---

{ “title”: “BITMAP_UNION”, “language”: “en” }

Description

Calculate the union of input Bitmaps and return a new bitmap

Syntax

BITMAP_UNION(<expr>)

Parameters

Parameter	Description
<expr>	Supported data types of BITMAP

Return Value

The data type of the return value is BITMAP.

Example

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_count(bitmap_union(user_id)) from pv_bitmap;

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

Create table

The aggregation model needs to be used when creating the table. The data type is bitmap and the aggregation function is bitmap_union.

CREATE TABLE `pv_bitmap` (
  `dt` int (11) NULL COMMENT" ",
  `page` varchar (10) NULL COMMENT" ",
  `user_id` bitmap BITMAP_UNION NULL COMMENT" "
) ENGINE = OLAP
AGGREGATE KEY (`dt`,` page`)
COMMENT "OLAP"
DISTRIBUTED BY HASH (`dt`) BUCKETS 2;

Note: When the amount of data is large, it is best to create a corresponding rollup table for high-frequency bitmap_union queries

ALTER TABLE pv_bitmap ADD ROLLUP pv (page, user_id);

Data Load

TO_BITMAP (expr): Convert 0 ~ 18446744073709551615 unsigned bigint to bitmap

BITMAP_EMPTY (): Generate empty bitmap columns, used for insert or import to fill the default value

BITMAP_HASH (expr) or BITMAP_HASH64 (expr): Convert any type of column to a bitmap by hashing

Stream Load

cat data | curl --location-trusted -u user: passwd -T--H "columns: dt, page, user_id, user_id = to_bitmap (user_id)" http: // host: 8410 / api / test / testDb / _stream_load

cat data | curl --location-trusted -u user: passwd -T--H "columns: dt, page, user_id, user_id = bitmap_hash (user_id)" http: // host: 8410 / api / test / testDb / _stream_load

cat data | curl --location-trusted -u user: passwd -T--H "columns: dt, page, user_id, user_id = bitmap_empty ()" http: // host: 8410 / api / test / testDb / _stream_load

Insert Into

id2's column type is bitmap

insert into bitmap_table1 select id, id2 from bitmap_table2;

id2's column type is bitmap

INSERT INTO bitmap_table1 (id, id2) VALUES (1001, to_bitmap (1000)), (1001, to_bitmap (2000));

id2's column type is bitmap

insert into bitmap_table1 select id, bitmap_union (id2) from bitmap_table2 group by id;

id2's column type is int

insert into bitmap_table1 select id, to_bitmap (id2) from table;

id2's column type is String

insert into bitmap_table1 select id, bitmap_hash (id_string) from table;