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Message Posted: Wed, 17 Nov 2004 @ 20:56:57 GMT


     
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Subj:   PMON explain for running query - Large discrepancy between "Estimated I/O" and "Actual I/O"
 
From:   Anomy Anom

<-- Anonymously Posted: Wednesday, November 17, 2004 13:53 -->

After upgrading to V2R5, when viewing explain plans in PMON for queries that are currently running, we have noticed HUGE discrepancies between the "Estimated I/O" and "Actual I/O" numbers (PMON shows these on a per step basis). Has anyone else seen this? If so, did you determine the cause? If the optimizer is estimating I/O that badly, it stands to reason that the optimizer would, in turn, be generating bad execution plans.



     
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