Schema

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

Showing Schemas

The SHOW NODE SCHEMA and SHOW EDGE SCHEMA statements retrieve information about node and edge schemas of the current graph.

SHOW NODE SCHEMA

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

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 for each schema. Each edge schema is counted based on the distinct combinations of the start and end node schemas it connects.

Creating Schemas

The ALTER GRAPH statement can be used to add node and edge schemas to a graph.

<alter graph statement> ::= 
  "ALTER GRAPH" <graph name> { <add node schemas> | <add edge schemas> }

<add node schemas> ::=
  "ADD NODE" "{" <add node schema> [ { "," <add node schema> }... ] "}"

<add node schema> ::=
  <schema name> "(" [ <property types> ] ")"

<add edge schemas> ::=
  "ADD EDGE" "{" <add edge schema> [ { "," <add edge schema> }... ] "}"

<add edge schema> ::=
  <schema name> "()-[" [ <property types> ] "]->()"

<property types> ::= 
  "{" <property type> [ { "," <property type> }... ] "}"

<property type> ::= 
  <property name> <property value type> [ <property description> ]

Details

Each node or edge schema is defined by the following:

• Schema name. See naming conventions.
• Associated properties (Optional). Each property is defined by the following:
  • Property name. See naming conventions.
  • Property value type. See all property value types.
  • Property description (Optional): Description of the property.

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 datetime}]->(),
  StudyAt ()-[]->()
}

Renaming Schemas

The ALTER NODE or ALTER EDGE statement can be used to rename 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

Altering Schema Descriptions

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

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

ALTER NODE User COMMENT "Users from self-registration"

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

ALTER EDGE Follows 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