Design a schema

To operate graph data in Nebula Graph with Studio, you must have a graph schema. This article introduces how to design a graph schema for Nebula Graph.

A graph schema for Nebula Graph must have these essential elements:

• Tags (namely vertex types) and their properties.
• Edge types and their properties

In this article, the Social Network: MOOC User Action Dataset and 97 distinct course names are used to introduce how to design a schema.

This table gives all the essential elements of the schema.

Element	Name	Property name (Data type)	Description
Tag	user	userId (int). The userId values are used to generate VIDs of user vertices.	Represents users of the specified MOOC platform.
Tag	course	courseId (int) and courseName (string). The courseName values are processed by the Hash() function to generate VIDs of course vertices. In Nebula Graph, VIDs must be distinct through a graph space. But in the source dataset, some courseId values are duplicate with some userId values, so the courseId values cannot be used to generate the VIDs of course vertices.	Represents the courses on the specified MOOC platform.
Edge type	action	- actionId (int) - duration (double): Represents the duration of an action measured in seconds from the beginning. Its values are equal to the timestamp values in the data source. - label (bool): Represents whether a user drops out after an action. TRUE indicates a drop-out action, FALSE otherwise. - feature0 (double) - feature1 (double) - feature2 (double) - feature3 (double)	Represents actions taken by users on the specified MOOC platform. An action links a user and a course and the direction is from a user to a course. It has four features.

This figure shows the relationship (action) between a user and a course on the MOOC platform.