Re: Why CBO doesn't choose the low cost plan

hi:

I create a empty table with the same table/index structure in 9.2.0.5 & 8.1.7.4 test environments and exp/imp the table/index statistics into test environments.

The 9i test database still chose the bad index, but *8i test database chose the right plan.*

Even when I set the *ANONYMOUS_CE_IDX index's *statistics to very big value, it still chose the bad one.

I agree that this maybe a 9.2.0.5 bug.

On 7/19/06, Jared Still <jkstill_at_gmail.com> wrote:
>
> On 7/19/06, eagle fan <eagle.f_at_gmail.com> wrote:
>
> > hi:
> >
> > My oracle version is 9205 and optimizer_features_enable is set to 9.2.0.
> >
> > We have a query choose a bad plan.
> >
> > ...
> > What do you think?
> >
>
>
> I think it's a bug.
>
> Check MetaLink.
>
> A possible candidate is *Bug 4112254 - CBO may not choose best index for
> single table access with unpeeked bind/function*
>
> I just searched MetaLink on CBO Bug 9.2.0.5
>
> You should probably check there.
>
> --
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist
>

-- 
Eagle Fan

Oracle DBA

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