Defining a Graph Schema

A graph schema is the formal dictionary that defines your entities (vertices) and relationships (edges).

1. Defining Vertices

Use CREATE VERTEX to define a global entity.

Syntax Options

1. Using PRIMARY_ID (Standard):

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   CREATE VERTEX Person (PRIMARY_ID user_id STRING, name STRING, age INT)

   Note: Use WITH primary_id_as_attribute="true" if you need to access the ID like a regular attribute in queries.

2. Using PRIMARY KEY:

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   CREATE VERTEX Book (id UINT PRIMARY KEY, title STRING)

3. Composite Keys:

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   CREATE VERTEX Movie (id UINT, title STRING, year UINT, PRIMARY KEY (title, year, id))

2. Defining Edges

Edges connect a source vertex to a target vertex.

Undirected Edges (Bidirectional)

Useful for friendships or peer relationships.

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CREATE UNDIRECTED EDGE Friend_Of (FROM Person, TO Person, on_date DATETIME)

Directed Edges (One-way)

Useful for hierarchical or flow relationships.

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CREATE DIRECTED EDGE Sequel_Of (FROM Book, TO Book) WITH REVERSE_EDGE="Preceded_By"

Note: WITH REVERSE_EDGE automatically creates a corresponding edge in the opposite direction, which is essential for "backward" traversal performance.

Edge Discriminators

To allow multiple instances of the same edge type between two vertices, use a DISCRIMINATOR:

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CREATE DIRECTED EDGE Study_At (FROM Person, TO University, DISCRIMINATOR(class_year INT), major STRING)

3. Defining the Graph

The CREATE GRAPH statement groups vertex and edge types into a usable database domain.

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# Include specific types
CREATE GRAPH MySocialGraph (Person, Friend_Of)

# Include ALL defined types
CREATE GRAPH EverythingGraph (*)

Working with Graphs

• USE GRAPH <name>: Set the active graph for your session.
• DROP GRAPH <name>: Deletes the graph definition and all local types (global types remain).
• DROP ALL: Non-reversible command that wipes the entire graph store and catalog.

Global vs. Local Scope

• Global Types: Created in global mode. Shared across multiple graphs. Any change to a global vertex is seen by all graphs using it.
• Local Types: Created within a specific graph's schema change job. Visible only to that graph.