If you set this parameter too low, then some queries may not have a parallel execution process available to them during query processing. If you set it too high, then memory resource shortages may occur during peak periods, which can degrade performance.
如果设置这个参数过小，那么某些查询在查询过程中可能没有并行执行进程活动。如果设置这个参数过大，那么在峰值期间内存资源可能不足，导致性能下降。
PARALLEL_MIN_SERVERS specifies the minimum number of parallel execution processes for the instance. This value is the number of parallel execution processes Oracle creates when the instance is started.
PARALLEL_MIN_SERVERS指定实例并行执行进程数的最小值。这个值是实例在启动时，Oracle创建的并行执行进程数。
PARALLEL_THREADS_PER_CPU specifies the default degree of parallelism for the instance and determines the parallel adaptive and load balancing algorithms. The parameter describes the number of parallel execution processes or threads that a CPU can handle during parallel execution.
PARALLEL_THREADS_PER_CPU指定实例默认的并行度，确定合适的并行和负载均衡算法。这个参数描述并行执行进程数，或者在并行执行期间CPU能处理的线程数。
The default is platform-dependent and is adequate in most cases. You should decrease the value of this parameter if the machine appears to be overloaded when a representative parallel query is executed. You should increase the value if the system is I/O bound.
默认值依赖于平台，在大多数情况下都是合适的。当执行一个典型的并行查询时，服务器出现过载的情况，应该减少这个参数的值。如果系统在I/O的边界应该增加这个值。
在并行参数方面，有以下最佳实践：