Path: news.easynews.com!easynews!news.he.net!cyclone-sf.pbi.net!199.106.71.17!pln-w!spln!dex!extra.newsguy.com!newsp.newsguy.com!enews1 From: Michael Brown Newsgroups: comp.databases.oracle.server,comp.databases.oracle.tools Subject: Re: Help: Is cost of explain plan reliable? Date: Tue, 23 Apr 2002 13:17:28 -0400 Organization: http://extra.newsguy.com Lines: 19 Message-ID: References: <3cc080a9@news.victoria.tc.ca> NNTP-Posting-Host: p-995.newsdawg.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Newsreader: Forte Agent 1.91/32.564 Xref: easynews comp.databases.oracle.server:144246 comp.databases.oracle.tools:50873 X-Received-Date: Tue, 23 Apr 2002 10:36:22 MST (news.easynews.com) On 22 Apr 2002 07:24:51 -0700, mfowler@dot.co.pima.az.us (m. fowler) wrote: >It's recommended that DBMS_STATS be used in place of ANALYZE, >depending on your version - let the db decide what needs to be >analyzed, how much data to look at, how many buckets and so on. > On some platforms 'ANALYZE TABLE' is a fancy form of Russian Roulette, there is bug that is sometimes hit during analyze table which generates an ORA- error (probably 600, but I don't remember). If you hit this bug, then there is a chance that your database will halt. Luckily when I learned about this bug, I only had the error message. DBMS_STATS uses a different mechanism to collect the table statistics which is safe and 'ANALYZE INDEX' is apparently safe. >> Run the ANALYSE command to bring the statistics up to date. Run the >> analyse frequently enough to keep them up to date. I notice that the >> people I work with always re-analyse everything once per day. Don't know >> if its recommended anywhere, but that's what they do.