Issue link: https://resources.awscloud.com/i/1496544
Migrating Applications There are two basic strategies for moving your databases and related applications: Li and shi Move an entire database as is, with all of the applications it sup‐ ports, to the new database in the cloud. This is the "old wine in a new bottle" application migration strategy given that you make little or no use of cloud native features. Redesign the databases Rethink how your on-premises databases deal with administra‐ tive tasks such as scaling and high availability, and investigate the cloud provider's offerings in those areas. They are getting more and more sophisticated. More work and effort is required for this strategy, of course. You might also need to recode the applications to adjust to the changes in database strategy. Often, customers start with "lift and shift" and follow up with rede‐ signing and other modernizations. Post-Migration Checks After the data is completely copied over to the cloud database, vali‐ date the target database to ensure that all of the database objects are present on the cloud database. Several tests determine whether the migration was successful: Validate data This can be as simple as checking the number of rows, or run‐ ning a checksum to indicate that there was no loss or corrup‐ tion. More complex validation processes factor in the schema changes inherent in heterogenous migrations. Unfortunately, this basic validation is often forgotten. Basic functionality Perform end-to-end testing to ensure that you performed the migration successfully and that the system is operating as it is supposed to. Test the use of features that tend to differ between database engines and versions, such as triggers and stored pro‐ cedures. 34 | Chapter 3: Moving Your Databases to the Cloud