oracle11gR2 sys用户执行dbms_resource_manager.switch_consumer_group_for_user(' user','newgroup ');执行成功,但是select username,resource_consumer_group from v$session;显示user的group还是初始group,并没有切换到newgroup,是怎么回事?向高手求教,还有dbms_resource_manager.switch_consumer_group_for_sess('sid','serial#','newgroup');也不行,PL/SQL却都执行性成功了,为什么呢