Rate Limiting GraphQL APIs by Calculating Query Complexity

GraphQL opens new possibilities for rate limiting. I’ll show you Shopify’s rate limiting system for the GraphQL Admin API and how it addresses some limitations of common methods commonly used in REST APIs.

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Shopify
•
Guilherme Vieira
•7 min read•intermediate•
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•View Original
GraphQLRate LimitingREST API

Overview

The article discusses Shopify's approach to rate limiting GraphQL APIs by calculating query complexity, which enhances API stability and performance. It contrasts traditional request-based models with a calculated query cost method that adapts to the actual data requested, providing a more predictable load on servers.

What You'll Learn

1

How to implement a calculated query cost method for GraphQL APIs

2

Why rate limiting is essential for API stability

3

When to use different query costs for various GraphQL operations

Key Questions Answered

What are the limitations of traditional request-based rate limiting?
Traditional request-based rate limiting has limitations such as clients consuming the same amount of credits regardless of the data needed and not accounting for the different server loads caused by various types of requests. This can lead to inefficiencies and unpredictable server loads.
How does Shopify calculate query costs for GraphQL requests?
Shopify calculates query costs by performing static analysis on the GraphQL query, assigning costs based on the types of data requested. Objects cost one point, connections cost two points plus the number of returned objects, and mutations cost ten points due to their higher server load.
What is the difference between requested and actual query costs?
Requested query cost is calculated before executing the query using static analysis, while actual query cost is determined during execution. If the actual cost is lower than requested, the difference is refunded to the API client, promoting efficient data requests.
How can clients view the calculated query cost in GraphQL responses?
Clients can view the calculated query cost in the API responses through an extension object that includes the query cost. By adding the 'X-GraphQL-Cost-Include-Fields: true' header, they can also receive detailed per-field query costs.

Key Statistics & Figures

Points allocated per second
50 points
Clients receive 50 points per second up to a limit of 1,000 points for making GraphQL requests.
Cost of mutations
10 points
Mutations incur a higher cost due to their potential side effects on databases and server load.

Technologies & Tools

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API
Graphql
Used for implementing the rate limiting model and calculating query costs.

Key Actionable Insights

1
Implementing a calculated query cost model can significantly improve API efficiency.
By adapting the cost of queries based on the actual data requested, developers can encourage clients to make more efficient requests, reducing unnecessary server load and improving overall performance.
2
Understanding the different costs associated with GraphQL operations is crucial for optimizing API usage.
By knowing that mutations cost ten points and connections cost more based on returned objects, developers can design their queries to minimize costs and enhance performance.
3
Utilizing the extension object in GraphQL responses can provide valuable insights into query costs.
This allows developers to adjust their queries based on real-time data, ensuring they remain within acceptable limits while optimizing for performance.

Common Pitfalls

1
Assuming all API requests have the same cost can lead to inefficient usage.
This misconception can result in clients overusing their credits on unnecessary data. Understanding the specific costs associated with different types of requests can help mitigate this issue.