Status

Current state:  Under DiscussionAccepted

Discussion thread: here

JIRA: 

PR: https://github.com/apache/kafka/pull/4648

Released: TBD2.0

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

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The only impact is that the default configuration will a) hold onto offsets for longer and b) hold onto offsets for more consumer groups for longer. (a) shouldn't be an issue since the offsets topic is compacted. According to Jun, (b) was one of the reasons for selecting the 24h retention and is potentially more of a concern since it increases the storage required for the offsets topic and the amount of memory required for the offset cache in the broker. However, the improved user experience outweighs this cost. The cost should only be large if users automatically create large numbers of ephemeral consumer groups. The most common case for this is probably use of the console consumer, which has offset commit enabled by default (despite most use being for ephemeral groups for debugging/inspection).

Compatibility, Deprecation, and Migration Plan

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No migration tool is required, but we'll want to include a mention in the upgrade notes.

Test Plan

None. This is a simple change to an already tested configuration. Adjustments to existing unit tests will sufficiently cover testing this.

Rejected Alternatives

None