X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id EF7CE52C9F for ; Tue, 2 Aug 2005 13:19:47 -0300 (ADT) 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 44138-01 for ; Tue, 2 Aug 2005 16:19:45 +0000 (GMT) Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by svr1.postgresql.org (Postfix) with ESMTP id 56F8E529D2 for ; Tue, 2 Aug 2005 13:19:44 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id j72GJUYJ011485; Tue, 2 Aug 2005 12:19:30 -0400 (EDT) To: Tobias Brox Cc: pgsql-performance@postgresql.org Subject: Re: "nice"/low priority Query In-reply-to: <20050802160434.GD9278@tobias.lan> References: <20050802160434.GD9278@tobias.lan> Comments: In-reply-to Tobias Brox message dated "Tue, 02 Aug 2005 18:04:34 +0200" Date: Tue, 02 Aug 2005 12:19:30 -0400 Message-ID: <11484.1122999570@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.006 tagged_above=0 required=5 tests=AWL X-Spam-Level: X-Archive-Number: 200508/21 X-Sequence-Number: 13768 Tobias Brox writes: > Is there any ways to give postgresql a hint that a > particular SQL call should be run at lower priority? Since every db > connection has a pid, I can manually run "renice" to scheduele it by the OS > - but of course I can't do it manually all the time. And it won't help you anyway, because renice only affects CPU priority not I/O scheduling ... which, by your description, is the real problem. I think the only thing that's likely to help much is trying to arrange that the "simple" queries only need to touch pages that are already in memory. Some playing around with shared_buffer sizing might help. Also, if you're not on PG 8.0.*, an update might help. regards, tom lane