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 1A3B99DCAEF for ; Sun, 11 Dec 2005 15:44:49 -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 22947-06 for ; Sun, 11 Dec 2005 15:44:49 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) by postgresql.org (Postfix) with ESMTP id E4BE09DCAC3 for ; Sun, 11 Dec 2005 15:44:46 -0400 (AST) Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jBBJii9F083083 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 11 Dec 2005 12:44:46 -0700 (MST) (envelope-from mfuhr@winnie.fuhr.org) Received: from winnie.fuhr.org (localhost [127.0.0.1]) by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jBBJihI1097345; Sun, 11 Dec 2005 12:44:43 -0700 (MST) (envelope-from mfuhr@winnie.fuhr.org) Received: (from mfuhr@localhost) by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jBBJihAm097344; Sun, 11 Dec 2005 12:44:43 -0700 (MST) (envelope-from mfuhr) Date: Sun, 11 Dec 2005 12:44:43 -0700 From: Michael Fuhr To: Carlos Benkendorf Cc: pgsql-performance@postgresql.org Subject: Re: How much expensive are row level statistics? Message-ID: <20051211194442.GA97174@winnie.fuhr.org> References: <20051211115336.91041.qmail@web35506.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051211115336.91041.qmail@web35506.mail.mud.yahoo.com> X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.023 required=5 tests=[AWL=0.023] X-Spam-Score: 0.023 X-Spam-Level: X-Archive-Number: 200512/281 X-Sequence-Number: 16102 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. -- Michael Fuhr