Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 4D4B063238A for ; Wed, 14 Jan 2009 21:18:45 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 64209-01 for ; Wed, 14 Jan 2009 21:18:38 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from alexis.jtlnet.com (alexis.jtlnet.com [69.36.9.81]) by mail.postgresql.org (Postfix) with ESMTP id E933863238D for ; Wed, 14 Jan 2009 21:18:38 -0400 (AST) Received: from [192.168.10.103] (cpe-065-190-223-140.nc.res.rr.com [::ffff:65.190.223.140]) (TLS: TLSv1/SSLv3,256bits,AES256-SHA) by alexis.jtlnet.com with esmtp; Wed, 14 Jan 2009 20:15:23 -0500 id 0008490A.496E8E2C.0000394F Message-ID: <496E8EEA.8050206@dunslane.net> Date: Wed, 14 Jan 2009 20:18:34 -0500 From: Andrew Dunstan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.0.12) Gecko/20071019 Fedora/1.0.9-3.fc6 pango-text SeaMonkey/1.0.9 MIME-Version: 1.0 To: Bruce Momjian CC: Gregory Stark , Heikki Linnakangas , PostgreSQL-development , Tom Lane Subject: Re: Visibility map, partial vacuums References: <200901150055.n0F0tLK27057@momjian.us> In-Reply-To: <200901150055.n0F0tLK27057@momjian.us> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200901/1107 X-Sequence-Number: 131751 Bruce Momjian wrote: > Would someone tell me why 'autovacuum_freeze_max_age' defaults to 200M > when our wraparound limit is around 2B? > Presumably because of this (from the docs): "The commit status uses two bits per transaction, so if autovacuum_freeze_max_age has its maximum allowed value of a little less than two billion, pg_clog can be expected to grow to about half a gigabyte." cheers andrew