Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 86F8D2E3B6F for ; Thu, 13 Dec 2007 12:40:01 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 28742-07 for ; Thu, 13 Dec 2007 12:39:49 -0400 (AST) Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) by postgresql.org (Postfix) with ESMTP id A50432E3127 for ; Thu, 13 Dec 2007 12:39:55 -0400 (AST) Received: from Courts-MTA by gwmta.wicourts.gov with Novell_GroupWise; Thu, 13 Dec 2007 10:39:54 -0600 Message-Id: <47610BF3.EE98.0025.0@wicourts.gov> X-Mailer: Novell GroupWise Internet Agent 7.0.2 Date: Thu, 13 Dec 2007 10:39:47 -0600 From: "Kevin Grittner" To: "Tom Lane" Cc: "Simon Riggs" , Subject: Re: Heavy write activity on first vacuum of fresh TOAST data References: <4760FF69.EE98.0025.0@wicourts.gov> <1197562283.4255.1829.camel@ebony.site> <476108F2.EE98.0025.0@wicourts.gov><476108F2.EE98.0025.0@wicourts.gov> <13267.1197563721@sss.pgh.pa.us> In-Reply-To: <13267.1197563721@sss.pgh.pa.us> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200712/189 X-Sequence-Number: 28005 >>> On Thu, Dec 13, 2007 at 10:35 AM, in message <13267.1197563721@sss.pgh.= pa.us>, Tom Lane wrote:=20 > "Kevin Grittner" writes: >> ... although to a naive user it's not clear what >> is known at vacuum time that the INSERT into the empty table >> couldn't have inferred. >=20 > The fact that the INSERT actually committed. =20 Fair enough. I suppose that the possibility that of access before the commit would preclude any optimization that would assume the commit is more likely than a rollback, and do the extra work only in the unusual case? =20 -Kevin =20