BITMAP_AGG
description
Syntax
BITMAP_AGG(expr)
聚合 expr 的值（不包括任何空值）得到 bitmap。 expr 的类型需要为 TINYINT,SMALLINT,INT 和 BIGINT 类型。
example
MySQL > select `n_nationkey`, `n_name`, `n_regionkey` from `nation`;
+-------------+----------------+-------------+
| n_nationkey | n_name | n_regionkey |
+-------------+----------------+-------------+
| 0 | ALGERIA | 0 |
| 1 | ARGENTINA | 1 |
| 2 | BRAZIL | 1 |
| 3 | CANADA | 1 |
| 4 | EGYPT | 4 |
| 5 | ETHIOPIA | 0 |
| 6 | FRANCE | 3 |
| 7 | GERMANY | 3 |
| 8 | INDIA | 2 |
| 9 | INDONESIA | 2 |
| 10 | IRAN | 4 |
| 11 | IRAQ | 4 |
| 12 | JAPAN | 2 |
| 13 | JORDAN | 4 |
| 14 | KENYA | 0 |
| 15 | MOROCCO | 0 |
| 16 | MOZAMBIQUE | 0 |
| 17 | PERU | 1 |
| 18 | CHINA | 2 |
| 19 | ROMANIA | 3 |
| 20 | SAUDI ARABIA | 4 |
| 21 | VIETNAM | 2 |
| 22 | RUSSIA | 3 |
| 23 | UNITED KINGDOM | 3 |
| 24 | UNITED STATES | 1 |
+-------------+----------------+-------------+
MySQL > select n_regionkey, bitmap_to_string(bitmap_agg(n_nationkey)) from nation group by n_regionkey;
+-------------+---------------------------------------------+
| n_regionkey | bitmap_to_string(bitmap_agg(`n_nationkey`)) |
+-------------+---------------------------------------------+
| 4 | 4,10,11,13,20 |
| 2 | 8,9,12,18,21 |
| 1 | 1,2,3,17,24 |
| 0 | 0,5,14,15,16 |
| 3 | 6,7,19,22,23 |
+-------------+---------------------------------------------+
MySQL > select bitmap_count(bitmap_agg(n_nationkey)) from nation;
+-----------------------------------------+
| bitmap_count(bitmap_agg(`n_nationkey`)) |
+-----------------------------------------+
| 25 |
+-----------------------------------------+keywords
BITMAP_AGG