TRANSFORM_VALUES

SinceVersion dev

Description

Applies a lambda expression to every entry in a map and constructs a new map with the original keys and the transformed values. The lambda receives the key and value of each entry.

Syntax

TRANSFORM_VALUES((<key>, <value>) -> <new_value>, <map>)

Parameters

Parameter	Description
<key>	The lambda parameter representing the key of a map entry.
<value>	The lambda parameter representing the value of a map entry.
<new_value>	An expression that produces the value in the returned map.
<map>	A MAP<K, V> expression.

Return Value

Returns a MAP<K, V2>, where V2 is the type returned by the lambda.

• The keys in the input map are retained unchanged.
• If <map> is empty, returns an empty map.
• If <map> is NULL, returns NULL.
• A NULL value returned by the lambda is retained.

Examples

SELECT transform_values((k, v) -> v + k, map(1, 10, 2, 20)) AS result;

+--------------+
| result       |
+--------------+
| {1:11, 2:22} |
+--------------+

SELECT transform_values(
    (k, v) -> if(k = 1, CAST(NULL AS INT), v),
    map(1, 10, 2, 20)) AS result;

+----------------+
| result         |
+----------------+
| {1:null, 2:20} |
+----------------+

SELECT transform_values((k, v) -> v, CAST(NULL AS MAP<INT, INT>)) AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+