System designMediumsd-g432

Subject Data qualityLevel Mid–Senior~35 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

A financial reporting warehouse aggregates transactions from a streaming pipeline (real-time) and a separate batch settlement file from the payment processor (authoritative, arrives next day). The two frequently disagree: the streaming total and the settlement total differ by small amounts due to dropped/late events, retries, currency rounding, and timezone cutoffs. Design an automated reconciliation system that detects, classifies, and surfaces these discrepancies so finance can trust the numbers and auditors can see a clean trail.

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

Loading whiteboard…

Run or narrate your approach, then ask the coach.