MAP_FROM_ENTRIES

Description

Constructs a MAP<K, V> from an array whose elements are two-field STRUCTs. The first field is used as the key and the second field as the value.

note

This function is supported since Apache Doris 4.2.

Syntax

MAP_FROM_ENTRIES(<entries>)

Parameters

Parameter	Description
<entries>	An ARRAY<STRUCT<K, V>>. Each STRUCT must contain exactly two fields. The array can be NULL, and the two fields inside a STRUCT can be NULL, but a STRUCT array element itself cannot be NULL. K must be a type supported by MAP keys.

Return Value

Returns a MAP<K, V>.

• If <entries> is NULL, returns NULL.
• NULL fields inside a non-NULL STRUCT are retained as NULL keys or values.
• If a STRUCT array element itself is NULL, a runtime error is reported.
• If the input is not an array of STRUCTs, or a STRUCT has fewer or more than two fields, an analysis error is reported.
• If K is not a type supported by MAP keys, an analysis error is reported.
• If a key occurs more than once, the value from the last occurrence is retained.

Examples

SELECT map_from_entries(array(struct(1, 10), struct(2, 20))) AS result;

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

SELECT map_from_entries(array(struct(1, 10), struct(1, 20))) AS result;

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

SELECT map_from_entries(CAST(NULL AS ARRAY<STRUCT<k:INT,v:INT>>));

+------------------------------------------------------------+
| map_from_entries(CAST(NULL AS ARRAY<STRUCT<k:INT,v:INT>>)) |
+------------------------------------------------------------+
| NULL                                                       |
+------------------------------------------------------------+

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

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

The following example fails because the array contains a NULL STRUCT element:

SELECT map_from_entries(array(CAST(NULL AS STRUCT<k:INT,v:INT>)));

ERROR 1105 (HY000): Map entry of function map_from_entries cannot be null

The following example fails during analysis because the STRUCT has three fields:

SELECT map_from_entries(array(struct(1, 2, 3)));

ERROR 1105 (HY000): map_from_entries requires an array of structs with exactly two fields