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Aggregate functions (Counting Distinct Values)
BITMAP_COUNT¶
Given a bitmap that represents the set of distinct values for a column, returns the number of distinct value.
Syntax¶
BITMAP_COUNT( <bitmap> )
Arguments¶
bitmap
This expression must evaluate to a bitmap returned by the BITMAP_CONSTRUCT_AGG or BITMAP_OR_AGG functions.
Returns¶
The function returns the number of distinct values in a column, as represented by the bits set in the input bitmap.
Examples¶
See Using Bitmaps to Compute Distinct Values for Hierarchical Aggregations.