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This KIP is only implemented for the internal topic __cluster_metadata. An increase of the inter broker protocol (IBP) is not required, since we are only implementing this for the __cluster_metadata topic partition, that partition is a new partition and will be handle by the KafkaRaftClient. Internal and external clients for all other topics can ignore the SnapshotId as that field will not be set for topic partitions that are not __cluster_metadata.

The IBP will be increase when adding support for KIP-595 and KIP-630 to existing topic partition that are not __cluster_metadata.

Rejected Alternatives

Append the snapshot to the Kafka log: Instead of having a separate file for snapshots and separate RPC for downloading the snapshot, the leader could append the snapshot to the log. This design has a few drawbacks. Because the snapshot gets appended to the head of the log that means that it will be replicated to every replica in the partition. This will cause Kafka to use more network bandwidth than necessary.

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