ORACLE 11gR2 - Parallel Operation

PARALLEL_DEGREE_POLICY [manual]:
AUTO - Enables automatic degree of parallelism, statement queuing, and in-memory parallel execution.

PARALLE_DEGREE_LIMIT [cpu]:
The maximum degree of parallelism is limited by the number of CPUs in the system. The formula used to calculate the limit is PARALLEL_THREADS_PER_CPU * CPU_COUNT * the number of instances available.

PARALLEL_FORCE_LOCAL [FALSE]:
This parameter specifies whether a SQL statement executed in parallel is restricted to a single instance in an Oracle RAC environment. By setting this parameter to TRUE, you restrict the scope of the parallel server processed to the single Oracle RAC instance where the query coordinator is running.

PARALLEL_MIN_TIME_THRESHOLD [AUTO=10sec]:
Minimum execution time a statement should have before the statement is considered for automatic degree of parallelism.

SQL> show parameter parallel
NAME                                          TYPE        VALUE
------------------------------------ ----------- -----------
fast_start_parallel_rollback              string         LOW
parallel_adaptive_multi_user            boolean     TRUE
parallel_automatic_tuning                 boolean     FALSE
parallel_degree_limit                    string         CPU
parallel_degree_policy                 string          MANUAL
parallel_execution_message_size      integer       16384
parallel_force_local                      boolean     TRUE [FALSE]
parallel_instance_group                    string
parallel_io_cap_enabled                   boolean     FALSE
parallel_max_servers                         integer      0
parallel_min_percent                         integer      0
parallel_min_servers                          integer      0
parallel_min_time_threshold         string         AUTO [ Default 10 sec]
parallel_server                                   boolean    FALSE
parallel_server_instances                   integer      1
parallel_servers_target                       integer      64
parallel_threads_per_cpu                   integer      2
recovery_parallelism                          integer       0