Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 4BE292E07DD for ; Sun, 18 Nov 2007 10:29:39 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 60545-05 for ; Sun, 18 Nov 2007 10:29:34 -0400 (AST) Received: from outmail136011.authsmtp.com (outmail136011.authsmtp.com [62.13.136.11]) by postgresql.org (Postfix) with ESMTP id 080562E0D6A for ; Sun, 18 Nov 2007 10:29:33 -0400 (AST) Received: from outmail128179.authsmtp.co.uk (outmail128179.authsmtp.co.uk [62.13.128.179]) by punt3.authsmtp.com (8.13.8/8.13.8/Kp) with ESMTP id lAIETPSi083426; Sun, 18 Nov 2007 14:29:25 GMT Received: from [192.168.0.3] (85-211-24-246.dyn.gotadsl.co.uk [85.211.24.246]) (authenticated bits=0) by mail.authsmtp.com (8.13.8/8.13.8/Kp) with ESMTP id lAIETMk1061689; Sun, 18 Nov 2007 14:29:23 GMT Subject: Re: work_mem and shared_buffers From: Simon Riggs To: Scott Marlowe Cc: "Campbell, Lance" , Heikki Linnakangas , pgsql-performance@postgresql.org In-Reply-To: References: <47349F4E.5070204@enterprisedb.com> Content-Type: text/plain Date: Sun, 18 Nov 2007 14:29:39 +0000 Message-Id: <1195396179.4217.1.camel@ebony.site> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit X-Server-Quench: a86a0d4c-95e2-11dc-b86a-001185d377ca X-AuthRoute: OCdxZQATClZOTQEd DAteCiNZVAwpPBRK HVkIKg5MJUcNSQVJ NksacxtFaQ1bY1ZH HGQLW1NEUVl7W2p/ aQkfZQBDYEtPQQdu TkpNRE1QERpoT0Bw f2t6L0JzdwNHfnZ5 K0dgWXAVDUx8JEYp Rh1JHGhTZ3phaTRM TRJQcVJJcANLfxdA PlN4UyBcLwdSbGoL JyIJERcLGAAXNyNP QTYIIFdaSEAHViU8 TgoPEQIlAEMLSj8o RyAn X-Authentic-SMTP: 61633235383639.squirrel.dmpriest.net.uk:752/Kp X-Report-SPAM: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-Virus-Status: No virus detected - but ensure you scan with your own anti-virus system! X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200711/255 X-Sequence-Number: 27670 On Fri, 2007-11-09 at 13:12 -0600, Scott Marlowe wrote: > Note that my best time was at around 16 Meg work_mem. This data set > is MUCH bigger than 16 Meg, it's around 300-400 Meg. But work_mem > optimized out at 16 Meg. Btw, I tried it going as high as 768 Meg, > and it was still slower than 16M. Remember that what you have shown is that for *this* dataset 16Mb is the optimum value. It is not a recommended value for all cases. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com