X-Original-To: pgsql-docs-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 36DC48B9EAE for ; Sat, 12 Feb 2005 23:23:30 +0000 (GMT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 28240-05 for ; Sat, 12 Feb 2005 23:23:20 +0000 (GMT) Received: from davinci.ethosmedia.com (server227.ethosmedia.com [209.128.84.227]) by svr1.postgresql.org (Postfix) with ESMTP id 3008F8B9ED8 for ; Sat, 12 Feb 2005 23:23:19 +0000 (GMT) X-EthosMedia-Virus-Scanned: no infections found Received: from [63.195.55.98] (account josh@agliodbs.com HELO spooky) by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 7020302; Sat, 12 Feb 2005 15:25:04 -0800 From: Josh Berkus Organization: Aglio Database Solutions To: Mark Kirkwood Subject: Re: How the planner uses statistics Date: Sat, 12 Feb 2005 15:22:10 -0800 User-Agent: KMail/1.6.2 Cc: pgsql-docs@postgresql.org References: <42082E1C.8090408@coretech.co.nz> <420A7E23.1090503@coretech.co.nz> In-Reply-To: <420A7E23.1090503@coretech.co.nz> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <200502121522.10112.josh@agliodbs.com> X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.012 tagged_above=0 required=5 tests=AWL X-Spam-Level: X-Archive-Number: 200502/32 X-Sequence-Number: 2865 Mark, > > I wanted to understand how the planner 'knows' how many rows are likely > > to be emitted in a given stage of a query, and wrote down some examples > > for my own benefit - I then wondered if this would be a good addition to > > the 'Performance Tips' chapter. So... err here it is. > > > > Comments welcome. Terrific. I'd be happy to post this at www.powerpostgresql.org, if you want; I think a lot of people would be interested. -- Josh Berkus Aglio Database Solutions San Francisco