BITMAP_CONSTRUCT_AGG¶
See: Understanding How Bitmaps Identify Distinct Values.
Syntax¶
BITMAP_CONSTRUCT_AGG( <bit_position> )
Parameters¶
bit_positionA numeric value that represents the BITMAP_BIT_POSITION of an input.
Returns¶
The function takes the relative position of multiple inputs in the bitmap, and returns a byte array that is a bitmap with bits set for each distinct input. The result should be grouped by BITMAP_BUCKET_OFFSET or BITMAP_BUCKET_NUMBER, so that values in different “buckets” are not merged together. For example:
SELECT BITMAP_BUCKET_OFFSET(UID) as offset, BITMAP_CONSTRUCT_AGG(BITMAP_BIT_POSITION(UID)) as bitmap FROM T
GROUP BY BITMAP_BUCKET_OFFSET(UID)
``UID = 0, 1, 9999, 10000, -1``
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