Distributed Idempotency

Concepts: paIdempotency

What They Want to Hear 'Distributed idempotency requires idempotency tokens: a unique identifier for each operation that every downstream system uses to deduplicate. When the pipeline produces output, it tags each write with a deterministic token derived from the input data (e.g., hash of partition date + pipeline version + input checksum). Each downstream system checks: have I already processed this token? If yes, skip. If no, process and record the token. This works across S3, Snowflake, and Kafka because the token is independent of any single system.' This is the answer that shows you can guarantee idempotency without relying on a shared database or distributed transactions. If you describe idempotency as 'just use UPSERT,' the interviewer knows you have only worked with single-writer p