Rewinding a commit offset

[arthurprs]

Is there anything I should be aware off while trying to "rewind" a consumer group committed offset? E.g. commit(2) then commit(1). I can't for the life of me get this to work with librdkafka. The "rewind" commit seems to get ignored.

The relevant log lines after calling rd_kafka_offset_store

2022-05-23T16:00:14.037941Z DEBUG librdkafka: librdkafka: CGRPOP [thrd:main]: Group "1e807980-981f-4a83-bf9e-5891326a1e7d" received op OFFSET_COMMIT in state up (join-state init)
2022-05-23T16:00:14.037997Z DEBUG librdkafka: librdkafka: OFFSET [thrd:main]: Topic hydra-txns-330254185349358220317734126890437208460 [0]: stored offset 1, committed offset 2: not including in commit
2022-05-23T16:00:14.038041Z DEBUG librdkafka: librdkafka: COMMIT [thrd:main]: OffsetCommit for 1 partition(s) in join-state init: manual: returned: Local: No offset stored

The error in the client is RD_KAFKA_RESP_ERR__NO_OFFSET which is not to be considered an error according to the docs.

[edenhill]

librdkafka will not allow you to commit an older offset than what is already committed, unless you explicitly call commit() with offsets specified.

[arthurprs]

Thank you! Switching to rd_kafka_commit did the trick 🎉