Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 65BF26501D0 for ; Mon, 1 Sep 2008 03:44:14 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 46941-03-4 for ; Mon, 1 Sep 2008 03:43:57 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from ey-out-2122.google.com (ey-out-2122.google.com [74.125.78.24]) by postgresql.org (Postfix) with ESMTP id 5DAF3650331 for ; Mon, 1 Sep 2008 03:29:34 -0300 (ADT) Received: by ey-out-2122.google.com with SMTP id 6so627738eyi.61 for ; Sun, 31 Aug 2008 23:29:33 -0700 (PDT) Received: by 10.210.89.4 with SMTP id m4mr6026399ebb.21.1220250572804; Sun, 31 Aug 2008 23:29:32 -0700 (PDT) Received: from ?80.222.42.69? ( [80.222.42.69]) by mx.google.com with ESMTPS id 33sm4541043nfu.7.2008.08.31.23.29.31 (version=TLSv1/SSLv3 cipher=RC4-MD5); Sun, 31 Aug 2008 23:29:32 -0700 (PDT) Message-ID: <48BB8BC9.7080508@enterprisedb.com> Date: Mon, 01 Sep 2008 09:29:29 +0300 Organization: EnterpriseDB User-Agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509) MIME-Version: 1.0 To: Abhijit Menon-Sen CC: PostgreSQL-development Subject: Re: [PATCHES] VACUUM Improvements - WIP Patch References: <2e78013d0807132050j16cdc558s4dc3f889371a937d@mail.gmail.com> <200808230336.m7N3aOc15945@momjian.us> <48B1831F.7010002@commandprompt.com> <48B1AB17.9010905@zeut.net> <25792.1219605368@sss.pgh.pa.us> <48B21989.9090200@zeut.net> <1683.1219631879@sss.pgh.pa.us> <48B25E11.5080803@enterprisedb.com> <20080901004646.GA24702@toroid.org> In-Reply-To: <20080901004646.GA24702@toroid.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit From: Heikki Linnakangas 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: 200809/4 X-Sequence-Number: 123133 Abhijit Menon-Sen wrote: > At 2008-08-25 10:24:01 +0300, heikki@enterprisedb.com wrote: >> My original plan was to enable index-only-scans using the DSM as well >> for 8.4, but it's pretty clear at this point that I don't have the >> time to finish that :-(. > > I wonder how hard that would be. It's doable, for sure. The pieces I see as required for that are: 1. change the indexam API so that indexes can return tuples 2. make sure the DSM is suitable for index-only-scans. Ie. it must be completely up-to-date and WAL-logged, so that if the DSM says that all tuples on a page are visible, they really must be. 3. planner/stats changes, so that the planner can estimate how much of an index scan can be satisfied without looking at the heap (it's not an all-or-nothing plan-time decision with this design) -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com