Stream Guarantees

Concepts: paStreamProcessing

What They Want to Hear 'Exactly-once means every event is processed exactly one time, with no loss and no duplicates. In practice, most production systems use at-least-once delivery with idempotent writes downstream, because true exactly-once is expensive.' This is the answer that shows real-world experience. Candidates who say 'just use exactly-once' without mentioning the cost are waving a red flag.