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1. Controller path: stores the current controller info.

   Code Block
   /controller --> {brokerid} (ephemeral; created by controller)

2. Broker path: stores the information of all live brokers.

   Code Block
   /brokers/ids/[broker_id] --> host:port (ephemeral; created by admin)

3. Topic path: stores the replication assignment for all partitions in a topic. For each replica, we store the id of the broker to which the replica is assigned. The first replica is the preferred replica. Note that for a given partition, there is at most 1 replica on a broker. Therefore, the broker id can be used as the replica id

   Code Block
   /brokers/topics/[topic] --> {part1: [broker1, broker2], part2: [broker2, broker3] ...} (created by admin)

4. LeaderAndISR path: stores leader and ISR of a partition

   Code Block
   /brokers/topics/[topic]/[partition_id]/leaderAndISR --> {leader_epoc: epoc, leader: broker_id, ISR: {broker1, broker2}}   This path is updated by the controller or the current leader. The current leader only updates the ISR part. Updating the path requires synchronization using conditional updates to Zookeeper.

5. PartitionReassignment path: This path is used when we want to reassign some partitions to a different set of brokers. For each partition to be reassigned, it stores a list of new replicas and their corresponding assigned brokers. This path is created by an administrative process and is automatically removed once the partition has been moved successfully

   Code Block
   /admin/partitions_reassigned/[topic]/[partition_id] --> {broker_id …} (created by admin)

6. PartitionAdd and PartitionRemove path: The paths are used when we want to add/remove partitions to an existing topic. For each partition to be added, the PartitionAdd path stores a list of new replicas and their corresponding assigned brokers. The paths are created by an administrative process and are automatically removed by the controller once the change is complete.

   Code Block
   /admin/partitions_add/[topic]/[partition_id] \--> {broker_id …} (created by admin) /admin/partitions_remove/[topic]/[partition_id] (created by admin)

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