Exactly-once Semantics is Possible: Here's How Apache Kafka Does itThis post was originally published in 2017 and last updated March 2025. I’m thrilled that we have hit an exciting milestone the Apache Kafka® community has long been waiting for: we have introduced exactly-once semantics in Kafka in the 0.11 release and Confluent Platform 3.3. In this post, I’d like to tell you what Kafka’s exactly-once semantics mean, why it is a hard problem, and how the new id
