Received: from localhost (maia-5.hub.org [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id 6F2A29FA6B0 for ; Sat, 6 Jan 2007 15:46:47 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-new, port 10024) with ESMTP id 08156-06 for ; Sat, 6 Jan 2007 15:46:40 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 834849FA31B for ; Sat, 6 Jan 2007 15:46:42 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id l06JkexE017825; Sat, 6 Jan 2007 14:46:40 -0500 (EST) To: Daryl Herzmann cc: pgsql-performance@postgresql.org Subject: Re: Missing the point of autovacuum In-reply-to: References: Comments: In-reply-to Daryl Herzmann message dated "Sat, 06 Jan 2007 12:59:03 -0600" Date: Sat, 06 Jan 2007 14:46:40 -0500 Message-ID: <17824.1168112800@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200701/79 X-Sequence-Number: 22680 Daryl Herzmann writes: > As the months have gone by, I notice many of my tables having *lots* of > unused item pointers. For example, > There were 31046438 unused item pointers. > Total free space (including removable row versions) is 4894537260 bytes. > 580240 pages are or will become empty, including 7 at the end of the > table. > 623736 pages containing 4893544876 free bytes are potential move > destinations. This definitely looks like autovac is not getting the job done for you. The default autovac settings in 8.1 are very un-aggressive and many people find that they need to change the settings to make autovac vacuum more often. Combining autovac with the traditional approach of a cron job isn't a bad idea, either, if you have known slow times of day --- autovac doesn't currently have any concept of a maintenance window, so if you'd rather your vacuuming mostly happened at 2AM, you still need a cron job for that. regards, tom lane