SELECT table_name, degree
FROM   user_tables
WHERE   table_name = 'MAIL_LOG';

ALTER SESSION SET PARALLEL_DEGREE_POLICY = AUTO
SELECT /*+ parallel(auto) */  * FROM APPS_GLOBAL.mail_log
SELECT * FROM v$px_session--why it's not returning any records.

show parameter parallel

parallel_max_servers                 integer  1
parallel_min_percent                 integer  0
parallel_min_servers                 integer  0
parallel_min_time_threshold          string   AUTO
parallel_server                      boolean  TRUE
parallel_server_instances            integer  5
parallel_servers_target              integer  1
parallel_threads_per_cpu             integer  2
recovery_parallelism                 integer  0

alter session force parallel dml parallel 8;

select 
    m.SQL_EXEC_ID
   ,m.SQL_EXEC_START
   ,m.PX_QCSID
   ,m.PX_MAXDOP
   ,m.PX_SERVERS_REQUESTED
   ,m.PX_SERVERS_ALLOCATED
from v$sql_monitor m
where 
  m.SQL_ID = :sql_id
-- or: m.sql_exec_id = :sql_exec_id
-- or: m.PX_QCSID = :qc_sid
/

select * 
from v$ses_optimizer_env e
where e.NAME like 'parallel%'
and e.sid=userenv('SID')

ALTER SESSION ENABLE PARALLEL DML
(or)
ALTER SESSION PARALLEL DML PARALLEL 32;

orcl> ALTER SESSION PARALLEL DML PARALLEL 32;
ALTER SESSION PARALLEL DML PARALLEL 32
              *
ERROR at line 1:
ORA-00922: missing or invalid option


orcl> ALTER SESSION ENABLE PARALLEL DML;

Session altered.

orcl>

SQL> alter session FORCE parallel dml parallel 8;

Session altered.

INSERT /*+ append parallel(auto) */ INTO MAIL_LOG@db_apsp t
select * from mail_log;

db121a orcl$ oerr ora 2065
02065, 00000, "illegal option for ALTER SYSTEM"
// *Cause: The option specified for ALTER SYSTEM is not supported
// *Action: refer to the user manual for option supported
db121a orcl$