Oracle Database computes defaults for the parallel execution parameters based on the value at database startup of
PARALLEL_THREADS_PER_CPU. The parameters can also be manually tuned, increasing or decreasing their values to suit specific system configurations or performance goals. For example, on systems where parallel execution is never used,
PARALLEL_MAX_SERVERS can be set to zero.
You can also manually tune parallel execution parameters. Parallel execution is enabled by default.
Initializing and tuning parallel execution involves the following steps: