MAP_UNION_SUM - MaxCompute - Alibaba Cloud Documentation Center

Returns a new map that is the union of all input maps. The output map sums the values of the matching keys in all input maps. If the value that corresponds to a key is null, the value is converted into 0.

Usage notes

MaxCompute V2.0 provides additional functions. If the functions that you use involve new data types that are supported in the MaxCompute V2.0 data type edition, you must run a SET command to enable the MaxCompute V2.0 data type edition. The new data types include TINYINT, SMALLINT, INT, FLOAT, VARCHAR, TIMESTAMP, and BINARY.

Session level: To enable the MaxCompute V2.0 data type edition, you must add set odps.sql.type.system.odps2=true; before the SQL statement that you want to execute, and commit and execute them together.
Project level: The project owner can enable the MaxCompute V2.0 data type edition for the project based on the project requirements. The configuration takes effect after 10 to 15 minutes. To enable the MaxCompute V2.0 data type edition at the project level, run the following command:
```
setproject odps.sql.type.system.odps2=true;
```
For more information about setproject, see Project operations. For more information about the precautions that you must take when you enable the MaxCompute V2.0 data type edition at the project level, see Data type editions.

If you use an SQL statement that includes multiple aggregate functions and resources in your project are insufficient, a memory overflow issue may occur. We recommend that you optimize the SQL statement or purchase computing resources based on your business requirements.

Syntax

map<K, V> map_union_sum(map<K, V> input);

Parameters

input: the input maps.

Note

The values in input maps must be of the BIGINT, INT, SMALLINT, TINYINT, FLOAT, DOUBLE, or DECIMAL data type.

Return value

A new map that is the union of all input maps is returned.

Note

The values in the new map are of the BIGINT, DOUBLE, or DECIMAL type.

Examples

select map_union_sum(a) from values
    (map('hi', 2L, 'apple', 3L, 'pie', 1L)), (map('apple', null, 'hi', 4L)), (null) t(a);

The following result is returned:

+----------------------------+
| _c0                        |
+----------------------------+
| {"apple":3,"hi":6,"pie":1} |
+----------------------------+

Related functions

MAP_UNION_SUM is an aggregate function. For more information about the functions that are used to calculate the average value of multiple input records and to aggregate parameters, see Aggregate functions.