Returns all keys in Map a as an array.
Syntax
array<K> map_keys(map<K, V> <a>)Parameters
a: required. This parameter specifies a map. K and V in map<K, V> specify the keys and values of a map.
Return value
A value of the ARRAY type is returned. If the input map is null, null is returned.
Examples
Return all keys in a map based on the data in the t_table_map table that contains the c1 (BIGINT) and t_map (MAP<STRING,BIGINT>) columns. Data in the table:
+------------+-------+
| c1 | t_map |
+------------+-------+
| 1000 | {k11:86, k21:15} |
| 1001 | {k12:97, k22:2} |
| 1002 | {k13:99, k23:1} |
+------------+-------+Sample statement:
-- Return keys in the t_map column as an array.
select c1, map_keys(t_map) from t_table_map;
-- The following result is returned:
+------------+------+
| c1 | _c1 |
+------------+------+
| 1000 | [k11, k21] |
| 1001 | [k12, k22] |
| 1002 | [k13, k23] |
+------------+------+Related functions
MAP_KEYS is a complex type function. For more information about the functions that are used to process data of complex data types, such as ARRAY, MAP, STRUCT, and JSON, see Complex type functions.