THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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A random UUID will be generated on topic creation or on migration of an existing topic without topic IDs.
Migration
Upon a controller becoming active, the list of current topics is loaded from /brokers/topics/[topic]. When a topic without a topic ID is found, one will be assigned, and the payload will be rewritten to /brokers/topics/[topic] with id filled with the schema version bumped to version 3. LeaderAndIsrRequest(s) will only be sent by this controller once a topic ID has been successfully assigned to the topic. This process can take place without an inter-broker protocol bump, as the format stored in /brokers/topics/[topic] will be compatible with older broker versions.
Protocol Changes
LeaderAndIsr
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For the time being, we may wish to use the latest protocol versions with clients that do not support topic IDs yet. Until the clients have been updated to refer to partitions by topic ID, we should include both topic name and (optional) ID in every request.
Migration
When a broker receives a LeaderAndIsrRequest containing a topic ID for an existing partition without an associated topic ID, it will associate the topic ID with the partition. This will effectively migrate a broker's local replicas to include topic IDs.
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