How can you manage database schema changes during Azure SQL Database migration?

1 Assess your source schema

Before you start the migration, you need to assess your source schema and identify any potential issues or incompatibilities with Azure SQL Database. You can use tools such as Data Migration Assistant (DMA) or SQL Server Data Tools (SSDT) to analyze your source schema and generate reports on the compatibility level, feature parity, and migration blockers. You can also use these tools to compare your source and target schemas and detect any differences or conflicts.

2 Plan your schema changes

Once you have assessed your source schema, it's important to plan how to apply the schema changes to your target database. You can choose to apply the changes manually, using scripts or tools, or automatically, with continuous integration and delivery (CI/CD) pipelines. The decision depends on your migration strategy, the complexity and frequency of the changes, and the level of automation and testing you desire. When considering this, factors such as the order and timing of the changes, the impact and risk of each change on performance, availability, and security of your database, as well as rollback and recovery options must be taken into account. It is essential to ensure that the changes are applied in the correct sequence and at the right time to avoid breaking dependencies or causing data loss. Additionally, it is wise to have a backup and restore plan in place in case something goes wrong and you need to revert the changes or recover your data.

3 Use schema comparison tools

A schema comparison tool, such as SSDT or Visual Studio Code, is an invaluable tool for managing schema changes. It enables you to compare two schemas, either from source and target databases or from project files, and generate a script or report that displays the differences and the steps required to synchronize them. By using a schema comparison tool, you can validate the schema changes before applying them to the target database, detect and resolve any conflicts or errors that may occur during migration, update the source or target schema to reflect the latest modifications, and track and document the schema changes for auditing and compliance purposes.

4 Use source control and versioning

Another best practice for managing schema changes is to use source control and versioning systems, such as Git or Azure DevOps. These systems enable you to store, manage, and track the changes to your schema files in a centralized repository. This allows you to collaborate and coordinate with other developers or teams working on the same database project, review and approve the schema changes before merging them to the main branch, create and deploy different versions of your schema for different environments, and restore or rollback to a previous version of your schema in case of errors or issues.

5 Use CI/CD pipelines

If you want to automate and streamline your schema changes, you can take advantage of CI/CD pipelines like Azure DevOps or GitHub Actions. These pipelines will help you build, test, and deploy your schema changes to the target database in a reliable manner. You can use CI/CD pipelines to integrate the schema changes from the source control and versioning system, run unit tests and code analysis, deploy the schema changes with SSDT or Azure Data Factory, and monitor and troubleshoot the schema changes with Azure Monitor or Application Insights. Managing database schema changes during Azure SQL Database migration can be daunting, but with the right tools and practices, you can ensure a successful migration. By assessing, planning, comparing, controlling, and automating your schema changes, you can guarantee that your database is up-to-date, compatible, and secure.