Re: stored outlines used but wrong plan executed

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Hi Jonathan

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:cij66p$pe$1_at_hercules.btinternet.com... [...]
> "Christian Antognini" <christian.antognini_at_trivadis.com> wrote in message
> news:414b112d_at_post.usenet.com...
> >
> > I already had similar problems. Since outlines are hints and, like any
> > hints, sometimes the CBO decide not using them, it happens that an
outline
> > simply doesn't work :-(
> >
>
> You've got the argument the wrong way round.

My guess was that the modifications were performed in SQL*Plus... (and in fact it was) Of course it is possible, but in practice is very difficult to get a "stable" set of hints! For this reason I always use, and I recommend to use, the Outline Editor.

> Since outlines are hints, we can infer that a complete
> and legal set of hints cannot be ignored by the optimiser.

If a complete and legal set of hints is used I basically agree with you. Why basically? Because I already seen situations (fortunately rarely) where it is not the case! e.g. by copying outlines from one database (test) to another (production).

> > How did you modify the outline? If you used the Outline Editor, did you
> get
> > the "correct" plan when you tried to validate the changes?
> >
>
> Excellent question - and the other important question is:
> "How did the OP decide that Oracle was using the
> outline ?"

Chris

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