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Archives of the TeradataForum
Message Posted: Wed, 05 May 2004 @ 19:56:34 GMT
| Subj: | | Re: Collect Stats on Indexes versus Multi-Column |
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| From: | | Dieter Noeth |
Claybourne Barrineau wrote:
TableA
ColA
ColB
ColC
ColD
UPI = ColA
Index (ColB, ColC)
| | Are the following 2 statements equivalent to the RDBMS? | |
| | 1)Collect Stats on TableA Index (ColB, ColC); | |
| | 2)Collect Stats on TableB Column (ColB, ColC); | |
| | From an 'Explain' point of view, they look identical. | |
There's a difference:
You can drop and recreate that index without losing statistics (similar to a single column index), if you collect on multi-column,
because those statistics are stored as a pseudo-index (with indextype 'M') in dbc.indexes.
Dieter
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