Database Versioning with Ladder Migrations

Version control systems are invaluable for tracking changes in your code, particularly when you’re working in a team. However, most applications don’t consist solely of application code. Managing changes to the database has always been a little more challenging, particularly when you’re adding new features which require changes to the schema.

Suppose you’re working on a module and realize one of the database tables needs an additional column. You might be tempted to open up a database query tool or the command line and simply add the column. However, this doesn’t leave a record of the change in the same way as version-controlled application code would. This gets exacerbated when working in a team - if a colleague pulls your code changes without running those same database updates, then it’s entirely possible their version of the application will break. This becomes even more problematic when you’re releasing a product update, when it could break the application not just for your fellow developers, but for your users.

One solution is to move responsibility for creating and modifying the database schema into code, using migrations. That way, changes can be managed along with the rest of your application, and features we take for granted in version control - such as being able to compare versions and keep an audit trail - can be used for database changes. It also allows these changes to be seamlessly incorporated into releases, since they can be made part of the same branch or tag.

Many major frameworks have their own migration implementation, but for those that don’t - and if you’re not using any framework - there’s Ladder.

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