Edge Table Management

This document describes the commands for managing edge tables in the graph database.

Overview

Edge tables define the relationships between vertex tables in a graph database. Each edge represents a connection between two vertices, with optional properties stored as columns.

Create Edge Table

Key Features:

• Define directed or undirected edges (currently only support directed edges).
• Specify source and target vertex tables
• Add properties as columns with data types
• Optional reverse edge creation
• Control edge uniqueness constraints

Syntax

CREATE DIRECTED | UNDIRECTED EDGE <edge_table_name>
(
    FROM <source_vertex_table_name> 
    TO <target_vertex_table_name>,
    <column_name> <data_type> [NOT NULL | NULL ],
    <column_name> <data_type> ...
)
[ WITH REVERSE EDGE <reverse_edge_table_name> ]
[ EDGE_UNIQUENESS = SINGLE | MULTIPLE ]

Currently, we only allow following data types as edge properties:

• BOOLEAN
• BIGINT
• DOUBLE
• VARCHAR
• DATE
• DATETIME
• TIME
• TIMESTAMP

EDGE_UNIQUENESS:

• SINGLE: There will be at most one edge with value (src, dst).
• MULTIPLE: Allow multiple edges with the same (src, dst).

Example

Create a edge table named Buy, with sourcee vertex table User and target vertex table Item. And edge table has three columns, namely col1, col2 and col3. And requires col1 has an NOT NULL constraint.

And also create an edge table named rBuy which store the reverse direction of Buy.

CREATE DIRECTED EDGE Buy
(
  FROM User
  TO Item,
  col1 INTEGER NOT NULL,
  col2 VARCHAR,
  col3 VARCHAR
)
WITH REVERSE EDGE rBuy.

Drop Edge Table

Drop an edge table with given name.

Syntax

DROP EDGE <edge_table_name>

Example

DROP EDGE Buy

Describe Edge Table

Describe meta information about an edge table

Syntax

DESCRIBE EDGE <edge_table_name>

Example

DESCRIBE EDGE Buy

List Edge Tables

List all edge table names.

Syntax

LIST EDGE

Rename Columm Name

Rename table column if both table and column exists.

ALTER TABLE [IF EXISTS] <table_name>
RENAME COLUMN [IF EXISTS] <column_name> TO <new_column_name>

Example

ALTER TABLE KNOWS RENAME COLUMN age To new_age