Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 0D2E02E2FB4 for ; Sun, 27 Jan 2008 06:48:21 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 84526-02 for ; Sun, 27 Jan 2008 06:48:07 -0400 (AST) Received: from mail01.enterprisedb.com (mail01.enterprisedb.com [63.246.7.168]) by postgresql.org (Postfix) with ESMTP id 023C12E2FB7 for ; Sun, 27 Jan 2008 06:48:10 -0400 (AST) thread-index: Achg0i0/H/vFz6OsRR+cbAPGvV986Q== Received: from [192.168.1.33] ([82.3.239.162]) by mail01.enterprisedb.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Sun, 27 Jan 2008 05:48:39 -0500 Content-Class: urn:content-classes:message Importance: normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.4133 Message-ID: <479C6142.9060502@enterprisedb.com> Date: Sun, 27 Jan 2008 10:47:30 +0000 From: "Heikki Linnakangas" Organization: EnterpriseDB User-Agent: Icedove 1.5.0.14pre (X11/20071020) MIME-Version: 1.0 To: "Matthew" Cc: "Greg Smith" , "David Brain" , Subject: Re: 1 or 2 servers for large DB scenario. References: In-Reply-To: Content-Type: text/plain; format=flowed; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 27 Jan 2008 10:48:39.0781 (UTC) FILETIME=[2D338950:01C860D2] X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/245 X-Sequence-Number: 28484 Matthew wrote: > On Fri, 25 Jan 2008, Greg Smith wrote: >> If you're seeing <100TPS you should consider if it's because you're >> limited by how fast WAL commits can make it to disk. If you really >> want good insert performance, there is no substitute for getting a >> disk controller with a good battery-backed cache to work around that. >> You could just put the WAL xlog directory on a RAID-1 pair of disks to >> accelerate that, you don't have to move the whole database to a new >> controller. > > Hey, you *just* beat me to it. > > Yes, that's quite right. My suggestion was to move the whole thing, but > Greg is correct - you only need to put the WAL on a cached disc system. > That'd be quite a bit cheaper, I'd imagine. > > Another case of that small SSD drive being useful, I think. PostgreSQL 8.3 will have "asynchronous commits" feature, which should eliminate that bottleneck without new hardware, if you can accept the loss of last few transaction commits in case of sudden power loss: http://www.postgresql.org/docs/8.3/static/wal-async-commit.html -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com