Re: how to evaluate optimizer_index_caching
- From: "Stefan Knecht" <knecht.stefan@xxxxxxxxx>
- To: Bernard.Polarski@xxxxxxxxxxxxxx
- Date: Mon, 22 Jan 2007 13:38:42 +0100
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@xxxxxxxxxxxxxx> 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@xxxxxxxxx]
Sent: maandag 22 januari 2007 12:39
To: Polarski, Bernard
Cc: oracle-l@xxxxxxxxxxxxx
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.
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