Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id AF35A2E004A for ; Wed, 26 Mar 2008 12:25:39 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 59835-02 for ; Wed, 26 Mar 2008 12:25:26 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.171]) by postgresql.org (Postfix) with ESMTP id E879B2E005A for ; Wed, 26 Mar 2008 12:25:25 -0300 (ADT) Received: from webserv.wug.de ([194.25.154.138]) by mrelayeu.kundenserver.de (node=mrelayeu0) with ESMTP (Nemesis) id 0MKwh2-1JeXV80Eti-0007wB; Wed, 26 Mar 2008 16:25:21 +0100 Received: from kretschmer by webserv.wug.de with local (Exim 3.36 #1) id 1JeXV8-00039Y-00 for pgsql-performance@postgresql.org; Wed, 26 Mar 2008 16:25:18 +0100 Date: Wed, 26 Mar 2008 16:25:18 +0100 From: "A. Kretschmer" To: pgsql-performance@postgresql.org Subject: Re: 1-/2-dimensional indexes for common columns, rationale? Message-ID: <20080326152518.GI27264@a-kretschmer.de> References: <47EA5B4D.5000300@geizhals.at> <20080326150208.GH27264@a-kretschmer.de> <47EA6888.2050506@geizhals.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47EA6888.2050506@geizhals.at> X-OS: Debian/GNU Linux - weil ich es mir Wert bin! User-Agent: Mutt/1.5.9i X-Provags-ID: V01U2FsdGVkX18ujkVqDeBRgkkQE0vt9KimbJhRAYg4kpmJFVC bYUDcFUiVKpjDdozP6dT0bBE95nneH6xlq1zvOubSaRj2bcLJ/ mVUFipC+VnYxWiK4epiU40J9KoLBtD/ X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200803/487 X-Sequence-Number: 29441 am Wed, dem 26.03.2008, um 16:15:20 +0100 mailte Marinos Yannikos folgendes: > A. Kretschmer schrieb: > >>create index foo1 on bla (a); > >>create index foo2 on bla (b); > >>create index foo3 on bla (a,b); > >>[...] > > > >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) > > 8.3.1 - foo3 is being used though in presence of both foo1 and foo2, so > I'd suppose that it's a better choice even with bitmap index scan > available... Maybe... Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net