Hi

I'm dealing with an existing Oracle DB which has two tables looking like :
PARENT ( ID, NAME, .... )
CHILD ( ID, PARENT_ID, NAME, ... )

CHILD.PARENT_ID column has a Foreign Key on PARENT.ID colum with the "On Delete Option" which allows to delete directly entries in PARENT without having to delete explicitely linked entries in CHILD table - Oracle will do it automatically


(the creating scripts looks like :

alter table CHILD
add constraint FK_PARENT_ID foreign key (PARENT_ID)
references PARENT_ID (ID)
on delete CASCADE

)

)

On Java side, I've got so far something like:


public class ChildDTO implements Serializable {
...

@ManyToOne
@JoinColumn(name = "parent_id")
@MapsId("id")
private ParentDTO parent;

...
}




public class ParentDTO implements Serializable {
...

@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<ChildDTO> childs;

...
}


When deleting an ParentDTO objects, ChildDTO objects related to the ParentDTO are deleted to.
But I can also observe on Oracle side that Hibernate sends a DELETE requests on the table CHILD, though it's not necessary since the "On Delete Cascade" option of my FK make Oracle delete CHILD whenever it's PARENT_ID does not exists anymore in the PARENT table.
So I would like to know the correct option to set , so as Hibernate wont send the DELETE requests on CHILD table anymore, while still handling correctly the ParentDTO <> ChildDTO relationship.

So far I tried this other setting with no success :
@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = false)
(apparently not correct on Java side)
and
@OneToMany(mappedBy = "parent", cascade = {CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH, CascadeType.PERSIST}, orphanRemoval = true)
(didn't seem to change anything)

Thanks in advance!

OK, I finally found the solution in a book.
The annotation @OnDelete(action= OnDeleteAction.CASCADE) tells Hibernate that the DBMS is doing the cascade and therefore that Hibernate shoud only care of his side.

Here is the ParentDTO with the annotation :


public class ParentDTO implements Serializable {
...

@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
@OnDelete(action= OnDeleteAction.CASCADE)
private Set<ChildDTO> childs;

...
}