Oracle Database 12c does not acknowledge parallel_min_server value to be lower than default

When I changed the value of parallel_min_server from 512 to 256, the change did not take place Although parallel_min_servers was set to 256, Oracle continue to start 512 processes at startup.


SQL> show parameters parallel_min_servers ;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
parallel_min_servers                 integer     512



SQL> alter system set parallel_min_servers=256 ;

System altered.

SQL> show parameters parallel_min_servers;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
parallel_min_servers                 integer     256
SQL> shutdown
SQL> startup



However, the number of ora_p0* process continued to be 512

Even the system view showed the process count to be 512

SQL> set line 80
SQL> set tab off
SQL> col statistic for a30
SQL>
SQL> select * from v$px_process_sysstat where statistic like '%Server%';

STATISTIC                           VALUE     CON_ID
------------------------------ ---------- ----------
Servers In Use                          0          0
Servers Available                     512          0
Servers Started                       512          0
Servers Shutdown                        0          0
Servers Highwater                       0          0
Servers Cleaned Up                      0          0
Server Sessions                         0          0

7 rows selected.

SQL>

According to metalink note 1678111.1, this is a known/expected behaviour. In Oracle DB 12c ,there is no lower level permissible any longer that is lower than the default