Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 6AE582E3732 for ; Thu, 17 Jan 2008 09:44:35 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 42383-09 for ; Thu, 17 Jan 2008 09:44:30 -0400 (AST) Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.183]) by postgresql.org (Postfix) with ESMTP id 0058B2E3555 for ; Thu, 17 Jan 2008 09:44:29 -0400 (AST) Received: by wa-out-1112.google.com with SMTP id m38so1181730waf.5 for ; Thu, 17 Jan 2008 05:44:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=jMMWO01rhb0bhqnwRrCIYlcvjXg0K7076KX3C3eXVJc=; b=kS2S0uAi3MmRC4RBhhKmhpFBcCvPp4RQov8E+YThCANH/Q+oy6/3Ew6TZK25FaxGd7ujoqDQtlbSxyax+VA0JOnbgGvDrpYKfehIMrkRcCle9/pkOzdC4U9fGltzvJcUBaqWFdtCrCDvt4n2/0k4tm8Wwm9sULCWXlTYwbtlVKc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=tlh3Co+kaMLry0FnCjbH0PoXd5e1QL1AidHlhW/gT14MFHiIRDeG9qEtDWxH3Gcjntj7ERXHyqIbB2yhOygxoecETHCAXxe2pa3hlSZp6Pz2djWxuWh13Z61yUtJ+vJ2iezbbOf2pqdocpjPgCPrU6jtd84Hrb3W36GS1/O42P4= Received: by 10.114.178.1 with SMTP id a1mr2401359waf.135.1200577468310; Thu, 17 Jan 2008 05:44:28 -0800 (PST) Received: by 10.114.133.5 with HTTP; Thu, 17 Jan 2008 05:44:28 -0800 (PST) Message-ID: Date: Thu, 17 Jan 2008 07:44:28 -0600 From: "Scott Marlowe" To: "Adrian Moisey" Subject: Re: strange pauses Cc: "Greg Smith" , pgsql-performance@postgresql.org In-Reply-To: <478EFAB0.30205@careerjunction.co.za> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <478DDF83.8070106@careerjunction.co.za> <478DE16F.50308@archonet.com> <478EFAB0.30205@careerjunction.co.za> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/138 X-Sequence-Number: 28377 On Jan 17, 2008 12:50 AM, Adrian Moisey wrote: > Hi > > >> 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. > > > > The most straightforward way to prove or disprove that the slow queries > > line up with checkpoints is to set to checkpoint_warning to a high value > > (3600 should work), which should log every checkpoint, and then see if > > they show up at the same time in the logs. > > You guys were spot on. During these pauses the IO goes up high. You need to tune your background writer process. See this link: http://www.westnet.com/~gsmith/content/postgresql/chkp-bgw-83.htm