Standalone Rails Migrations

Posted by Tejus Parikh on August 17, 2009

One of the most annoying things about deployments are dealing with databases. In the Java world, using Hibernate to generate your schema is pretty common. It works well in development, where you generally re-create and re-seed your database after each model change. However, it can be disastrous when deploying. It felt like each sprint needed a dedicated day for diff-ing the database schemas and figuring out what changed and what needed to be applied. Often, indexes would be forgotten, resulting in un-foreseen slowness.

Ruby on Rails solves that problem with using migrations. Migrations describe how to move from one version of the database to the next. While it’s built into Rails, I came across Standalone-migrations on GitHub. Not surprisingly, it exposes the core functionality of Ruby on Rails migrations, allowing you to embed it in any kind of project. You’ll still need Ruby to run the migrations along with the correct gems for connecting to the database.

Of course, Ruby on Rails migrations have a few downsides. Personally, I believe that the database should be aware of constraints and relationships. This has other practical benefits, such as automatic indexes. By default, Rails Migrations do not support foreign key’s natively. Simon Harris wrote a plugin to automatically associate foreign keys. Way easier than writing SQL.

Getting a rails plugin to work standalone required some munging, so I ham-fisted Standalone Migrations and Foreign Key Migrations together and put the project on GitHub. If this is something you need, clone my fork of Standalone Migrations.

Tejus Parikh

Tejus is an software developer, now working at large companies. Find out when I write new posts on twitter, via RSS or subscribe to the newsletter: