Cross Store Support

Sometimes you need to store data in multiple data stores, and these data stores need to be of different types. One might be relational while the other is a document store. For this use case, we created a separate module in the MongoDB support that handles what we call “cross-store support”. The current implementation is based on JPA as the driver for the relational database and we let select fields in the Entities be stored in a Mongo database. In addition to letting you store your data in two stores, we also coordinate persistence operations for the non-transactional MongoDB store with the transaction life-cycle for the relational database.