The node that receives the query figures out which nodes it needs to talk to for an answer, and then it adds the operations to the next batch for those nodes. T

The node that receives the query figures out which nodes it needs to talk to for an answer, and then it adds the operations to the next batch for those nodes. The batch dispatches, the nodes do their work, the batch commits, and the client receives the response. It's not really a full answer, but maybe hints at the architecture.