Have you ever longed for a way of making the delivery of databases more visible, predictable and measurable? Do you ever wish that they would be of better quality, quicker to change, and cost less? Grant Fritchey explains some of the secrets of doing Continuous Integration for Databases to relieve some of the pain-points of the Database Delivery process.

Continuous Integration (CI) is an essential step of application development for DevOps organisations. Whenever a developer commits code, a build is kicked off. The code must compile and pass automated testing before it is merged into the main branch. Developers have been working this way for years, but including the database in CI has lagged behind. Leaving the database out of CI has caused it to become the bottleneck that slows down the delivery of new features. Even though it’s more difficult to execute, many organizations have successfully implemented database CI with the right tools.

The purpose of Database CI is exactly the same as for application CI. The development team establish a working version of the database very early in the development cycle, and then continue to verify regularly that it remains in a working state as they expand and refactor the schema and database code objects. Developers integrate new and changed code into a shared version control repository several times a day. Development proceeds in small steps. Developers first write the tests that, if passed, will prove that a small new piece of functionality works. They then implement the code to make the tests pass. When the tests pass, they commit the code to “trunk” in the shared VCS, and their “commit tests” are added to the broader suite of tests for the application. Each commit, or check-in, is then verified by an automated database build or migration, and subsequent testing, allowing teams to detect problems early.

Where do you start with database CI? There are several requirements outlined here.

Maintain the database in version control

The first prerequisite for Database CI is that the source of “truth” for the database CI process and all subsequent database deployments must be the build and migration scripts in a version control system (VCS), such as Git or Subversion. In other words, the database CI process must always be triggered from the VCS. There must be no ad-hoc builds or database modifications that bypass this formal process.

There are several CI management software services available. Each one I’ve worked with has hooks into various version control systems. With these hooks you can set up mechanisms for automating your database CI processes.

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