size (cardinality)

description

Syntax

BIGINT size(ARRAY<T> arr) 
BIGINT cardinality(ARRAY<T> arr)

Returns the size of the array, returns NULL for NULL input.

notice

Only supported in vectorized engine

example

mysql> set enable_vectorized_engine=true;
mysql> select k1,k2,size(k2) from array_test;
+------+-----------+------------+
| k1   | k2        | size(`k2`) |
+------+-----------+------------+
|    1 | [1, 2, 3] |          3 |
|    2 | []        |          0 |
|    3 | NULL      |       NULL |
+------+-----------+------------+
mysql> select k1,k2,cardinality(k2) from array_test;
+------+-----------+-------------------+
| k1   | k2        | cardinality(`k2`) |
+------+-----------+-------------------+
|    1 | [1, 2, 3] |                 3 |
|    2 | []        |                 0 |
|    3 | NULL      |              NULL |
+------+-----------+-------------------+

keywords

SIZE, CARDINALITY