This is a space from which to link to pages related to Kafka's exactly once semantics.
KIPs / Design docs
KIP-98 - Exactly Once Delivery and Transactional Messaging
Exactly once detailed design doc
Exactly once perf numbers
KIP-185: Make exactly once in order delivery per partition the default producer setting
KIP-129: Streams Exactly-Once Semantics
Implementation notes
Kafka Exactly Once - Solving the problem of spurious OutOfOrderSequence errors
Kafka Exactly Once - Dealing with older message formats when idempotence is enabled