This example restricts all queries started in the current session to 5 worker processes:
set parallel_degree 5
While this command is in effect, any query on a table with more than 5 partitions cannot use a partition-based scan.
To remove the session limit, use:
set parallel_degree 0 or set scan_parallel_degree 0
To run subsequent queries in serial mode, use:
set parallel_degree 1 or set scan_parallel_degree 1