AWS Database Migration Service
User Guide (Version API Version 2016-01-01)

Migration Methods for AWS Database Migration Service

AWS Database Migration Service can migrate your data in several ways:

  • Migrating Data to the Target Database – This process creates files or tables in the target database, automatically defines the metadata that is required at the target, and populates the tables with data from the source. The data from the tables is loaded in parallel for improved efficiency. This process is the Migrate existing data option in the AWS console and is called Full Load in the API.

  • Capturing Changes During Migration – This process captures changes to the source database that occur while the data is being migrated from the source to the target. When the migration of the originally requested data has completed, the change data capture (CDC) process then applies the captured changes to the target database. Changes are captured and applied as units of single committed transactions, and several different target tables can be updated as a single source commit. This approach guarantees transactional integrity in the target database. This process is the Migrate existing data and replicate ongoing changes option in the AWS console and is called full-load-and-cdc in the API.

  • Replicating Only Data Changes on the Source Database – This process reads the recovery log file of the source database management system (DBMS) and groups together the entries for each transaction. If AWS DMS can't apply changes to the target within a reasonable time (for example, if the target is not accessible), AWS DMS buffers the changes on the replication server for as long as necessary. It doesn't reread the source DBMS logs, which can take a large amount of time. This process is the Replicate data changes only option in the AWS DMS console.


If you restart a task, any tables that have not completed their initial load are restarted.