Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id DA9F69FB39F for ; Tue, 17 Oct 2006 08:45:25 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 37735-04 for ; Tue, 17 Oct 2006 08:45:20 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.171]) by postgresql.org (Postfix) with ESMTP id 4EAA79FB25B for ; Tue, 17 Oct 2006 08:45:19 -0300 (ADT) Received: from [194.25.154.138] (helo=webserv.wug.de) by mrelayeu.kundenserver.de (node=mrelayeu6) with ESMTP (Nemesis), id 0ML29c-1GZnNg2GM6-00005W; Tue, 17 Oct 2006 13:45:12 +0200 Received: from kretschmer by webserv.wug.de with local (Exim 3.36 #1) id 1GZnNf-0007dC-00 for pgsql-performance@postgresql.org; Tue, 17 Oct 2006 13:45:11 +0200 Date: Tue, 17 Oct 2006 13:45:11 +0200 From: "A. Kretschmer" To: pgsql-performance@postgresql.org Subject: Re: Regarding Bitmap Scan Message-ID: <20061017114511.GD19268@a-kretschmer.de> References: <9f2e40a90610170439n4b670c23ld586e4f0840e943@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9f2e40a90610170439n4b670c23ld586e4f0840e943@mail.gmail.com> X-OS: Debian/GNU Linux - weil ich es mir Wert bin! X-Message-Flag: "Windows" is not the answer. "Windows" is the question and the answer is "no"! User-Agent: Mutt/1.5.9i X-Provags-ID: kundenserver.de abuse@kundenserver.de login:51ea9561fc3f6d9539a2acd743e4748c X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.338 tagged_above=0 required=5 tests=AWL, SPF_HELO_PASS X-Spam-Level: X-Archive-Number: 200610/321 X-Sequence-Number: 21450 am Tue, dem 17.10.2006, um 17:09:29 +0530 mailte soni de folgendes: > I didn't understand the "Bitmap Scan" and the sentence "indexes will be > dynamically converted to bitmaps in memory". What does mean by "Bitmap Scan" in > database? For instance, you have a large table with 5 indexes on this and a query that checks conditions on this 5 columns. PG is now able to combine this 5 indexes and performs only 1 bitmap index scan on this table, and not 5 independet nested bitmap scans. A realy very great performance-boost! HTH, Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47215, D1: 0160/7141639 (mehr: -> Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net