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. In RDS for Oracle, PDBs are referred to as tenant databases. Your client applications connect at the tenant database (PDB) level rather than the CDB level. RDS for Oracle supports the following configurations of the CDB architecture:
- Multi-tenant configuration
-
This RDS platform allows an RDS for Oracle CDB instance to contain between 1–30 tenant databases, depending on the database edition and any required option licenses. You can use RDS APIs to add, modify, and remove tenant databases. The multi-tenant configuration in RDS for Oracle doesn't support application PDBs or proxy PDBs, which are special types of PDBs. For more information about application PDBs and proxy PDBs, see Types of PDBs
in the Oracle Database documentation. Note
The Amazon RDS configuration is called "multi-tenant" rather than "multitenant" because it is a capability of the RDS platform, not just the Oracle DB engine. Similarly, the RDS term "tenant" refers to any tenant in an RDS configuration, not just Oracle PDBs. In the RDS documentation, the unhyphenated term "Oracle multitenant" refers exclusively to the Oracle database CDB 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.
Note
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:
