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RE: Changes to RULE based optimizer between Oracle8 and 9i

From: Bobak, Mark <Mark.Bobak_at_il.proquest.com>
Date: Fri, 30 Jan 2004 12:08:19 -0500
Message-ID: <4C9B6FDA0B06FE4DAF5918BBF0AD82CFBFD55D@bosmail00.bos.il.pqe>


Keith,  

To my knowledge, RBO has not changed. That includes NOT dealing w/ IOT. So, I think if you execute a query that references an IOT, you'll implicitly invoke the CBO. That would explain why the plan is changing. So, did you change a table from heap to IOT when you moved to 9i? If so, that's what's invoking CBO.  

-Mark
 

PS fatcity is going away, use freelists.org!    

Mark J. Bobak
Oracle DBA
ProQuest Company
Ann Arbor, MI
"Imagination was given to man to compensate him for what he is not, and a sense of humor was provided to console him for what he is." --Horace Walpole

	-----Original Message-----
	From: Keith Moore [mailto:kmoore7_at_jcpenney.com] 
	Sent: Friday, January 30, 2004 11:54 AM
	To: Multiple recipients of list ORACLE-L
	Subject: Changes to RULE based optimizer between Oracle8 and 9i
	
	
	We move an application that uses OPTIMIZER_MODE=RULE from
Oracle8 to 9i. Most of it is fine, but there are two queries that have a very different execution plan. In one case, the execution time increases from less than a minute to more than an hour. Neither query uses any of the new Oracle 9i features.          

        My understanding is that the Rule optimizer code has not changed, except to account for new features like IOT's. Has anyone else seen this type of behavior?          

	Keith Moore
	Oracle Certified Professional
	972-431-5126
	kmoore7_at_jcpenney.com



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Received on Fri Jan 30 2004 - 11:08:19 CST

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