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Archives of the TeradataForum
Message Posted: Thu, 19 Nov 2004 @ 02:24:36 GMT
| Subj: | | Re: PMON explain for running query - Large discrepancy between "Estimated I/O" and "Actual I/O" |
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| From: | | Andrew Schroter |
You can also query a dbc view while the query is stuck in a step to see what kind of skew you're seeing in spool. Set the query to retrieve
amp usage for each amp, not a total for all amps. The step may be redistributing rows where one of the next step's JOIN columns is non-unique,
such as lots of NULLS. Believe me, I've seen that happen.
Andy
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