RDS for Oracle database architecture - Amazon Relational Database Service
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RDS for Oracle database architecture

The Oracle multitenant architecture, also known as the CDB architecture, enables an Oracle database to function as a multitenant container database (CDB). A CDB can include customer-created pluggable databases (PDBs). A non-CDB is an Oracle database that uses the traditional architecture, which can't contain PDBs. For more information about the multitenant architecture, see Oracle Multitenant Administrator’s Guide.

For Oracle Database 19c and higher, you can create an RDS for Oracle DB instance that uses the CDB architecture. Your client applications connect at the PDB level rather than the CDB level. RDS for Oracle supports the following configurations of the CDB architecture:

Multi-tenant configuration

This RDS platform feature allows an RDS for Oracle CDB instance to contain between 1–30 tenant databases, depending on the database edition and any required option licenses tenant databases (PDBs). The multi-tenant configuration doesn't support application PDBs or proxy PDBs. You can use RDS APIs to add, modify, and remove tenant databases.


The Amazon RDS feature is called "multi-tenant" rather than "multitenant" because it is a capability of the RDS platform, not just the Oracle DB engine. The term "Oracle multitenant" refers exclusively to the Oracle database architecture, which is compatible with both on-premises and RDS deployments.

Single-tenant configuration

This RDS platform feature limits an RDS for Oracle CDB instance to 1 tenant database (PDB). You can't add more PDBs using RDS APIs. The single-tenant configuration uses the same RDS APIs as the non-CDB architecture. Thus, the experience of working with a CDB in the single-tenant configuration is mostly the same as working with a non-CDB.

You can convert a CDB that uses the single-tenant configuration to the multi-tenant configuration, thus allowing you to add PDBs to your CDB. This architecture change is permanent and irreversible. For more information, see Converting the single-tenant configuration to multi-tenant.


You can't access the CDB itself.

In Oracle Database 21c and higher, all databases are CDBs. In contrast, you can create an Oracle Database 19c DB instance as either a CDB or non-CDB. You can't upgrade a non-CDB to a CDB, but you convert an Oracle Database 19c non-CDB to a CDB, and then upgrade it. You can't convert a CDB to a non-CDB.

For more information, see the following resources: