Turns on/off automatic balancing of query partitions across nodes. It is used whenever there are changes to the set of live nodes tasked with doing query coordination in the cluster. Existing live queries will be migrated to the new preferred query coordinator node. Queries that do not currently support migration — such as those that have not completed their historical part and those that involve Join Query Functions — will not be migrated but need to be resubmitted. You can trigger a rebalance using the GraphQL mutation optimizeQueryPartitions.