Jailer: Database Subsetting and Sampling Tool.

If you use an enterprise application, you probably maintain full-size copies of the production database to meet development and testing requirements. Numerous copies are unnecessarily full-size as development and testing teams may only require relatively small samples of data to meet their objectives.

Jailer exports consistent, referentially intact row-sets from relational databases (exports data from production database and imports it into development database). It's also able to remove obsolete data without violating integrity.

It generates DbUnit datasets, hierarchically structured XML and topologically sorted SQL-DML.
http://jailer.sourceforge.net