Received: from localhost (unknown [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id 682DC2E4875 for ; Fri, 14 Dec 2007 12:32:52 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-maia, port 10024) with ESMTP id 70759-01-6 for ; Fri, 14 Dec 2007 12:32:49 -0400 (AST) Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 54E572E446E for ; Fri, 14 Dec 2007 12:22:52 -0400 (AST) 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 lBEGMn0p008117; Fri, 14 Dec 2007 11:22:49 -0500 (EST) To: Matthew cc: pgsql-performance@postgresql.org Subject: Re: Heavy write activity on first vacuum of fresh TOASTa In-reply-to: References: <4760FF69.EE98.0025.0@wicourts.gov> <1197562283.4255.1829.camel@ebony.site> Comments: In-reply-to Matthew message dated "Fri, 14 Dec 2007 15:42:33 +0000" Date: Fri, 14 Dec 2007 11:22:49 -0500 Message-ID: <8116.1197649369@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200712/217 X-Sequence-Number: 28033 Matthew writes: > Interesting thread. Now, I know absolutely nothing about how the data is > stored, but it strikes me as being non-optimal that every single block on > the disc needs to be written again just to update some hint bits. Could > those bits be taken out into a separate bitmap stored somewhere else? You are trying to optimize the wrong thing. Making vacuum cheaper at the cost of making every tuple lookup more expensive is not going to be a win. regards, tom lane