Multitenant : Connecting to Container Databases (CDB) and Pluggable Databases (PDB) in Oracle Database 12c Release 1 (12.1)

Connecting to a Container Database (CDB)

Connecting to the root of a container database is the same as that of any previous database instance. On the database server you can use OS Authentication.

$ export ORACLE_SID=cdb1
$ sqlplus / as sysdba

SQL*Plus: Release 12.1.0.1.0 Production on Mon Aug 26 15:29:49 2013

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL>

The V$SERVICES views can be used to display available services from the database.

COLUMN name FORMAT A30

SELECT name, pdb
FROM   v$services
ORDER BY name;

NAME          PDB
------------------------------ ------------------------------
SYS$BACKGROUND                 CDB$ROOT
SYS$USERS                      CDB$ROOT
cdb1                           CDB$ROOT
cdb1XDB                        CDB$ROOT
pdb1                           PDB1
pdb2                           PDB2

6 rows selected.

SQL>

Displaying the Current Container

The SHOW CON_NAME and SHOW CON_ID commands in SQL*Plus display the current container name and ID respectively.

SQL> SHOW CON_NAME

CON_NAME
------------------------------
CDB$ROOT
SQL>

SQL> SHOW CON_ID

CON_ID
------------------------------
1
SQL>

They can also be retrieved using the SYS_CONTEXT function.

SELECT SYS_CONTEXT('USERENV', 'CON_NAME')
FROM   dual;

SYS_CONTEXT('USERENV','CON_NAME')
--------------------------------------------------------------------------------
CDB$ROOT

SQL>


SELECT SYS_CONTEXT('USERENV', 'CON_ID')
FROM   dual;

SYS_CONTEXT('USERENV','CON_ID')
--------------------------------------------------------------------------------
1

SQL>

Switching Between Containers

When logged in to the CDB as an appropriately privileged user, the ALTER SESSION command can be used to switch between containers within the container database.

SQL> ALTER SESSION SET CONTAINER=pdb1;

Session altered.

SQL> SHOW CON_NAME

CON_NAME
------------------------------
PDB1
SQL> ALTER SESSION SET CONTAINER=cdb$root;

Session altered.

SQL> SHOW CON_NAME

CON_NAME
------------------------------
CDB$ROOT
SQL>

From Oracle 12.2 onward the ALTER SESSION command can also specify the service within the container. We can demonstrate this by creating a new service in a PDB, then switching to that service.

CONN / AS SYSDBA
ALTER SESSION SET CONTAINER=pdb1'

BEGIN
  DBMS_SERVICE.create_service('my_new_service','my_new_service');
  DBMS_SERVICE.start_service('my_new_service');
END;
/

ALTER SESSION SET CONTAINER=pdb1 SERVICE=my_new_service;

COLUMN con_id FORMAT A10
COLUMN service_name FORMAT A30

SELECT SYS_CONTEXT('USERENV', 'CON_ID') AS con_id,
       SYS_CONTEXT('USERENV', 'SERVICE_NAME') AS service_name
FROM   dual;

CON_ID     SERVICE_NAME
---------- ------------------------------
6          my_new_service

SQL>

Connecting to a Pluggable Database (PDB)

Direct connections to pluggable databases must be made using a service. Each pluggable database automatically registers a service with the listener. This is how any application will connect to a pluggable database, as well as administrative connections.

SQL> -- EZCONNECT
SQL> CONN system/password@//localhost:1521/pdb1
Connected.
SQL>

SQL> -- tnsnames.ora
SQL> CONN system/password@pdb1
Connected.
SQL>

The connection using a TNS alias requires an entry in the "$ORACLE_HOME/network/admin/tnsnames.ora" file, such as the one shown below.

PDB1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = ol6-121.localdomain)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = pdb1)
    )
  )

PDB users with the SYSDBA, SYSOPER, SYSBACKUP, or SYSDG privilege can connect to a closed PDB. All other PDB users can only connect when the PDB is open. As with regular databases, the PDB users require the CREATE SESSION privilege to enable connections.

Data Pump Connections (expdp, impdp)

Connections to the expdp and impdp utilities are unchanged, provided you specify a service.

expdp username/password@service ...
expdp \"username/password@service as sysdba\" ...

impdp username/password@service ...
impdp \"username/password@service as sysdba\" ...

Connections as SYSDBA must be to a common user. For example.

expdp scott/tiger@pdb1 tables=EMP,DEPT directory=TEST_DIR dumpfile=EMP_DEPT.dmp logfile=expdpEMP_DEPT.log
expdp \"sys/SysPassword1@pdb1 as sysdba\" tables=EMP,DEPT directory=TEST_DIR dumpfile=EMP_DEPT.dmp logfile=expdpEMP_DEPT.log
expdp \"c##myuser/MyPassword1@pdb1 as sysdba\" tables=EMP,DEPT directory=TEST_DIR dumpfile=EMP_DEPT.dmp logfile=expdpEMP_DEPT.log