MAP_FROM_ARRAYS

Description

Constructs a MAP<K, V> from a key array and a value array. Elements at the same position form a key-value pair.

Syntax

MAP_FROM_ARRAYS(<keys>, <values>)

Parameters

Parameter	Description
<keys>	An ARRAY<K>. K must be a type supported by MAP keys. The array and its elements can be NULL.
<values>	An ARRAY<V>. The array and its elements can be NULL. When both arrays are non-NULL, it must have the same number of elements as <keys>.

Return Value

Returns a MAP<K, V>.

• If either input array is NULL, returns NULL.
• NULL elements are retained as NULL keys or values in the result.
• If both arrays are non-NULL but have different lengths, an error is reported. The length of the other array is not checked when either array is NULL.
• If a key occurs more than once, the value from the last occurrence is retained.
• If an argument is not an array, or K is not a type supported by MAP keys, an analysis error is reported.

Examples

SELECT map_from_arrays([1, 2], [10, 20]) AS result;

+--------------+
| result       |
+--------------+
| {1:10, 2:20} |
+--------------+

SELECT map_from_arrays([1, 1], [10, 20]) AS result;

+--------+
| result |
+--------+
| {1:20} |
+--------+

SELECT map_from_arrays(CAST(NULL AS ARRAY<INT>), [10]);

+-------------------------------------------------+
| map_from_arrays(CAST(NULL AS ARRAY<INT>), [10]) |
+-------------------------------------------------+
| NULL                                            |
+-------------------------------------------------+

SELECT map_from_arrays(
    array(CAST(NULL AS INT), 2),
    array(10, CAST(NULL AS INT))) AS result;

+-------------------+
| result            |
+-------------------+
| {null:10, 2:null} |
+-------------------+

SELECT map_from_arrays([1, 2], [10]);

ERROR 1105 (HY000): The key and value array offsets of function map_from_arrays must be identical