[jira] [Commented] (KAFKA-20275) API to set commit offsets without being subscribed

["Lianet Magrans (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-20275?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18064164#comment-18064164 ] 

Lianet Magrans commented on KAFKA-20275:
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Hey [~wdaehn], the consumer.commit API does not require to subscribe first really, it can be used with manual assignment (consumer.assign) as long as the consumer has configured a group.id

There are integration tests showing flows similar to what I understand you want to achieve (assign + commit + other consumers seeing the new committed offset and consuming from it), e.g. 

[https://github.com/apache/kafka/blob/4ea29da3ca1776f6870905eed015ef5751e4866c/clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/PlaintextConsumerAssignTest.java#L247]

Is that the sequence that you're looking for? Let me know, hope it helps! 

> API to set commit offsets without being subscribed
> --------------------------------------------------
>
>                 Key: KAFKA-20275
>                 URL: https://issues.apache.org/jira/browse/KAFKA-20275
>             Project: Kafka
>          Issue Type: Improvement
>          Components: consumer
>    Affects Versions: 4.1.1
>            Reporter: Werner Daehn
>            Priority: Minor
>
> Imagine you want to reset the consumer offset to something earlier. The last delta load from offset 100-200 was technically successful but you need to run it again.
> So you want to change the offset for topic1/partition0 to 100 again.
> But you cannot, because the only API allowing to change offsets is the consumer api and that requires to subscribe first. Without the subscribe, assign only, you get a `Commit failed: Broker: Unknown member`.
> But subscribe assigns partitions to you instead of you being in control of what partitions you want to change.
>  
> Hence the procedure should be:
>  * consumer.assign(topicpartitions)
>  * consumer.commit(topicpartitions)
>  * a rebalance is triggered for all existing consumers to notify them about the commit offset change.



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