Log ingest with PII redaction
Design the ingest-time processing stage of a log platform for a regulated fintech: 500GB/day of logs from 300 services in inconsistent formats (JSON, logfmt, raw text). Requirements: parse/normalize into a common schema, redact PII (card numbers, SSNs, emails) before it's ever persisted, drop noisy debug lines to control cost, and route security-relevant logs to a separate compliance store with 7-year retention while app logs keep 30 days. Design the processing pipeline and the routing.
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.
Clarify4:00 left
Estimate4:00 planned
Design11:30 planned
Deep dive9:30 planned
Failure6:00 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.