Source: https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/variable-definition/agg/sum_agg/
Documentation version: v5.3.2

# SumAgg

A SumAgg aggregator value variable (`SumAgg<T>`) maintains the aggregated result of all inputs, where `T` represents the data type of the input values. The aggregation behavior depends on the specified data type:

- Numeric types (`INT8`, `INT16`, `INT32`, `INT64`, `FLOAT`, `DOUBLE`): Calculates the mathematical sum of the input values.
- String type (`STRING`): Concatenates the input strings in the order they are processed. Note that there is no implicit delimiter (such as a space) added between the concatenated strings; you must explicitly include delimiters if needed.

## Declaration syntax

diagramsource

 sum_agg_declaration  

````
sum_agg_declaration ::=
  'NODE'? 'VALUE' aggregator_value_variable 'SumAgg' '<' ('INT8'|'INT16'|'INT32'|'INT64'|'FLOAT'|'DOUBLE'|'STRING') '>' '=' value_expression

````

For information about the parameters in the declaration syntax, see [Parameters](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/variable-definition/agg/#parameters).

## Initial value

As indicated in the declaration syntax, an initial value is required during declaration.

## Input type and supported operations

The input type must be `T`, which is specified during declaration.

Both [assignment and aggregation](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/set/) operations are supported.

## Return type

````
SumAgg<T> -> T

````

The return type is the same as the type `T` specified during declaration.

## Examples

The following examples are based on the temporary graph `#movie_temporary_graph` created in [CREATE TEMPORARY GRAPH](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/ddl/graph-projection/create/).

### Global SumAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  VALUE global_sum_int SumAgg<INT> = 0
  VALUE global_sum_double SumAgg<DOUBLE> = 0.0
  VALUE global_sum_string SumAgg<STRING> = ""

  -- INT type: Accumulate integer values
  SET @global_sum_int += 3     // sum: 3 (0 + 3)
  SET @global_sum_int += 4     // sum: 7 (3 + 4)
  SET @global_sum_int += 5     // sum: 12 (7 + 5)

  -- DOUBLE type: Accumulate floating-point values
  SET @global_sum_double += 3.14     // sum: 3.14 (0.0 + 3.14)
  SET @global_sum_double += 4.56     // sum: 7.7 (3.14 + 4.56)
  SET @global_sum_double += 5.3      // sum: 13.0 (7.7 + 5.3)

  -- STRING type: Concatenate strings
  SET @global_sum_string += "Hello"     // sum: "Hello" ("" + "Hello")
  SET @global_sum_string += " "         // sum: "Hello " ("Hello" + " ")
  SET @global_sum_string += "World"     // sum: "Hello World" ("Hello " + "World")

  RETURN @global_sum_int, @global_sum_double, @global_sum_string
}
'''

````

Return:

````
+-----------------+--------------------+--------------------+
| @global_sum_int | @global_sum_double | @global_sum_string |
+-----------------+--------------------+--------------------+
| 12              | 13.0               | Hello World        |
+-----------------+--------------------+--------------------+

````

### Node-attached SumAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  NODE VALUE node_sum SumAgg<INT> = 0
  MATCH (a@Actor WHERE a.id IN [3,4])
  PER NODE (a) {
    SET a.@node_sum += 1     // Increment each actor's sum by 1
  }
  PER NODE (a) {
    LOG_INFO("a.name: ",a.name, " a.id: ",a.id, " a.@node_sum: ",a.@node_sum)
  }
}
'''

````

Return:

````
Log:
2025-08-08T08:29:51.496032 INFO  - a.name: Carrie Fisher a.id: 4 a.@node_sum: 1
2025-08-08T08:29:51.496032 INFO  - a.name: Harrison Ford a.id: 3 a.@node_sum: 1

````