Re: Performance of DBMS_STATS vs ANALYZE
- From: Charlotte Hammond <charlottejanehammond@xxxxxxxxx>
- To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 21 May 2004 03:21:00 -0700 (PDT)
Hi Connor
--- Connor McDonald wrote: >
Notice that your analyze command did not calculate column stats, but the
dbms_stats did. You'll
get a "fairer" assessment if you analyze command is:
ANALYZE TABLE myschema.<table> ESTIMATE STATISTICS SAMPLE <<n>> PERCENT
FOR TABLE FOR ALL INDEXES
for all columns size 1;
--
Thanks for the suggestion - if I gather columns stats using ANALYZE it does
slow things down a bit. It is still 2x faster than DBMS_STATS, but not 3 or 4x
as it was before.
But ideally I'd like make DBMS_STATS faster, not ANALYZE slower :-)
Are these 1-bucket histograms on each column useful to the CBO? If not, can
they be turned off (METHOD_OPT=>'FOR ALL COLUMNS SIZE 0' doesn't do anything).
As Jonathan Lewis also suggested, perhaps I'm dwelling on this more than I need
to - but I'm curious!
Thanks
- Charlotte
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