Top 4 Pagination Interview Questions

Browse 4 real-world technical and behavioral interview questions about Pagination. Review scenarios, edge cases, and architectural best practices.

Design the home feed for a social network.

Size it first: 200M daily actives opening the feed six times a day is 42k reads/s at peak, while 100M posts fanned out to 200 followers each is 231k feed writes/s, so writes dominate. Push to ordinary accounts, pull for high-follower ones, and store ids so deletes and blocks filter on read.

harddesign

Every message must survive the phone being wiped, and a user has 40,000 of them. Where do they live and how are they paged?

The server holds one row per message, partitioned by conversation and clustered by descending sequence so a page is a contiguous read, and clients page by keyset cursor rather than offset. Per-user state moves to a side table so the body stays shared, and if messages are end-to-end encrypted the wipe is a key-custody question, not a storage one.

harddesign

Design the contract for a public API. How do you handle pagination, idempotency and versioning?

Model resources around client workflows, paginate with an opaque keyset cursor because offset pagination skips and duplicates rows under concurrent writes, make unsafe operations replayable with a client-supplied idempotency key, and evolve additively so that versioning stays a last resort rather than a routine.

harddesign

Clients are asking for page 4,000 of your /orders collection. How is that endpoint paginated, and what would you change?

Offset pagination gets slower with depth and drifts when rows are inserted mid-traversal, so paginate with a keyset comparison on the sort key plus a unique tiebreaker, hand back an opaque cursor and a Link rel=next header, and price an exact total count separately.

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