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 UAA29275 for postgres-dist; Thu, 24 Mar 1994 20:12:28 -0800 Resent-From: POSTGRES mailing list Resent-Message-Id: <199403250412.UAA29275@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 UAA29266 for ; Thu, 24 Mar 1994 20:12:27 -0800 Received: from localhost (localhost [127.0.0.1]) by faerie.CS.Berkeley.EDU (8.6.4/8.1B) with SMTP id UAA01877; Thu, 24 Mar 1994 20:11:26 -0800 Message-Id: <199403250411.UAA01877@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) Cc: kskim@hyowon.pusan.ac.kr (kim kyongsok), postgres@postgres.Berkeley.EDU, clcho@asadal.pusan.ac.kr, hwyun@hyowon.pusan.ac.kr, jhlee@asadal.pusan.ac.kr, yhkim@asadal.pusan.ac.kr, yjjeong@asadal.pusan.ac.kr Subject: Re: index and # of tuples Reply-To: aoki@postgres.Berkeley.EDU (Paul M. Aoki) Date: Thu, 24 Mar 94 20:11:26 -0800 X-Sender: aoki@postgres.Berkeley.EDU Resent-To: postgres-dist@postgres.Berkeley.EDU X-Mts: smtp Resent-Date: Thu, 24 Mar 94 20:12:28 -0800 Resent-XMts: smtp aoki@postgres.Berkeley.EDU (Paul M. Aoki) writes: > if you don't vacuum regularly, the optimizer has no statistics and > all plans cost the same. you get random plans. let me restate that. if you don't vacuum *at all* you have no statistics and get random plans. if you don't vacuum *regularly*, you have out-of-date statistics and the optimizer will make decisions based on bad assumptions rather than completely random ones. -- Paul M. Aoki | CS Div., Dept. of EECS, UCB | aoki@postgres.Berkeley.EDU | Berkeley, CA 94720 | ...!uunet!ucbvax!aoki