1. A method for executing a query in a database system, in which at least a portion of the query is sent for execution from a first node to a second node, the method comprising: a) sending at least a portion of the query from a first database node to a second database node; b) before completing an execution of the query, determining if processing the at least a portion of the query will cause a half-duplex error in communications between the first database node and the second database node; c) identifying states at the first and second database nodes that potentially cause the half-duplex error; and d) modifying the states identified in step (c) to address the half-duplex error.