I have been doing a lot of work with Java. A lot of it in getting the     C++ and Java interfaces to align. So when I went looking for a database engine, I settled on H2 for the Java engine.

    Since you can run Raydo in an application, H2 can be run in an embedded mode, as well as HSQLDB and Derby. It can also be run as a client / server and a cluster.

The ‘plugin’ was added to the Java tree.
    So looking at the benchmarks, it seems that H2 is faster than HSQLDB & Derby in the embedded space, and comparable with Postgres and MySQL in the client/server space.