Oracle 12c New features – Multitenant Database

In this article we will 12c features related to Multitenant Database

12c database Support both non-CDB and CDB architecture and Multitenant architecture can work on Oracle RAC as well as on  Active Data Guard.

 

Understanding Why Multitenant database?

Below are few reason to know reason behind using Multitenant database 

Cost reduction

     Reduce capital expenses

     Reduce hardware footprints

     Reduce operating cost (license, maintenance, monitor)

Easy provisioning

     Easier and rapid movement of data and code and separation of code

     Easy to plug and unplug database across same and different servers

Database consolidation

Easy to manage

     Easy migration and testing

     Easy to monitor, maintain and backed up

     Quicker environment refresh activities

     Less administration work related to database Patching and better security control than normal pre-12 databases
     Ease of performance tuning
     DR configuration

Next point comes in mind that What is pluggable database?

Definition: Simple meaning is Many database in single database - Multiple Pluggable databases (PDBs) in single Container Database (CDB) acts like separate database even though they shares the physical as well as logical structures.

Terminologies to Remember 

Root Container - Like a meta database (CDB$ROOT) which stores the system metadata required to manage PDBs. 

Container – This is Logical structure which is collection of schemas, object and related structures in CDB that appears as a separate database to application

  

Container database(CDB )- SYS is common schema in CDB which owned all PDBs.  Every CDB has Control files, Redo log files, Undo tablespace, Global temporary tablespace, SYSTEM &  SYSAUX tablespace along with any additional tablespace.

Pluggable database (PDB)- which is user created set of schemas and objects. PDB isolated data and operation and must be uniquely named within a CDB.  PDBs shares control files, redo logs, undo and global temporary tablespace from CDB whereas PDBs have their own SYSTEM tablespace, SYSAUX tablespace, Local temporary and individual Application tablespaces. maximum 252 PDBs are allowed in single instance.

Common between CDB and PDB's

-Background processes
-Redo logs- these are common for entire database (Container)
-Memory
-Control  files
-Global Temp tablespace
-undo tablespace
-network admin files like listener.ora, tnsnames.ora, sqlnet.ora etc.
-SGA

Individual for PDB's

-Separate SYSTEM and SYSAUX tablespace
-Individual tablespaces or datafiles
-Local temp tablespace
-Local users and local roles
-Local metadata of PDB's
-PDB resource manager

(Also  read- User creation in 12c and clone remote PDB using database link )

Keep watching more is coming on Oracle 12c