Re: System Statistics and the CBO

John Smiley wrote:

> Mladen,
>
> She was asking why the CBO chose a different index with system stats
> than without. By comparing the traces from each case, she will find
> the answer. A 10053 trace is a dump of the decision tree used by the
> CBO to arrive at an execution plan. It is an outstanding tool in
> gaining a better understanding of CBO behaviour.
>
> Patty,
>
> If you'll also provide the output from autotrace with statistics from
> each case, that will provide valuable information as well. In fact, a
> 10046 level 12 trace for each case would be even better, but may be
> too large to send to the group. Feel free to send them directly to me
> if you like.
>

But a 10046 trace will not tell you WHY the optimizer chose one plan over another. It tells you where the time is spent executing the chosen plan.

-- 
Regards

Wolfgang Breitling
Centrex Consulting Corporation
www.centrexcc.com
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