Return-Path: owner-postman Received: from localhost (localhost [127.0.0.1]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with SMTP id SAA10041 for postgres-dist; Fri, 25 Mar 1994 18:53:55 -0800 Resent-From: POSTGRES mailing list Resent-Message-Id: <199403260253.SAA10041@nobozo.CS.Berkeley.EDU> Sender: owner-postman@postgres.Berkeley.EDU X-Return-Path: owner-postman Received: from faerie.CS.Berkeley.EDU (faerie.CS.Berkeley.EDU [128.32.149.14]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with ESMTP id SAA10032 for ; Fri, 25 Mar 1994 18:53:53 -0800 Received: from localhost (localhost [127.0.0.1]) by faerie.CS.Berkeley.EDU (8.6.4/8.1B) with SMTP id SAA02832; Fri, 25 Mar 1994 18:53:50 -0800 Message-Id: <199403260253.SAA02832@faerie.CS.Berkeley.EDU> X-Authentication-Warning: faerie.CS.Berkeley.EDU: Host localhost didn't use HELO protocol From: aoki@postgres.Berkeley.EDU (Paul M. Aoki) To: suresh@nlm.nih.gov (Suresh Srinivasan) Cc: postgres@postgres.Berkeley.EDU, rodgers@hume.nlm.nih.gov Subject: Re: Retrieve question Reply-To: aoki@postgres.Berkeley.EDU (Paul M. Aoki) Date: Fri, 25 Mar 94 18:53:50 -0800 X-Sender: aoki@postgres.Berkeley.EDU Resent-To: postgres-dist@postgres.Berkeley.EDU X-Mts: smtp Resent-Date: Fri, 25 Mar 94 18:53:55 -0800 Resent-XMts: smtp aoki@postgres.Berkeley.EDU (Paul M. Aoki) writes: > suresh@nlm.nih.gov (Suresh Srinivasan) writes: > > It seems that if the query is qualified by > > even a simple Boolean expression, the search > > defaults to a sequential scan rather than > > use the index. > you can have fairly complex AND/NOT expressions and use indices. > the key in your query is the OR. [blah blah blah, blah, blah blah blah blah...] to put it more consisely, you're absolutely right for OR clauses. the optimizer won't use an index with OR -- we don't keep the statistics it needs to make intelligent use of them so the corresponding code has just never been written. nor will it be, at this point. -- Paul M. Aoki | CS Div., Dept. of EECS, UCB | aoki@postgres.Berkeley.EDU | Berkeley, CA 94720 | ...!uunet!ucbvax!aoki