EntityManager.createNativeQuery and SELECT ... FOR UPDATE

Stefan Arentz · **Joined:** Mon Nov 22, 2004 10:38 am **Posts:** 9

Can anyone enlighten me whether this is a valid usage of createNativeQuery?

My problem is simple. I have some JPA code that basically needs to do this:

Code:

begin transaction;
select * from A, B where A.b_id = B.id and A.id = 123 for update;
update A ...;
update B ...;
commit;

I moved this from a stored procedure to Java code by doing something like this:

Code:

BeginTransaction();
{
   A a = entityManager.createNativeQuery("select * from A where .. for update", A.class).setParameter(...).getSingleResult();
  a.setFoo(123);
  a.getB().setBar(456);
  entityManager.merge(a);
}
CommitTransaction();

This seems to work fine, but I am not sure if this is really allowed. I first tried to do this with only native queries, including for the updates, but that resulted in things being out of sync with the cache. So i ended up with this combination of a native select and 'jpa updates'.

Anyone any thoughts? Just looking for some feedback.

S.

emmanuel · **Posted:** Fri Aug 18, 2006 5:59 pm

This is valid but somehow useless.
A a = entityManager.getReference(A.class, a.getId() );
entityManager.lock( a, LockModeType.READ );

Will do the same (or use the optimistic locking mechanism of a version is available).

session/lock has an even more fine grained locking scheme