X-Original-To: pgsql-performance-postgresql.org@postgresql.org Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id EAA869FA68D for ; Sun, 23 Jul 2006 08:29:23 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 43562-01 for ; Sun, 23 Jul 2006 08:29:17 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from vms048pub.verizon.net (vms048pub.verizon.net [206.46.252.48]) by postgresql.org (Postfix) with ESMTP id 3D7A79FA6B5 for ; Sun, 23 Jul 2006 08:07:31 -0300 (ADT) Received: from osgiliath.mathom.us ([72.66.113.236]) by vms048.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 (built Sep 9 2005)) with ESMTPA id <0J2U0045IS8IR9O9@vms048.mailsrvcs.net> for pgsql-performance@postgresql.org; Sun, 23 Jul 2006 06:07:30 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id 45CAA6E796 for ; Sun, 23 Jul 2006 07:07:29 -0400 (EDT) Received: from osgiliath.mathom.us ([127.0.0.1]) by localhost (osgiliath.home.mathom.us [127.0.0.1]) (amavisd-new, port 10024) with LMTP id Rlm+N4sQB+Kl for ; Sun, 23 Jul 2006 07:07:27 -0400 (EDT) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id B44026F875; Sun, 23 Jul 2006 07:07:26 -0400 (EDT) Date: Sun, 23 Jul 2006 07:07:26 -0400 From: Michael Stone Subject: Re: Forcing using index instead of sequential scan? In-reply-to: <44C25FDD.8070003@modgraph-usa.com> To: pgsql-performance@postgresql.org Mail-followup-to: pgsql-performance@postgresql.org Message-id: <20060723110724.GU8069@mathom.us> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii; format=flowed Content-disposition: inline X-Virus-Scanned: Debian amavisd-new at mathom.us X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 References: <26827.1153585341@sss.pgh.pa.us> <44C25FDD.8070003@modgraph-usa.com> User-Agent: Mutt/1.5.11+cvs20060403 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.134 tagged_above=0 required=5 tests=FORGED_RCVD_HELO, SPF_PASS X-Spam-Level: X-Archive-Number: 200607/225 X-Sequence-Number: 20085 On Sat, Jul 22, 2006 at 10:26:53AM -0700, Craig A. James wrote: >This causes massive file-system activity and flushes all files that the >kernel has cached. If you run this between each Postgres test (let it run >for a couple minutes), it gives you an apples-to-apples comparison between >successive benchmarks, and eliminates the effects of caching. Assuming a system with small ram or an unusually large system installation. Unmounting is a much more realiable mechanism. Mike Stone