X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 04E609DC82A for ; Tue, 31 Jan 2006 13:01:01 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 01200-04 for ; Tue, 31 Jan 2006 13:00:59 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) by postgresql.org (Postfix) with ESMTP id EA0329DC800 for ; Tue, 31 Jan 2006 13:00:53 -0400 (AST) Received: from 172.16.1.25 by mail.Mi8.com with ESMTP (- Welcome to Mi8 Corporation www.Mi8.com (D1)); Tue, 31 Jan 2006 12:00:46 -0500 X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by D01HOST03.Mi8.com with Microsoft SMTPSVC(6.0.3790.1830); Tue, 31 Jan 2006 12:00:36 -0500 Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Tue, 31 Jan 2006 17:00:31 +0000 User-Agent: Microsoft-Entourage/11.2.1.051004 Date: Tue, 31 Jan 2006 09:00:30 -0800 Subject: Re: Huge Data sets, simple queries From: "Luke Lonergan" To: "Jim C. Nasby" cc: "Mike Biamonte" , pgsql-performance@postgresql.org Message-ID: Thread-Topic: [PERFORM] Huge Data sets, simple queries Thread-Index: AcYmh9c6Fdnw4JJ7EdqBvAANk63kWA== In-Reply-To: <20060130202524.GB3920@pervasive.com> MIME-Version: 1.0 X-OriginalArrivalTime: 31 Jan 2006 17:00:36.0683 (UTC) FILETIME=[DB3609B0:01C62687] X-WSS-ID: 6FC1483732K1571066-04-01 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=1.3 required=5 tests=[AWL=0.047, RCVD_NUMERIC_HELO=1.253] X-Spam-Score: 1.3 X-Spam-Level: * X-Archive-Number: 200601/488 X-Sequence-Number: 16966 Jim, On 1/30/06 12:25 PM, "Jim C. Nasby" wrote: > Why divide by 2? A good raid controller should be able to send read > requests to both drives out of the mirrored set to fully utilize the > bandwidth. Of course, that probably won't come into play unless the OS > decides that it's going to read-ahead fairly large chunks of the table > at a time... I've not seen one that does, nor would it work in the general case IMO. In RAID1 writes are duplicated and reads come from one of the copies. You could alternate read service requests to minimize rotational latency, but you can't improve bandwidth. - Luke