Re: How to make query avoid using histograms
- From: rjamya <rjamya@xxxxxxxxx>
- To: Niall Litchfield <niall.litchfield@xxxxxxxxx>
- Date: Wed, 27 Apr 2005 07:27:17 -0400
we found that this query takes slightly different execution paths based no
input parameters (most number), turning off bind variable peeking and
changing cs=exact didn't help. That's why I wanted to find out what would
happen, if somehow I could turn off usage of histograms for this query.
Christian, RULE hint didn't help either.
Raj
On 4/27/05, Niall Litchfield <niall.litchfield@xxxxxxxxx> wrote:
>
> On 4/26/05, Lex de Haan <lex.de.haan@xxxxxxxxxxxxxx> wrote:
> > you can't -- if histograms are available, they will be used.
> > of course, you can use various hints and/or session settings
> > to influence the optimizer.
> > just out of curiosity: why would you, in the presence of histograms,
> > ever want to tell the optimizer *not* to use them?
>
> Because you issue a report with bind variables that for 99% of its
> executions *should* use histograms, but for 1% of them - the report to
> the board say, shouldn't use the execution path generated with
> histograms, and bind variable peeking isn't in operation. I don't
> think this applies to 9204 though.
>
> --
> Niall Litchfield
> Oracle DBA
> http://www.niall.litchfield.dial.pipex.com
>
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