Oracle Database 12c : Multitenant Architecture : Container or Pluggable Database CDB/PDB

 
 

Oracle_Database_MultiTenant_Architecture_PDB_CDB

With the launch of database 12c in 2013, Oracle introduced a new architectural concept called Multi-Tenancy, where you have a Container Database (CDB) and Pluggable Database (PDB).

To explain I included video from Tom Kyte & Randy Urbano where Tom discuss about Pluggable Databases and challenges in Database Consolidation. Randy explains Architecture of PDB/CDB and moves PDB from one CDB to another using SQL > ALTER PLUGGABLE DATABASE ….

Quiz (post answer under comments) : How many PDBs can be inside a CDB (hint watch the video) ?

Before running the Installer on an Linux environment, packages (RPMs) can be installed through yum to meet all the system per-requisites:

For Oracle Linux 6 yum install oracle-rdbms-server-12cR1-preinstall

For Oracle Linux 5 – yum install oracle-validated -y

Database software Installer and DBCA are similar to 11g, except for this screen where you can pre-configure your CDB and PDBs:

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This DBCA execution will not only create a CDB and 1 PDB, but a “seed pluggable database” as well .  You can use this seed database as a template to create other pluggable databases (PDBs).

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By default, after running the DBCA, all CDBs and PDBs are up and running.

You must be having some basic questions after reading Oracle Database Multi-Tenancy Architecture. So here are the answers.

  • Is there a difference when starting the listener and the CDB?

No!  You can start the listener and your CDB in exactly the same way as you did with your pre-12c database.

  • How can you connect to the CDB?

Very simple: just the same as in past with pre-12c databases.

$ sqlplus system@<CDB_db_name>

SQL*Plus: Release 12.1.0.2.0 Production on Sat Feb 27 09:13:31 2016

Copyright (c) 1982, 2014, Oracle. All rights reserved.

Enter password:
Last Successful login time: Tue Feb 23 2016 15:18:49 +00:00

Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 – 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

  • Are the PDBs opened by default, when starting the CDB?

No.  This can be verified by SQL from view v$pdbs:

SQL> select open_mode from v$pdbs where name='<PDB_db_name>′;

OPEN_MODE
———-
MOUNTED

The PDB is mounted; to open it, just run this command:

SQL> alter pluggable database <PDB_db_name> open read write;

Pluggable database altered.

SQL> select open_mode from v$pdbs where name='<PDB_db_name>′;

OPEN_MODE
———-
READ WRITE

Note: this must be done as “SYSDBA”.

  • How can we connect to the PDB?

There are 2 methods:

First method: connect to the CDB and then switch to the PDB by setting the container:

$ sqlplus system@<CDB_db_name>

SQL> show con_name

CON_NAME
——————————
CDB$ROOT
SQL> alter session set container=<PDB_db_name>;

Session altered.

Second method: Modify your tnsnames.ora file by adding an entry for the PDB, based on the CDB entry.

Now you can connect as usual to the PDB:

$ sqlplus system@<PDB_db_name>

As you can see, it is all quite easy.  One of the main benefits of this architecture is that you can handle every PDB as a separate database that can be upgraded or plugged/unplugged independently from other databases.

Oracle DBA 12c Interview Question

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This post is from our Oracle Database 12c Training where We cover Architecture, Installation, File System, Backup and Recovery and difference in 12c from previous version with Hands-On,  If interested in learning Oracle Database 12c you can Register here for Oracle Database 12c Training 

(There are limited early bird discount 50% OFF so if you are keen to learn and get trained on Oracle 12c Database as DBA then register for this course).

Series Navigation<< Why Fresher Oracle DBA Doesn’t Get Interview Calls ? Interview Questions for Oracle DBA 12cFive New Features in Oracle Database 12c for DBAs : Part1 >>

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This entry is part 2 of 4 in the series Oracle Database 12c

About the Author Nancy Kamboj

Oracle Consultant at K21 Technologies - Oracle Gold Partner specialising in Design, Implement, and Support.

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