I am working with an application that is running rules based optimization against a RAC database. The app vendor has recommended MAX_PARALLEL_SERVERS be set to 0. But this breaks certain things, such as GV$ views. The app vendor states that if MAX_PARALLEL_SERVERS is set to 1 or greater, then queries with index hints switches from rules based to cost based and, according to the vendor, performance is degraded.
Is there a way to stop this switch when index hints are used with rules based optimization and MAX_PARALLEL_SERVERS set to 1 or greater.