System designHardsd-g252

Subject Image processingLevel Senior–Staff~45 minCommon in ML systems interviewsIndustries Technology

Question

Design the batch image-processing pipeline for a photo-cloud product that, on upload, must run a chain of ML and CV steps per photo — EXIF extraction, face detection + clustering, object/scene labels, OCR, and NSFW screening — for 2B photos/day, and must also support re-running the whole chain over the entire 500B-photo back-catalog when a model is upgraded. Design the per-photo pipeline, how you schedule the steps, and how you do a full backfill without melting the live ingest path.

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.