Enables you to increase or decrease the number of active worker processes and/or PQ slaves for the current job.
Syntax and Description
PARALLEL is available as both a command-line parameter and an interactive-mode parameter. You set it to the desired number of parallel processes. An increase takes effect immediately if there are enough resources and if there is enough work requiring parallelization. A decrease does not take effect until an existing process finishes its current task. If the integer 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