51. A query loads 500 posts and performs 501 database queries. What would you investigate first?

Look for an N+1 relationship, such as an author resolver querying the database independently for every post. DataLoader or a carefully designed batch query would be a likely solution.

52. A user can query another user's private profile by changing an ID. What is wrong?

The API is authenticating the user but failing resource-level authorization. Ownership or permission checks must occur on the server before returning the requested resource.

53. A GraphQL mutation succeeds but the UI still displays old data. What could cause this?

The client's cache may not have been updated or invalidated. The application may need a normalized entity update, explicit cache modification, or a refetch depending on the operation.

54. A deeply nested query causes the server CPU to reach 100 percent. What controls could help?

Query depth limits, query complexity analysis, pagination, rate limiting, persisted operations, timeouts, and resolver/data-access optimization can reduce the risk.

55. One field in a dashboard fails while all other fields work. Can GraphQL still return useful data?

Yes, if the schema's nullability permits the failing field to become null. GraphQL can return partial data together with an error describing the failed field.

56. Your GraphQL API has 20 million records and offset pagination becomes slow. What would you consider?

Cursor-based pagination backed by suitable indexed ordering is a strong candidate because large offsets can require the database to skip many records.

57. A GraphQL subscription works locally but fails with multiple server instances. Why?

An in-memory event publisher exists independently in each process. Events need to be distributed through shared infrastructure so all relevant server instances can deliver them to connected clients.

58. A team wants to rename a widely used field immediately. What should you recommend?

Add the replacement field, deprecate the old field, migrate clients, monitor usage, and remove the old field only after compatibility requirements are satisfied.

59. A resolver contains authentication, business rules, five database queries, and an external API call. What architectural problem does this suggest?

The resolver has too many responsibilities. Authentication/context handling and business/data-access logic should be separated into appropriate middleware, services, repositories, or domain modules.

60. When should you avoid introducing GraphQL federation?

Avoid it when a single service is sufficient and the organization does not need independent domain ownership or deployment. Federation introduces distributed-system and governance complexity that should be justified by real requirements.