X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 6C6F19DCADF for ; Tue, 29 Nov 2005 11:01:29 -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 32454-10 for ; Tue, 29 Nov 2005 11:01:32 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com [69.145.82.195]) by postgresql.org (Postfix) with ESMTP id D8F6B9DCA9F for ; Tue, 29 Nov 2005 11:01:25 -0400 (AST) Received: from [69.145.82.253] (unknown [69.145.82.253]) by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id 4B39411027B for ; Tue, 29 Nov 2005 07:01:29 -0800 (PST) Message-ID: <438C6D4A.4000103@boreham.org> Date: Tue, 29 Nov 2005 08:01:30 -0700 From: David Boreham User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 To: pgsql-hackers@postgresql.org Subject: Re: ice-broker scan thread References: <6418CC03D0FB1943A464E1FEFB3ED46B01B220E7@im01.cincom.com> In-Reply-To: <6418CC03D0FB1943A464E1FEFB3ED46B01B220E7@im01.cincom.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200511/1474 X-Sequence-Number: 76756 >threw up some threads to read ahead, then my user thread and my read >ahead threads would thrash on trying to lock the buffer slots. So, I >had the read ahead threads start at some distance into the table, and >work toward the beginning. The user thread would do its own I/O until > > Ah. The lightbulb went on. You want multiple outstanding I/O operations in the case that table or index spans multiple physical disks.