Schema

This page introduces statements for managing node and edge schemas in a graph.

Showing Schemas

Retrieve node schemas of the current graph:

SHOW NODE SCHEMA

Retrieve edge schemas of the current graph:

SHOW EDGE SCHEMA

The information about schemas is organized into different tables:

• Node schemas: Stored in _nodeSchema (all schemas) and _nodeSchema_shard_<id> (schemas with data stored in one shard).
• Edge schemas: Stored in _edgeSchema (all schemas) and _edgeSchema_shard_<id> (schemas with data stored in one shard).

Ultipa Manager has been configured to display only the _nodeSchema and _edgeSchema tables.

Each table includes the following fields:

There is another table, _graphCount, which provides an overview of the number of nodes and edges of each schema. Each edge schema is counted based on the distinct combinations of the start and end node schemas it connects.

Creating Schemas

You can use the ALTER GRAPH statement to add node and edge schemas to a graph.

To add node schemas User, Club, and School to the graph g1:

ALTER GRAPH g1 ADD NODE {
  User ({username STRING COMMENT "Username, cannot be null", gender STRING}),
  Club ({name STRING, since UINT32}),
  School ()
}

To add edge schemas Follows and StudyAt to the graph g1:

ALTER GRAPH g1 ADD EDGE {
  Follows ()-[{createdOn DATE}]->(),
  StudyAt ()-[]->()
}

References:

• Naming conventions for schemas
• Naming conventions for properties
• All supported property value types

Altering Schema Name and Comment

The ALTER NODE or ALTER EDGE statement can be used to alter the name and comment of a node or edge schema in the current graph.

To rename the node schema School to University in the current graph:

ALTER NODE School RENAME TO University

To rename the edge schema Follows to Follow in the current graph:

ALTER EDGE Follows RENAME TO Follow

To update the comment of the node schema User in the current graph:

ALTER NODE User COMMENT "Self-registration"

To update the comment of the edge schema Follows in the current graph:

ALTER EDGE Follows COMMENT "From user to user"

You can perform both operations—renaming a schema and updating its comment—in a single ALTER NODE or ALTER EDGE statement:

ALTER NODE User RENAME TO User_s2 COMMENT "Self-registration"

ALTER EDGE Follows RENAME TO Follow COMMENT "From user to user"

Dropping Schemas

The ALTER GRAPH statement can be used to delete node and edge schemas from a graph. Dropping a node or edge schema deletes the schema along with the nodes or edges belonging to it. Note that the deletion of a node leads to the removal of all edges that are connected to it. The two default schemas cannot be dropped.

The schema dropping operation runs as a job, you may run SHOW JOB <id?> afterward to verify its completion.

To drop a node schema User from the graph g1:

ALTER GRAPH g1 DROP NODE User 

To drop edge schemas Follows and StudyAt from the graph g1:

ALTER GRAPH g1 DROP EDGE Follows, StudyAt