performance-owner@postgresql.org
+[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of scott.marlowe
+Sent: Tuesday, May 11, 2004 2:23 PM
+To: Paul Tuckfield
+Cc: jao@geophile.com; Matthew Nuzum; pgsql-performance@postgresql.org; Rob
+Fielding
+Subject: Re: [PERFORM] Configuring PostgreSQL to minimize impact of
+checkpoints
+
+On Tue, 11 May 2004, Paul Tuckfield wrote:
+
+> If you are having a "write storm" or bursty writes that's burying 
+> performance, a scsi raid controler with writeback cache will greatly 
+> improve the situation, but I do believe they run around $1-2k.   If 
+> it's write specific problem, the cache matters more than the striping, 
+> except to say that write specfic perf problems should avoid raid5
+
+Actually, a single channel MegaRAID 320-1 (single channel ultra 320) is 
+only $421 at http://www.siliconmechanics.com/c248/u320-scsi.php  It works 
+pretty well for me, having 6 months of a production server on one with 
+zero hickups and very good performance.  They have a dual channel intel 
+card for only $503, but I'm not at all familiar with that card.
+
+The top of the line megaraid is the 320-4, which is only $1240, which 
+ain't bad for a four channel RAID controller.
+
+Battery backed cache is an addon, but I think it's only about $80 or so.
+
+
+---------------------------(end of broadcast)---------------------------
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+
+-----------------------------
+
+If you don't mind slumming on ebay :-) keep an eye out for PERC III cards,
+they are dell branded LSI cards. Perc = Power Edge Raid Controller. There
+are models on there dual channel u320 and dell usually sells them with
+battery backed cache.  That's how I have acquired all my high end raid
+cards.
+
+Rob
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 18:53:14 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Cc: , Matthew Nuzum ,
+	, Rob Fielding 
+From: Paul Tuckfield 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Tue, 11 May 2004 14:52:57 -0700
+To: "scott.marlowe" 
+X-Mailer: Apple Mail (2.613)
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+
+Love that froogle.
+
+It looks like a nice card.     One thing I didn't get straight is if 
+the cache is writethru or write back.
+
+If the original posters problem is truly a burst write problem (and not 
+linux caching or virtual memory overcommitment) then writeback is key.
+
+
+
+
+> On Tue, 11 May 2004, Paul Tuckfield wrote:
+>
+>> If you are having a "write storm" or bursty writes that's burying
+>> performance, a scsi raid controler with writeback cache will greatly
+>> improve the situation, but I do believe they run around $1-2k.   If
+>> it's write specific problem, the cache matters more than the striping,
+>> except to say that write specfic perf problems should avoid raid5
+>
+> Actually, a single channel MegaRAID 320-1 (single channel ultra 320) is
+> only $421 at http://www.siliconmechanics.com/c248/u320-scsi.php  It 
+> works
+> pretty well for me, having 6 months of a production server on one with
+> zero hickups and very good performance.  They have a dual channel intel
+> card for only $503, but I'm not at all familiar with that card.
+>
+> The top of the line megaraid is the 320-4, which is only $1240, which
+> ain't bad for a four channel RAID controller.
+>
+> Battery backed cache is an addon, but I think it's only about $80 or 
+> so.
+>
+>
+> ---------------------------(end of 
+> broadcast)---------------------------
+> TIP 3: if posting/reading through Usenet, please send an appropriate
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+>       message can get through to the mailing list cleanly
+>
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:08:34 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Tue, 11 May 2004 16:07:48 -0600 (MDT)
+Date: Tue, 11 May 2004 16:07:36 -0600 (MDT)
+From: "scott.marlowe" 
+To: Paul Tuckfield 
+Cc: , Matthew Nuzum ,
+	, Rob Fielding 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <905B43ED-A395-11D8-A34F-000393BD6C3E@tuckfield.com>
+Message-ID: 
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+
+On Tue, 11 May 2004, Paul Tuckfield wrote:
+
+> Love that froogle.
+> 
+> It looks like a nice card.     One thing I didn't get straight is if 
+> the cache is writethru or write back.
+> 
+> If the original posters problem is truly a burst write problem (and not 
+> linux caching or virtual memory overcommitment) then writeback is key.
+
+the MegaRaid can be configured either way.  it defaults to writeback if 
+the battery backed cache is present, I believe.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:09:23 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 11 May 2004 16:08:33 -0600 (MDT)
+Date: Tue, 11 May 2004 16:08:20 -0600 (MDT)
+From: "scott.marlowe" 
+To: Rob Sell 
+Cc: 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+In-Reply-To: <20040511214712.0C48D33B9@mail.facnd.com>
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+
+On Tue, 11 May 2004, Rob Sell wrote:
+
+
+> 
+> If you don't mind slumming on ebay :-) keep an eye out for PERC III cards,
+> they are dell branded LSI cards. Perc = Power Edge Raid Controller. There
+> are models on there dual channel u320 and dell usually sells them with
+> battery backed cache.  That's how I have acquired all my high end raid
+> cards.
+
+Not all Perc3s are lsi, many are adaptec.  The perc3di is adaptec, the 
+perc3dc is lsi/megaraid.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:10:52 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Tue, 11 May 2004 18:10:29 -0400 (EDT)
+	(envelope-from jcoene@gotfrag.com)
+Message-Id: <200405112210.i4BMASam015217@mail.gotfrag.com>
+From: "Jason Coene" 
+To: 
+Subject: Intermittent slowdowns, connection delays
+Date: Tue, 11 May 2004 18:10:30 -0400
+MIME-Version: 1.0
+Content-Type: multipart/mixed;
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+
+------=_NextPart_000_002C_01C43783.3EB43F20
+Content-Type: text/plain;
+	charset="US-ASCII"
+Content-Transfer-Encoding: 7bit
+
+Hi All,
+
+We have a Postgres 7.4.1 server running on FreeBSD 5.2.  Hardware is a Dual
+Xeon 2.6 (HT enabled), 2 GB Memory, 3Ware SATA RAID-5 w/ 4 7200 RPM Seagate
+disks and gigabit Intel Server Ethernet.  The server is dedicated to serving
+data to our web-based CMS.
+
+We have a few web servers load balanced, and we do around 1M page
+impressions per day.  Our website is highly personalized, and we've
+optimized it to limit the number of queries, but we still see between 2 and
+3 SELECT's (with JOIN's) and 1 UPDATE per page load, selectively more - a
+fair volume.
+
+The single UPDATE per page load is updating a timestamp in a small table
+(about 150,000 rows) with only 1 index (on the 1 field that needs to be
+matched).
+
+We're seeing some intermittent spikes in query time as actual connection
+time.  I.e., during these seemingly random spikes, our debug output looks
+like this (times from start of HTTP request):
+
+SQL CONNECTION CREATING 'gf'
+0.0015 - ESTABLISHING CONNECTION
+1.7113 - CONNECTION OK
+SQL QUERY ID 1 COST 0.8155 ROWS 1
+SQL QUERY ID 2 COST 0.5607 ROWS 14
+.. etc.. (all queries taking more time than normal, see below)
+
+Refresh the page 2 seconds later, and we'll get:
+
+SQL CONNECTION CREATING 'gf'
+0.0017 - ESTABLISHING CONNECTION
+0.0086 - CONNECTION OK
+SQL QUERY ID 1 COST 0.0128 ROWS 1
+SQL QUERY ID 2 COST 0.0033 ROWS 14
+.. etc.. (with same queries)
+
+Indeed, during these types, it takes a moment for "psql" to connect on the
+command line (from the same machine using a local file socket), so it's not
+a network issue or a web-server issue.  During these spurts, there's nothing
+too out of the ordinary in vmstat, systat or top.
+
+These programs show that we're not using much CPU (usually 60-80% idle), and
+disks usage is virtually nil.  I've attached 60 seconds of "vmstat 5".
+Memory usage looks like this (constantly):
+
+Mem: 110M Active, 1470M Inact, 206M Wired, 61M Cache, 112M Buf, 26M Free
+
+I've cleaned up and tested query after query, and nothing is a "hog".  On an
+idle server, every query will execute in < 0.05 sec.  Perhaps some of you
+veterans have ideas?
+
+Thanks,
+
+Jason Coene
+Gotfrag eSports
+585-598-6621 Phone
+585-598-6633 Fax
+jcoene@gotfrag.com
+http://www.gotfrag.com
+
+
+
+------=_NextPart_000_002C_01C43783.3EB43F20
+Content-Type: text/plain;
+	name="vmstat51min.txt"
+Content-Transfer-Encoding: quoted-printable
+Content-Disposition: attachment;
+	filename="vmstat51min.txt"
+
+d01.gotfrag.com> vmstat 5
+ procs      memory      page                    disks     faults      cpu
+ r b w     avm    fre  flt  re  pi  po  fr  sr tw0 fd0   in   sy  cs us sy =
+id
+ 0 9 5  335952 103108  625   0   0   0 319   4   0   0  584    0 437  3  5 =
+92
+ 0 4 5  350772  90140 24534   0   0   0 2533   0   8   0 1448    0 45969  8=
+ 22 71
+ 0 0 0  321016 112884 10603   0   0   0 2840   0   3   0 2030    0 26562  6=
+ 12 82
+ 0 0 0  341428  99548 10823   0   0   0 1014   0   4   0  687    0 4891  4 =
+ 5 91
+ 0 0 0  352064  91748 13041   0   0   0 1979   0   6   0  743    0 4950  6 =
+ 6 88
+ 0 0 0  346236  96024 7562   0   0   0 2070   0   2   0  736    0 2057  4  =
+3 93
+ 0 1 0  366876  82184 10081   0   0   0 1502   0  50   0  828    0 2607  5 =
+ 5 90
+ 0 0 0  321600 112344 9724   0   0   0 3984   0   1   0  885    0 3440  5  =
+5 90
+ 2 0 0  321200 112716 24244   0   0   0 2571   0   8   0  794    0 33756  8=
+ 17 75
+ 0 0 1  329016 107352 16676   0   0   0 2834   0  10   0  922    0 44430  9=
+ 20 71
+ 0 0 0  328620 107328 13862   0   0   0 1713   0   2   0  616    0 8500  4 =
+ 7 90
+ 0 0 0  317376 114780 3798   0   0   0 1321   0   0   0  514    0 1137  2  =
+2 97
+ 0 5 0  334724 102396 12999   0   0   0 1106   0  39   0  672    0 24891  5=
+ 13 82
+ 0 3 3  336904 102068 12886   0   0   0 2527   0  29   0  879    0 18817  6=
+ 10 84
+ 2 0 0  324008 110416 14625   0   0   0 2378   0   4   0  745    0 28433  7=
+ 14 79
+ 0 0 4  333692 104400 15440   0   0   0 1154   0   7   0  645    0 31156  4=
+ 16 80
+ 4 12 0  352328  91884 19349   0   0   0 1095   0   5   0  623    0 46283  =
+9 21 70
+ 5 5 0  345796  95412 15790   0   0   0 1896   0   2   0  727    0 50062 10=
+ 20 70
+ 4 1 0  331440 105316 16178   0   0   0 2909   0   5   0 1728    0 48194  9=
+ 20 71
+ 0 0 0  326664 108364 11869   0   0   0 1533   0  61   0  640    0 11855  5=
+  9 85
+ 0 0 2  322980 110452 5970   0   0   0 1520   0   0   0  594    0 1614  3  =
+3 95
+ 0 10 6  343108  97884 17571   0   0   0 1409   0  14   0  643    0 33528  =
+6 18 76
+------=_NextPart_000_002C_01C43783.3EB43F20--
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:17:02 2004
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+To: pgsql-performance@postgresql.org
+Subject: Re: Quad processor options
+Message-ID: <20040511221315.GA12117@lifeintegrity.com>
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+From: allanwind@lifeintegrity.com (Allan Wind)
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+
+On 2004-05-11T15:29:46-0600, scott.marlowe wrote:
+> The other nice thing about the LSI cards is that you can install >1 and=
+=20
+> the act like one big RAID array.  i.e. install two cards with a 20 drive=
+=20
+> RAID0 then make a RAID1 across them, and if one or the other cards itself=
+=20
+> fails, you've still got 100% of your data sitting there.  Nice to know yo=
+u=20
+> can survive the complete failure of one half of your chain.
+
+... unless that dying controller corrupted your file system.  Depending
+on your tolerance for risk, you may not want to operate for long with a
+file system in an unknown state.
+
+Btw, the Intel and LSI Logic RAID controller cards have suspeciously
+similar specificationsi, so I would be surprised if one is an OEM.
+
+
+/Allan
+--=20
+Allan Wind
+P.O. Box 2022
+Woburn, MA 01888-0022
+USA
+
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+From pgsql-performance-owner@postgresql.org  Tue May 11 19:24:23 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Subject: Re: Quad processor options
+From: "J. Andrew Rogers" 
+To: Bjoern Metzdorf ,
+	pgsql-performance@postgresql.org
+In-Reply-To: <40A12452.3040505@turtle-entertainment.de>
+References: <40A12452.3040505@turtle-entertainment.de>
+Content-Type: text/plain
+Organization: 
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+
+On Tue, 2004-05-11 at 12:06, Bjoern Metzdorf wrote:
+> Has anyone experiences with quad Xeon or quad Opteron setups? I am 
+> looking at the appropriate boards from Tyan, which would be the only 
+> option for us to buy such a beast. The 30k+ setups from Dell etc. don't 
+> fit our budget.
+> 
+> I am thinking of the following:
+> 
+> Quad processor (xeon or opteron)
+> 5 x SCSI 15K RPM for Raid 10 + spare drive
+> 2 x IDE for system
+> ICP-Vortex battery backed U320 Hardware Raid
+> 4-8 GB Ram
+
+
+Just to add my two cents to the fray:
+
+We use dual Opterons around here and prefer them to the Xeons for
+database servers.  As others have pointed out, the Opteron systems will
+scale well to more than two processors unlike the Xeon.  I know a couple
+people with quad Opterons and it apparently scales very nicely, unlike
+quad Xeons which don't give you much more.  On some supercomputing
+hardware lists I'm on, they seem to be of the opinion that the current
+Opteron fabric won't really show saturation until you have 6-8 CPUs
+connected to it.
+
+Like the other folks said, skip the 15k drives.  Those will only give
+you a marginal improvement for an integer factor price increase over 10k
+drives.  Instead spend your money on a nice RAID controller with a fat
+cache and a backup battery, and maybe some extra spindles for your
+array.  I personally like the LSI MegaRAID 320-2, which I always max out
+to 256Mb of cache RAM and the required battery.  A maxed out LSI 320-2
+should set you back <$1k.  Properly configured, you will notice large
+improvements in the performance of your disk subsystem, especially if
+you have a lot of writing going on.
+
+I would recommend getting the Opterons, and spending the relatively
+modest amount of money to get nice RAID controller with a large
+write-back cache while sticking with 10k drives.
+
+Depending on precisely how you configure it, this should cost you no
+more than $10-12k.  We just built a very similar configuration, but with
+dual Opterons on an HDAMA motherboard rather than a quad Tyan, and it
+cost <$6k inclusive of everything.  Add the money for 4 of the 8xx
+processors and the Tyan quad motherboard, and the sum comes out to a
+very reasonable number for what you are getting.
+
+
+j. andrew rogers
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:33:01 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Subject: Re: Configuring PostgreSQL to minimize impact of
+From: "J. Andrew Rogers" 
+To: Paul Tuckfield ,
+	pgsql-performance@postgresql.org
+In-Reply-To: <905B43ED-A395-11D8-A34F-000393BD6C3E@tuckfield.com>
+References: 
+	<905B43ED-A395-11D8-A34F-000393BD6C3E@tuckfield.com>
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+
+On Tue, 2004-05-11 at 14:52, Paul Tuckfield wrote:
+> Love that froogle.
+> 
+> It looks like a nice card.     One thing I didn't get straight is if 
+> the cache is writethru or write back.
+
+
+The LSI MegaRAID reading/writing/caching behavior is user configurable.
+It will support both write-back and write-through, and IIRC, three
+different algorithms for reading (none, read-ahead, adaptive).  Plenty
+of configuration options.
+
+It is a pretty mature and feature complete hardware RAID implementation.
+
+
+j. andrew rogers
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 19:53:41 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Tue, 11 May 2004 16:44:34 -0600 (MDT)
+Date: Tue, 11 May 2004 16:44:21 -0600 (MDT)
+From: "scott.marlowe" 
+To: Allan Wind 
+Cc: 
+Subject: Re: Quad processor options
+In-Reply-To: <20040511221315.GA12117@lifeintegrity.com>
+Message-ID: 
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+
+On Tue, 11 May 2004, Allan Wind wrote:
+
+> On 2004-05-11T15:29:46-0600, scott.marlowe wrote:
+> > The other nice thing about the LSI cards is that you can install >1 and 
+> > the act like one big RAID array.  i.e. install two cards with a 20 drive 
+> > RAID0 then make a RAID1 across them, and if one or the other cards itself 
+> > fails, you've still got 100% of your data sitting there.  Nice to know you 
+> > can survive the complete failure of one half of your chain.
+> 
+> ... unless that dying controller corrupted your file system.  Depending
+> on your tolerance for risk, you may not want to operate for long with a
+> file system in an unknown state.
+
+It would have to be the primary controller for that to happen.  The way 
+the LSI's work is that you disable the BIOS on the 2nd to 4th cards, and 
+the first card, with the active BIOS acts as the primary controller.
+
+In this case, that means the main card is doing the RAID1 work, then 
+handing off the data to the subordinate cards.
+
+The subordinate cards do all their own RAID0 work.
+
+mobo ---controller 1-- Btw, the Intel and LSI Logic RAID controller cards have suspeciously
+> similar specificationsi, so I would be surprised if one is an OEM.
+
+Hmmm.  I'll take a closer look.
+
+
+From pgsql-admin-owner@postgresql.org  Tue May 11 19:53:41 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+References: 
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+Cc: "Pgsql-Admin (E-mail)" ,
+	"scott.marlowe" , pgsql-performance@postgresql.org
+From: Paul Tuckfield 
+Subject: Re: [PERFORM] Quad processor options
+Date: Tue, 11 May 2004 15:46:25 -0700
+To: Bjoern Metzdorf 
+X-Mailer: Apple Mail (2.613)
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+I'm confused why you say the system is 70% busy: the vmstat output 
+shows 70% *idle*.
+
+The vmstat you sent shows good things and ambiguous things:
+- si and so are zero, so your not paging/swapping.  Thats always step 
+1.  you're fine.
+- bi and bo (physical IO) shows pretty high numbers for how many disks 
+you have.
+   (assuming random IO) so please send an "iostat 10" sampling during 
+peak.
+- note that cpu is only 30% busy.  that should mean that adding cpus 
+will *not* help.
+- the "cache" column shows that linux is using 2.3G for cache. (way too 
+much)
+   you generally want to give memory to postgres to keep it "close" to 
+the user,
+   not leave it unused to be claimed by linux cache (need to leave 
+*some* for linux tho)
+
+My recommendations:
+- I'll bet you have a low value for shared buffers, like 10000.  On 
+your 3G system
+   you should ramp up the value to at least 1G (125000 8k buffers) 
+unless something
+   else runs on the system.   It's best to not do things too 
+drastically, so if Im right and
+   you sit at 10000 now, try going to 30000 then 60000 then 125000 or 
+above.
+
+- if the above is off base, then I wonder why we see high runque 
+numbers in spite
+   of over 60% idle cpu.   Maybe some serialization happening somewhere. 
+  Also depending
+   on how you've laid out your 4 disk drives, you may see all IOs going 
+to one drive. the 7M/sec
+   is on the high side, if that's the case.  iostat numbers will reveal 
+if it's skewed, and if it's random,
+  tho linux iostat doesn't seem to report response times (sigh)   
+Response times are the golden
+  metric when diagnosing IO thruput in OLTP / stripe situation.
+
+
+
+
+On May 11, 2004, at 1:41 PM, Bjoern Metzdorf wrote:
+
+> scott.marlowe wrote:
+>
+>> Well, from what I've read elsewhere on the internet, it would seem 
+>> the Opterons scale better to 4 CPUs than the basic Xeons do.  Of 
+>> course, the exception to this is SGI's altix, which uses their own 
+>> chipset and runs the itanium with very good memory bandwidth.
+>
+> This is basically what I read too. But I cannot spent money on a quad 
+> opteron just for testing purposes :)
+>
+>> But, do you really need more CPU horsepower?
+>> Are you I/O or CPU or memory or memory bandwidth bound?  If you're 
+>> sitting at 99% idle, and iostat says your drives are only running at 
+>> some small percentage of what you know they could, you might be 
+>> memory or memory bandwidth limited.  Adding two more CPUs will not 
+>> help with that situation.
+>
+> Right now we have a dual xeon 2.4, 3 GB Ram, Mylex extremeraid 
+> controller, running 2 Compaq BD018122C0, 1 Seagate ST318203LC and 1 
+> Quantum ATLAS_V_18_SCA.
+>
+> iostat show between 20 and 60 % user avg-cpu. And this is not even 
+> peak time.
+>
+> I attached a "vmstat 10 120" output for perhaps 60-70% peak load.
+>
+>> If your I/O is saturated, then the answer may well be a better RAID 
+>> array, with many more drives plugged into it.  Do you have any spare 
+>> drives you can toss on the machine to see if that helps?  Sometimes 
+>> going from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big 
+>> boost in performance.
+>
+> Next drives I'll buy will certainly be 15k scsi drives.
+>
+>> In short, don't expect 4 CPUs to solve the problem if the problem 
+>> isn't really the CPUs being maxed out.
+>> Also, what type of load are you running?  Mostly read, mostly 
+>> written, few connections handling lots of data, lots of connections 
+>> each handling a little data, lots of transactions, etc...
+>
+> In peak times we can get up to 700-800 connections at the same time. 
+> There are quite some updates involved, without having exact numbers 
+> I'll think that we have about 70% selects and 30% updates/inserts.
+>
+>> If you are doing lots of writing, make SURE you have a controller 
+>> that supports battery backed cache and is configured to write-back, 
+>> not write-through.
+>
+> Could you recommend a certain controller type? The only battery backed 
+> one that I found on the net is the newest model from icp-vortex.com.
+>
+> Regards,
+> Bjoern
+> ~# vmstat 10 120
+>    procs                      memory    swap          io     system    
+>      cpu
+>  r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  
+> us  sy  id
+>  1  1  0  24180  10584  32468 2332208   0   1     0     2    1     2   
+> 2   0   0
+>  0  2  0  24564  10480  27812 2313528   8   0  7506   574 1199  8674  
+> 30   7  63
+>  2  1  0  24692  10060  23636 2259176   0  18  8099   298 2074  6328  
+> 25   7  68
+>  2  0  0  24584  18576  21056 2299804   3   6 13208   305 1598  8700  
+> 23   6  71
+>  1 21  1  24504  16588  20912 2309468   4   0  1442  1107  754  6874  
+> 42  13  45
+>  6  1  0  24632  13148  19992 2319400   0   0  2627   499 1184  9633  
+> 37   6  58
+>  5  1  0  24488  10912  19292 2330080   5   0  3404   150 1466 10206  
+> 32   6  61
+>  4  1  0  24488  12180  18824 2342280   3   0  2934    40 1052  3866  
+> 19   3  78
+>  0  0  0  24420  14776  19412 2347232   6   0   403   216 1123  4702  
+> 22   3  74
+>  0  0  0  24548  14408  17380 2321780   4   0   522   715  965  6336  
+> 25   5  71
+>  4  0  0  24676  12504  17756 2322988   0   0   564   830  883  7066  
+> 31   6  63
+>  0  3  0  24676  14060  18232 2325224   0   0   483   388 1097  3401  
+> 21   3  76
+>  0  2  1  24676  13044  18700 2322948   0   0   701   195 1078  5187  
+> 23   3  74
+>  2  0  0  24676  21576  18752 2328168   0   0   467   177 1552  3574  
+> 18   3  78
+>
+> ---------------------------(end of 
+> broadcast)---------------------------
+> TIP 2: you can get off all lists at once with the unregister command
+>     (send "unregister YourEmailAddressHere" to 
+> majordomo@postgresql.org)
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 11 22:06:56 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-Id: <200405120104.i4C14Fam018939@mail.gotfrag.com>
+From: "Jason Coene" 
+To: "'Paul Tuckfield'" 
+Cc: 
+Subject: Re: Intermittent slowdowns, connection delays
+Date: Tue, 11 May 2004 21:04:16 -0400
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+
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+
+Hi Paul,
+
+Thanks for the valuable feedback.  I suspect you're correct about the
+serialization in some capacity, but the actual cause is eluding me.
+
+Basically, every time a registered user checks a page, the site has to
+authenticate them (with a query against a table with > 200,000 records).  It
+doesn't update this table, however - it updates another table with "user
+stats" information (last click, last ip, etc).
+
+ From what I've seen, there doesn't seem to be any serious locking issues.
+It does make sense when a number of users whose information isn't in cache,
+it could take a bit longer - but AFAIK this shouldn't prevent other
+simultaneous queries.  What else could cause such serialization?
+
+If I look at open locks (this is a view, info from pg tables):
+
+       relname        |       mode       | numlocks
+----------------------+------------------+----------
+ users                | AccessShareLock  |        4
+ userstats            | AccessShareLock  |        4
+ pg_statistic         | AccessShareLock  |        2
+ users_ix_id          | AccessShareLock  |        2
+ countries            | AccessShareLock  |        2
+ comments             | AccessShareLock  |        2
+ countries_ix_id      | AccessShareLock  |        2
+ userstats_ix_id      | AccessShareLock  |        2
+ comments_ix_parentid | AccessShareLock  |        2
+ users                | RowExclusiveLock |        1
+ filequeue_ix_id      | AccessShareLock  |        1
+ pg_class             | AccessShareLock  |        1
+ vopenlocks           | AccessShareLock  |        1
+ pg_locks             | AccessShareLock  |        1
+ userstats            | RowExclusiveLock |        1
+ filequeue            | AccessShareLock  |        1
+ pg_class_oid_index   | AccessShareLock  |        1
+
+Also of note, executing a random "in the blue" query on our "users" table
+returns results very fast.  While there's no doubt that caching may help,
+returning a row that is definitely not cached is very fast: < 0.05 sec.
+
+Top tells me that the system isn't using much memory - almost always under
+100MB (of the 2GB we have).  Is there a way to increase the amount of
+physical RAM that PG uses?  It seems there's a lot of room there.
+
+Postgresql.conf has:
+
+shared_buffers = 16384
+sort_mem = 8192
+vacuum_mem = 8192
+
+Also, would queries becoming serialized effect connection delays?  I think
+there's still something else at large here...
+
+I've attached a vmstat output, while running dd.  The RAID array is tw0.  It
+does show the tw0 device getting significantly more work, numbers not seen
+during normal operation.
+
+Thanks,
+
+Jason Coene
+Gotfrag eSports
+585-598-6621 Phone
+585-598-6633 Fax
+jcoene@gotfrag.com
+http://www.gotfrag.com
+
+
+-----Original Message-----
+From: Paul Tuckfield [mailto:paul@tuckfield.com] 
+Sent: Tuesday, May 11, 2004 7:50 PM
+To: Jason Coene
+Subject: Re: [PERFORM] Intermittent slowdowns, connection delays
+
+The things you point out suggest a heavy dependence on good cache 
+performance
+(typical of OLTP mind you)  Do not be fooled if a query runs in 2 
+seconds then the second
+run takes < .01 secons:  the first run put it in cache the second got 
+all cache hits :)
+
+But beyond that,  in an OLTP system, and typical website backing 
+database, "cache is king".
+And serialization is the devil
+
+So look for reasons why your cache performance might deteriorate during 
+peak, (like large historical tables
+that users pull up dozens of scattered rows from, flooding cache)  or 
+why you may be
+serializing somewhere inside postgres (ex. if every page hit re-logs 
+in, then theres probably serialization
+trying to spawn what must be 40 processes/sec assuming your 11hit/sec 
+avg peaks at about 40/sec)
+
+Also:
+I am really surprised you see zero IO in the vmstat you sent, but I'm 
+unfamiliar with BSD version of vmstat.
+AFAIR,  Solaris shows cached filesystem reads as "page faults" which is 
+rather confusing.  Since you have 1500 page
+faults per second, yet no paging (bi bo) does thins mean the 1500 page 
+faults are filesystem IO that pg is doing?
+do an objective test on an idle system by dd'ing a large file in and 
+watching what vmstat does.
+
+
+
+
+
+On May 11, 2004, at 3:10 PM, Jason Coene wrote:
+
+> Hi All,
+>
+> We have a Postgres 7.4.1 server running on FreeBSD 5.2.  Hardware is a 
+> Dual
+> Xeon 2.6 (HT enabled), 2 GB Memory, 3Ware SATA RAID-5 w/ 4 7200 RPM 
+> Seagate
+> disks and gigabit Intel Server Ethernet.  The server is dedicated to 
+> serving
+> data to our web-based CMS.
+>
+> We have a few web servers load balanced, and we do around 1M page
+> impressions per day.  Our website is highly personalized, and we've
+> optimized it to limit the number of queries, but we still see between 
+> 2 and
+> 3 SELECT's (with JOIN's) and 1 UPDATE per page load, selectively more 
+> - a
+> fair volume.
+>
+> The single UPDATE per page load is updating a timestamp in a small 
+> table
+> (about 150,000 rows) with only 1 index (on the 1 field that needs to be
+> matched).
+>
+> We're seeing some intermittent spikes in query time as actual 
+> connection
+> time.  I.e., during these seemingly random spikes, our debug output 
+> looks
+> like this (times from start of HTTP request):
+>
+> SQL CONNECTION CREATING 'gf'
+> 0.0015 - ESTABLISHING CONNECTION
+> 1.7113 - CONNECTION OK
+> SQL QUERY ID 1 COST 0.8155 ROWS 1
+> SQL QUERY ID 2 COST 0.5607 ROWS 14
+> .. etc.. (all queries taking more time than normal, see below)
+>
+> Refresh the page 2 seconds later, and we'll get:
+>
+> SQL CONNECTION CREATING 'gf'
+> 0.0017 - ESTABLISHING CONNECTION
+> 0.0086 - CONNECTION OK
+> SQL QUERY ID 1 COST 0.0128 ROWS 1
+> SQL QUERY ID 2 COST 0.0033 ROWS 14
+> .. etc.. (with same queries)
+>
+> Indeed, during these types, it takes a moment for "psql" to connect on 
+> the
+> command line (from the same machine using a local file socket), so 
+> it's not
+> a network issue or a web-server issue.  During these spurts, there's 
+> nothing
+> too out of the ordinary in vmstat, systat or top.
+>
+> These programs show that we're not using much CPU (usually 60-80% 
+> idle), and
+> disks usage is virtually nil.  I've attached 60 seconds of "vmstat 5".
+> Memory usage looks like this (constantly):
+>
+> Mem: 110M Active, 1470M Inact, 206M Wired, 61M Cache, 112M Buf, 26M 
+> Free
+>
+> I've cleaned up and tested query after query, and nothing is a "hog".  
+> On an
+> idle server, every query will execute in < 0.05 sec.  Perhaps some of 
+> you
+> veterans have ideas?
+>
+> Thanks,
+>
+> Jason Coene
+> Gotfrag eSports
+> 585-598-6621 Phone
+> 585-598-6633 Fax
+> jcoene@gotfrag.com
+> http://www.gotfrag.com
+>
+>
+> 
+> ---------------------------(end of 
+> broadcast)---------------------------
+> TIP 6: Have you searched our list archives?
+>
+>                http://archives.postgresql.org
+
+
+------=_NextPart_000_0008_01C4379B.858F34F0
+Content-Type: text/plain;
+	name="vmstatdd.txt"
+Content-Transfer-Encoding: quoted-printable
+Content-Disposition: attachment;
+	filename="vmstatdd.txt"
+
+(dd if=3D/dev/zero of=3DX and vmstat 1)
+
+ procs      memory      page                    disks     faults      cpu
+ r b w     avm    fre  flt  re  pi  po  fr  sr tw0 fd0   in   sy  cs us sy =
+id
+ 1 0 0  245496 294952  652   0   0   0 322   4   0   0  584    0 481  3  5 =
+92
+ 0 0 1  245772 294892 10681   0   0   0 2380   0   0   0  780    0 1634  4 =
+ 4 92
+ 0 0 0  248404 293132 6783   0   0   0 1220   0   4   0  641    0 2005  3  =
+4 93
+ 0 0 0  243740 296180   89   0   0   0 780   0   0   0  363    0 1038  0  1=
+ 99
+ 0 0 0  247576 293808 4253   0   0   1 897   0   1   0  568    0 1082  2  2=
+ 97
+ 0 0 0  243740 296172 1142   0   0   0 1009   0   0   0  408    0 681  1  1=
+ 99
+ 0 0 0  246072 294572 7128   0   0   0 1495   0   2   0  981    0 2501  4  =
+3 93
+ 4 0 0  248988 278004 3977   0   0   0 1292   0 117   0  672    0 6082  2 1=
+1 87		<-begin dd
+ 0 0 4  253156 254952 19216   0   0   0 381   0 161   0  657    0 26432  4 =
+22 74
+ 8 1 0  256124 239764 23349   0   0   0 827   0 115   0  621    0 32020  5 =
+22 73
+ 0 6 4  263236 212068 9642   0   0   0 579   0 174   0  745    0 28661  4 2=
+5 71
+ 0 0 13  269392 193476 9983   0   0   0 278   0 137   0  685    0 36589  5 =
+24 70
+ 1 6 1  260652 181072 12043   0   0   0 2517   0 130   0  683    0 33646  3=
+ 25 72
+ 0 2 7  265188 162412 7449   0   0   0  39   0 127   0  615    0 38233  6 2=
+0 73
+ 4 6 0  266368 144724 8641   0   0   0 822   0 133   0  624    0 35629  5 2=
+3 72
+ 0 8 3  268884 125808 4609   0   0   0 703   0 138   0  659    0 38966  3 2=
+4 73
+ 7 6 3  271564 111468 19948   0   0   0 1106   0  97   0  589    0 39840  4=
+ 25 71
+ 0 19 3  283872  87824 14926   0   0   0  61   0 105   0  736    0 48359  4=
+ 25 71
+ 0 12 10  291640 109440 7975  12   0   0 3469 11675 147   0  794    0 33581=
+  6 25 69
+ 8 14 0  292732  89640 11033   6   0   0 6700   0 149   0  782    0 28399  =
+6 24 70
+ 4 10 0  293364  71488 13177   0   0   0 8696   0 154   0 2623    0 29119  =
+9 22 69
+ 1 5 0  271656  67016 8240   0   0   0 6490   0 170   0 4574    0 30951  5 =
+25 70
+ 0 0 3  262840  99200 15399   0   0   0 6278 10814 145   0  879    0 21206 =
+ 5 22 73
+ 0 4 0  261216  95812 12921   0   0   0 1830   0 147   0  595    0 13402  3=
+  9 87
+ 1 6 0  262204  95228 1843   0   0   0 863   0 119   0  580    0 1266  1  1=
+ 98
+ 0 1 4  265508  82648 15552   0   0   0 4328   0 132   0  736    0 22650  3=
+ 18 78
+ 0 0 6  259920  76580 19770   0   0   0 2761   0  90   0  514    0 37724  3=
+ 24 72
+ 7 0 4  261600  67540 10702   0   0   0 2718   0  62   0  536    0 53733  4=
+ 24 71
+ 0 8 6  269752  98244 7281   0   0   0 5609 13252 139   0  614    0 40253  =
+3 27 70	<- end dd
+ 6 10 0  274424  73056 6511   0   0   0 6758   0 161   0  673    0 33534  5=
+ 24 71
+ 0 8 5  283500 111436 20968   0   0   0 3808 12137  36   0  848    0 42361 =
+ 7 22 70
+ 0 10 6  287016 457036 16186   0   0   0 89317   0  11   0  736    0 55810 =
+13 29 58
+ 4 15 0  293108 451540 18923   0   0   0 1156   0   8   0  725    0 53572 1=
+3 22 64
+ 0 6 4  279592 460536 22728   0   0   0 4110   0   6   0  782    0 26818 15=
+ 15 69
+------=_NextPart_000_0008_01C4379B.858F34F0--
+
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 01:04:08 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP
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+	id A853A8332; Wed, 12 May 2004 06:03:41 +0200 (CEST)
+Date: Wed, 12 May 2004 06:03:41 +0200 (CEST)
+From: Dennis Bjorklund 
+To: Bjoern Metzdorf 
+Cc: pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+In-Reply-To: <40A12452.3040505@turtle-entertainment.de>
+Message-ID: 
+MIME-Version: 1.0
+Content-Type: TEXT/PLAIN; charset=ISO-8859-1
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+
+On Tue, 11 May 2004, Bjoern Metzdorf wrote:
+
+> I am curious if there are any real life production quad processor setups 
+> running postgresql out there. Since postgresql lacks a proper 
+> replication/cluster solution, we have to buy a bigger machine.
+
+Du you run the latest version of PG? I've read the thread bug have not 
+seen any information about what pg version. All I've seen was a reference 
+to debian which might just as well mean that you run pg 7.2 (probably not 
+but I have to ask).
+
+Some classes of queries run much faster in pg 7.4 then in older versions
+so if you are lucky that can help.
+
+-- 
+/Dennis Bj�rklund
+
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 01:59:08 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	with ESMTP id 41812-01; Wed, 12 May 2004 01:58:44 -0300 (ADT)
+Received: from elbereth.noviforum.si (unknown [193.189.169.66])
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+	Wed, 12 May 2004 06:58:32 +0200
+Date: Wed, 12 May 2004 06:58:32 +0200
+From: Grega Bremec 
+To: "scott.marlowe" 
+Cc: Bjoern Metzdorf ,
+	pgsql-performance@postgresql.org,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+Message-ID: <20040512045832.GA10035@elbereth.noviforum.si>
+References: <40A13A78.9000607@turtle-entertainment.de>
+	
+Mime-Version: 1.0
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+	protocol="application/pgp-signature"; boundary="UugvWAfsgieZRqgk"
+Content-Disposition: inline
+In-Reply-To: 
+User-Agent: Mutt/1.4.2i
+Organization: Noviforum, Ltd., Software & Media
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+--UugvWAfsgieZRqgk
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline
+Content-Transfer-Encoding: quoted-printable
+
+...and on Tue, May 11, 2004 at 03:02:24PM -0600, scott.marlowe used the key=
+board:
+>=20
+> If you get the LSI megaraid, make sure you're running the latest megaraid=
+=20
+> 2 driver, not the older, slower 1.18 series.  If you are running linux,=
+=20
+> look for the dkms packaged version.  dkms, (Dynamic Kernel Module System)=
+=20
+> automagically compiles and installs source rpms for drivers when you=20
+> install them, and configures the machine to use them to boot up.  Most=20
+> drivers seem to be slowly headed that way in the linux universe, and I=20
+> really like the simplicity and power of dkms.
+>=20
+
+Hi,
+
+Given the fact LSI MegaRAID seems to be a popular solution around here, and
+many of you folx use Linux as well, I thought sharing this piece of info
+might be of use.
+
+Running v2 megaraid driver on a 2.4 kernel is actually not a good idea _at_
+_all_, as it will silently corrupt your data in the event of a disk failure.
+
+Sorry to have to say so, but we tested it (on kernels up to 2.4.25, not sure
+about 2.4.26 yet) and it comes out it doesn't do hotswap the way it should.
+
+Somehow the replaced disk drives are not _really_ added to the array, which
+continues to work in degraded mode for a while and (even worse than that)
+then starts to think the replaced disk is in order without actually having
+resynced it, thus beginning to issue writes to non-existant areas of it.
+
+The 2.6 megaraid driver indeed seems to be a merged version of the above
+driver and the old one, giving both improved performance and correct
+functionality in the event of a hotswap taking place.
+
+Hope this helped,
+--=20
+    Grega Bremec
+    Senior Administrator
+    Noviforum Ltd., Software & Media
+    http://www.noviforum.si/
+
+--UugvWAfsgieZRqgk
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+h4GKg3G3V7U9fnSr5go47zQ=
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+--UugvWAfsgieZRqgk--
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 02:35:05 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+Date: Wed, 12 May 2004 09:34:34 +0400
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+Reply-To: spied@yandex.ru
+X-Priority: 3 (Normal)
+Message-ID: <8886978734.20040512093434@yandex.ru>
+To: pgsql-performance@postgresql.org
+Subject: Re: Quad processor options
+In-Reply-To: <40A13BAB.5080500@turtle-entertainment.de>
+References: <40A12452.3040505@turtle-entertainment.de>
+	
+	<40A13BAB.5080500@turtle-entertainment.de>
+MIME-Version: 1.0
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+
+BM> see my other mail.
+
+BM> We are running Linux, Kernel 2.4. As soon as the next debian version 
+BM> comes out, I'll happily switch to 2.6 :)
+
+it's very simple to use 2.6 with testing version, but if you like
+woody - you can simple install several packets from testing or
+backports.org
+
+if you think about perfomance you must use lastest version of
+postgresql server - it can be installed from testing or backports.org
+too (but postgresql from testing depend from many other testing
+packages).
+
+i think if you upgade existing system you can use backports.org for
+nevest packages, if you install new - use testing - it can be used
+on production servers today
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 03:11:35 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+From: "Michael Ryan S. Puncia" 
+To: 
+Subject: Using LIKE expression problem..
+Date: Wed, 12 May 2004 14:18:48 +0800
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+
+Hi everybody..
+
+    
+
+     Before anything else I would like to thank all those person who answers
+my previous question. again thank you very much
+
+ 
+
+This is my question .
+
+    
+
+     In my query .. Select * from table1 where lastname LIKE  'PUNCIA%'..
+
+ 
+
+In the query plan ..it uses seq scan rather than index scan .. why ? I have
+index on lastname, firtname. 
+
+ 
+
+ 
+
+Thanks
+
+
+------=_NextPart_000_0000_01C4382C.0E830300
+Content-Type: text/html;
+	charset="us-ascii"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+
+
+
+
+
+
+

+
+
Hi everybody..

+
+
    

+
+
     Before anything else I would li=
+ke to thank all those
+person who answers my previous question… again thank you very much

+
+
 

+
+
This is my question …

+
+
    

+
+
     In my query .. Select * from ta=
+ble1 where lastname LIKE
+ ‘PUNCIA%’..

+
+
 

+
+
In the query plan ..it uses seq scan rather than index s=
+can
+.. why ? I have index on lastname, firtname… 

+
+
 

+
+
 

+
+
Thanks

+
+

+
+
+
+
+
+------=_NextPart_000_0000_01C4382C.0E830300--
+
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 03:41:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	i4C6d6WL096552; Wed, 12 May 2004 14:39:07 +0800 (WST)
+	(envelope-from chriskl@familyhealth.com.au)
+Message-ID: <40A1C8BD.8060900@familyhealth.com.au>
+Date: Wed, 12 May 2004 14:48:29 +0800
+From: Christopher Kings-Lynne 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: "Michael Ryan S. Puncia" 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Using LIKE expression problem..
+References: <200405120606.i4C65ph9000939@mail.census.gov.ph>
+In-Reply-To: <200405120606.i4C65ph9000939@mail.census.gov.ph>
+Content-Type: text/plain; charset=windows-1252; format=flowed
+Content-Transfer-Encoding: 8bit
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+X-Spam-Level: 
+X-Archive-Number: 200405/106
+X-Sequence-Number: 6937
+
+> In the query plan ..it uses seq scan rather than index scan .. why ? I 
+> have index on lastname, firtname�
+
+Have you run VACUUM ANALYZE; on the table recently?
+
+Chris
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 04:39:52 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+	Wed, 12 May 2004 15:33:25 +0800
+Message-Id: <200405120733.i4C7XCh9003495@mail.census.gov.ph>
+From: "Michael Ryan S. Puncia" 
+To: "'Christopher Kings-Lynne'" ,
+	"'Michael Ryan S. Puncia'" 
+Cc: 
+Subject: Re: Using LIKE expression problem..
+Date: Wed, 12 May 2004 15:46:07 +0800
+MIME-Version: 1.0
+Content-Type: text/plain;
+	charset="US-ASCII"
+Content-Transfer-Encoding: 7bit
+X-Mailer: Microsoft Office Outlook, Build 11.0.5510
+Thread-Index: AcQ37Pen7Kup97zuSyuPGa0/XTyv+gACBkNw
+In-Reply-To: <40A1C8BD.8060900@familyhealth.com.au>
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+X-Sequence-Number: 6938
+
+Yes , I already do that but the same result .. LIKE uses seq scan
+
+-----Original Message-----
+From: pgsql-performance-owner@postgresql.org
+[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+Kings-Lynne
+Sent: Wednesday, May 12, 2004 2:48 PM
+To: Michael Ryan S. Puncia
+Cc: pgsql-performance@postgresql.org
+Subject: Re: [PERFORM] Using LIKE expression problem..
+
+> In the query plan ..it uses seq scan rather than index scan .. why ? I 
+> have index on lastname, firtname.
+
+Have you run VACUUM ANALYZE; on the table recently?
+
+Chris
+
+
+---------------------------(end of broadcast)---------------------------
+TIP 7: don't forget to increase your free space map settings
+
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 04:51:12 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	(envelope-from chriskl@familyhealth.com.au)
+Message-ID: <40A1D94E.9030605@familyhealth.com.au>
+Date: Wed, 12 May 2004 15:59:10 +0800
+From: Christopher Kings-Lynne 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: "Michael Ryan S. Puncia" 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Using LIKE expression problem..
+References: <200405120733.i4C7XCh9003495@mail.census.gov.ph>
+In-Reply-To: <200405120733.i4C7XCh9003495@mail.census.gov.ph>
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+X-Sequence-Number: 6939
+
+Are you in a non-C locale?
+
+Chris
+
+Michael Ryan S. Puncia wrote:
+
+> Yes , I already do that but the same result .. LIKE uses seq scan
+> 
+> -----Original Message-----
+> From: pgsql-performance-owner@postgresql.org
+> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+> Kings-Lynne
+> Sent: Wednesday, May 12, 2004 2:48 PM
+> To: Michael Ryan S. Puncia
+> Cc: pgsql-performance@postgresql.org
+> Subject: Re: [PERFORM] Using LIKE expression problem..
+> 
+> 
+>>In the query plan ..it uses seq scan rather than index scan .. why ? I 
+>>have index on lastname, firtname.
+> 
+> 
+> Have you run VACUUM ANALYZE; on the table recently?
+> 
+> Chris
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 7: don't forget to increase your free space map settings
+> 
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 05:07:42 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+	Wed, 12 May 2004 16:04:50 +0800
+Message-Id: <200405120804.i4C84gh9004444@mail.census.gov.ph>
+From: "Michael Ryan S. Puncia" 
+To: "'Christopher Kings-Lynne'" ,
+	"'Michael Ryan S. Puncia'" 
+Cc: 
+Subject: Re: Using LIKE expression problem..
+Date: Wed, 12 May 2004 16:17:36 +0800
+MIME-Version: 1.0
+Content-Type: text/plain;
+	charset="US-ASCII"
+Content-Transfer-Encoding: 7bit
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+X-Archive-Number: 200405/109
+X-Sequence-Number: 6940
+
+Sorry .. I am a newbie and I don't know :( 
+How can I know that I am in C locale ?
+How can I change my database to use C locale?
+
+
+
+-----Original Message-----
+From: pgsql-performance-owner@postgresql.org
+[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+Kings-Lynne
+Sent: Wednesday, May 12, 2004 3:59 PM
+To: Michael Ryan S. Puncia
+Cc: pgsql-performance@postgresql.org
+Subject: Re: [PERFORM] Using LIKE expression problem..
+
+Are you in a non-C locale?
+
+Chris
+
+Michael Ryan S. Puncia wrote:
+
+> Yes , I already do that but the same result .. LIKE uses seq scan
+> 
+> -----Original Message-----
+> From: pgsql-performance-owner@postgresql.org
+> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+> Kings-Lynne
+> Sent: Wednesday, May 12, 2004 2:48 PM
+> To: Michael Ryan S. Puncia
+> Cc: pgsql-performance@postgresql.org
+> Subject: Re: [PERFORM] Using LIKE expression problem..
+> 
+> 
+>>In the query plan ..it uses seq scan rather than index scan .. why ? I 
+>>have index on lastname, firtname.
+> 
+> 
+> Have you run VACUUM ANALYZE; on the table recently?
+> 
+> Chris
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 7: don't forget to increase your free space map settings
+> 
+
+---------------------------(end of broadcast)---------------------------
+TIP 5: Have you checked our extensive FAQ?
+
+               http://www.postgresql.org/docs/faqs/FAQ.html
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 22:04:24 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
+	Thu, 13 May 2004 22:04:16 -0300 (ADT)
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+	with ESMTP id 66758-08
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+	Thu, 13 May 2004 22:03:53 -0300 (ADT)
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+	by lamb.mcmillan.net.nz (Postfix) with ESMTP
+	id 4B7DEAE178BF; Wed, 12 May 2004 20:58:13 +1200 (NZST)
+Subject: Re: Quad processor options
+From: Andrew McMillan 
+To: Paul Tuckfield 
+Cc: Bjoern Metzdorf ,
+	pgsql-performance@postgresql.org
+In-Reply-To: <089ED266-A39D-11D8-A34F-000393BD6C3E@tuckfield.com>
+References: 
+	<40A13A78.9000607@turtle-entertainment.de>
+	<089ED266-A39D-11D8-A34F-000393BD6C3E@tuckfield.com>
+Content-Type: text/plain
+Message-Id: <1084352292.4785.37.camel@lamb.mcmillan.net.nz>
+Mime-Version: 1.0
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+Date: Wed, 12 May 2004 20:58:13 +1200
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+X-Spam-Level: 
+X-Archive-Number: 200405/133
+X-Sequence-Number: 6964
+
+On Tue, 2004-05-11 at 15:46 -0700, Paul Tuckfield wrote:
+
+> - the "cache" column shows that linux is using 2.3G for cache. (way too 
+> much) you generally want to give memory to postgres to keep it "close" to 
+> the user, not leave it unused to be claimed by linux cache (need to leave 
+> *some* for linux tho)
+> 
+> My recommendations:
+> - I'll bet you have a low value for shared buffers, like 10000.  On 
+> your 3G system you should ramp up the value to at least 1G (125000 8k buffers) 
+> unless something else runs on the system.   It's best to not do things too 
+> drastically, so if Im right and you sit at 10000 now, try going to
+> 30000 then 60000 then 125000 or above.
+
+Huh?
+
+Doesn't this run counter to almost every piece of PostgreSQL performance
+tuning advice given?
+
+I run my own boxes with buffers set to around 10000-20000 and an
+effective_cache_size = 375000 (8k pages - around 3G).
+
+That's working well with PostgreSQL 7.4.2 under Debian "woody" (using
+Oliver Elphick's backported packages from
+http://people.debian.org/~elphick/debian/).
+
+Regards,
+					Andrew.
+-------------------------------------------------------------------------
+Andrew @ Catalyst .Net .NZ  Ltd,  PO Box 11-053,  Manners St,  Wellington
+WEB: http://catalyst.net.nz/             PHYS: Level 2, 150-154 Willis St
+DDI: +64(4)916-7201       MOB: +64(21)635-694      OFFICE: +64(4)499-2267
+Q:        How much does it cost to ride the Unibus?
+A:        2 bits.
+-------------------------------------------------------------------------
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 10:44:16 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <40A1E83E.2000402@frodo.hserus.net>
+Date: Wed, 12 May 2004 14:32:54 +0530
+From: Shridhar Daithankar 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.6b) Gecko/20031205 Thunderbird/0.4
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Doug Y 
+Cc: psql-performance@postgresql.org
+Subject: Re: Clarification on some settings
+References: <6.0.1.1.2.20040511163104.01e9cbb0@mail.traderonline.com>
+In-Reply-To: <6.0.1.1.2.20040511163104.01e9cbb0@mail.traderonline.com>
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+ReSent-Date: Wed, 12 May 2004 10:43:55 -0300 (ADT)
+Resent-From: "Marc G. Fournier" 
+Resent-To: pgsql-performance@postgresql.org
+ReSent-Subject: Re: [PERFORM] Clarification on some settings
+ReSent-Message-ID: <20040512104354.A35531@ganymede.hub.org>
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/111
+X-Sequence-Number: 6942
+
+Doug Y wrote:
+
+> Hello,
+>   I've been having some performance issues with a DB I use. I'm trying 
+> to come up with some performance recommendations to send to the 
+> "adminstrator".
+> 
+> Hardware:
+> CPU0: Pentium III (Coppermine) 1000MHz (256k cache)
+> CPU1: Pentium III (Coppermine) 1000MHz (256k cache)
+> Memory: 3863468 kB (4 GB)
+> OS: Red Hat Linux release 7.2 (Enigma)
+> Kernel: 2.4.9-31smp
+> I/O I believe is a 3-disk raid 5.
+> 
+> /proc/sys/kernel/shmmax and /proc/sys/kernel/shmall were set to 2G
+> 
+> Postgres version: 7.3.4
+  > The DB schema is, well to put it nicely... not exactly normalized. No
+> constraints to speak of except for the requisite not-nulls on the 
+> primary keys (many of which are compound). Keys are mostly varchar(256) 
+> fields.
+> 
+> Ok for what I'm uncertain of...
+> shared_buffers:
+> According to http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+> Its more of a staging area and more isn't necessarily better. That psql 
+> relies on the OS to cache data for later use.
+> But according to 
+> http://www.ca.postgresql.org/docs/momjian/hw_performance/node3.html its 
+> where psql caches previous data for queries because the OS cache is 
+> slower, and should be as big as possible without causing swap.
+> Those seem to be conflicting statements. In our case, the 
+> "administrator" kept increasing this until performance seemed to 
+> increase, which means its now 250000 (x 8k is 2G).
+> Is this just a staging area for data waiting to move to the OS cache, or 
+> is this really the area that psql caches its data?
+
+It is the area where postgresql works. It updates data in this area and pushes 
+it to OS cache for disk writes later.
+
+By experience, larger does not mean better for this parameter. For multi-Gig RAM 
+machines, the best(on an average for wide variety of load) value found to be 
+around 10000-15000. May be even lower.
+
+It is a well known fact that raising this parameter unnecessarily decreases the 
+performance. You indicate that best performance occurred at 250000. This is very 
+very large compared to other people's experience.
+> 
+> effective_cache_size:
+> Again, according to the Varlena guide this tells psql how much system 
+> memory is available for it to do its work in.
+> until recently, this was set at the default value of 1000. It was just 
+> recently increased to 180000 (1.5G)
+> according to 
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html 
+> it should be about 25% of memory?
+
+No rule of thumb. It is amount of memory OS will dedicate to psotgresql data 
+buffers. Depending uponn what else you run on machine, it could be 
+straight-forward or noodly value to calculate. For a 4GB machine, 1.5GB is quite 
+good but coupled with 2G of shared buffers it could push the machines to swap 
+storm. And swapping shared buffers is a big performance hit.
+
+> 
+> Finally sort_mem:
+> Was until recently left at the default of 1000. Is now 16000.
+
+Sort memory is per sort not per query or per connection. So depending upon how 
+many concurrent connections you entertain, it could take quite a chuck of RAM.
+> 
+> Increasing the effective cache and sort mem didn't seem to make much of 
+> a difference. I'm guessing the eff cache was probably raised a bit too 
+> much, and shared_buffers is way to high.
+
+I agree. For shared buffers start with 5000 and increase in batches on 1000. Or 
+set it to a high value and check with ipcs for maximum shared memory usage. If 
+share memory usage peaks at 100MB, you don't need more than say 120MB of buffers.
+
+> 
+> What can I do to help determine what the proper settings should be 
+> and/or look at other possible choke points. What should I look for in 
+> iostat, mpstat, or vmstat as red flags that cpu, memory, or i/o bound?
+
+Yes. vmstat is usually a lot of help to locate the bottelneck.
+
+> DB maintenance wise, I don't believe they were running vacuum full until 
+> I told them a few months ago that regular vacuum analyze no longer 
+> cleans out dead tuples. Now normal vac is run daily, vac full weekly 
+> (supposedly). How can I tell from the output of vacuum if the vac fulls 
+> aren't being done, or not done often enough? Or from the system tables, 
+> what can I read?
+
+In 7.4 you can do vacuum full verbose and it will tell you the stats at the end. 
+For 7.3.x, its not there.
+
+I suggest you vacuum full database once.(For large database, dumping restoring 
+might work faster. Dump/restore and vacuum full both lock the database 
+exclusively i.e. downtime. So I guess faster the better for you. But there is no 
+tool/guideline to determine which way to go.)
+
+> Is there anywhere else I can look for possible clues? I have access to 
+> the DB super-user, but not the system root/user.
+
+Other than hardware tuning, find out slow/frequent queries. Use explain analyze 
+to determine why they are so slow. Forgetting to typecast a where clause and 
+using sequential scan could cost you lot more than mistuned postgresql 
+configuration.
+
+> Thank you for your time. Please let me know any help or suggestions you 
+> may have. Unfortunately upgrading postgres, OS, kernel, or re-writing 
+> schema is most likely not an option.
+
+I hope you can change your queries.
+
+HTH
+
+  Shridhar
+
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 07:15:15 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+From: Manfred Koizar 
+To: Paul Tuckfield 
+Cc: Bjoern Metzdorf ,
+	"Pgsql-Admin (E-mail)" ,
+	"scott.marlowe" , pgsql-performance@postgresql.org
+Subject: Re: [PERFORM] Quad processor options
+Date: Wed, 12 May 2004 12:17:27 +0200
+Message-ID: <5nt3a05l0q1ivc2179qsjqhpa141stu9ek@email.aon.at>
+References: 
+	<40A13A78.9000607@turtle-entertainment.de>
+	<089ED266-A39D-11D8-A34F-000393BD6C3E@tuckfield.com>
+In-Reply-To: <089ED266-A39D-11D8-A34F-000393BD6C3E@tuckfield.com>
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+
+On Tue, 11 May 2004 15:46:25 -0700, Paul Tuckfield 
+wrote:
+>- the "cache" column shows that linux is using 2.3G for cache. (way too 
+>much)
+
+There is no such thing as "way too much cache".
+
+>   you generally want to give memory to postgres to keep it "close" to 
+>the user,
+
+Yes, but only a moderate amount of memory.
+
+>   not leave it unused to be claimed by linux cache
+
+Cache is not unused memory.
+
+>- I'll bet you have a low value for shared buffers, like 10000.  On 
+>your 3G system
+>   you should ramp up the value to at least 1G (125000 8k buffers) 
+
+In most cases this is almost the worst thing you can do.  The only thing
+even worse would be setting it to 1.5 G.
+
+Postgres is just happy with a moderate shared_buffers setting.  We
+usually recommend something like 10000.  You could try 20000, but don't
+increase it beyond that without strong evidence that it helps in your
+particular case.
+
+This has been discussed several times here, on -hackers and on -general.
+Search the archives for more information.
+
+Servus
+ Manfred
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 07:23:14 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+Content-Transfer-Encoding: 7bit
+From: Halford Dace 
+Subject: Re: [PERFORM] Quad processor options
+Date: Wed, 12 May 2004 12:27:18 +0200
+To: pgsql-admin@postgresql.org
+X-Mailer: Apple Mail (2.613)
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+
+On 12 May 2004, at 12:17 PM, Manfred Koizar wrote:
+
+> On Tue, 11 May 2004 15:46:25 -0700, Paul Tuckfield 
+> wrote:
+>
+>> - I'll bet you have a low value for shared buffers, like 10000.  On
+>> your 3G system
+>>   you should ramp up the value to at least 1G (125000 8k buffers)
+>
+> In most cases this is almost the worst thing you can do.  The only 
+> thing
+> even worse would be setting it to 1.5 G.
+>
+> Postgres is just happy with a moderate shared_buffers setting.  We
+> usually recommend something like 10000.  You could try 20000, but don't
+> increase it beyond that without strong evidence that it helps in your
+> particular case.
+>
+> This has been discussed several times here, on -hackers and on 
+> -general.
+> Search the archives for more information.
+
+We have definitely found this to be true here.  We have some fairly 
+complex queries running on a rather underpowered box (beautiful but 
+steam-driven old Silicon Graphics Challenge DM).  We ended up using a 
+very slight increase to shared buffers, but gaining ENORMOUSLY through 
+proper optimisation of queries, appropriate indices and the use of 
+optimizer-bludgeons like "SET ENABLE_SEQSCAN = OFF"
+
+Hal
+
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 10:46:25 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+Date: Wed, 12 May 2004 07:44:37 -0600 (MDT)
+From: "scott.marlowe" 
+To: Grega Bremec 
+Cc: Bjoern Metzdorf ,
+	,
+	"Pgsql-Admin (E-mail)" 
+Subject: Re: [PERFORM] Quad processor options
+In-Reply-To: <20040512045832.GA10035@elbereth.noviforum.si>
+Message-ID: 
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+
+On Wed, 12 May 2004, Grega Bremec wrote:
+
+> ...and on Tue, May 11, 2004 at 03:02:24PM -0600, scott.marlowe used the keyboard:
+> > 
+> > If you get the LSI megaraid, make sure you're running the latest megaraid 
+> > 2 driver, not the older, slower 1.18 series.  If you are running linux, 
+> > look for the dkms packaged version.  dkms, (Dynamic Kernel Module System) 
+> > automagically compiles and installs source rpms for drivers when you 
+> > install them, and configures the machine to use them to boot up.  Most 
+> > drivers seem to be slowly headed that way in the linux universe, and I 
+> > really like the simplicity and power of dkms.
+> > 
+> 
+> Hi,
+> 
+> Given the fact LSI MegaRAID seems to be a popular solution around here, and
+> many of you folx use Linux as well, I thought sharing this piece of info
+> might be of use.
+> 
+> Running v2 megaraid driver on a 2.4 kernel is actually not a good idea _at_
+> _all_, as it will silently corrupt your data in the event of a disk failure.
+> 
+> Sorry to have to say so, but we tested it (on kernels up to 2.4.25, not sure
+> about 2.4.26 yet) and it comes out it doesn't do hotswap the way it should.
+> 
+> Somehow the replaced disk drives are not _really_ added to the array, which
+> continues to work in degraded mode for a while and (even worse than that)
+> then starts to think the replaced disk is in order without actually having
+> resynced it, thus beginning to issue writes to non-existant areas of it.
+> 
+> The 2.6 megaraid driver indeed seems to be a merged version of the above
+> driver and the old one, giving both improved performance and correct
+> functionality in the event of a hotswap taking place.
+
+This doesn't make any sense to me, since the hot swapping is handled by 
+the card autonomously.  I also tested it with a hot spare and pulled one 
+drive and it worked fine during our acceptance testing.
+
+However, I've got a hot spare machine I can test on, so I'll try it again 
+and see if I can make it fail.
+
+when testing it, was the problem present in certain RAID configurations or 
+only one type or what?  I'm curious to try and reproduce this problem, 
+since I've never heard of it before.
+
+Also, what firmware version were those megaraid cards, ours is fairly 
+new, as we got it at the beginning of this year, and I'm wondering if it 
+is a firmware issue.
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 15:58:24 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+To: pgsql-performance@postgresql.org
+Path: not-for-mail
+From: Vivek Khera 
+Newsgroups: ml.postgres.performance
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Wed, 12 May 2004 14:57:58 -0400
+Organization: Khera Communications, Inc., Rockville, MD
+Lines: 31
+Message-ID: 
+References: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+	<40A03435.7020300@geophile.com> <24638.1084245829@sss.pgh.pa.us>
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+
+>>>>> "TL" == Tom Lane  writes:
+
+TL> Jack Orenstein  writes:
+>> I'm looking at one case in which two successive transactions, each
+>> updating a handful of records, take 26 and 18 *seconds* (not msec) to
+>> complete. These transactions normally complete in under 30 msec.
+
+TL> I've seen installations in which it seemed that the "normal" query load
+TL> was close to saturating the available disk bandwidth, and the extra load
+TL> imposed by a background VACUUM just pushed the entire system's response
+TL> time over a cliff.  In an installation that has I/O capacity to spare,
+
+me stand up waving hand... ;-)  This is my only killer problem left.
+I always peg my disk usage at 100% when vacuum runs, and other queries
+are slow too.  When not running vacuum, my queries are incredibly
+zippy fast, including joins and counts and group by's on upwards of
+100k rows at a time.
+
+TL> I suspect that the same observations hold true for checkpoints, though
+TL> I haven't specifically seen an installation suffering from that effect.
+
+I don't see that.  But I also set checkpoint segments to about 50 on
+my big server.
+
+
+
+-- 
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
+Vivek Khera, Ph.D.                Khera Communications, Inc.
+Internet: khera@kciLink.com       Rockville, MD  +1-301-869-4449 x806
+AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 16:05:33 2004
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+From: Vivek Khera 
+Newsgroups: ml.postgres.performance
+Subject: Re: Configuring PostgreSQL to minimize impact of
+Date: Wed, 12 May 2004 15:05:05 -0400
+Organization: Khera Communications, Inc., Rockville, MD
+Lines: 18
+Message-ID: 
+References: 
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+
+>>>>> "JAR" == J Andrew Rogers  writes:
+
+
+JAR> The LSI MegaRAID reading/writing/caching behavior is user configurable.
+JAR> It will support both write-back and write-through, and IIRC, three
+JAR> different algorithms for reading (none, read-ahead, adaptive).  Plenty
+JAR> of configuration options.
+
+For PG max performance, you want to set it for write-back and
+read-ahead (adaptive has been claimed to be bad, but I got similar
+performace from read-ahead and adaptive, so YMMV).
+
+
+-- 
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
+Vivek Khera, Ph.D.                Khera Communications, Inc.
+Internet: khera@kciLink.com       Rockville, MD  +1-301-869-4449 x806
+AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 16:25:21 2004
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+Date: Wed, 12 May 2004 15:22:47 -0400
+From: jao@geophile.com
+To: Vivek Khera 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+References: <200405101909.i4AJ9Wv09415@candle.pha.pa.us>
+	<40A03435.7020300@geophile.com> <24638.1084245829@sss.pgh.pa.us>
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+
+Quoting Vivek Khera :
+
+> >>>>> "TL" == Tom Lane  writes:
+> 
+> TL> Jack Orenstein  writes:
+> >> I'm looking at one case in which two successive transactions, each
+> >> updating a handful of records, take 26 and 18 *seconds* (not msec) to
+> >> complete. These transactions normally complete in under 30 msec.
+> 
+> TL> I've seen installations in which it seemed that the "normal" query load
+> TL> was close to saturating the available disk bandwidth, and the extra load
+> TL> imposed by a background VACUUM just pushed the entire system's response
+> TL> time over a cliff.  In an installation that has I/O capacity to spare,
+> ...
+> TL> I suspect that the same observations hold true for checkpoints, though
+> TL> I haven't specifically seen an installation suffering from that effect.
+> 
+> I don't see that.  But I also set checkpoint segments to about 50 on
+> my big server.
+
+But wouldn't that affect checkpoint frequency, not checkpoint cost?
+
+Jack Orenstein
+
+
+----------------------------------------------------------------
+This message was sent using IMP, the Internet Messaging Program.
+
+From pgsql-performance-owner@postgresql.org  Wed May 12 16:29:33 2004
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+	<40A03435.7020300@geophile.com> <24638.1084245829@sss.pgh.pa.us>
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+Content-Type: text/plain; charset=US-ASCII; format=flowed
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+Content-Transfer-Encoding: 7bit
+From: Vivek Khera 
+Subject: Re: Configuring PostgreSQL to minimize impact of checkpoints
+Date: Wed, 12 May 2004 15:29:11 -0400
+To: pgsql-performance@postgresql.org
+X-Mailer: Apple Mail (2.613)
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+
+
+On May 12, 2004, at 3:22 PM, jao@geophile.com wrote:
+
+>>
+>> I don't see that.  But I also set checkpoint segments to about 50 on
+>> my big server.
+>
+> But wouldn't that affect checkpoint frequency, not checkpoint cost
+
+Seems reasonable.  I suppose checkpointing doesn't cost as much disk 
+I/O as vacuum does.  My checkpoints are also on a separate RAID volume 
+on a separate RAID channel, so perhaps that gives me extra bandwidth to 
+perform the checkpoints.
+
+
+
+From pgsql-admin-owner@postgresql.org  Wed May 12 19:41:24 2004
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+Date: Thu, 13 May 2004 00:40:58 +0200
+From: Bjoern Metzdorf 
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+To: pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Quad processor options - summary
+References: 
+In-Reply-To: 
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+
+Hi,
+
+at first, many thanks for your valuable replies. On my quest for the 
+ultimate hardware platform I'll try to summarize the things I learned.
+
+-------------------------------------------------------------
+
+This is our current setup:
+
+Hardware:
+Dual Xeon DP 2.4 on a TYAN S2722-533 with HT enabled
+3 GB Ram (2 x 1 GB + 2 x 512 MB)
+Mylex Extremeraid Controller U160 running RAID 10 with 4 x 18 GB SCSI 
+10K RPM, no other drives involved (system, pgdata and wal are all on the 
+same volume).
+
+Software:
+Debian 3.0 Woody
+Postgresql 7.4.1 (selfcompiled, no special optimizations)
+Kernel 2.4.22 + fixes
+
+Database specs:
+Size of a gzipped -9 full dump is roughly 1 gb
+70-80% selects, 20-30% updates (roughly estimated)
+up to 700-800 connections during peak times
+kernel.shmall = 805306368
+kernel.shmmax = 805306368
+max_connections = 900
+shared_buffers = 20000
+sort_mem = 16384
+checkpoint_segments = 6
+statistics collector is enabled (for pg_autovacuum)
+
+Loads:
+We are experiencing average CPU loads of up to 70% during peak hours. As 
+Paul Tuckfield correctly pointed out, my vmstat output didn't support 
+this. This output was not taken during peak times, it was freshly 
+grabbed when I wrote my initial mail. It resembles perhaps 50-60% peak 
+time load (30% cpu usage). iostat does not give results about disk 
+usage, I don't know exactly why, the blk_read/wrtn columns are just 
+empty. (Perhaps due to the Mylex rd driver, I don't know).
+
+-------------------------------------------------------------
+
+Suggestions and solutions given:
+
+Anjan Dave reported, that he is pretty confident with his Quad Xeon 
+setups, which will cost less than $20K at Dell with a reasonable 
+hardware setup. ( Dell 6650 with 2.0GHz/1MB cache/8GB Memory, 5 internal 
+drives (4 in RAID 10, 1 spare) on U320, 128MB cache on the PERC controller)
+
+Scott Marlowe pointed out, that one should consider more than 4 drives 
+(6 to 8, 10K rpm is enough, 15K is rip-off) for a Raid 10 setup, because 
+that can boost performance quite a lot. One should also be using a 
+battery backed raid controller. Scott has good experiences with the LSI 
+Megaraid single channel controller, which is reasonably priced at ~ 
+$500. He also stated, that 20-30% writes on a database is quite a lot.
+
+Next Rob Sell told us about his research on more-than-2-way Intel based 
+systems. The memory bandwidth on the xeon platform is always shared 
+between the cpus. While a 2way xeon may perform quite well, a 4way 
+system will be suffering due to the reduced memory bandwith available 
+for each processor.
+
+J. Andrew Roberts supports this. He said that 4way opteron systems scale 
+much better than a 4way xeon system. Scaling limits begin at 6-8 cpus on 
+the opteron platform. He also says that a fully equipped dual channel 
+LSI Megaraid 320 with 256MB cache ram will be less that $1K. A complete 
+4way opteron system will be at $10K-$12K.
+
+Paul Tuckfield then gave the suggestion to bump up my shared_buffers. 
+With a 3GB memory system, I could happily be using 1GB for shared 
+buffers (125000). This was questioned by Andrew McMillian, Manfred 
+Kolzar and Halford Dace, who say that common tuning advices limit 
+reasonable settings to 10000-20000 shared buffers, because the OS is 
+better at caching than the database.
+
+-------------------------------------------------------------
+
+Conclusion:
+
+After having read some comparisons between n-way xeon and opteron systems:
+
+http://www.anandtech.com/IT/showdoc.html?i=1982
+http://www.aceshardware.com/read.jsp?id=60000275
+
+I was given the impression, that an opteron system is the way to go.
+
+This is what I am considering the ultimate platform for postgresql:
+
+Hardware:
+Tyan Thunder K8QS board
+2-4 x Opteron 848 in NUMA mode
+4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+channels (3 + 4) for pgdata including indexes and wal.
+2 x 80 GB S-ATA IDE for system, running linux software raid 1 or 
+available onboard hardware raid (perhaps also 2 x 36 GB SCSI)
+
+Software:
+Debian Woody in amd64 biarch mode, or perhaps Redhat/SuSE Enterprise 
+64bit distributions.
+Kernel 2.6
+Postgres 7.4.2 in 64bit mode
+shared_buffers = 20000
+a bumbed up effective_cache_size
+
+Now the only problem left (besides my budget) is the availability of 
+such a system.
+
+I have found some vendors which ship similar systems, so I will have to 
+talk to them about my dream configuration. I will not self build this 
+system, there are too many obstacles.
+
+I expect this system to come out on about 12-15K Euro. Very optimistic, 
+I know :)
+
+These are the vendors I found up to now:
+
+http://www.appro.com/product/server_4144h.asp
+http://www.appro.com/product/server_4145h.asp
+http://www.pyramid.de/d/builttosuit/server/4opteron.shtml
+http://www.rainbow-it.co.uk/productslist.aspx?CategoryID=4&selection=2
+http://www.quadopteron.com/
+
+They all seem to sell more or less the same system. I found also some 
+other vendors which built systems on celestica or amd boards, but they 
+are way too expensive.
+
+Buying such a machine is worth some good thoughts. If budget is a limit 
+and such a machine might not be maxed out during the next few months, it 
+would make more sense to go for a slightly slower system and an upgrade 
+when more power is needed.
+
+Thanks again for all your replies. I hope to have given a somehow clear 
+summary.
+
+Regards,
+Bjoern
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 10:02:39 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Subject: Re: Clarification on some settings
+From: Neil Conway 
+To: Shridhar Daithankar 
+Cc: Doug Y , psql-performance@postgresql.org
+In-Reply-To: <40A1E83E.2000402@frodo.hserus.net>
+References: <6.0.1.1.2.20040511163104.01e9cbb0@mail.traderonline.com>
+	<40A1E83E.2000402@frodo.hserus.net>
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+Resent-From: "Marc G. Fournier" 
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+ReSent-Subject: Re: [PERFORM] Clarification on some settings
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+
+On Wed, 2004-05-12 at 05:02, Shridhar Daithankar wrote:
+> I agree. For shared buffers start with 5000 and increase in batches on 1000. Or 
+> set it to a high value and check with ipcs for maximum shared memory usage. If 
+> share memory usage peaks at 100MB, you don't need more than say 120MB of buffers.
+
+If your DB touches more than 100MB worth of buffers over time, shared
+memory consumption won't peak at 100MB. PG shared buffers are only
+"recycled" when there are no unused buffers available, so this isn't a
+really valid way to determine the right shared_buffers setting.
+
+-Neil
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 10:57:17 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Thu, 13 May 2004 19:31:29 +1200
+From: Mark Kirkwood 
+Subject: Re: Clarification on some settings
+In-reply-to: <40A1E83E.2000402@frodo.hserus.net>
+To: Shridhar Daithankar 
+Cc: Doug Y , psql-performance@postgresql.org
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+X-Sequence-Number: 6954
+
+Note that effective_cache_size is merely a hint to that planner to say 
+"I have this much os buffer cache to use" - it is not actually allocated.
+
+It is shared_buffers that will hurt you if it is too high (10000 - 25000 
+is the usual sweet spot).
+
+best wishes
+
+Mark
+
+
+Shridhar Daithankar wrote:
+
+>
+>>
+>> Increasing the effective cache and sort mem didn't seem to make much 
+>> of a difference. I'm guessing the eff cache was probably raised a bit 
+>> too much, and shared_buffers is way to high.
+>
+>
+> I agree. For shared buffers start with 5000 and increase in batches on 
+> 1000. Or set it to a high value and check with ipcs for maximum shared 
+> memory usage. If share memory usage peaks at 100MB, you don't need 
+> more than say 120MB of buffers.
+>
+>
+>
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 09:33:18 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for pgsql-performance@postgresql.org; Thu, 13 May 2004 14:39:52 +0200
+From: "Fabio Panizzutti" 
+To: 
+Subject: Query plan on identical tables differs . Why ?
+Date: Thu, 13 May 2004 14:42:51 +0200
+Message-ID: <005c01c438e7$ced25c30$3c02020a@ufficio>
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+
+Hello I'm tuning a postgresql (7.4.2) server for best performance .
+I have a question about the planner .
+I have two identical tables : one stores short data (about 2.000.000
+record now) and
+the other historycal data ( about 8.000.000 record now and growing ...) 
+
+ 
+A simple test query :   select tag_id,valore_tag,data_tag from
+storico_misure where (data_tag>'2004-05-03' and data_tag <'2004-05-12')
+and tag_id=37423 ;
+
+Takes 57,637 ms on the short table and 1321,448 ms (!!) on the
+historycal table .Tables are vacuumed and reindexed .  
+
+
+
+Tables and query plans :
+
+\d storico_misure
+                   Table "tenore.storico_misure"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "pk_storico_misure_2" primary key, btree (data_tag, tag_id)
+    "pk_anagtstorico_misuree_idx_2" btree (tag_id)
+    "storico_misure_data_tag_idx_2" btree (data_tag)
+
+storico=# \d storico_misure_short
+                Table "tenore.storico_misure_short"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "storico_misure_short_pkey_2" primary key, btree (data_tag, tag_id)
+    "pk_anagtstorico_misuree_short_idx_2" btree (tag_id)
+    "storico_misure_short_data_tag_idx_2" btree (data_tag)
+
+storico=#
+storico=#
+storico=# explain select tag_id,valore_tag,data_tag from storico_misure
+where (data_tag>'2004-05-03' and data_tag <'2004-05-12') and
+tag_id=37423 ;
+ 
+QUERY PLAN
+
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+--------------------------
+ Index Scan using pk_storico_misure_2 on storico_misure
+(cost=0.00..1984.64 rows=658 width=21)
+   Index Cond: ((data_tag > '2004-05-03 00:00:00'::timestamp without
+time zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without time
+zone) AND (tag_id = 37423))
+(2 rows)
+
+Time: 1,667 ms
+storico=# explain select tag_id,valore_tag,data_tag from
+storico_misure_short where (data_tag>'2004-05-03' and data_tag
+<'2004-05-12') and tag_id=37423 ;
+                                                                   QUERY
+PLAN
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+-
+ Index Scan using pk_anagtstorico_misuree_short_idx_2 on
+storico_misure_short  (cost=0.00..1784.04 rows=629 width=20)
+   Index Cond: (tag_id = 37423)
+   Filter: ((data_tag > '2004-05-03 00:00:00'::timestamp without time
+zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without time
+zone))
+
+
+How can i force the planner to use the same query plan ? I'd like to
+test if using the same query plan i've better performace .
+
+Thanks in advance
+
+
+
+
+this is my posgresql.conf
+
+#-----------------------------------------------------------------------
+----
+# CONNECTIONS AND AUTHENTICATION
+#-----------------------------------------------------------------------
+----
+
+# - Connection Settings -
+
+tcpip_socket = true
+max_connections = 100
+	# note: increasing max_connections costs about 500 bytes of
+shared
+	# memory per connection slot, in addition to costs from
+shared_buffers
+        # and max_locks_per_transaction.
+#superuser_reserved_connections = 2
+port = 5432
+#unix_socket_directory = ''
+#unix_socket_group = ''
+#unix_socket_permissions = 0777	# octal
+#virtual_host = ''		# what interface to listen on; defaults
+to any
+#rendezvous_name = ''		# defaults to the computer name
+
+# - Security & Authentication -
+
+#authentication_timeout = 60	# 1-600, in seconds
+#ssl = false
+#password_encryption = true
+#krb_server_keyfile = ''
+#db_user_namespace = false
+
+
+#-----------------------------------------------------------------------
+----
+# RESOURCE USAGE (except WAL)
+#-----------------------------------------------------------------------
+----
+
+# - Memory -
+
+shared_buffers = 3000		# min 16, at least max_connections*2,
+8KB each
+sort_mem = 4096 		# min 64, size in KB
+vacuum_mem = 32768		# min 1024, size in KB
+
+# - Free Space Map -
+
+#max_fsm_pages = 20000		# min max_fsm_relations*16, 6 bytes each
+#max_fsm_relations = 1000	# min 100, ~50 bytes each
+
+# - Kernel Resource Usage -
+
+#max_files_per_process = 1000	# min 25
+#preload_libraries = ''
+
+
+#-----------------------------------------------------------------------
+----
+# WRITE AHEAD LOG
+#-----------------------------------------------------------------------
+----
+
+# - Settings -
+
+fsync = false			# turns forced synchronization on or off
+#wal_sync_method = fsync	# the default varies across platforms:
+				# fsync, fdatasync, open_sync, or
+open_datasync
+#wal_buffers = 8		# min 4, 8KB each
+
+# - Checkpoints -
+
+checkpoint_segments = 12	# in logfile segments, min 1, 16MB each
+#checkpoint_timeout = 300	# range 30-3600, in seconds
+#checkpoint_warning = 30	# 0 is off, in seconds
+#commit_delay = 0		# range 0-100000, in microseconds
+#commit_siblings = 5		# range 1-1000
+
+
+#-----------------------------------------------------------------------
+----
+# QUERY TUNING
+#-----------------------------------------------------------------------
+----
+
+# - Planner Method Enabling -
+
+enable_hashagg = false
+enable_hashjoin = false
+enable_indexscan = true
+enable_mergejoin = true
+enable_nestloop = false
+enable_seqscan = true
+enable_sort = false
+enable_tidscan = false
+
+# - Planner Cost Constants -
+
+#effective_cache_size = 1000	# typically 8KB each
+#random_page_cost = 4		# units are one sequential page fetch
+cost
+#cpu_tuple_cost = 0.01		# (same)
+#cpu_index_tuple_cost = 0.001	# (same)
+#cpu_operator_cost = 0.0025	# (same)
+
+# - Genetic Query Optimizer -
+
+#geqo = true
+#geqo_threshold = 11
+#geqo_effort = 1
+#geqo_generations = 0
+#geqo_pool_size = 0		# default based on tables in statement,
+				# range 128-1024
+#geqo_selection_bias = 2.0	# range 1.5-2.0
+
+# - Other Planner Options -
+
+#default_statistics_target = 10	# range 1-1000
+#from_collapse_limit = 8
+#join_collapse_limit = 8	# 1 disables collapsing of explicit
+JOINs
+
+
+#-----------------------------------------------------------------------
+----
+# ERROR REPORTING AND LOGGING
+#-----------------------------------------------------------------------
+----
+
+# - Syslog -
+
+#syslog = 0			# range 0-2; 0=stdout; 1=both; 2=syslog
+#syslog_facility = 'LOCAL0'
+#syslog_ident = 'postgres'
+
+# - When to Log -
+
+#client_min_messages = notice	# Values, in order of decreasing detail:
+				#   debug5, debug4, debug3, debug2,
+debug1,
+				#   log, info, notice, warning, error
+
+#log_min_messages = notice	# Values, in order of decreasing detail:
+				#   debug5, debug4, debug3, debug2,
+debug1,
+				#   info, notice, warning, error, log,
+fatal,
+				#   panic
+
+#log_error_verbosity = default   # terse, default, or verbose messages
+
+#log_min_error_statement = panic # Values in order of increasing
+severity:
+				 #   debug5, debug4, debug3, debug2,
+debug1,
+				 #   info, notice, warning, error,
+panic(off)
+				 
+#log_min_duration_statement = -1 # Log all statements whose
+				 # execution time exceeds the value, in
+				 # milliseconds.  Zero prints all
+queries.
+				 # Minus-one disables.
+
+#silent_mode = false		 # DO NOT USE without Syslog!
+
+# - What to Log -
+
+#debug_print_parse = false
+#debug_print_rewritten = false
+#debug_print_plan = false
+#debug_pretty_print = false
+#log_connections = false
+#log_duration = false
+#log_pid = false
+#log_statement = false
+#log_timestamp = false
+#log_hostname = false
+#log_source_port = false
+
+
+#-----------------------------------------------------------------------
+----
+# RUNTIME STATISTICS
+#-----------------------------------------------------------------------
+----
+
+# - Statistics Monitoring -
+
+#log_parser_stats = false
+#log_planner_stats = false
+#log_executor_stats = false
+#log_statement_stats = false
+
+# - Query/Index Statistics Collector -
+
+stats_start_collector = true
+stats_command_string = true
+#stats_block_level = false
+stats_row_level = true
+#stats_reset_on_server_start = true
+
+
+#-----------------------------------------------------------------------
+----
+# CLIENT CONNECTION DEFAULTS
+#-----------------------------------------------------------------------
+----
+
+# - Statement Behavior -
+
+#search_path = '$user,public'	# schema names
+#check_function_bodies = true
+#default_transaction_isolation = 'read committed'
+#default_transaction_read_only = false
+statement_timeout = 360000		# 0 is disabled, in milliseconds
+
+# - Locale and Formatting -
+
+#datestyle = 'iso, mdy'
+#timezone = unknown		# actually, defaults to TZ environment
+setting
+#australian_timezones = false
+#extra_float_digits = 0		# min -15, max 2
+#client_encoding = sql_ascii	# actually, defaults to database
+encoding
+
+# These settings are initialized by initdb -- they may be changed
+lc_messages = 'it_IT.UTF-8'		# locale for system error
+message strings
+lc_monetary = 'it_IT.UTF-8'		# locale for monetary formatting
+lc_numeric = 'it_IT.UTF-8'		# locale for number formatting
+lc_time = 'it_IT.UTF-8'			# locale for time formatting
+
+# - Other Defaults -
+
+#explain_pretty_print = true
+#dynamic_library_path = '$libdir'
+#max_expr_depth = 10000		# min 10
+
+
+#-----------------------------------------------------------------------
+----
+# LOCK MANAGEMENT
+#-----------------------------------------------------------------------
+----
+
+#deadlock_timeout = 1000	# in milliseconds
+#max_locks_per_transaction = 64	# min 10, ~260*max_connections bytes
+each
+
+
+#-----------------------------------------------------------------------
+----
+# VERSION/PLATFORM COMPATIBILITY
+#-----------------------------------------------------------------------
+----
+
+# - Previous Postgres Versions -
+
+#add_missing_from = true
+#regex_flavor = advanced	# advanced, extended, or basic
+#sql_inheritance = true
+
+# - Other Platforms & Clients -
+
+#transform_null_equals = false
+
+
+
+
+
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 10:05:54 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 13 May 2004 18:35:25 +0530
+Message-ID: <40A3728F.2030402@frodo.hserus.net>
+Date: Thu, 13 May 2004 18:35:19 +0530
+From: Shridhar Daithankar 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.6b) Gecko/20031205 Thunderbird/0.4
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Fabio Panizzutti 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Query plan on identical tables differs . Why ?
+References: <005c01c438e7$ced25c30$3c02020a@ufficio>
+In-Reply-To: <005c01c438e7$ced25c30$3c02020a@ufficio>
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Spam-Level: 
+X-Archive-Number: 200405/120
+X-Sequence-Number: 6951
+
+Fabio Panizzutti wrote:
+> storico=# explain select tag_id,valore_tag,data_tag from storico_misure
+> where (data_tag>'2004-05-03' and data_tag <'2004-05-12') and
+> tag_id=37423 ;
+
+Can you please post explain analyze? That includes actual timings.
+
+Looking at the schema, can you try "and tag_id=37423::integer" instead?
+
+> enable_hashagg = false
+> enable_hashjoin = false
+> enable_indexscan = true
+> enable_mergejoin = true
+> enable_nestloop = false
+> enable_seqscan = true
+> enable_sort = false
+> enable_tidscan = false
+
+Why do you have these off? AFAIK, 7.4 improved hash aggregates a lot. So you 
+might miss on these in this case.
+
+> # - Planner Cost Constants -
+> 
+> #effective_cache_size = 1000	# typically 8KB each
+
+You might set it to something realistic.
+
+And what is your hardware setup? Disks/CPU/RAM?
+
+Just to be sure, you went thr.
+http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html and 
+http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html?
+
+HTH
+
+  Regards
+    Shridhar
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 10:15:54 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A374E8.5040809@cranel.com>
+Date: Thu, 13 May 2004 09:15:20 -0400
+From: Greg Spiegelberg 
+Organization: Cranel, Inc.
+User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040113
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Off Topic - Re: [PERFORM] Quad processor options - summary
+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+In-Reply-To: <40A2A7FA.6060403@turtle-entertainment.de>
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Spam-Level: 
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+X-Sequence-Number: 13439
+
+This is somthing I wish more of us did on the lists.  The list archives
+have solutions and workarounds for every variety of problem but very few
+summary emails exist.  A good example of this practice is in the
+sun-managers mailling list.  The original poster sends a "SUMMARY" reply
+to the list with the original problem included and all solutions found.
+Also makes searching the list archives easier.
+
+Simply a suggestion for us all including myself.
+
+Greg
+
+
+Bjoern Metzdorf wrote:
+> Hi,
+> 
+> at first, many thanks for your valuable replies. On my quest for the 
+> ultimate hardware platform I'll try to summarize the things I learned.
+> 
+> -------------------------------------------------------------
+> 
+> This is our current setup:
+> 
+> Hardware:
+> Dual Xeon DP 2.4 on a TYAN S2722-533 with HT enabled
+> 3 GB Ram (2 x 1 GB + 2 x 512 MB)
+> Mylex Extremeraid Controller U160 running RAID 10 with 4 x 18 GB SCSI 
+> 10K RPM, no other drives involved (system, pgdata and wal are all on the 
+> same volume).
+> 
+> Software:
+> Debian 3.0 Woody
+> Postgresql 7.4.1 (selfcompiled, no special optimizations)
+> Kernel 2.4.22 + fixes
+> 
+> Database specs:
+> Size of a gzipped -9 full dump is roughly 1 gb
+> 70-80% selects, 20-30% updates (roughly estimated)
+> up to 700-800 connections during peak times
+> kernel.shmall = 805306368
+> kernel.shmmax = 805306368
+> max_connections = 900
+> shared_buffers = 20000
+> sort_mem = 16384
+> checkpoint_segments = 6
+> statistics collector is enabled (for pg_autovacuum)
+> 
+> Loads:
+> We are experiencing average CPU loads of up to 70% during peak hours. As 
+> Paul Tuckfield correctly pointed out, my vmstat output didn't support 
+> this. This output was not taken during peak times, it was freshly 
+> grabbed when I wrote my initial mail. It resembles perhaps 50-60% peak 
+> time load (30% cpu usage). iostat does not give results about disk 
+> usage, I don't know exactly why, the blk_read/wrtn columns are just 
+> empty. (Perhaps due to the Mylex rd driver, I don't know).
+> 
+> -------------------------------------------------------------
+> 
+> Suggestions and solutions given:
+> 
+> Anjan Dave reported, that he is pretty confident with his Quad Xeon 
+> setups, which will cost less than $20K at Dell with a reasonable 
+> hardware setup. ( Dell 6650 with 2.0GHz/1MB cache/8GB Memory, 5 internal 
+> drives (4 in RAID 10, 1 spare) on U320, 128MB cache on the PERC controller)
+> 
+> Scott Marlowe pointed out, that one should consider more than 4 drives 
+> (6 to 8, 10K rpm is enough, 15K is rip-off) for a Raid 10 setup, because 
+> that can boost performance quite a lot. One should also be using a 
+> battery backed raid controller. Scott has good experiences with the LSI 
+> Megaraid single channel controller, which is reasonably priced at ~ 
+> $500. He also stated, that 20-30% writes on a database is quite a lot.
+> 
+> Next Rob Sell told us about his research on more-than-2-way Intel based 
+> systems. The memory bandwidth on the xeon platform is always shared 
+> between the cpus. While a 2way xeon may perform quite well, a 4way 
+> system will be suffering due to the reduced memory bandwith available 
+> for each processor.
+> 
+> J. Andrew Roberts supports this. He said that 4way opteron systems scale 
+> much better than a 4way xeon system. Scaling limits begin at 6-8 cpus on 
+> the opteron platform. He also says that a fully equipped dual channel 
+> LSI Megaraid 320 with 256MB cache ram will be less that $1K. A complete 
+> 4way opteron system will be at $10K-$12K.
+> 
+> Paul Tuckfield then gave the suggestion to bump up my shared_buffers. 
+> With a 3GB memory system, I could happily be using 1GB for shared 
+> buffers (125000). This was questioned by Andrew McMillian, Manfred 
+> Kolzar and Halford Dace, who say that common tuning advices limit 
+> reasonable settings to 10000-20000 shared buffers, because the OS is 
+> better at caching than the database.
+> 
+> -------------------------------------------------------------
+> 
+> Conclusion:
+> 
+> After having read some comparisons between n-way xeon and opteron systems:
+> 
+> http://www.anandtech.com/IT/showdoc.html?i=1982
+> http://www.aceshardware.com/read.jsp?id=60000275
+> 
+> I was given the impression, that an opteron system is the way to go.
+> 
+> This is what I am considering the ultimate platform for postgresql:
+> 
+> Hardware:
+> Tyan Thunder K8QS board
+> 2-4 x Opteron 848 in NUMA mode
+> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+> channels (3 + 4) for pgdata including indexes and wal.
+> 2 x 80 GB S-ATA IDE for system, running linux software raid 1 or 
+> available onboard hardware raid (perhaps also 2 x 36 GB SCSI)
+> 
+> Software:
+> Debian Woody in amd64 biarch mode, or perhaps Redhat/SuSE Enterprise 
+> 64bit distributions.
+> Kernel 2.6
+> Postgres 7.4.2 in 64bit mode
+> shared_buffers = 20000
+> a bumbed up effective_cache_size
+> 
+> Now the only problem left (besides my budget) is the availability of 
+> such a system.
+> 
+> I have found some vendors which ship similar systems, so I will have to 
+> talk to them about my dream configuration. I will not self build this 
+> system, there are too many obstacles.
+> 
+> I expect this system to come out on about 12-15K Euro. Very optimistic, 
+> I know :)
+> 
+> These are the vendors I found up to now:
+> 
+> http://www.appro.com/product/server_4144h.asp
+> http://www.appro.com/product/server_4145h.asp
+> http://www.pyramid.de/d/builttosuit/server/4opteron.shtml
+> http://www.rainbow-it.co.uk/productslist.aspx?CategoryID=4&selection=2
+> http://www.quadopteron.com/
+> 
+> They all seem to sell more or less the same system. I found also some 
+> other vendors which built systems on celestica or amd boards, but they 
+> are way too expensive.
+> 
+> Buying such a machine is worth some good thoughts. If budget is a limit 
+> and such a machine might not be maxed out during the next few months, it 
+> would make more sense to go for a slightly slower system and an upgrade 
+> when more power is needed.
+> 
+> Thanks again for all your replies. I hope to have given a somehow clear 
+> summary.
+> 
+> Regards,
+> Bjoern
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 5: Have you checked our extensive FAQ?
+> 
+>               http://www.postgresql.org/docs/faqs/FAQ.html
+
+
+-- 
+Greg Spiegelberg
+  Product Development Manager
+  Cranel, Incorporated.
+  Phone: 614.318.4314
+  Fax:   614.431.8388
+  Email: gspiegelberg@cranel.com
+Technology. Integrity. Focus. V-Solve!
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 10:56:30 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	id 1BOGnd-00053J-00; Thu, 13 May 2004 16:03:01 +0200
+From: "Fabio Panizzutti" 
+To: "'Shridhar Daithankar'" 
+Cc: 
+Subject: R: Query plan on identical tables differs . Why ?
+Date: Thu, 13 May 2004 16:06:01 +0200
+Message-ID: <006301c438f3$6ca33460$3c02020a@ufficio>
+MIME-Version: 1.0
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+
+
+
+>>>-----Messaggio originale-----
+>>>Da: pgsql-performance-owner@postgresql.org=20
+>>>[mailto:pgsql-performance-owner@postgresql.org] Per conto di=20
+>>>Shridhar Daithankar
+>>>Inviato: gioved=EC 13 maggio 2004 15.05
+>>>A: Fabio Panizzutti
+>>>Cc: pgsql-performance@postgresql.org
+>>>Oggetto: Re: [PERFORM] Query plan on identical tables differs . Why ?
+>>>
+>>>
+>>>Fabio Panizzutti wrote:
+>>>> storico=3D# explain select tag_id,valore_tag,data_tag from=20
+>>>> storico_misure where (data_tag>'2004-05-03' and data_tag=20
+>>>> <'2004-05-12') and tag_id=3D37423 ;
+>>>
+>>>Can you please post explain analyze? That includes actual timings.
+
+storico=3D# explain analyze select tag_id,valore_tag,data_tag from
+storico_misure where (data_tag>'2004-05-03' and data_tag <'2004-05-12')
+and tag_id=3D37423 ;
+=20
+QUERY PLAN
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+--------------------------
+ Index Scan using pk_storico_misure_2 on storico_misure
+(cost=3D0.00..1984.64 rows=3D658 width=3D21) (actual time=3D723.441..1858.1=
+07
+rows=3D835 loops=3D1)
+   Index Cond: ((data_tag > '2004-05-03 00:00:00'::timestamp without
+time zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without time
+zone) AND (tag_id =3D 37423))
+ Total runtime: 1860.641 ms
+(3 rows)
+
+storico=3D# explain analyze select tag_id,valore_tag,data_tag from
+storico_misure_short where (data_tag>'2004-05-03' and data_tag
+<'2004-05-12') and tag_id=3D37423 ;
+=20
+QUERY PLAN
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+-------------------
+ Index Scan using pk_anagtstorico_misuree_short_idx_2 on
+storico_misure_short  (cost=3D0.00..1783.04 rows=3D629 width=3D20) (actual
+time=3D0.323..42.186 rows=3D864 loops=3D1)
+   Index Cond: (tag_id =3D 37423)
+   Filter: ((data_tag > '2004-05-03 00:00:00'::timestamp without time
+zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without time
+zone))
+ Total runtime: 43.166 ms
+
+
+
+
+>>>Looking at the schema, can you try "and=20
+>>>tag_id=3D37423::integer" instead?
+>>>
+
+I try :=20
+explain analyze select tag_id,valore_tag,data_tag from storico_misure
+where (data_tag>'2004-05-03' and data_tag <'2004-05-12') and
+tag_id=3D37423::integer;
+Index Scan using pk_storico_misure_2 on storico_misure
+(cost=3D0.00..1984.64 rows=3D658 width=3D21) (actual time=3D393.337..1303.9=
+98
+rows=3D835 loops=3D1)
+   Index Cond: ((data_tag > '2004-05-03 00:00:00'::timestamp without
+time zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without time
+zone) AND (tag_id =3D 37423))
+ Total runtime: 1306.484 ms
+
+>>>> enable_hashagg =3D false
+>>>> enable_hashjoin =3D false
+>>>> enable_indexscan =3D true
+>>>> enable_mergejoin =3D true
+>>>> enable_nestloop =3D false
+>>>> enable_seqscan =3D true
+>>>> enable_sort =3D false
+>>>> enable_tidscan =3D false
+>>>Why do you have these off? AFAIK, 7.4 improved hash=20
+>>>aggregates a lot. So you=20
+>>>might miss on these in this case.
+
+I try for debug purpose , now i reset all 'enable' to default :
+=20
+select * from pg_settings where name like 'enable%';
+       name       | setting | context | vartype |       source       |
+min_val | max_val
+------------------+---------+---------+---------+--------------------+--
+-------+---------
+ enable_hashagg   | on      | user    | bool    | configuration file |
+|
+ enable_hashjoin  | on      | user    | bool    | configuration file |
+|
+ enable_indexscan | on      | user    | bool    | configuration file |
+|
+ enable_mergejoin | on      | user    | bool    | configuration file |
+|
+ enable_nestloop  | on      | user    | bool    | configuration file |
+|
+ enable_seqscan   | on      | user    | bool    | configuration file |
+|
+ enable_sort      | on      | user    | bool    | configuration file |
+|
+ enable_tidscan   | on      | user    | bool    | configuration file |
+|
+(8 rows)
+
+The query plan are the same ....
+
+>>>> # - Planner Cost Constants -
+>>>>=20
+>>>> #effective_cache_size =3D 1000	# typically 8KB each
+>>>
+>>>You might set it to something realistic.
+>>>
+
+I try 10000 and 100000 but nothing change .
+
+
+
+>>>And what is your hardware setup? Disks/CPU/RAM?
+
+32GB SCSI/DUAL Intel(R) Pentium(R) III CPU family      1133MHz/  1GB RAM
+and linux red-hat 9
+
+
+I don't understand why the planner chose a different query plan on
+identical tables with same indexes .=20
+
+Thanks a lot for help!.
+
+Fabio
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 12:01:36 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+To: "Fabio Panizzutti" 
+Cc: "'Shridhar Daithankar'" ,
+	pgsql-performance@postgresql.org
+Subject: Re: R: Query plan on identical tables differs . Why ? 
+In-reply-to: <006301c438f3$6ca33460$3c02020a@ufficio> 
+References: <006301c438f3$6ca33460$3c02020a@ufficio>
+Comments: In-reply-to "Fabio Panizzutti" 
+	message dated "Thu, 13 May 2004 16:06:01 +0200"
+Date: Thu, 13 May 2004 11:01:00 -0400
+Message-ID: <8904.1084460460@sss.pgh.pa.us>
+From: Tom Lane 
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+
+"Fabio Panizzutti"  writes:
+> I don't understand why the planner chose a different query plan on
+> identical tables with same indexes . 
+
+Different data statistics; not to mention different table sizes
+(the cost equations are not linear).
+
+Have you ANALYZEd (or VACUUM ANALYZEd) both tables recently?
+
+If the stats are up to date but still not doing the right thing,
+you might try increasing the statistics target for the larger
+table's tag_id column.  See ALTER TABLE SET STATISTICS.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 12:16:58 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Thu, 13 May 2004 08:16:34 -0700 (PDT)
+From: Stephan Szabo 
+To: Fabio Panizzutti 
+Cc: 'Shridhar Daithankar' ,
+	pgsql-performance@postgresql.org
+Subject: Re: R: Query plan on identical tables differs . Why ?
+In-Reply-To: <006301c438f3$6ca33460$3c02020a@ufficio>
+Message-ID: <20040513080130.E3465@megazone.bigpanda.com>
+References: <006301c438f3$6ca33460$3c02020a@ufficio>
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+
+On Thu, 13 May 2004, Fabio Panizzutti wrote:
+
+
+> I don't understand why the planner chose a different query plan on
+> identical tables with same indexes .
+
+Because it's more than table structure that affects the choice made by the
+planner.  In addition the statistics about the values that are there as
+well as the estimated size of the table have effects.  One way to see is
+to see what it thinks is best is to remove the indexes it is using and see
+what plan it gives then, how long it takes and the estimated costs for
+those plans.
+
+In other suggestions, I think having a (tag_id, data_tag) index rather
+than (data_tag, tag_id) may be a win for queries like this. Also, unless
+you're doing many select queries by only the first field of the composite
+index and you're not doing very many insert/update/deletes, you may want
+to drop the other index on just that field.
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 16:42:52 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Thu, 13 May 2004 15:42:20 -0400
+To: pgsql-performance@postgresql.org
+From: Doug Y 
+Subject: Re: Clarification on some settings
+Mime-Version: 1.0
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+
+(Sorry if this ends up being a duplicate post, I sent a reply yesterday, 
+but it doesn't appear to have gone through... I think I typo'd the address 
+but never got a bounce.)
+
+Hi,
+   Thanks for your initial help. I have some more questions below.
+
+At 05:02 AM 5/12/2004, Shridhar Daithankar wrote:
+>Doug Y wrote:
+>
+>>Hello,
+>>   I've been having some performance issues with a DB I use. I'm trying 
+>> to come up with some performance recommendations to send to the "adminstrator".
+>>
+>>Ok for what I'm uncertain of...
+>>shared_buffers:
+>>According to http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+>>Its more of a staging area and more isn't necessarily better. That psql 
+>>relies on the OS to cache data for later use.
+>>But according to 
+>>http://www.ca.postgresql.org/docs/momjian/hw_performance/node3.html its 
+>>where psql caches previous data for queries because the OS cache is 
+>>slower, and should be as big as possible without causing swap.
+>>Those seem to be conflicting statements. In our case, the "administrator" 
+>>kept increasing this until performance seemed to increase, which means 
+>>its now 250000 (x 8k is 2G).
+>>Is this just a staging area for data waiting to move to the OS cache, or 
+>>is this really the area that psql caches its data?
+>
+>It is the area where postgresql works. It updates data in this area and 
+>pushes it to OS cache for disk writes later.
+>
+>By experience, larger does not mean better for this parameter. For 
+>multi-Gig RAM machines, the best(on an average for wide variety of load) 
+>value found to be around 10000-15000. May be even lower.
+>
+>It is a well known fact that raising this parameter unnecessarily 
+>decreases the performance. You indicate that best performance occurred at 
+>250000. This is very very large compared to other people's experience.
+
+Ok. I think I understand a bit better now.
+
+>>effective_cache_size:
+>>Again, according to the Varlena guide this tells psql how much system 
+>>memory is available for it to do its work in.
+>>until recently, this was set at the default value of 1000. It was just 
+>>recently increased to 180000 (1.5G)
+>>according to 
+>>http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html 
+>>it should be about 25% of memory?
+>
+>No rule of thumb. It is amount of memory OS will dedicate to psotgresql 
+>data buffers. Depending uponn what else you run on machine, it could be 
+>straight-forward or noodly value to calculate. For a 4GB machine, 1.5GB is 
+>quite good but coupled with 2G of shared buffers it could push the 
+>machines to swap storm. And swapping shared buffers is a big performance hit.
+
+We don't seem to be swapping much:
+
+# top
+
+   2:21pm  up 236 days, 19:12,  1 user,  load average: 1.45, 1.09, 1.00
+53 processes: 51 sleeping, 2 running, 0 zombie, 0 stopped
+CPU0 states: 30.3% user,  9.1% system,  0.0% nice, 60.0% idle
+CPU1 states: 32.0% user,  9.3% system,  0.0% nice, 58.1% idle
+Mem:  3863468K av, 3845844K used,   17624K free, 2035472K shrd,  198340K buff
+Swap: 1052248K av,    1092K used, 1051156K free                 1465112K cached
+
+looks like at some point it did swap a little, but from running vmstat, I 
+can't seem to catch it actively swapping.
+
+>>Finally sort_mem:
+>>Was until recently left at the default of 1000. Is now 16000.
+>
+>Sort memory is per sort not per query or per connection. So depending upon 
+>how many concurrent connections you entertain, it could take quite a chuck 
+>of RAM.
+
+Right I understand that. How does one calculate the size of a sort? Rows * 
+width from an explain?
+
+>>Increasing the effective cache and sort mem didn't seem to make much of a 
+>>difference. I'm guessing the eff cache was probably raised a bit too 
+>>much, and shared_buffers is way to high.
+>
+>I agree. For shared buffers start with 5000 and increase in batches on 
+>1000. Or set it to a high value and check with ipcs for maximum shared 
+>memory usage. If share memory usage peaks at 100MB, you don't need more 
+>than say 120MB of buffers.
+
+My results from ipcs seems confusing... says its using the full 2G of 
+shared cache:
+
+# ipcs
+
+------ Shared Memory Segments --------
+key        shmid      owner      perms      bytes      nattch     status
+0x0052e2c1 6389760    postgres  600        2088370176 4
+
+------ Semaphore Arrays --------
+key        semid      owner      perms      nsems      status
+0x0052e2c1 424378368  postgres  600        17
+0x0052e2c2 424411137  postgres  600        17
+0x0052e2c3 424443906  postgres  600        17
+0x0052e2c4 424476675  postgres  600        17
+0x0052e2c5 424509444  postgres  600        17
+0x0052e2c6 424542213  postgres  600        17
+0x0052e2c7 424574982  postgres  600        17
+0x0052e2c8 424607751  postgres  600        17
+0x0052e2c9 424640520  postgres  600        17
+0x0052e2ca 424673289  postgres  600        17
+0x0052e2cb 424706058  postgres  600        17
+0x0052e2cc 424738827  postgres  600        17
+0x0052e2cd 424771596  postgres  600        17
+0x0052e2ce 424804365  postgres  600        17
+0x0052e2cf 424837134  postgres  600        17
+0x0052e2d0 424869903  postgres  600        17
+0x0052e2d1 424902672  postgres  600        17
+0x00018d45 505544721  root      777        1
+
+------ Message Queues --------
+key        msqid      owner      perms      used-bytes   messages
+
+
+>>What can I do to help determine what the proper settings should be and/or 
+>>look at other possible choke points. What should I look for in iostat, 
+>>mpstat, or vmstat as red flags that cpu, memory, or i/o bound?
+>
+>Yes. vmstat is usually a lot of help to locate the bottelneck.
+
+What would I be looking for here?
+
+# vmstat 2 10
+    procs                      memory    swap          io     system 
+  cpu
+  r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us 
+sy  id
+  0  0  0   1092  14780 198120 1467164   0   0     0    0   0     0   0  0   0
+  0  0  0   1092  19488 198120 
+1467204   0   0     0    0  240   564  11   5  84
+  0  0  0   1092  19520 198120 
+1467300   0   0     0   210  443  1094  29   8  63
+  0  0  0   1092  15832 198120 
+1467356   0   0     4   110  368  1455  27   5  68
+  3  0  0   1092  10956 198120 
+1467464   0   0     4   336  417  1679  33  10  57
+  1  0  0   1092  17840 198124 
+1465980   0   0  200   334  581  1914  63  14  23
+  1  0  0   1092  16556 198124 
+1466012   0   0     0   226  397  1069  30   4  66
+  0  0  0   1092  19096 198124 
+1466028   0   0     0   160  230   314  12   2  86
+  2  0  1   1092  16100 198128 
+1466748   0   0    28  1484  711  1578  23  12  65
+  0  0  0   1092  20140 198128 
+1466780   0   0     0   414  291   746  15   8  77
+
+I'm guessing what I should look at is the io: bi & bo ? when I run some 
+particularly large queries I see bo activity so I'm speculating that that 
+means its reading pages from disk, correct?
+
+>>DB maintenance wise, I don't believe they were running vacuum full until 
+>>I told them a few months ago that regular vacuum analyze no longer cleans 
+>>out dead tuples. Now normal vac is run daily, vac full weekly 
+>>(supposedly). How can I tell from the output of vacuum if the vac fulls 
+>>aren't being done, or not done often enough? Or from the system tables, 
+>>what can I read?
+>
+>In 7.4 you can do vacuum full verbose and it will tell you the stats at 
+>the end. For 7.3.x, its not there.
+>
+>I suggest you vacuum full database once.(For large database, dumping 
+>restoring might work faster. Dump/restore and vacuum full both lock the 
+>database exclusively i.e. downtime. So I guess faster the better for you. 
+>But there is no tool/guideline to determine which way to go.)
+
+Ok they had not done a full vacuum in a long time. I them run vacuumdb 
+--full --analyze --verbose and dump it into a file. What should I look for 
+to see if it was useful?
+
+for example:
+INFO:  Pages 118200: Changed 74, reaped 117525, Empty 0, New 0; Tup 575298: 
+Vac 11006, Keep/VTL 0/0, UnUsed 2454159, MinLen 68, MaxLen 1911; Re-using: 
+Free/Avai
+l. Space 774122944/774122944; EndEmpty/Avail. Pages 0/118200.
+         CPU 9.41s/1.33u sec elapsed 97.35 sec.
+
+Is there any documentation on what those numbers represent?
+
+Also do we need to use REINDEX on the indexes, or does vacuum full take 
+case of that?
+
+
+>>Is there anywhere else I can look for possible clues? I have access to 
+>>the DB super-user, but not the system root/user.
+>
+>Other than hardware tuning, find out slow/frequent queries. Use explain 
+>analyze to determine why they are so slow. Forgetting to typecast a where 
+>clause and using sequential scan could cost you lot more than mistuned 
+>postgresql configuration.
+
+Right. One example I can think of is one particular query takes about 120 
+seconds to run (explain analyze), but if I set enable_seqscan to off, it 
+takes about 10 seconds.
+
+>>Thank you for your time. Please let me know any help or suggestions you 
+>>may have. Unfortunately upgrading postgres, OS, kernel, or re-writing 
+>>schema is most likely not an option.
+>
+>I hope you can change your queries.
+
+For the most part we're not having too much trouble, just some newer 
+queries were building for some new features is what we're seeing trouble with.
+
+
+>HTH
+>
+>  Shridhar
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 13 17:28:35 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Subject: Re: Clarification on some settings
+From: Greg Copeland 
+To: Doug Y 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: <6.0.1.1.2.20040513153548.01edaec0@mail.ptd.net>
+References: <6.0.1.1.2.20040513153548.01edaec0@mail.ptd.net>
+Content-Type: text/plain
+Organization: Copeland Computer Consulting
+Message-Id: <1084480091.2227.20.camel@shrew.copelandconsulting.net>
+Mime-Version: 1.0
+X-Mailer: Ximian Evolution 1.4.4-8mdk 
+Date: Thu, 13 May 2004 15:28:11 -0500
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+
+On Thu, 2004-05-13 at 14:42, Doug Y wrote:
+
+
+> We don't seem to be swapping much:
+> 
+
+Linux aggressively swaps.  If you have any process in memory which is
+sleeping a lot, Linux may actively attempt to page it out.  This is true
+even when you are not low on memory.  Just because you see some swap
+space being used, does not mean that your actively running processes are
+causing your system to swap.
+
+I didn't catch what kernel version you are running, so I'm tossing this
+out there.  Depending on the kernel (I believe 2.6+, but there may be
+something like it in older kernels) that you are running, you can
+attempt to tune this buy setting a value of 0-100 in
+/proc/sys/vm/swappiness.  The higher the number, the more aggressive the
+kernel will attempt to swap.  Some misc. kernel patches attempt to
+dynamically tune this parameter.
+
+For a dedicated DB server, a higher number will probably be better. 
+This is because it should result in the most cache being available to
+the system.  This, of course means, you may have to wait an tad bit long
+when you ssh into the system, assuming sshd was swapped out.  I think
+you get the idea.
+
+
+> Swap: 1052248K av,    1092K used, 1051156K free                 1465112K cached
+> 
+> looks like at some point it did swap a little, but from running vmstat, I 
+> can't seem to catch it actively swapping.
+> 
+
+Chances are, you have some dormant process which is partially or
+completely paged out.
+
+For an interesting read on Linux and swapping, you can find out more
+here:  http://kerneltrap.org/node/view/3080.
+
+Cheers!
+
+-- 
+Greg Copeland, Owner
+greg@copelandconsulting.net
+Copeland Computer Consulting
+940.206.8004
+
+
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 18:01:09 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A3E250.2020204@jamesthornton.com>
+Date: Thu, 13 May 2004 16:02:08 -0500
+From: James Thornton 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.4) Gecko/20030624 Netscape/7.1 (ax)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Bjoern Metzdorf 
+Cc: pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Re: [PERFORM] Quad processor options - summary
+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+In-Reply-To: <40A2A7FA.6060403@turtle-entertainment.de>
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+
+Bjoern Metzdorf wrote:
+
+> Hi,
+> 
+> at first, many thanks for your valuable replies. On my quest for the 
+> ultimate hardware platform I'll try to summarize the things I learned.
+> 
+> -------------------------------------------------------------
+
+> This is what I am considering the ultimate platform for postgresql:
+> 
+> Hardware:
+> Tyan Thunder K8QS board
+> 2-4 x Opteron 848 in NUMA mode
+> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+> channels (3 + 4) for pgdata including indexes and wal.
+
+You might also consider configuring the Postgres data drives for a RAID 
+10 SAME configuration as described in the Oracle paper "Optimal Storage 
+Configuration Made Easy" 
+(http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+anyone delved into this before?
+
+-- 
+
+  James Thornton
+______________________________________________________
+Internet Business Consultant, http://jamesthornton.com
+
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 18:53:58 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A3EE5B.1050104@turtle-entertainment.de>
+Date: Thu, 13 May 2004 23:53:31 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: James Thornton 
+Cc: pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Re: [PERFORM] Quad processor options - summary
+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+	<40A3E250.2020204@jamesthornton.com>
+In-Reply-To: <40A3E250.2020204@jamesthornton.com>
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+X-Sequence-Number: 13452
+
+James Thornton wrote:
+
+>> This is what I am considering the ultimate platform for postgresql:
+>>
+>> Hardware:
+>> Tyan Thunder K8QS board
+>> 2-4 x Opteron 848 in NUMA mode
+>> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+>> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+>> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+>> channels (3 + 4) for pgdata including indexes and wal.
+> 
+> You might also consider configuring the Postgres data drives for a RAID 
+> 10 SAME configuration as described in the Oracle paper "Optimal Storage 
+> Configuration Made Easy" 
+> (http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+> anyone delved into this before?
+
+Ok, if I understand it correctly the papers recommends the following:
+
+1. Get many drives and stripe them into a RAID0 with a stripe width of 
+1MB. I am not quite sure if this stripe width is to be controlled at the 
+application level (does postgres support this?) or if e.g. the "chunk 
+size" of the linux software driver is meant. Normally a chunk size of 
+4KB is recommended, so 1MB sounds fairly large.
+
+2. Mirror your RAID0 and get a RAID10.
+
+3. Use primarily the fast, outer regions of your disks. In practice this 
+might be achieved by putting only half of the disk (the outer half) into 
+your stripe set. E.g. put only the outer 18GB of your 36GB disks into 
+the stripe set. Btw, is it common for all drives that the outer region 
+is on the higher block numbers? Or is it sometimes on the lower block 
+numbers?
+
+4. Subset data by partition, not disk. If you have 8 disks, then don't 
+take a 4 disk RAID10 for data and the other one for log or indexes, but 
+make a global 8 drive RAID10 and have it partitioned the way that data 
+and log + indexes are located on all drives.
+
+They say, which is very interesting, as it is really contrary to what is 
+normally recommended, that it is good or better to have one big stripe 
+set over all disks available, than to put log + indexes on a separated 
+stripe set. Having one big stripe set means that the speed of this big 
+stripe set is available to all data. In practice this setup is as fast 
+as or even faster than the "old" approach.
+
+----------------------------------------------------------------
+
+Bottom line for a normal, less than 10 disk setup:
+
+Get many disks (8 + spare), create a RAID0 with 4 disks and mirror it to 
+the other 4 disks for a RAID10. Make sure to create the RAID on the 
+outer half of the disks (setup may depend on the disk model and raid 
+controller used), leaving the inner half empty.
+Use a logical volume manager (LVM), which always helps when adding disk 
+space, and create 2 partitions on your RAID10. One for data and one for 
+log + indexes. This should look like this:
+
+----- ----- ----- -----
+| 1 | | 1 | | 1 | | 1 |
+----- ----- ----- -----  <- outer, faster half of the disk
+| 2 | | 2 | | 2 | | 2 |     part of the RAID10
+----- ----- ----- -----
+|   | |   | |   | |   |
+|   | |   | |   | |   |  <- inner, slower half of the disk
+|   | |   | |   | |   |     not used at all
+----- ----- ----- -----
+
+Partition 1 for data, partition 2 for log + indexes. All mirrored to the 
+other 4 disks not shown.
+
+If you take 36GB disks, this should end up like this:
+
+RAID10 has size of 36 / 2 * 4 = 72GB
+Partition 1 is 36 GB
+Partition 2 is 36 GB
+
+If 36GB is not enough for your pgdata set, you might consider moving to 
+72GB disks, or (even better) make a 16 drive RAID10 out of 36GB disks, 
+which both will end up in a size of 72GB for your data (but the 16 drive 
+version will be faster).
+
+Any comments?
+
+Regards,
+Bjoern
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 19:49:41 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A3FBC5.8090301@jamesthornton.com>
+Date: Thu, 13 May 2004 17:50:45 -0500
+From: James Thornton 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.4) Gecko/20030624 Netscape/7.1 (ax)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Bjoern Metzdorf 
+Cc: pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Re: [PERFORM] Quad processor options - summary
+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+	<40A3E250.2020204@jamesthornton.com>
+	<40A3EE5B.1050104@turtle-entertainment.de>
+In-Reply-To: <40A3EE5B.1050104@turtle-entertainment.de>
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+X-Spam-Level: 
+X-Archive-Number: 200405/137
+X-Sequence-Number: 13453
+
+Bjoern Metzdorf wrote:
+
+>> You might also consider configuring the Postgres data drives for a 
+>> RAID 10 SAME configuration as described in the Oracle paper "Optimal 
+>> Storage Configuration Made Easy" 
+>> (http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+>> anyone delved into this before?
+> 
+> Ok, if I understand it correctly the papers recommends the following:
+> 
+> 1. Get many drives and stripe them into a RAID0 with a stripe width of 
+> 1MB. I am not quite sure if this stripe width is to be controlled at the 
+> application level (does postgres support this?) or if e.g. the "chunk 
+> size" of the linux software driver is meant. Normally a chunk size of 
+> 4KB is recommended, so 1MB sounds fairly large.
+> 
+> 2. Mirror your RAID0 and get a RAID10.
+
+Don't use RAID 0+1 -- use RAID 1+0 instead. Performance is the same, but 
+if a disk fails in a RAID 0+1 configuration, you are left with a RAID 0 
+array. In a RAID 1+0 configuration, multiple disks can fail.
+
+A few weeks ago I called LSI asking about the Dell PERC4-Di card, which 
+is actually an LSI Megaraid 320-2. Dell's documentation said that its 
+support for RAID 10 was in the form of RAID-1 concatenated, but LSI said 
+that this is incorrect and that it supports RAID 10 proper.
+
+> 3. Use primarily the fast, outer regions of your disks. In practice this 
+> might be achieved by putting only half of the disk (the outer half) into 
+> your stripe set. E.g. put only the outer 18GB of your 36GB disks into 
+> the stripe set. 
+
+You can still use the inner-half of the drives, just relegate it to 
+less-frequently accessed data.
+
+You also need to consider the filesystem.
+
+SGI and IBM did a detailed study on Linux filesystem performance, which 
+included XFS, ext2, ext3 (various modes), ReiserFS, and JFS, and the 
+results are presented in a paper entitled "Filesystem Performance and 
+Scalability in Linux 2.4.17" 
+(http://oss.sgi.com/projects/xfs/papers/filesystem-perf-tm.pdf).
+
+The scaling and load are key factors when selecting a filesystem. Since 
+Postgres data is stored in large files, ReiserFS is not the ideal choice 
+since it has been optimized for small files. XFS is probably the best 
+choice for a database server running on a quad processor box.
+
+However, Dr. Bert Scalzo of Quest argues that general file system 
+benchmarks aren't ideal for benchmarking a filesystem for a database 
+server. In a paper entitled "Tuning an Oracle8i Database running Linux" 
+(http://otn.oracle.com/oramag/webcolumns/2002/techarticles/scalzo_linux02.html), 
+  he says, "The trouble with these tests-for example, Bonnie, Bonnie++, 
+Dbench, Iobench, Iozone, Mongo, and Postmark-is that they are basic file 
+system throughput tests, so their results generally do not pertain in 
+any meaningful fashion to the way relational database systems access 
+data files." Instead he suggests using these two well-known and widely 
+accepted database benchmarks:
+
+* AS3AP: a scalable, portable ANSI SQL relational database benchmark 
+that provides a comprehensive set of tests of database-processing power; 
+has built-in scalability and portability for testing a broad range of 
+systems; minimizes human effort in implementing and running benchmark 
+tests; and provides a uniform, metric, straightforward interpretation of 
+the results.
+
+* TPC-C: an online transaction processing (OLTP) benchmark that involves 
+a mix of five concurrent transactions of various types and either 
+executes completely online or queries for deferred execution. The 
+database comprises nine types of tables, having a wide range of record 
+and population sizes. This benchmark measures the number of transactions 
+per second.
+
+In the paper, Scalzo benchmarks ext2, ext3, ReiserFS, JFS, but not XFS. 
+Surprisingly ext3 won, but Scalzo didn't address scaling/load. The 
+results are surprising because most think ext3 is just ext2 with 
+journaling, thus having extra overhead from journaling.
+
+If you read papers on ext3, you'll discover that has some optimizations 
+that reduce disk head movement. For example, Daniel Robbins' "Advanced 
+filesystem implementor's guide, Part 7: Introducing ext3" 
+(http://www-106.ibm.com/developerworks/library/l-fs7/) says:
+
+"The approach that the [ext3 Journaling Block Device layer API] uses is 
+called physical journaling, which means that the JBD uses complete 
+physical blocks as the underlying currency for implementing the 
+journal...the use of full blocks allows ext3 to perform some additional 
+optimizations, such as "squishing" multiple pending IO operations within 
+a single block into the same in-memory data structure. This, in turn, 
+allows ext3 to write these multiple changes to disk in a single write 
+operation, rather than many. In addition, because the literal block data 
+is stored in memory, little or no massaging of the in-memory data is 
+required before writing it to disk, greatly reducing CPU overhead."
+
+I suspect that less writes may be the key factor in ext3 winning 
+Scalzo's DB benchmark. But as I said, Scalzo didn't benchmark XFS and he 
+didn't address scaling.
+
+XFS has a feature called delayed allocation that reduces IO 
+(http://www-106.ibm.com/developerworks/library/l-fs9/), and it scales 
+much better than ext3 so while I haven't tested it, I suspect that it 
+may be the ideal choice for large Linux DB servers:
+
+"XFS handles allocation by breaking it into a two-step process. First, 
+when XFS receives new data to be written, it records the pending 
+transaction in RAM and simply reserves an appropriate amount of space on 
+the underlying filesystem. However, while XFS reserves space for the new 
+data, it doesn't decide what filesystem blocks will be used to store the 
+data, at least not yet. XFS procrastinates, delaying this decision to 
+the last possible moment, right before this data is actually written to 
+disk.
+
+By delaying allocation, XFS gains many opportunities to optimize write 
+performance. When it comes time to write the data to disk, XFS can now 
+allocate free space intelligently, in a way that optimizes filesystem 
+performance. In particular, if a bunch of new data is being appended to 
+a single file, XFS can allocate a single, contiguous region on disk to 
+store this data. If XFS hadn't delayed its allocation decision, it may 
+have unknowingly written the data into multiple non-contiguous chunks, 
+reducing write performance significantly. But, because XFS delayed its 
+allocation decision, it was able to write the data in one fell swoop, 
+improving write performance as well as reducing overall filesystem 
+fragmentation.
+
+Delayed allocation also has another performance benefit. In situations 
+where many short-lived temporary files are created, XFS may never need 
+to write these files to disk at all. Since no blocks are ever allocated, 
+there's no need to deallocate any blocks, and the underlying filesystem 
+metadata doesn't even get touched."
+
+For further study, I have compiled a list of Linux filesystem resources 
+at: http://jamesthornton.com/hotlist/linux-filesystems/.
+
+-- 
+
+  James Thornton
+______________________________________________________
+Internet Business Consultant, http://jamesthornton.com
+
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 20:00:29 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	by gaia.sol.deeper.co.nz (8.11.6/8.11.6) with ESMTP id i4DMxGM15879;
+	Fri, 14 May 2004 10:59:16 +1200
+Subject: Re: [PERFORM] Quad processor options - summary
+From: Hadley Willan 
+To: Bjoern Metzdorf 
+Cc: James Thornton ,
+	pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+In-Reply-To: <40A3EE5B.1050104@turtle-entertainment.de>
+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+	<40A3E250.2020204@jamesthornton.com>
+	<40A3EE5B.1050104@turtle-entertainment.de>
+Content-Type: multipart/alternative; boundary="=-ohWxbOoNulLVxR9g8Rk7"
+Message-Id: <1084489156.5424.31.camel@atlas.sol.deeper.co.nz>
+Mime-Version: 1.0
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+Date: Fri, 14 May 2004 10:59:16 +1200
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Sequence-Number: 13454
+
+--=-ohWxbOoNulLVxR9g8Rk7
+Content-Type: text/plain
+Content-Transfer-Encoding: 7bit
+
+I see you've got an LSI Megaraid card with oodles of Cache.  However,
+don't underestimate the power of the software RAID implementation that
+Red Hat Linux comes with.
+
+We're using RHE 2.1 and I can recommend Red Hat Enterprise Linux if you
+want an excellent implementation of software RAID.  In fact we have
+found the software implementation more flexible than that of some
+expensive hardware controllers.  In addition there are also tools to
+enhance the base implementation even further, making setup and
+maintenance even easier.  An advantage of the software implementation is
+being able to RAID by partition, not necessarily entire disks.
+
+To answer question 1, if you use software raid the chunk size is part of
+the /etc/raidtab file that is used on initial container creation. 4KB is
+the standard and a LARGE chunk size of 1MB may affect performance if
+you're not writing down to blocks in that size continuously.  If you
+make it to big and you're constantly needing to write out smaller chunks
+of information, then you will find the disk "always" working and would
+be an inefficient use of the blocks. There is some free info around
+about calculating the ideal chunk size. Looking for "Calculating chunk
+size for RAID" through google.
+
+In the software implementation, after setup the raidtab is uncessary as
+the superblocks of the disks now contain their relevant information.
+As for the application knowing any of this, no, the application layers
+are entirely unaware of the lower implementation.  They simply function
+as normal by writing to directories that are now mounted a different
+way.  The kernel takes care of the underlying RAID writes and syncs.
+3 is easy to implement with software raid under linux.  You simply
+partition the drive like normal, mark the partitions you want to "raid"
+as 'fd' 'linux raid autodetect', then configure the /etc/raidtab and do
+a mkraid /dev/mdxx where mdxx is the matching partition for the raid
+setup.  You can map them anyway you want, but it can get confusing if
+you're mapping /dev/sda6 > /dev/sdb8 and calling it /dev/md7.
+We've found it easier to make them all line up,  /dev/sda6 > /dev/sdb6 >
+/dev/md6
+
+FYI, if you want better performance, use 15K SCSI disks, and make sure
+you've got more than 8MB of cache per disk.  Also, you're correct in
+splitting the drives across the channel, that's a trap for young players
+;-)
+
+Bjoern is right to recommend an LVM, it will allow you to dynamically
+allocate new size to the RAID volume when you add more disks.  However
+I've no experience in implementation with an LVM under the software RAID
+for Linux, though I believe it can be done. 
+
+The software RAID implementation allows you to stop and start software
+RAID devices as desired, add new hot spare disks to the containers as
+needed and rebuild containers on the fly. You can even change kernel
+options to speed up or slow down the sync speed when rebuilding the
+container.
+
+Anyway, have fun, cause striping is the hot rod of the RAID
+implementations ;-)
+
+Regards.
+    Hadley
+
+
+On Fri, 2004-05-14 at 09:53, Bjoern Metzdorf wrote:
+
+> James Thornton wrote:
+> 
+> >> This is what I am considering the ultimate platform for postgresql:
+> >>
+> >> Hardware:
+> >> Tyan Thunder K8QS board
+> >> 2-4 x Opteron 848 in NUMA mode
+> >> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+> >> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+> >> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+> >> channels (3 + 4) for pgdata including indexes and wal.
+> > 
+> > You might also consider configuring the Postgres data drives for a RAID 
+> > 10 SAME configuration as described in the Oracle paper "Optimal Storage 
+> > Configuration Made Easy" 
+> > (http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+> > anyone delved into this before?
+> 
+> Ok, if I understand it correctly the papers recommends the following:
+> 
+> 1. Get many drives and stripe them into a RAID0 with a stripe width of 
+> 1MB. I am not quite sure if this stripe width is to be controlled at the 
+> application level (does postgres support this?) or if e.g. the "chunk 
+> size" of the linux software driver is meant. Normally a chunk size of 
+> 4KB is recommended, so 1MB sounds fairly large.
+> 
+> 2. Mirror your RAID0 and get a RAID10.
+> 
+> 3. Use primarily the fast, outer regions of your disks. In practice this 
+> might be achieved by putting only half of the disk (the outer half) into 
+> your stripe set. E.g. put only the outer 18GB of your 36GB disks into 
+> the stripe set. Btw, is it common for all drives that the outer region 
+> is on the higher block numbers? Or is it sometimes on the lower block 
+> numbers?
+> 
+> 4. Subset data by partition, not disk. If you have 8 disks, then don't 
+> take a 4 disk RAID10 for data and the other one for log or indexes, but 
+> make a global 8 drive RAID10 and have it partitioned the way that data 
+> and log + indexes are located on all drives.
+> 
+> They say, which is very interesting, as it is really contrary to what is 
+> normally recommended, that it is good or better to have one big stripe 
+> set over all disks available, than to put log + indexes on a separated 
+> stripe set. Having one big stripe set means that the speed of this big 
+> stripe set is available to all data. In practice this setup is as fast 
+> as or even faster than the "old" approach.
+> 
+> ----------------------------------------------------------------
+> 
+> Bottom line for a normal, less than 10 disk setup:
+> 
+> Get many disks (8 + spare), create a RAID0 with 4 disks and mirror it to 
+> the other 4 disks for a RAID10. Make sure to create the RAID on the 
+> outer half of the disks (setup may depend on the disk model and raid 
+> controller used), leaving the inner half empty.
+> Use a logical volume manager (LVM), which always helps when adding disk 
+> space, and create 2 partitions on your RAID10. One for data and one for 
+> log + indexes. This should look like this:
+> 
+> ----- ----- ----- -----
+> | 1 | | 1 | | 1 | | 1 |
+> ----- ----- ----- -----  <- outer, faster half of the disk
+> | 2 | | 2 | | 2 | | 2 |     part of the RAID10
+> ----- ----- ----- -----
+> |   | |   | |   | |   |
+> |   | |   | |   | |   |  <- inner, slower half of the disk
+> |   | |   | |   | |   |     not used at all
+> ----- ----- ----- -----
+> 
+> Partition 1 for data, partition 2 for log + indexes. All mirrored to the 
+> other 4 disks not shown.
+> 
+> If you take 36GB disks, this should end up like this:
+> 
+> RAID10 has size of 36 / 2 * 4 = 72GB
+> Partition 1 is 36 GB
+> Partition 2 is 36 GB
+> 
+> If 36GB is not enough for your pgdata set, you might consider moving to 
+> 72GB disks, or (even better) make a 16 drive RAID10 out of 36GB disks, 
+> which both will end up in a size of 72GB for your data (but the 16 drive 
+> version will be faster).
+> 
+> Any comments?
+> 
+> Regards,
+> Bjoern
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 6: Have you searched our list archives?
+> 
+>                http://archives.postgresql.org
+
+--=-ohWxbOoNulLVxR9g8Rk7
+Content-Type: text/html; charset=utf-8
+Content-Transfer-Encoding: 7bit
+
+
+
+
+  
+  
+
+
+I see you've got an LSI Megaraid card with oodles of Cache.  However, don't underestimate the power of the software RAID implementation that Red Hat Linux comes with.

+

+We're using RHE 2.1 and I can recommend Red Hat Enterprise Linux if you want an excellent implementation of software RAID.  In fact we have found the software implementation more flexible than that of some expensive hardware controllers.  In addition there are also tools to enhance the base implementation even further, making setup and maintenance even easier.  An advantage of the software implementation is being able to RAID by partition, not necessarily entire disks.

+

+To answer question 1, if you use software raid the chunk size is part of the /etc/raidtab file that is used on initial container creation. 4KB is the standard and a LARGE chunk size of 1MB may affect performance if you're not writing down to blocks in that size continuously.  If you make it to big and you're constantly needing to write out smaller chunks of information, then you will find the disk "always" working and would be an inefficient use of the blocks. There is some free info around about calculating the ideal chunk size. Looking for "Calculating chunk size for RAID" through google.

+

+In the software implementation, after setup the raidtab is uncessary as the superblocks of the disks now contain their relevant information.

+As for the application knowing any of this, no, the application layers are entirely unaware of the lower implementation.  They simply function as normal by writing to directories that are now mounted a different way.  The kernel takes care of the underlying RAID writes and syncs.

+3 is easy to implement with software raid under linux.  You simply partition the drive like normal, mark the partitions you want to "raid" as 'fd' 'linux raid autodetect', then configure the /etc/raidtab and do a mkraid /dev/mdxx where mdxx is the matching partition for the raid setup.  You can map them anyway you want, but it can get confusing if you're mapping /dev/sda6 > /dev/sdb8 and calling it /dev/md7.

+We've found it easier to make them all line up,  /dev/sda6 > /dev/sdb6 > /dev/md6

+

+FYI, if you want better performance, use 15K SCSI disks, and make sure you've got more than 8MB of cache per disk.  Also, you're correct in splitting the drives across the channel, that's a trap for young players ;-)

+

+Bjoern is right to recommend an LVM, it will allow you to dynamically allocate new size to the RAID volume when you add more disks.  However I've no experience in implementation with an LVM under the software RAID for Linux, though I believe it can be done. 

+

+The software RAID implementation allows you to stop and start software RAID devices as desired, add new hot spare disks to the containers as needed and rebuild containers on the fly. You can even change kernel options to speed up or slow down the sync speed when rebuilding the container.

+

+Anyway, have fun, cause striping is the hot rod of the RAID implementations ;-)

+

+Regards.

+    Hadley

+

+

+On Fri, 2004-05-14 at 09:53, Bjoern Metzdorf wrote:
+

+
James Thornton wrote:
+
+>> This is what I am considering the ultimate platform for postgresql:
+>>
+>> Hardware:
+>> Tyan Thunder K8QS board
+>> 2-4 x Opteron 848 in NUMA mode
+>> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+>> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+>> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over both 
+>> channels (3 + 4) for pgdata including indexes and wal.
+> 
+> You might also consider configuring the Postgres data drives for a RAID 
+> 10 SAME configuration as described in the Oracle paper "Optimal Storage 
+> Configuration Made Easy" 
+> (http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+> anyone delved into this before?
+
+Ok, if I understand it correctly the papers recommends the following:
+
+1. Get many drives and stripe them into a RAID0 with a stripe width of 
+1MB. I am not quite sure if this stripe width is to be controlled at the 
+application level (does postgres support this?) or if e.g. the "chunk 
+size" of the linux software driver is meant. Normally a chunk size of 
+4KB is recommended, so 1MB sounds fairly large.
+
+2. Mirror your RAID0 and get a RAID10.
+
+3. Use primarily the fast, outer regions of your disks. In practice this 
+might be achieved by putting only half of the disk (the outer half) into 
+your stripe set. E.g. put only the outer 18GB of your 36GB disks into 
+the stripe set. Btw, is it common for all drives that the outer region 
+is on the higher block numbers? Or is it sometimes on the lower block 
+numbers?
+
+4. Subset data by partition, not disk. If you have 8 disks, then don't 
+take a 4 disk RAID10 for data and the other one for log or indexes, but 
+make a global 8 drive RAID10 and have it partitioned the way that data 
+and log + indexes are located on all drives.
+
+They say, which is very interesting, as it is really contrary to what is 
+normally recommended, that it is good or better to have one big stripe 
+set over all disks available, than to put log + indexes on a separated 
+stripe set. Having one big stripe set means that the speed of this big 
+stripe set is available to all data. In practice this setup is as fast 
+as or even faster than the "old" approach.
+
+----------------------------------------------------------------
+
+Bottom line for a normal, less than 10 disk setup:
+
+Get many disks (8 + spare), create a RAID0 with 4 disks and mirror it to 
+the other 4 disks for a RAID10. Make sure to create the RAID on the 
+outer half of the disks (setup may depend on the disk model and raid 
+controller used), leaving the inner half empty.
+Use a logical volume manager (LVM), which always helps when adding disk 
+space, and create 2 partitions on your RAID10. One for data and one for 
+log + indexes. This should look like this:
+
+----- ----- ----- -----
+| 1 | | 1 | | 1 | | 1 |
+----- ----- ----- -----  <- outer, faster half of the disk
+| 2 | | 2 | | 2 | | 2 |     part of the RAID10
+----- ----- ----- -----
+|   | |   | |   | |   |
+|   | |   | |   | |   |  <- inner, slower half of the disk
+|   | |   | |   | |   |     not used at all
+----- ----- ----- -----
+
+Partition 1 for data, partition 2 for log + indexes. All mirrored to the 
+other 4 disks not shown.
+
+If you take 36GB disks, this should end up like this:
+
+RAID10 has size of 36 / 2 * 4 = 72GB
+Partition 1 is 36 GB
+Partition 2 is 36 GB
+
+If 36GB is not enough for your pgdata set, you might consider moving to 
+72GB disks, or (even better) make a 16 drive RAID10 out of 36GB disks, 
+which both will end up in a size of 72GB for your data (but the 16 drive 
+version will be faster).
+
+Any comments?
+
+Regards,
+Bjoern
+
+---------------------------(end of broadcast)---------------------------
+TIP 6: Have you searched our list archives?
+
+               http://archives.postgresql.org

+

+
+
+
+--=-ohWxbOoNulLVxR9g8Rk7--
+
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 20:35:16 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40A40670.5030901@jamesthornton.com>
+Date: Thu, 13 May 2004 18:36:16 -0500
+From: James Thornton 
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.4) Gecko/20030624 Netscape/7.1 (ax)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Hadley Willan 
+Cc: Bjoern Metzdorf ,
+	pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Subject: Re: [PERFORM] Quad processor options - summary
+References: 	
+	<40A2A7FA.6060403@turtle-entertainment.de>	
+	<40A3E250.2020204@jamesthornton.com>	
+	<40A3EE5B.1050104@turtle-entertainment.de>
+	<1084489156.5424.31.camel@atlas.sol.deeper.co.nz>
+In-Reply-To: <1084489156.5424.31.camel@atlas.sol.deeper.co.nz>
+Content-Type: text/plain; charset=windows-1252; format=flowed
+Content-Transfer-Encoding: quoted-printable
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+X-Spam-Level: 
+X-Archive-Number: 200405/139
+X-Sequence-Number: 13455
+
+Hadley Willan wrote:
+
+> To answer question 1, if you use software raid the chunk size is part of=
+=20
+> the /etc/raidtab file that is used on initial container creation. 4KB is=
+=20
+> the standard and a LARGE chunk size of 1MB may affect performance if=20
+> you're not writing down to blocks in that size continuously.  If you=20
+> make it to big and you're constantly needing to write out smaller chunks=
+=20
+> of information, then you will find the disk "always" working and would=20
+> be an inefficient use of the blocks. There is some free info around=20
+> about calculating the ideal chunk size. Looking for "Calculating chunk=20
+> size for RAID" through google.
+
+"Why does the SAME configuration recommend a one megabyte stripe width?=20
+Let=92s examine the reasoning behind this choice. Why not use a stripe=20
+depth smaller than one megabyte? Smaller stripe depths can improve disk=20
+throughput for a single process by spreading a single IO across multiple=20
+disks. However IOs that are much smaller than a megabyte can cause seek=20
+time to becomes a large fraction of the total IO time. Therefore, the=20
+overall efficiency of the storage system is reduced. In some cases it=20
+may be worth trading off some efficiency for the increased throughput=20
+that smaller stripe depths provide. In general it is not necessary to do=20
+this though. Parallel execution at database level achieves high disk=20
+throughput while keeping efficiency high. Also, remember that the degree=20
+of parallelism can be dynamically tuned, whereas the stripe depth is=20
+very costly to change.
+
+Why not use a stripe depth bigger than one megabyte? One megabyte is=20
+large enough that a sequential scan will spend most of its time=20
+transferring data instead of positioning the disk head. A bigger stripe=20
+depth will improve scan efficiency but only modestly. One megabyte is=20
+small enough that a large IO operation will not =93hog=94 a single disk for=
+=20
+very long before moving to the next one. Further, one megabyte is small=20
+enough that Oracle=92s asynchronous readahead operations access multiple=20
+disks. One megabyte is also small enough that a single stripe unit will=20
+not become a hot-spot. Any access hot-spot that is smaller than a=20
+megabyte should fit comfortably in the database buffer cache. Therefore=20
+it will not create a hot-spot on disk."
+
+The SAME configuration paper says to ensure that that large IO=20
+operations aren't broken up between the DB and the disk, you need to be=20
+able to ensure that the database file multi-block read count (Oracle has=20
+a param called db_file_multiblock_read_count, does Postgres?) is the=20
+same size as the stripe width and the OS IO limits should be at least=20
+this size.
+
+Also, it says, "Ideally we would like to stripe the log files using the=20
+same one megabyte stripe width as the rest of the files. However, the=20
+log files are written sequentially, and many storage systems limit the=20
+maximum size of a single write operation to one megabyte (or even less).=20
+If the maximum write size is limited, then using a one megabyte stripe=20
+width for the log files may not work well. In this case, a smaller=20
+stripe width such as 64K may work better. Caching RAID controllers are=20
+an exception to this. If the storage subsystem can cache write=20
+operations in nonvolatile RAM, then a one megabyte stripe width will=20
+work well for the log files. In this case, the write operation will be=20
+buffered in cache and the next log writes can be issued before the=20
+previous write is destaged to disk."
+
+
+--=20
+
+  James Thornton
+______________________________________________________
+Internet Business Consultant, http://jamesthornton.com
+
+
+From pgsql-admin-owner@postgresql.org  Thu May 13 21:52:07 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+	<40A3E250.2020204@jamesthornton.com>
+	<40A3EE5B.1050104@turtle-entertainment.de>
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+Cc: pgsql-admin@postgresql.org, James Thornton ,
+	pgsql-performance@postgresql.org
+From: Paul Tuckfield 
+Subject: Re: [PERFORM] Quad processor options - summary
+Date: Thu, 13 May 2004 17:51:42 -0700
+To: Bjoern Metzdorf 
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+
+One big caveat re. the "SAME" striping strategy, is that readahead can 
+really hurt an OLTP you.
+
+Mind you, if you're going from a few disks to a caching array with many 
+disks, it'll be hard to not have a big improvement
+
+But if you push the envelope of the array with a "SAME" configuration, 
+readahead will hurt.  Readahead is good for sequential reads but bad 
+for random reads, because the various caches (array and filesystem) get 
+flooded with all the blocks that happen to come after whatever random 
+blocks  you're reading.  Because they're random reads these extra 
+blocks are genarally *not* read by subsequent queries if the database 
+is large enough to be much larger than the cache itself.   Of course, 
+the readahead blocks are good if you're doing sequential scans, but 
+you're not doing sequential scans because it's an OLTP database, right?
+
+
+So this'll probably incite flames but:
+In an OLTP environment of decent size, readahead is bad.  The ideal 
+would be to adjust it dynamically til optimum (likely no readahead)  if 
+the array allows it, but most people are fooled by good performance of 
+readahead on simple singlethreaded or small dataset tests, and get 
+bitten by this under concurrent loads or large datasets.
+
+
+James Thornton wrote:
+>
+>>> This is what I am considering the ultimate platform for postgresql:
+>>>
+>>> Hardware:
+>>> Tyan Thunder K8QS board
+>>> 2-4 x Opteron 848 in NUMA mode
+>>> 4-8 GB RAM (DDR400 ECC Registered 1 GB modules, 2 for each processor)
+>>> LSI Megaraid 320-2 with 256 MB cache ram and battery backup
+>>> 6 x 36GB SCSI 10K drives + 1 spare running in RAID 10, split over 
+>>> both channels (3 + 4) for pgdata including indexes and wal.
+>> You might also consider configuring the Postgres data drives for a 
+>> RAID 10 SAME configuration as described in the Oracle paper "Optimal 
+>> Storage Configuration Made Easy" 
+>> (http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf). Has 
+>> anyone delved into this before?
+>
+> Ok, if I understand it correctly the papers recommends the following:
+>
+> 1. Get many drives and stripe them into a RAID0 with a stripe width of 
+> 1MB. I am not quite sure if this stripe width is to be controlled at 
+> the application level (does postgres support this?) or if e.g. the 
+> "chunk size" of the linux software driver is meant. Normally a chunk 
+> size of 4KB is recommended, so 1MB sounds fairly large.
+>
+> 2. Mirror your RAID0 and get a RAID10.
+>
+> 3. Use primarily the fast, outer regions of your disks. In practice 
+> this might be achieved by putting only half of the disk (the outer 
+> half) into your stripe set. E.g. put only the outer 18GB of your 36GB 
+> disks into the stripe set. Btw, is it common for all drives that the 
+> outer region is on the higher block numbers? Or is it sometimes on the 
+> lower block numbers?
+>
+> 4. Subset data by partition, not disk. If you have 8 disks, then don't 
+> take a 4 disk RAID10 for data and the other one for log or indexes, 
+> but make a global 8 drive RAID10 and have it partitioned the way that 
+> data and log + indexes are located on all drives.
+>
+> They say, which is very interesting, as it is really contrary to what 
+> is normally recommended, that it is good or better to have one big 
+> stripe set over all disks available, than to put log + indexes on a 
+> separated stripe set. Having one big stripe set means that the speed 
+> of this big stripe set is available to all data. In practice this 
+> setup is as fast as or even faster than the "old" approach.
+>
+> ----------------------------------------------------------------
+>
+> Bottom line for a normal, less than 10 disk setup:
+>
+> Get many disks (8 + spare), create a RAID0 with 4 disks and mirror it 
+> to the other 4 disks for a RAID10. Make sure to create the RAID on the 
+> outer half of the disks (setup may depend on the disk model and raid 
+> controller used), leaving the inner half empty.
+> Use a logical volume manager (LVM), which always helps when adding 
+> disk space, and create 2 partitions on your RAID10. One for data and 
+> one for log + indexes. This should look like this:
+>
+> ----- ----- ----- -----
+> | 1 | | 1 | | 1 | | 1 |
+> ----- ----- ----- -----  <- outer, faster half of the disk
+> | 2 | | 2 | | 2 | | 2 |     part of the RAID10
+> ----- ----- ----- -----
+> |   | |   | |   | |   |
+> |   | |   | |   | |   |  <- inner, slower half of the disk
+> |   | |   | |   | |   |     not used at all
+> ----- ----- ----- -----
+>
+> Partition 1 for data, partition 2 for log + indexes. All mirrored to 
+> the other 4 disks not shown.
+>
+> If you take 36GB disks, this should end up like this:
+>
+> RAID10 has size of 36 / 2 * 4 = 72GB
+> Partition 1 is 36 GB
+> Partition 2 is 36 GB
+>
+> If 36GB is not enough for your pgdata set, you might consider moving 
+> to 72GB disks, or (even better) make a 16 drive RAID10 out of 36GB 
+> disks, which both will end up in a size of 72GB for your data (but the 
+> 16 drive version will be faster).
+>
+> Any comments?
+>
+> Regards,
+> Bjoern
+>
+> ---------------------------(end of 
+> broadcast)---------------------------
+> TIP 3: if posting/reading through Usenet, please send an appropriate
+>      subscribe-nomail command to majordomo@postgresql.org so that your
+>      message can get through to the mailing list cleanly
+>
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 05:30:55 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 1BOYC4-0007sL-00; Fri, 14 May 2004 10:37:24 +0200
+From: "Fabio Panizzutti" 
+To: "'Tom Lane'" 
+Cc: 
+Subject: R: R: Query plan on identical tables differs . Why ? 
+Date: Fri, 14 May 2004 10:40:24 +0200
+Message-ID: <000f01c4398f$1a20cbc0$3c02020a@ufficio>
+MIME-Version: 1.0
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+	charset="iso-8859-1"
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+
+
+
+>>>-----Messaggio originale-----
+>>>Da: Tom Lane [mailto:tgl@sss.pgh.pa.us]=20
+>>>Inviato: gioved=EC 13 maggio 2004 17.01
+>>>A: Fabio Panizzutti
+>>>Cc: 'Shridhar Daithankar'; pgsql-performance@postgresql.org
+>>>Oggetto: Re: R: [PERFORM] Query plan on identical tables=20
+>>>differs . Why ?=20
+>>>
+>>>
+>>>"Fabio Panizzutti"  writes:
+>>>> I don't understand why the planner chose a different query plan on=20
+>>>> identical tables with same indexes .
+>>>
+>>>Different data statistics; not to mention different table=20
+>>>sizes (the cost equations are not linear).
+>>>
+>>>Have you ANALYZEd (or VACUUM ANALYZEd) both tables recently?
+>>>
+>>>If the stats are up to date but still not doing the right=20
+>>>thing, you might try increasing the statistics target for=20
+>>>the larger table's tag_id column.  See ALTER TABLE SET STATISTICS.
+>>>
+>>>			regards, tom lane
+>>>
+
+All tables are vacumed and analyzed .=20
+I try so set statistics to 1000 to tag_id columns with ALTER TABLE SET
+STATISTIC, revacuum analyze ,  but the planner choose the same query
+plan .=20
+I'm trying now to change the indexes .
+
+Thanks=20
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 05:45:30 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 1BOYQJ-000890-00; Fri, 14 May 2004 10:52:07 +0200
+From: "Fabio Panizzutti" 
+To: "'Stephan Szabo'" 
+Cc: 
+Subject: R: R: Query plan on identical tables differs . Why ?
+Date: Fri, 14 May 2004 10:55:07 +0200
+Message-ID: <001001c43991$284506b0$3c02020a@ufficio>
+MIME-Version: 1.0
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+In-Reply-To: <20040513080130.E3465@megazone.bigpanda.com>
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+
+
+
+>>>-----Messaggio originale-----
+>>>Da: Stephan Szabo [mailto:sszabo@megazone.bigpanda.com]=20
+>>>Inviato: gioved=EC 13 maggio 2004 17.17
+>>>A: Fabio Panizzutti
+>>>Cc: 'Shridhar Daithankar'; pgsql-performance@postgresql.org
+>>>Oggetto: Re: R: [PERFORM] Query plan on identical tables=20
+>>>differs . Why ?
+>>>
+>>>
+>>>On Thu, 13 May 2004, Fabio Panizzutti wrote:
+>>>
+>>>
+>>>> I don't understand why the planner chose a different query plan on=20
+>>>> identical tables with same indexes .
+>>>
+>>>Because it's more than table structure that affects the=20
+>>>choice made by the planner.  In addition the statistics=20
+>>>about the values that are there as well as the estimated=20
+>>>size of the table have effects.  One way to see is to see=20
+>>>what it thinks is best is to remove the indexes it is using=20
+>>>and see what plan it gives then, how long it takes and the=20
+>>>estimated costs for those plans.
+>>>
+>>>In other suggestions, I think having a (tag_id, data_tag)=20
+>>>index rather than (data_tag, tag_id) may be a win for=20
+>>>queries like this. Also, unless you're doing many select=20
+>>>queries by only the first field of the composite index and=20
+>>>you're not doing very many insert/update/deletes, you may=20
+>>>want to drop the other index on just that field.
+>>>
+
+Thanks for your attention , i change the indexes on the tables as you
+suggested  :
+
+ storico=3D# \d storico_misure_short
+                Table "tenore.storico_misure_short"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "storico_misure_short_idx" primary key, btree (tag_id, data_tag)
+    "storico_misure_short_data_tag_idx2" btree (data_tag)
+
+storico=3D# \d storico_misure
+                   Table "tenore.storico_misure"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "storico_misure_idx" primary key, btree (tag_id, data_tag)
+    "storico_misure_data_tag_idx2" btree (data_tag)
+
+And now performance are similar and the planner works correctly :
+
+storico=3D# \d storico_misure_short
+                Table "tenore.storico_misure_short"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "storico_misure_short_idx" primary key, btree (tag_id, data_tag)
+    "storico_misure_short_data_tag_idx2" btree (data_tag)
+
+storico=3D# \d storico_misure
+                   Table "tenore.storico_misure"
+         Column          |            Type             | Modifiers
+-------------------------+-----------------------------+-----------
+ data_tag                | timestamp without time zone | not null
+ tag_id                  | integer                     | not null
+ unita_misura            | character varying(6)        | not null
+ valore_tag              | numeric(20,3)               | not null
+ qualita                 | integer                     | not null
+ numero_campioni         | numeric(5,0)                |
+ frequenza_campionamento | numeric(3,0)                |
+Indexes:
+    "storico_misure_idx" primary key, btree (tag_id, data_tag)
+    "storico_misure_data_tag_idx2" btree (data_tag)
+
+storico=3D# explain analyze select tag_id,valore_tag,data_tag from
+storico_misure_short where (data_tag>'2004-05-03' and data_tag
+<'2004-05-12') and tag_id=3D37423 ;
+=20
+QUERY PLAN
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+--------------------------
+ Index Scan using storico_misure_short_idx on storico_misure_short
+(cost=3D0.00..2104.47 rows=3D584 width=3D20) (actual time=3D0.232..39.932
+rows=3D864 loops=3D1)
+   Index Cond: ((tag_id =3D 37423) AND (data_tag > '2004-05-03
+00:00:00'::timestamp without time zone) AND (data_tag < '2004-05-12
+00:00:00'::timestamp without time zone))
+ Total runtime: 40.912 ms
+(3 rows)
+
+Time: 43,233 ms
+storico=3D# explain analyze select tag_id,valore_tag,data_tag from
+storico_misure where (data_tag>'2004-05-03' and data_tag <'2004-05-12')
+and tag_id=3D37423 ;
+=20
+QUERY PLAN
+------------------------------------------------------------------------
+------------------------------------------------------------------------
+--------------------------
+ Index Scan using storico_misure_idx on storico_misure
+(cost=3D0.00..2097.56 rows=3D547 width=3D21) (actual time=3D0.518..92.067
+rows=3D835 loops=3D1)
+   Index Cond: ((tag_id =3D 37423) AND (data_tag > '2004-05-03
+00:00:00'::timestamp without time zone) AND (data_tag < '2004-05-12
+00:00:00'::timestamp without time zone))
+ Total runtime: 93.459 ms
+(3 rows)
+
+
+I need the index on data_tag for other query ( last values on the last
+date ) .
+
+
+Regards=20
+
+Fabio=20
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 06:13:11 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 1BOYr2-0000AP-00; Fri, 14 May 2004 11:19:44 +0200
+From: "Fabio Panizzutti" 
+To: "'Manfred Koizar'" 
+Cc: 
+Subject: R: R: Query plan on identical tables differs . Why ?
+Date: Fri, 14 May 2004 11:22:44 +0200
+Message-ID: <001101c43995$03e8b830$3c02020a@ufficio>
+MIME-Version: 1.0
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+
+
+
+>>>> Index Scan using pk_storico_misure_2 on storico_misure 
+>>>>(cost=0.00..1984.64 rows=658 width=21) (actual 
+>>>time=723.441..1858.107 
+>>>>rows=835 loops=1)
+>>>>   Index Cond: ((data_tag > '2004-05-03 
+>>>00:00:00'::timestamp without 
+>>>>time zone) AND (data_tag < '2004-05-12 00:00:00'::timestamp without 
+>>>>time
+>>>>zone) AND (tag_id = 37423))
+>>>
+>>>Either most of the time is spent skipping index tuples in 
+>>>the data_tag range 2004-05-03 to 2004-05-12 which have 
+>>>tag_id <> 37423, or getting those 835 rows causes a lot of 
+>>>disk seeks.
+>>>
+>>>If the former is true, an index on (tag_id, data_tag) will help.
+>>>
+Is true , i recreate the indexes making an index on  (tag_id, data_tag)
+and works fine . 
+
+
+>>>In your first message you wrote:
+>>>>fsync = false
+>>>
+>>>Do this only if you don't care for your data.
+>>>
+
+I set it to false , for performance tests .I've a stored procedure that
+make about 2000 insert in 2 tables and 2000 delete in another and with
+fsync false perfomrmance are  2.000 -3.000 ms (stable) with fsync 3.000
+ms to 15.000 ms . I trust in my hardware an O.S so fsync setting is a
+big dubt for my production enviroment .
+
+Thanks a lot
+
+Bye 
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 06:55:55 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 14 May 2004 17:55:17 +0800 (WST)
+From: Christopher Kings-Lynne 
+To: Fabio Panizzutti 
+Cc: "'Manfred Koizar'" ,
+	
+Subject: Re: R: R: Query plan on identical tables differs . Why ?
+In-Reply-To: <001101c43995$03e8b830$3c02020a@ufficio>
+Message-ID: <20040514175425.S22343-100000@houston.familyhealth.com.au>
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+
+> I trust in my hardware an O.S so fsync setting is a
+> big dubt for my production enviroment .
+
+Then you are making a big mistake, loving your hardware more than your
+data...
+
+Chris
+
+
+
+From pgsql-admin-owner@postgresql.org  Fri May 14 07:15:39 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
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+	14 May 2004 22:15:09 +1200 (NZST)
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+	Fri, 14 May 2004 22:15:07 +1200 (NZST)
+Date: Fri, 14 May 2004 22:17:10 +1200
+From: Mark Kirkwood 
+Subject: Re: [PERFORM] Quad processor options - summary
+In-reply-to: <40A3EE5B.1050104@turtle-entertainment.de>
+To: Bjoern Metzdorf 
+Cc: James Thornton ,
+	pgsql-performance@postgresql.org, pgsql-admin@postgresql.org
+Message-id: <40A49CA6.1020500@paradise.net.nz>
+MIME-version: 1.0
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+References: 
+	<40A2A7FA.6060403@turtle-entertainment.de>
+	<40A3E250.2020204@jamesthornton.com>
+	<40A3EE5B.1050104@turtle-entertainment.de>
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+
+I would recommend trying out several stripe sizes, and making your own 
+measurements.
+
+A while ago I was involved in building a data warehouse system (Oracle, 
+DB2) and after several file and db benchmark exercises we used 256K 
+stripes, as these gave the best overall performance results for both 
+systems.
+
+I am not saying "1M is wrong", but I am saying "1M may not be right" :-)
+
+regards
+
+Mark
+
+Bjoern Metzdorf wrote:
+
+>
+> 1. Get many drives and stripe them into a RAID0 with a stripe width of 
+> 1MB. I am not quite sure if this stripe width is to be controlled at 
+> the application level (does postgres support this?) or if e.g. the 
+> "chunk size" of the linux software driver is meant. Normally a chunk 
+> size of 4KB is recommended, so 1MB sounds fairly large.
+>
+>
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 07:20:47 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 1BOZuO-0001K9-00; Fri, 14 May 2004 12:27:16 +0200
+From: "Fabio Panizzutti" 
+To: "'Christopher Kings-Lynne'" 
+Cc: 
+Subject: R: R: R: Query plan on identical tables differs . Why ?
+Date: Fri, 14 May 2004 12:30:16 +0200
+Message-ID: <001201c4399e$73469cc0$3c02020a@ufficio>
+MIME-Version: 1.0
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+	charset="iso-8859-1"
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+In-Reply-To: <20040514175425.S22343-100000@houston.familyhealth.com.au>
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+
+
+
+>>>-----Messaggio originale-----
+>>>Da: pgsql-performance-owner@postgresql.org=20
+>>>[mailto:pgsql-performance-owner@postgresql.org] Per conto di=20
+>>>Christopher Kings-Lynne
+>>>Inviato: venerd=EC 14 maggio 2004 11.55
+>>>A: Fabio Panizzutti
+>>>Cc: 'Manfred Koizar'; pgsql-performance@postgresql.org
+>>>Oggetto: Re: R: R: [PERFORM] Query plan on identical tables=20
+>>>differs . Why ?
+>>>
+>>>
+>>>> I trust in my hardware an O.S so fsync setting is a
+>>>> big dubt for my production enviroment .
+>>>
+>>>Then you are making a big mistake, loving your hardware more=20
+>>>than your data...
+>>>
+>>>Chris
+>>>
+
+
+I'm testing for better performance in insert/delete so i turn off fsync
+, i don't love hardware more than data , so i'll set fsync on in the
+production enviroment .
+Thanks a lot
+
+Best regards
+
+Fabio=20=20=20=20
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 15:12:28 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Fri, 14 May 2004 11:00:37 PDT
+Date: Fri, 14 May 2004 11:00:37 -0700 (PDT)
+From: Eduardo Almeida 
+Subject: TPCH 100GB - need some help
+To: pgsql-performance@postgresql.org
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/140
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+
+Hi folks,
+
+I need some help in a TPCH 100GB benchmark.
+
+I described our settings in:
+http://archives.postgresql.org/pgsql-performance/2004-04/msg00377.php
+
+Some queries are taking to long to finish (4, 8, 9,
+10, 19,20 and 22) and I need some help to increase the
+system performance.
+Here I put the query #19, the explain and the "top"
+for it. 
+This query is running since yesterday 10 AM.
+
+Query text is:
+
+select
+        sum(l_extendedprice* (1 - l_discount)) as
+revenue
+from
+        lineitem,
+        part
+where
+        (
+                p_partkey = l_partkey
+                and p_brand = 'Brand#32'
+                and p_container in ('SM CASE', 'SM
+BOX', 'SM PACK', 'SM PKG')
+                and l_quantity >= 2 and l_quantity <=
+2 + 10
+                and p_size between 1 and 5
+                and l_shipmode in ('AIR', 'AIR REG')
+                and l_shipinstruct = 'DELIVER IN
+PERSON'
+        )
+        or
+        (
+                p_partkey = l_partkey
+                and p_brand = 'Brand#42'
+                and p_container in ('MED BAG', 'MED
+BOX', 'MED PKG', 'MED PACK')
+                and l_quantity >= 11 and l_quantity <=
+11 + 10
+                and p_size between 1 and 10
+                and l_shipmode in ('AIR', 'AIR REG')
+                and l_shipinstruct = 'DELIVER IN
+PERSON'
+        )
+     or
+        (
+                p_partkey = l_partkey
+                and p_brand = 'Brand#54'
+                and p_container in ('LG CASE', 'LG
+BOX', 'LG PACK', 'LG PKG')
+                and l_quantity >= 27 and l_quantity <=
+27 + 10
+                and p_size between 1 and 15
+                and l_shipmode in ('AIR', 'AIR REG')
+                and l_shipinstruct = 'DELIVER IN
+PERSON'
+        );
+
+
+
+Tasks:  57 total,   2 running,  55 sleeping,   0
+stopped,   0 zombie
+Cpu(s):  16.5% user,   1.8% system,   0.0% nice, 
+59.2% idle,  22.5% IO-wait
+Mem:   4036184k total,  4025008k used,    11176k free,
+    4868k buffers
+Swap:  4088500k total,    13204k used,  4075296k free,
+ 3770208k cached
+
+  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM   
+TIME+  COMMAND
+28118 postgres  25   0  372m 354m 335m R 99.4  9.0  
+1724:45 postmaster
+
+
+ Aggregate 
+(cost=6825900228313539.00..6825900228313539.00 rows=1
+width=22)
+   ->  Nested Loop 
+(cost=887411.00..6825900228313538.00 rows=325
+width=22)
+         ->  Seq Scan on lineitem 
+(cost=0.00..21797716.88 rows=600037888 width=79)
+         ->  Materialize  (cost=887411.00..1263193.00
+rows=20000000 width=36)
+               ->  Seq Scan on part 
+(cost=0.00..711629.00 rows=20000000 width=36)
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+SBC Yahoo! - Internet access at a great low price.
+http://promo.yahoo.com/sbc/
+
+From pgsql-performance-owner@postgresql.org  Fri May 14 18:08:41 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+From: "Jaime Casanova" 
+To: pgsql-performance@postgresql.org
+Subject: numeric data types
+Date: Fri, 14 May 2004 21:08:19 +0000
+Mime-Version: 1.0
+Content-Type: text/plain; format=flowed
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+
+Hi all,
+
+i have a question, is there any advantages in using numeric(1) or numeric(2) 
+in place of smallint?
+is there any diff. in performance if i use smallint in place of integer?
+
+Thanx in advance,
+Jaime Casanova
+
+_________________________________________________________________
+Help STOP SPAM with the new MSN 8 and get 2 months FREE*  
+http://join.msn.com/?page=features/junkmail
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+
+From pgsql-performance-owner@postgresql.org  Fri May 14 15:26:17 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 44DC276AD7; Fri, 14 May 2004 14:25:56 -0400 (EDT)
+Subject: Re: TPCH 100GB - need some help
+From: Rod Taylor 
+To: Eduardo Almeida 
+Cc: Postgresql Performance 
+In-Reply-To: <20040514180037.8730.qmail@web60608.mail.yahoo.com>
+References: <20040514180037.8730.qmail@web60608.mail.yahoo.com>
+Content-Type: text/plain
+Message-Id: <1084570822.672.43.camel@jester>
+Mime-Version: 1.0
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+Date: Fri, 14 May 2004 17:40:23 -0400
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+
+On Fri, 2004-05-14 at 14:00, Eduardo Almeida wrote:
+> Hi folks,
+> 
+> I need some help in a TPCH 100GB benchmark.
+
+Performance with 7.5 is much improved over 7.4 for TPCH due to efforts
+of Tom Lane and OSDL. Give it a try with a recent snapshot of
+PostgreSQL.
+
+Otherwise, disable nested loops for that query. 
+
+        set enable_nestloop = off;
+
+
+
+From pgsql-performance-owner@postgresql.org  Sat May 15 01:03:47 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Sat, 15 May 2004 00:03:16 -0400 (EDT)
+To: "Jaime Casanova" 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: numeric data types 
+In-reply-to:  
+References: 
+Comments: In-reply-to "Jaime Casanova" 
+	message dated "Fri, 14 May 2004 21:08:19 -0000"
+Date: Sat, 15 May 2004 00:03:16 -0400
+Message-ID: <3209.1084593796@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+"Jaime Casanova"  writes:
+> i have a question, is there any advantages in using numeric(1) or numeric(2) 
+> in place of smallint?
+
+Performance-wise, smallint is an order of magnitude better.
+
+			regards, tom lane
+
+From pgsql-general-owner@postgresql.org  Sun May 16 14:21:36 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Sat, 15 May 2004 12:52:27 +0200
+From: share-postgres@think42.com
+To: pgsql-general@postgresql.org
+Subject: filesystem option tuning
+Message-ID: <20040515125227.A29574@p15097255.pureserver.info>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline
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+X-Spam-Level: 
+X-Archive-Number: 200405/482
+X-Sequence-Number: 60916
+
+Hi All,
+
+I have recently started evaluating Postgresql 7.4.2 to replace some *cough*
+more proprietary database systems... Thanks to the _excellent_ documentation
+(a point I cannot overemphasize) I was up and running in no time, and got a
+first test application running on the native C interface.
+
+There is just one point where I found the documentation lacking any
+description and practical hints (as opposed to all other topics), namely
+that of how to tune a setup for maximum performance regarding the layout of
+partitions on hard-disks and their mount options.
+
+I gather that the pg_xlog directory contains the transaction log and would
+benefit greatly from being put on a separate partition. I would then mount
+that partition with the noatime and forcedirectio options (on Solaris, the
+latter to circumvent the OS' buffer cache)? On the other hand the data
+partition should not be mounted with direct io, since Postgresql is
+documented as relying heavily on the OS' cache?
+
+Then I was wondering whether the fsync option refers only to the wal log (is
+that another name for the xlog, or is one a subset of the other?), or also
+to data write operations? With forcedirectio for the wal, do I still need
+fsync (or O_SYNC...) because otherwise I could corrupt the data?
+
+Are there any other directories that might benefit from being put on a
+dedicated disk, and with which mount options? Even without things like
+tablespaces there should be some headroom over having everything on one
+partition like in the default setup.
+
+What I should add is that reliability is a premium for us, we do not want to
+sacrifice integrity for speed, and that we are tuning for a high commit rate
+of small, simple transactions...
+
+I would be greatly thankful if somebody could give me some hints or pointers
+to further documentation as my search on the web did not show up much.
+
+Regards, Colin
+
+From pgsql-performance-owner@postgresql.org  Sat May 15 13:04:15 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+	Sat, 15 May 2004 12:00:33 -0400 (EDT)
+To: Eduardo Almeida 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: TPCH 100GB - need some help 
+In-reply-to: <20040514180037.8730.qmail@web60608.mail.yahoo.com> 
+References: <20040514180037.8730.qmail@web60608.mail.yahoo.com>
+Comments: In-reply-to Eduardo Almeida 
+	message dated "Fri, 14 May 2004 11:00:37 -0700"
+Date: Sat, 15 May 2004 12:00:33 -0400
+Message-ID: <7284.1084636833@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
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+X-Sequence-Number: 6975
+
+Eduardo Almeida  writes:
+> I need some help in a TPCH 100GB benchmark.
+> Here I put the query #19, the explain and the "top"
+> for it. 
+
+IIRC, this is one of the cases that inspired the work that's been done
+on the query optimizer for 7.5.  I don't think you will be able to get
+7.4 to generate a good plan for it (at least not without changing the
+query, which is against the TPC rules).  How do you feel about running
+CVS tip?
+
+BTW, are you aware that OSDL has already done a good deal of work with
+running TPC benchmarks for Postgres (and some other OS databases)?
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Sun May 16 14:13:20 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	by bob.samurai.com (Postfix) with ESMTP
+	id 51CC21E2B; Sat, 15 May 2004 22:28:03 -0400 (EDT)
+Subject: Re: numeric data types
+From: Neil Conway 
+To: Jaime Casanova 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: 
+References: 
+Content-Type: text/plain
+Message-Id: <1084674467.25578.115.camel@tokyo>
+Mime-Version: 1.0
+X-Mailer: Ximian Evolution 1.4.6 
+Date: Sat, 15 May 2004 22:27:47 -0400
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+
+On Fri, 2004-05-14 at 17:08, Jaime Casanova wrote:
+> is there any diff. in performance if i use smallint in place of integer?
+
+Assuming you steer clear of planner deficiencies, smallint should be
+slightly faster (since it consumes less disk space), but the performance
+difference should be very small. Also, alignment/padding considerations
+may mean that smallint doesn't actually save any space anyway.
+
+-Neil
+
+
+
+From pgsql-general-owner@postgresql.org  Mon May 17 14:17:34 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
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+Message-ID: <40A8F0B6.6060703@archonet.com>
+Date: Mon, 17 May 2004 18:04:54 +0100
+From: Richard Huxton 
+User-Agent: Mozilla Thunderbird 0.6 (X11/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: share-postgres@think42.com
+Cc: pgsql-general@postgresql.org
+Subject: Re: filesystem option tuning
+References: <20040515125227.A29574@p15097255.pureserver.info>
+In-Reply-To: <20040515125227.A29574@p15097255.pureserver.info>
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+X-Sequence-Number: 60957
+
+share-postgres@think42.com wrote:
+> Hi All,
+> 
+> I have recently started evaluating Postgresql 7.4.2 to replace some *cough*
+> more proprietary database systems... Thanks to the _excellent_ documentation
+> (a point I cannot overemphasize) I was up and running in no time, and got a
+> first test application running on the native C interface.
+
+In no official capacity whatsoever, welcome aboard.
+
+> There is just one point where I found the documentation lacking any
+> description and practical hints (as opposed to all other topics), namely
+> that of how to tune a setup for maximum performance regarding the layout of
+> partitions on hard-disks and their mount options.
+
+I'm not a Sun user, so I can't give any OS-specific notes, but in general:
+  - Don't bypass the filesystem, but feel free to tinker with mount 
+options if you think it will help
+  - If you can put WAL on separate disk(s), all the better.
+  - The general opinion seems to be RAID5 is slower than RAID10 unless 
+you have a lot of disks
+  - Battery-backed write-cache for your SCSI controller can be a big 
+performance win
+  - Tablespaces _should_ be available in the next release of PG, we'll 
+know for sure soon. That might make life simpler for you if you do want 
+to spread your database around by hand,
+
+> What I should add is that reliability is a premium for us, we do not want to
+> sacrifice integrity for speed, and that we are tuning for a high commit rate
+> of small, simple transactions...
+
+Make sure the WAL is on fast disks I'd suggest. At a guess that'll be 
+your bottleneck.
+
+For more info, your best bet is to check the archives on the 
+plpgsql-performance list, and then post there. People will probably want 
+to know more about your database size/number of concurrent 
+transactions/disk systems etc.
+
+HTH
+-- 
+   Richard Huxton
+   Archonet Ltd
+
+From pgsql-admin-owner@postgresql.org  Mon May 17 20:10:42 2004
+X-Original-To: pgsql-admin-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <64EDC403A1417B4299488BAE87CA7CBF01CD0E15@maricopa_xcng0>
+From: Duane Lee - EGOVX 
+To: "PG General (E-mail)" ,
+	"PGADMIN (E-mail)" ,
+	"PSQL Performance (E-mail)" 
+Subject: Hardware Platform
+Date: Mon, 17 May 2004 16:08:34 -0700
+MIME-Version: 1.0
+X-Mailer: Internet Mail Service (5.5.2657.72)
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+
+This message is in MIME format. Since your mail reader does not understand
+this format, some or all of this message may not be legible.
+
+------_=_NextPart_001_01C43C63.E0BF5180
+Content-Type: text/plain;
+	charset="iso-8859-1"
+
+I'm working on a project using PostgreSQL as our database designing a budget
+system.  We are still in the design and testing phases but I thought I would
+ask advice about a platform to host this system.
+
+We aren't a large system, probably no more than 50-75 users at any one time.
+>From a data standpoint I can't guess at the number of gigabytes but suffice
+to say it is not going to be that large.  Our biggest table will probably
+hold about 1 million rows and is about 120 bytes (closer to about 100).
+
+Dell and HP servers are being mentioned but we currently have no preference.
+
+Any help you could provide will be appreciated.
+
+Thanks,
+Duane
+
+P.S. I've only just begun using PostgreSQL after having used (and still
+using) DB2 on a mainframe for the past 14 years.  My experience with
+Unix/Linux is limited to some community college classes I've taken but we do
+have a couple of experienced Linux sysadmins on our team.  I tell you this
+because my "ignorance" will probably show more than once in my inquiries.
+
+
+------_=_NextPart_001_01C43C63.E0BF5180
+Content-Type: text/html;
+	charset="iso-8859-1"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+Hardware Platform
+
+
+
+
I'm working on a project using PostgreSQL as our database=
+ designing a budget system.  We are still in the design and testing ph=
+ases but I thought I would ask advice about a platform to host this system.=
+

+
+
We aren't a large system, probably no more than 50-75 use=
+rs at any one time.  From a data standpoint I can't guess at the numbe=
+r of gigabytes but suffice to say it is not going to be that large.  O=
+ur biggest table will probably hold about 1 million rows and is about 120 b=
+ytes (closer to about 100).

+
+
Dell and HP servers are being mentioned but we currently =
+have no preference.
+

+
+
Any help you could provide will be appreciated.
+

+
+
Thanks,
+
Duane
+

+
+
P.S. I've only just begun using PostgreSQL after having u=
+sed (and still using) DB2 on a mainframe for the past 14 years.  My ex=
+perience with Unix/Linux is limited to some community college classes I've =
+taken but we do have a couple of experienced Linux sysadmins on our team.&n=
+bsp; I tell you this because my "ignorance" will probably show mo=
+re than once in my inquiries.

+
+
+
+------_=_NextPart_001_01C43C63.E0BF5180--
+
+From pgsql-performance-owner@postgresql.org  Tue May 18 09:51:49 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 18 May 2004 05:49:12 PDT
+Date: Tue, 18 May 2004 05:49:12 -0700 (PDT)
+From: Eduardo Almeida 
+Subject: Re: TPCH 100GB - need some help 
+To: Tom Lane 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: <7284.1084636833@sss.pgh.pa.us>
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
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+X-Archive-Number: 200405/147
+X-Sequence-Number: 6978
+
+Mr. Tom Lane
+
+
+--- Tom Lane  wrote:
+> Eduardo Almeida  writes:
+> > I need some help in a TPCH 100GB benchmark.
+> > Here I put the query #19, the explain and the
+> "top"
+> > for it. 
+> 
+> IIRC, this is one of the cases that inspired the
+> work that's been done
+> on the query optimizer for 7.5.  I don't think you
+> will be able to get
+> 7.4 to generate a good plan for it (at least not
+> without changing the
+> query, which is against the TPC rules).  How do you
+> feel about running
+> CVS tip?
+
+We are testing the postgre 7.4.2 to show results to
+some projects here in Brazil. We are near the deadline
+for these projects and we need to show results with a
+stable version.
+
+ASAP I want and I will help the PG community testing
+the CVS with VLDB.
+
+> 
+> BTW, are you aware that OSDL has already done a good
+> deal of work with
+> running TPC benchmarks for Postgres (and some other
+> OS databases)?
+
+No! Now I'm considering the use of OSDL because of
+query rewrite. Yesterday the query #19 that I describe
+runs in the OSDL way.
+
+We found some interesting patterns in queries that
+take to long to finish in the 100 GB test.
+�	Sub-queries inside other sub-queries (Q20 and Q22);
+�	Exists and Not exists selection (Q4, Q21 and Q22);
+�	Aggregations with in-line views, that is queries
+inside FROM clause (Q7, Q8, Q9 and Q22);
+
+In fact these queries were aborted by timeout 
+statement_timeout = 25000000
+
+I took off the timeout to Q20 and it finished in
+23:53:49 hs.
+
+tks a lot,
+Eduardo
+
+ps. sorry about my english
+
+> 
+> 			regards, tom lane
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+SBC Yahoo! - Internet access at a great low price.
+http://promo.yahoo.com/sbc/
+
+From pgsql-performance-owner@postgresql.org  Tue May 18 15:43:58 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1
+Date: Tue, 18 May 2004 14:12:14 -0400
+To: pgsql-performance@postgresql.org
+From: Doug Y 
+Subject: Interpreting vmstat
+Mime-Version: 1.0
+Content-Type: text/plain; charset="us-ascii"; format=flowed
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/148
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+
+Hello,
+  (note best viewed in fixed-width font)
+
+   I'm still trying to find where my performance bottle neck is...
+I have 4G ram, PG 7.3.4
+shared_buffers = 75000
+effective_cache_size = 75000
+
+Run a query I've been having trouble with and watch the output of vmstat 
+(linux):
+
+$ vmstat 1
+    procs                      memory    swap          io     system 
+  cpu
+  r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us 
+sy  id
+  0  0  0    148   8732 193652 
+2786668   0   0     0     0  292   151   0   2  98
+  2  0  2    148   7040 193652 
+2786668   0   0     0   208  459   697  45  10  45
+  0  0  0    148   9028 193652 
+2786684   0   0    16   644  318   613  25   4  71
+  1  0  0    148   5092 193676 
+2780196   0   0    12   184  441   491  37   5  58
+  0  1  0    148   5212 193684 
+2772512   0   0   112  9740  682  1063  45  12  43
+  1  0  0    148   5444 193684 
+2771584   0   0   120  4216  464  1303  44   3  52
+  1  0  0    148  12232 193660 
+2771620   0   0   244   628  340   681  43  20  38
+  1  0  0    148  12168 193664 
+2771832   0   0   196   552  332   956  42   2  56
+  1  0  0    148  12080 193664 
+2772248   0   0   272   204  371   201  40   1  59
+  1  1  0    148  12024 193664 
+2772624   0   0   368     0  259   127  42   3  55
+
+Thats the first 10 lines or so... the query takes 60 seconds to run.
+
+I'm confused on the bo & bi parts of the io:
+    IO
+        bi: Blocks sent to a block device (blocks/s).
+        bo: Blocks received from a block device (blocks/s).
+
+yet it seems to be opposite of that... bi only increases when doing a 
+largish query, while bo also goes up, I typically see periodic bo numbers 
+in the low 100's, which I'd guess are log writes.
+
+I would think that my entire DB should end up cached since a raw pg_dump 
+file is about 1G in size, yet my performance doesn't indicate that that is 
+the case... running the same query a few minutes later, I'm not seeing a 
+significant performance improvement.
+
+Here's a sample from iostat while the query is running:
+
+$ iostat -x -d 1
+
+Device:  rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s avgrq-sz 
+avgqu-sz   await  svctm  %util
+sda        0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949552.96    0.00   0.00 100.00
+sda1       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949662.96    0.00   0.00 100.00
+sda2       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949642.96    0.00   0.00 100.00
+sdb        0.00 428.00  0.00 116.00    0.00 
+4368.00    37.66  2844.40  296.55  86.21 100.00
+sdb1       0.00 428.00  0.00 116.00    0.00 
+4368.00    37.66  6874.40  296.55  86.21 100.00
+
+Device:  rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s avgrq-sz 
+avgqu-sz   await  svctm  %util
+sda        0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949552.96    0.00   0.00 100.00
+sda1       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949662.96    0.00   0.00 100.00
+sda2       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949642.96    0.00   0.00 100.00
+sdb        4.00 182.00  6.00 77.00   80.00 
+2072.00    25.93  2814.50   54.22 120.48 100.00
+sdb1       4.00 182.00  6.00 77.00   80.00 
+2072.00    25.93  6844.50   54.22 120.48 100.00
+
+Device:  rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s avgrq-sz 
+avgqu-sz   await  svctm  %util
+sda        0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949552.96    0.00   0.00 100.00
+sda1       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949662.96    0.00   0.00 100.00
+sda2       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949642.96    0.00   0.00 100.00
+sdb        0.00  43.00  0.00 
+11.00    0.00  432.00    39.27  2810.40   36.36 909.09 100.00
+sdb1       0.00  43.00  0.00 
+11.00    0.00  432.00    39.27  6840.40   36.36 909.09 100.00
+
+Device:  rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s avgrq-sz 
+avgqu-sz   await  svctm  %util
+sda        0.00  15.84  0.00 17.82    0.00  269.31    15.11 
+42524309.47   44.44 561.11 100.00
+sda1       0.00  15.84  0.00 17.82    0.00  269.31    15.11 
+42524419.47   44.44 561.11 100.00
+sda2       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42524398.67    0.00   0.00 100.00
+sdb        0.99 222.77  0.99 114.85   15.84 
+2700.99    23.45  2814.16   35.90  86.32 100.00
+sdb1       0.99 222.77  0.99 114.85   15.84 
+2700.99    23.45  6844.16   35.90  86.32 100.00
+
+Device:  rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s avgrq-sz 
+avgqu-sz   await  svctm  %util
+sda        0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949551.76    0.00   0.00 101.00
+sda1       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949662.86    0.00   0.00 101.00
+sda2       0.00   0.00  0.00  0.00    0.00    0.00     0.00 
+42949642.66    0.00   0.00 101.00
+sdb        1.00  91.00  1.00 
+28.00   16.00  960.00    33.66  2838.40   10.34 348.28 101.00
+sdb1       1.00  91.00  1.00 
+28.00   16.00  960.00    33.66  6908.70   10.34 348.28 101.00
+
+The DB files and logs are on sdb1.
+
+Can someone point me in the direction of some documentation on how to 
+interpret these numbers?
+
+Also, I've tried to figure out what's getting cached by PostgreSQL by 
+looking at pg_statio_all_tables. What kind of ratio should I be seeing for 
+heap_blks_read / heap_blks_hit ?
+
+Thanks.
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 18 18:30:36 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Tue, 18 May 2004 14:13:21 PDT
+Date: Tue, 18 May 2004 14:13:21 -0700 (PDT)
+From: Litao Wu 
+Subject: where to find out when a table was last analyzed?
+To: pgsql-performance@postgresql.org
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
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+
+All,
+
+Does PG store when a table was last analyzed?
+
+Thanks,
+
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+SBC Yahoo! - Internet access at a great low price.
+http://promo.yahoo.com/sbc/
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 00:20:30 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for pgsql-performance@postgresql.org; Wed, 19 May 2004 02:51:33 GMT
+From: Joseph Shraibman 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: Using LIKE expression problem..
+Date: Tue, 18 May 2004 22:51:30 -0400
+Organization: Hub.Org Networking Services
+Lines: 63
+Message-ID: <40AACBB2.6060001@selectacast.net>
+References: <40A1D94E.9030605@familyhealth.com.au>
+	<200405120804.i4C84gh9004444@mail.census.gov.ph>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii; format=flowed
+Content-Transfer-Encoding: 7bit
+X-Complaints-To: usenet@news.hub.org
+To: "Michael Ryan S. Puncia" 
+User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040514
+X-Accept-Language: en-us, en
+In-Reply-To: <200405120804.i4C84gh9004444@mail.census.gov.ph>
+To: pgsql-performance@postgresql.org
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+
+Use the text_pattern_ops operator when creating the index, see:
+http://www.postgresql.org/docs/7.4/static/indexes-opclass.html
+
+Michael Ryan S. Puncia wrote:
+> Sorry .. I am a newbie and I don't know :( 
+> How can I know that I am in C locale ?
+> How can I change my database to use C locale?
+> 
+> 
+> 
+> -----Original Message-----
+> From: pgsql-performance-owner@postgresql.org
+> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+> Kings-Lynne
+> Sent: Wednesday, May 12, 2004 3:59 PM
+> To: Michael Ryan S. Puncia
+> Cc: pgsql-performance@postgresql.org
+> Subject: Re: [PERFORM] Using LIKE expression problem..
+> 
+> Are you in a non-C locale?
+> 
+> Chris
+> 
+> Michael Ryan S. Puncia wrote:
+> 
+> 
+>>Yes , I already do that but the same result .. LIKE uses seq scan
+>>
+>>-----Original Message-----
+>>From: pgsql-performance-owner@postgresql.org
+>>[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Christopher
+>>Kings-Lynne
+>>Sent: Wednesday, May 12, 2004 2:48 PM
+>>To: Michael Ryan S. Puncia
+>>Cc: pgsql-performance@postgresql.org
+>>Subject: Re: [PERFORM] Using LIKE expression problem..
+>>
+>>
+>>
+>>>In the query plan ..it uses seq scan rather than index scan .. why ? I 
+>>>have index on lastname, firtname.
+>>
+>>
+>>Have you run VACUUM ANALYZE; on the table recently?
+>>
+>>Chris
+>>
+>>
+>>---------------------------(end of broadcast)---------------------------
+>>TIP 7: don't forget to increase your free space map settings
+>>
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 5: Have you checked our extensive FAQ?
+> 
+>                http://www.postgresql.org/docs/faqs/FAQ.html
+> 
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 4: Don't 'kill -9' the postmaster
+> 
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 00:39:11 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40AAD6B1.2030901@outputservices.com>
+Date: Tue, 18 May 2004 21:38:25 -0600
+From: Marty Scholes 
+User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:0.9.9) Gecko/20020517
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Subject: Re: Quad processor options
+Content-Type: text/plain; charset=us-ascii; format=flowed
+Content-Transfer-Encoding: 7bit
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/151
+X-Sequence-Number: 6982
+
+After reading the replies to this, it is clear that this is a 
+Lintel-centric question, but I will throw in my experience.
+
+ > I am curious if there are any real life production
+ > quad processor setups running postgresql out there.
+
+Yes.  We are running a 24/7 operation on a quad CPU Sun V880.
+
+ > Since postgresql lacks a proper replication/cluster
+ > solution, we have to buy a bigger machine.
+
+This was a compelling reason for us to stick with SPARC and avoid 
+Intel/AMD when picking a DB server.  We moved off of an IBM mainframe in 
+1993 to Sun gear and never looked back.  We can upgrade to our heart's 
+content with minimal disruption and are only on our third box in 11 
+years with plenty of life left in our current one.
+
+ > Right now we are running on a dual 2.4 Xeon, 3 GB Ram
+ > and U160 SCSI hardware-raid 10.
+
+A couple people mentioned hardware RAID, which I completely agree with. 
+  I prefer an external box with a SCSI or FC connector.  There are no 
+driver issues that way.  We boot from our arrays.
+
+The Nexsan ATABoy2 is a nice blend of performance, reliability and cost. 
+  Some of these with 1TB and 2TB of space were recently spotted on ebay 
+for under $5k.  We run a VERY random i/o mix on ours and it will 
+consistently sustain 15 MB/s in blended read and write i/o, sustaining 
+well over 1200 io/s.  These are IDE drives, so they fail more often than 
+SCSI, so run RAID1 or RAID5.  The cache on these pretty much eliminates 
+the RAID5 penalties.
+
+ > The 30k+ setups from Dell etc. don't fit our budget.
+
+For that kind of money you could get a lower end Sun box (or IBM RS/6000 
+I would imagine) and give yourself an astounding amount of headroom for 
+future growth.
+
+Sincerely,
+Marty
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 28 20:57:07 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Wed, 19 May 2004 09:32:39 +0200
+From: share-postgres@think42.com
+To: Richard Huxton ,
+	pgsql-performance@postgresql.org
+Subject: Re: filesystem option tuning
+Message-ID: <20040519093239.A26016@p15097255.pureserver.info>
+References: <20040515125227.A29574@p15097255.pureserver.info>
+	<40A8F0B6.6060703@archonet.com>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline
+User-Agent: Mutt/1.3.16i
+In-Reply-To: <40A8F0B6.6060703@archonet.com>;
+	from dev@archonet.com on Mon, May 17, 2004 at 06:04:54PM +0100
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/223
+X-Sequence-Number: 7054
+
+Hi!
+
+On Mon, May 17, 2004 at 06:04:54PM +0100, Richard Huxton wrote:
+> share-postgres@think42.com wrote:
+> > [...]
+> 
+> In no official capacity whatsoever, welcome aboard.
+
+Thanks ;-)
+
+> > There is just one point where I found the documentation lacking any
+> > description and practical hints (as opposed to all other topics), namely
+> > that of how to tune a setup for maximum performance regarding the layout of
+> > partitions on hard-disks and their mount options.
+> 
+> I'm not a Sun user, so I can't give any OS-specific notes, but in general:
+>   - Don't bypass the filesystem, but feel free to tinker with mount 
+> options if you think it will help
+
+Right, raw partitions are too low-level for me these days anyhow...
+I assume that all postgres partitions can be mounted with noatime?
+
+>   - If you can put WAL on separate disk(s), all the better.
+
+Does that mean only the xlog, or also the clog? As far as I understand, the
+clog contains some meta-information on the xlog, so presumably it is flushed
+to disc synchronously together with the xlog? That would mean that they each
+need a separate disk to prevent one disk having to seek too often...?
+
+>   - Battery-backed write-cache for your SCSI controller can be a big 
+> performance win
+
+I probably won't be able to get such a setup for this project; that's why I
+am bothering about which disk will be seeking how often.
+
+>   - Tablespaces _should_ be available in the next release of PG, we'll 
+> know for sure soon. That might make life simpler for you if you do want 
+> to spread your database around by hand,
+
+Ok, I think tablespaces are not the important thing - at least for this
+project of ours.
+
+> > What I should add is that reliability is a premium for us, we do not want to
+> > sacrifice integrity for speed, and that we are tuning for a high commit rate
+> > of small, simple transactions...
+> 
+> Make sure the WAL is on fast disks I'd suggest. At a guess that'll be 
+> your bottleneck.
+> 
+> For more info, your best bet is to check the archives on the 
+> plpgsql-performance list, and then post there. People will probably want 
+> to know more about your database size/number of concurrent 
+> transactions/disk systems etc.
+
+Here goes ... we are talking about a database cluster with two tables where
+things are happening, one is a kind of log that is simply "appended" to and
+will expect to reach a size of several million entries in the time window
+that is kept, the other is a persistent backing of application data that
+will mostly see read-modify-writes of single records. Two writers to the
+history, one writer to the data table. The volume of data is not very high
+and RAM is enough...
+
+If any more information is required feel free to ask - I would really
+appreciate getting this disk layout sorted out.
+
+Thanks,
+Colin
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 04:31:19 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	with ESMTP id 86904-02
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+	for ;
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+	for ; Wed, 19 May 2004 15:24:08 +0800
+Message-Id: <200405190724.i4J7NuPW030497@mail.census.gov.ph>
+From: "Michael Ryan S. Puncia" 
+To: 
+Subject: DB Design
+Date: Wed, 19 May 2004 15:37:06 +0800
+MIME-Version: 1.0
+Content-Type: multipart/alternative;
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+
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+
+------=_NextPart_000_0000_01C43DB7.27CE7D90
+Content-Type: text/plain;
+	charset="us-ascii"
+Content-Transfer-Encoding: 7bit
+
+Hi Guys,
+
+   
+
+      My question is .. which is better design
+
+ 
+
+1.	Single Table with 50 million records or
+2.	Multiple Table using inheritance to the parents table
+
+ 
+
+ 
+
+I will use this only for query purpose ..
+
+ 
+
+Thanks ..
+
+ 
+
+ 
+
+
+------=_NextPart_000_0000_01C43DB7.27CE7D90
+Content-Type: text/html;
+	charset="us-ascii"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+
+
+
+
+
+
+

+
+
Hi Guys,

+
+
   

+
+
      My question is .. which i=
+s better design

+
+
 

+
+
    
+ 
  1. Single Table with 50 mill=
+ion
+     records or
    2. 
+ 
  2. Multiple Table using
+     inheritance to the parents table
    3. 
+

+
+
 

+
+
 

+
+
I will use this only for query purpose ..

+
+
 

+
+
Thanks ..

+
+
 

+
+
 

+
+

+
+
+
+
+
+------=_NextPart_000_0000_01C43DB7.27CE7D90--
+
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 08:22:33 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+Received: from lamb.mcmillan.net.nz (218-101-14-65.paradise.net.nz
+	[218.101.14.65])
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+	by lamb.mcmillan.net.nz (Postfix) with ESMTP
+	id AB527AD98585; Wed, 19 May 2004 23:21:22 +1200 (NZST)
+Subject: Re: DB Design
+From: Andrew McMillan 
+To: "Michael Ryan S. Puncia" 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: <200405190724.i4J7NuPW030497@mail.census.gov.ph>
+References: <200405190724.i4J7NuPW030497@mail.census.gov.ph>
+Content-Type: text/plain
+Message-Id: <1084965682.10589.52.camel@lamb.mcmillan.net.nz>
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+Date: Wed, 19 May 2004 23:21:22 +1200
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+X-Sequence-Number: 6984
+
+On Wed, 2004-05-19 at 15:37 +0800, Michael Ryan S. Puncia wrote:
+> Hi Guys,
+> 
+>    
+> 
+>       My question is .. which is better design
+> 
+>  
+> 
+>      1. Single Table with 50 million records or
+>      2. Multiple Table using inheritance to the parents table
+
+It's not that simple.
+
+Given your e-mail address I assume you want to store Philippines Census
+data in such a table, but does Census data fit well in a single flat
+table structure?  Not from what I have seen here in NZ, but perhaps
+Census is simpler there.
+
+So to know what the best answer to that question is, people here will
+surely need more and better information from you about database schema,
+record size, indexing and query characteristics, and so on.
+
+
+> I will use this only for query purpose ..
+
+Then you may quite possibly want to consider a different database.
+Particularly if it is single-user query purposes.
+
+For example, there are some SQL databases that would load the entire
+database into RAM from static files, and then allow query against this.
+This can obviously give huge performance improvements in situations
+where volatility is not a problem.
+
+Cheers,
+					Andrew.
+
+-------------------------------------------------------------------------
+Andrew @ Catalyst .Net .NZ  Ltd,  PO Box 11-053,  Manners St,  Wellington
+WEB: http://catalyst.net.nz/             PHYS: Level 2, 150-154 Willis St
+DDI: +64(4)916-7201       MOB: +64(21)635-694      OFFICE: +64(4)499-2267
+                       Do not overtax your powers.
+-------------------------------------------------------------------------
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 16:51:02 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Wed, 19 May 2004 16:49:42 -0300 (ADT)
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+	for pgsql-performance@postgresql.org; Wed, 19 May 2004 19:26:29 GMT
+From: Joseph Shraibman 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: shared buffer size on linux
+Date: Wed, 19 May 2004 15:26:31 -0400
+Organization: Hub.Org Networking Services
+Lines: 3
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+
+See http://kerneltrap.org/node/view/3148, about 40% down, under the 
+header "2.6 -aa patchset, object-based reverse mapping".  Does this mean 
+that the more shared memory the bigger the potential for a swap storm?
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 17:07:26 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for pgsql-performance@postgresql.org; Thu, 20 May 2004 00:07:05 +0400
+Date: Thu, 20 May 2004 00:07:57 +0400
+From: Eugeny Balakhonov 
+Reply-To: Eugeny Balakhonov 
+X-Priority: 3 (Normal)
+Message-ID: <1117434122.20040520000757@mail.ru>
+To: pgsql-performance@postgresql.org
+Subject: PostgreSQL performance in simple queries
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
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+
+Hello for all!
+
+I have PostgreSQL 7.4 under last version of Cygwin and have some
+problems with performance :( It is very strange...  I don't remember
+this problem on previous version Cygwin and PostgreSQL 7.3
+
+I have only two simple tables:
+
+CREATE TABLE public.files_t
+(
+  id int8 NOT NULL,
+  parent int8,
+  size int8 NOT NULL,
+  dir bool NOT NULL DEFAULT false,
+  ctime timestamp NOT NULL,
+  ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+  name text NOT NULL,
+  access varchar(10) NOT NULL,
+  host int4 NOT NULL,
+  uname text NOT NULL,
+  CONSTRAINT pk_files_k PRIMARY KEY (id),
+  CONSTRAINT fk_files_k FOREIGN KEY (parent) REFERENCES public.files_t (id) ON UPDATE CASCADE ON DELETE CASCADE,
+  CONSTRAINT fk_hosts_k FOREIGN KEY (host) REFERENCES public.hosts_t (id) ON UPDATE CASCADE ON DELETE CASCADE
+) WITH OIDS;
+
+and
+
+CREATE TABLE public.hosts_t
+(
+  id int4 NOT NULL,
+  ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+  utime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+  name text NOT NULL,
+  address inet NOT NULL,
+  CONSTRAINT pk_hosts_k PRIMARY KEY (id)
+) WITH OIDS;
+
+Table files_t has 249259 records and table hosts_t has only 59 records.
+
+I tries to run simple query:
+
+select * from files_t where parent = 3333
+
+This query works 0.256 seconds! It is very big time for this small
+table!
+I have index for field "parent":
+
+CREATE INDEX files_parent_idx
+  ON public.files_t
+  USING btree
+  (parent);
+
+But if I tries to see query plan then I see following text:
+
+Seq Scan on files_t (cost=0.00..6103.89 rows=54 width=102)
+ Filter: (parent = 3333)
+
+PostgreSQL do not uses index files_parent_idx!
+
+I have enabled all options of "QUERY TUNING" in postgresql.conf, I
+have increased memory sizes for PostgreSQL:
+
+shared_buffers = 2000           # min 16, at least max_connections*2, 8KB each
+sort_mem = 32768                # min 64, size in KB
+vacuum_mem = 65536              # min 1024, size in KB
+fsync = false                   # turns forced synchronization on or off
+checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
+enable_hashagg = true
+enable_hashjoin = true
+enable_indexscan = true
+enable_mergejoin = true
+enable_nestloop = true
+enable_seqscan = true
+enable_sort = true
+enable_tidscan = true
+geqo = true
+geqo_threshold = 22
+geqo_effort = 1
+geqo_generations = 0
+geqo_pool_size = 0              # default based on tables in statement,
+                                # range 128-1024
+geqo_selection_bias = 2.0       # range 1.5-2.0
+stats_start_collector = true
+stats_command_string = true
+stats_block_level = true
+stats_row_level = true
+stats_reset_on_server_start = false
+
+
+Please help me!
+My database has a very small size (only 249259 records) but it works
+very slowly :(
+
+Best regards
+Eugeny
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 17:23:59 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ; Wed, 19 May 2004 21:15:59 +0100
+From: "Gary Doades" 
+To: pgsql-performance@postgresql.org
+Date: Wed, 19 May 2004 21:23:47 +0100
+MIME-Version: 1.0
+Subject: Re: PostgreSQL performance in simple queries
+Message-ID: <40ABD063.5457.AA3927B@localhost>
+In-reply-to: <1117434122.20040520000757@mail.ru>
+X-mailer: Pegasus Mail for Windows (v4.12a)
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+--Alt-Boundary-1301.178492027
+Content-type: text/plain; charset=US-ASCII
+Content-transfer-encoding: 7BIT
+Content-description: Mail message body
+
+Try using 
+
+select * from files_t where parent = 3333::int8
+
+You have declared parent as int8, but the query will assume int4 for "3333" and may not 
+use the index.
+
+Also make sure you have ANALYZEd this table.
+
+Regards,
+Gary.
+
+On 20 May 2004 at 0:07, Eugeny Balakhonov wrote:
+
+> Hello for all!
+> 
+> I have PostgreSQL 7.4 under last version of Cygwin and have some
+> problems with performance :( It is very strange...  I don't remember
+> this problem on previous version Cygwin and PostgreSQL 7.3
+> 
+> I have only two simple tables:
+> 
+> CREATE TABLE public.files_t
+> (
+>   id int8 NOT NULL,
+>   parent int8,
+>   size int8 NOT NULL,
+>   dir bool NOT NULL DEFAULT false,
+>   ctime timestamp NOT NULL,
+>   ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+>   name text NOT NULL,
+>   access varchar(10) NOT NULL,
+>   host int4 NOT NULL,
+>   uname text NOT NULL,
+>   CONSTRAINT pk_files_k PRIMARY KEY (id),
+>   CONSTRAINT fk_files_k FOREIGN KEY (parent) REFERENCES public.files_t (id) ON UPDATE CASCADE ON DELETE CASCADE,
+>   CONSTRAINT fk_hosts_k FOREIGN KEY (host) REFERENCES public.hosts_t (id) ON UPDATE CASCADE ON DELETE CASCADE
+> ) WITH OIDS;
+> 
+> and
+> 
+> CREATE TABLE public.hosts_t
+> (
+>   id int4 NOT NULL,
+>   ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+>   utime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,
+>   name text NOT NULL,
+>   address inet NOT NULL,
+>   CONSTRAINT pk_hosts_k PRIMARY KEY (id)
+> ) WITH OIDS;
+> 
+> Table files_t has 249259 records and table hosts_t has only 59 records.
+> 
+> I tries to run simple query:
+> 
+> select * from files_t where parent = 3333
+> 
+> This query works 0.256 seconds! It is very big time for this small
+> table!
+> I have index for field "parent":
+> 
+> CREATE INDEX files_parent_idx
+>   ON public.files_t
+>   USING btree
+>   (parent);
+> 
+> But if I tries to see query plan then I see following text:
+> 
+> Seq Scan on files_t (cost=0.00..6103.89 rows=54 width=102)
+>  Filter: (parent = 3333)
+> 
+> PostgreSQL do not uses index files_parent_idx!
+> 
+> I have enabled all options of "QUERY TUNING" in postgresql.conf, I
+> have increased memory sizes for PostgreSQL:
+> 
+> shared_buffers = 2000           # min 16, at least max_connections*2, 8KB each
+> sort_mem = 32768                # min 64, size in KB
+> vacuum_mem = 65536              # min 1024, size in KB
+> fsync = false                   # turns forced synchronization on or off
+> checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
+> enable_hashagg = true
+> enable_hashjoin = true
+> enable_indexscan = true
+> enable_mergejoin = true
+> enable_nestloop = true
+> enable_seqscan = true
+> enable_sort = true
+> enable_tidscan = true
+> geqo = true
+> geqo_threshold = 22
+> geqo_effort = 1
+> geqo_generations = 0
+> geqo_pool_size = 0              # default based on tables in statement,
+>                                 # range 128-1024
+> geqo_selection_bias = 2.0       # range 1.5-2.0
+> stats_start_collector = true
+> stats_command_string = true
+> stats_block_level = true
+> stats_row_level = true
+> stats_reset_on_server_start = false
+> 
+> 
+> Please help me!
+> My database has a very small size (only 249259 records) but it works
+> very slowly :(
+> 
+> Best regards
+> Eugeny
+> 
+> 
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 3: if posting/reading through Usenet, please send an appropriate
+>       subscribe-nomail command to majordomo@postgresql.org so that your
+>       message can get through to the mailing list cleanly
+
+
+
+--Alt-Boundary-1301.178492027
+Content-type: text/html; charset=US-ASCII
+Content-transfer-encoding: 7BIT
+Content-description: Mail message body
+
+
+
+
+
+
+
Try using 

+


+

+
select * from files_t where parent = 3333::int8

+


+

+
You have declared parent as int8, but the query will assume int4 for "3333" and may not 
+use the index.

+


+

+
Also make sure you have ANALYZEd this table.

+


+

+
Regards,

+
Gary.

+


+

+
On 20 May 2004 at 0:07, Eugeny Balakhonov wrote:

+


+

+
> Hello for all!

+
> 

+
> I have PostgreSQL 7.4 under last version of Cygwin and have some

+
> problems with performance :( It is very strange...  I don't remember

+
> this problem on previous version Cygwin and PostgreSQL 7.3

+
> 

+
> I have only two simple tables:

+
> 

+
> CREATE TABLE public.files_t

+
> (

+
>   id int8 NOT NULL,

+
>   parent int8,

+
>   size int8 NOT NULL,

+
>   dir bool NOT NULL DEFAULT false,

+
>   ctime timestamp NOT NULL,

+
>   ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,

+
>   name text NOT NULL,

+
>   access varchar(10) NOT NULL,

+
>   host int4 NOT NULL,

+
>   uname text NOT NULL,

+
>   CONSTRAINT pk_files_k PRIMARY KEY (id),

+
>   CONSTRAINT fk_files_k FOREIGN KEY (parent) REFERENCES public.files_t (id) 
+ON UPDATE CASCADE ON DELETE CASCADE,

+
>   CONSTRAINT fk_hosts_k FOREIGN KEY (host) REFERENCES public.hosts_t (id) ON 
+UPDATE CASCADE ON DELETE CASCADE

+
> ) WITH OIDS;

+
> 

+
> and

+
> 

+
> CREATE TABLE public.hosts_t

+
> (

+
>   id int4 NOT NULL,

+
>   ftime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,

+
>   utime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6) with time zone,

+
>   name text NOT NULL,

+
>   address inet NOT NULL,

+
>   CONSTRAINT pk_hosts_k PRIMARY KEY (id)

+
> ) WITH OIDS;

+
> 

+
> Table files_t has 249259 records and table hosts_t has only 59 records.

+
> 

+
> I tries to run simple query:

+
> 

+
> select * from files_t where parent = 3333

+
> 

+
> This query works 0.256 seconds! It is very big time for this small

+
> table!

+
> I have index for field "parent":

+
> 

+
> CREATE INDEX files_parent_idx

+
>   ON public.files_t

+
>   USING btree

+
>   (parent);

+
> 

+
> But if I tries to see query plan then I see following text:

+
> 

+
> Seq Scan on files_t (cost=0.00..6103.89 rows=54 width=102)

+
>  Filter: (parent = 3333)

+
> 

+
> PostgreSQL do not uses index files_parent_idx!

+
> 

+
> I have enabled all options of "QUERY TUNING" in postgresql.conf, I

+
> have increased memory sizes for PostgreSQL:

+
> 

+
> shared_buffers = 2000           # min 
+16, at least max_connections*2, 8KB each

+
> sort_mem = 32768                
+# min 64, size in KB

+
> vacuum_mem = 65536              
+# min 1024, size in KB

+
> fsync = false                   
+# turns forced synchronization on or off

+
> checkpoint_segments = 3 # in logfile segments, min 1, 16MB each

+
> enable_hashagg = true

+
> enable_hashjoin = true

+
> enable_indexscan = true

+
> enable_mergejoin = true

+
> enable_nestloop = true

+
> enable_seqscan = true

+
> enable_sort = true

+
> enable_tidscan = true

+
> geqo = true

+
> geqo_threshold = 22

+
> geqo_effort = 1

+
> geqo_generations = 0

+
> geqo_pool_size = 0              
+# default based on tables in statement,

+
>                                 
+# range 128-1024

+
> geqo_selection_bias = 2.0       # range 1.5-2.0

+
> stats_start_collector = true

+
> stats_command_string = true

+
> stats_block_level = true

+
> stats_row_level = true

+
> stats_reset_on_server_start = false

+
> 

+
> 

+
> Please help me!

+
> My database has a very small size (only 249259 records) but it works

+
> very slowly :(

+
> 

+
> Best regards

+
> Eugeny

+
> 

+
> 

+
> 

+
> 

+
> ---------------------------(end of broadcast)---------------------------

+
> TIP 3: if posting/reading through Usenet, please send an appropriate

+
>       subscribe-nomail command to majordomo@postgresql.org 
+so that your

+
>       message can get through to the mailing list cleanly

+


+

+

+
+
+
+--Alt-Boundary-1301.178492027--
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 18:51:22 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+	id 5A30F1FD0; Wed, 19 May 2004 17:51:00 -0400 (EDT)
+Message-ID: <40ABD6CC.3070206@samurai.com>
+Date: Wed, 19 May 2004 17:51:08 -0400
+From: Neil Conway 
+User-Agent: Mozilla Thunderbird 0.6 (Macintosh/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Eugeny Balakhonov 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL performance in simple queries
+References: <1117434122.20040520000757@mail.ru>
+In-Reply-To: <1117434122.20040520000757@mail.ru>
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Spam-Level: 
+X-Archive-Number: 200405/157
+X-Sequence-Number: 6988
+
+Eugeny Balakhonov wrote:
+> I tries to run simple query:
+> 
+> select * from files_t where parent = 3333
+
+Use this instead:
+
+select * from files_t where parent = '3333';
+
+("parent = 3333::int8" would work as well.)
+
+PostgreSQL (< 7.5) won't consider using an indexscan when the predicate 
+involves an integer literal and the column datatype is int2 or int8.
+
+-Neil
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 22:22:15 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 07172D1B17B
+	for ;
+	Wed, 19 May 2004 22:21:41 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
+	by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024)
+	with ESMTP id 01541-06
+	for ;
+	Wed, 19 May 2004 22:21:24 -0300 (ADT)
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+	by svr1.postgresql.org (Postfix) with ESMTP id 9D5E8D1B188
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+	Wed, 19 May 2004 22:21:19 -0300 (ADT)
+Received: (from pgman@localhost)
+	by candle.pha.pa.us (8.11.6/8.11.6) id i4K1KKm06350;
+	Wed, 19 May 2004 21:20:20 -0400 (EDT)
+From: Bruce Momjian 
+Message-Id: <200405200120.i4K1KKm06350@candle.pha.pa.us>
+Subject: Re: Wierd context-switching issue on Xeon
+In-Reply-To: <1083512362.25096.131.camel@localhost.localdomain>
+To: pg@fastcrypt.com
+Date: Wed, 19 May 2004 21:20:20 -0400 (EDT)
+Cc: Robert Creager ,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Tom Lane ,
+	Joe Conway , "scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
+MIME-Version: 1.0
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+X-Archive-Number: 200405/158
+X-Sequence-Number: 6989
+
+
+Did we ever come to a conclusion about excessive SMP context switching
+under load?
+
+---------------------------------------------------------------------------
+
+Dave Cramer wrote:
+> Robert,
+> 
+> The real question is does it help under real life circumstances ? 
+> 
+> Did you do the tests with Tom's sql code that is designed to create high
+> context switchs ?
+> 
+> Dave
+> On Sun, 2004-05-02 at 11:20, Robert Creager wrote:
+> > Found some co-workers at work yesterday to load up my library...
+> > 
+> > The sample period is 5 minutes long (vs 2 minutes previously):
+> > 
+> > Context switches -          avg    max
+> > 
+> > Default 7.4.1 code :       48784 107354
+> > Default patch - 10 :       20400  28160
+> > patch at 100       :       38574  85372
+> > patch at 1000      :       41188 106569
+> > 
+> > The reading at 1000 was not produced under the same circumstances as the prior
+> > readings as I had to replace my device under test with a simulated one.  The
+> > real one died.
+> > 
+> > The previous run with smaller database and 120 second averages:
+> > 
+> > Context switches -          avg    max
+> > 
+> > Default 7.4.1 code :       10665  69470
+> > Default patch - 10 :       17297  21929
+> > patch at 100       :       26825  87073
+> > patch at 1000      :       37580 110849
+> -- 
+> Dave Cramer
+> 519 939 0336
+> ICQ # 14675561
+> 
+> 
+> ---------------------------(end of broadcast)---------------------------
+> TIP 7: don't forget to increase your free space map settings
+> 
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 23:00:51 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Wed, 19 May 2004 19:59:34 -0600 (MDT)
+Date: Wed, 19 May 2004 19:59:26 -0600
+From: Robert Creager 
+To: Bruce Momjian 
+Cc: pg@fastcrypt.com, Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk?= =?ISO-8859-1?Q?=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Tom Lane ,
+	Joe Conway , "scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon
+Message-Id: <20040519195926.3c5fa3bc@thunder.mshome.net>
+In-Reply-To: <200405200120.i4K1KKm06350@candle.pha.pa.us>
+References: <1083512362.25096.131.camel@localhost.localdomain>
+	<200405200120.i4K1KKm06350@candle.pha.pa.us>
+Organization: Starlight Vision, LLC.
+X-Mailer: Sylpheed version 0.9.10claws (GTK+ 1.2.10; i586-mandrake-linux-gnu)
+Mime-Version: 1.0
+Content-Type: multipart/signed; protocol="application/pgp-signature";
+	micalg="pgp-sha1";
+	boundary="Signature=_Wed__19_May_2004_19_59_26_-0600_qr.ctZpT0duCxZPR"
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+--Signature=_Wed__19_May_2004_19_59_26_-0600_qr.ctZpT0duCxZPR
+Content-Type: text/plain; charset=US-ASCII
+Content-Disposition: inline
+Content-Transfer-Encoding: 7bit
+
+When grilled further on (Wed, 19 May 2004 21:20:20 -0400 (EDT)),
+Bruce Momjian  confessed:
+
+> 
+> Did we ever come to a conclusion about excessive SMP context switching
+> under load?
+> 
+
+I just figured out what was causing the problem on my system Monday.  I'm using
+the pg_autovacuum daemon, and it was not vacuuming my db.  I've no idea why and
+didn't get a chance to investigate.
+
+This lack of vacuuming was causing a huge number of context switches and query
+delays. the queries that normally take .1 seconds were taking 11 seconds, and
+the context switches were averaging 160k/s, peaking at 190k/s
+
+Unfortunately, I was under pressure to fix the db at the time so I didn't get a
+chance to play with the patch.
+
+I restarted the vacuum daemon, and will keep an eye on it to see if it behaves.
+
+If the problem re-occurs, is it worth while to attempt the different patch
+delay settings?
+
+Cheers,
+Rob
+
+-- 
+ 19:45:40 up 21 days,  2:30,  4 users,  load average: 2.03, 2.09, 2.06
+Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004
+
+--Signature=_Wed__19_May_2004_19_59_26_-0600_qr.ctZpT0duCxZPR
+Content-Type: application/pgp-signature
+
+-----BEGIN PGP SIGNATURE-----
+Version: GnuPG v1.2.4 (GNU/Linux)
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+=WXZG
+-----END PGP SIGNATURE-----
+
+--Signature=_Wed__19_May_2004_19_59_26_-0600_qr.ctZpT0duCxZPR--
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 23:42:51 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id D5746D1B1CF
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+	by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i4K2fQ47024374;
+	Wed, 19 May 2004 22:41:26 -0400 (EDT)
+To: Bruce Momjian 
+Cc: pg@fastcrypt.com, Robert Creager ,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon 
+In-reply-to: <200405200120.i4K1KKm06350@candle.pha.pa.us> 
+References: <200405200120.i4K1KKm06350@candle.pha.pa.us>
+Comments: In-reply-to Bruce Momjian 
+	message dated "Wed, 19 May 2004 21:20:20 -0400"
+Date: Wed, 19 May 2004 22:41:26 -0400
+Message-ID: <24373.1085020886@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/160
+X-Sequence-Number: 6991
+
+Bruce Momjian  writes:
+> Did we ever come to a conclusion about excessive SMP context switching
+> under load?
+
+Yeah: it's bad.
+
+Oh, you wanted a fix?  That seems harder :-(.  AFAICS we need a redesign
+that causes less load on the BufMgrLock.  However, the traditional
+solution to too-much-contention-for-a-lock is to break up the locked
+data structure into finer-grained units, which means *more* lock
+operations in total.  Normally you expect that the finer-grained lock
+units will mean less contention.  But given that the issue here seems to
+be trading physical ownership of the lock's cache line back and forth,
+I'm afraid that the traditional approach would actually make things
+worse.  The SMP issue seems to be not with whether there is
+instantaneous contention for the locked datastructure, but with the cost
+of making it possible for processor B to acquire a lock recently held by
+processor A.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Wed May 19 23:44:02 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id D06B3D1B1CF
+	for ;
+	Wed, 19 May 2004 23:43:22 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
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+	Wed, 19 May 2004 22:42:26 -0400 (EDT)
+To: Robert Creager 
+Cc: Bruce Momjian , pg@fastcrypt.com,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk?= =?ISO-8859-1?Q?=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon 
+In-reply-to: <20040519195926.3c5fa3bc@thunder.mshome.net> 
+References: <1083512362.25096.131.camel@localhost.localdomain>
+	<200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<20040519195926.3c5fa3bc@thunder.mshome.net>
+Comments: In-reply-to Robert Creager 
+	message dated "Wed, 19 May 2004 19:59:26 -0600"
+Date: Wed, 19 May 2004 22:42:26 -0400
+Message-ID: <24405.1085020946@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/161
+X-Sequence-Number: 6992
+
+Robert Creager  writes:
+> I just figured out what was causing the problem on my system Monday.
+> I'm using the pg_autovacuum daemon, and it was not vacuuming my db.
+
+Do you have the post-7.4.2 datatype fixes for pg_autovacuum?
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 00:07:05 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+	Wed, 19 May 2004 20:59:23 -0600 (MDT)
+Date: Wed, 19 May 2004 20:59:21 -0600
+From: Robert Creager 
+To: Tom Lane 
+Cc: Bruce Momjian , pg@fastcrypt.com,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon
+Message-Id: <20040519205921.46510067@thunder.mshome.net>
+In-Reply-To: <24405.1085020946@sss.pgh.pa.us>
+References: <1083512362.25096.131.camel@localhost.localdomain>
+	<200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<20040519195926.3c5fa3bc@thunder.mshome.net>
+	<24405.1085020946@sss.pgh.pa.us>
+Organization: Starlight Vision, LLC.
+X-Mailer: Sylpheed version 0.9.10claws (GTK+ 1.2.10; i586-mandrake-linux-gnu)
+Mime-Version: 1.0
+Content-Type: multipart/signed; protocol="application/pgp-signature";
+	micalg="pgp-sha1";
+	boundary="Signature=_Wed__19_May_2004_20_59_21_-0600_w/th.GtNChfsNfUS"
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+
+--Signature=_Wed__19_May_2004_20_59_21_-0600_w/th.GtNChfsNfUS
+Content-Type: text/plain; charset=US-ASCII
+Content-Disposition: inline
+Content-Transfer-Encoding: 7bit
+
+When grilled further on (Wed, 19 May 2004 22:42:26 -0400),
+Tom Lane  confessed:
+
+> Robert Creager  writes:
+> > I just figured out what was causing the problem on my system Monday.
+> > I'm using the pg_autovacuum daemon, and it was not vacuuming my db.
+> 
+> Do you have the post-7.4.2 datatype fixes for pg_autovacuum?
+
+No.  I'm still running 7.4.1 w/associated contrib.  I guess an upgrade is in
+order then.  I'm currently downloading 7.4.2 to see what the change is that I
+need.  Is it just the 7.4.2 pg_autovacuum that is needed here?
+
+I've caught a whiff that 7.4.3 is nearing release?  Any idea when?
+
+Thanks,
+Rob
+
+-- 
+ 20:45:52 up 21 days,  3:30,  4 users,  load average: 2.02, 2.05, 2.05
+Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004
+
+--Signature=_Wed__19_May_2004_20_59_21_-0600_w/th.GtNChfsNfUS
+Content-Type: application/pgp-signature
+
+-----BEGIN PGP SIGNATURE-----
+Version: GnuPG v1.2.4 (GNU/Linux)
+
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+uRkAnRrIYj/zW20IW3BBWYM6V61uJCl0
+=J81W
+-----END PGP SIGNATURE-----
+
+--Signature=_Wed__19_May_2004_20_59_21_-0600_w/th.GtNChfsNfUS--
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 00:05:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 2C36CD1B1BD
+	for ;
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+Received: (from pgman@localhost)
+	by candle.pha.pa.us (8.11.6/8.11.6) id i4K32G721749;
+	Wed, 19 May 2004 23:02:16 -0400 (EDT)
+From: Bruce Momjian 
+Message-Id: <200405200302.i4K32G721749@candle.pha.pa.us>
+Subject: Re: Wierd context-switching issue on Xeon
+In-Reply-To: <24373.1085020886@sss.pgh.pa.us>
+To: Tom Lane 
+Date: Wed, 19 May 2004 23:02:16 -0400 (EDT)
+Cc: pg@fastcrypt.com, Robert Creager ,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain; charset=US-ASCII
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/162
+X-Sequence-Number: 6993
+
+Tom Lane wrote:
+> Bruce Momjian  writes:
+> > Did we ever come to a conclusion about excessive SMP context switching
+> > under load?
+> 
+> Yeah: it's bad.
+> 
+> Oh, you wanted a fix?  That seems harder :-(.  AFAICS we need a redesign
+> that causes less load on the BufMgrLock.  However, the traditional
+> solution to too-much-contention-for-a-lock is to break up the locked
+> data structure into finer-grained units, which means *more* lock
+> operations in total.  Normally you expect that the finer-grained lock
+> units will mean less contention.  But given that the issue here seems to
+> be trading physical ownership of the lock's cache line back and forth,
+> I'm afraid that the traditional approach would actually make things
+> worse.  The SMP issue seems to be not with whether there is
+> instantaneous contention for the locked datastructure, but with the cost
+> of making it possible for processor B to acquire a lock recently held by
+> processor A.
+
+I see.  I don't even see a TODO in there.  :-(
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 01:01:01 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id BC240D1B4A8
+	for ;
+	Thu, 20 May 2004 01:00:22 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
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+	by sss.pgh.pa.us (8.12.11/8.12.11) with ESMTP id i4K3wujN025438;
+	Wed, 19 May 2004 23:58:56 -0400 (EDT)
+To: Bruce Momjian 
+Cc: pg@fastcrypt.com, Robert Creager ,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon 
+In-reply-to: <200405200302.i4K32G721749@candle.pha.pa.us> 
+References: <200405200302.i4K32G721749@candle.pha.pa.us>
+Comments: In-reply-to Bruce Momjian 
+	message dated "Wed, 19 May 2004 23:02:16 -0400"
+Date: Wed, 19 May 2004 23:58:56 -0400
+Message-ID: <25437.1085025536@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/164
+X-Sequence-Number: 6995
+
+Bruce Momjian  writes:
+> Tom Lane wrote:
+>> ...  The SMP issue seems to be not with whether there is
+>> instantaneous contention for the locked datastructure, but with the cost
+>> of making it possible for processor B to acquire a lock recently held by
+>> processor A.
+
+> I see.  I don't even see a TODO in there.  :-(
+
+Nothing more specific than "investigate SMP context switching issues",
+anyway.  We are definitely in a research mode here, rather than an
+engineering mode.
+
+ObQuote: "Research is what I am doing when I don't know what I am
+doing." - attributed to Werner von Braun, but has anyone got a
+definitive reference?
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 01:05:39 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 00:02:41 -0400 (EDT)
+To: Robert Creager 
+Cc: Bruce Momjian , pg@fastcrypt.com,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon 
+In-reply-to: <20040519205921.46510067@thunder.mshome.net> 
+References: <1083512362.25096.131.camel@localhost.localdomain>
+	<200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<20040519195926.3c5fa3bc@thunder.mshome.net>
+	<24405.1085020946@sss.pgh.pa.us>
+	<20040519205921.46510067@thunder.mshome.net>
+Comments: In-reply-to Robert Creager 
+	message dated "Wed, 19 May 2004 20:59:21 -0600"
+Date: Thu, 20 May 2004 00:02:41 -0400
+Message-ID: <25480.1085025761@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/165
+X-Sequence-Number: 6996
+
+Robert Creager  writes:
+> Tom Lane  confessed:
+>> Do you have the post-7.4.2 datatype fixes for pg_autovacuum?
+
+> No.  I'm still running 7.4.1 w/associated contrib.  I guess an upgrade is in
+> order then.  I'm currently downloading 7.4.2 to see what the change is that I
+> need.  Is it just the 7.4.2 pg_autovacuum that is needed here?
+
+Nope, the fixes I was thinking about just missed the 7.4.2 release.
+I think you can only get them from CVS.  (Maybe we should offer a
+nightly build of the latest stable release branch, not only development
+tip...)
+
+> I've caught a whiff that 7.4.3 is nearing release?  Any idea when?
+
+Not scheduled yet, but there was talk of pushing one out before 7.5 goes
+into feature freeze.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 01:12:54 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+From: Bruce Momjian 
+Message-Id: <200405200411.i4K4B5F03803@candle.pha.pa.us>
+Subject: Re: Wierd context-switching issue on Xeon
+In-Reply-To: <25437.1085025536@sss.pgh.pa.us>
+To: Tom Lane 
+Date: Thu, 20 May 2004 00:11:05 -0400 (EDT)
+Cc: pg@fastcrypt.com, Robert Creager ,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain; charset=US-ASCII
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Spam-Level: 
+X-Archive-Number: 200405/166
+X-Sequence-Number: 6997
+
+
+OK, added to TODO:
+
+	* Investigate SMP context switching issues
+
+
+---------------------------------------------------------------------------
+
+Tom Lane wrote:
+> Bruce Momjian  writes:
+> > Tom Lane wrote:
+> >> ...  The SMP issue seems to be not with whether there is
+> >> instantaneous contention for the locked datastructure, but with the cost
+> >> of making it possible for processor B to acquire a lock recently held by
+> >> processor A.
+> 
+> > I see.  I don't even see a TODO in there.  :-(
+> 
+> Nothing more specific than "investigate SMP context switching issues",
+> anyway.  We are definitely in a research mode here, rather than an
+> engineering mode.
+> 
+> ObQuote: "Research is what I am doing when I don't know what I am
+> doing." - attributed to Werner von Braun, but has anyone got a
+> definitive reference?
+> 
+> 			regards, tom lane
+> 
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 01:13:36 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 00:11:57 -0400 (EDT)
+From: Bruce Momjian 
+Message-Id: <200405200411.i4K4BvV03958@candle.pha.pa.us>
+Subject: Re: Wierd context-switching issue on Xeon
+In-Reply-To: <25480.1085025761@sss.pgh.pa.us>
+To: Tom Lane 
+Date: Thu, 20 May 2004 00:11:57 -0400 (EDT)
+Cc: Robert Creager ,
+	pg@fastcrypt.com, Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain; charset=US-ASCII
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Spam-Level: 
+X-Archive-Number: 200405/167
+X-Sequence-Number: 6998
+
+Tom Lane wrote:
+> Robert Creager  writes:
+> > Tom Lane  confessed:
+> >> Do you have the post-7.4.2 datatype fixes for pg_autovacuum?
+> 
+> > No.  I'm still running 7.4.1 w/associated contrib.  I guess an upgrade is in
+> > order then.  I'm currently downloading 7.4.2 to see what the change is that I
+> > need.  Is it just the 7.4.2 pg_autovacuum that is needed here?
+> 
+> Nope, the fixes I was thinking about just missed the 7.4.2 release.
+> I think you can only get them from CVS.  (Maybe we should offer a
+> nightly build of the latest stable release branch, not only development
+> tip...)
+> 
+> > I've caught a whiff that 7.4.3 is nearing release?  Any idea when?
+> 
+> Not scheduled yet, but there was talk of pushing one out before 7.5 goes
+> into feature freeze.
+
+We need the temp table autovacuum fix before we do 7.4.3.
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 02:19:52 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+From: Christopher Browne 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: Wierd context-switching issue on Xeon
+Date: Thu, 20 May 2004 00:48:48 -0400
+Organization: cbbrowne Computing Inc
+Lines: 12
+Message-ID: 
+References: <200405200302.i4K32G721749@candle.pha.pa.us>
+	<25437.1085025536@sss.pgh.pa.us>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+X-Complaints-To: usenet@news.hub.org
+X-message-flag: Outlook is rather hackable, isn't it?
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+ Obscurity,
+	linux)
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+To: pgsql-performance@postgresql.org
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+X-Archive-Number: 200405/170
+X-Sequence-Number: 7001
+
+In an attempt to throw the authorities off his trail, tgl@sss.pgh.pa.us (Tom Lane) transmitted:
+> ObQuote: "Research is what I am doing when I don't know what I am
+> doing." - attributed to Werner von Braun, but has anyone got a
+> definitive reference?
+
+
+
+That points to a bunch of seemingly authoritative sources...
+-- 
+(reverse (concatenate 'string "moc.enworbbc" "@" "enworbbc"))
+http://www.ntlug.org/~cbbrowne/lsf.html
+"Terrrrrific." -- Ford Prefect
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 02:19:50 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
+	Thu, 20 May 2004 02:19:49 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
+	by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024)
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+	for pgsql-performance@postgresql.org; Thu, 20 May 2004 04:49:43 GMT
+From: Joseph Shraibman 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: PostgreSQL performance in simple queries
+Date: Thu, 20 May 2004 00:49:43 -0400
+Organization: Hub.Org Networking Services
+Lines: 7
+Message-ID: 
+References: <1117434122.20040520000757@mail.ru> <40ABD6CC.3070206@samurai.com>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Accept-Language: en-us, en
+In-Reply-To: <40ABD6CC.3070206@samurai.com>
+To: pgsql-performance@postgresql.org
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+X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
+X-Spam-Level: 
+X-Archive-Number: 200405/169
+X-Sequence-Number: 7000
+
+Neil Conway wrote:
+
+> PostgreSQL (< 7.5) won't consider using an indexscan when the predicate 
+> involves an integer literal and the column datatype is int2 or int8.
+
+Is this fixed for 7.5?  It isn't checked off on the TODO list at
+http://developer.postgresql.org/todo.php
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 02:11:16 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id 1BQfow-000FWV-SE; Thu, 20 May 2004 01:10:18 -0400
+Subject: Re: Wierd context-switching issue on Xeon
+From: "Matthew T. O'Connor" 
+To: Robert Creager 
+Cc: Bruce Momjian , pg@fastcrypt.com,
+	Josh Berkus ,
+	=?ISO-8859-1?Q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Tom Lane ,
+	Joe Conway , "scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+In-Reply-To: <20040519195926.3c5fa3bc@thunder.mshome.net>
+References: <1083512362.25096.131.camel@localhost.localdomain>
+	<200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<20040519195926.3c5fa3bc@thunder.mshome.net>
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+	http://www.mailhop.org/outbound/abuse.html for abuse reporting
+	information)
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+X-Sequence-Number: 6999
+
+On Wed, 2004-05-19 at 21:59, Robert Creager wrote:
+> When grilled further on (Wed, 19 May 2004 21:20:20 -0400 (EDT)),
+> Bruce Momjian  confessed:
+> 
+> > 
+> > Did we ever come to a conclusion about excessive SMP context switching
+> > under load?
+> > 
+> 
+> I just figured out what was causing the problem on my system Monday.  I'm using
+> the pg_autovacuum daemon, and it was not vacuuming my db.  I've no idea why and
+> didn't get a chance to investigate.
+
+Strange.  There is a known bug in the 7.4.2 version of pg_autovacuum
+related to data type mismatches which is fixed in CVS.  But that bug
+doesn't cause pg_autovacuum to stop vacuuming but rather to vacuum to
+often.  So perhaps this is a different issue?  Please let me know what
+you find.
+
+Thanks,
+
+Matthew O'Connor
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 06:28:19 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Received: from svr1.postgresql.org ([200.46.204.71])
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+Date: Thu, 20 May 2004 21:28:28 +1200
+From: Mark Kirkwood 
+Subject: Re: DB Design
+In-reply-to: <200405190724.i4J7NuPW030497@mail.census.gov.ph>
+To: "Michael Ryan S. Puncia" 
+Cc: pgsql-performance@postgresql.org
+Message-id: <40AC7A3C.2050001@paradise.net.nz>
+MIME-version: 1.0
+Content-type: text/plain; format=flowed; charset=ISO-8859-1
+Content-transfer-encoding: 7bit
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+X-Sequence-Number: 7002
+
+The complete answer is probably "it depends", but this does not help 
+much...:-)
+
+I would try out the simple approach first (i.e one 50 million row 
+table), but read up about :
+
+i) partial indexes and maybe
+ii) clustering
+iii) think about presorting the data before loading to place "likely to 
+be accessed" rows "close" together in the table (if possible).
+iv) get to know the analyze, explain, explain analyze commands....
+
+Best wishes
+
+Mark
+
+Michael Ryan S. Puncia wrote:
+
+> Hi Guys,
+>
+>   
+>
+>       My question is .. which is better design
+>
+>  
+>
+>    1. Single Table with 50 million records or
+>    2. Multiple Table using inheritance to the parents table
+>
+>  
+>
+>  
+>
+> I will use this only for query purpose ..
+>
+>  
+>
+> Thanks ..
+>
+>  
+>
+>  
+>
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 10:46:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 346BFD1B182
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+Date: Thu, 20 May 2004 07:46:08 -0600
+From: Marty Scholes 
+User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:0.9.9) Gecko/20020517
+X-Accept-Language: en-us, en
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+To: pgsql-performance@postgresql.org
+Subject: Re: Hardware Platform
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+
+Duane wrote:
+
+ > P.S. I've only just begun using PostgreSQL after having
+ > used (and still using) DB2 on a mainframe for the past 14
+ > years.  My experience with Unix/Linux is limited to some
+ > community college classes I've taken but we do have
+ > a couple of experienced Linux sysadmins on our team.
+ > I tell you this because my "ignorance" will probably
+ > show more than once in my inquiries.
+
+Duane,
+
+If you've been actively using and developing in DB2, presumably under 
+MVS or whatever big blue is calling it these days, for 14 years, then 
+you will bring a wealth of big system expertise to Pg.
+
+Please stay involved and make suggestions where you thing Pg could be 
+improved.
+
+Marty
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 12:38:24 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 11:33:59 -0400 (EDT)
+To: Joseph Shraibman 
+Cc: pgsql-performance@postgresql.org,
+	Bruce Momjian 
+Subject: Re: PostgreSQL performance in simple queries 
+In-reply-to:  
+References: <1117434122.20040520000757@mail.ru> <40ABD6CC.3070206@samurai.com>
+	
+Comments: In-reply-to Joseph Shraibman 
+	message dated "Thu, 20 May 2004 00:49:43 -0400"
+Date: Thu, 20 May 2004 11:33:59 -0400
+Message-ID: <1454.1085067239@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Joseph Shraibman  writes:
+> Neil Conway wrote:
+>> PostgreSQL (< 7.5) won't consider using an indexscan when the predicate 
+>> involves an integer literal and the column datatype is int2 or int8.
+
+> Is this fixed for 7.5?  It isn't checked off on the TODO list at
+> http://developer.postgresql.org/todo.php
+
+It is.  I don't know why Bruce hasn't checked it off.
+
+
+Some other stuff that needs work in TODO:
+
+: Bracketed items "[]" have more detailed.
+
+More detailed what?  Grammar please.
+
+: * Remove unreferenced table files and temp tables during database vacuum
+:   or postmaster startup (Bruce)
+
+I'm not sure this is still needed given that we now log file deletion in
+WAL.
+
+: * Allow pg_dump to dump sequences using NO_MAXVALUE and NO_MINVALUE
+
+Seems to be done.
+
+: * Prevent whole-row references from leaking memory, e.g. SELECT COUNT(tab.*)
+
+Done.
+
+: * Make LENGTH() of CHAR() not count trailing spaces
+
+Done.
+
+: * Allow SELECT * FROM tab WHERE int2col = 4 to use int2col index, int8,
+:   float4, numeric/decimal too
+
+Done, per above.
+
+: * Allow more ISOLATION LEVELS to be accepted, but issue a warning for them
+
+Presently we accept all four with no warning ...
+
+: * Add GUC setting to make created tables default to WITHOUT OIDS
+
+Seems to be done, other than the argument about how pg_dump should work.
+
+: * Allow fastpast to pass values in portable format
+
+This was done in 7.4.
+
+: * Move psql backslash database information into the backend, use nmumonic
+:   commands? [psql]
+
+Spelling problem...
+
+: * JDBC
+
+With JDBC out of the core, I'm not sure why we still have a JDBC section
+in the core TODO.
+
+: * Have pg_dump -c clear the database using dependency information
+
+I think this works now.  Not really tested, but in principle it should
+work.
+
+: * Cache last known per-tuple offsets to speed long tuple access
+
+This sounds exactly like attcacheoff, which has been there since
+Berkeley.  Either remove this or fix the description to give some
+idea what's really meant.
+
+: * Automatically place fixed-width, NOT NULL columns first in a table
+
+This is not ever going to happen, given that we've rejected the idea of
+having separate logical and physical column positions.
+
+: * Change representation of whole-tuple parameters to functions
+
+Done.  (However, you might want to add something about supporting
+composite types as table columns, which isn't done.)
+
+: * Allow the regression tests to start postmaster with -i so the tests
+:   can be run on systems that don't support unix-domain sockets
+
+Done long ago.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 12:58:32 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 11:56:55 -0400 (EDT)
+From: Bruce Momjian 
+Message-Id: <200405201556.i4KFutB17015@candle.pha.pa.us>
+Subject: Re: PostgreSQL performance in simple queries
+In-Reply-To: <1454.1085067239@sss.pgh.pa.us>
+To: Tom Lane 
+Date: Thu, 20 May 2004 11:56:55 -0400 (EDT)
+Cc: Joseph Shraibman , pgsql-performance@postgresql.org,
+	PostgreSQL-development 
+X-Mailer: ELM [version 2.4ME+ PL108 (25)]
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+X-Sequence-Number: 7005
+
+Tom Lane wrote:
+> Joseph Shraibman  writes:
+> > Neil Conway wrote:
+> >> PostgreSQL (< 7.5) won't consider using an indexscan when the predicate 
+> >> involves an integer literal and the column datatype is int2 or int8.
+> 
+> > Is this fixed for 7.5?  It isn't checked off on the TODO list at
+> > http://developer.postgresql.org/todo.php
+> 
+> It is.  I don't know why Bruce hasn't checked it off.
+> 
+
+
+OK, marked as done:
+
+* -Allow SELECT * FROM tab WHERE int2col = 4 to use int2col index, int8,
+  float4, numeric/decimal too
+> 
+> Some other stuff that needs work in TODO:
+> 
+> : Bracketed items "[]" have more detailed.
+> 
+> More detailed what?  Grammar please.
+
+Fixed.  "more detail".
+
+> : * Remove unreferenced table files and temp tables during database vacuum
+> :   or postmaster startup (Bruce)
+> 
+> I'm not sure this is still needed given that we now log file deletion in
+> WAL.
+
+OK, removed.
+
+> 
+> : * Allow pg_dump to dump sequences using NO_MAXVALUE and NO_MINVALUE
+> 
+> Seems to be done.
+
+
+OK.
+
+
+> 
+> : * Prevent whole-row references from leaking memory, e.g. SELECT COUNT(tab.*)
+> 
+> Done.
+
+OK.
+
+> 
+> : * Make LENGTH() of CHAR() not count trailing spaces
+> 
+> Done.
+
+OK.
+
+> 
+> : * Allow SELECT * FROM tab WHERE int2col = 4 to use int2col index, int8,
+> :   float4, numeric/decimal too
+> 
+> Done, per above.
+
+Got it.
+
+> 
+> : * Allow more ISOLATION LEVELS to be accepted, but issue a warning for them
+> 
+> Presently we accept all four with no warning ...
+
+OK.  Warning part removed.
+
+> 
+> : * Add GUC setting to make created tables default to WITHOUT OIDS
+> 
+> Seems to be done, other than the argument about how pg_dump should work.
+
+I did the pg_dump part using SET only where needed.  That is done.
+
+> 
+> : * Allow fastpast to pass values in portable format
+> 
+> This was done in 7.4.
+
+
+Removed.
+
+> 
+> : * Move psql backslash database information into the backend, use nmumonic
+> :   commands? [psql]
+> 
+> Spelling problem...
+
+Fixed.
+
+> 
+> : * JDBC
+> 
+> With JDBC out of the core, I'm not sure why we still have a JDBC section
+> in the core TODO.
+
+Removed.  If they want it they can get it from our CVS history.
+
+> : * Have pg_dump -c clear the database using dependency information
+> 
+> I think this works now.  Not really tested, but in principle it should
+> work.
+
+OK.
+> 
+> : * Cache last known per-tuple offsets to speed long tuple access
+> 
+> This sounds exactly like attcacheoff, which has been there since
+> Berkeley.  Either remove this or fix the description to give some
+> idea what's really meant.
+
+Added "adjusting for NULLs and TOAST values.  The issue is that when
+NULLs or TOAST is present, those aren't useful.  I was thinking we could
+remember the pattern of the previous row and use those offsets if the
+TOAST/NULL pattern was the same, or something like that.  Is that a
+valid idea?
+
+> : * Automatically place fixed-width, NOT NULL columns first in a table
+> 
+> This is not ever going to happen, given that we've rejected the idea of
+> having separate logical and physical column positions.
+
+Removed.
+
+> 
+> : * Change representation of whole-tuple parameters to functions
+> 
+> Done.  (However, you might want to add something about supporting
+> composite types as table columns, which isn't done.)
+
+OK, marked a done, and added new line:
+
+	* Support composite types as table columns
+
+> : * Allow the regression tests to start postmaster with -i so the tests
+> :   can be run on systems that don't support unix-domain sockets
+> 
+> Done long ago.
+
+Removed.
+
+
+Thanks for the updates!
+
+
+
+-- 
+  Bruce Momjian                        |  http://candle.pha.pa.us
+  pgman@candle.pha.pa.us               |  (610) 359-1001
+  +  If your life is a hard drive,     |  13 Roberts Road
+  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 13:01:22 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+In-Reply-To: <6.0.1.1.2.20040518133210.01eb9ec0@mail.traderonline.com>
+Subject: Re: Interpreting vmstat
+To: Doug Y 
+Cc: pgsql-performance@postgresql.org
+X-Mailer: Lotus Notes Release 6.5.1 January 21, 2004
+Message-ID: 
+ 
+From: Thom Dyson 
+Date: Thu, 20 May 2004 09:00:22 -0700
+X-MIMETrack: Serialize by Router on Bert/Sybex(Release 6.5|September 18,
+	2003) at 05/20/2004 09:00:25 AM
+MIME-Version: 1.0
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+X-Archive-Number: 200405/175
+X-Sequence-Number: 7006
+
+
+
+
+
+Well,
+
+Since I haven't seen any other responds, I'll offer a bit of advice and let
+others correct me. :)
+
+Your shared buffers may be too big (?).  It is much larger than the guide
+on varlena.com recommends.  All I can suggest is trying some experiments
+with halving/doubling the numbers to see which way performance goes.  Also,
+if you are counting on cache to improve performance, then the db has to be
+loaded into cache the first time. So, are subsequent re-queries faster?
+
+Thom Dyson
+Director of Information Services
+Sybex, Inc.
+
+
+
+pgsql-performance-owner@postgresql.org wrote on 05/18/2004 11:12:14 AM:
+
+> Hello,
+> (note best viewed in fixed-width font)
+>
+> I'm still trying to find where my performance bottle neck is...
+> I have 4G ram, PG 7.3.4
+> shared_buffers = 75000
+> effective_cache_size = 75000
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 13:57:22 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 12:52:13 -0400
+Message-ID: <40ACE23D.2090501@selectacast.net>
+Date: Thu, 20 May 2004 12:52:13 -0400
+From: Joseph Shraibman 
+User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040514
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: tgl@sss.pgh.pa.us, Bruce Momjian 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL performance in simple queries
+References: <1117434122.20040520000757@mail.ru> <40ABD6CC.3070206@samurai.com>
+	 <1454.1085067239@sss.pgh.pa.us>
+In-Reply-To: <1454.1085067239@sss.pgh.pa.us>
+Content-Type: text/plain; charset=us-ascii; format=flowed
+Content-Transfer-Encoding: 7bit
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+X-Spam-Level: 
+X-Archive-Number: 200405/176
+X-Sequence-Number: 7007
+
+Tom Lane wrote:
+
+> 
+> : * JDBC
+> 
+> With JDBC out of the core, I'm not sure why we still have a JDBC section
+> in the core TODO.
+
+Speaking of which why is the jdbc site so hard to find?  For that matter 
+the new foundry can only be found through the news article on the front 
+page.
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 18:52:18 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
+	Thu, 20 May 2004 18:52:16 -0300 (ADT)
+Received: from svr1.postgresql.org ([200.46.204.71])
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+	[209.128.84.228])
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+	by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.1.8)
+	with ESMTP id 5145531; Thu, 20 May 2004 14:53:25 -0700
+From: Josh Berkus 
+Reply-To: josh@agliodbs.com
+Organization: Aglio Database Solutions
+To: Tom Lane ,
+	Bruce Momjian 
+Subject: Re: Wierd context-switching issue on Xeon
+Date: Thu, 20 May 2004 14:52:07 -0700
+User-Agent: KMail/1.5.4
+Cc: pg@fastcrypt.com, Robert Creager ,
+	=?iso-8859-1?q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+References: <200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<24373.1085020886@sss.pgh.pa.us>
+In-Reply-To: <24373.1085020886@sss.pgh.pa.us>
+MIME-Version: 1.0
+Content-Type: text/plain;
+  charset="iso-8859-1"
+Content-Transfer-Encoding: 7bit
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+Message-Id: <200405201452.07833.josh@agliodbs.com>
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Archive-Number: 200405/177
+X-Sequence-Number: 7008
+
+Guys,
+ 
+> Oh, you wanted a fix?  That seems harder :-(.  AFAICS we need a redesign
+> that causes less load on the BufMgrLock.
+
+FWIW, we've been pursuing two routes of quick patch fixes.
+
+1) Dave Cramer and I have been testing setting varying rates of spin_delay in 
+an effort to find a "sweet spot" that the individual system seems to like.   
+This has been somewhat delayed by my illness.
+
+2) The OSDL folks have been trying various patches to use Linux 2.6 Futexes in 
+place of semops (if I have that right) which, if successful, would produce a 
+linux-specific fix.   However, they haven't yet come up wiith a version of 
+the patch which is stable.
+
+I'm really curious, BTW, about how all of Jan's changes to buffer usage in 7.5 
+affect this issue.   Has anyone tested it on a recent snapshot?
+
+-- 
+-Josh Berkus
+ Aglio Database Solutions
+ San Francisco
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 20 19:16:01 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Thu, 20 May 2004 18:14:52 -0400 (EDT)
+To: josh@agliodbs.com
+Cc: Bruce Momjian , pg@fastcrypt.com,
+	Robert Creager ,
+	=?iso-8859-1?q?Dirk=5FLutzeb=E4ck?= ,
+	ohp@pyrenet.fr, Joe Conway ,
+	"scott.marlowe" ,
+	pgsql-performance@postgresql.org, Neil Conway 
+Subject: Re: Wierd context-switching issue on Xeon 
+In-reply-to: <200405201452.07833.josh@agliodbs.com> 
+References: <200405200120.i4K1KKm06350@candle.pha.pa.us>
+	<24373.1085020886@sss.pgh.pa.us>
+	<200405201452.07833.josh@agliodbs.com>
+Comments: In-reply-to Josh Berkus 
+	message dated "Thu, 20 May 2004 14:52:07 -0700"
+Date: Thu, 20 May 2004 18:14:52 -0400
+Message-ID: <24678.1085091292@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Josh Berkus  writes:
+> I'm really curious, BTW, about how all of Jan's changes to buffer
+> usage in 7.5 affect this issue.  Has anyone tested it on a recent
+> snapshot?
+
+Won't help.
+
+(1) Theoretical argument: the problem case is select-only and touches
+few enough buffers that it need never visit the kernel.  The buffer
+management algorithm is thus irrelevant since there are never any
+decisions for it to make.  If anything CVS tip will have a worse problem
+because its more complicated management algorithm needs to spend longer
+holding the BufMgrLock.
+
+(2) Experimental argument: I believe that I did check the self-contained
+test case we eventually developed against CVS tip on one of Red Hat's
+SMP machines, and indeed it was unhappy.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 11:42:20 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 21 May 2004 17:42:09 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <40782517171.20040521174209@012.net.il>
+To: Postgresql Performance 
+Subject: PostgreSQL caching
+MIME-Version: 1.0
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+
+Hello,
+
+I have the following problem:
+
+When I run some query after I just run the Postmaster, it takse
+several seconds to execute (sometimes more than 10), if I rerun it
+again afterwards, it takes mere milliseconds.
+
+So, I guess it has to do with PostgreSQL caching.. But how exactly
+does it work? What does it cache? And how can I control it?
+
+I would like to load selected information in the memory before a user
+runs the query. Can I do it somehow? As PostgreSQL is used in my case
+as webserver, it isn't really helping if the user has to wait 10
+seconds every time he goes to a new page (even if refreshing the page
+would be really quick, sine Postgre already loaded the data to
+memory).
+
+P.S If the query or its EXPLAIN are critical for a better
+understanding, let me know.
+
+Regards,
+ Vitaly Belman
+ 
+ ICQ: 1912453
+ AIM: VitalyB1984
+ MSN: tmdagent@hotmail.com
+ Yahoo!: VitalyBe
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 12:30:11 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Fri, 21 May 2004 10:29:34 -0500
+From: "Rosser Schwarz" 
+To: "'Vitaly Belman'" ,
+	"'Postgresql Performance'" 
+Subject: Re: PostgreSQL caching
+Date: Fri, 21 May 2004 10:29:37 -0500
+Message-ID: <002801c43f48$6d629930$2500fa0a@CardServices.TCI.com>
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+
+while you weren't looking, Vitaly Belman wrote:
+
+> So, I guess it has to do with PostgreSQL caching.. But how exactly
+> does it work? What does it cache? And how can I control it?
+
+PostgreSQL uses the operating system's disk cache.  You can hint to
+the postmaster how much memory is available for caching with the
+effective_cache_size directive in your postgresql.conf.  If you're
+running a *nix OS, you can find this by watching `top` for a while;
+in the header, there's a "cached" value (or something to that effect).
+Watching this value, you can determine a rough average and set your
+effective_cache_size to that rough average, or perhaps slightly less.
+I'm not sure how to get this value on Windows.
+
+Pgsql uses the OS's disk cache instead of its own cache management
+because the former is more likely to persist.  If the postmaster
+managed the cache, as soon as the last connection died, the memory
+allocated for caching would be released, and all the cached data
+would be lost.  Relying instead on the OS to cache data means that,
+whether or not there's a postmaster, so long as there has been one,
+there'll be some data cached.
+
+You can "prepopulate" the OS disk cache by periodically running a
+handful of SELECT queries that pull from your most commonly accessed
+tables in a background process.  (A good way of doing that is simply
+to run your most commonly executed SELECTS.)  Those queries should
+take the performance hit of fetching from disk, while your regular
+queries hit the cache.
+
+/rls
+
+--
+Rosser Schwarz
+Total Card, Inc.
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 12:34:48 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 21 May 2004 16:34:12 +0100
+From: Richard Huxton 
+User-Agent: Mozilla Thunderbird 0.6 (X11/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Vitaly Belman 
+Cc: Postgresql Performance 
+Subject: Re: PostgreSQL caching
+References: <40782517171.20040521174209@012.net.il>
+In-Reply-To: <40782517171.20040521174209@012.net.il>
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+
+Vitaly Belman wrote:
+> Hello,
+> 
+> I have the following problem:
+> 
+> When I run some query after I just run the Postmaster, it takse
+> several seconds to execute (sometimes more than 10), if I rerun it
+> again afterwards, it takes mere milliseconds.
+> 
+> So, I guess it has to do with PostgreSQL caching.. But how exactly
+> does it work? What does it cache? And how can I control it?
+
+There are two areas of cache - PostgreSQL's shared buffers and the 
+operating system's disk-cache. You can't directly control what data is 
+cached, it just keeps track of recently used data. It sounds like PG 
+isn't being used for a while so your OS decides to use its cache for 
+webserver files.
+
+> I would like to load selected information in the memory before a user
+> runs the query. Can I do it somehow? As PostgreSQL is used in my case
+> as webserver, it isn't really helping if the user has to wait 10
+> seconds every time he goes to a new page (even if refreshing the page
+> would be really quick, sine Postgre already loaded the data to
+> memory).
+
+If you could "pin" data in the cache it would run quicker, but at the 
+cost of everything else running slower.
+
+Suggested steps:
+1. Read the configuration/tuning guide at:
+   http://www.varlena.com/varlena/GeneralBits/Tidbits/index.php
+2. Post a sample query/explain analyse that runs very slowly when not 
+cached.
+3. If needs be, you can write a simple timed script that performs a 
+query. Or, the autovacuum daemon might be what you want.
+
+
+-- 
+   Richard Huxton
+   Archonet Ltd
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 15:50:37 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <40AE274F.7020800@lulu.com>
+Date: Fri, 21 May 2004 11:59:11 -0400
+From: Bill Montgomery 
+User-Agent: Mozilla Thunderbird 0.5 (X11/20040210)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Subject: Avoiding vacuum full on an UPDATE-heavy table
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+Content-Transfer-Encoding: 7bit
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+
+All,
+
+I have a particularly troublesome table in my 7.3.4 database. It 
+typically has less than 50k rows, and a usage pattern of about 1k 
+INSERTs, 50-100k UPDATEs, and no DELETEs per day. It is vacuumed and 
+analyzed three times per week. However, the performance of queries 
+performed on this table slowly degrades over a period of weeks, until 
+even a "select count(*)" takes several seconds. The only way I've found 
+to restore performance is to VACUUM FULL the table, which is highly 
+undesireable in our application due to the locks it imposes.
+
+Here is the output of a psql session demonstrating the problem/solution. 
+Note the \timing output after each of the SELECTs:
+
+qqqqqqqq=> vacuum analyze xxxx;
+NOTICE:  VACUUM will be committed automatically
+VACUUM
+Time: 715900.74 ms
+qqqqqqqq=> select count(*) from xxxx;
+ count
+-------
+ 17978
+(1 row)
+
+Time: 171789.08 ms
+qqqqqqqq=> vacuum full verbose xxxx;
+NOTICE:  VACUUM will be committed automatically
+INFO:  --Relation public.xxxx--
+INFO:  Pages 188903: Changed 60, reaped 188896, Empty 0, New 0; Tup 
+17987: Vac 1469, Keep/VTL 0/0, UnUsed 9120184, MinLen 92, MaxLen 468; 
+Re-using: Free/Avail. Space 1504083956/1504083872; EndEmpty/Avail. Pages 
+0/188901.
+        CPU 6.23s/1.07u sec elapsed 55.02 sec.
+INFO:  Index xxxx_yyyy_idx: Pages 29296; Tuples 17987: Deleted 1469.
+        CPU 1.08s/0.20u sec elapsed 61.68 sec.
+INFO:  Index xxxx_zzzz_idx: Pages 18412; Tuples 17987: Deleted 1469.
+        CPU 0.67s/0.05u sec elapsed 17.90 sec.
+INFO:  Rel xxxx: Pages: 188903 --> 393; Tuple(s) moved: 17985.
+        CPU 15.97s/19.11u sec elapsed 384.49 sec.
+INFO:  Index xxxx_yyyy_idx: Pages 29326; Tuples 17987: Deleted 17985.
+        CPU 1.14s/0.65u sec elapsed 32.34 sec.
+INFO:  Index xxxx_zzzz_idx: Pages 18412; Tuples 17987: Deleted 17985.
+        CPU 0.43s/0.32u sec elapsed 13.37 sec.
+VACUUM
+Time: 566313.54 ms
+qqqqqqqq=> select count(*) from xxxx;
+ count
+-------
+ 17987
+(1 row)
+
+Time: 22.82 ms
+
+
+Is there any way to avoid doing a periodic VACUUM FULL on this table, 
+given the fairly radical usage pattern? Or is the (ugly) answer to 
+redesign our application to avoid this usage pattern?
+
+Also, how do I read the output of VACUUM FULL? 
+http://www.postgresql.org/docs/7.3/interactive/sql-vacuum.html does not 
+explain how to interpret the output, nor has google helped. I have a 
+feeling that the full vacuum is compressing hundreds of thousands of 
+pages of sparse data into tens of thousands of pages of dense data, thus 
+reducing the number of block reads by an order of magnitude, but I'm not 
+quite sure how to read the output.
+
+FWIW, this is last night's relevant output from the scheduled VACUUM 
+ANALYZE. 24 days have passed since the VACUUM FULL above:
+
+INFO:  --Relation public.xxx--
+INFO:  Index xxx_yyy_idx: Pages 30427; Tuples 34545: Deleted 77066.
+        CPU 1.88s/0.51u sec elapsed 95.39 sec.
+INFO:  Index xxx_zzz_idx: Pages 19049; Tuples 34571: Deleted 77066.
+        CPU 0.83s/0.40u sec elapsed 27.92 sec.
+INFO:  Removed 77066 tuples in 3474 pages.
+        CPU 0.38s/0.32u sec elapsed 1.33 sec.
+INFO:  Pages 13295: Changed 276, Empty 0; Tup 34540: Vac 77066, Keep 0, 
+UnUsed 474020.
+        Total CPU 3.34s/1.29u sec elapsed 125.00 sec.
+INFO:  Analyzing public.xxx
+
+
+Best Regards,
+
+Bill Montgomery
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 15:20:14 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+From: Chris Browne 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: PostgreSQL caching
+Date: Fri, 21 May 2004 13:22:50 -0400
+Organization: cbbrowne Computing Inc
+Lines: 41
+Message-ID: <604qq9hez9.fsf@dev6.int.libertyrms.info>
+References: <40782517171.20040521174209@012.net.il>
+	<40AE2174.7060107@archonet.com>
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+
+dev@archonet.com (Richard Huxton) writes:
+> If you could "pin" data in the cache it would run quicker, but at the
+> cost of everything else running slower.
+>
+> Suggested steps:
+> 1. Read the configuration/tuning guide at:
+>    http://www.varlena.com/varlena/GeneralBits/Tidbits/index.php
+> 2. Post a sample query/explain analyse that runs very slowly when not
+> cached.
+> 3. If needs be, you can write a simple timed script that performs a
+> query. Or, the autovacuum daemon might be what you want.
+
+I don't think this case will be anywhere near so simple to resolve.
+
+I have seen this phenomenon occur when a query needs to pull a
+moderate number of blocks into memory to satisfy a query that involves
+some moderate number of rows.
+
+Let's say you need 2000 rows, which fit into 400 blocks.
+
+The first time the query runs, it needs to pull those 400 blocks off
+disk, which requires 400 reads of 8K of data.  That can easily take a
+few seconds of I/O.
+
+The second time, not only are those blocks cached, they are probably
+cached in the buffer cache, so that the I/O overhead disappears.
+
+There's very likely no problem with the table statistics; they are
+leading to the right query plan, which happens to need to do 5 seconds
+of I/O to pull the data into memory.
+
+What is essentially required is the "prescient cacheing algorithm,"
+where the postmaster must consult /dev/esp in order to get a
+prediction of what blocks it may need to refer to in the next sixty
+seconds.
+-- 
+(format nil "~S@~S" "cbbrowne" "cbbrowne.com")
+http://cbbrowne.com/info/linuxdistributions.html
+"Normally, we don't do people's homework around here, but Venice is a
+very beautiful city, so I'll make a small exception."
+--- Robert Redelmeier compromises his principles
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 14:33:56 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Fri, 21 May 2004 20:33:37 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <20792805375.20040521203337@012.net.il>
+To: Richard Huxton ,
+	Rosser Schwarz 
+Cc: Postgresql Performance 
+Subject: Re: PostgreSQL caching
+In-Reply-To: <40AE2174.7060107@archonet.com>
+References: <40782517171.20040521174209@012.net.il>
+	<40AE2174.7060107@archonet.com>
+MIME-Version: 1.0
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+
+Hello Richard and Rosser,
+
+Thank you both for the answers.
+
+I tried creating a semi cache by running all the queries and indeed it
+worked and I might use such way in the future if needed, yet though, I
+can't help but to feel it isn't exactly the right way to work around
+this problem. If I do, I might as well increase the effective_cache
+value as pointed by the config docs.
+
+Also on this subject, previously I was only fighting with queries that
+run poorly even if you run them 10 days in the row.. They don't seem
+to be cached at all. Does it cahce the query result? If so, it should
+make any query run almost immediately the second time. If it doesn't
+cache the actual result, what does it cache?
+
+If you'll be so kind though, I'd be glad if you could spot anything to
+speed up in this query. Here's the query and its plan that happens
+without any caching:
+
+-------------------------------------------------------------------------------------------------------------
+QUERY
+-----
+SELECT     bv_books. * ,
+           vote_avg, 
+           vote_count 
+FROM       bv_bookgenres, 
+           bv_books 
+WHERE      bv_books.book_id = bv_bookgenres.book_id AND 
+           bv_bookgenres.genre_id = 5830
+ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0; 
+ 
+QUERY PLAN
+----------
+Limit  (cost=2337.41..2337.43 rows=10 width=76) (actual time=7875.000..7875.000 rows=10 loops=1)
+  ->  Sort  (cost=2337.41..2337.94 rows=214 width=76) (actual time=7875.000..7875.000 rows=10 loops=1)
+        Sort Key: bv_books.vote_avg
+        ->  Nested Loop  (cost=0.00..2329.13 rows=214 width=76) (actual time=16.000..7844.000 rows=1993 loops=1)
+              ->  Index Scan using i_bookgenres_genre_id on bv_bookgenres  (cost=0.00..1681.54 rows=214 width=4) (actual time=16.000..3585.000 rows=1993 loops=1)
+                    Index Cond: (genre_id = 5830)
+              ->  Index Scan using bv_books_pkey on bv_books  (cost=0.00..3.01 rows=1 width=76) (actual time=2.137..2.137 rows=1 loops=1993)
+                    Index Cond: (bv_books.book_id = "outer".book_id)
+Total runtime: 7875.000 ms
+-------------------------------------------------------------------------------------------------------------
+
+Some general information:
+
+bv_books holds 17000 rows.
+bv_bookgenres holds 938797 rows.
+
+Using the WHERE (genre_id == 5838) it cuts the number of book_ids to
+around 2000.
+
+As far as indexes are concerned, there's an index on all the rows
+mentioned in the query (as can be seen from the explain), including
+the vote_avg row.
+
+Thanks and regards,
+ Vitaly Belman
+ 
+ ICQ: 1912453
+ AIM: VitalyB1984
+ MSN: tmdagent@hotmail.com
+ Yahoo!: VitalyBe
+
+Friday, May 21, 2004, 6:34:12 PM, you wrote:
+
+RH> Vitaly Belman wrote:
+>> Hello,
+>> 
+>> I have the following problem:
+>> 
+>> When I run some query after I just run the Postmaster, it takse
+>> several seconds to execute (sometimes more than 10), if I rerun it
+>> again afterwards, it takes mere milliseconds.
+>> 
+>> So, I guess it has to do with PostgreSQL caching.. But how exactly
+>> does it work? What does it cache? And how can I control it?
+
+RH> There are two areas of cache - PostgreSQL's shared buffers and the
+RH> operating system's disk-cache. You can't directly control what data is
+RH> cached, it just keeps track of recently used data. It sounds like PG
+RH> isn't being used for a while so your OS decides to use its cache for
+RH> webserver files.
+
+>> I would like to load selected information in the memory before a user
+>> runs the query. Can I do it somehow? As PostgreSQL is used in my case
+>> as webserver, it isn't really helping if the user has to wait 10
+>> seconds every time he goes to a new page (even if refreshing the page
+>> would be really quick, sine Postgre already loaded the data to
+>> memory).
+
+RH> If you could "pin" data in the cache it would run quicker, but at the
+RH> cost of everything else running slower.
+
+RH> Suggested steps:
+RH> 1. Read the configuration/tuning guide at:
+RH>    http://www.varlena.com/varlena/GeneralBits/Tidbits/index.php
+RH> 2. Post a sample query/explain analyse that runs very slowly when not
+RH> cached.
+RH> 3. If needs be, you can write a simple timed script that performs a
+RH> query. Or, the autovacuum daemon might be what you want.
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 15:34:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Subject: Re: PostgreSQL caching
+From: Rod Taylor 
+To: Chris Browne 
+Cc: Postgresql Performance 
+In-Reply-To: <604qq9hez9.fsf@dev6.int.libertyrms.info>
+References: <40782517171.20040521174209@012.net.il>
+	<40AE2174.7060107@archonet.com>
+	<604qq9hez9.fsf@dev6.int.libertyrms.info>
+Content-Type: text/plain
+Message-Id: <1085164433.20081.265.camel@jester>
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+
+> What is essentially required is the "prescient cacheing algorithm,"
+> where the postmaster must consult /dev/esp in order to get a
+> prediction of what blocks it may need to refer to in the next sixty
+> seconds.
+
+Easy enough. Television does it all the time with live shows. The guy
+with the buzzer always seems to know what will be said before they say
+it. All we need is a 5 to 10 second delay...
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 16:02:57 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 21 May 2004 15:02:32 -0400
+From: Neil Conway 
+User-Agent: Mozilla Thunderbird 0.6 (Macintosh/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Rosser Schwarz 
+Cc: 'Vitaly Belman' ,
+	'Postgresql Performance' 
+Subject: Re: PostgreSQL caching
+References: <002801c43f48$6d629930$2500fa0a@CardServices.TCI.com>
+In-Reply-To: <002801c43f48$6d629930$2500fa0a@CardServices.TCI.com>
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+
+Rosser Schwarz wrote:
+> PostgreSQL uses the operating system's disk cache.
+
+... in addition to its own buffer cache, which is stored in shared 
+memory. You're correct though, in that the best practice is to keep the 
+PostgreSQL cache small and give more memory to the operating system's 
+disk cache.
+
+> Pgsql uses the OS's disk cache instead of its own cache management
+> because the former is more likely to persist.  If the postmaster
+> managed the cache, as soon as the last connection died, the memory
+> allocated for caching would be released, and all the cached data
+> would be lost.
+
+No; the cache is stored in shared memory. It wouldn't persist over 
+postmaster restarts (without some scheme of saving and restoring it), 
+but that has nothing to do with why the OS disk cache is usually kept 
+larger than the PG shared buffer cache.
+
+-Neil
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 16:23:03 2004
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+References: <40AE274F.7020800@lulu.com>
+Date: Fri, 21 May 2004 15:22:40 -0400 (EDT)
+Subject: Re: Avoiding vacuum full on an UPDATE-heavy table
+From: "Matthew T. O'Connor" 
+To: "Bill Montgomery" 
+Cc: pgsql-performance@postgresql.org
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+
+> Is there any way to avoid doing a periodic VACUUM FULL on this table,
+> given the fairly radical usage pattern? Or is the (ugly) answer to
+> redesign our application to avoid this usage pattern?
+
+Yes, you should be able to doing avoid periodic VACUUM FULL.  The problem
+is that your table needs to be vacuumed MUCH more often.  What should
+happen is that assuming you have enough FSM space allocated and assuming
+you vacuum the "right" amount, your table will reach a steady state size. 
+As you could see your from you vacumm verbose output your table was almost
+entriely dead space.
+
+pg_autovacuum would probably help as it monitors activity and vacuumus
+tables accordingly.  It is not included with 7.3.x but if you download it
+and compile yourself it will work against a 7.3.x server.
+
+Good luck,
+
+Matthew
+
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 17:11:17 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 21 May 2004 14:10:56 -0600
+From: Marty Scholes 
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+
+Not knowing a whole lot about the internals of Pg, one thing jumped out 
+at me, that each trip to get data from bv_books took 2.137 ms, which 
+came to over 4.2 seconds right there.
+
+The problem "seems" to be the 1993 times that the nested loop spins, as 
+almost all of the time is spent there.
+
+Personally, I am amazed that it takes 3.585 seconds to index scan 
+i_bookgenres_genre_id.  Is that a composite index?  Analyzing the 
+taables may help, as the optimizer appears to mispredict the number of 
+rows returned.
+
+I would be curious to see how it performs with an "IN" clause, which I 
+would suspect would go quite a bit fasrer.  Try the following:
+
+SELECT     bv_books. * ,
+            vote_avg,
+            vote_count
+FROM       bv_bookgenres,
+            bv_books
+WHERE      bv_books.book_id IN (
+               SELECT book_id
+               FROM bv_genres
+               WHERE bv_bookgenres.genre_id = 5830
+               )
+AND bv_bookgenres.genre_id = 5830
+ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0;
+
+In this query, all of the book_id values are pulled at once.
+
+Who knows?
+
+If you get statisctics on this, please post.
+
+Marty
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 17:36:40 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+To: pgsql-performance@postgresql.org
+Path: not-for-mail
+From: Vivek Khera 
+Newsgroups: ml.postgres.performance
+Subject: Re: Avoiding vacuum full on an UPDATE-heavy table
+Date: Fri, 21 May 2004 16:36:18 -0400
+Organization: Khera Communications, Inc., Rockville, MD
+Lines: 18
+Message-ID: 
+References: <40AE274F.7020800@lulu.com>
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+
+>>>>> "BM" == Bill Montgomery  writes:
+
+BM> Is there any way to avoid doing a periodic VACUUM FULL on this table,
+BM> given the fairly radical usage pattern? Or is the (ugly) answer to
+BM> redesign our application to avoid this usage pattern?
+
+I'll bet upgrading to 7.4.2 clears up your problems.  I'm not sure if
+it was in 7.3 or 7.4 where the index bloat problem was solved.  Try to
+see if just reindexing will help your performance.  Also, run a plain
+vacuum at least nightly so that your table size stays reasonable.  It
+won't take much time on a table with only 50k rows in it.
+
+
+-- 
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
+Vivek Khera, Ph.D.                Khera Communications, Inc.
+Internet: khera@kciLink.com       Rockville, MD  +1-301-869-4449 x806
+AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 18:32:22 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Fri, 21 May 2004 17:29:33 -0400
+From: Bill Montgomery 
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+To: pgsql-performance@postgresql.org
+Subject: Re: Avoiding vacuum full on an UPDATE-heavy table
+References: <40AE274F.7020800@lulu.com>
+	<54139.192.154.91.225.1085167360.squirrel@192.154.91.225>
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+
+Matthew T. O'Connor wrote:
+
+>>Is there any way to avoid doing a periodic VACUUM FULL on this table,
+>>given the fairly radical usage pattern? Or is the (ugly) answer to
+>>redesign our application to avoid this usage pattern?
+>>    
+>>
+>pg_autovacuum would probably help as it monitors activity and vacuumus
+>tables accordingly.  It is not included with 7.3.x but if you download it
+>and compile yourself it will work against a 7.3.x server.
+>  
+>
+As a quick fix, since we're upgrading to 7.4.2 in a few weeks anyhow 
+(which includes pg_autovacuum), I've simply set up an hourly vacuum on 
+this table. It only takes ~4 seconds to execute when kept up on an 
+hourly basis. Is there any penalty to vacuuming too frequently, other 
+than the time wasted in an unnecessary vacuum operation?
+
+My hourly VACUUM VERBOSE output now looks like this:
+
+INFO:  --Relation public.xxxx--
+INFO:  Index xxxx_yyyy_idx: Pages 30452; Tuples 34990: Deleted 1226.
+        CPU 0.67s/0.18u sec elapsed 0.87 sec.
+INFO:  Index xxxx_yyyy_idx: Pages 19054; Tuples 34991: Deleted 1226.
+        CPU 0.51s/0.13u sec elapsed 1.35 sec.
+INFO:  Removed 1226 tuples in 137 pages.
+        CPU 0.01s/0.00u sec elapsed 1.30 sec.
+INFO:  Pages 13709: Changed 31, Empty 0; Tup 34990: Vac 1226, Keep 0, 
+UnUsed 567233.
+        Total CPU 1.58s/0.31u sec elapsed 3.91 sec.
+INFO:  Analyzing public.xxxx
+VACUUM
+
+With regards to Vivek's post about index bloat, I tried REINDEXing 
+before I did a VACUUM FULL a month ago when performance had gotten 
+dismal. It didn't help :-(
+
+Best Regards,
+
+Bill Montgomery
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 19:09:44 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Fri, 21 May 2004 18:09:24 -0400 (EDT)
+To: Bill Montgomery 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Avoiding vacuum full on an UPDATE-heavy table 
+In-reply-to: <40AE274F.7020800@lulu.com> 
+References: <40AE274F.7020800@lulu.com>
+Comments: In-reply-to Bill Montgomery 
+	message dated "Fri, 21 May 2004 11:59:11 -0400"
+Date: Fri, 21 May 2004 18:09:24 -0400
+Message-ID: <16535.1085177364@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Bill Montgomery  writes:
+> I have a particularly troublesome table in my 7.3.4 database. It 
+> typically has less than 50k rows, and a usage pattern of about 1k 
+> INSERTs, 50-100k UPDATEs, and no DELETEs per day. It is vacuumed and 
+> analyzed three times per week.
+
+You probably want to vacuum (non-FULL) once a day, if not more often.
+Also take a look at your FSM settings --- it seems like a good bet that
+they're not large enough to remember all the free space in your
+database.
+
+With adequate FSM the table should stabilize at a physical size
+corresponding to number-of-live-rows + number-of-updates-between-VACUUMs, 
+which would be three times the minimum possible size if you vacuum once
+a day (50K + 100K) or five times if you stick to every-other-day
+(50K + 200K).  Your VACUUM FULL output shows that the table had bloated
+to hundreds of times the minimum size:
+
+> INFO:  Rel xxxx: Pages: 188903 --> 393; Tuple(s) moved: 17985.
+
+and AFAIK the only way that will happen is if you fail to vacuum at all
+or don't have enough FSM.
+
+The indexes are looking darn large as well.  In 7.3 about the only thing
+you can do about this is REINDEX the table every so often.  7.4 should
+behave better though.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 20:23:57 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <40AE8F78.2070901@drivefaster.net>
+Date: Fri, 21 May 2004 17:23:36 -0600
+From: Dan Harris 
+User-Agent: Mozilla Thunderbird 0.6 (Macintosh/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Subject: tuning for AIX 5L with large memory
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+Content-Transfer-Encoding: 7bit
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+
+I will soon have at my disposal a new IBM pSeries server.  The main 
+mission for this box will be to serve several  pg databases.  I have 
+ordered 8GB of RAM and want to learn the best way to tune pg and AIX for 
+this configuration.  Specifically, I am curious about shared memory 
+limitations.  I've had to tune the shmmax on linux machines before but 
+I'm new to AIX and not sure if this is even required on that platform?  
+Google has not been much help for specifics here. 
+
+Hoping someone else here has a similar platform and can offer some advice..
+
+Thanks!
+
+-Dan Harris
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 23:20:16 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	for pgsql-performance@postgresql.org; Sat, 22 May 2004 01:50:21 GMT
+From: Christopher Browne 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: tuning for AIX 5L with large memory
+Date: Fri, 21 May 2004 21:28:08 -0400
+Organization: cbbrowne Computing Inc
+Lines: 40
+Message-ID: 
+References: <40AE8F78.2070901@drivefaster.net>
+Mime-Version: 1.0
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+ Obscurity,
+	linux)
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+To: pgsql-performance@postgresql.org
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+
+Clinging to sanity, fbsd@drivefaster.net (Dan Harris) mumbled into her beard:
+> I will soon have at my disposal a new IBM pSeries server.  The main
+> mission for this box will be to serve several pg databases.  I have
+> ordered 8GB of RAM and want to learn the best way to tune pg and AIX
+> for this configuration.  Specifically, I am curious about shared
+> memory limitations.  I've had to tune the shmmax on linux machines
+> before but I'm new to AIX and not sure if this is even required on
+> that platform?  Google has not been much help for specifics here.
+>
+> Hoping someone else here has a similar platform and can offer some advice..
+
+We have a couple of these at work; they're nice and fast, although the
+process of compiling things, well, "makes me feel a little unclean."
+
+One of our sysadmins did all the "configuring OS stuff" part; I don't
+recall offhand if there was a need to twiddle something in order to
+get it to have great gobs of shared memory.
+
+A quick Google on this gives me the impression that AIX supports, out
+of the box, multiple GB of shared memory without special kernel
+configuration.  A DB/2 configuration guide tells users of Solaris and
+HP/UX that they need to set shmmax in sundry config files and reboot.
+No such instruction for AIX.
+
+If it needs configuring, it's probably somewhere in SMIT.  And you can
+always try starting up an instance to see how big it'll let you make
+shared memory.
+
+The usual rule of thumb has been that having substantially more than
+10000 blocks worth of shared memory is unworthwhile.  I don't think
+anyone has done a detailed study on AIX to see if bigger numbers play
+well or not.  I would think that having more than about 1 to 1.5GB of
+shared memory in use for buffer cache would start playing badly, but I
+have no numbers.
+-- 
+select 'cbbrowne' || '@' || 'cbbrowne.com';
+http://www3.sympatico.ca/cbbrowne/sap.html
+Would-be National Mottos:
+USA: "We don't care where you come from.  We can't find our *own*
+country on a map..."
+
+From pgsql-performance-owner@postgresql.org  Fri May 21 23:31:44 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Fri, 21 May 2004 22:31:15 -0400
+From: Neil Conway 
+User-Agent: Mozilla Thunderbird 0.6 (Macintosh/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Christopher Browne 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: tuning for AIX 5L with large memory
+References: <40AE8F78.2070901@drivefaster.net>
+	
+In-Reply-To: 
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+
+Christopher Browne wrote:
+> One of our sysadmins did all the "configuring OS stuff" part; I don't
+> recall offhand if there was a need to twiddle something in order to
+> get it to have great gobs of shared memory.
+
+FWIW, the section on configuring kernel resources under various 
+Unixen[1] doesn't have any documentation for AIX. If someone out there 
+knows which knobs need to be tweaked, would they mind sending in a doc 
+patch? (Or just specifying what needs to be done, and I'll add the SGML.)
+
+-Neil
+
+[1] 
+http://developer.postgresql.org/docs/postgres/kernel-resources.html#SYSVIPC
+
+From pgsql-performance-owner@postgresql.org  Sun May 23 03:25:13 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Sun, 23 May 2004 01:22:09 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <188896456515.20040523012209@012.net.il>
+To: Marty Scholes 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+In-Reply-To: <40AE6250.6070904@outputservices.com>
+References: <40AE6250.6070904@outputservices.com>
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
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+X-Sequence-Number: 7026
+
+Hello Marty,
+
+MS> Is that a composite index?
+
+It is a regular btree index. What is a composite index?
+
+MS> Analyzing the taables may help, as the optimizer appears to
+MS> mispredict the number of rows returned.
+
+I'll try analyzing, but I highly doubt that it would help. I analyzed
+once already and haven't changed the data since.
+
+MS> I would be curious to see how it performs with an "IN" clause,
+MS> which I would suspect would go quite a bit fasrer.
+
+Actually it reached 20s before I canceled it... Here's the explain:
+
+QUERY PLAN
+Limit  (cost=3561.85..3561.88 rows=10 width=76)
+  ->  Sort  (cost=3561.85..3562.39 rows=214 width=76)
+        Sort Key: bv_books.vote_avg
+        ->  Nested Loop  (cost=1760.75..3553.57 rows=214 width=76)
+              ->  Index Scan using i_bookgenres_genre_id on bv_bookgenres  (cost=0.00..1681.54 rows=214 width=0)
+                    Index Cond: (genre_id = 5830)
+              ->  Materialize  (cost=1760.75..1761.01 rows=26 width=76)
+                    ->  Nested Loop  (cost=1682.07..1760.75 rows=26 width=76)
+                          ->  HashAggregate  (cost=1682.07..1682.07 rows=26 width=4)
+                                ->  Index Scan using i_bookgenres_genre_id on bv_bookgenres  (cost=0.00..1681.54 rows=214 width=4)
+                                      Index Cond: (genre_id = 5830)
+                          ->  Index Scan using bv_books_pkey on bv_books  (cost=0.00..3.01 rows=1 width=76)
+                                Index Cond: (bv_books.book_id = "outer".book_id)
+
+                                
+Thank you for your try.
+
+Regards,
+Vitaly Belman
+ 
+ ICQ: 1912453
+ AIM: VitalyB1984
+ MSN: tmdagent@hotmail.com
+ Yahoo!: VitalyBe
+
+Friday, May 21, 2004, 11:10:56 PM, you wrote:
+
+MS> Not knowing a whole lot about the internals of Pg, one thing jumped out
+MS> at me, that each trip to get data from bv_books took 2.137 ms, which
+MS> came to over 4.2 seconds right there.
+
+MS> The problem "seems" to be the 1993 times that the nested loop spins, as
+MS> almost all of the time is spent there.
+
+MS> Personally, I am amazed that it takes 3.585 seconds to index scan 
+MS> i_bookgenres_genre_id.  Is that a composite index?  Analyzing the 
+MS> taables may help, as the optimizer appears to mispredict the number of
+MS> rows returned.
+
+MS> I would be curious to see how it performs with an "IN" clause, which I
+MS> would suspect would go quite a bit fasrer.  Try the following:
+
+MS> SELECT     bv_books. * ,
+MS>             vote_avg,
+MS>             vote_count
+MS> FROM       bv_bookgenres,
+MS>             bv_books
+MS> WHERE      bv_books.book_id IN (
+MS>                SELECT book_id
+MS>                FROM bv_genres
+MS>                WHERE bv_bookgenres.genre_id = 5830
+MS>                )
+MS> AND bv_bookgenres.genre_id = 5830
+MS> ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0;
+
+MS> In this query, all of the book_id values are pulled at once.
+
+MS> Who knows?
+
+MS> If you get statisctics on this, please post.
+
+MS> Marty
+
+
+MS> ---------------------------(end of
+MS> broadcast)---------------------------
+MS> TIP 4: Don't 'kill -9' the postmaster
+
+
+From pgsql-performance-owner@postgresql.org  Sun May 23 03:55:56 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Sat, 22 May 2004 21:30:25 -0600
+From: Dan Harris 
+User-Agent: Mozilla Thunderbird 0.5 (Windows/20040207)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+Cc: pgsql-performance@postgresql.org
+Subject: Re: tuning for AIX 5L with large memory
+References: <40AE8F78.2070901@drivefaster.net>
+	
+In-Reply-To: 
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+
+Christopher Browne wrote:
+
+>We have a couple of these at work; they're nice and fast, although the
+>process of compiling things, well, "makes me feel a little unclean."
+>
+>
+>  
+>
+Thanks very much for your detailed reply, Christopher.  Would you mind 
+elaborating on the "makes me feel a little unclean" statement? Also, I'm 
+curious which models you are running and if you have any anecdotal 
+comparisons for perfomance?  I'm completely unfamiliar with AIX, so if 
+there are dark corners that await me, I'd love to hear a little more so 
+I can be prepared.  I'm going out on a limb here and jumping to an 
+unfamiliar architecture as well as OS, but the IO performance of these 
+systems has convinced me that it's what I need to break out of my I/O 
+limited x86 systems.
+
+I suppose when I do get it, I'll just experiment with different sizes of 
+shared memory and run some benchmarks.  For the price of these things, 
+they better be some good marks!
+
+Thanks again
+
+-Dan Harris
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 13:51:36 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 24 May 2004 09:51:12 PDT
+Date: Mon, 24 May 2004 09:51:12 -0700 (PDT)
+From: Litao Wu 
+Subject: index's relpages after table analyzed
+To: pgsql-performance@postgresql.org
+In-Reply-To: <16535.1085177364@sss.pgh.pa.us>
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+
+Hi, 
+
+After a table analyzed a table, the table's relpages 
+of pg_class gets updated, but not those of associated 
+indexes, which can be updated by "vacuum analyze".
+
+Is this a feature or a bug?
+
+I have some tables and there are almost only
+inserts. So I do not care about the "dead tuples",
+but do care about the statistics. 
+
+Does the above "future/bug" affect the performance?
+
+My PG version is 7.3.2.
+
+Thanks,
+
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+Yahoo! Domains � Claim yours for only $14.70/year
+http://smallbusiness.promotions.yahoo.com/offer 
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 14:21:18 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 24 May 2004 10:20:56 PDT
+Date: Mon, 24 May 2004 10:20:56 -0700 (PDT)
+From: Litao Wu 
+Subject: Re: index's relpages after table analyzed
+To: Litao Wu , pgsql-performance@postgresql.org
+In-Reply-To: <20040524165112.72633.qmail@web13126.mail.yahoo.com>
+MIME-Version: 1.0
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+
+>From PG
+http://developer.postgresql.org/docs/postgres/diskusage.html:
+
+"(Remember, relpages is only updated by VACUUM and
+ANALYZE.)"
+
+
+--- Litao Wu  wrote:
+> Hi, 
+> 
+> After a table analyzed a table, the table's relpages
+> 
+> of pg_class gets updated, but not those of
+> associated 
+> indexes, which can be updated by "vacuum analyze".
+> 
+> Is this a feature or a bug?
+> 
+> I have some tables and there are almost only
+> inserts. So I do not care about the "dead tuples",
+> but do care about the statistics. 
+> 
+> Does the above "future/bug" affect the performance?
+> 
+> My PG version is 7.3.2.
+> 
+> Thanks,
+> 
+> 
+> 
+> 
+> 	
+> 		
+> __________________________________
+> Do you Yahoo!?
+> Yahoo! Domains ?Claim yours for only $14.70/year
+> http://smallbusiness.promotions.yahoo.com/offer 
+> 
+> ---------------------------(end of
+> broadcast)---------------------------
+> TIP 8: explain analyze is your friend
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+Yahoo! Domains � Claim yours for only $14.70/year
+http://smallbusiness.promotions.yahoo.com/offer 
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 16:05:36 2004
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+	with ESMTP id 5185903; Mon, 24 May 2004 12:06:46 -0700
+From: Josh Berkus 
+Reply-To: josh@agliodbs.com
+Organization: Aglio Database Solutions
+To: Litao Wu , pgsql-performance@postgresql.org
+Subject: Re: index's relpages after table analyzed
+Date: Mon, 24 May 2004 12:05:26 -0700
+User-Agent: KMail/1.5.4
+References: <20040524165112.72633.qmail@web13126.mail.yahoo.com>
+In-Reply-To: <20040524165112.72633.qmail@web13126.mail.yahoo.com>
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+
+Litao,
+
+> I have some tables and there are almost only
+> inserts. So I do not care about the "dead tuples",
+> but do care about the statistics. 
+
+Then just run ANALYZE on those tables, and not VACUUM.
+ANALYZE ;
+
+> My PG version is 7.3.2.
+
+I would suggest upgrading to 7.3.6; the version you are using has several 
+known bugs.
+
+-- 
+-Josh Berkus
+ Aglio Database Solutions
+ San Francisco
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 16:09:03 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+From: Josh Berkus 
+Reply-To: josh@agliodbs.com
+Organization: Aglio Database Solutions
+To: Bill Montgomery ,
+	pgsql-performance@postgresql.org
+Subject: Re: Avoiding vacuum full on an UPDATE-heavy table
+Date: Mon, 24 May 2004 12:08:50 -0700
+User-Agent: KMail/1.5.4
+References: <40AE274F.7020800@lulu.com>
+	<54139.192.154.91.225.1085167360.squirrel@192.154.91.225>
+	<40AE74BD.5050802@lulu.com>
+In-Reply-To: <40AE74BD.5050802@lulu.com>
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+
+Bill,
+
+> As a quick fix, since we're upgrading to 7.4.2 in a few weeks anyhow 
+> (which includes pg_autovacuum), I've simply set up an hourly vacuum on 
+> this table. It only takes ~4 seconds to execute when kept up on an 
+> hourly basis. Is there any penalty to vacuuming too frequently, other 
+> than the time wasted in an unnecessary vacuum operation?
+
+Nope, no penalty other than the I/O and CPU load while vacuuming.   If you 
+have a lot of transactions involving serial writes to many tables, sometimes 
+you can get into a deadlock situation, which is annoying, but I wouldn't 
+assume this to be a problem until it crops up.
+
+-- 
+-Josh Berkus
+ Aglio Database Solutions
+ San Francisco
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 16:48:27 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 24 May 2004 12:48:03 PDT
+Date: Mon, 24 May 2004 12:48:03 -0700 (PDT)
+From: Litao Wu 
+Subject: Re: index's relpages after table analyzed
+To: josh@agliodbs.com, pgsql-performance@postgresql.org
+In-Reply-To: <200405241205.26170.josh@agliodbs.com>
+MIME-Version: 1.0
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+
+Hi Josh,
+
+I know that and that is what I am using now.
+The problem is I also need to know
+the relpages each indexe takes and "analyze"
+seems not update relpages though vacuum and
+vacuum analyze do. 
+
+According to PG doc:
+"Remember, relpages is only updated by VACUUM and
+ANALYZE" 
+
+My question is why relpages of indexes
+do not get updated after "analyze".
+
+Here is a quick test:
+create table test as select * from pg_class where 1=2;
+create index test_idx on test (relname);
+insert into test select * from pg_class;
+select relname, relpages from pg_class
+where relname in ('test', 'test_idx');
+ relname  | relpages
+----------+----------
+ test     |       10
+ test_idx |        1
+(2 rows)
+
+analyze test;
+select relname, relpages from pg_class
+where relname in ('test', 'test_idx');
+ relname  | relpages
+----------+----------
+ test     |       27
+ test_idx |        1
+(2 rows)
+-- Analyze only updates table's relpage, not index's!
+
+vacuum analyze test;
+select relname, relpages from pg_class
+where relname in ('test', 'test_idx');
+ relname  | relpages
+----------+----------
+ test     |       27
+ test_idx |       22
+(2 rows)
+-- "acuum analzye" updates both
+-- "vacuum" only also updates both
+
+Thank you for your help!
+
+
+--- Josh Berkus  wrote:
+> Litao,
+> 
+> > I have some tables and there are almost only
+> > inserts. So I do not care about the "dead tuples",
+> > but do care about the statistics. 
+> 
+> Then just run ANALYZE on those tables, and not
+> VACUUM.
+> ANALYZE ;
+> 
+> > My PG version is 7.3.2.
+> 
+> I would suggest upgrading to 7.3.6; the version you
+> are using has several 
+> known bugs.
+> 
+> -- 
+> -Josh Berkus
+>  Aglio Database Solutions
+>  San Francisco
+> 
+
+
+
+	
+		
+__________________________________
+Do you Yahoo!?
+Friends.  Fun.  Try the all-new Yahoo! Messenger.
+http://messenger.yahoo.com/ 
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 19:52:23 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40B27C92.9000109@outputservices.com>
+Date: Mon, 24 May 2004 16:52:02 -0600
+From: Marty Scholes 
+User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:0.9.9) Gecko/20020517
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+
+ > Hello Marty,
+ >
+ > MS> Is that a composite index?
+ >
+ > It is a regular btree index. What is a composite index?
+
+My apologies.  A composite index is one that consists of multiple fields 
+(aka multicolumn index).  The reason I ask is that it was spending 
+almost half the time just searching bv_bookgenres, which seemed odd.
+
+I may be speaking out of turn since I am not overly familiar with Pg's 
+quirks and internals.
+
+A composite index, or any index of a large field, will lower the number 
+of index items stored per btree node, thereby lowering the branching 
+factor and increasing the tree depth.  On tables with many rows, this 
+can result in many more disk accesses for reading the index.  An index 
+btree that is 6 levels deep will require at least seven disk accesses (6 
+for the index, one for the table row) per row retrieved.
+
+Not knowing the structure of the indexes, it's hard to say too much 
+about it.  The fact that a 1993 row select from an indexed table took 
+3.5 seconds caused me to take notice.
+
+ > MS> I would be curious to see how it performs with an "IN" clause,
+ > MS> which I would suspect would go quite a bit fasrer.
+ >
+ > Actually it reached 20s before I canceled it... Here's the explain:
+
+I believe that.  The code I posted had a nasty join bug.  If my math is 
+right, the query was trying to return 1993*1993, or just under 4 million 
+rows.
+
+I didn't see the table structure, but I assume that the vote_avg and 
+vote_count fields are in bv_bookgenres.  If no fields are actually 
+needed from bv_bookgenres, then the query might be constructed in a way 
+that only the index would be read, without loading any row data.
+
+I think that you mentioned this was for a web app.  Do you actually have 
+a web page that displays 2000 rows of data?
+
+Good luck,
+Marty
+
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 22:23:00 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Mon, 24 May 2004 21:22:38 -0400 (EDT)
+To: Litao Wu 
+Cc: josh@agliodbs.com, pgsql-performance@postgresql.org
+Subject: Re: index's relpages after table analyzed 
+In-reply-to: <20040524194803.8970.qmail@web13125.mail.yahoo.com> 
+References: <20040524194803.8970.qmail@web13125.mail.yahoo.com>
+Comments: In-reply-to Litao Wu 
+	message dated "Mon, 24 May 2004 12:48:03 -0700"
+Date: Mon, 24 May 2004 21:22:38 -0400
+Message-ID: <16103.1085448158@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Litao Wu  writes:
+> My question is why relpages of indexes
+> do not get updated after "analyze".
+
+It's an oversight, which just got fixed in CVS tip a few weeks ago.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Mon May 24 23:50:20 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ; Tue, 25 May 2004 10:41:35 +0800
+Message-Id: <200405250241.i4P2fMhv001672@mail.census.gov.ph>
+From: "Michael Ryan S. Puncia" 
+To: 
+Subject: Server process
+Date: Tue, 25 May 2004 10:54:46 +0800
+MIME-Version: 1.0
+Content-Type: multipart/alternative;
+	boundary="----=_NextPart_000_0000_01C44246.B6E5BD70"
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+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0000_01C44246.B6E5BD70
+Content-Type: text/plain;
+	charset="us-ascii"
+Content-Transfer-Encoding: 7bit
+
+Hi,
+
+ 
+
+How can I automatically kill a process in the database (ex a select or
+explain) if it exceeds my limit of 2 or 3 mins ..
+
+ For example : I have a query that already running for 3 or 4 mins I want to
+kill that process for a reason and return a
+
+Signal to the user.
+
+ 
+
+Thanks
+
+Michael 
+
+
+------=_NextPart_000_0000_01C44246.B6E5BD70
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+	charset="us-ascii"
+Content-Transfer-Encoding: quoted-printable
+
+
+
+
+
+
+
+
+
+
+
+
+

+
+
Hi,

+
+
 

+
+
How can I automatically kill a process in the database (=
+ex a
+select or explain) if it exceeds my limit of 2 or 3 mins ..

+
+
 For example : I have a query that already running =
+for
+3 or 4 mins I want to kill that process for a reason and return a

+
+
Signal to the user.

+
+
 

+
+
Thanks

+
+
Michael 

+
+

+
+
+
+
+
+------=_NextPart_000_0000_01C44246.B6E5BD70--
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+
+
+From pgsql-performance-owner@postgresql.org  Tue May 25 00:01:15 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	(envelope-from chriskl@familyhealth.com.au)
+Message-ID: <40B2B801.9020201@familyhealth.com.au>
+Date: Tue, 25 May 2004 11:05:37 +0800
+From: Christopher Kings-Lynne 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: "Michael Ryan S. Puncia" 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Server process
+References: <200405250241.i4P2fMhv001672@mail.census.gov.ph>
+In-Reply-To: <200405250241.i4P2fMhv001672@mail.census.gov.ph>
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+X-Sequence-Number: 7036
+
+Read the docs on going SET statement_timeout TO ...;
+
+Chris
+
+Michael Ryan S. Puncia wrote:
+
+> 
+> 
+> Hi,
+> 
+>  
+> 
+> How can I automatically kill a process in the database (ex a select or 
+> explain) if it exceeds my limit of 2 or 3 mins ..
+> 
+>  For example : I have a query that already running for 3 or 4 mins I 
+> want to kill that process for a reason and return a
+> 
+> Signal to the user.
+> 
+>  
+> 
+> Thanks
+> 
+> Michael
+> 
+
+From pgsql-performance-owner@postgresql.org  Tue May 25 12:38:14 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Tue, 25 May 2004 17:37:45 +0200 (MEST)
+Message-ID: <40B36848.1090403@oli.tudelft.nl>
+Date: Tue, 25 May 2004 17:37:44 +0200
+From: Jochem van Dieten 
+Organization: OnLine Internet
+User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
+	rv:1.6b) Gecko/20031205 Thunderbird/0.4
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Vitaly Belman 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+References: <20792805375.20040521203337@012.net.il>
+Content-Type: text/plain; charset=us-ascii; format=flowed
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+X-Sequence-Number: 7037
+
+Vitaly Belman wrote:
+> 
+> If you'll be so kind though, I'd be glad if you could spot anything to
+> speed up in this query. Here's the query and its plan that happens
+> without any caching:
+> 
+> -------------------------------------------------------------------------------------------------------------
+> QUERY
+> -----
+> SELECT     bv_books. * ,
+>            vote_avg, 
+>            vote_count 
+> FROM       bv_bookgenres, 
+>            bv_books 
+> WHERE      bv_books.book_id = bv_bookgenres.book_id AND 
+>            bv_bookgenres.genre_id = 5830
+> ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0; 
+>  
+> QUERY PLAN
+> ----------
+> Limit  (cost=2337.41..2337.43 rows=10 width=76) (actual time=7875.000..7875.000 rows=10 loops=1)
+>   ->  Sort  (cost=2337.41..2337.94 rows=214 width=76) (actual time=7875.000..7875.000 rows=10 loops=1)
+>         Sort Key: bv_books.vote_avg
+>         ->  Nested Loop  (cost=0.00..2329.13 rows=214 width=76) (actual time=16.000..7844.000 rows=1993 loops=1)
+>               ->  Index Scan using i_bookgenres_genre_id on bv_bookgenres  (cost=0.00..1681.54 rows=214 width=4) (actual time=16.000..3585.000 rows=1993 loops=1)
+>                     Index Cond: (genre_id = 5830)
+>               ->  Index Scan using bv_books_pkey on bv_books  (cost=0.00..3.01 rows=1 width=76) (actual time=2.137..2.137 rows=1 loops=1993)
+>                     Index Cond: (bv_books.book_id = "outer".book_id)
+> Total runtime: 7875.000 ms
+
+Presuming that vote_avg is a field in the table bv_bookgenres, 
+try a composite index on genre_id and vote_avg and then see if 
+you can use the limit clause to reduce the number of loop 
+iterations from 1993 to 10.
+
+CREATE INDEX test_idx ON bv_bookgenres (genre_id, vote_avg);
+
+
+The following query tries to force that execution lan and, 
+presuming there is a foreign key relation between 
+bv_books.book_id AND bv_bookgenres.book_id, I expect it will give 
+the same results, but be carefull with NULL's:
+
+SELECT	bv_books. * ,
+	vote_avg,
+	vote_count
+FROM 	(
+		SELECT	bg.*
+		FROM 	bv_bookgenres bg
+		WHERE	bg.genre_id = 5830
+		ORDER BY
+			bg.vote_avg DESC
+		LIMIT	10
+	) bv_bookgenres,
+	bv_books
+WHERE	bv_books.book_id = bv_bookgenres.book_id
+ORDER BY
+	vote_avg DESC
+LIMIT	10;
+
+Jochem
+
+
+-- 
+I don't get it
+immigrants don't work
+and steal our jobs
+     - Loesje
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 28 20:57:00 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	Tue, 25 May 2004 11:37:55 -0700 (PDT)
+Message-ID: 
+Date: Tue, 25 May 2004 11:37:55 -0700
+From: Josh Sacks 
+To: pgsql-performance@postgresql.org
+Subject: Not using Primary Key in query
+Mime-Version: 1.0
+Content-Type: text/plain; charset=US-ASCII
+Content-Transfer-Encoding: 7bit
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Sequence-Number: 7053
+
+I can't understand what's going on in this simple query:
+
+select c.name from Candidate C where
+  C.candidate_id in (select candidate_id from REFERRAL R
+                     where  r.employee_id = 3000);
+
+
+Where Candidate.CANDIDATE_ID is the primary key for Candidate.
+Here's the EXPLAN ANALYZE:
+
+Seq Scan on candidate c  (cost=100000000.00..100705078.06 rows=143282 width=18) 
+                                    (actual time=2320.01..2320.01
+rows=0 loops=1)
+   Filter: (subplan)
+   SubPlan
+     ->  Materialize  (cost=2.42..2.42 rows=3 width=4) 
+                           (actual time=0.00..0.00 rows=0 loops=286563)
+           ->  Index Scan using referral_employee_id_index on referral r  
+                   (cost=0.00..2.42 rows=3 width=4) (actual
+time=0.48..0.48 rows=0 loops=1)
+                 Index Cond: (employee_id = 3000)
+
+
+It seems to be accurately estimating the number of rows returned by
+the sub-query (3), but then it thinks that 143282 rows are going to be
+returned by the main query, even though we are querying based on the
+PRIMARY KEY!
+
+
+To prove that in index query is possible, I tried:
+select c.name from Candidate C where
+  C.candidate_id in (99, 22, 23123, 2344)  which resulted in:
+
+Index Scan using candidate_id_index, candidate_id_index,
+candidate_id_index, candidate_id_index on candidate c
+     (cost=0.00..17.52 rows=4 width=18) (actual time=24.437..29.088
+rows=3 loops=1)
+   Index Cond:
+    ((candidate_id = 99) OR (candidate_id = 22) OR 
+      (candidate_id = 23123) OR (candidate_id = 2344))
+
+
+Any ideas what's causing the query planner to make such a simple and
+drastic error?
+
+Thanks,
+Josh
+
+From pgsql-performance-owner@postgresql.org  Tue May 25 16:53:13 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	sender ; 25 May 2004 22:53:05 +0300
+Date: Tue, 25 May 2004 22:53:05 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <1371146711781.20040525225305@012.net.il>
+To: Jochem van Dieten ,
+	Marty Scholes 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+In-Reply-To: <40B36848.1090403@oli.tudelft.nl>
+References: <20792805375.20040521203337@012.net.il>
+	<40B36848.1090403@oli.tudelft.nl>
+MIME-Version: 1.0
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+X-Sequence-Number: 7038
+
+Hello Jochem and Marty,
+
+I guess I should have posted the table structure before =(:
+
+Table structure + Indexes
+-------------------------
+
+CREATE TABLE public.bv_books
+(
+  book_id serial NOT NULL,
+  book_title varchar(255) NOT NULL,
+  series_id int4,
+  series_index int2,
+  annotation_desc_id int4,
+  description_desc_id int4,
+  book_picture varchar(255) NOT NULL,
+  vote_avg float4 NOT NULL,
+  vote_count int4 NOT NULL,
+  CONSTRAINT bv_books_pkey PRIMARY KEY (book_id)
+) WITH OIDS;
+
+CREATE INDEX i_books_vote_avg
+  ON public.bv_books
+  USING btree
+  (vote_avg);
+
+CREATE INDEX i_books_vote_count
+  ON public.bv_books
+  USING btree
+  (vote_count);
+
+-------------------------
+
+CREATE TABLE public.bv_bookgenres
+(
+  book_id int4 NOT NULL,
+  genre_id int4 NOT NULL,
+  CONSTRAINT bv_bookgenres_pkey PRIMARY KEY (book_id, genre_id),
+  CONSTRAINT fk_bookgenres_book_id FOREIGN KEY (book_id) REFERENCES public.bv_books (book_id) ON UPDATE RESTRICT ON DELETE RESTRICT
+) WITH OIDS;
+
+CREATE INDEX i_bookgenres_book_id
+  ON public.bv_bookgenres
+  USING btree
+  (book_id);
+
+CREATE INDEX i_bookgenres_genre_id
+  ON public.bv_bookgenres
+  USING btree
+  (genre_id);
+-------------------------
+
+MS> I didn't see the table structure, but I assume that the vote_avg and
+MS> vote_count fields are in bv_bookgenres.  If no fields are actually 
+MS> needed from bv_bookgenres, then the query might be constructed in a way 
+MS> that only the index would be read, without loading any row data.
+
+I didn't understand you. vote_avg is stored in bv_books.. So yes, the
+only thing I need from bv_bookgenres is the id of the book, but I can't
+store this info in bv_books because there is N to N relationship
+between them - every book can belong to a number of genres... If
+that's what you meant.
+
+MS> I think that you mentioned this was for a web app.  Do you actually have
+MS> a web page that displays 2000 rows of data?
+
+Well.. It is all "paginated", you can access 2000 items of the data
+(as there are actually 2000 books in the genre) but you only see 10
+items at a time.. I mean, probably no one would go over the 2000
+books, but I can't just hide them =\.
+
+JvD> Presuming that vote_avg is a field in the table bv_bookgenres,
+JvD> try a composite index on genre_id and vote_avg and then see if 
+JvD> you can use the limit clause to reduce the number of loop 
+JvD> iterations from 1993 to 10.
+
+I'm afraid your idea is invalid in my case =\... Naturally I could
+eventually do data coupling to gain perforemnce boost if this issue
+will not be solved in other ways. I'll keep your idea in mind anyway,
+thanks.
+
+Once again thanks for you feedback.
+
+Regards,
+ Vitaly Belman
+ 
+ ICQ: 1912453
+ AIM: VitalyB1984
+ MSN: tmdagent@hotmail.com
+ Yahoo!: VitalyBe
+
+Tuesday, May 25, 2004, 6:37:44 PM, you wrote:
+
+JvD> Vitaly Belman wrote:
+>> 
+>> If you'll be so kind though, I'd be glad if you could spot anything to
+>> speed up in this query. Here's the query and its plan that happens
+>> without any caching:
+>> 
+>> -------------------------------------------------------------------------------------------------------------
+>> QUERY
+>> -----
+>> SELECT     bv_books. * ,
+>>            vote_avg, 
+>>            vote_count 
+>> FROM       bv_bookgenres, 
+>>            bv_books 
+>> WHERE      bv_books.book_id = bv_bookgenres.book_id AND 
+>>            bv_bookgenres.genre_id = 5830
+>> ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0; 
+>>  
+>> QUERY PLAN
+>> ----------
+>> Limit  (cost=2337.41..2337.43 rows=10 width=76) (actual
+>> time=7875.000..7875.000 rows=10 loops=1)
+>>   ->  Sort  (cost=2337.41..2337.94 rows=214 width=76) (actual
+>> time=7875.000..7875.000 rows=10 loops=1)
+>>         Sort Key: bv_books.vote_avg
+>>         ->  Nested Loop  (cost=0.00..2329.13 rows=214 width=76)
+>> (actual time=16.000..7844.000 rows=1993 loops=1)
+>>               ->  Index Scan using i_bookgenres_genre_id on
+>> bv_bookgenres  (cost=0.00..1681.54 rows=214 width=4) (actual
+>> time=16.000..3585.000 rows=1993 loops=1)
+>>                     Index Cond: (genre_id = 5830)
+>>               ->  Index Scan using bv_books_pkey on bv_books 
+>> (cost=0.00..3.01 rows=1 width=76) (actual time=2.137..2.137 rows=1
+>> loops=1993)
+>>                     Index Cond: (bv_books.book_id = "outer".book_id)
+>> Total runtime: 7875.000 ms
+
+JvD> Presuming that vote_avg is a field in the table bv_bookgenres, 
+JvD> try a composite index on genre_id and vote_avg and then see if 
+JvD> you can use the limit clause to reduce the number of loop 
+JvD> iterations from 1993 to 10.
+
+JvD> CREATE INDEX test_idx ON bv_bookgenres (genre_id, vote_avg);
+
+
+JvD> The following query tries to force that execution lan and, 
+JvD> presuming there is a foreign key relation between 
+JvD> bv_books.book_id AND bv_bookgenres.book_id, I expect it will give
+JvD> the same results, but be carefull with NULL's:
+
+JvD> SELECT	bv_books. * ,
+JvD> 	vote_avg,
+JvD> 	vote_count
+JvD> FROM 	(
+JvD> 		SELECT	bg.*
+JvD> 		FROM 	bv_bookgenres bg
+JvD> 		WHERE	bg.genre_id = 5830
+JvD> 		ORDER BY
+JvD> 			bg.vote_avg DESC
+JvD> 		LIMIT	10
+JvD> 	) bv_bookgenres,
+JvD> 	bv_books
+JvD> WHERE	bv_books.book_id = bv_bookgenres.book_id
+JvD> ORDER BY
+JvD> 	vote_avg DESC
+JvD> LIMIT	10;
+
+JvD> Jochem
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 25 18:08:17 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id LP85F9YC; Tue, 25 May 2004 17:07:49 -0400
+Subject: Re: Interpreting vmstat
+From: Robert Treat 
+To: Doug Y 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: <6.0.1.1.2.20040518133210.01eb9ec0@mail.traderonline.com>
+References: <6.0.1.1.2.20040518133210.01eb9ec0@mail.traderonline.com>
+Content-Type: text/plain
+Content-Transfer-Encoding: 7bit
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+Date: 25 May 2004 17:07:51 -0400
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+X-Sequence-Number: 7039
+
+On Tue, 2004-05-18 at 14:12, Doug Y wrote:
+> Run a query I've been having trouble with and watch the output of vmstat 
+> (linux):
+> 
+> $ vmstat 1
+>     procs                      memory    swap          io     system 
+>   cpu
+>   r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us 
+> sy  id
+>   0  0  0    148   8732 193652 
+> 2786668   0   0     0     0  292   151   0   2  98
+>   2  0  2    148   7040 193652 
+> 2786668   0   0     0   208  459   697  45  10  45
+>   0  0  0    148   9028 193652 
+> 2786684   0   0    16   644  318   613  25   4  71
+>   1  0  0    148   5092 193676 
+> 2780196   0   0    12   184  441   491  37   5  58
+>   0  1  0    148   5212 193684 
+> 2772512   0   0   112  9740  682  1063  45  12  43
+>   1  0  0    148   5444 193684 
+> 2771584   0   0   120  4216  464  1303  44   3  52
+>   1  0  0    148  12232 193660 
+> 2771620   0   0   244   628  340   681  43  20  38
+>   1  0  0    148  12168 193664 
+> 2771832   0   0   196   552  332   956  42   2  56
+>   1  0  0    148  12080 193664 
+> 2772248   0   0   272   204  371   201  40   1  59
+>   1  1  0    148  12024 193664 
+> 2772624   0   0   368     0  259   127  42   3  55
+> 
+> Thats the first 10 lines or so... the query takes 60 seconds to run.
+> 
+> I'm confused on the bo & bi parts of the io:
+>     IO
+>         bi: Blocks sent to a block device (blocks/s).
+>         bo: Blocks received from a block device (blocks/s).
+> 
+> yet it seems to be opposite of that... bi only increases when doing a 
+> largish query, while bo also goes up, I typically see periodic bo numbers 
+> in the low 100's, which I'd guess are log writes.
+> 
+> I would think that my entire DB should end up cached since a raw pg_dump 
+> file is about 1G in size, yet my performance doesn't indicate that that is 
+> the case... running the same query a few minutes later, I'm not seeing a 
+> significant performance improvement.
+> 
+
+Been meaning to try and address this thread since it touches on one of
+the areas that I think is sorely lacking in the postgresql admin
+knowledge base; how to use various unix commands to deduce performance
+information. This would seem even more important given that PostgreSQL
+admins are expected to use said tools to find out some information that
+the commercial databases provide to there users... but alas this is
+-performance and not -advocacy so let me get on with it eh?
+
+As you noted, bi and bo are actually reversed, and I believe if you
+search the kernel hackers mailing lists you'll find references to
+this...  here's some more empirical evidence though, the following
+vmstat was taken from a high-write traffic monitoring type database
+application... 
+
+   procs                      memory    swap          io     system         cpu
+ r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
+ 1  0  0  27412 593336 112036 1865936   0   1     0     1    1     0   1   0   0
+ 5  1  1  27412 593336 112036 1865952   0   0     0   477  600  1346  53   7  40
+ 4  0  0  27412 593336 112036 1865960   0   0     0  1296  731  2087  47   5  48
+ 3  3  2  27412 594408 112052 1865972   4   0     4  2973  904  2957  32  20  48
+ 3  1  1  26596 594544 112068 1865976  64   0    64  1433  770  2766  41  22  37
+ 1  1  1  26596 594544 112072 1866004   0   0     5   959  702  1687  50  10  41
+ 3  1  1  26596 594512 112072 1866024   0   0     0  1155  731  2209  52  12  37
+ 2  0  0  26596 594512 112072 1866040   0   0     0   635  511  1293  48   5  46
+ 0  1  1  26596 594472 112076 1866076   0   0     7   739  551  1248  49   8  43
+ 1  0  0  26596 594472 112076 1866088   0   0     0  1048  598  1295  49   8  43
+ 2  0  0  26596 594208 112084 1866696   0   0   203  1253  686  1506  42  16  41
+ 1  0  0  26596 593920 112084 1866716   0   0     0  1184  599  1329  39  12  49
+ 0  1  1  26596 593060 112084 1866740   0   0     3  1036  613  3442  48   8  44
+ 0  1  2  26596 592920 112084 1866752   0   0     0  3825  836  1323   9  14  76
+ 0  0  0  26596 593544 112084 1866788   0   0     0  1064  625  1197   9  15  76
+ 0  1  1  26596 596300 112088 1866808   0   0     0   747  625  1558   7  13  79
+ 0  0  1  26596 599600 112100 1866892   0   0     0   468  489  1331   6   4  91
+ 0  0  0  26596 599600 112100 1866896   0   0     0   237  418   997   5   4  91
+ 0  1  1  26596 599600 112104 1866896   0   0     0  1063  582  1371   7   7  86
+ 0  0  0  26596 599612 112104 1866904   0   0     0   561  648  1556   6   4  89
+
+notice all the bo as it continually writes data to disk. Also notice how
+generally speaking it has no bi since it does not have to pull data up
+from disk... you will notice that the couple of times it grabs
+information from swap space, you'll also find a corresponding pull on
+the io.  
+
+getting back to your issue in order to determine if there is a problem
+in this case, you need to run explain analyze a few times repeatedly,
+take the relative score given by these runs, and then come back 5-10
+minutes later and run explain analyze again and see if the results are
+drastically different. troll vmstat while you do this to see if there is
+bi occurring.  I probably should mention that just because you see
+activity on bi doesn't mean that you'll notice any difference in
+performance against running the query with no bi, it's dependent on a
+number of factors really.  
+
+Oh, and as the other poster alluded to, knock down your shared buffers
+by about 50% and see where that gets you. I might also knock *up* your
+effective cache size... try doubling that and see how things go. 
+
+Hope this helps... and others jump in with corrections if needed.
+
+Robert Treat
+-- 
+Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
+
+
+From pgsql-performance-owner@postgresql.org  Tue May 25 19:32:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-ID: <40B3C792.3020106@outputservices.com>
+Date: Tue, 25 May 2004 16:24:18 -0600
+From: Marty Scholes 
+User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:0.9.9) Gecko/20020517
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Vitaly Belman 
+Cc: Jochem van Dieten ,
+	pgsql-performance@postgresql.org, Marty Scholes 
+Subject: Re: PostgreSQL caching
+References: <20792805375.20040521203337@012.net.il>
+	<40B36848.1090403@oli.tudelft.nl>
+	<1371146711781.20040525225305@012.net.il>
+Content-Type: text/plain; charset=ISO-8859-15; format=flowed
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+
+Vitaly,
+
+This looks like there might be some room for performance improvement...
+
+ > MS> I didn't see the table structure, but I assume
+ > MS> that the vote_avg and
+ > MS> vote_count fields are in bv_bookgenres.
+ >
+ > I didn't understand you. vote_avg is stored in bv_books.
+
+Ok.  That helps.  The confusion (on my end) came from the SELECT clause 
+of the query you provided:
+
+ > SELECT     bv_books. * ,
+ >            vote_avg,
+ >            vote_count
+
+All fields from bv_books were selected (bv_books.*) along with vote_agv 
+and vote_count.  My assumption was that vote_avg and vote_count were 
+therefore not in bv_books.
+
+At any rate, a query with an IN clause should help quite a bit:
+
+SELECT     bv_books. *
+FROM       bv_books
+WHERE      bv_books.book_id IN (
+               SELECT book_id
+               FROM bv_genres
+               WHERE bv_bookgenres.genre_id = 5830
+               )
+ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0;
+
+Give it a whirl.
+
+Marty
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 10:14:54 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	id LP85GDKP; Wed, 26 May 2004 09:13:58 -0400
+Subject: Re: PostgreSQL caching
+From: Robert Treat 
+To: Vitaly Belman 
+Cc: Jochem van Dieten ,
+	Marty Scholes , pgsql-performance@postgresql.org
+In-Reply-To: <1371146711781.20040525225305@012.net.il>
+References: <20792805375.20040521203337@012.net.il>
+	<40B36848.1090403@oli.tudelft.nl>
+	<1371146711781.20040525225305@012.net.il>
+Content-Type: text/plain
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+Date: 26 May 2004 09:13:58 -0400
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+
+On Tue, 2004-05-25 at 15:53, Vitaly Belman wrote:
+> >>  
+> >> QUERY PLAN
+> >> ----------
+> >> Limit  (cost=2337.41..2337.43 rows=10 width=76) (actual
+> >> time=7875.000..7875.000 rows=10 loops=1)
+> >>   ->  Sort  (cost=2337.41..2337.94 rows=214 width=76) (actual
+> >> time=7875.000..7875.000 rows=10 loops=1)
+> >>         Sort Key: bv_books.vote_avg
+> >>         ->  Nested Loop  (cost=0.00..2329.13 rows=214 width=76)
+> >> (actual time=16.000..7844.000 rows=1993 loops=1)
+> >>               ->  Index Scan using i_bookgenres_genre_id on
+> >> bv_bookgenres  (cost=0.00..1681.54 rows=214 width=4) (actual
+> >> time=16.000..3585.000 rows=1993 loops=1)
+> >>                     Index Cond: (genre_id = 5830)
+> >>               ->  Index Scan using bv_books_pkey on bv_books 
+> >> (cost=0.00..3.01 rows=1 width=76) (actual time=2.137..2.137 rows=1
+> >> loops=1993)
+> >>                     Index Cond: (bv_books.book_id = "outer".book_id)
+> >> Total runtime: 7875.000 ms
+> 
+
+A question and two experiments... what version of postgresql is this?
+
+Try reindexing i_bookgenres_genre_id and capture the explain analyze for
+that. If it doesn't help try doing set enable_indexscan = false and
+capture the explain analyze for that. 
+
+Robert Treat
+-- 
+Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 10:29:29 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	id LP85GD3D; Wed, 26 May 2004 09:29:06 -0400
+Subject: Re: where to find out when a table was last analyzed?
+From: Robert Treat 
+To: Litao Wu 
+Cc: pgsql-performance@postgresql.org
+In-Reply-To: <20040518211321.23032.qmail@web13121.mail.yahoo.com>
+References: <20040518211321.23032.qmail@web13121.mail.yahoo.com>
+Content-Type: text/plain
+Content-Transfer-Encoding: 7bit
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+Date: 26 May 2004 09:29:06 -0400
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+
+On Tue, 2004-05-18 at 17:13, Litao Wu wrote:
+> All,
+> 
+> Does PG store when a table was last analyzed?
+> 
+> Thanks,
+> 
+
+no. you can do something like select attname,s.* from pg_statistic s,
+pg_attribute a, pg_class c where starelid = c.oid and attrelid = c.oid
+and staattnum = attnum and relname = 'mytable' to see the current
+statistics on the table, but its not timestamped. 
+
+Robert Treat
+-- 
+Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 11:33:21 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Wed, 26 May 2004 17:33:56 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <1673440625.20040526173356@012.net.il>
+To: Marty Scholes ,
+	Robert Treat ,
+	Nick Barr 
+Cc: Jochem van Dieten ,
+	pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+In-Reply-To: <40B3C792.3020106@outputservices.com>
+References: <20792805375.20040521203337@012.net.il>
+	<40B36848.1090403@oli.tudelft.nl>
+	<1371146711781.20040525225305@012.net.il>
+	<40B3C792.3020106@outputservices.com>
+MIME-Version: 1.0
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+
+Hello Marty, Nick and Robert,
+
+NB> Depending on what version of PG you are running, IN might take a while
+NB> to complete. If so try an EXISTS instead
+
+RT> A question and two experiments... what version of postgresql is this?
+
+I am using the newer 7.5dev native Windows port. For this reason I
+don't think that IN will cause any trouble (I read that this issue was
+resolved in 7.4).
+
+MS> At any rate, a query with an IN clause should help quite a bit
+
+MS> SELECT     bv_books. *
+MS> FROM       bv_books
+MS> WHERE      bv_books.book_id IN (
+MS>                SELECT book_id
+MS>                FROM bv_genres
+MS>                WHERE bv_bookgenres.genre_id = 5830
+MS>                )
+MS> ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0;
+
+It looks like it helps a bit (though you meant "FROM bv_bookgenres",
+right?). I can't tell you how MUCH it helped though, because of two
+reasons:
+
+1) As soon as I run a query, it is cached in the memory and I can't
+really find a good way to flush it out of there to test again except a
+full computer reset (shutting postmaster down doesn't help). If you
+have a better idea on this, do tell me =\ (Reminding again, I am on
+Windows).
+
+2) I *think* I resolved this issue, at least for most of the genre_ids
+(didn't go through them all, but tried a few with different book count
+and the results looked quite good). The fault was partly mine, a few
+weeks ago I increase the statistics for the genre_id column a bit too
+much (from 10 to 70), I was unsure how exactly it works (and still am)
+but it helped for a few genre_ids that had a high book count, yet it
+also hurt the performence for the genres without as much ids. I now
+halved the stastics (to 58) and almost everything looks good now.
+
+Because of that I'll stop working on that query for a while (unless
+you have some more performance tips on the subject). Big thanks to
+everyone who helped.. And I might bring this issue later again, it it
+still will cause too much troubles.
+
+RT> Try reindexing i_bookgenres_genre_id and capture the explain
+RT> analyze for that.
+
+Is that's what you meant "REINDEX INDEX i_bookgenres_genre_id"? But it
+returns no messages what-so-ever =\. I can EXPLAIN it either.
+
+RT> If it doesn't help try doing set enable_indexscan = false and
+RT> capture the explain analyze for that.
+
+Here it is:
+
+------------------------------------------------------------------------------------------------------------------------------------------
+QUERY PLAN
+Limit  (cost=41099.93..41099.96 rows=10 width=76) (actual time=6734.000..6734.000 rows=10 loops=1)
+  ->  Sort  (cost=41099.93..41100.45 rows=208 width=76) (actual time=6734.000..6734.000 rows=10 loops=1)
+        Sort Key: bv_books.vote_count
+        ->  Merge Join  (cost=40229.21..41091.92 rows=208 width=76) (actual time=6078.000..6593.000 rows=1993 loops=1)
+              Merge Cond: ("outer".book_id = "inner".book_id)
+              ->  Sort  (cost=16817.97..16818.49 rows=208 width=4) (actual time=1062.000..1062.000 rows=1993 loops=1)
+                    Sort Key: bv_bookgenres.book_id
+                    ->  Seq Scan on bv_bookgenres  (cost=0.00..16809.96 rows=208 width=4) (actual time=0.000..1047.000 rows=1993 loops=1)
+                          Filter: (genre_id = 5830)
+              ->  Sort  (cost=23411.24..23841.04 rows=171918 width=76) (actual time=5016.000..5189.000 rows=171801 loops=1)
+                    Sort Key: bv_books.book_id
+                    ->  Seq Scan on bv_books  (cost=0.00..4048.18 rows=171918 width=76) (actual time=0.000..359.000 rows=171918 loops=1)
+Total runtime: 6734.000 ms
+------------------------------------------------------------------------------------------------------------------------------------------
+
+Regards,
+ Vitaly Belman
+ 
+ ICQ: 1912453
+ AIM: VitalyB1984
+ MSN: tmdagent@hotmail.com
+ Yahoo!: VitalyBe
+
+Wednesday, May 26, 2004, 1:24:18 AM, you wrote:
+
+MS> Vitaly,
+
+MS> This looks like there might be some room for performance improvement...
+
+ >> MS> I didn't see the table structure, but I assume
+ >> MS> that the vote_avg and
+ >> MS> vote_count fields are in bv_bookgenres.
+ >>
+ >> I didn't understand you. vote_avg is stored in bv_books.
+
+MS> Ok.  That helps.  The confusion (on my end) came from the SELECT clause
+MS> of the query you provided:
+
+ >> SELECT     bv_books. * ,
+ >>            vote_avg,
+ >>            vote_count
+
+MS> All fields from bv_books were selected (bv_books.*) along with vote_agv
+MS> and vote_count.  My assumption was that vote_avg and vote_count were
+MS> therefore not in bv_books.
+
+MS> At any rate, a query with an IN clause should help quite a bit:
+
+MS> SELECT     bv_books. *
+MS> FROM       bv_books
+MS> WHERE      bv_books.book_id IN (
+MS>                SELECT book_id
+MS>                FROM bv_genres
+MS>                WHERE bv_bookgenres.genre_id = 5830
+MS>                )
+MS> ORDER BY   vote_avg DESC LIMIT 10 OFFSET 0;
+
+MS> Give it a whirl.
+
+MS> Marty
+
+
+MS> ---------------------------(end of
+MS> broadcast)---------------------------
+MS> TIP 6: Have you searched our list archives?
+
+MS>                http://archives.postgresql.org
+
+
+From pgsql-general-owner@postgresql.org  Wed May 26 12:34:55 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	Wed, 26 May 2004 11:26:30 -0400 (VET)
+Message-ID: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+Date: Wed, 26 May 2004 11:26:30 -0400 (VET)
+Subject: performance very slow
+From: "Mario Soto" 
+To: 
+X-Priority: 1
+Importance: High
+X-Mailer: SquirrelMail (version 1.2.10)
+MIME-Version: 1.0
+Content-Type: text/plain; charset=iso-8859-1
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+X-Spam-Level: 
+X-Archive-Number: 200405/791
+X-Sequence-Number: 61225
+
+Hi. i hava a postresql 7.4.2 in a production server.
+
+tha machine is a Pentium IV 2,6 GHZ AND 1 GB IN RAM with lINUX RH 9.0.
+
+The postresql.conf say:
+
+#---------------------------------------------------------------------------
+# RESOURCE USAGE (except WAL)
+#---------------------------------------------------------------------------
+
+# - Memory -
+
+shared_buffers = 1000           # min 16, at least max_connections*2, 8KB
+each
+sort_mem = 1024         # min 64, size in KB
+vacuum_mem = 8192               # min 1024, size in KB
+
+# - Free Space Map -
+
+max_fsm_pages = 20000           # min max_fsm_relations*16, 6 bytes each
+max_fsm_relations = 1000        # min 100, ~50 bytes each
+
+# - Kernel Resource Usage -
+
+max_files_per_process = 1000    # min 25
+#preload_libraries = ''
+
+
+#---------------------------------------------------------------------------
+# WRITE AHEAD LOG
+#---------------------------------------------------------------------------
+
+# - Settings -
+
+fsync = true                    # turns forced synchronization on or off
+wal_sync_method = fsync # the default varies across platforms:
+                                # fsync, fdatasync, open_sync, or
+open_datasync
+wal_buffers = 8         # min 4, 8KB each
+
+# - Checkpoints -
+
+checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
+checkpoint_timeout = 300        # range 30-3600, in seconds
+checkpoint_warning = 30 # 0 is off, in seconds
+commit_delay = 0                # range 0-100000, in microseconds
+commit_siblings = 5             # range 1-1000
+
+#---------------------------------------------------------------------------
+# QUERY TUNING
+#---------------------------------------------------------------------------
+
+# - Planner Method Enabling -
+
+enable_hashagg = true
+enable_hashjoin = true
+enable_indexscan = true
+enable_mergejoin = true
+enable_nestloop = true
+enable_seqscan = true
+enable_sort = true
+enable_tidscan = true
+
+# - Planner Cost Constants -
+
+effective_cache_size = 1000     # typically 8KB each
+random_page_cost = 4            # units are one sequential page fetch cost
+cpu_tuple_cost = 0.01           # (same)
+cpu_index_tuple_cost = 0.001    # (same)
+cpu_operator_cost = 0.0025      # (same)
+
+# - Genetic Query Optimizer -
+
+geqo = true
+geqo_threshold = 11
+geqo_effort = 1
+geqo_generations = 0
+geqo_pool_size = 0              # default based on tables in statement,
+                                # range 128-1024
+geqo_selection_bias = 2.0       # range 1.5-2.0
+
+# - Other Planner Options -
+
+default_statistics_target = 100 # range 1-1000
+from_collapse_limit = 30
+join_collapse_limit = 30        # 1 disables collapsing of explicit JOINs
+
+
+#---------------------------------------------------------------------------
+# ERROR REPORTING AND LOGGING
+#---------------------------------------------------------------------------
+
+# - Syslog -
+
+#syslog = 0                     # range 0-2; 0=stdout; 1=both; 2=syslog
+#syslog_facility = 'LOCAL0'
+#syslog_ident = 'postgres'
+
+# - When to Log -
+
+#client_min_messages = notice   # Values, in order of decreasing detail:
+                                #   debug5, debug4, debug3, debug2, debug1,
+                                #   log, info, notice, warning, error
+
+#log_min_messages = notice      # Values, in order of decreasing detail:
+                                #   debug5, debug4, debug3, debug2, debug1,
+                                #   info, notice, warning, error, log, fatal,
+                                #   panic
+
+#log_error_verbosity = default   # terse, default, or verbose messages
+
+#log_min_error_statement = panic # Values in order of increasing severity:
+                                 #   debug5, debug4, debug3, debug2, debug1,
+                                 #   info, notice, warning, error, panic(off)
+
+#log_min_duration_statement = -1 # Log all statements whose
+                                 # execution time exceeds the value, in
+                                 # milliseconds.  Zero prints all queries.
+                                 # Minus-one disables.
+
+#silent_mode = false             # DO NOT USE without Syslog!
+
+# - What to Log -
+
+
+
+debug_print_parse = true
+debug_print_rewritten = true
+debug_print_plan = true
+debug_pretty_print = true
+log_connections = true
+log_duration = true
+log_pid = true
+log_statement = true
+log_timestamp = true
+log_hostname = true
+log_source_port = true
+
+
+#---------------------------------------------------------------------------
+# RUNTIME STATISTICS
+#---------------------------------------------------------------------------
+
+# - Statistics Monitoring -
+
+log_parser_stats = true
+log_planner_stats = true
+log_executor_stats = true
+#log_statement_stats = true
+
+# - Query/Index Statistics Collector -
+
+stats_start_collector = true
+stats_command_string = true
+stats_block_level = true
+stats_row_level = true
+stats_reset_on_server_start = true
+
+
+#---------------------------------------------------------------------------
+# CLIENT CONNECTION DEFAULTS
+#---------------------------------------------------------------------------
+
+# - Statement Behavior -
+
+#search_path = '$user,public'   # schema names
+#check_function_bodies = true
+#default_transaction_isolation = 'read committed'
+#default_transaction_read_only = false
+#statement_timeout = 0          # 0 is disabled, in milliseconds
+
+# - Locale and Formatting -
+
+#datestyle = 'iso, mdy'
+#timezone = unknown             # actually, defaults to TZ environment
+setting
+#australian_timezones = false
+#extra_float_digits = 0         # min -15, max 2
+#client_encoding = sql_ascii    # actually, defaults to database encoding
+
+# These settings are initialized by initdb -- they may be changed
+lc_messages = 'es_VE.UTF-8'             # locale for system error message
+strings
+lc_monetary = 'es_VE.UTF-8'             # locale for monetary formatting
+lc_numeric = 'es_VE.UTF-8'              # locale for number formatting
+lc_time = 'es_VE.UTF-8'                 # locale for time formatting
+
+# - Other Defaults -
+
+explain_pretty_print = true
+#dynamic_library_path = '$libdir'
+#max_expr_depth = 10000         # min 10
+
+
+#---------------------------------------------------------------------------
+# LOCK MANAGEMENT
+#---------------------------------------------------------------------------
+
+#deadlock_timeout = 1000        # in milliseconds
+#max_locks_per_transaction = 64 # min 10, ~260*max_connections bytes each
+
+
+#---------------------------------------------------------------------------
+# VERSION/PLATFORM COMPATIBILITY
+#---------------------------------------------------------------------------
+
+# - Previous Postgres Versions -
+
+#add_missing_from = true
+#regex_flavor = advanced        # advanced, extended, or basic
+#sql_inheritance = true
+
+# - Other Platforms & Clients -
+
+#transform_null_equals = false
+
+
+
+BUT THE PERFORMANCE IT�S VERY SLOW
+
+what can do ?????
+
+Thank
+
+
+Mario Soto
+
+
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 13:18:44 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
+	by svr1.postgresql.org (Postfix) with ESMTP id 74A74D1B1B2
+	for ;
+	Wed, 26 May 2004 13:18:41 -0300 (ADT)
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+	[209.128.84.228])
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+	for ;
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+	with ESMTP id 5203961; Wed, 26 May 2004 09:19:53 -0700
+Content-Type: text/plain;
+  charset="iso-8859-1"
+From: Josh Berkus 
+Organization: Aglio Database Solutions
+To: Vitaly Belman 
+Subject: Re: PostgreSQL caching
+Date: Wed, 26 May 2004 09:17:35 -0700
+User-Agent: KMail/1.4.3
+Cc: pgsql-performance@postgresql.org
+References: <20792805375.20040521203337@012.net.il>
+	<40B3C792.3020106@outputservices.com>
+	<1673440625.20040526173356@012.net.il>
+In-Reply-To: <1673440625.20040526173356@012.net.il>
+MIME-Version: 1.0
+Content-Transfer-Encoding: 8bit
+Message-Id: <200405260917.35537.josh@agliodbs.com>
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+X-Spam-Level: 
+X-Archive-Number: 200405/213
+X-Sequence-Number: 7044
+
+Vitaly,
+
+> I am using the newer 7.5dev native Windows port. For this reason I
+> don't think that IN will cause any trouble (I read that this issue was
+> resolved in 7.4).
+
+Well, for performance, all bets are off for the dev Windows port.   Last I 
+checked, the Win32 team was still working on *stability* and hadn't yet even 
+looked at performance.  Not that you can't improve the query, just that it 
+might not fix the problem.
+
+Therefore ... your detailed feedback is appreciated, especially if you can 
+compare stuff to the same database running on a Linux, Unix, or BSD machine.
+
+-- 
+Josh Berkus
+Aglio Database Solutions
+San Francisco
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 13:26:19 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
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+	with ESMTP id 45285-06
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+	Wed, 26 May 2004 13:25:52 -0300 (ADT)
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+	Wed, 26 May 2004 12:25:43 -0400
+Message-ID: <40B4C509.4000902@lulu.com>
+Date: Wed, 26 May 2004 12:25:45 -0400
+From: Bill Montgomery 
+User-Agent: Mozilla Thunderbird 0.5 (X11/20040210)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Mario Soto ,
+	pgsql-performance@postgresql.org
+Subject: Re: [GENERAL] performance very slow
+References: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+In-Reply-To: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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+X-Spam-Level: 
+X-Archive-Number: 200405/214
+X-Sequence-Number: 7045
+
+Mario Soto wrote:
+
+>Hi. i hava a postresql 7.4.2 in a production server.
+>
+>tha machine is a Pentium IV 2,6 GHZ AND 1 GB IN RAM with lINUX RH 9.0.
+>  
+>
+Mario,
+
+Start with reading this:
+
+http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+
+Without knowing anything about the size of your database, your usage 
+patterns, or your disk subsystem (the most important part of a database 
+server, imho) I would suggest you first increase the number of 
+shared_buffers allocated to Postgres. Most recommend keeping this number 
+below 10000, but I've found I get the best performance with about 24000 
+shared_buffers with a ~5GB database on a machine with 4GB of ram, 
+dedicated to Postgres. You'll have to experiment to see what works best 
+for you.
+
+Also, make sure you VACUUM and ANALYZE on a regular basis. Again, the 
+frequency of this really depends on your data and usage patterns. More 
+frequent write operations require more frequent vacuuming.
+
+Good luck.
+
+Best Regards,
+
+Bill Montgomery
+
+>The postresql.conf say:
+>
+>#---------------------------------------------------------------------------
+># RESOURCE USAGE (except WAL)
+>#---------------------------------------------------------------------------
+>
+># - Memory -
+>
+>shared_buffers = 1000           # min 16, at least max_connections*2, 8KB
+>each
+>sort_mem = 1024         # min 64, size in KB
+>vacuum_mem = 8192               # min 1024, size in KB
+>
+># - Free Space Map -
+>
+>max_fsm_pages = 20000           # min max_fsm_relations*16, 6 bytes each
+>max_fsm_relations = 1000        # min 100, ~50 bytes each
+>
+># - Kernel Resource Usage -
+>
+>max_files_per_process = 1000    # min 25
+>#preload_libraries = ''
+>
+>
+>#---------------------------------------------------------------------------
+># WRITE AHEAD LOG
+>#---------------------------------------------------------------------------
+>
+># - Settings -
+>
+>fsync = true                    # turns forced synchronization on or off
+>wal_sync_method = fsync # the default varies across platforms:
+>                                # fsync, fdatasync, open_sync, or
+>open_datasync
+>wal_buffers = 8         # min 4, 8KB each
+>
+># - Checkpoints -
+>
+>checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
+>checkpoint_timeout = 300        # range 30-3600, in seconds
+>checkpoint_warning = 30 # 0 is off, in seconds
+>commit_delay = 0                # range 0-100000, in microseconds
+>commit_siblings = 5             # range 1-1000
+>
+>#---------------------------------------------------------------------------
+># QUERY TUNING
+>#---------------------------------------------------------------------------
+>
+># - Planner Method Enabling -
+>
+>enable_hashagg = true
+>enable_hashjoin = true
+>enable_indexscan = true
+>enable_mergejoin = true
+>enable_nestloop = true
+>enable_seqscan = true
+>enable_sort = true
+>enable_tidscan = true
+>
+># - Planner Cost Constants -
+>
+>effective_cache_size = 1000     # typically 8KB each
+>random_page_cost = 4            # units are one sequential page fetch cost
+>cpu_tuple_cost = 0.01           # (same)
+>cpu_index_tuple_cost = 0.001    # (same)
+>cpu_operator_cost = 0.0025      # (same)
+>
+># - Genetic Query Optimizer -
+>
+>geqo = true
+>geqo_threshold = 11
+>geqo_effort = 1
+>geqo_generations = 0
+>geqo_pool_size = 0              # default based on tables in statement,
+>                                # range 128-1024
+>geqo_selection_bias = 2.0       # range 1.5-2.0
+>
+># - Other Planner Options -
+>
+>default_statistics_target = 100 # range 1-1000
+>from_collapse_limit = 30
+>join_collapse_limit = 30        # 1 disables collapsing of explicit JOINs
+>
+>
+>#---------------------------------------------------------------------------
+># ERROR REPORTING AND LOGGING
+>#---------------------------------------------------------------------------
+>
+># - Syslog -
+>
+>#syslog = 0                     # range 0-2; 0=stdout; 1=both; 2=syslog
+>#syslog_facility = 'LOCAL0'
+>#syslog_ident = 'postgres'
+>
+># - When to Log -
+>
+>#client_min_messages = notice   # Values, in order of decreasing detail:
+>                                #   debug5, debug4, debug3, debug2, debug1,
+>                                #   log, info, notice, warning, error
+>
+>#log_min_messages = notice      # Values, in order of decreasing detail:
+>                                #   debug5, debug4, debug3, debug2, debug1,
+>                                #   info, notice, warning, error, log, fatal,
+>                                #   panic
+>
+>#log_error_verbosity = default   # terse, default, or verbose messages
+>
+>#log_min_error_statement = panic # Values in order of increasing severity:
+>                                 #   debug5, debug4, debug3, debug2, debug1,
+>                                 #   info, notice, warning, error, panic(off)
+>
+>#log_min_duration_statement = -1 # Log all statements whose
+>                                 # execution time exceeds the value, in
+>                                 # milliseconds.  Zero prints all queries.
+>                                 # Minus-one disables.
+>
+>#silent_mode = false             # DO NOT USE without Syslog!
+>
+># - What to Log -
+>
+>
+>
+>debug_print_parse = true
+>debug_print_rewritten = true
+>debug_print_plan = true
+>debug_pretty_print = true
+>log_connections = true
+>log_duration = true
+>log_pid = true
+>log_statement = true
+>log_timestamp = true
+>log_hostname = true
+>log_source_port = true
+>
+>
+>#---------------------------------------------------------------------------
+># RUNTIME STATISTICS
+>#---------------------------------------------------------------------------
+>
+># - Statistics Monitoring -
+>
+>log_parser_stats = true
+>log_planner_stats = true
+>log_executor_stats = true
+>#log_statement_stats = true
+>
+># - Query/Index Statistics Collector -
+>
+>stats_start_collector = true
+>stats_command_string = true
+>stats_block_level = true
+>stats_row_level = true
+>stats_reset_on_server_start = true
+>
+>
+>#---------------------------------------------------------------------------
+># CLIENT CONNECTION DEFAULTS
+>#---------------------------------------------------------------------------
+>
+># - Statement Behavior -
+>
+>#search_path = '$user,public'   # schema names
+>#check_function_bodies = true
+>#default_transaction_isolation = 'read committed'
+>#default_transaction_read_only = false
+>#statement_timeout = 0          # 0 is disabled, in milliseconds
+>
+># - Locale and Formatting -
+>
+>#datestyle = 'iso, mdy'
+>#timezone = unknown             # actually, defaults to TZ environment
+>setting
+>#australian_timezones = false
+>#extra_float_digits = 0         # min -15, max 2
+>#client_encoding = sql_ascii    # actually, defaults to database encoding
+>
+># These settings are initialized by initdb -- they may be changed
+>lc_messages = 'es_VE.UTF-8'             # locale for system error message
+>strings
+>lc_monetary = 'es_VE.UTF-8'             # locale for monetary formatting
+>lc_numeric = 'es_VE.UTF-8'              # locale for number formatting
+>lc_time = 'es_VE.UTF-8'                 # locale for time formatting
+>
+># - Other Defaults -
+>
+>explain_pretty_print = true
+>#dynamic_library_path = '$libdir'
+>#max_expr_depth = 10000         # min 10
+>
+>
+>#---------------------------------------------------------------------------
+># LOCK MANAGEMENT
+>#---------------------------------------------------------------------------
+>
+>#deadlock_timeout = 1000        # in milliseconds
+>#max_locks_per_transaction = 64 # min 10, ~260*max_connections bytes each
+>
+>
+>#---------------------------------------------------------------------------
+># VERSION/PLATFORM COMPATIBILITY
+>#---------------------------------------------------------------------------
+>
+># - Previous Postgres Versions -
+>
+>#add_missing_from = true
+>#regex_flavor = advanced        # advanced, extended, or basic
+>#sql_inheritance = true
+>
+># - Other Platforms & Clients -
+>
+>#transform_null_equals = false
+>
+>
+>
+>BUT THE PERFORMANCE IT�S VERY SLOW
+>
+>what can do ?????
+>
+>Thank
+>
+>
+>Mario Soto
+>
+>
+>
+>---------------------------(end of broadcast)---------------------------
+>TIP 2: you can get off all lists at once with the unregister command
+>    (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
+>  
+>
+
+
+From pgsql-performance-owner@postgresql.org  Fri May 28 20:56:44 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+	for ;
+	Wed, 26 May 2004 13:39:30 -0300 (ADT)
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+ <38009.200.35.66.77.1085589357.squirrel@mail.venezolanadeavaluos.com>
+Date: Wed, 26 May 2004 12:35:57 -0400 (VET)
+Subject: Re: [GENERAL] performance very slow
+From: "Mario Soto" 
+To: 
+In-Reply-To: <40B4C509.4000902@lulu.com>
+References: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+	<40B4C509.4000902@lulu.com>
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+Cc: 
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+
+OK. Thank fou your help.
+
+In this moment the size of database its 2GB.
+
+And the machine it�s only to postgresql.
+
+Gracias
+
+
+> Mario Soto wrote:
+>
+>>Hi. i hava a postresql 7.4.2 in a production server.
+>>
+>>tha machine is a Pentium IV 2,6 GHZ AND 1 GB IN RAM with lINUX RH 9.0.
+>>
+>>
+> Mario,
+>
+> Start with reading this:
+>
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+>
+> Without knowing anything about the size of your database, your usage
+> patterns, or your disk subsystem (the most important part of a database
+> server, imho) I would suggest you first increase the number of
+> shared_buffers allocated to Postgres. Most recommend keeping this number
+>  below 10000, but I've found I get the best performance with about 24000
+>  shared_buffers with a ~5GB database on a machine with 4GB of ram,
+> dedicated to Postgres. You'll have to experiment to see what works best
+> for you.
+>
+> Also, make sure you VACUUM and ANALYZE on a regular basis. Again, the
+> frequency of this really depends on your data and usage patterns. More
+> frequent write operations require more frequent vacuuming.
+>
+> Good luck.
+>
+> Best Regards,
+>
+> Bill Montgomery
+>
+>>The postresql.conf say:
+>>
+>>#---------------------------------------------------------------------------
+>> # RESOURCE USAGE (except WAL)
+>>#---------------------------------------------------------------------------
+>>
+>># - Memory -
+>>
+>>shared_buffers = 1000           # min 16, at least max_connections*2,
+>> 8KB each
+>>sort_mem = 1024         # min 64, size in KB
+>>vacuum_mem = 8192               # min 1024, size in KB
+>>
+>># - Free Space Map -
+>>
+>>max_fsm_pages = 20000           # min max_fsm_relations*16, 6 bytes
+>> each max_fsm_relations = 1000        # min 100, ~50 bytes each
+>>
+>># - Kernel Resource Usage -
+>>
+>>max_files_per_process = 1000    # min 25
+>>#preload_libraries = ''
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # WRITE AHEAD LOG
+>>#---------------------------------------------------------------------------
+>>
+>># - Settings -
+>>
+>>fsync = true                    # turns forced synchronization on or
+>> off wal_sync_method = fsync # the default varies across platforms:
+>>                                # fsync, fdatasync, open_sync, or
+>>open_datasync
+>>wal_buffers = 8         # min 4, 8KB each
+>>
+>># - Checkpoints -
+>>
+>>checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
+>>checkpoint_timeout = 300        # range 30-3600, in seconds
+>>checkpoint_warning = 30 # 0 is off, in seconds
+>>commit_delay = 0                # range 0-100000, in microseconds
+>> commit_siblings = 5             # range 1-1000
+>>
+>>#---------------------------------------------------------------------------
+>> # QUERY TUNING
+>>#---------------------------------------------------------------------------
+>>
+>># - Planner Method Enabling -
+>>
+>>enable_hashagg = true
+>>enable_hashjoin = true
+>>enable_indexscan = true
+>>enable_mergejoin = true
+>>enable_nestloop = true
+>>enable_seqscan = true
+>>enable_sort = true
+>>enable_tidscan = true
+>>
+>># - Planner Cost Constants -
+>>
+>>effective_cache_size = 1000     # typically 8KB each
+>>random_page_cost = 4            # units are one sequential page fetch
+>> cost cpu_tuple_cost = 0.01           # (same)
+>>cpu_index_tuple_cost = 0.001    # (same)
+>>cpu_operator_cost = 0.0025      # (same)
+>>
+>># - Genetic Query Optimizer -
+>>
+>>geqo = true
+>>geqo_threshold = 11
+>>geqo_effort = 1
+>>geqo_generations = 0
+>>geqo_pool_size = 0              # default based on tables in statement,
+>>                                # range 128-1024
+>>geqo_selection_bias = 2.0       # range 1.5-2.0
+>>
+>># - Other Planner Options -
+>>
+>>default_statistics_target = 100 # range 1-1000
+>>from_collapse_limit = 30
+>>join_collapse_limit = 30        # 1 disables collapsing of explicit
+>> JOINs
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # ERROR REPORTING AND LOGGING
+>>#---------------------------------------------------------------------------
+>>
+>># - Syslog -
+>>
+>>#syslog = 0                     # range 0-2; 0=stdout; 1=both; 2=syslog
+>> #syslog_facility = 'LOCAL0'
+>>#syslog_ident = 'postgres'
+>>
+>># - When to Log -
+>>
+>>#client_min_messages = notice   # Values, in order of decreasing
+>> detail:
+>>                                #   debug5, debug4, debug3, debug2,
+>> debug1, #   log, info, notice, warning,
+>> error
+>>
+>>#log_min_messages = notice      # Values, in order of decreasing
+>> detail:
+>>                                #   debug5, debug4, debug3, debug2,
+>> debug1, #   info, notice, warning,
+>> error, log, fatal, #   panic
+>>
+>>#log_error_verbosity = default   # terse, default, or verbose messages
+>>
+>>#log_min_error_statement = panic # Values in order of increasing
+>> severity:
+>>                                 #   debug5, debug4, debug3, debug2,
+>> debug1, #   info, notice, warning,
+>> error, panic(off)
+>>
+>>#log_min_duration_statement = -1 # Log all statements whose
+>>                                 # execution time exceeds the value, in
+>> # milliseconds.  Zero prints all
+>> queries. # Minus-one disables.
+>>
+>>#silent_mode = false             # DO NOT USE without Syslog!
+>>
+>># - What to Log -
+>>
+>>
+>>
+>>debug_print_parse = true
+>>debug_print_rewritten = true
+>>debug_print_plan = true
+>>debug_pretty_print = true
+>>log_connections = true
+>>log_duration = true
+>>log_pid = true
+>>log_statement = true
+>>log_timestamp = true
+>>log_hostname = true
+>>log_source_port = true
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # RUNTIME STATISTICS
+>>#---------------------------------------------------------------------------
+>>
+>># - Statistics Monitoring -
+>>
+>>log_parser_stats = true
+>>log_planner_stats = true
+>>log_executor_stats = true
+>>#log_statement_stats = true
+>>
+>># - Query/Index Statistics Collector -
+>>
+>>stats_start_collector = true
+>>stats_command_string = true
+>>stats_block_level = true
+>>stats_row_level = true
+>>stats_reset_on_server_start = true
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # CLIENT CONNECTION DEFAULTS
+>>#---------------------------------------------------------------------------
+>>
+>># - Statement Behavior -
+>>
+>>#search_path = '$user,public'   # schema names
+>>#check_function_bodies = true
+>>#default_transaction_isolation = 'read committed'
+>>#default_transaction_read_only = false
+>>#statement_timeout = 0          # 0 is disabled, in milliseconds
+>>
+>># - Locale and Formatting -
+>>
+>>#datestyle = 'iso, mdy'
+>>#timezone = unknown             # actually, defaults to TZ environment
+>> setting
+>>#australian_timezones = false
+>>#extra_float_digits = 0         # min -15, max 2
+>>#client_encoding = sql_ascii    # actually, defaults to database
+>> encoding
+>>
+>># These settings are initialized by initdb -- they may be changed
+>> lc_messages = 'es_VE.UTF-8'             # locale for system error
+>> message strings
+>>lc_monetary = 'es_VE.UTF-8'             # locale for monetary
+>> formatting lc_numeric = 'es_VE.UTF-8'              # locale for number
+>> formatting lc_time = 'es_VE.UTF-8'                 # locale for time
+>> formatting
+>>
+>># - Other Defaults -
+>>
+>>explain_pretty_print = true
+>>#dynamic_library_path = '$libdir'
+>>#max_expr_depth = 10000         # min 10
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # LOCK MANAGEMENT
+>>#---------------------------------------------------------------------------
+>>
+>>#deadlock_timeout = 1000        # in milliseconds
+>>#max_locks_per_transaction = 64 # min 10, ~260*max_connections bytes
+>> each
+>>
+>>
+>>#---------------------------------------------------------------------------
+>> # VERSION/PLATFORM COMPATIBILITY
+>>#---------------------------------------------------------------------------
+>>
+>># - Previous Postgres Versions -
+>>
+>>#add_missing_from = true
+>>#regex_flavor = advanced        # advanced, extended, or basic
+>>#sql_inheritance = true
+>>
+>># - Other Platforms & Clients -
+>>
+>>#transform_null_equals = false
+>>
+>>
+>>
+>>BUT THE PERFORMANCE IT�S VERY SLOW
+>>
+>>what can do ?????
+>>
+>>Thank
+>>
+>>
+>>Mario Soto
+>>
+>>
+>>
+>>---------------------------(end of
+>> broadcast)--------------------------- TIP 2: you can get off all lists
+>> at once with the unregister command
+>>    (send "unregister YourEmailAddressHere" to
+>> majordomo@postgresql.org)
+>>
+
+
+
+
+From pgsql-patches-owner@postgresql.org  Wed May 26 14:21:48 2004
+X-Original-To: pgsql-patches-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Received: from svr1.postgresql.org ([200.46.204.71])
+	by localhost (neptune.hub.org [200.46.204.2]) (amavisd-new, port 10024)
+	with ESMTP id 67054-06; Wed, 26 May 2004 14:20:56 -0300 (ADT)
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+	Wed, 26 May 2004 17:10:04 GMT
+From: Chris Browne 
+X-Newsgroups: comp.databases.postgresql.performance,
+	comp.databases.postgresql.patches
+Subject: Re: tuning for AIX 5L with large memory
+Date: Wed, 26 May 2004 12:37:24 -0400
+Organization: cbbrowne Computing Inc
+Lines: 53
+Message-ID: <60brkbdu0r.fsf@dev6.int.libertyrms.info>
+References: <40AE8F78.2070901@drivefaster.net>
+	 <40AEBB73.7010105@samurai.com>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
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+	Obscurity, linux)
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+
+neilc@samurai.com (Neil Conway) writes:
+> Christopher Browne wrote:
+>> One of our sysadmins did all the "configuring OS stuff" part; I don't
+>> recall offhand if there was a need to twiddle something in order to
+>> get it to have great gobs of shared memory.
+>
+> FWIW, the section on configuring kernel resources under various
+> Unixen[1] doesn't have any documentation for AIX. If someone out there
+> knows which knobs need to be tweaked, would they mind sending in a doc
+> patch? (Or just specifying what needs to be done, and I'll add the
+> SGML.)
+
+After verifying that nobody wound up messing with the kernel
+parameters, here's a docs patch...
+
+Index: runtime.sgml
+===================================================================
+RCS file: /projects/cvsroot/pgsql-server/doc/src/sgml/runtime.sgml,v
+retrieving revision 1.263
+diff -c -u -r1.263 runtime.sgml
+--- runtime.sgml	29 Apr 2004 04:37:09 -0000	1.263
++++ runtime.sgml	26 May 2004 16:35:43 -0000
+@@ -3557,6 +3557,26 @@
+       
+      
+ 
++     
++      AIX
++      AIXIPC configuration
++      
++       
++        At least as of version 5.1, it should not be necessary to do
++        any special configuration for such parameters as
++        SHMMAX, as it appears this is configured to
++        allow all memory to be used as shared memory.  That is the
++        sort of configuration commonly used for other databases such
++        as DB/2.
++
++        It may, however, be necessary to modify the global
++       ulimit information in
++       /etc/security/limits, as the default hard
++       limits for filesizes (fsize) and numbers of
++       files (nofiles) may be too low.
++       
++      
++           
+ 
+      
+       Solaris
+-- 
+select 'cbbrowne' || '@' || 'acm.org';
+http://www.ntlug.org/~cbbrowne/linuxxian.html
+Hail to the sun god, he sure is a fun god, Ra, Ra, Ra!! 
+
+From pgsql-performance-owner@postgresql.org  Wed May 26 14:21:36 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+	for pgsql-performance@postgresql.org; Wed, 26 May 2004 17:10:05 GMT
+From: Chris Browne 
+X-Newsgroups: comp.databases.postgresql.performance
+Subject: Re: tuning for AIX 5L with large memory
+Date: Wed, 26 May 2004 12:58:55 -0400
+Organization: cbbrowne Computing Inc
+Lines: 58
+Message-ID: <60wu2zcegg.fsf@dev6.int.libertyrms.info>
+References: <40AE8F78.2070901@drivefaster.net>
+	
+	<40B01AD1.1050708@drivefaster.net>
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+
+fbsd@drivefaster.net (Dan Harris) writes:
+> Christopher Browne wrote:
+>
+>>We have a couple of these at work; they're nice and fast, although the
+>>process of compiling things, well, "makes me feel a little unclean."
+>>
+> Thanks very much for your detailed reply, Christopher.  Would you mind
+> elaborating on the "makes me feel a little unclean" statement? 
+
+The way AIX manages symbol tables for shared libraries is fairly
+astounding in its verbosity.
+
+Go and try to compile, by hand, a shared library, and you'll see :-).
+
+> Also, I'm curious which models you are running and if you have any
+> anecdotal comparisons for perfomance?  I'm completely unfamiliar
+> with AIX, so if there are dark corners that await me, I'd love to
+> hear a little more so I can be prepared.  I'm going out on a limb
+> here and jumping to an unfamiliar architecture as well as OS, but
+> the IO performance of these systems has convinced me that it's what
+> I need to break out of my I/O limited x86 systems.
+
+It would probably be better for Andrew Sullivan to speak to the
+details on that.  The main focus of comparison has been between AIX
+and Solaris, and the AIX systems have looked generally pretty good.
+
+We haven't yet had AIX under what could be truly assessed as "heavy
+load."  That comes, in part, from the fact that brand-new
+latest-generation pSeries hardware is _way_ faster than three-year-old
+Solaris hardware.  Today's top-of-the-line is faster than what was
+high-end three years ago, so the load that the Sun boxes can cope with
+"underwhelms" the newer IBM hardware :-).
+
+> I suppose when I do get it, I'll just experiment with different
+> sizes of shared memory and run some benchmarks.  For the price of
+> these things, they better be some good marks!
+
+Well, there's more than one way of looking at these things.  One of
+the important perspectives to me is the one of reliability.  A system
+that is Way Fast, but which crashes once in a while with some hardware
+fault is no good.
+
+I have been getting accustomed to Sun and Dell systems crashing way
+too often :-(.  One of the merits of the pSeries hardware is that it's
+got the maturity of IBM's long term experience at building reliable
+servers.  If the IBM hardware was a bit slower (unlikely, based on it
+being way newer than the older Suns), but had suitable reliability,
+that would seem a reasonable tradeoff to me.
+
+I take the very same perspective on the discussions of "which
+filesystem is best?"  Raw speed is NOT the only issue; it is
+secondary, as far as I am concerned, to "Is It Reliable?"
+-- 
+(format nil "~S@~S" "cbbrowne" "ntlug.org")
+http://cbbrowne.com/info/lsf.html
+Appendium to  the Rules  of the  Evil Overlord #1:  "I will  not build
+excessively integrated  security-and-HVAC systems. They  may be Really
+Cool, but are far too vulnerable to breakdowns."
+
+From pgsql-general-owner@postgresql.org  Wed May 26 14:47:17 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
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+Date: Wed, 26 May 2004 19:46:32 +0200
+From: Frank Finner 
+To: "Mario Soto" 
+Cc: pgsql-general@postgresql.org
+Subject: Re: performance very slow
+Message-Id: <20040526194632.4c4f9f09.postgresql@finner.de>
+In-Reply-To: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+References: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
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+From pgsql-performance-owner@postgresql.org  Wed May 26 15:00:07 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Date: Wed, 26 May 2004 21:00:34 +0300
+From: Vitaly Belman 
+Reply-To: Vitaly Belman 
+X-Priority: 3 (Normal)
+Message-ID: <3115838500.20040526210034@012.net.il>
+To: Josh Berkus 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: PostgreSQL caching
+In-Reply-To: <200405260917.35537.josh@agliodbs.com>
+References: <20792805375.20040521203337@012.net.il>
+	<40B3C792.3020106@outputservices.com>
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+
+From pgsql-general-owner@postgresql.org  Wed May 26 16:04:22 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Wed, 26 May 2004 21:03:56 +0200 (CEST)
+From: Dennis Bjorklund 
+To: Mario Soto 
+Cc: pgsql-general@postgresql.org
+Subject: Re: performance very slow
+In-Reply-To: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+Message-ID: 
+MIME-Version: 1.0
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+
+On Wed, 26 May 2004, Mario Soto wrote:
+
+> tha machine is a Pentium IV 2,6 GHZ AND 1 GB IN RAM with lINUX RH 9.0.
+> 
+> BUT THE PERFORMANCE IT�S VERY SLOW
+
+How often do you run VACUUM ANALYZE? You might want to do that every night 
+or every hour (depending on how much updates you have).
+
+Some of your config values could and should be tuned, read something like
+
+http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+
+Still, if it's very slow it's probably not just a little tweaking of these
+variables that solves everything.
+
+If that is the case you need to find a slow query, run EXPLAIN ANALYZE on
+it and try to figure out why it is slow. There is a list to help with
+performance issues called pgsql-performance that you might want to post to
+(and read its archive).
+
+But before anything else, make sure you run VACUUM ANALYZE regulary.
+
+-- 
+/Dennis Bj�rklund
+
+
+From pgsql-general-owner@postgresql.org  Wed May 26 16:16:23 2004
+X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Date: Wed, 26 May 2004 15:13:14 -0400 (VET)
+Subject: Re: performance very slow
+From: "Mario Soto" 
+To: 
+In-Reply-To: 
+References: 
+ <36620.200.35.66.77.1085585190.squirrel@mail.venezolanadeavaluos.com>
+	
+X-Priority: 3
+Importance: Normal
+Cc: ,
+	
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+
+OK.
+
+i see the link and  change parameters in postgresql.conf
+
+i.e.
+
+When excecute a insert statement the memory up to 90% to use .
+it's normal ???????
+
+
+Thank for yor help and sorry for my bad englis
+
+Regards
+
+Mario Soto
+
+
+> On Wed, 26 May 2004, Mario Soto wrote:
+>
+>> tha machine is a Pentium IV 2,6 GHZ AND 1 GB IN RAM with lINUX RH 9.0.
+>>
+>> BUT THE PERFORMANCE IT�S VERY SLOW
+>
+> How often do you run VACUUM ANALYZE? You might want to do that every
+> night  or every hour (depending on how much updates you have).
+>
+> Some of your config values could and should be tuned, read something
+> like
+>
+> http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
+>
+> Still, if it's very slow it's probably not just a little tweaking of
+> these variables that solves everything.
+>
+> If that is the case you need to find a slow query, run EXPLAIN ANALYZE
+> on it and try to figure out why it is slow. There is a list to help with
+> performance issues called pgsql-performance that you might want to post
+> to (and read its archive).
+>
+> But before anything else, make sure you run VACUUM ANALYZE regulary.
+>
+> --
+> /Dennis Bj�rklund
+
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 27 10:57:33 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+Message-Id: <200405271356.i4RDuBnb020333@ms-smtp-02.tampabay.rr.com>
+From: "Matthew Nuzum" 
+To: "'Vitaly Belman'" 
+Cc: 
+Subject: Re: PostgreSQL caching
+Date: Thu, 27 May 2004 09:56:00 -0400
+MIME-Version: 1.0
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+
+> 
+> Hello Josh,
+> 
+> JB> Not that you can't improve the query, just that it might not fix
+> JB> the problem.
+> 
+> Yes, I'm aware it might be slower than the Linux version, but then, as
+> you said, I still can improve the query (as I did with your help now).
+> 
+> But true, if there's something awfully wrong with Win32 port
+> performance, I might be doing some overwork...
+> 
+> JB> Therefore ... your detailed feedback is appreciated, especially if you
+> can
+> JB> compare stuff to the same database running on a Linux, Unix, or BSD
+> machine.
+> 
+> I can't easily install Linux right now.. But I am considering using it
+> through VMWare. Do you think it would suffice as a comprasion?
+> 
+> From what I saw (e.g
+> http://usuarios.lycos.es/hernandp/articles/vpcvs.html) the performance
+> are bad only when it's coming to graphics, otherwise it looks pretty
+> good.
+> 
+> Regards,
+>  Vitaly Belman
+> 
+
+An interesting alternative that I've been using lately is colinux
+(http://colinux.sf.net).  It lets you run linux in windows and compared to
+vmware, I find it remarkably faster and when it is idle less resource
+intensive.  I have vmware but if I'm only going to use a console based
+program, colinux seems to outperform it.  
+
+Note that it may simply be interactive processes that run better because it
+has a simpler interface and does not try to emulate the display hardware.
+(Therefore no X unless you use vmware)  It seems though that there is less
+overhead and if that's the case, then everything should run faster.
+
+Also note that getting it installed is a little more work than vmware.  If
+you're running it on a workstation that you use for normal day-to-day tasks
+though I think you'll like it because you can detach the terminal and let it
+run in the background.  When I do that I often forget it is running because
+it produces such a low load on the system.  If you are going to give it a
+try, the one trick I used to get things going was to download the newest
+beta of winpcap and then the networking came up easily.  Everything else was
+a piece of cake.
+
+Matthew Nuzum		| Makers of "Elite Content Management System"
+www.followers.net		| View samples of Elite CMS in action
+matt@followers.net	| http://www.followers.net/portfolio/
+
+
+
+From pgsql-performance-owner@postgresql.org  Thu May 27 19:41:13 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
+Received: from localhost (unknown [200.46.204.2])
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+Message-ID: <40B66E71.7060703@drivefaster.net>
+Date: Thu, 27 May 2004 16:40:49 -0600
+From: Dan Harris 
+User-Agent: Mozilla Thunderbird 0.6 (Macintosh/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: pgsql-performance@postgresql.org
+Subject: Hardware opinions wanted
+Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+Content-Transfer-Encoding: 7bit
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+
+I wanted to solicit some opinions on architecture and performance from 
+you guys.
+
+I am torn right now between these two systems to replace my aging DB server:
+
+4 x 2.2 GHz Opteron
+8GB RAM
+Ultra320 15kRPM RAID5 with 128MB cache
+
+and
+
+2-way 1.2GHz POWER4+ IBM pSeries 615
+8GB RAM
+Ultra320 15kRPM RAID5 with 64MB cache
+
+I plan on serving ~80GB of pgsql database on this machine.  The current 
+machine handles around 1.5 million queries per day.
+
+I am having some trouble finding direct comparisons between the two 
+architectures.  The OS will most likely be Linux ( I'm hedging on AIX 
+for now ).  The pSeries has 8MB cache per CPU card ( 2 CPU on a card ) 
+while the Opteron has 1MB for each processor.  I know the POWER4+ is a 
+very fast machine but I wonder if having more processors in the Opteron 
+system would beat it for database serving? FWIW, they are very close in 
+price.
+
+Ignoring the fault-tolerance features of the pSeries, which one would 
+you pick for performance?
+
+Thanks,
+Dan
+
+From pgsql-performance-owner@postgresql.org  Fri May 28 07:43:25 2004
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+Message-ID: <40B717BF.9060507@turtle-entertainment.de>
+Date: Fri, 28 May 2004 12:43:11 +0200
+From: Bjoern Metzdorf 
+User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502)
+X-Accept-Language: en-us, en
+MIME-Version: 1.0
+To: Dan Harris 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Hardware opinions wanted
+References: <40B66E71.7060703@drivefaster.net>
+In-Reply-To: <40B66E71.7060703@drivefaster.net>
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+
+Dan Harris wrote:
+> I am torn right now between these two systems to replace my aging DB 
+> server:
+> 
+> 4 x 2.2 GHz Opteron
+> 8GB RAM
+> Ultra320 15kRPM RAID5 with 128MB cache
+> 
+> and
+> 
+> 2-way 1.2GHz POWER4+ IBM pSeries 615
+> 8GB RAM
+> Ultra320 15kRPM RAID5 with 64MB cache
+
+I don't know anything about the pSeries, but have a look in the 
+archives, there was recently a rather long thread about Xeon vs. 
+Opteron. The Opteron was the clear winner.
+
+Personally I think that you can't be wrong with the 4-way Opteron. It 
+scales very well and if you don't need the fault tolerance of the 
+pSeries platform, then you should be able to save one or two bucks with 
+opteron way.
+
+Btw: If you want to save a few more bucks, then drop the 15k and take 
+10k drives. They are of almost same speed.
+
+Regards,
+Bjoern
+
+
+
+From pgsql-performance-owner@postgresql.org  Sat May 29 02:06:34 2004
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+	Sat, 29 May 2004 01:06:06 -0400 (EDT)
+To: Josh Sacks 
+Cc: pgsql-performance@postgresql.org
+Subject: Re: Not using Primary Key in query 
+In-reply-to:  
+References: 
+Comments: In-reply-to Josh Sacks 
+	message dated "Tue, 25 May 2004 11:37:55 -0700"
+Date: Sat, 29 May 2004 01:06:05 -0400
+Message-ID: <15004.1085807165@sss.pgh.pa.us>
+From: Tom Lane 
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+
+Josh Sacks  writes:
+> I can't understand what's going on in this simple query:
+
+If you are using anything older than PG 7.4, you should not expect good
+performance from WHERE ... IN (sub-SELECT) queries.  There's essentially
+no optimization happening there.
+
+			regards, tom lane
+
+From pgsql-performance-owner@postgresql.org  Sat May 29 04:04:54 2004
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+	for pgsql-performance@postgresql.org; Sat, 29 May 2004 02:28:38 -0400
+From: "rajaguru" 
+To: 
+Subject: Logging all query in one seperate File
+Date: Sat, 29 May 2004 09:28:35 +0300
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+
+Hai all,
+
+          I want to log my queries send to the Postgresql server. I heard
+that we can do this my specifying the file name in 
+
+/etc/rc.d/init.d/Postgresql  initiating file. But I don't know. If this is
+the way means how to do that. Or anyother way is there.
+
+ 
+
+Thanks is advance
+
+Raja  
+
+
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+
+
+
+
+
+
+
+
+
+
+
+

+
+
Hai all,

+
+
          I=
+ want to log my queries send to the Postgresql
+server. I heard that we can do this my specifying the file name in 

+
+
/etc/rc.d/init.d/Postgresql  initiating file. But I=
+ don’t
+know. If this is the way means how to do that. Or anyother way is there.

+
+
 

+
+
Thanks is advance

+
+
Raja  

+
+

+
+
+
+
+
+------=_NextPart_000_0000_01C4455F.52C5F050--
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+
+From pgsql-performance-owner@postgresql.org  Sat May 29 06:31:58 2004
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+	Sat, 29 May 2004 15:01:50 +0530
+From: Shridhar Daithankar 
+Reply-To: shridhar@frodo.hserus.net
+To: share-postgres@think42.com
+Subject: Re: filesystem option tuning
+Date: Sat, 29 May 2004 15:01:45 +0530
+User-Agent: KMail/1.6.1
+Cc: Richard Huxton ,
+	pgsql-performance@postgresql.org
+References: <20040515125227.A29574@p15097255.pureserver.info>
+	<40A8F0B6.6060703@archonet.com>
+	<20040519093239.A26016@p15097255.pureserver.info>
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+
+On Wednesday 19 May 2004 13:02, share-postgres@think42.com wrote:
+> >   - If you can put WAL on separate disk(s), all the better.
+>
+> Does that mean only the xlog, or also the clog? As far as I understand, the
+> clog contains some meta-information on the xlog, so presumably it is
+> flushed to disc synchronously together with the xlog? That would mean that
+> they each need a separate disk to prevent one disk having to seek too
+> often...?
+
+You can put clog and xlog on same drive. That should be enough in most cases. 
+xlog is written sequentially and never read back other than for recovery 
+after a crash. clog is typically 8KB or a page and should not be an IO 
+overhead even in high traffic databases.
+
+> >   - Battery-backed write-cache for your SCSI controller can be a big
+> > performance win
+>
+> I probably won't be able to get such a setup for this project; that's why I
+> am bothering about which disk will be seeking how often.
+
+As I said earlier, xlog is written sequentially and if I am not mistaken clog 
+as well. So there should not be much seeking if they are on a separate drive.
+
+(Please correct me if I am wrong)
+
+> >   - Tablespaces _should_ be available in the next release of PG, we'll
+> > know for sure soon. That might make life simpler for you if you do want
+> > to spread your database around by hand,
+>
+> Ok, I think tablespaces are not the important thing - at least for this
+> project of ours.
+
+Well, if you have tablespaces, you don't have to mess with symlinking 
+clog/xlog or use location facility which is bit rough. You should be able to 
+manage such a setup solely from postgresql. That is an advantage of 
+tablespaces.
+
+> Here goes ... we are talking about a database cluster with two tables where
+> things are happening, one is a kind of log that is simply "appended" to and
+> will expect to reach a size of several million entries in the time window
+> that is kept, the other is a persistent backing of application data that
+> will mostly see read-modify-writes of single records. Two writers to the
+> history, one writer to the data table. The volume of data is not very high
+> and RAM is enough...
+
+Even if you have enough RAM, you should use pg_autovacuum so that your tables 
+are in shape. This is especially required when your update/insert rate is 
+high.
+
+If your history logs needs to be rotated, you can take advantage of the fact 
+that DDL's in postgresql are fully transacted. So you can drop the table in a 
+transaction but nobody will notice anything unless it is committed. Makes a 
+transparent rotation.
+
+HTH
+
+ Shridhar
+
+From pgsql-performance-owner@postgresql.org  Sat May 29 15:31:33 2004
+X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org
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+To: shridhar@frodo.hserus.net
+Cc: share-postgres@think42.com, Richard Huxton ,
+	pgsql-performance@postgresql.org
+Subject: Re: filesystem option tuning 
+In-reply-to: <200405291501.45229.shridhar@frodo.hserus.net> 
+References: <20040515125227.A29574@p15097255.pureserver.info>
+	<40A8F0B6.6060703@archonet.com>
+	<20040519093239.A26016@p15097255.pureserver.info>
+	<200405291501.45229.shridhar@frodo.hserus.net>
+Comments: In-reply-to Shridhar Daithankar 
+	message dated "Sat, 29 May 2004 15:01:45 +0530"
+Date: Sat, 29 May 2004 11:18:06 -0400
+Message-ID: <20195.1085843886@sss.pgh.pa.us>
+From: Tom Lane 
+X-Virus-Scanned: by amavisd-new at postgresql.org
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+
+Shridhar Daithankar  writes:
+> On Wednesday 19 May 2004 13:02, share-postgres@think42.com wrote:
+> - If you can put WAL on separate disk(s), all the better.
+>> 
+>> Does that mean only the xlog, or also the clog?
+
+> You can put clog and xlog on same drive.
+
+You can, but I think you shouldn't.  The entire argument for giving xlog
+its own drive revolves around the fact that xlog is written
+sequentially, and so if it has its own spindle then you have near-zero
+seek requirements.  As soon as you give that drive any other work to do,
+you start losing the low-seek property.
+
+Now as Shridhar says, clog is not a very high-I/O-volume thing, so in
+one sense it doesn't much matter which drive you put it on.  But it
+seems to me that clog acts much more like ordinary table files than it
+acts like xlog.
+
+			regards, tom lane
+