Virtual Databases within a Container Database

Oracle 12c introduces a new MultiTenant option for  Plugable Databases wherein a particular instance can host not only other databases as usual but entire separate virtual Oracle Homes. Oracle 12c supports older non CDB and PDB (Pluggable Databases) with the MultiTenant CDB ('super' Container Database).

PDBs are fully compatible with pre 12c older architecture non CDBs.  Typically a PDB will hold a single application back end.  From the OS standpoint the CDB is the database.  Each CDB wil be at a particular Oracle Database patchset level that is inherited by all included PDBs in the container (CDB) which greatly simplifies Oracle Patching Management by the DBA.

PDBs can be unplugged from a CDB and plugged into another CDB.  Data Guare Backup and other operations for a CDB carry along all PDBs automatically - greatly simplifying such operations and saving DBA time and effort.

The new multitenant architecture is available in Standard Edition, in Standard Edition One,and Enterprise Edition.

Implementation of schema-based consolidations accomplish within-database virtualization. Multitenant architecture provides intrinsic virtualization and a horizontally partitioned data dictionary.  Refer to the Oracle White Paper for an in-depth discussion of the new architecture.