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Message Posted: Wed, 23 Jun 2004 @ 09:31:29 GMT

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Hi,

Based on the experiment conducted, please see the answers.

Collect stats does not consider unique values if more than 1 column(Primary Index) is having null values, where as group by identifies it as unique values.

Consider table X with following rows.

        A       B       C       D
        1       2       3       5
        1       ?       ?       5
        1       7       3       7
        1       ?       3       6
        1       2       3       6
        1       ?       ?       2
        1       ?       3       7

Group by on A,B,C gives the output as

        A       B       C
        1       2       3
        1       ?       ?
        1       7       3
        1       ?       3

Where as after collecting the stats it displays only 3 unique values.

Hope this helps you..

Regards,

Vijay

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