Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 471A69FB565 for ; Thu, 15 Feb 2007 12:35:08 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-new, port 10024) with ESMTP id 54216-05 for ; Thu, 15 Feb 2007 12:34:51 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id D91DA9FB3AA for ; Thu, 15 Feb 2007 12:34:51 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id l1FGYnbr026634; Thu, 15 Feb 2007 11:34:49 -0500 (EST) To: Alvaro Herrera cc: Guillaume Smet , pgsql-performance@postgresql.org Subject: Re: Question about Bitmap Heap Scan/BitmapAnd In-reply-to: <20070215162733.GO4682@alvh.no-ip.org> References: <1d4e0c10702130832i35484abfmb229f5d0b4d9223b@mail.gmail.com> <1285.1171385353@sss.pgh.pa.us> <1d4e0c10702130917x5b6ddaf7g540bfe1f7c93b728@mail.gmail.com> <1977.1171389065@sss.pgh.pa.us> <1d4e0c10702150805i73097134uf45ce1faa80e3763@mail.gmail.com> <20070215162733.GO4682@alvh.no-ip.org> Comments: In-reply-to Alvaro Herrera message dated "Thu, 15 Feb 2007 13:27:33 -0300" Date: Thu, 15 Feb 2007 11:34:49 -0500 Message-ID: <26633.1171557289@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.05 tagged_above=0 required=5 tests=AWL, BAYES_50, SPF_HELO_PASS, SPF_PASS X-Spam-Level: X-Archive-Number: 200702/174 X-Sequence-Number: 23228 Alvaro Herrera writes: > Guillaume Smet escribió: >> Is it normal I have no recheck cond and the index cond of Bitmap Index >> Scan is in the filter? Is it also a consequence of the code you >> pointed? > It is in the filter, is it not? Having a recheck would be redundant. Yeah, but his question is why is it in the filter? I think that the answer is probably "because the index is lossy for this operator, so it has to be checked even if the bitmap didn't become lossy". You'd have to check the GIST opclass definition to be sure. regards, tom lane