Enables you to increase or decrease the number of active processes (worker and parallel slaves) for the current job.
Syntax and Description
PARALLEL is available as both a command-line parameter and as an interactive-command mode parameter. You set it to the desired number of parallel processes (worker and parallel slaves). An increase takes effect immediately if there are sufficient files and resources. A decrease does not take effect until an existing process finishes its current task. If the value is decreased, then workers are idled but not deleted until the job exits.
This parameter is valid only in the Enterprise Edition of Oracle Database 11g or later.
"PARALLEL" for more information about parallelism