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

# MaxAgg

A MaxAgg aggregator value variable (`MaxAgg<T>`) maintains the maximum value among all inputs, where `T` represents the data type of the input values. To maintain the minimum value, see [MinAgg](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/variable-definition/agg/min_agg/).

## Declaration syntax

diagramsource

 max_agg_declaration  

````
max_agg_declaration ::=
'NODE'? 'VALUE' aggregator_value_variable 'MaxAgg' '<' ('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

````
MaxAgg<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 MaxAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  VALUE global_max_int MaxAgg<INT> = 0
  VALUE global_max_double MaxAgg<DOUBLE> = 0.0
  VALUE global_max_string MaxAgg<STRING> = ""

  // INT type: Get the maximum integer value
  SET @global_max_int += 3     // max: 3 (0 < 3, keeps 3)
  SET @global_max_int += 7     // max: 7 (3 < 7, keeps 7)
  SET @global_max_int += 5     // max: 7 (5 < 7, keeps 7)

  // DOUBLE type: Get the maximum floating-point value
  SET @global_max_double += 3.14     // max: 3.14 (0.0 < 3.14, keeps 3.14)
  SET @global_max_double += 7.89     // max: 7.89 (3.14 < 7.89, keeps 7.89)
  SET @global_max_double += 5.5      // max: 7.89 (5.5 < 7.89, keeps 7.89)

  // STRING type: Get the lexicographically largest string by byte comparison
  SET @global_max_string += "apple"     // max: "apple" ("" < "apple", keeps "apple")
  SET @global_max_string += "banana"    // max: "banana" ("apple" < "banana", keeps "banana")
  SET @global_max_string += "cherry"    // max: "cherry" ("banana" < "cherry", keeps "cherry")

  RETURN @global_max_int, @global_max_double, @global_max_string
}
'''

````

Return:

````
+-----------------+--------------------+--------------------+
| @global_max_int | @global_max_double | @global_max_string |
+-----------------+--------------------+--------------------+
| 7               | 7.89               | cherry             |
+-----------------+--------------------+--------------------+

````

### Node-attached MaxAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  NODE VALUE node_max MaxAgg<DOUBLE> = 0
  MATCH (a@User WHERE a.id IN [1,3,4])-[w@Watch]->(b@Movie)
  PER PATH {
    // For each user, track the highest rating on Watch edges
    SET a.@node_max += w.rate
  }
  PER NODE (a) {
    LOG_INFO("a.id: ", a.id, " a.@node_max: ", a.@node_max)
  }
}
'''

````

Return:

````
Log:
2025-08-12T09:02:57.493825 INFO  - a.id: 1 a.@node_max: 5
2025-08-12T09:02:57.493825 INFO  - a.id: 3 a.@node_max: 4.5
2025-08-12T09:02:57.493825 INFO  - a.id: 4 a.@node_max: 5

````