Path: news.cambrium.nl!textnews.cambrium.nl!feeder3.cambriumusenet.nl!feed.tweaknews.nl!192.87.166.28.MISMATCH!tudelft.nl!txtfeed1.tudelft.nl!feeder.erje.net!news-1.dfn.de!news.dfn.de!news.informatik.hu-berlin.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Robert Klemme Newsgroups: comp.databases.oracle.server Subject: Re: The exact difference between SQL profile and baselines in Oracle 11 Date: Mon, 10 Oct 2011 19:09:08 +0200 Lines: 29 Message-ID: <9fgn5lF8pcU1@mid.individual.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net 908HWJLjc0zOBjDOvcY2Ng1p979y1aOY9HFXJMi/uR7GuTHfA= Cancel-Lock: sha1:LXMuUDE5yJ9sjSB8HqNELJNPve8= User-Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1 In-Reply-To: Xref: news.cambrium.nl On 10.10.2011 18:17, Mladen Gogala wrote: > I must say that I'm not quite clear about the conceptual differences > among the two. I know that SQL Profiles put in a lot of OPT_ESTIMATE > hints and adjust cardinality estimates. I know that baselines are > actually plans but their usage seems extremely similar. Can anyone shed > some light on the conceptual differences? I think a baseline contains the data on which profile creation is based: http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/autostat.htm#autoId15 The more abstract definition http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/perf_overview.htm#autoId4 As I understand it the baseline contains the base data which is used to identify critical SQL which then is further analyzed during maintenance windows. IIRC you can even have Oracle automatically accept new plans (probably stored in profiles) if the execution characteristics improve vs. the current plan. http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/sql_tune.htm#CHDHICFI Kind regards robert -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/