Exactly-Once Semantics in Kafka: Understanding the Reality
Kafka's exactly-once semantics ensures delivery within the cluster, but external operations can cause issues.
Kafka's exactly-once semantics (EOS) ensures message delivery within the Kafka cluster but not beyond it. While producer idempotence and transactions help prevent duplicates, operations outside Kafka, like database writes, can still lead to issues. Engineers must design idempotent consumers and consider patterns like the transactional outbox to achieve end-to-end safety.