A live TV vote at a million writes a second: spread by key, buffer in Kafka, aggregate the hot counter in two stages, shed what can wait.
Infrastructure, platform and reliability engineers.
Your approach: Use diagrams or prose to explain responsibilities, state, capacity and failure behavior. Show the calculations requested by the question.
Design for Write Scale: A Million Writes a Second. A live TV vote at a million writes a second: spread by key, buffer in Kafka, aggregate the hot counter in two stages, shed what can wait. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.
Resolve the scoping questions for for Write Scale: A Million Writes a Second. Separate stated behavior from assumptions, and identify what is outside your design.
Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.
Explain how your guarantees hold in a difficult case relevant to this subject. Address: Regions? Fraud?
Identify users, required behavior and exclusions. Answer: How many writes? What does "received" promise?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: How fresh is the tally? Can anything be dropped?
Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.
Draw or describe the responsibilities needed for for Write Scale: A Million Writes a Second. Trace a representative request, event or job from its input to a visible result; identify durable state owners.
Walk through a difficult case step by step, including detection and recovery. Consider: Is the peak predictable? Regions? Fraud?
Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.