BITMAP_UNION_COUNT

Overview

Performs a union aggregation over a column of BITMAP objects and returns the cardinality (number of distinct elements) of the union directly. Equivalent to BITMAP_COUNT(BITMAP_UNION(...)), but more concise.

Syntax

BITMAP_UNION_COUNT(<bitmap_col>)

Parameters

• <bitmap_col>: A column of BITMAP type.

Examples

-- Count distinct elements in the union SELECT bitmap_union_count(b) FROM ( VALUES (to_bitmap(1)), (to_bitmap(2)), (to_bitmap(1)) ) t(b); -- 2 -- With GROUP BY SELECT k, bitmap_union_count(b) FROM ( VALUES ('x', to_bitmap(1)), ('x', to_bitmap(2)), ('y', to_bitmap(3)) ) t(k, b) GROUP BY k; -- x | 2 -- y | 1

Related Documentation

• BITMAP_UNION — returns a BITMAP object instead of the cardinality
• BITMAP_AGG