Schema

Overview

In Ultipa, a schema represents a node or edge type. Schemas are integral to the graph structure and must be defined before any node or edge data can be inserted. Each node or edge is assigned to exactly one schema.

In UQL, the operator @ denotes a schema. The expression @<schema> specifies a particular schema, such as @Account.

Schema in UQL analogous a label in GQL.

Default Schemas

Each graphset comes with a built-in node schema and edge schema, both named default. The two default schemas are available for unrestricted use but cannot be deleted. Additionally, their names and descriptions cannot be altered.

Showing Schemas

To retrieve information about schemas in the current graphset:

// Shows all schemas 
show().schema()

// Shows all node schemas 
show().node_schema()

// Shows the specified node schema
show().node_schema(@user)

// Shows all edge schemas 
show().edge_schema()

// Shows the specified edge schema
show().edge_schema(@transfers)

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

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

You can create one or more schemas using a single create() statement. Each schema is defined by calling a node_schema() or edge_schema() method as part of a method chain.

create()
  .node_schema("<schemaName>", "<schemaDesc?>")
  .edge_schema("<schemaName>", "<schemaDesc?>")
  ...

To create a node schema:

create().node_schema("user", "Self-registeration")

To create an edge schema:

create().edge_schema("likes")

To create multiple schemas:

create()
  .node_schema("user", "Self-registeration")
  .node_schema("movie")
  .edge_schema("likes")

Altering Name and Description

You can modify the name and description of a schema using the alter().node_schema().set() or alter().edge_schema().set() statement. The two default schemas cannot be altered.

To alter both name and description of the node schema @user:

alter().node_schema(@user).set({name: "User", description: "club users"})

To alter name and remove description of the edge schema @join:

alter().edge_schema(@join).set({name: "joins", description: ""})

To alter name of the node schema @account:

alter().node_schema(@account).set({name: "user"})

To alter description of the edge schema @link:

alter().edge_schema(@link).set({description: "the link between people and event"})

Dropping Schemas

You can drop one or more schemas using a single drop() statement. Each schema is specified by chaining a node_schema() or edge_schema() method. The schema dropping operation runs as a job, you may run show().job(<id?>) afterward to verify its completion.

Dropping a schema deletes both the schema and any nodes or edges that belong to it from the database. 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.

To drop the node schema @user:

drop().node_schema(@user)

To drop the edge schema @likes:

drop().edge_schema(@likes)

To drop multiple schemas:

drop().node_schema(@user).edge_schema(@likes)