What would be the licensing model if the product is open source, but is NOT free (i.e., customers are charged for an open-source product in which BDB is used)?
(1) If people need to pay to use, it's not "open source" by the "open source definition" of the OSI: <http://www.opensource.org/docs/osd>;
(2) Contacting Oracle/BDB will let you know what they think your obligations are.