RE: Optimizer issue

If is possible that for specific queries that the CBO could make an
incorrect choice for which index to use.  There are some bugs especially
related to ANSI join syntax where incorrect results can be produced so
depending on your Oracle database version and the manner in which the
vendor application is written there exists the possibility.  However, as
you posted the CBO seems to have gotten quite a bit of the application
SQL correct.
 
HTH -- Mark D Powell --
 


________________________________

        From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Manjula Krishnan
        Sent: Friday, May 19, 2006 11:05 AM
        To: oracle-l@xxxxxxxxxxxxx
        Subject: Optimizer issue
        
        
        I have an application on Oracle 9i. The database (designed by
the vendor) was set with optimizer_mode=CHOOSE. A week after we went
live with the application, performance started degrading. I discovered
that statistics were missing and built them. Immediately the application
problems were resolved. 
         
        The vendor claims that with the statistics, it would not use the
right indexes and some data would not be pulled up in the application.
Is that possible?
         
        Thanks,
         
        Manjula

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