System designHardsd-g104

Subject Feature storeLevel Senior–Staff~45 minCommon in ML systems · Distributed systems interviewsIndustries Technology

Question

Design the streaming feature pipeline that computes real-time aggregate features for a ride-hailing surge/fraud model: features like 'ride requests in this geohash in the last 5 minutes', 'driver cancellations in the last hour', updated continuously and read at inference with single-digit-ms latency. Events arrive out of order and occasionally late by minutes. Design the streaming aggregation + serving so the online feature values are correct under out-of-order/late events and don't drift from the offline-recomputed truth.

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.