System designHardsd-g334

Subject TrendingLevel Senior–Staff~45 minCommon in Distributed systems interviewsIndustries Technology

Question

Design a trending-detection system that surfaces topics whose interest is *accelerating*, not just topics that are popular. A perennially-high term (e.g. 'weather') should NOT trend; a term going from 200 to 20,000 mentions in 10 minutes SHOULD. You ingest 800k events/sec across millions of distinct terms, want updates every ~30s, and must resist a coordinated bot push of a hashtag. Define the trending score, the windowing, and the abuse defenses.

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.

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