Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 1344D9F9724 for ; Fri, 31 Aug 2007 16:08:56 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 98918-02 for ; Fri, 31 Aug 2007 16:08:47 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 5CC5D9F9786 for ; Fri, 31 Aug 2007 16:08:49 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id l7VJ8j5b000248; Fri, 31 Aug 2007 15:08:45 -0400 (EDT) To: Alvaro Herrera cc: Mikko Partio , Pallav Kalva , pgsql-performance@postgresql.org Subject: Re: 8.2 Autovacuum BUG ? In-reply-to: <20070831184744.GK8046@alvh.no-ip.org> References: <46D83427.60001@livedatagroup.com> <25038.1188574775@sss.pgh.pa.us> <46D83C50.3040409@livedatagroup.com> <20070831161158.GD8046@alvh.no-ip.org> <2ca799770708311131r5ae5e3eera66a7cea1fc5917d@mail.gmail.com> <20070831184744.GK8046@alvh.no-ip.org> Comments: In-reply-to Alvaro Herrera message dated "Fri, 31 Aug 2007 14:47:44 -0400" Date: Fri, 31 Aug 2007 15:08:45 -0400 Message-ID: <247.1188587325@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/407 X-Sequence-Number: 26537 Alvaro Herrera writes: > Mikko Partio escribió: >> Off-topic question: the documentation says that XID numbers are 32 bit. >> Could the XID be 64 bit when running on a 64 bit platform? That would >> effectively prevent wrap-around issues. > No, because they would take too much space in tuple headers. It's worth noting that the patch Florian is working on, to suppress assignment of XIDs for transactions that never write anything, will make for a large reduction in the rate of XID consumption in many real-world applications. That will reduce the need for tuple freezing and probably lessen the attraction of wider XIDs even more. If he gets it done soon (before the HOT dust settles) I will be strongly tempted to try to sneak it into 8.3 ... regards, tom lane