Interlude – database migrations

For quite some time in the world of application development, we used a variety of tools to track and record code-related changes over time. Generally, these fall under the umbrella of version control systems, or VCS, and there are many of them to choose from: Git, Mercurial, Subversion, Perforce, Darcs, and several others. Each system functions in a slightly (or not so slightly) different manner, but they all have the same goal of preserving point-in-time snapshots of a codebase (or portions of a codebase, depending on the tool being used) so that it can be recreated at a later time.

One aspect of web applications that is generally difficult to capture and track is the current state of the database. In the past, we made do by storing entire SQL snapshots along with the application code and would instruct developers to drop and recreate their database. The next level of improvement on this would be the creation of small SQL-based scripts that should be run in...