The Database Migration Service of the Amazon Web Service (DMS AWS) is a cloud-based data migration service that facilitates database movement between on-premises servers to the cloud or from one cloud provider to another. It is also an optimized service for moving data between relational databases, data warehouses, and NoSQL databases. The only condition is that at least one of the source and the target databases should be operating in the cloud.

There are several benefits of using DMS AWS.

• No stoppage in work: During database migration with DMS AWS, the source database remains functional at all times and organizations do not have to resort to any downtime. This is a big help for large data-driven businesses for whom stopping systems even for brief periods can badly impact operating schedules.

• User-friendly migration: Data migration with DMS AWS is a simple user-friendly activity. Unlike traditional data migration processes, there is no need to install additional drivers and applications as the migration activity can be automatically initiated with a few clicks on the AWS Management console. There is no human intervention too at any point in the activity.

• Cost-effective: For database migration, users have to pay only for the quantum of computing and storage resources used. No flat fees regardless of what is used are charged, thereby saving substantial amounts.

• Support to databases: DMS AWS supports common databases and commercially-used applications thereby making migration between SQL, NoSQL, and text-based targets quick and easy.   

• Dependable migration: DMS AWS continually monitors the source and the target databases during migration and in case of any disruption, the process is resumed once the glitches are resolved.

The Database Migration Service also facilitates combining several databases into one target database.

Among the main functions of DMS AWS is to replicate data with high availability continually and consolidate databases into petabyte-scale warehouses. This is done by streaming data to Amazon S3 or Amazon Redshift.

There are two types of database migration with DMS AWS.

The first is Homogeneous Migration done when the database engines, data schemas, types, and structures of the source and the target databases are similar. Migration, in this case, is a simple one-off affair, and whole databases are moved in one shot. Examples of Homogeneous Migration are Oracle to Amazon RDS for Oracle, MySQL to Amazon Aurora, MySQL to Amazon RDS for MySQL, or Microsoft SQL Server to Amazon RDS for SQL Server.

The second is Heterogeneous Migration done when the key parameters unlike the first method are different. Hence, migration is a two-step activity as first, the schema structure and the data types and codes of the source database have to be transformed to match that of the target database. Once this is completed, migration is carried out as in the first method. Examples are Oracle to Amazon Aurora, Oracle to PostgreSQL, or Microsoft SQL Server to MySQL migrations.