Database migration is always a complex task, and it must be evaluated, validated, and executed carefully. The AWS Database Migration Service deals with all of the complexity of executing a replication, multi-engine job via a migration instance, and keeps the origin and destination databases in sync. DMS can be used to migrate existing OLTP and OLAP workloads into the AWS cloud.

DMS can be used for one-time and ongoing live migrations with zero downtime. Multiple databases (shards) can be consolidated into a single, master database. This results in a lot of flexibility for service-oriented architectures, like microservices and database federation patterns.

If your migration can be done with downtime, the simplest strategy is to use vendor tooling to perform the activity, like .bak files, pg_dump, or textual logic dump files (.sql). You can select which tables, schemas, or databases to replicate on a per-job basis.

If the migration cannot tolerate service downtime, you must consider the use of DMS. You must also do the same for other use cases like transformations between engines and cross-region replication in regions where this service feature is not available.