Re: Why CBO doesn't choose the low cost plan
- From: "eagle fan" <eagle.f@xxxxxxxxx>
- To: "Jared Still" <jkstill@xxxxxxxxx>, oracle-l@xxxxxxxxxxxxx
- Date: Thu, 20 Jul 2006 13:20:25 +0800
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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