System designHardsd-g583

Subject Feature storeLevel Senior–Staff~55 minCommon in ML systems interviewsIndustries Technology

Question

Design a feature store serving an organization with hundreds of models, where the same feature definitions must produce training data offline (point-in-time correct over years of history) and low-latency lookups online (sub-10ms p99 at 200k QPS). Some features are batch (daily aggregates), some streaming (last-5-minute counts), and some computed on request. Cover the storage layers, how you guarantee online/offline consistency, and how teams register and discover features.

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

Narrate your design

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Run or narrate your approach, then ask the coach.