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When a static member leaves the group, the assignment epochs will be set to 0 in the current assignment record. When the static member rejoins, partitions will therefore be considered to be assigned "from the beginning" (i.e., from epoch 0) to the new member ID. All commits using the old memberId will be fenced, and all commits using the new memberId will be permitted (since all client-side member epochs are larger than 0).

Handling during protocol upgrade

If we upgrade from the classic protocol, we will set the assignment epoch of all partitions to the generation ID of the group. 

If we downgrade to the classic protocol, the assignment epochs will be abandoned, since they are not required in the classic protocol. 

Public Interfaces

ConsumerGroupCurrentMemberAssignmentValue

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