X-Original-To: pgsql-performance@postgresql.org Received: from spampd.localdomain (postgresql.org [64.49.215.8]) by postgresql.org (Postfix) with ESMTP id 03118475AE5 for ; Fri, 9 May 2003 09:17:21 -0400 (EDT) Received: from matrix.gatewaynet.com (unknown [217.19.69.50]) by postgresql.org (Postfix) with ESMTP id EA72C475A80 for ; Fri, 9 May 2003 09:17:09 -0400 (EDT) Received: from matrix.gatewaynet.com (localhost [127.0.0.1]) by matrix.gatewaynet.com (8.12.5/8.12.5) with ESMTP id h49IMN1s007506; Fri, 9 May 2003 16:22:23 -0200 Received: from localhost (achill@localhost) by matrix.gatewaynet.com (8.12.5/8.12.5/Submit) with ESMTP id h49IMNaq007502; Fri, 9 May 2003 16:22:23 -0200 Date: Fri, 9 May 2003 16:22:23 -0200 (GMT+2) From: Achilleus Mantzios To: Tom Lane Cc: pgsql-performance@postgresql.org Subject: Re: An unresolved performance problem. In-Reply-To: <151.1052485680@sss.pgh.pa.us> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Status: No, hits=-38.4 required=5.0 tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, QUOTE_TWICE_1,REPLY_WITH_QUOTES,SIGNATURE_LONG_DENSE, USER_AGENT_PINE autolearn=ham version=2.50 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) X-Archive-Number: 200305/114 X-Sequence-Number: 1893 On Fri, 9 May 2003, Tom Lane wrote: > >> Well, it is surely no better than the correlation of the index's > >> first column --- what is that? > > > it is 1 > > Well, that's suggestive, isn't it? What about the remaining columns? The index is defined as: status_all btree (assettable, assetidval, appname, apptblname, status, isvalid) And correlations are: attname | correlation -------------+------------- assettable | 1 assetidval | 0.125902 appname | 0.942771 apptblname | 0.928761 status | 0.443405 isvalid | 0.970531 > > regards, tom lane > -- ================================================================== Achilleus Mantzios S/W Engineer IT dept Dynacom Tankers Mngmt Nikis 4, Glyfada Athens 16610 Greece tel: +30-210-8981112 fax: +30-210-8981877 email: achill@matrix.gatewaynet.com mantzios@softlab.ece.ntua.gr