"Schema SPY". Schema Spy allows you to generate the metadata about the database and all sorts
of statistics that are helpfull at a glance. It supports multiple databases to generate the schema documentation of course if you are a java developer it should be more simpler, to get this configuration working.
You may optionally need a graphical library to draw the relationships called graphviz.
Other dependencies are to have the driver jar files in the class path and execute the schema spy jar from the command line.