Multi-region payment ledger
Design a multi-region payment ledger for a global checkout platform processing 8k authorizations/sec across three regions (US, EU, APAC). Money movement must be exactly-once and auditable; EU cardholder data must stay in-region (PSD2/GDPR). Reads (balance/history) are 20x writes and tolerate a few seconds of staleness, but a captured charge must never be double-captured even during a regional failover. How do you partition the ledger, place writes, and keep the books correct across regions?
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.
Clarify5:30 left
Estimate5:30 planned
Design16:30 planned
Deep dive13:30 planned
Failure9:00 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.