Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 629A09FB502 for ; Fri, 28 Sep 2007 17:56:59 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 14651-07 for ; Fri, 28 Sep 2007 17:56:50 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 089FE9FB500 for ; Fri, 28 Sep 2007 17:56:52 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id l8SKunaY019038; Fri, 28 Sep 2007 16:56:49 -0400 (EDT) To: Arctic Toucan cc: pgsql-performance@postgresql.org Subject: Re: OOM Errors as a result of table inheritance and a bad plan(?) In-reply-to: References: Comments: In-reply-to Arctic Toucan message dated "Fri, 28 Sep 2007 13:50:32 -0400" Date: Fri, 28 Sep 2007 16:56:49 -0400 Message-ID: <19037.1191013009@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200709/475 X-Sequence-Number: 27020 Arctic Toucan writes: > -- Is there something magical about the hash aggregate estimate of 200 rows? Yeah, it's the default :-( > Is this a bug, or some subtlety of the Postgres query planner? It's an, um, known deficiency --- the planner hasn't got any idea how to construct aggregated statistics for an inheritance tree. regards, tom lane