mysql> create table array_type_table(k1 INT, k2 Array<STRING>) duplicate key (k1)
    -> distributed by hash(k1) buckets 1 properties('replication_num' = '1');
mysql> insert into array_type_table values (0, []), ("1", [NULL]), ("2", ["1", "2", "3"]), ("3", ["1", NULL, "3"]), ("4", NULL);
mysql> set enable_vectorized_engine = true;    # enable vectorized engine
mysql> select k2, array_enumerate(k2) from array_type_table;
+------------------+-----------------------+
| k2               | array_enumerate(`k2`) |
+------------------+-----------------------+
| []               | []                    |
| [NULL]           | [1]                   |
| ['1', '2', '3']  | [1, 2, 3]             |
| ['1', NULL, '3'] | [1, 2, 3]             |
| NULL             | NULL                  |
+------------------+-----------------------+
5 rows in set (0.01 sec)

ARRAY,ENUMERATE,ARRAY_ENUMERATE