Re: how to evaluate optimizer_index_caching

I would say you only start chaning the optimizer_index_* parameters if:

• you've got good statistics in place
• your "normal" optimizer parameters are set correctly for your environment (pga, mode, etc)
• your system stats are accurate
• AND many of your sql's still get suboptimal execution plans

My colleague, christian antognini held a good presentation at last year's miracle db forum in denmark about the "CBO configuration roadmap" where he explains those as well -- google for it

Stefan

On 1/22/07, Polarski, Bernard <Bernard.Polarski_at_atosorigin.com> wrote:
>
> The question is : how do I known when I need to alter the default
> values.
>
> Bernard Polarski
> Oracle DBA
>
> -----Original Message-----
> From: Syed Jaffar Hussain [mailto:sjaffarhussain_at_gmail.com]
> Sent: maandag 22 januari 2007 12:39
> To: Polarski, Bernard
> Cc: oracle-l_at_freelists.org
> Subject: Re: how to evaluate optimizer_index_caching
>
> Bernard,
>
> I dont know whether my reply will be useful or you already might be
> knowing this.
>
> Tempering with OPTIMIZER_INDEX* parameter needs very careful testing
> and setting other than default value to OPTIMIZER_INDEX* would result
> favoring NESTED LOOP.
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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