并行进程问题

SQL> select * from v$mystat where rownum<2;

       SIDSTATISTIC#    VALUE

---------- ---------- ----------

       858     0        0

SQL> select /*+ parallel(t 4)*/ count(*),agmt_id fromF_AGT_COMR_INTDIST_H t group by agmt_id;

出现9个进程

SQL> select * from v$mystat whererownum<2;

      SID STATISTIC#        VALUE

---------- ---------- ----------

      860        0            0

SQL> select /*+ parallel(t 4)*/count(*),agmt_id from F_AGT_COMR_INTDIST_H t group by agmt_id order by agmt_id;

出现9个进程