System designHardsd-g021

Subject Change data captureLevel Senior–Staff~45 minCommon in Databases & SQL · Distributed systems interviewsIndustries Technology, Software development

Question

Design a cache-invalidation system driven by change-data-capture for a read-heavy product catalog: a multi-region edge cache serves ~2M reads/sec, the source of truth is a primary database, and a price or availability change must invalidate/refresh the relevant cached entries everywhere within a couple seconds. Requirements: no entry stays stale indefinitely, an invalidation storm (bulk price update on 1M SKUs) must not stampede the database, and regions must converge. Walk through capture, propagation, and the failure modes.

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.