Transactions and Exactly-Once

An idempotent producer stops duplicates within one session (Idempotent Producers). Transactions go further: a group of writes to several partitions, together with the consumer offsets that produced them, becomes visible all at once or not at all, even across crashes. This is what Kafka 129 means by exactly-once semantics (EOS), and it covers reading from and writing to Kafka only.

Subsections

• The Transaction Coordinator
• The Transactional Producer API
• Isolation Levels
• Exactly-Once Patterns
• Exactly-Once in Practice