Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id 4EF329FB3BB; Fri, 13 Oct 2006 13:47:17 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 14464-08; Fri, 13 Oct 2006 13:47:08 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from localhost.localdomain (stark.xeocode.com [216.58.44.227]) by postgresql.org (Postfix) with ESMTP id DE89A9FA27F; Fri, 13 Oct 2006 13:47:07 -0300 (ADT) Received: from localhost ([127.0.0.1] helo=localhost.localdomain) by localhost.localdomain with esmtp (Exim 4.62) (envelope-from ) id 1GYQBK-0002uj-1p; Fri, 13 Oct 2006 12:46:46 -0400 From: Gregory Stark To: josh@agliodbs.com Cc: "Jim C. Nasby" , pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org Subject: Re: [HACKERS] Hints proposal In-Reply-To: <200610121358.22739.josh@agliodbs.com> (Josh Berkus's message of "Thu, 12 Oct 2006 13:58:22 -0700") Organization: EnterpriseDB References: <20061012151439.GT28647@nasby.net> <452E6FFE.7010504@agliodbs.com> <20061012192410.GU28647@nasby.net> <200610121358.22739.josh@agliodbs.com> X-Draft-From: ("nnimap+webmail.enterprisedb.com:Inbox" 5259) Date: Fri, 13 Oct 2006 12:46:45 -0400 Message-ID: <87odsg17uy.fsf@enterprisedb.com> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.263 tagged_above=0 required=5 tests=AWL, FORGED_RCVD_HELO X-Spam-Level: X-Archive-Number: 200610/442 X-Sequence-Number: 21571 Josh Berkus writes: >> > I actually think the way to attack this issue is to discuss the kinds >> > of errors the planner makes, and what tweaks we could do to correct >> > them. Here's the ones I'm aware of: >> > >> > -- Incorrect selectivity of WHERE clause >> > -- Incorrect selectivity of JOIN >> > -- Wrong estimate of rows returned from SRF >> > -- Incorrect cost estimate for index use >> > >> > Can you think of any others? -- Incorrect estimate for result of DISTINCT or GROUP BY. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com