Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 98667B60DE6 for ; Wed, 1 Jun 2011 18:53:25 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 19727-10 for ; Wed, 1 Jun 2011 21:53:18 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from cooker.cnx.rice.edu (cooker.cnx.rice.edu [168.7.5.70]) by mail.postgresql.org (Postfix) with ESMTP id 44C15B60A68 for ; Wed, 1 Jun 2011 18:53:16 -0300 (ADT) Received: from reedstrm by cooker.cnx.rice.edu with local (Exim 4.72) (envelope-from ) id 1QRtLn-0007Jj-CB for pgsql-hackers@postgresql.org; Wed, 01 Jun 2011 16:53:15 -0500 Date: Wed, 1 Jun 2011 16:53:15 -0500 From: "Ross J. Reedstrom" To: pgsql-hackers@postgresql.org Subject: Re: [PERFORM] Hash Anti Join performance degradation Message-ID: <20110601215315.GC14215@rice.edu> References: <7913.1306900062@sss.pgh.pa.us> <24247.1306959956@sss.pgh.pa.us> <24461.1306960516@sss.pgh.pa.us> <24707.1306961256@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201106/63 X-Sequence-Number: 188776 On Wed, Jun 01, 2011 at 04:58:36PM -0400, Robert Haas wrote: > On Wed, Jun 1, 2011 at 4:47 PM, Tom Lane wrote: > > Robert Haas writes: > >> I guess the real issue here is that m1.id < m2.id has to be evaluated > >> as a filter condition rather than a join qual. > > > > Well, if you can invent an optimized join technique that works for > > inequalities, go for it ... but I think you should get at least a > > PhD thesis out of that. > > Sounds good, except that so far NOT getting a PhD seems like a much > better financial prospect. :-) Yeah, last time I heard of some Uni being so impressed by independent work that they just sort of handed out a Ph.D. it involved a Swiss patent clerk ... Ross -- Ross Reedstrom, Ph.D. reedstrm@rice.edu Systems Engineer & Admin, Research Scientist phone: 713-348-6166 Connexions http://cnx.org fax: 713-348-3665 Rice University MS-375, Houston, TX 77005 GPG Key fingerprint = F023 82C8 9B0E 2CC6 0D8E F888 D3AE 810E 88F0 BEDE