Code Room
System designHard
Question
Design an LSM-tree (log-structured merge) storage engine to back a write-heavy key-value store: ~500K writes/sec of 200-byte records, a 10:1 write-to-read ratio, point lookups and short range scans, and a strict durability guarantee that an acknowledged write survives a single-node crash. Walk through the in-memory and on-disk structures, how reads are served, and how background work keeps the engine healthy under sustained load.
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.