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 042859DCA20 for ; Fri, 16 Dec 2005 22:44:20 -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 04260-05 for ; Fri, 16 Dec 2005 22:44:24 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from rwcrmhc12.comcast.net (rwcrmhc12.comcast.net [216.148.227.152]) by postgresql.org (Postfix) with ESMTP id E679F9DC9F0 for ; Fri, 16 Dec 2005 22:44:17 -0400 (AST) Received: from candle.pha.pa.us (unknown[71.225.87.206](misconfigured sender)) by comcast.net (rwcrmhc12) with ESMTP id <20051217024417014008f180e>; Sat, 17 Dec 2005 02:44:21 +0000 Received: (from pgman@localhost) by candle.pha.pa.us (8.11.6/8.11.6) id jBH2iJV11094; Fri, 16 Dec 2005 21:44:19 -0500 (EST) From: Bruce Momjian Message-Id: <200512170244.jBH2iJV11094@candle.pha.pa.us> Subject: Re: How much expensive are row level statistics? In-Reply-To: <1667.1134444045@sss.pgh.pa.us> To: Tom Lane Date: Fri, 16 Dec 2005 21:44:19 -0500 (EST) CC: Michael Fuhr , Merlin Moncure , pgsql-performance@postgresql.org, Carlos Benkendorf X-Mailer: ELM [version 2.4ME+ PL121 (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.087 required=5 tests=[AWL=0.087] X-Spam-Score: 0.087 X-Spam-Level: X-Archive-Number: 200512/418 X-Sequence-Number: 16239 Tom Lane wrote: > Michael Fuhr writes: > > Further tests show that for this application > > the killer is stats_command_string, not stats_block_level or > > stats_row_level. > > I tried it with pgbench -c 10, and got these results: > 41% reduction in TPS rate for stats_command_string Woh, 41%. That's just off the charts! What are we doing internally that would cause 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