Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 3130664FC1D for ; Sat, 27 Sep 2008 04:04:27 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 03620-07 for ; Sat, 27 Sep 2008 04:04:16 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by postgresql.org (Postfix) with ESMTP id 7D41964FC00 for ; Sat, 27 Sep 2008 04:04:14 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m8R748Sc001267; Sat, 27 Sep 2008 03:04:08 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m8R7489b001263; Sat, 27 Sep 2008 03:04:08 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Sat, 27 Sep 2008 03:04:08 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: John Huttley cc: pgsql-performance@postgresql.org Subject: Re: Slow updates, poor IO In-Reply-To: <48DD6BAB.8040302@mib-infotech.co.nz> Message-ID: References: <48DBE587.3050406@mib-infotech.co.nz> <48DD6BAB.8040302@mib-infotech.co.nz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200809/238 X-Sequence-Number: 31551 On Sat, 27 Sep 2008, John Huttley wrote: > I've got 32M shared on a 1G machine and 16 checkpoint segments. > I'll run some tests against 64 segments and see what happens. Increase shared_buffers to 256MB as well. That combination should give you much better performance with the type of update you're doing. Right now the database server has to write the index blocks updated to disk all the time because it has so little working room to store them in. If an index block is updated but there is room to keep it memory, it doesn't have to get written out, which considerably lowers the overhead here. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD