ZooKeeper plays a crucial role in Apache Drill’s distributed architecture by providing coordination and management services. It maintains cluster membership, handles configuration data, and facilitates leader election for the Drillbits. During query execution, ZooKeeper helps distribute work among available nodes, ensuring efficient resource utilization and fault tolerance.
When a client submits a query, the Foreman node consults ZooKeeper to identify active Drillbits and their roles. ZooKeeper assists in selecting an appropriate node based on workload and availability. As queries progress, it monitors Drillbit status, enabling dynamic reassignment of tasks if a node fails or becomes unresponsive.
Additionally, ZooKeeper manages metadata storage, allowing Drillbits to share information about schema changes, table statistics, and partition pruning. This shared knowledge enables better query planning and optimization across the cluster.
