Hibernate transaction duplicate problem

Question

Hi every one, I want update some of my table in database and want all of these work do in 1 transaction, first of all I delete some entry in branchbuildin(Table) and Insert new one after this action The problem occurred when I insert and entry with same buildingname and branch_fk (be cause I have this constraint on this table ( uniqueConstraints={@UniqueConstraint(columnNames={"buildingname","branch_fk"})})) but when I don't use hibernate session and use normal JDBC transaction I don't have these problem.

List<Integer> allBranchBuilding = branchBuildingDao.getAllBranchBuildingID(pkId, sess);
            for (Integer integer : allBranchBuilding) {
                branchBuildingDao.delete(integer, sess); // delete kardane tamame BranchBuilding ha va tel haie aanha
            }

            Address myAdr = new Address();
            setAddress(myAdr, centralFlag, city, latit, longit, mainstreet, remainAdr, state);
            BranchBuildingEntity bbe = new BranchBuildingEntity();
            setBranchBuildingEntity(bbe, be, myAdr, city, centralFlag, latit, longit, mainstreet, buildingName, remainAdr, state, des);
            branchBuildingDao.save(bbe, sess);//Exception Occurred

I get my session at the first of Method:

        Session sess = null;
        sess = HibernateUtil.getSession();
        Transaction tx = sess.beginTransaction();

Answer 1

You're right, everything occurs in the same transaction, and the same Hibernate Session.

The Session keeps track of every entity it manages. Even though you asked to delete it in the database, the corresponding object is still memorised in the Session until the Session is terminated.

In general, it is possible that Hibernate reorders your operations when sending them to the database, for efficiency reasons.

What you could do is flush (ie. send to the database) your transaction because the save (if needed, you could also clear - ie empty the entities memorized by the Session - it after flushing):

sess.flush();
// sess.clear(); // if needed or convenient for you
branchBuildingDao.save(bbe, sess);

Note also that while your entities are memorized by the session, modifying them will trigger an automatic update when closing the session.

In our project, we have a method that deletes efficiently a collection (and another for an array, declared using the convenient ... parameter syntax) of entities (it works for all entities, it doesn't have to be done for each entity), removing them out of the session at the same time, and taking care of the flushing before :

1. Loop on all entities, delete it (using sess.delete(e)) and add it to a 'deleteds' list.
2. Every 50 entities (corresponding to the batch size we configured for efficiency reasons) (and at the end) :
   • flush the Session to force Hibernate to send immediately the changes to the database,
   • loop on 'deleteds' list, clear each entity from the Session (using sess.evict(e)).
   • empty the 'deleteds'list.

Don't worry, flush only sends the SQL to the database. It is still subject to commit or rollback.