{ “title”: “SUM_MAP”, “language”: “en”, “description”: “The SUM_MAP function aggregates MAP values by key and returns the sum of values for each key.” }

Description

The SUM_MAP function aggregates MAP values by key and returns a MAP that contains the sum of non-NULL values for each key.

Usage Notes

The order of entries in the returned MAP is not guaranteed. Use map_keys, map_values, array_sort, and array_sortby when stable output order is required. A NULL key is aggregated as a regular key; all NULL keys belong to the same result entry.

Syntax

SUM_MAP(<map_expr>)

Parameters

ParameterDescription
<map_expr>A MAP expression. The MAP value type must be numeric.

Return Value

Returns a MAP with the same key type as <map_expr>. For integer-like, Boolean, and NULL value types, the returned value type is BIGINT. For Float and Double value types, the returned value type is DOUBLE. For Decimal value types, the returned value type is a Decimal type with the maximum supported precision and the same scale. For LargeInt value types, the returned value type is LargeInt.

If there is no valid input row in the group, returns an empty MAP. If a key appears but all values for that key are NULL, the value for that key is NULL.

Example

-- setup
CREATE TABLE map_agg_example (
    id INT,
    m MAP<INT, INT>,
    md MAP<STRING, DECIMAL(10, 2)>
) DISTRIBUTED BY HASH(id) BUCKETS 1
PROPERTIES ("replication_num" = "1");

INSERT INTO map_agg_example VALUES
    (1, MAP(1, 10, 2, 20), MAP('a', 1.20, 'b', 2.30)),
    (1, MAP(2, 5, 3, 30), MAP('b', 3.70, 'c', 4.00)),
    (2, MAP(1, 7, 4, NULL), MAP('a', NULL, 'c', 5.50)),
    (2, CAST(MAP() AS MAP<INT, INT>), CAST(MAP() AS MAP<STRING, DECIMAL(10, 2)>));

Query OK

SELECT id,
       array_sort(map_keys(result)) AS keys,
       array_sortby(map_values(result), map_keys(result)) AS values
FROM (
    SELECT id, SUM_MAP(m) AS result
    FROM map_agg_example
    GROUP BY id
) t
ORDER BY id;

+------+-----------+--------------+
| id   | keys      | values       |
+------+-----------+--------------+
|    1 | [1, 2, 3] | [10, 25, 30] |
|    2 | [1, 4]    | [7, null]    |
+------+-----------+--------------+

SELECT array_sort(map_keys(result)) AS keys,
       array_sortby(map_values(result), map_keys(result)) AS values
FROM (
    SELECT SUM_MAP(md) AS result
    FROM map_agg_example
) t;

+-----------------+--------------------+
| keys            | values             |
+-----------------+--------------------+
| ["a", "b", "c"] | [1.20, 6.00, 9.50] |
+-----------------+--------------------+

SELECT array_sort(map_keys(result)) AS keys,
       array_sortby(map_values(result), map_keys(result)) AS values
FROM (
    SELECT SUM_MAP(m) AS result
    FROM map_agg_example
    WHERE id = 100
) t;

+------+--------+
| keys | values |
+------+--------+
| []   | []     |
+------+--------+