---

{ “title”: “BITMAP_UNION_COUNT”, “language”: “en”, “description”: “Computes the union of input Bitmaps and returns their cardinality.” }

Description

Computes the union of input Bitmaps and returns their cardinality.

Syntax

BITMAP_UNION_COUNT(<expr>)

Parameters

Parameter	Description
<expr>	Supported data types of BITMAP

Return Value

Returns the size of the Bitmap union, that is, the number of elements after deduplication

Example

-- setup
create table pv_bitmap(dt int, page int, user_id bitmap bitmap_union) aggregate key(dt,page) distributed by hash(dt) buckets 1 properties ("replication_num"="1");
insert into pv_bitmap values (1,100,bitmap_from_string('100,200,300')),(2,200,bitmap_from_string('300'));

select dt,page,bitmap_to_string(user_id) from pv_bitmap;

+------+------+---------------------------+
| dt   | page | bitmap_to_string(user_id) |
+------+------+---------------------------+
|    1 | 100  | 100,200,300               |
|    2 | 200  | 300                       |
+------+------+---------------------------+

Calculate the deduplication value of user_id:

select bitmap_union_count(user_id) from pv_bitmap;

+-------------------------------------+
| bitmap_count(bitmap_union(user_id)) |
+-------------------------------------+
|                                   3 |
+-------------------------------------+