Debezium Blog

Every now and then there is a questions in the Debezium chat or on the mailing list how to ensure exactly-once delivery of the records produced by Debezium. So far Debezium aimed only for at-least-once delivery. This means Debezium guarantees every single change will be delivered and there is no missing or skipped change event. However, in case of failures, restarts or DB connection drops, the same event can be delivered more than once. Typical scenario is that the event is delivered twice - once before failure/restart and second time after that. Exactly-once delivery (or semantic) provides stronger guarantee - every single message will be delivered and at the same time there won’t be any duplicates, every single message will be delivered exactly once. So far our answer was that the users have to implement their own deduplication system if they need exactly-once delivery. However, with Kafka Connect support for exactly-once delivery, it seems we can provide exactly-once delivery for Debezium connectors out-of-the-box, only with a little configuration change.