Abhinav and I were talking about Derby the other day, and I put together the following, which I thought was possibly interesting to others, too.
Apart from the bug that we are working on, is there any other resource/ documentationYes, definitely! In fact, there's so much, the big problem is knowing where to start.
There's all the manuals: Derby 10.11 Manuals.
If you haven't read through "Getting Started with Derby", that's the most important one to read at the beginning. It has a bunch of examples arranged a little bit like a tutorial that are good to get you going.
After a while, you're pretty comfortable running Derby, and you'like to know more about how it works.
For internals documentation, the most important resources are:Internals of Derby: An Open Source Pure Java Relational Database Engine.
Of course, there is the code, which can be tricky, but is very good to read. Anyone can read the code. You can download a source tarball, or check out a copy from Subversion.
Or you can use the Online ViewVC browser.
And another important resource is the JIRA database. Often, when I am trying to figure out how something works or why it is written the way it is, I end up looking at the Subversion history to learn about the history of the changes, and then looking in JIRA for a discussion of the change in question.