That's true provided you're not using any of the new
features introduced in 8.0, and later versions, that
automatically cause the CBO to be used (e.g.
partitioning, degree or instances > 1, IOT, etc...)
When in doubt, I always check metalink note: 66484.1.
HTH,
- Anita
- Jon Walthour <jonw_at_fuse.net> wrote:
> Volker:
>
> If optimizer_mode = 'choose', then the optimizer
> chooses between
> cost-based optimization and rule-based optimization
> based on whether or
> not statistics are present. In your case, since they
> aren't it's using
> rule-based.
>
> -----Original Message-----
> Volker
> Sent: Thursday, August 16, 2001 4:46 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Hi list,
>
> a quick question about oracle optimizer.
>
> a customer has database migrated from 7.3.4 to 8.1.6
> on AIX. Data was
> transfered via full exp/imp. After migration the
> performance of the new
> database is very poor. I looked at the parameters
> and saw that no object
> is analyzed. So now me question:
>
> What does oracle optimizer do, if there are no
> statistics on all
> objects. Optimizer level is choose.
>
> Volker Schön
> E-Mail: mailto:v.schoen_at_inplan.de
> http://www.inplan.de
>
>
> --
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> Author: Schoen Volker
> INET: v.schoen_at_inplan.de
>
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Received on Sat Aug 18 2001 - 07:48:40 CDT
