RE: DBMS_STATS [resend chomped version]

Expect changes in execution plans, possibly not for the better.

I had at one time collected histograms for all indexed columns on
a problem database, and was convinced that this shotgun approach
is not really a good idea.

Currently, we aren't collecting any histograms, IIRC.

Jared




Barbara Baker <barbarabbaker@xxxxxxxxx> 
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06/16/2004 03:12 PM
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RE:  DBMS_STATS [resend chomped version]






Regarding #1:
(9.2.0.4 Solaris 9)
We have a recommendation from the sw vendor to compute
with histograms using

exec dbms_stats.gather_schema_stats(ownname =>
'SCOTT', estimate_percent =>
dbms_stats.auto_sample_size, method_opt => 'for all
columns size skewonly', cascade => true);

as an initial method to gather the stats. I did a bit
of looking and a bit of testing, and it looks good to
me.  Down side:  it did take several hours to gather
the initial set of stats.

What are other folks doing with histograms??

Barb

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