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Kyuubi High Availability Guide
As an enterprise-class ad-hoc SQL query service built on top of Apache Spark, Kyuubi takes high availability(HA) as a major characteristic, aiming to ensure an agreed level of service availability, such as a higher than normal period of uptime.
Running Kyuubi in HA mode is to use groups of computers or containers that support SQL query service on Kyuubi that can be reliably utilized with a minimum amount of down-time. Kyuubi operates by using Apache ZooKeeper to harness redundant service instances in groups that provide continuous service when one or more components fail.
Without HA, if a server crashes, Kyuubi will be unavailable until the crashed server is fixed. With HA, this situation will be remedied by hardware/software faults auto-detecting, and immediately another Kyuubi service instance will be ready to serve without requiring human intervention.
Load Balance Mode
Load balancing aims to optimize all Kyuubi service unit's usage, maximize throughput, minimize response time, and avoid overload of a single unit. Using multiple Kyuubi service units with load balancing instead of a single unit may increase reliability and availability through redundancy.
With Hive JDBC Driver, a client can specify service discovery mode in JDBC connection string, i.e. serviceDiscoveryMode=zooKeeper; and set zooKeeperNamespace=kyuubi;, then it can randomly pick one of the Kyuubi service uris from the specified ZooKeeper address in the /kyuubi path.
When we specify the ZooKeeper address via kyuubi.ha.zookeeper.quorum, load balance mode is activated by default. Please make sure that you specify the correct ZooKeeper address via kyuubi.ha.zookeeper.quorum and kyuubi.ha.zookeeper.client.port. For more details, see Introduction to the Kyuubi Configurations System