Sankalp Rai Gambhirยท Fullstack Software & AI Engineer
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API Design
March 5, 2024
6 min read

GraphQL Query Optimization

Eliminate GraphQL N+1 query problems using Facebook's DataLoader for efficient batching

GraphQLNode.jsPerformanceDataLoader
The Problem

GraphQL resolvers can trigger N+1 query problems where fetching a list triggers additional queries for each item's relations. This causes severe performance degradation and database overload.

The Solution

Implement DataLoader to batch and cache database requests within a single GraphQL operation. DataLoader automatically groups requests and deduplicates them.

GraphQL Query with DataLoader
graphql
query GetUserPosts($limit: Int!) {
  user {
    id
    posts(limit: $limit) {
      id
      title
      createdAt
    }
  }
}
Key Takeaways
  • Implementing DataLoader for N+1 query prevention
  • Batch and cache database requests automatically
  • Create new DataLoader instances per request
  • Monitor query performance with complexity analysis
Common Use Cases
GraphQL APIs with nested queries
REST APIs with relationship loading
Batch processing with external APIs
Related Resources
DataLoader Documentation