BITMAP_UNION

Overview

Performs a union aggregation over a column of BITMAP objects and returns the merged BITMAP. Commonly used together with BITMAP_TO_STRING or BITMAP_COUNT to inspect the result.

Syntax

BITMAP_UNION(<bitmap_col>)

Parameters

• <bitmap_col>: A column of BITMAP type.

Examples

-- Merge multiple BITMAPs and inspect the result SELECT bitmap_to_string(bitmap_union(b)) FROM ( VALUES (to_bitmap(1)), (to_bitmap(2)), (to_bitmap(1)) ) t(b); -- 1,2 -- With GROUP BY SELECT k, bitmap_to_string(bitmap_union(b)) FROM ( VALUES ('x', to_bitmap(1)), ('x', to_bitmap(2)), ('y', to_bitmap(3)) ) t(k, b) GROUP BY k; -- x | 1,2 -- y | 3

Related Documentation

• BITMAP_UNION_COUNT — returns the cardinality of the union directly
• BITMAP_AGG — aggregates an integer column into a BITMAP
• TO_BITMAP