Time-series database
Design a time-series database for infrastructure metrics ingesting 4 million data points/sec from 500k hosts, each emitting ~200 series. Queries are mostly recent-window dashboards (last 1–6 hours) with occasional 90-day rollups. Storage must stay affordable while keeping recent data fast. How do you model series, lay out storage, and handle retention and high-cardinality tags?
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.