Subgraph definition in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a subgraph in GraphQL?

A subgraph is a smaller part of a larger GraphQL graph. It defines a set of types and fields that focus on a specific domain or service.

beginner

What does a subgraph definition usually include?

It includes the schema with types, queries, mutations, and sometimes directives that describe the data and operations for that subgraph.

intermediate

Why do we use subgraphs in a GraphQL architecture?

Subgraphs help split a big graph into smaller, manageable parts. This makes development easier and allows teams to work independently on different domains.

intermediate

How does a subgraph relate to a federated GraphQL gateway?

A federated gateway combines multiple subgraphs into one unified graph. Each subgraph provides part of the overall schema that the gateway merges.

advanced

What is the role of the @key directive in a subgraph definition?

The @key directive marks a field or set of fields as a unique identifier for an entity. It helps the gateway know how to reference and join data across subgraphs.

What does a subgraph in GraphQL represent?

A A database table

B A frontend UI component

C A part of the overall graph focusing on a specific domain

D A GraphQL query operation

A subgraph is a focused part of the overall graph, representing a domain or service.

Which directive is commonly used in subgraph definitions to identify entities uniquely?

A @key

B @entity

C @unique

D @id

The @key directive marks fields as unique identifiers for entities in subgraphs.

What is the main purpose of splitting a GraphQL schema into subgraphs?

A To allow multiple teams to work independently on different parts

B To reduce the number of queries sent

C To improve query speed by caching

D To avoid using GraphQL federation

Splitting into subgraphs helps teams work independently and manage complexity.

In a federated GraphQL setup, what combines the subgraphs into one schema?

A GraphQL client

B Federated gateway

C Database engine

D GraphQL server

The federated gateway merges subgraphs into a single unified schema.

Which of the following is NOT typically part of a subgraph definition?

A Directives

B Resolvers

C Type definitions

D UI components

UI components are not part of a subgraph definition; subgraphs define schema and resolvers.

Explain what a subgraph definition is and why it is useful in GraphQL.

Think about how big projects can be divided into smaller pieces.

Describe the role of the @key directive in a subgraph definition and how it helps federation.

Focus on how different subgraphs connect their data.