System designHardsd-g665

Subject Time series databaseLevel Senior–Staff~45 minCommon in Databases & SQL interviewsIndustries Technology, Software development

Question

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.