Exactly-Once Semantics Are Possible: Here’s How Kafka Does It

The Apache Kafka community has introduced exactly-once semantics in Kafka, which enables correct exactly-once stream processing using the Kafka Streams API. This feature provides end-to-end guarantees for deterministic operations and non-deterministic operations with a subset of legal outputs. The feature was designed to provide minimal performance overhead and to make Kafka faster for everyone. It involves idempotence and transactions features that work together to ensure correct exactly-once stream processing. The feature is available in Apache Kafka 3.8.0 and Confluent Platform v3.3 and later, including Confluent Cloud.