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Message Posted: Wed, 30 Apr 2003 @ 01:05:25 GMT

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One thing I am surprised nobody mentioned is the V2R5 feature whereby you can collect statistics on a sample of the data (i.e. less than 100%). Perhaps we have very few V2R5 users on this list...

This can radically decrease the time required to refresh stats, although I've observed the exact information collected is not identical to what is collected during a regular "collect statistics".

The percentage of data scanned is determined by the system and depends on cardinality and skew - this will typically be between 1% and 10% of the table (according to the manual).

Syntax:

COLLECT STATISTICS USING SAMPLE ON ...

Once you collect statistics in this mode (sample) they will be recollected in the same mode when you issue subsequent collect statistics statements.

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