We put the latest Apache Syncope and PostgreSQL on the bench to try and push to the limit: here are the results
Federations in MS SQL Azure are a way to achieve greater scalability and performance from the database tier of your application through horizontal partitioning. One or more tables within a database are split by row and portioned across multiple databases (Federation members).
HSQLDB is a very nice and complete all-Java DBMS, particularly useful when doing quick test-outs or maven tests. A while ago, a bug has been discovered in release 2.0.0 that is causing issues with BLOB management: this is a considerable issue especially with @Lob fields in Hibernate.