System designMediumsd-g556

Subject Data processingLevel Entry–Mid~30 minCommon in Concurrency interviewsIndustries Software development, Technology

Question

Design a CSV report generator for a SaaS dashboard. A user clicks 'export', and the system produces a CSV of their data (could be a few rows or up to a few hundred thousand) and lets them download it. Small reports should feel instant; large ones can take a while. Describe how you generate the file and deliver it to the user without timing out the web request.

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.