RE: Should we stop analyzing?

Yes, it does.

extract from 10053 trace:

• Executed dynamic sampling query: level : 2 sample pct. : 11.151079 actual sample size : 2601 filtered sample card. : 2601 orig. card. : 11321 block cnt. : 278 max. sample block cnt. : 32 sample block cnt. : 31 ndv C3 : 12 scaled : 12.00 min. sel. est. : -1.0000
• Using dynamic sampling NDV estimates. Scaled NDVs using cardinality = 23325.
• Using dynamic sampling card. : 23325

It also tells you if it does NOT use the dynamic sampling results. Couldn't find an example right now.

At 07:59 AM 12/31/2003, you wrote:
>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
> >--
> >Author: Jamadagni, Rajendra
> > INET: Rajendra.Jamadagni_at_espn.com
> >
> >Fat City Network Services -- 858-538-5051 http://www.fatcity.com
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>
>Wolfgang Breitling
>Oracle7, 8, 8i, 9i OCP DBA
>Centrex Consulting Corporation
>http://www.centrexcc.com
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: Wolfgang Breitling
> INET: breitliw_at_centrexcc.com
>
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>Author: Poras, Henry R.
> INET: Henry_Poras_at_dfci.harvard.edu
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Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Wolfgang Breitling
  INET: breitliw_at_centrexcc.com

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