Received: from localhost (postgresql.org [64.49.215.8]) by postgresql.org (Postfix) with ESMTP id 59829475E60 for ; Thu, 3 Oct 2002 03:07:31 -0400 (EDT) Received: from email02.aon.at (WARSL402PIP7.highway.telekom.at [195.3.96.94]) by postgresql.org (Postfix) with SMTP id 23598475BC3 for ; Thu, 3 Oct 2002 03:07:30 -0400 (EDT) Received: (qmail 47812 invoked from network); 3 Oct 2002 07:07:30 -0000 Received: from m152p003.dipool.highway.telekom.at (HELO cantor) ([62.46.8.227]) (envelope-sender ) by qmail2rs.highway.telekom.at (qmail-ldap-1.03) with SMTP for ; 3 Oct 2002 07:07:30 -0000 From: Manfred Koizar To: Tom Lane Cc: pgsql-hackers@postgresql.org Subject: Re: Correlation in cost_index() Date: Thu, 03 Oct 2002 09:09:49 +0200 Message-ID: <3mpnpuccoukikseed1e3pedo5t1dfj64cn@4ax.com> References: <29475.1033598929@sss.pgh.pa.us> In-Reply-To: <29475.1033598929@sss.pgh.pa.us> X-Mailer: Forte Agent 1.8/32.548 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Scanned: by AMaViS new-20020517 X-Archive-Number: 200210/101 X-Sequence-Number: 29870 On Wed, 02 Oct 2002 18:48:49 -0400, Tom Lane wrote: >I don't think it's really a good idea to expect users to pick among >multiple cost functions The idea is that PG is shipped with a default representing the best of our knowledge and users are not encouraged to change it. When a user sends a "PG does not use my index" or "Why doesn't it scan sequentially?" message to one of the support lists, we advise her/him to set index_cost_algorithm to 3 (or whatever we feel appropriate) and watch the feedback we get. We don't risk anything, if the default is the current behaviour. Servus Manfred