Introduction to Apache AGE

What is Apache AGE?

The Apache AGE is a PostgreSQL extension that provides graph database functionality. Therefore, it encompasses the Postgres functionalities while incorporating Cypher for graph management. This unique combination empowers you with access to advanced graph query modeling within the framework of your relational database infrastructure.

Definitions

Vertex (node)
It serves as a container for storing entity-related data, potentially encompassing multiple properties. Notably, each vertex can accommodate a variety of properties, yet it is restricted to possessing a singular label designation.
Edge (relationship)
An edge links nodes in a graph, defining a distinct relationship or interaction with defining attributes. This is vital for navigating intricate interconnections in the graph data model.
Path
The path represents a sequence of connected edges and nodes. It captures the route or journey between entities, enabling the exploration of relationships and patterns within the graph.

Common Clauses using Cypher

CREATE: used to add new nodes and edges to the graph.
DELETE: is used to remove nodes, edges, or entire paths from the graph.
MATCH: used to retrieve data from the graph database. It allows you to specify patterns of nodes and edges, facilitating the discovery of interconnected entities and relationships.
MERGE: allows you to either create new nodes and edges or match and update existing ones based on specified patterns.
REMOVE: used to remove properties from vertex and edges.
RETURN: specify what data you want to retrieve as a result of your query. It allows you to define the attributes or properties of nodes and edges that you're interested in.
SET: used to update properties of nodes or edges within the graph.
WHERE: filters the results of a query based on specified conditions. It helps you narrow down your search and retrieve only the data that meets specific criteria.

Examples

Create a vertex without label and returns it

SELECT * FROM cypher('graph_name', $$ 
    CREATE (v) 
    RETURN v
$$) AS (vertex agtype);

Returns all vertices

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v) 
    RETURN v
$$) AS (vertex agtype);

Create a vertex with a property

SELECT * FROM cypher('graph_name', $$ 
    CREATE (v {property: 'value'})
    RETURN v
$$) AS (vertex agtype);

Return the vertex with the specified value

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v {property: 'value'}) 
    RETURN v
$$) AS (vertex agtype);

Return the vertex with the specified value using WHERE

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v)
    WHERE v.property = 'value'
    RETURN v
$$) AS (vertex agtype);

Delete all vertices

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v) 
    DELETE v
$$) AS (vertex agtype);

Create a vertex with a label and properties

SELECT * FROM cypher('graph_name', $$ 
    CREATE (v:Label {property1: 1, property2: 'value', property3: true}) 
    RETURN v
$$) AS (vertex agtype);

Get all vertices with a specified label

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v:Label) 
    RETURN v
$$) AS (vertex agtype);

Get the vertex with the label and change the value of its property

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v:Label)
    SET v.property1 = 0
    RETURN v
$$) AS (vertex agtype);

Remove the third property

SELECT * FROM cypher('graph_name', $$ 
    MATCH (v:Label)
    REMOVE v.property3
    RETURN v
$$) AS (vertex agtype);

Creating a new vertex and a relationship with our already existing node, returning the created path.

SELECT * FROM cypher('graph_name', $$ 
    MERGE p=(x:Label)-[r:relationship]->(y:newNode)
    RETURN p
$$) AS (path agtype);

References and manual

Apache AGE documentation
Apache AGE repository
Apache AGE website