System designHardsd-p120

Subject ConsistencyLevel Senior~45 minCommon in Databases & SQL interviewsIndustries Technology, Software development

Question

Design a reliable event-publishing mechanism so that whenever a service commits a database change, a corresponding event is published to a message bus exactly once — solving the dual-write problem.

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.