System designHardsd-g009

Subject Fan outLevel Senior–Staff~45 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design the home-feed delivery for a creator platform where most users follow 100–500 creators, but a small number of mega-creators have 50M+ followers and post several times a day. Feeds must load in under 300ms and show new posts within seconds for normal accounts. Decide between fan-out-on-write and fan-out-on-read, justify the hybrid, and explain how you handle the mega-creator post storm without melting the write path.

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.