How do i get to know when I fail to enter a duplicate database entry?

[Chin Shah]

I'm using Spring Data JPA with Hibernate.

I have a class with a composite key mapped to a database table.

When I perform a save operation using the JPARepository extended interface object, I see the following log in the console:

Hibernate: select rolefuncti0_.functionalityId as function1_4_0_, rolefuncti0_.roleId as roleId2_4_0_ from RoleFunctionality_Mapping rolefuncti0_ where rolefuncti0_.functionalityId=? and rolefuncti0_.roleId=?
Hibernate: insert into RoleFunctionality_Mapping (functionalityId, roleId) values (?, ?)

This is what I see when i repeat the operation with the same data:

 Hibernate: select rolefuncti0_.functionalityId as function1_4_0_, rolefuncti0_.roleId as roleId2_4_0_ from RoleFunctionality_Mapping rolefuncti0_ where rolefuncti0_.functionalityId=? and rolefuncti0_.roleId=?

It appears Spring Data first checks whether the Key exists in the database, and then proceeds to perform insertion.

There should be a way to catch the information which hibernate has found (that the database entry/key exists in the database)? How can we check that? There should be some kind of information which would be possible to get from Spring that it would return/give in any other way to the application- if it is not going to go ahead with insertion in the event of a duplicate entry. (Spring makes a decision (based on some information) not to insert after finding an existing primary key.)