Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id EB98E6326A5 for ; Fri, 17 Apr 2009 12:02:38 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.208.211]) (amavisd-maia, port 10024) with ESMTP id 12200-05 for ; Fri, 17 Apr 2009 12:02:37 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id 88FEC632582 for ; Fri, 17 Apr 2009 12:02:36 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id n3HF2YJX021239; Fri, 17 Apr 2009 11:02:34 -0400 (EDT) To: Kris Jurka cc: pgsql-performance@postgresql.org Subject: Re: No hash join across partitioned tables? In-reply-to: References: <7163.1239923531@sss.pgh.pa.us> Comments: In-reply-to Kris Jurka message dated "Thu, 16 Apr 2009 21:02:04 -0400" Date: Fri, 17 Apr 2009 11:02:34 -0400 Message-ID: <21238.1239980554@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.362 tagged_above=0 required=5 tests=AWL=-0.048, SUBJECT_FUZZY_TION=0.41 X-Spam-Level: X-Archive-Number: 200904/286 X-Sequence-Number: 33653 Kris Jurka writes: > So the default disable_cost isn't enough to push it to use the hash join > plan and goes back to nestloop. Since disable_cost hasn't been touched > since January 2000, perhaps it's time to bump that up to match today's > hardware and problem sizes? I think disable_cost was originally set at a time when costs were integers :-(. Yeah, there's probably no reason not to throw another zero or two on it. Is there another issue here besides that one? I think you were hoping that the hash join would be faster than the alternatives, but the cost estimate says it's a lot slower. Is that actually the case? regards, tom lane