This pattern describes how you can migrate an on-premises Oracle database to either of the following PostgreSQL-compatible AWS database services with minimal downtime:
Amazon Relational Database Service (Amazon RDS) for PostgreSQL
Amazon Aurora PostgreSQL-Compatible Edition
The solution uses AWS Database Migration Service (AWS DMS) to migrate the data, AWS Schema Conversion Tool (AWS SCT) to convert the database schema, and an Oracle bystander database to help manage the migration. In this implementation, the downtime is restricted to however long it takes to create or validate all of the foreign keys on the database.
The solution also uses Amazon Elastic Compute Cloud (Amazon EC2) instances with an Oracle bystander database to help control the stream of data through AWS DMS. You can temporarily pause streaming replication from the on-premises Oracle database to the Oracle bystander to activate AWS DMS to catch up on data validation, or to use another data validation tool. The Amazon RDS for PostgreSQL DB instance or Aurora PostgreSQL-Compatible DB instance and the bystander database will have the same data when AWS DMS finishes migrating current changes.
