Code Room
System designMedium
Question
Design a versioned document store (S3-versioning / Google-Docs-revision style) that keeps every version of an object and supports reading any prior version, restoring an old version, and soft-deletes. Constraints: most reads target the latest version, version history can be long, you bill on stored bytes so old versions must be reclaimable by policy, and listing must show only current versions by default. Cover the version model, read path, and lifecycle.
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.
Learn the concepts
Loading whiteboard…
Run or narrate your approach, then ask the coach.