How does AWS Database Migration Service (DMS) work?

AWS Database Migration Service (DMS) is a fully managed service that helps you migrate databases to AWS with minimal downtime. It works by creating a replication instance that reads data from the source database and writes it to the target database. The process has three phases: full load, change data capture (CDC), and final cutover. During the full load phase, DMS copies all existing data. In the CDC phase, it captures ongoing changes (inserts, updates, deletes) and applies them to the target, keeping the two databases in sync. Finally, at cutover, you switch your application to point to the target. DMS supports homogeneous migrations (e.g., MySQL to MySQL) and heterogeneous migrations (e.g., Oracle to PostgreSQL) by using source‑to‑target mapping rules and transformation logic. It handles schema conversion, data type mapping, and can run continuously with zero‑downtime replication, making it suitable for large, mission‑critical migrations.