When migrating your Microsoft SQL Server database using AWS DMS, you can choose to migrate existing data only, migrate existing data and replicate ongoing changes, or migrate existing data and use change data capture (CDC) to replicate ongoing changes. Migrating only the existing data does not require any configuration on the source SQL Server database. However, to migrate existing data and replicate ongoing changes, you need to either enable MS-REPLICATION, or MS-CDC.
In this step you are going to execute a .sql script that will configure the source database for replication
Replication requires a primary key for all tables that are being replicated. If your tables don’t have primary keys defined, consider using MS-CDC instead.