I'm not the one who wrote the original comment, so I can't modify it. But one should still commit offsets because it is the happy-path; DB transaction successful? Commit offset. If the latter fails due to e.g application crash and you seek at startup to the partition offset stored in the DB + 1, you get exactly-once semantics. There's some more details, e.g you'd have to do the same during consumer group rebalance, and topic configuration also plays a role, for example if the topic is a compacted topic or not, and if you write tombstones, what its retention policy is.