Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id C3C939FB620; Wed, 24 Jan 2007 23:57:48 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-new, port 10024) with ESMTP id 50635-02; Wed, 24 Jan 2007 23:57:45 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from noel.decibel.org (noel.decibel.org [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id B67B99FB2E6; Wed, 24 Jan 2007 23:57:45 -0400 (AST) Received: by noel.decibel.org (Postfix, from userid 1001) id 660315647C; Wed, 24 Jan 2007 21:57:44 -0600 (CST) Received: (hashcash-sendmail, from uid 1001); Wed, 24 Jan 2007 21:57:42 -0600 Date: Wed, 24 Jan 2007 21:57:42 -0600 From: "Jim C. Nasby" To: Galy Lee , pgsql-performance@postgresql.org, Hackers Subject: Re: [HACKERS] how to plan for vacuum? Message-ID: <20070125035741.GE64372@nasby.net> References: <45B6F0A8.1050705@oss.ntt.co.jp> <20070125033917.GD64372@nasby.net> <20070125035202.GI26006@alvh.no-ip.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070125035202.GI26006@alvh.no-ip.org> X-Operating-System: FreeBSD 6.1-RELEASE-p10 amd64 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.13 (2006-08-11) X-Hashcash: 1:20:070125:lee.galy@oss.ntt.co.jp::/CbiWXGaAOAP1g0B:000000000000000 0000000000000000000000000rF5 X-Hashcash: 1:20:070125:pgsql-performance@postgresql.org::WuabtKuvBibZXptR:00000 0000000000000000000000002Yh5 X-Hashcash: 1:20:070125:pgsql-hackers@postgresql.org::3pIpVe5f6l5pRYs+:000000000 0000000000000000000000000LJy X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200701/367 X-Sequence-Number: 22968 On Thu, Jan 25, 2007 at 12:52:02AM -0300, Alvaro Herrera wrote: > Jim C. Nasby wrote: > > > I'll generally start with a cost delay of 20ms and adjust based on IO > > utilization. > > I've been considering set a default autovacuum cost delay to 10ms; does > this sound reasonable? For a lightly loaded system, sure. For a heavier load that might be too much, but of course that's very dependent on not only your hardware, but how much you want vacuum to interfere with normal operations. Though, I'd say as a default it's probably better to be more aggressive rather than less. Also, it might be better to only set autovac_cost_delay by default; presumably if someone's running vacuum by hand they want it done pronto. -- Jim Nasby jim@nasby.net EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)