Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 3EAA09FB9FF for ; Thu, 15 Feb 2007 20:32:50 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-new, port 10024) with ESMTP id 57596-07 for ; Thu, 15 Feb 2007 20:32:38 -0400 (AST) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.4 Received: from wr-out-0506.google.com (wr-out-0506.google.com [64.233.184.226]) by postgresql.org (Postfix) with ESMTP id 287E59FB792 for ; Thu, 15 Feb 2007 20:32:43 -0400 (AST) Received: by wr-out-0506.google.com with SMTP id i7so1171567wra for ; Thu, 15 Feb 2007 16:32:42 -0800 (PST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=JrwUwyxDoyIz3XEb6NcKUDnEY0ccbSOhQQlB01a87LPWyFn5lmrRR//Vx84L92c/IpDNJoPSqgyVL0v5VxQlKlIV2jPLoTU8b8A3b3azXOwnoET/+tT8DN3AaO5Bd+2z/XY2PISIYVFnxmJyIedSDbqYYMPxFznwovKTLNVboT4= Received: by 10.90.90.16 with SMTP id n16mr3488237agb.1171585962096; Thu, 15 Feb 2007 16:32:42 -0800 (PST) Received: by 10.90.113.7 with HTTP; Thu, 15 Feb 2007 16:32:42 -0800 (PST) Message-ID: <1d4e0c10702151632o3846869rddb0a9f83adfcadd@mail.gmail.com> Date: Fri, 16 Feb 2007 01:32:42 +0100 From: "Guillaume Smet" To: "Tom Lane" Subject: Re: Question about Bitmap Heap Scan/BitmapAnd Cc: "Alvaro Herrera" , pgsql-performance@postgresql.org In-Reply-To: <1d4e0c10702151009n54772ac0rece99a7af35f3399@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline 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> <26633.1171557289@sss.pgh.pa.us> <1d4e0c10702151009n54772ac0rece99a7af35f3399@mail.gmail.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200702/178 X-Sequence-Number: 23232 On 2/15/07, Guillaume Smet wrote: > On 2/15/07, Tom Lane wrote: > > 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. FYI I've taken a look at PostGIS source code and the index is lossy for the operator &&: OPERATOR 3 && RECHECK, (for every operator in the opclass to be exact) -- Guillaume