Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 79CD29F9F47 for ; Thu, 14 Dec 2006 11:00:40 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-new, port 10024) with ESMTP id 96284-06 for ; Thu, 14 Dec 2006 11:00:14 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from westnet.com (westnet.com [216.187.52.2]) by postgresql.org (Postfix) with ESMTP id CAA909F9F46 for ; Thu, 14 Dec 2006 11:00:14 -0400 (AST) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.13.8/8.13.8) with ESMTP id kBEF0EBQ015327 for ; Thu, 14 Dec 2006 10:00:14 -0500 (EST) Received: from localhost (gsmith@localhost) by westnet.com (8.13.8/8.13.2/Submit) with ESMTP id kBEF0E8c015323 for ; Thu, 14 Dec 2006 10:00:14 -0500 (EST) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Thu, 14 Dec 2006 10:00:14 -0500 (EST) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Postgresql Performance list Subject: Re: New to PostgreSQL, performance considerations In-Reply-To: Message-ID: References: <457EA39E.1020207@streppone.it> <20061212124803.GA29167@mathom.us> <4580264F.8030109@streppone.it> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200612/365 X-Sequence-Number: 22421 On Wed, 13 Dec 2006, Ron wrote: > The slowest results, Michael's, are on the system with what appears to be the > slowest CPU of the bunch; and the ranking of the rest of the results seem to > similarly depend on relative CPU performance. This is not what one would > naively expect when benching a IO intensive app like a DBMS. pgbench with 3000 total transactions and fsync off is barely doing I/O to disk; it's writing a bunch of data to the filesystem cache and ending the benchmark before the data even makes it to the hard drive. This is why his results become completely different as soon as the number of transactions increases. With little or no actual disk writes, you should expect results to be ranked by CPU speed. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD