Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id BAEBC9FB3D3 for ; Fri, 6 Jul 2007 11:40:43 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 87167-09 for ; Fri, 6 Jul 2007 11:40:30 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from lists.commandprompt.com (host-254.commandprompt.net [207.173.203.254]) by postgresql.org (Postfix) with ESMTP id 798DC9FB3A2 for ; Fri, 6 Jul 2007 11:40:39 -0300 (ADT) Received: from perhan.alvh.no-ip.org (201-221-218-82.bk12-dsl.surnet.cl [201.221.218.82]) (authenticated bits=0) by lists.commandprompt.com (8.13.7/8.13.6) with ESMTP id l66Eecj0018017; Fri, 6 Jul 2007 07:40:38 -0700 Received: by perhan.alvh.no-ip.org (Postfix, from userid 1000) id DBA7547C44; Fri, 6 Jul 2007 10:40:35 -0400 (CLT) Date: Fri, 6 Jul 2007 10:40:35 -0400 From: Alvaro Herrera To: lai yoke hman Cc: pgsql-performance@postgresql.org Subject: Re: Direct I/O Message-ID: <20070706144035.GF5797@alvh.no-ip.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) X-Virus-Scanned: ClamAV 0.90.3/3607/Thu Jul 5 16:51:19 2007 on projects.commandprompt.com X-Virus-Status: Clean X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by milter-greylist-1.6 (lists.commandprompt.com [192.168.2.159]); Fri, 06 Jul 2007 07:40:39 -0700 (PDT) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200707/47 X-Sequence-Number: 25731 lai yoke hman wrote: > How can I know my PostgreSQL 8 is using direct I/O or buffered I/O? If > using buffered I/O, how can I enable direct I/O? What is the > performance difference of them? 1. it is buffered 2. you can't 3. there isn't any because there isn't direct I/O Unless you mess with the filesystem features, at which point I shut up or they shut me down. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.