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@xxxxxxxxx> wrote: 

On 7/19/06, eagle fan <eagle.f@xxxxxxxxx> 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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