RE: Optimizer issue

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Fri, 19 May 2006 11:37:27 -0400
Message-ID: <5A14AF34CFF8AD44A44891F7C9FF41050752D2F7@usahm236.amer.corp.eds.com>

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 --  

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        From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Manjula Krishnan

	Sent: Friday, May 19, 2006 11:05 AM
	To: oracle-l_at_freelists.org
	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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Received on Fri May 19 2006 - 10:37:27 CDT