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
