I am trying to determine the impact of implementing FKs within the database (Oracle 11g) after the Hibernate object relational mappings have been created. The relationships were supposedly already correctly mapped within Hibernate. The situation stems from an implementation inconsistency - most FKs (~500) were implemented within the database, but at some phase of the project the team stopped implementing FKs within the database. At the present time ~200 FKs remain unimplemented, but documented (column comments) within the database.

My present role is as DBA. I would like to implement these FKs within the database, but I have been lead to believe that implementing them now will break the application. I was specifically told that the application would not even start if I implemented the FKs, I am very skeptical.

I understand that there could be problems if the Hibernate relation mapping does not match to the FKs that would be implemented, but that would seem to me to cause run-time errors (SQLException?) of some sort.

Can anyone explain the real impact of implementing the FKs now?

Thanks for your time.