Composite Query

Overview

A composite query combines the result sets of multiple linear queries using the following query conjunctions:

Details

• UNION, EXCEPT, and INTERSECT perform deduplication on the final result set by default.
• Different query conjunctions can be used within a composite query statement.

To combine the result sets of multiple linear queries, the RETURN statements in all linear queries include the same number of return items, in the same order and with the same names. Each return item with the same name must also have the same type.

Example Graph

GQL
INSERT (rowlock:User {_id:'U01', name:'rowlock'}),
       (brainy:User {_id:'U02', name:'Brainy'}),
       (purplechalk:User {_id:'U03', name:'purplechalk'}),
       (mochaeach:User {_id:'U04', name:'mochaeach'}),
       (lionbower:User {_id:'U05', name:'lionbower'}),
       (c01:Club {_id:'C01'}),
       (c02:Club {_id:'C02'}),
       (rowlock)-[:Follows]->(brainy),
       (brainy)-[:Follows]->(rowlock),
       (mochaeach)-[:Follows]->(brainy),
       (brainy)-[:Follows]->(purplechalk),
       (purplechalk)-[:Follows]->(brainy),
       (brainy)-[:Joins]->(c01),
       (lionbower)-[:Joins]->(c01),
       (mochaeach)-[:Joins]->(c02)

UNION

GQL
MATCH (n:Club) RETURN n
UNION
MATCH (n) RETURN n

Result:

JSON
[
  {"id": "C02", "labels": ["Club"], "properties": {}},
  {"id": "C01", "labels": ["Club"], "properties": {}},
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}},
  {"id": "U02", "labels": ["User"], "properties": {"name": "Brainy"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U04", "labels": ["User"], "properties": {"name": "mochaeach"}},
  {"id": "U05", "labels": ["User"], "properties": {"name": "lionbower"}}
]

UNION ALL

GQL
MATCH (n:Club) RETURN n
UNION ALL
MATCH (n) RETURN n

Result:

JSON
[
  {"id": "C02", "labels": ["Club"], "properties": {}},
  {"id": "C01", "labels": ["Club"], "properties": {}},
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}},
  {"id": "U02", "labels": ["User"], "properties": {"name": "Brainy"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U04", "labels": ["User"], "properties": {"name": "mochaeach"}},
  {"id": "U05", "labels": ["User"], "properties": {"name": "lionbower"}},
  {"id": "C02", "labels": ["Club"], "properties": {}},
  {"id": "C01", "labels": ["Club"], "properties": {}}
]

EXCEPT

GQL
MATCH ({_id: "U02"})-(n) RETURN n
EXCEPT
MATCH ({_id: "U05"})-(n) RETURN n

Result:

JSON
[
  {"id": "U04", "labels": ["User"], "properties": {"name": "mochaeach"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}}
]

EXCEPT ALL

GQL
MATCH ({_id: "U02"})-(n) RETURN n
EXCEPT ALL
MATCH ({_id: "U05"})-(n) RETURN n

Result:

JSON
[
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U04", "labels": ["User"], "properties": {"name": "mochaeach"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}}
]

INTERSECT

GQL
MATCH ({_id: "U01"})-(u:User) RETURN u
INTERSECT
MATCH ({_id: "U03"})-(u:User) RETURN u

Result:

JSON
[
  {"id": "U02", "labels": ["User"], "properties": {"name": "Brainy"}}
]

INTERSECT ALL

GQL
MATCH ({_id: "U01"})-(u:User) RETURN u
INTERSECT ALL
MATCH ({_id: "U03"})-(u:User) RETURN u

Result:

JSON
[
  {"id": "U02", "labels": ["User"], "properties": {"name": "Brainy"}},
  {"id": "U02", "labels": ["User"], "properties": {"name": "Brainy"}}
]

OTHERWISE

GQL
MATCH ({_id: "U04"})<-[]-(u:User) RETURN u
OTHERWISE
MATCH ({_id: "U02"})<-[]-(u:User) RETURN u

Result:

JSON
[
  {"id": "U01", "labels": ["User"], "properties": {"name": "rowlock"}},
  {"id": "U03", "labels": ["User"], "properties": {"name": "purplechalk"}},
  {"id": "U04", "labels": ["User"], "properties": {"name": "mochaeach"}}
]

In this example, the result set of the first linear query returns a null value due to the usage of OPTIONAL:

GQL
OPTIONAL MATCH ({_id: "U04"})<-[]-(u:User) RETURN u
OTHERWISE
MATCH ({_id: "U02"})<-[]-(u:User) RETURN u

Result:

Renaming Return Items

You may use the AS keyword to rename return items to ensure that the results of linear queries can be combined.

GQL
MATCH ({_id: "C01"})<-(u) RETURN u.name, 1 AS Club
UNION
MATCH ({_id: "C02"})<-(u) RETURN u.name, 2 AS Club

Result:

Using Different Query Conjunctions

GQL
MATCH (n:Club) RETURN n._id
OTHERWISE
MATCH (n) RETURN n._id
UNION ALL
MATCH (n)-[]->(:Club) RETURN n._id

Result: