Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 8BB706502CB for ; Thu, 28 Aug 2008 23:29:54 -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 82157-02 for ; Thu, 28 Aug 2008 23:29:44 -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 7B3A06502C8 for ; Thu, 28 Aug 2008 23:29:50 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m7T2Tkuf016234; Thu, 28 Aug 2008 22:29:46 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m7T2TjWC016230; Thu, 28 Aug 2008 22:29:46 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Thu, 28 Aug 2008 22:29:45 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: =?ISO-8859-1?Q?Andr=E9_Volpato?= cc: pgsql-performance@postgresql.org Subject: Re: Postgres not using array In-Reply-To: <48AD735D.6040403@ecomtecnologia.com.br> Message-ID: References: <48AC8292.5000708@ecomtecnologia.com.br> <48AD735D.6040403@ecomtecnologia.com.br> MIME-Version: 1.0 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: Content-Type: TEXT/PLAIN; CHARSET=X-UNKNOWN; FORMAT=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Content-ID: X-Archive-Number: 200808/406 X-Sequence-Number: 31287 On Thu, 21 Aug 2008, Andr=E9 Volpato wrote: > So, what is slowing down is the CPU (Intel(R) Pentium(R) Dual CPU E2160= =20 > @ 1.80GHz)..In practice, I have noticed that dual 1.8 is worse than=20 > single 3.0. We have another server wich is a Pentium D 3.0 GHz, that=20 > runs faster. Pentium D models are all dual-core so either you've got the wrong model=20 number here or you've actually comparing against a 2X3.0GHz part. The Core 2 Duo E2160 has a very small CPU cache--512KB per core. Your=20 older Pentium system probably has quite a bit more. I suspect that's the= =20 main reason it runs faster on this application. > I am a bit confused about what CPU is best for Postgres. Our apps is=20 > mostly read, with a few connections and heavy queryes. There are a lot of things you can run into with Postgres that end up being= =20 limited by the fact that they only run on a single core, as you've seen=20 here. If you've only got a fairly small number of connections running CPU= =20 heavy queries, you probably want a processor with lots of L2 cache and a=20 fast clock speed, rather than adding a large number of cores running at a= =20 slower speed. The very small L2 cache on your E2160 is likely what's=20 holding it back here, and even though the newer processors are=20 significantly more efficient per clock the gap between 1.8GHz and 3.0GHz=20 is pretty big. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD=