Can I Change the Replication Mode Between RDS Primary Instances and Read Replicas?

For the MySQL and MariaDB engine:
A read replica uses a single-node architecture (without a standby node). Changes to the primary DB instance are also automatically synchronized to all associated read replicas through the native MySQL or MariaDB replication function. The synchronization is not affected by network latency. Even if a DB instance does not have a primary key ID, its data is synchronized to the associated read replicas.

The replication mode displayed on the RDS console indicates the data synchronization method between primary and standby DB instances. Semi-synchronous (default) and asynchronous are both supported. The semi-synchronous mode is more secure but the asynchronous mode improves performance.

The default synchronization between primary DB instances and read replicas is asynchronous and cannot be changed.
For the PostgreSQL engine:
Both asynchronous (default) and synchronous replication between the primary and standby instances are supported.
- Asynchronous replication is recommended for applications requiring a guarantee of high availability.
- Synchronous replication is recommended for applications that require strong data consistency and can tolerate a short-time blocking of write operations.
The asynchronous-commit mode is supported between primary instances and read replicas and cannot be modified.
For the Microsoft SQL Server engine:
The synchronous-commit mode is supported between primary and standby instances and cannot be modified.

The asynchronous-commit mode is supported between primary instances and read replicas and cannot be modified.

For more information, see official documentation.