Oracle Multitenant is the architecture for the next-generation database cloud. It delivers isolation, agility and economies of scale. A multitenant container database can hold many pluggable databases. An existing database can simply be adopted with no application changes required. Oracle Multitenant fully complements other options, including Oracle Real Application Clusters and Oracle Active Data Guard.
The many pluggable databases in a single multitenant container database share its memory and background processes. This enables consolidation of many more pluggable databases compared to the old architecture, offering similar benefits to schema-based consolidation but with none of the major application changes required by that approach.
Creating pluggable databases, moving pluggable databases between containers, and cloning pluggable databases are done with new SQL commands and take just seconds. When the underlying file system supports thin provisioning many terabytes can be cloned almost instantaneously simply by using the keywords “snapshot copy” in the SQL command.
The investment of time and effort to patch one multitenant container database results in patching all of its many pluggable databases. To patch a single pluggable database, you simply unplug/plug to a multitenant container database at a different Oracle Database software version.
To upgrade all hosted pluggable databases in a container database, simply upgrade the container database and all hosted pluggable databases are upgraded 'in-place'. To upgrade a single PDB, you simply unplug/plug the pluggable database in to a container database at a higher version and upgrade the pluggable database as described in the Database Upgrade Guide.
By consolidating existing databases as pluggable databases, administrators can manage many databases as one. For example, tasks such as backup and disaster recovery are performed at the multitenant container database level.
In Oracle Database 12c, Resource Manager is extended with specific functionality to control the competition for resources between pluggable databases within a multitenant container database.