Quick tip: automatically applying Liquibase changesets to HSQL

This is a quick tip for usage of Liquibase with HSQL. You may use the former tool for relational database schema migrations and the latter as in-memory database on the developers’ machines. Today, with feature branches and project customisation, i.e. changes that are specific for a single customer, you may have to shutdown the database, restart and reapply the migrations on a regular basis. Of course, this is a task that can be automated!

Typical situation: you are working on the project’s main development branch, but you now wish to review a colleague’s new feature, which has been developed in a feature branch. You switch to the feature branch, start the server, open the application and BAM, an exception occurs due a failed schema validation. The reason: your colleague made some schema changes in the feature branch that you forgot to apply.

Improving your Liquibase and HSQL workflow is rather simple: restart the database whenever the schema changes and apply the migrations! This is how you can do it in bash (sorry Windows users).

You need to make sure that you have two environment variables setup. There should be a variable PROJECT_REPO which points to the root directory of your project’s repository and M2_REPO which points to the Maven repository. You may also need to tweak a few paths, e.g. the version of HSQL that you are using as well as the Maven project and profile names. At last, you should install the inotify-tools (unfortunately not available on OS X). inotifywait (part of the inotify-tools) is used to watch the changelog directory for changes. The project’s Wiki has a section on installation .

Once setup, usage is pretty easy: start the script and let it do the rest. When the inotify-tools are not installed, you need to switch to your terminal and hit “the any key” in order to discard the current and apply a new schema.