Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id C674A2E0081 for ; Fri, 18 Jan 2008 06:58:08 -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 61161-04 for ; Fri, 18 Jan 2008 06:57:51 -0400 (AST) Received: from cptwks26.careerjunction.local (unknown [196.212.105.173]) by postgresql.org (Postfix) with ESMTP id E281D2E0090 for ; Fri, 18 Jan 2008 06:57:59 -0400 (AST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by cptwks26.careerjunction.local (Postfix) with ESMTP id D4C04B7A4B for ; Fri, 18 Jan 2008 12:58:07 +0200 (SAST) Message-ID: <4790863E.4000309@careerjunction.co.za> Date: Fri, 18 Jan 2008 12:58:06 +0200 From: Adrian Moisey User-Agent: Thunderbird 2.0.0.6 (X11/20071022) MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: strange pauses References: <478DDF83.8070106@careerjunction.co.za> <478DE16F.50308@archonet.com> In-Reply-To: <478DE16F.50308@archonet.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/143 X-Sequence-Number: 28382 Hi >> If I tail the logs, I see a steady stream of functions that took >> longer then 5 seconds. But every now and then I see nothing for 3 >> minutes and after that a whole bunch (about 20 - 30) queries all >> finishing at the same second. > > Search this list for references to "checkpoints". If you run > vmstat/iostat for a bit you should see bursts of disk activity at those > times. > > Counter-intuitively you probably want *more* checkpoints (with less data > to write out each time), but see the list archives for discussion. Also > check the manuals for some background info. We use a lot of checkpoints in our database, we don't care about these much. We think this is causing the checkpoint to write a lot of data at checkpoint time. Can we stop this behavior ? -- Adrian Moisey System Administrator | CareerJunction | Your Future Starts Here. Web: www.careerjunction.co.za | Email: adrian@careerjunction.co.za Phone: +27 21 686 6820 | Mobile: +27 82 858 7830 | Fax: +27 21 686 6842