Migrating Databases to the Amazon Web Services Cloud Using the Database Migration Service - Database Migration Guide
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Migrating Databases to the Amazon Web Services Cloud Using the Database Migration Service

You can use several Amazon tools and services to migrate data from an external database to Amazon. Depending on the type of database migration you are doing, you may find that the native migration tools for your database engine are also effective.

Amazon Database Migration Service (Amazon DMS) helps you migrate databases to Amazon efficiently and securely. The source database can remain fully operational during the migration, minimizing downtime to applications that rely on the database. Amazon DMS can migrate your Oracle data to the most widely used commercial and open-source databases on Amazon.

Amazon DMS migrates data, tables, and primary keys to the target database. All other database elements are not migrated. If you are migrating an Oracle database to Amazon Aurora MySQL-Compatible Edition, for example, you would want to use the Amazon Schema Conversion Tool in conjunction with Amazon DMS.

The Amazon Schema Conversion Tool (Amazon SCT) makes heterogeneous database migrations easy by automatically converting the source database schema and a majority of the custom code, including views, stored procedures, and functions, to a format compatible with the target database. Any code that cannot be automatically converted is clearly marked so that it can be manually converted. You can use this tool to convert your source Oracle databases to an Amazon Aurora MySQL, MySQL, or PostgreSQL target database on either Amazon RDS or EC2.

It is important to understand that Amazon DMS and Amazon SCT are two different tools and serve different needs.

  • Amazon DMS takes a minimalist approach and creates only those objects required to efficiently migrate the data for example tables with primary key. Therefore, we will use DMS to load the tables with data without any foreign keys or constraints. (We can also use the SCT to generate the table scripts and create it on the target before performing the load via DMS).

  • We use Amazon SCT:

    • To identify the issues, limitations and actions for the schema conversion

    • To generate the target schema scripts including foreign key and constraints

    • To convert code such as procedures and views from source to target and apply it on target

The size and type of Oracle database migration you want to do greatly determines the tools you should use. For example, a heterogeneous migration, where you are migrating from an Oracle database to a different database engine on Amazon, is best accomplished using Amazon DMS. A homogeneous migration, where you are migrating from an Oracle database to an Oracle database on Amazon, is best accomplished using native Oracle tools.

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