There are some resources on the architecture and the internals of Derby. They can be found under the 'Papers and Presentations' section .
Dear Moderator,I have found that the issue on Derby MERGE statement is still not resolved. ( link: https://issues.apache.org/jira/browse/DERBY-3155 )So I can work on this matter as I know concepts of DBMS.I already download and build the source code of Derby using eclipse. I have read some documentation about the Derby. but they provide only about how to use derby but not about the architectural view about Derby. Can you please add me to the Derby mailing list so I can get some help from the developers.If you can send me some links and information about how I will start my work to implement this method.Thank you.--
Adeesha Wijayasiri.Undergraduate,Department of Computer Science & Engineering,University of Moratuwa.