X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 9FD13DBABC for ; Fri, 18 Nov 2005 12:33:59 -0400 (AST) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 55292-09 for ; Fri, 18 Nov 2005 16:33:57 +0000 (GMT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) by svr1.postgresql.org (Postfix) with ESMTP id DCCE0DBAB1 for ; Fri, 18 Nov 2005 12:33:56 -0400 (AST) Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 11:33:43 -0500 X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov 2005 11:33:36 -0500 Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov 2005 11:33:36 -0500 User-Agent: Microsoft-Entourage/11.2.1.051004 Date: Fri, 18 Nov 2005 08:33:35 -0800 Subject: Re: Hardware/OS recommendations for large databases ( From: "Luke Lonergan" To: "Alex Turner" cc: "Dave Cramer" , "Greg Stark" , "Joshua Marsh" , pgsql-performance@postgresql.org Message-ID: Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( Thread-Index: AcXsXdILENDsmFhREdqKawANk63kWA== In-Reply-To: <33c6269f0511180828m3bc7f41dp186b4573792bf6a0@mail.gmail.com> MIME-Version: 1.0 X-OriginalArrivalTime: 18 Nov 2005 16:33:36.0640 (UTC) FILETIME=[D3059800:01C5EC5D] X-WSS-ID: 6F60DDC721G13536843-05-01 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, RCVD_NUMERIC_HELO=1.253] X-Spam-Score: 1.253 X-Spam-Level: * X-Archive-Number: 200511/362 X-Sequence-Number: 15619 Alex, On 11/18/05 8:28 AM, "Alex Turner" wrote: > Ok - so I ran the same test on my system and get a total speed of 113MB/sec. > Why is this? Why is the system so limited to around just 110MB/sec? I > tuned read ahead up a bit, and my results improve a bit.. OK! Now we're on the same page. Finally someone who actually tests! Check the CPU usage while it's doing the scan. Know what it's doing? Memory copies. We've profiled it extensively. So - that's the suckage - throwing more CPU power helps a bit, but the underlying issue is poorly optimized code in the Postgres executor and lack of I/O asynchrony. - Luke