Write-ahead log replication
Design a write-ahead-log shipping and replication system that keeps a hot standby (and cross-region replicas) in sync with a primary database for high durability and fast failover. The primary commits thousands of transactions/sec; you must bound data loss on primary failure (a target RPO) and bound failover time (RTO), and support point-in-time recovery. How do you ship the log, apply it on replicas, and fail over safely?
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.
Clarify5:00 left
Estimate5:00 planned
Design15:00 planned
Deep dive12:00 planned
Failure8:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.