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Message Posted: Wed, 08 May 2002 @ 13:28:42 GMT


     
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Subj:   Re: Value Order Indexes
 
From:   Ruth Fenwick

Tony,

I find the optimizer is very sensitive to new values in an index, especially date fields. With a value ordered index, the optimizer KNOWs the highest value, when you add another day, and don't tell it, it assumes that there is no value for that day and it would return no rows for that part of the query.....choosing what is obviously a bad path....

To avoid this very problem, I actually collect stats on all my date fields (columns and indexes) every night. Adds a bit to the batch schedule, but pays off the next day with the on-lines.

Ruth Fenwick
IA&DSS Team Leader, IRM
Hudson's Bay Company



     
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