Return-Path: Received: from ensim.rackshack.net (root@localhost) by orafaq.net (8.11.6/8.11.6) with ESMTP id h45KWUv26067 for ; Mon, 5 May 2003 15:32:30 -0500 X-ClientAddr: 209.68.248.164 Received: from newsfeed.cts.com (newsfeed.cts.com [209.68.248.164]) by ensim.rackshack.net (8.11.6/8.11.6) with ESMTP id h45KWTA26059 for ; Mon, 5 May 2003 15:32:29 -0500 Received: from fatcity.com (uucp@localhost) by newsfeed.cts.com (8.9.3/8.9.3) with UUCP id LAA81018; Mon, 5 May 2003 11:07:16 -0700 (PDT) Received: by fatcity.com (26-Feb-2001/v1.0g-b72/bab) via UUCP id 0058FE80; Mon, 05 May 2003 10:49:45 -0800 Message-ID: Date: Mon, 05 May 2003 10:49:45 -0800 To: Multiple recipients of list ORACLE-L X-Comment: Oracle RDBMS Community Forum X-Sender: "Jonathan Lewis" Sender: root@fatcity.com Reply-To: ORACLE-L@fatcity.com Errors-To: ML-ERRORS@fatcity.com From: "Jonathan Lewis" Subject: Re: which should be faster Organization: Fat City Network Services, San Diego, California X-ListServer: v1.0g, build 72; ListGuru (c) 1996-2001 Bruce A. Bergman Precedence: bulk Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit I suspect that this comment is highly context-sensitive. Oracle 9 can re-arrange the order of filter predicates to reduce the estimated cost of a query. Oracle 8 cannot. Note - it is implicit in the software that the order of predicates can have an impact on the performance of a query, otherwise there would be no need for the /*+ ordered_predicates */ hint. On the other hand, the order of the (simple filter) predicates cannot affect the calculated cost of a query prior to 9i, because the calculated cost is I/O based, not CPU based. Regards Jonathan Lewis http://www.jlcomp.demon.co.uk The educated person is not the person who can answer the questions, but the person who can question the answers -- T. Schick Jr One-day tutorials: http://www.jlcomp.demon.co.uk/tutorial.html ____Denmark__May 21-23rd ____Sweden___June ____Finland__September ____Norway___September Three-day seminar: see http://www.jlcomp.demon.co.uk/seminar.html ____UK_(Manchester)_May x 2 ____Estonia___June (provisional) ____Australia_June (provisional) ____USA_(CA, TX)_August The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" Sent: 05 May 2003 16:52 > I've check on asktom and he is positive that the order of predicate has no > impact (DB version for that comment is 815). > From the site : > > No, the order of evaluation of a predicate in SQL is purposely > "indeterminate". > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jonathan Lewis INET: jonathan@jlcomp.demon.co.uk Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).