Agile Database Migration Tools for Java

Agile methodologies of software development require a major shift in approach towards database management. The reason is requirements are never really frozen during agile development. Though changes are controlled, the attitude of the process is to enable change as much as possible. This change can be in response to the inherent instability of requirements in many projects or to better support dynamic business environments.

Thus agile development needs tools to enable and support evolutionary database design, along with solving problems like porting database schema changes on an instance with critical data.

Ruby on Rails, which is designed for agile development, provides built-in capabilities to cope with this problem, in the form of Active Record Migration. However, Java currently doesn’t have a solution of that pedigree. There are a few viable alternatives though, the most popular among the current breed is Liquibase. I will present an evaluation here which might help you choose the best tool.

Liquibase: Here are my observations, from trying to integrate it with a Spring, Hibernate3 annotation based configuration project. Liquibase is described as a substitute for Hibernate’s hbm2ddl. It can be integrated with an existing project in a few simple steps. The advantages are Spring integration so dev environments have updated databases. Secondly version management – changesets are ID-ed and stored in a table after being applied to a database and changelogs can be written in SQL.

Liquibase gives 2 ways of writing migrations, XML based and SQL based. The biggest disadvantage of Liquibase is the inability to write java-based migrations. This lead us to a search for a solution that provides most of the features present in Liquibase, as well as support for Java-based migrations.

c5-db-migration: c5-db-migration supports migrations in Groovy, as well as migrations from within the application i.e. it provides APIs for migrations. However it doesn’t support migrations written in Java. There is no multiple schema support and it isn’t present in maven central.

Migrate4j: This tool supports Java migrations and it also provides an API for migrations. Disadvantage is that it doesn’t support even plain SQL migrations and is terribly short on features (no auto creation of metadata table, no multiple schema support and no maven support).

Flyway: Flyway offers cleaner versioning than Liquibase, migrations can be written in Java as well as SQL, and it supports auto-discovery of migrations in project packages.  However the one missing feature is that it doesn’t support rollbacks, though it is more of a design choice taken by Flyway developers.

After careful evaluation of each of these tools we decided to go ahead with Flyway for the project, and it has been great so far.

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