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

Motivation

This KIP is try tries to address the following issue issues in Kafka.

1. Log retention might not be honored: Log retention is currently at the log segment level, and is driven off the last modification time of a log segment. This approach does not quite work when a replica reassignment happens because the newly created log segment will effectively have its modification time reset to now.
2. Log rolling might break for a newly created replica as well because of the same reason as (1).

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1. Have only one timestamp concept in Kafka.
2. Enforce the time based log retention / log rolling for different use cases. (Some use case needs to based on LogAppendTime while others prefer CreateTime)
3. Protect the broker from misbehave misbehaving users (e.g. appending wrong create time to messages)

Option 4 adds a configuration to the broker to allow users to decide which timestamp the they want to use according to their use case.

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