GraphQL Query Execution
Resolvers, DataLoader Batching & Query Complexity Analysis
Resolver Chain Visualization
A GraphQL query traverses a tree of resolver functions. Each field in the query maps to a resolver that fetches or computes its value. Watch how resolvers fire from root to leaves.
{ user(id: 1) { name posts { title comments { text } } } }
The N+1 Problem
Fetching 5 users and their posts naively creates 6 DB queries (1 for users + 5 for each user's posts). DataLoader batches the 5 individual queries into 1, reducing total queries from 6 to 2.
DataLoader Batching & Caching
DataLoader collects individual .load() calls within a single event loop tick, then fires a single batched request. Subsequent calls for the same key return from cache instantly.
Query Complexity Analysis
Each field in a query has a complexity cost. Scalars cost 1, objects cost 2, and lists multiply their children's cost. Deeply nested lists cause exponential complexity growth.