Received: from localhost (unknown [200.46.204.183]) by developer.postgresql.org (Postfix) with ESMTP id 2233A2E0059 for ; Thu, 15 May 2008 00:07:55 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 47276-09 for ; Thu, 15 May 2008 00:07:43 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by developer.postgresql.org (Postfix) with ESMTP id 654CC2E0047 for ; Thu, 15 May 2008 00:03:40 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m4F33c30012800; Wed, 14 May 2008 23:03:38 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m4F33boZ012791; Wed, 14 May 2008 23:03:37 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Wed, 14 May 2008 23:03:37 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Pavan Deolasee cc: Alvaro Herrera , pgsql-performance@postgresql.org Subject: Re: I/O on select count(*) In-Reply-To: <2e78013d0805141940x50c3f51u439019e8e592959@mail.gmail.com> Message-ID: References: <920841.71690.qm@web44808.mail.sp1.yahoo.com> <482B1D5F.EE98.0025.0@wicourts.gov> <20080515020553.GN9838@alvh.no-ip.org> <2e78013d0805141940x50c3f51u439019e8e592959@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200805/195 X-Sequence-Number: 30163 On Thu, 15 May 2008, Pavan Deolasee wrote: > I had suggested in the past that whenever we set hint bits for a tuple, > we should check all other tuples in the page and set their hint bits too > to avoid multiple writes of the same page. I guess the idea got rejected > because of lack of benchmarks to prove the benefit.