Re: SKEWONLY' WORKS !!!!!!!!

From: Wolfgang Breitling <breitliw_at_centrexcc.com>
Date: Fri, 13 Aug 2004 10:23:46 -0600
Message-Id: <6.1.0.6.2.20040813101544.0302d7e0@pop.centrexcc.com>

Instead of "SIZE SKEWONLY", I would use "SIZE AUTO". It collects the same histograms as skewonly, but while skewonly will create a histogram for any column which is skewed enough, "auto" will do it only for columns which may benefit from a histogram, i.e. columns used in predicates.

Of course, I prefer not to use either, but collect histograms for selected columns with individualized numbers of buckets.

At 09:42 AM 8/13/2004, you wrote:

>Then all the useres started to complaint somep rocess were slower, some of
>them were 100% slower, then I gather againt histogram statistics and all
>return to normality.
>EXEC DBMS_STATS.GATHER_database_STATS( ESTIMATE_PERCENT=>100,METHOD_OPT=>
>FOR ALL COLUMNS SIZE SKEWONLY');
>
>So based on my experience in 9.2, if you don't use histograms, try to run
>this command and see if you get some performance (test it )
>
>Juan Carlos Reyes Pacheco
>OCP
Regards

Wolfgang Breitling
Centrex Consulting Corporation
www.centrexcc.com

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Received on Fri Aug 13 2004 - 11:19:33 CDT