BITMAP_UNION
Description
Calculates the union of input Bitmaps and returns a new Bitmap.
Syntax
BITMAP_UNION(<expr>)
Arguments
Argument | Description |
---|---|
<expr> | Data type supporting Bitmap |
Return Value
Returns a value of Bitmap type. If there is no valid data in the group, returns an empty Bitmap.
Example
-- setup
CREATE TABLE pv_bitmap (
dt INT,
page INT,
user_id BITMAP
) DISTRIBUTED BY HASH(dt) BUCKETS 1
PROPERTIES ("replication_num" = "1");
INSERT INTO pv_bitmap VALUES
(1, 100, to_bitmap(100)),
(1, 100, to_bitmap(200)),
(1, 100, to_bitmap(300)),
(2, 200, to_bitmap(300));
select bitmap_to_string(bitmap_union(user_id)) from pv_bitmap;
+-----------------------------------------+
| bitmap_to_string(bitmap_union(user_id)) |
+-----------------------------------------+
| 100,200,300 |
+-----------------------------------------+
select bitmap_to_string(bitmap_union(user_id)) from pv_bitmap where user_id is null;
+-----------------------------------------+
| bitmap_to_string(bitmap_union(user_id)) |
+-----------------------------------------+
| |
+-----------------------------------------+