Exactly-Once Processing Semantics

In distributed systems, ensuring messages are processed exactly once is a significant challenge. This is the 'holy grail' for data integrity, meaning each message triggers its intended effect precisely one time, no more, no less.

Achieving this prevents critical issues like duplicate payments or incorrect inventory counts.

By default, Kafka often provides at-least-once delivery semantics. This means a message is guaranteed to be delivered, but it might be delivered multiple times due to network issues, consumer crashes, or retries.

These duplicates are the primary hurdle to achieving exactly-once processing in your application logic.