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The Real Price of GraphQL

A team wants to adopt GraphQL to “fix over-fetching and the N+1 calls from mobile”. What does GraphQL actually buy, and what does it cost?

Practical scenario

After migrating, p99 latency doubles: the products resolver fires one SQL query per item in a 100-item list, something the old handcrafted REST endpoint did in one join.

What it tests

  • • Whether the candidate knows where N+1 goes rather than believing it disappears
  • • Server-side costs: resolvers, authorization, caching, query cost control
  • • Fit assessment: consumer diversity as the real justification