Thanks to Lothar Behrens
, I discover LiquiBase
a "an open source (LGPL), database-independent library for tracking, managing and applying database changes" (by database changes, they mean changes on the database schema).
LiquiBase offers version control support for database schemas and includes the possibility of checking the differences between two schema versions. For some schema changes, LiquiBase is even able to generate also the SQL script required to update the database data.