X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 7A02F9DCDE7 for ; Wed, 1 Feb 2006 16:41:10 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 27990-08 for ; Wed, 1 Feb 2006 16:41:11 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 124D79DCC07 for ; Wed, 1 Feb 2006 16:41:07 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id k11Kf9uM004388; Wed, 1 Feb 2006 15:41:09 -0500 (EST) To: Ralph Mason cc: pgsql-performance@postgresql.org Subject: Re: Index Usage using IN In-reply-to: <1138825370.8376.5.camel@toonses.gghcwest.com> References: <43E1164B.7020104@telogis.com> <1138825370.8376.5.camel@toonses.gghcwest.com> Comments: In-reply-to "Jeffrey W. Baker" message dated "Wed, 01 Feb 2006 12:22:50 -0800" Date: Wed, 01 Feb 2006 15:41:09 -0500 Message-ID: <4387.1138826469@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.103 required=5 tests=[AWL=0.103] X-Spam-Score: 0.103 X-Spam-Level: X-Archive-Number: 200602/28 X-Sequence-Number: 17014 "Jeffrey W. Baker" writes: > On Thu, 2006-02-02 at 09:12 +1300, Ralph Mason wrote: >> Select ID from TableA where ID not IN ( Select ID from Table B) > Have you considered this: > SELECT ID from TableA EXCEPT Select ID from Table B Also, increasing work_mem might persuade the planner to try a hashed subplan, which'd be a lot better than what you have. Note that it's quite unlikely that indexes are going to help for this. regards, tom lane