18 Performance (N+1 & DataLoader) questions from the GraphQL bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch
B.a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
C.an optimization sending a hash instead of the full document, with the server caching the text after a first registration
D.the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
Answer + AI explanation with Pro
2. Which term means: "the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch"?
Junior
A.Batching
B.DataLoader
C.N+1 problem
D.Automatic persisted queries
Answer + AI explanation with Pro
3. Which statement is correct?
Junior
A.N+1 problem — collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
B.N+1 problem — an optimization sending a hash instead of the full document, with the server caching the text after a first registration
C.N+1 problem — the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch
D.N+1 problem — the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
Answer + AI explanation with Pro
4. What is DataLoader?
Mid
A.collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
B.a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
C.the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
D.an optimization sending a hash instead of the full document, with the server caching the text after a first registration
Answer + AI explanation with Pro
5. Which term means: "a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches"?
Mid
A.Batching
B.Per-request cache
C.DataLoader
D.N+1 problem
Answer + AI explanation with Pro
6. Which statement is correct?
Mid
A.DataLoader — scoring a document's cost before execution to reject overly expensive or deeply nested requests
B.DataLoader — an optimization sending a hash instead of the full document, with the server caching the text after a first registration
C.DataLoader — the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
D.DataLoader — a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
Answer + AI explanation with Pro
7. What is Batching?
Mid
A.collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
B.scoring a document's cost before execution to reject overly expensive or deeply nested requests
C.the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch
D.an optimization sending a hash instead of the full document, with the server caching the text after a first registration
Answer + AI explanation with Pro
8. Which term means: "collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request"?
Mid
A.Automatic persisted queries
B.Batching
C.DataLoader
D.N+1 problem
Answer + AI explanation with Pro
9. Which statement is correct?
Mid
A.Batching — the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
B.Batching — collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
C.Batching — a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
D.Batching — the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch
Answer + AI explanation with Pro
10. What is Per-request cache?
Mid
A.a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
B.the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
C.scoring a document's cost before execution to reject overly expensive or deeply nested requests
D.collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
Answer + AI explanation with Pro
11. Which term means: "the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id"?
Mid
A.Query complexity analysis
B.Batching
C.N+1 problem
D.Per-request cache
Answer + AI explanation with Pro
12. Which statement is correct?
Mid
A.Per-request cache — a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
B.Per-request cache — an optimization sending a hash instead of the full document, with the server caching the text after a first registration
C.Per-request cache — the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
D.Per-request cache — collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
Answer + AI explanation with Pro
13. What is Query complexity analysis?
Senior
A.an optimization sending a hash instead of the full document, with the server caching the text after a first registration
B.collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
C.the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
D.scoring a document's cost before execution to reject overly expensive or deeply nested requests
Answer + AI explanation with Pro
14. Which term means: "scoring a document's cost before execution to reject overly expensive or deeply nested requests"?
Senior
A.DataLoader
B.N+1 problem
C.Per-request cache
D.Query complexity analysis
Answer + AI explanation with Pro
15. Which statement is correct?
Senior
A.Query complexity analysis — a per-request utility that batches and caches backend key lookups within a single tick to eliminate redundant fetches
B.Query complexity analysis — scoring a document's cost before execution to reject overly expensive or deeply nested requests
C.Query complexity analysis — the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
D.Query complexity analysis — collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
Answer + AI explanation with Pro
16. What is Automatic persisted queries?
Senior
A.collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
B.an optimization sending a hash instead of the full document, with the server caching the text after a first registration
C.scoring a document's cost before execution to reject overly expensive or deeply nested requests
D.the short-lived memoization of loaded keys, scoped to one operation, that dedupes repeat lookups for the same id
Answer + AI explanation with Pro
17. Which term means: "an optimization sending a hash instead of the full document, with the server caching the text after a first registration"?
Senior
A.DataLoader
B.Per-request cache
C.Automatic persisted queries
D.N+1 problem
Answer + AI explanation with Pro
18. Which statement is correct?
Senior
A.Automatic persisted queries — scoring a document's cost before execution to reject overly expensive or deeply nested requests
B.Automatic persisted queries — collapsing many individual same-type key lookups gathered in one event-loop tick into a single backend request
C.Automatic persisted queries — an optimization sending a hash instead of the full document, with the server caching the text after a first registration
D.Automatic persisted queries — the inefficiency where resolving a list triggers one backend call per item plus the initial list fetch
Answer + AI explanation with Pro
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