Designing for Reprocessability

The closing question in any late-data interview: 'Can you reprocess this pipeline from scratch?' This tests whether your entire design is built for reprocessability or whether it has hidden assumptions that break on rerun. Candidates who say 'yes, because every component is idempotent and parameterized by date' pass. Candidates who hesitate fail. The Three Things the Interviewer Wants to Hear The Pattern You Should Be Able to Write Idempotent DELETE-INSERT per Partition The DELETE-INSERT pattern inside a transaction is idempotent: run it once or five times, same result. The loaded_at timestamp records the reprocessing time. The aggregate metadata table triggers downstream recomputation. The Operational Checklist That Closes the Answer Vocabulary That Signals Seniority