Re: Should we stop analyzing?

Note inline

At 10:29 PM 12/30/2003, you wrote:

>If my data changes, and I analyze it, CBO should still find
>reasonable execution paths for the current data.

If the CBO were infallable we wouldn't have this discussion. There are many reasons why even the most up-to-date statistics can lead to less than optimal access plans. My point is not necessarily with the frequency of statistics gathering but with the untested activation of new statistics, which is the hallmark of scheduled analyze jobs, as it carries the same risk as any untested change.

>If my data does not change, and I analyze it, CBO should have
>the same set of statistics as it did previously.

If your data didn't change, or didn't change enough to make a difference in access plans, wouldn't you agree that the exercise of gathering statistics was futile and useless.

>Is that not true, or is there some other piece missing here?

If the current statistics produce access plans that render the required data in the time stipulated by your SLAs, why the urge to change something. You are getting dangerously close to symptoms of CTD. If, on the other hand, there are performance problems, they should be analyzed case by case and at that time the possibility that newer statistics will change the access plan and improve the performance should be explored.

>Jared
>
>--
>Author: Jared Still
> INET: jkstill_at_cybcon.com

Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

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