Contention caused by communication between parallel query processes.
Solutions
Decrease the degree of parallelism for the queries Tune the parallel_execution_message_size parameter (may require larger amounts of memory) Disable parallel query if these waits taken longer than a serial run (parallel_max_servers=0)
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1277877
