新特性：CDB/PDB的维护命令：CDB、PDB的用户管理（4）CDB的用户（c##开头的），在CDB能查看PDB的数据

CDB的用户（c##开头的），除了sys用户，默认情况在CDB不能查看PDB的数据，例如v_$session的数据，需要通过alter user c##viewpdb set container_data进行赋权。

1、创建一个CDB的用户并赋权

SQL>  conn / as sysdba
Connected.
SQL> select con_id,count(*) from sys.v_$session group by con_id;

    CON_ID   COUNT(*)
---------- ----------
         1          5
         5          1
         3          1
         0         89

SQL> create user c##viewpdb1 identified by test ;

User created.

SQL> grant create session, set container to c##viewpdb1 container=all;

Grant succeeded.

SQL> grant select on v_$session to c##viewpdb1 container=all;

Grant succeeded.

2、验证

默认情况下c##viewpdb1只能查看con_id in (0,1)

SQL> conn c##viewpdb1/test
Connected.
SQL> select con_id,count(*) from sys.v_$session group by con_id;

    CON_ID   COUNT(*)
---------- ----------
         1          5
         0         89

3、赋权

SQL> conn / as sysdba
Connected.
SQL> alter user c##viewpdb1 set container_data =(CDB$ROOT,PDB1_WHS,PDB3_WHS）for v_$session container=current;

User altered.

4、验证能否查看

SQL> conn c##viewpdb1/test
Connected.
SQL> select con_id,count(*) from sys.v_$session group by con_id;

    CON_ID   COUNT(*)
---------- ----------
         1          5
         5          1
         3          1
         0         89