Oracle Pluggable Databases; aka Multitenant

Pluggable databases were one of the new features of 12c. All Oracle databases before Oracle Database 12c were non-CDBs. Oracle has termed “multi-tenancy” to describe the process of creating a CDB that contains many “tenant” PDB’s. Starting at 12c, this was available as a paid Enterprise Option called Multitenant (NUP $350, Processor $17,500). The multitenant architecture enables an Oracle database to function as a multitenant container database (CDB). A CDB includes zero, one, or many customer-created pluggable databases (PDBs). Multitenant is Oracle’s Cloud Database Architecture.

What’s New(ish):

Prior to 19c (or 18 XE), you were only allowed to have a single user-defined pluggable database (plus a root container and a proxy) without having to license the full multitenant option. Oracle has announced that, from 19c onward, you can have 3 user-defined PDBs, without having to license the multitenant option.

According to Oracle; “For all offerings, if you are not licensed for Oracle Multitenant, then you may have up to 3 user-created PDBs in a given container database at any time.” Link

There are a number of benefits to pluggable databases:

  • Database consolidation. Starting in Oracle Database 12c, the Oracle Multitenant option enables you to consolidate data and code without altering existing schemas or applications. This represents a potential 300% consolidation factor from a database standpoint.
  • Cost reduction. By consolidating hardware and database infrastructure to a single set of background processes, and efficiently sharing computational and memory resources, you reduce costs for hardware and maintenance.
  • Easier management and monitoring of the physical database
  • Secure separation of administrative duties
  • Separation of data and code
  • Easier and more rapid movement of data and code
  • Ease of performance tuning
  • Support for Oracle Database Resource Manager
  • Easier and quicker cloning
  • Easier database upgrades as well as fewer patches and upgrades


  • In version 20c the non-CDB architecture will be desupported. The 20c upgrade will include a migration to the multitenant architecture.


Pluggable Databases is the direction of Oracles’ future. Enterprise database consolidation can lead to greater scalability and improved resource utilization and response time, which could reduce server and storage hardware costs while increasing throughput. Multitenant architecture retains the separation of individual databases and should require no changes to applications, it should also simplify DBA tasks such as cloning, tuning, patching, and upgrading.

Companies should analyze their environment, and create a cost benefit analysis to determine any return on investment (ROI) of investing time, effort, and money in the Multitenant paid option, or upgrading to 19c sooner than planned.


Imagine being able to reduce your Oracle footprint. By consolidating Oracle Database servers, organizations could reduce their Oracle database, options and pack footprint by up to 300%. As a best/worst case scenario example, simply from a licensing perspective, in an extremely unconsolidated mixed vendor environment, the client could take advantage of the “3 user-created PDBs in a given container database” to reduce their potential server hardware needs from 3 database servers down to potentially 1 Oracle database server, this would cut their Oracle initial license exposure by up to 66%.

Cost wise, in this example, a common database server might require running Oracle Database, Diagnostics, and Tuning. Licensing for 3 servers (common server specs – Six-Core AMD Opteron Processors, 8 processors per server) might cost a client as much as $3.4 million in initial licenses and support costs (35% discount). Assuming the client could take advantage of pluggable databases, in an extreme worst case of un-consolidated server scenario, reducing the 3-database servers down to 1 consolidated Oracle database server, would help the client avoid over $2.2 million in initial Oracle licensing purchases. The ROI in this hypothetical and extreme case would be the $2.2 million, plus the annual Oracle support year after year which could be over $400k annually.

Who should consider Pluggable databases?

  1. Companies with large environments with unconsolidated servers can take advantage of pluggable databases to reduce their database footprint and for better resource utilization, and shared resource management.
  2. Companies with high overhead and maintenance costs, can potentially take advantage of the reduced database management possibilities of multitenant. Manage many as one.
  3. Companies that already have plans to move to version 19c.

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