Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id 95BE19FB4EB for ; Thu, 12 Apr 2007 18:52:08 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-maia, port 10024) with ESMTP id 29339-02 for ; Thu, 12 Apr 2007 18:52:05 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from exchange.g2switchworks.com (mail.g2switchworks.com [63.87.162.25]) by postgresql.org (Postfix) with ESMTP id 752F49FB3EA for ; Thu, 12 Apr 2007 18:52:05 -0300 (ADT) Received: from 10.10.1.37 ([10.10.1.37]) by exchange.g2switchworks.com ([10.10.1.2]) with Microsoft Exchange Server HTTP-DAV ; Thu, 12 Apr 2007 21:52:04 +0000 Received: from state.g2switchworks.com by mail.g2switchworks.com; 12 Apr 2007 16:52:04 -0500 Subject: Re: Strangely Variable Query Performance From: Scott Marlowe To: Steve Cc: PostgreSQL Performance In-Reply-To: References: <57271CC2-BCB1-4ACA-A177-4FF64F1BC33F@brandeis.edu> <16E9A17C-ADFA-43B2-B7EA-5C7A4D7E96D1@event-s.net> <0914C05F-BA1B-4A6C-A1B1-52256BC851A4@event-s.net> <1176396964.13754.16.camel@state.g2switchworks.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1176414724.13754.23.camel@state.g2switchworks.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) Date: Thu, 12 Apr 2007 16:52:04 -0500 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200704/264 X-Sequence-Number: 24141 On Thu, 2007-04-12 at 16:03, Steve wrote: > Hey there; > > On a Postgres 8.2.3 server, I've got a query that is running very slow in > some cases. With some work, I've determined the 'slow part' of the query. > :) This is a query on a table with like 10 million rows or something like > that. encounter_id is an integer and receipt is of type 'date'. SNIP > Seq Scan on detail_summary ds (cost=0.00..1902749.83 rows=9962 width=4) > Filter: ((receipt >= '1998-12-30'::date) AND (encounter_id = ANY > ('{8813186,8813187,8813188,8813189,8813190,8813191,8813192,8813193,8813194,8813195,8813196,8813197,8813198,8813199,8813200,8813201,8813202,8813203,8813204,8813205,8813206,8813207,8813208,8813209,8813210,8813211,8813212,8813213,8813214,8813215,8813216,8813217,8813218,8813219,8813220,8813221,8813222,8813223,8813224,8813225,8813226,8813227,8813228,8813229,8813230,8813231,8813232,8813233,8813234,8813235,8813236,8813237,8813238,8813239,8813240,8813241,8813242,8813243,8813244,8813245,8813246,8813247,8813248,8813249,8813250,8813251,8813252,8813253,8813254,8813255,8813256,8813257,8813258,8813259,8813260,8813261,8813262,8813263,8813264,8813265,8813266,8813267,8813268,8813269,8813270,8813271,8813272,8813273,8813274,8813275,8813276,8813277,8813278,8813279,8813280,8813281,8813282,8813283,8813284,8815534}'::integer[]))) > (2 rows) How accurate is the row estimate made by the planner? (explain analyze to be sure)