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Archives of the TeradataForum
Message Posted: Wed, 17 Nov 2004 @ 20:56:57 GMT
| Subj: | | PMON explain for running query - Large discrepancy between "Estimated I/O" and "Actual I/O" |
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| 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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