RE: Should we stop analyzing?

Wolfgang,
I don't have 9i available at the moment so I can't test this. Just wondering if a 10053 trace shows you if the statistics it is using are gathered from dynamic sampling.

Henry

-----Original Message-----
Wolfgang Breitling
Sent: Tuesday, December 30, 2003 6:24 PM To: Multiple recipients of list ORACLE-L

The CBO will do dynamic sampling automatically provided the conditions are met. The conditions that need to be met depend on the dynamic_sampling initialization parameter in effect for the session. The default is 1 which practically disables dynamic sampling. 0 will totally disable it but IMHO the conditions for dynamic_sampling=1 are so rare (in practice) that one can regard it as off.
BTW, even if the CBO goes to dynamic sampling that does not guarantee that it will use the statistics it did gather this way.

At 03:24 PM 12/30/2003, you wrote:
>Tanel,
>
>I know the values, you are missing my question ... let me re-phrase it ...
>
>1. To have CBO use dynamic sampling do you have to specify the hint?
>or
>2. CBO will do that automatically?
>
>Just to let you know, Oracle 9ir2 docs main page is my home page on
>Mozilla firebird browser and Metalink is my homepage on IE.
>Raj
>-------------------------------------------------------------------------------
-
>Rajendra dot Jamadagni at nospamespn dot com
>All Views expressed in this email are strictly personal.
>QOTD: Any clod can have facts, having an opinion is an art !
>
>
>-----Original Message-----
>Sent: Tuesday, December 30, 2003 2:44 PM
>To: Multiple recipients of list ORACLE-L
>
>
>Go to tahiti.oracle.com and search for the optimizer_dynamic_sampling
>parameter, you'll see descriptions for it's different values there.
>
>Tanel.
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
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> INET: Rajendra.Jamadagni_at_espn.com
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Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

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