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ML Academy

Production and system design

Interview question

  • midlevel
  • 12 minsuggested time
  • 2ML engineer, Data scientist

Your weekly batch job scores 2 million customers and appends rows to a scores table consumed by the CRM. Last Monday it crashed after writing 1.4 million rows, someone re-ran it, and the CRM then contacted many customers twice. How do you redesign the write path so that retries are safe?

Tests: Idempotent batch design, atomic publication, uniqueness keys, validation before publishing, and failure-mode thinking for data pipelines that feed operational systems.

day 19

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