X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 960949DD633 for ; Mon, 12 Dec 2005 13:48:53 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 10572-05 for ; Mon, 12 Dec 2005 13:48:52 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from mx2.surnet.cl (mx2.surnet.cl [216.155.73.181]) by postgresql.org (Postfix) with ESMTP id 2720B9DD5A1 for ; Mon, 12 Dec 2005 13:48:49 -0400 (AST) Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) by mx2.surnet.cl with ESMTP; 12 Dec 2005 10:25:47 -0300 X-IronPort-AV: i="3.99,243,1131332400"; d="scan'208"; a="774879:sNHT15084776" Received: from alvh.no-ip.org (201.220.122.65) by cluster.surnet.cl (7.0.043) (authenticated as alvherre@surnet.cl) id 438E66E800136FEA; Mon, 12 Dec 2005 10:23:19 -0300 Received: by alvh.no-ip.org (Postfix, from userid 1000) id 9C5F7C37221; Mon, 12 Dec 2005 10:23:42 -0300 (CLST) Date: Mon, 12 Dec 2005 10:23:42 -0300 From: Alvaro Herrera To: Michael Fuhr Cc: Carlos Benkendorf , pgsql-performance@postgresql.org Subject: Re: How much expensive are row level statistics? Message-ID: <20051212132342.GE19555@surnet.cl> Mail-Followup-To: Michael Fuhr , Carlos Benkendorf , pgsql-performance@postgresql.org References: <20051211115336.91041.qmail@web35506.mail.mud.yahoo.com> <20051211194442.GA97174@winnie.fuhr.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051211194442.GA97174@winnie.fuhr.org> User-Agent: Mutt/1.5.11 X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=1.531 required=5 tests=[AWL=-0.388, DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44] X-Spam-Score: 1.531 X-Spam-Level: * X-Archive-Number: 200512/293 X-Sequence-Number: 16114 Michael Fuhr wrote: > On Sun, Dec 11, 2005 at 11:53:36AM +0000, Carlos Benkendorf wrote: > > I would like to use autovacuum but is not too much expensive > > collecting row level statistics? > > The cost depends on your usage patterns. I did tests with one of > my applications and saw no significant performance difference for > simple selects, but a series of insert/update/delete operations ran > about 30% slower when block- and row-level statistics were enabled > versus when the statistics collector was disabled. This series of i/u/d operations ran with no sleep in between, right? I wouldn't expect a normal OLTP operation to be like this. (If it is you have a serious shortage of hardware ...) -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support