Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 614CF633A49 for ; Thu, 2 Apr 2009 16:31:09 -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 68232-06 for ; Thu, 2 Apr 2009 16:31:03 -0300 (ADT) Received: from mx1.hub.org (mx1.hub.org [200.46.208.106]) by mail.postgresql.org (Postfix) with ESMTP id 277FB6332C9 for ; Thu, 2 Apr 2009 16:31:04 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail128169.authsmtp.net (outmail128169.authsmtp.net [62.13.128.169]) by mx1.hub.org (Postfix) with ESMTP id 328E41259D38 for ; Thu, 2 Apr 2009 16:29:23 -0300 (ADT) Received: from mail-c193.authsmtp.com (mail-c193.authsmtp.com [62.13.128.118]) by punt10.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id n32JTGQR025179; Thu, 2 Apr 2009 20:29:16 +0100 (BST) Received: from [192.168.0.4] (85-211-223-92.dyn.gotadsl.co.uk [85.211.223.92]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id n32JTEEo077890; Thu, 2 Apr 2009 20:29:15 +0100 (BST) Subject: Re: [COMMITTERS] pgsql: If we expect a hash join to be performed in multiple batches, From: Simon Riggs To: Tom Lane Cc: pgsql-hackers@postgresql.org In-Reply-To: <20090326171535.6B9BF754ADE@cvs.postgresql.org> References: <20090326171535.6B9BF754ADE@cvs.postgresql.org> Content-Type: text/plain Date: Thu, 02 Apr 2009 18:11:23 +0100 Message-Id: <1238692283.5444.123.camel@ebony.2ndQuadrant> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit X-Server-Quench: 8d6d1b2e-1fbc-11de-8a51-002264978518 X-AuthRoute: OCdxZQATClZOTQEd DAteCiNZVAwpPBRK HVkIKg5MJUcNSQVJ NksadBtFaAdbbElD HGQLW11EUl17W2p/ ag8fZQBDYEtPQQdo U1ZAQE1QEQdtHhxP WB0cKH0HAlpGf3l4 bEYsX3BdVQpyIUAp QxxWQHAHMzUzdWEe BBVFf1JRcR5Kfh1H bFR2U3sIYG1JBC9q VzwYGBUUHAljBR5u d0kVIkkLRRRDPzB0 WB1KECU3EEYZDyx7 LxU9KhYeG0cXelk1 eVEsEUoVKREVEAhT EyMsASkRIkQFWysz CQ4SV0cCGz1QWmM0 X-Authentic-SMTP: 61633235383639.pelican.dmpriest.net.uk:1378/Kp X-Report-SPAM: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-Virus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200904/135 X-Sequence-Number: 136238 On Thu, 2009-03-26 at 17:15 +0000, Tom Lane wrote: > Log Message: > ----------- > If we expect a hash join to be performed in multiple batches, suppress > "physical tlist" optimization on the outer relation (ie, force a projection > step to occur in its scan). This avoids storing useless column values when > the outer relation's tuples are written to temporary batch files. Can we add "batches=N" to the EXPLAIN output for Hash and/or Hash Join? -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support