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 519C2528E7 for ; Sat, 20 Aug 2005 09:23:07 -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 90582-06 for ; Sat, 20 Aug 2005 12:23:03 +0000 (GMT) Received: from vms046pub.verizon.net (vms046pub.verizon.net [206.46.252.46]) by svr1.postgresql.org (Postfix) with ESMTP id ACB5452849 for ; Sat, 20 Aug 2005 09:23:02 -0300 (ADT) Received: from osgiliath.mathom.us ([70.108.53.154]) by vms046.mailsrvcs.net (Sun Java System Messaging Server 6.2 HotFix 0.04 (built Dec 24 2004)) with ESMTPA id <0ILI0044IT2H0RD6@vms046.mailsrvcs.net> for pgsql-performance@postgresql.org; Sat, 20 Aug 2005 07:23:06 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id 91A3B6050CD for ; Sat, 20 Aug 2005 08:23:05 -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 27694-05 for ; Sat, 20 Aug 2005 08:23:05 -0400 (EDT) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id 5F459600498; Sat, 20 Aug 2005 08:23:05 -0400 (EDT) Date: Sat, 20 Aug 2005 08:23:05 -0400 From: Michael Stone Subject: Re: extremly low memory usage In-reply-to: <43071162.6050405@kolumbus.fi> To: pgsql-performance@postgresql.org Mail-Followup-To: pgsql-performance@postgresql.org Message-id: <20050820122305.GN19080@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: <1124386761.27881.119.camel@bluejay.goodinassociates.com> <4304CB77.4070403@arbash-meinel.com> <1124470109.27881.152.camel@bluejay.goodinassociates.com> <43061472.2080201@arbash-meinel.com> <6.2.3.4.0.20050819140714.05c181e8@pop.earthlink.net> <43063196.9000001@arbash-meinel.com> <1124485299.27881.192.camel@bluejay.goodinassociates.com> <43071162.6050405@kolumbus.fi> User-Agent: Mutt/1.5.9i X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.005 required=5 tests=[AWL=0.005] X-Spam-Level: X-Archive-Number: 200508/292 X-Sequence-Number: 14039 On Sat, Aug 20, 2005 at 02:17:54PM +0300, Marko Ristola wrote: >Based on my knoledge, Ext3 is good with keeping filesystem integrity >AND data integrity while pressing the reset button. However, by >selecting data=writeback, you gain more speed, but you risk the data >integrity during a crash: Ext3 garantees only filesystem integrity. That's why postgres keeps its own transaction log. Any of these filesystems guarantee data integrity for data that's been synced to disk, and postgres keeps track of what data has and has not been committed so it can recover gracefully from a failure. That's why most filesystems are designed the way they are; the application can determine what things need better data integrity and which need better performance on a case-by-case basis. Mike Stone