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Re: EXPLAIN PLAN : better with RULE!

From: Telemachus <telemachus_at_ulysseswillreturn.net>
Date: Tue, 23 Jul 2002 15:09:08 +0100
Message-ID: <8sd%8.4313$zX3.3439@news.indigo.ie>


the Oracle Reference is what you want .... Additionally have a look at some of the documentation in Supplied Packages regarding DBMS_STATS "Steve Mitchell" <stevem_at_hdcsi.com> wrote in message news:%XW_8.275$gj.10765458_at_newssvr21.news.prodigy.com...
>
> "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message
> news:1027158123.29738.1.nnrp-14.9e984b29_at_news.demon.co.uk...
> >
> > Rather than just fiddling with parameters though, the
> > next thing to do is look at the indexes and columns
> > that the RBO has used in its plan, and examine the
> > statistics stored in user_indexes, user_tab_columns,
> > and user_histograms to see why CBO doesn't like
> > them. Also check the stats against the real data
> > to see if the stats are misleading.
> >
>
> Great idea,
>
> Do you know where I might find some reference that would help me
> understand the statistics stored in user_indexes, user_tab_columns, and
> user_histograms? I would like to better understand how these
> fit together to get an idea of why the CBO is ignoring indexes that are
> obviously a better choice.
>
> > --
> > Jonathan Lewis
> > http://www.jlcomp.demon.co.uk
> >
>
>
> --steve
>
>
Received on Tue Jul 23 2002 - 09:09:08 CDT

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