Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 721E12E005E for ; Wed, 26 Mar 2008 12:02:31 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 65141-01 for ; Wed, 26 Mar 2008 12:02:13 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.186]) by postgresql.org (Postfix) with ESMTP id 7FF222E0056 for ; Wed, 26 Mar 2008 12:02:12 -0300 (ADT) Received: from webserv.wug.de ([194.25.154.138]) by mrelayeu.kundenserver.de (node=mrelayeu2) with ESMTP (Nemesis) id 0MKwtQ-1JeX8j0wdH-0002aY; Wed, 26 Mar 2008 16:02:10 +0100 Received: from kretschmer by webserv.wug.de with local (Exim 3.36 #1) id 1JeX8i-0002z0-00 for pgsql-performance@postgresql.org; Wed, 26 Mar 2008 16:02:08 +0100 Date: Wed, 26 Mar 2008 16:02:08 +0100 From: "A. Kretschmer" To: pgsql-performance@postgresql.org Subject: Re: 1-/2-dimensional indexes for common columns, rationale? Message-ID: <20080326150208.GH27264@a-kretschmer.de> References: <47EA5B4D.5000300@geizhals.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47EA5B4D.5000300@geizhals.at> X-OS: Debian/GNU Linux - weil ich es mir Wert bin! User-Agent: Mutt/1.5.9i X-Provags-ID: V01U2FsdGVkX1/USa1qxy+J9+zUxtUM38g8vy5mDsV55YNxUed +/gh7Wsz5huPHxBe/MhF0G0Ed58zMCCtMaLaGQUX3LzeLOcMuz tsSoXicEblQyrmdBouzHQkB8SoA4vWF X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200803/484 X-Sequence-Number: 29438 am Wed, dem 26.03.2008, um 15:18:53 +0100 mailte Marinos Yannikos folgendes: > Hello, > > we have several indexes such as: > > create index foo1 on bla (a); > create index foo2 on bla (b); > create index foo3 on bla (a,b); > > They are all used often by frequently used queries (according to > pg_statio_user_indexes), but we need somewhat higher INSERT/UPDATE > performance (having tuned most other things) so we'd like to remove some. Which version do you have? Since 8.1 pg can use a so called 'bitmap index scan', because of this feature i guess you don't need the index foo3. (if you have 8.1 or higher) Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net