Re: How to calibrate the CBO

"DBA Infopower Support" <support_at_dbainfopower.com> wrote in message news:YI2dnc6W5-CDH7nd4p2dnA_at_comcast.com...
>
> Hello Rick,
>
> Tuning CBO correctly is relatively difficult task.
>
> Optimizer uses many documented and undocumented parameter that impact
> it's decision tree.
>
> One of the important parameters to tune is "optimizer_index_cost_adj".
>
> Check below link for some good recommendations:
> http://www.dba-oracle.com/oracle_tips_cost_adj.htm

Hmm, not a good article. There is no such thing as a silver bullet and it doesn't actually explain what is going on particularly well. Advice that says 'change this parameter its a silver bullet' ought to be highly distrusted.

> Mark Rittman's Oracle Weblog has good info as well -
> http://www.rittman.net/archives/000701.html

These papers (by Wolfgang Breitling www.centrexcc.com not Mark btw) on the other hand are excellent.

--
Niall Litchfield
Oracle DBA
Audit Commission UK
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