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

# SetAgg

A SetAgg aggregator value variable (`SetAgg<T>`) aggregates all inputs into a set that contains only unique values, where `T` represents the data type of the input values. To aggregate a list of input values with duplicates, see [ListAgg](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/variable-definition/agg/list_agg/).

## Declaration syntax

diagramsource

 set_agg_declaration  

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

````

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 must not be specified 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

````
SetAgg<T> -> LIST<T>

````

The return type is `LIST<T>`, with unique elements of the same type as the type `T` specified during declaration.

## Member functions

This section introduces the member functions supported by `SetAgg<T>`.

### size()

Returns the number of unique elements in the set held by a SetAgg aggregator value variable.

#### Function signature

````
size() -> UINT64

````

### clear()

Removes all elements from the set held by a SetAgg aggregator value variable.

#### Function signature

````
clear() -> VOID

````

### contains_key()

Returns true if the specified value exists in the set held by a SetAgg aggregator value variable; otherwise, it returns false.

#### Function signature

````
contains_key(value: T) -> BOOL

````

## 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 SetAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  VALUE global_set_1 SetAgg<INT>
  VALUE global_set_2 SetAgg<INT>
  SET @global_set_1 += 3    // set: {3}
  SET @global_set_1 += 7    // set: {3, 7}  
  SET @global_set_1 += 3    // set: {3, 7} (duplicate ignored)
  SET @global_set_1 += 5    // set: {3, 7, 5}
  LOG_INFO("@global_set_1: ", @global_set_1)

  // Assignment from empty LIST
  SET @global_set_1 = []  // Clear the set
  LOG_INFO("Set from empty LIST:", @global_set_1)  // output: []

  // Assignment from a LIST 
  SET @global_set_1 = [1, 2, 2, 3, 1, 4]  // set: {1, 2, 3, 4}
  LOG_INFO("Set from LIST assignment: ", @global_set_1)

  SET @global_set_2 += 3  // global_set_2: {3}
  SET @global_set_2 += 4  // global_set_2: {3,4}
  LOG_INFO("@global_set_2: ", @global_set_2)

  // Assignment from another SetAgg
  SET @global_set_1 = @global_set_2        // global_set_1: {3,4}
  LOG_INFO("After assignment from set_2: ", @global_set_1)

  // Aggregation from another SetAgg
  SET @global_set_1 += @global_set_2       // global_set_1: {3,4}
  LOG_INFO("After aggregation from set_2: ", @global_set_1)

  // Member functions
  SET @global_set_2.clear()  // Clear the set 
  LOG_INFO("Clear the set: ", @global_set_2)      // Output: []
  LOG_INFO("Size: ", @global_set_1.size())      // Output: 4
  LOG_INFO("Contains 4: ", @global_set_1.contains_key(4))      // Output: true
  LOG_INFO("Contains 100: ", @global_set_1.contains_key(100))      // Output: false
}
'''

````

Return:

````
Log:
2025-08-21T02:18:53.175811 INFO  - @global_set_1: [5,7,3]
2025-08-21T02:18:53.176426 INFO  - Set from empty LIST:[]
2025-08-21T02:18:53.176812 INFO  - Set from LIST assignment: [4,3,2,1]
2025-08-21T02:18:53.177273 INFO  - @global_set_2: [4,3]
2025-08-21T02:18:53.177556 INFO  - After assignment from set_2: [3,4]
2025-08-21T02:18:53.177808 INFO  - After aggregation from set_2: [3,4]
2025-08-21T02:18:53.178056 INFO  - Clear the set: []
2025-08-21T02:18:53.178199 INFO  - Size: 2
2025-08-21T02:18:53.178400 INFO  - Contains 4: true
2025-08-21T02:18:53.178600 INFO  - Contains 100: false

````

### Node-attached SetAgg aggregator value variables

````
'''
USE #movie_temporary_graph {
  NODE VALUE node_set SetAgg<DOUBLE>
  MATCH (a@User WHERE a.id IN [1,3,4])-[w@Watch]->(b@Movie)
  PER PATH {
    // For each matched path, add the movie ID to the corresponding user's set
    SET a.@node_set += b.id
  }
  PER NODE (a) {
    LOG_INFO("a.id: ", a.id, " a.@node_set: ", a.@node_set)
  }
}
'''

````

In the preceding example, a node-attached SetAgg aggregator value variable `node_set` of type `SetAgg<DOUBLE>` is declared to hold a set of unique movie IDs for each user.

Return:

````
Log:
2025-08-12T09:05:22.315257 INFO  - a.id: 1 a.@node_set: [10,104,11,497,252,601,100,651,473]
2025-08-12T09:05:22.315257 INFO  - a.id: 3 a.@node_set: [152,473]
2025-08-12T09:05:22.315257 INFO  - a.id: 4 a.@node_set: [346,99,648,144,637,146,671,10,104,11,252,473]

````