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https://issues.apache.org/jira/browse/KAFKA-3806?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15321422#comment-15321422
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James Cheng commented on KAFKA-3806:
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Does the offsets.retention.minutes timer apply to a per topic basis? Per
partition basis? To any topic in for the consumer group?
That is, in the following scenario:
* a consumer listening to a 2 partition topic
* offsets.retention.minutes = 1 day
* partition 1 has no new messages in over a day
* partition 2 has a new message every couple minutes.
Will the offset for partition 1 get deleted, but the offset for partition 2
remain present?
Similarly, in the following scenario:
* a consumer listening to a 2 topics
* offsets.retention.minutes = 1 day
* topic 1 has no new messages in over a day
* topic 2 has a new message every couple minutes.
Will the offset for topic 1 get deleted, but the offset for topic 2 remain
present?
-James
> Adjust default values of log.retention.hours and offsets.retention.minutes
> --------------------------------------------------------------------------
>
> Key: KAFKA-3806
> URL: https://issues.apache.org/jira/browse/KAFKA-3806
> Project: Kafka
> Issue Type: Improvement
> Components: config
> Affects Versions: 0.9.0.1, 0.10.0.0
> Reporter: Michal Turek
> Priority: Minor
>
> Combination of default values of log.retention.hours (168 hours = 7 days) and
> offsets.retention.minutes (1440 minutes = 1 day) may be dangerous in special
> cases. Offset retention should be always greater than log retention.
> We have observed the following scenario and issue:
> - Producing of data to a topic was disabled two days ago by producer update,
> topic wasn't deleted.
> - Consumer consumed all data and properly committed offsets to Kafka.
> - Consumer made no more offset commits for that topic because there was no
> more incoming data and there was nothing to confirm. (We have auto-commit
> disabled, I'm not sure how behaves enabled auto-commit.)
> - After one day: Kafka cleared too old offsets according to
> offsets.retention.minutes.
> - After two days: Long-term running consumer was restarted after update, it
> didn't find any committed offsets for that topic since they were deleted by
> offsets.retention.minutes so it started consuming from the beginning.
> - The messages were still in Kafka due to larger log.retention.hours, about 5
> days of messages were read again.
> Known workaround to solve this issue:
> - Explicitly configure log.retention.hours and offsets.retention.minutes,
> don't use defaults.
> Proposals:
> - Prolong default value of offsets.retention.minutes to be at least twice
> larger than log.retention.hours.
> - Check these values during Kafka startup and log a warning if
> offsets.retention.minutes is smaller than log.retention.hours.
> - Add a note to migration guide about differences between storing of offsets
> in ZooKeeper and Kafka (http://kafka.apache.org/documentation.html#upgrade).
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