Oracle RDS Architecture

When you create an RDS for Oracle 19c instance, AWS provides you with options for both the traditional standalone architecture (non-CDB) and the multitenant architecture (CDB with PDBs).

For Oracle Database 19c on Amazon RDS, you can choose to create either:

1. A non-CDB instance: This is a traditional standalone Oracle database that doesn't use the container database architecture.

2. A CDB instance with PDBs: This uses the multitenant architecture, where the database functions as a container database (CDB) that includes one or more pluggable databases (PDBs).

If you opt for the multitenant architecture, Amazon RDS for Oracle supports two configurations:

1. Single-tenant configuration: The CDB contains only one tenant database (PDB).

2. Multi-tenant configuration: The CDB can contain between 1-30 tenant databases (PDBs), depending on the database edition and required option licenses.

When creating your RDS for Oracle 19c instance, you'll need to specify whether you want to use the multitenant architecture and which configuration you prefer. The choice between these options depends on your specific requirements for database consolidation, resource utilization, and management needs.

It's worth noting that starting from Oracle Database 21c, the multitenant container database is the only supported architecture in Amazon RDS for Oracle. However, for 19c, you still have the flexibility to choose between the traditional standalone architecture and the multitenant architecture.
Sources
RDS for Oracle database architecture - Amazon Relational Database Service
Get started with the Multi-Tenant feature of Amazon RDS for Oracle | AWS Database Blog
Oracle multi-tenant architecture - AWS Prescriptive Guidance
Amazon RDS for Oracle now supports Oracle Multitenant

AWS RDS for Oracle version 19c offers both the options: multi-tenant architecture as well as standalone instance. You can tick checkbox for "Oracle multitenant architecture" given on AWS RDS console when you create the RDS Oracle Instance on 19c if you want to go with Oracle multitenant architecture .

There is a switch [--multi-tenant | --no-multi-tenant] in AWS CLI as well when you create RDS Oracle instance via CLI to choose the desired architecture.

Reference: ++ https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Oracle.Concepts.CDBs.html ++ https://aws.amazon.com/blogs/database/get-started-with-the-multi-tenant-feature-of-amazon-rds-for-oracle/ ++ https://docs.aws.amazon.com/cli/latest/reference/rds/create-db-instance.html

When creating your RDS for Oracle 19c instance, you'll need to specify whether you want to use the multitenant architecture and which configuration you prefer. The choice between these options depends on your specific requirements for database consolidation, resource utilization, and management needs.

Starting from Oracle Database 21c, the multitenant container database is the only supported architecture in Amazon RDS for Oracle. However, for 19c, you still have the flexibility to choose between the traditional standalone architecture and the multitenant architecture.

One thing to note, for Oracle Database 19c and 21c, Amazon RDS supports a subset of multitenant architecture called the single-tenant configuration, and separately full multi-tenant is also supported. When you create the instance, the architecture is a permanent characteristic that you can't change later.