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Archives of the TeradataForum
Message Posted: Tue, 24 Feb 2004 @ 10:45:41 GMT
Subj: | | Re: Insert/Select taking too much time |
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From: | | David Wellman |
Hi Nitin,
Check the distribution of the answer set based around the primary index of the target table. The target table is defined as SET but with no
UNIQUE indexes on it, this is not bad but it means that the DBMS has to do duplicate row checks. With lots of rows for the same primary index data
value this can be very expensive. This will typically be the biggest difference between your select and the insert/select. Ignoring the dup row
check, I'd also check the distribution anyway, this may not show up in the select but may start to cause problems in the insert/select.
Cheers,
Dave
Ward Analytics Ltd: Information in motion ( www.ward-analytics.com )
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