X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 49DD2D70FF for ; Tue, 23 Aug 2005 17:29:36 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 91328-06 for ; Tue, 23 Aug 2005 20:29:34 +0000 (GMT) Received: from vms044pub.verizon.net (vms044pub.verizon.net [206.46.252.44]) by svr1.postgresql.org (Postfix) with ESMTP id D9389D6FD9 for ; Tue, 23 Aug 2005 17:29:32 -0300 (ADT) Received: from osgiliath.mathom.us ([151.200.14.55]) by vms044.mailsrvcs.net (Sun Java System Messaging Server 6.2 HotFix 0.04 (built Dec 24 2004)) with ESMTPA id <0ILO00DQIZL92XE1@vms044.mailsrvcs.net> for pgsql-performance@postgresql.org; Tue, 23 Aug 2005 15:29:34 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id 2B048602638; Tue, 23 Aug 2005 16:29:33 -0400 (EDT) Received: from osgiliath.mathom.us ([127.0.0.1]) by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 04490-02; Tue, 23 Aug 2005 16:29:32 -0400 (EDT) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id D9B07600162; Tue, 23 Aug 2005 16:29:32 -0400 (EDT) Date: Tue, 23 Aug 2005 16:29:32 -0400 From: Michael Stone Subject: Re: Caching by Postgres In-reply-to: <200508231238.04844.josh@agliodbs.com> To: Josh Berkus Cc: pgsql-performance@postgresql.org Mail-Followup-To: Josh Berkus , pgsql-performance@postgresql.org Message-id: <20050823202932.GK8667@mathom.us> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii; format=flowed Content-disposition: inline X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us References: <20050823171045.12112.qmail@web51309.mail.yahoo.com> <20050823124323.710a9dd3.frank@wiles.org> <430B6DE3.6040109@sun.com> <200508231238.04844.josh@agliodbs.com> User-Agent: Mutt/1.5.10i X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.05 required=5 tests=[FORGED_RCVD_HELO=0.05] X-Spam-Level: X-Archive-Number: 200508/354 X-Sequence-Number: 14101 On Tue, Aug 23, 2005 at 12:38:04PM -0700, Josh Berkus wrote: >which have a clear and measurable effect on performance and are fixable >without bloating the PG code. Some of these issues (COPY path, context >switching Does that include increasing the size of read/write blocks? I've noticed that with a large enough table it takes a while to do a sequential scan, even if it's cached; I wonder if the fact that it takes a million read(2) calls to get through an 8G table is part of that. Mike Stone