Different bahaviour between MySQL and Oracle after persist and select

Hibernate ORM
1

I like to persist an entity and want to select it from the database. If I do this with mysql, it is working, if I do it in Oracle it is not working. So I have the following Code:

EntityManager em = emf.createEntityManager();
em.setFlushMode(FlushModeType.COMMIT);
em.getTransaction().begin();
Anrede anrede = new Anrede();
anrede.setBezeichnung("Test");
System.out.println("persist");
em.persist(anrede);
System.out.println("anrede id: " + anrede.getId());
List<Anrede> anreden = em.createQuery("from Anrede a where a.bezeichnung='Test'").getResultList();
if (anreden.isEmpty())
	System.out.println("Notfound");
for (Anrede anrede1 : anreden) {
	System.out.println("found: " + anrede1 + " " + anrede1.getBezeichnung());
}

If I run the code with MySQL, I get the follwing output:

persist
Hibernate: insert into anrede (version, bezeichnung) values (?, ?)
anrede id: 26
Hibernate: select anrede0_.id as id1_7_, anrede0_.version as version2_7_, anrede0_.bezeichnung as bezeichn3_7_ from anrede anrede0_ where anrede0_.bezeichnung='Test'
found: Anrede [id=26] Test

If I run the code with Oracle, I get the follwing output:

persist
Hibernate: select hibernate_sequence.nextval from dual
anrede id: 7858215
Hibernate: select anrede0_.id as id1_7_, anrede0_.version as version2_7_, anrede0_.bezeichnung as bezeichnung3_7_ from anrede anrede0_ where anrede0_.bezeichnung='Test'
Notfound

The difference between MySQL and Oracle is that Oracle uses a sequence to generate the ids and MySQL uses column identity. In the output u see that mysql is running the insert query and oracle is not running the insert query, it is only selecting the next ID from the sequece.

If I debug Hibernate I see that MySQL uses the class EntityIdentityInsertAction with the method isEarlyInsert that returns true
and Oracle uses the class EntityInsertAction with the method isEarlyInsert that returns false.
If I change the EntityInsertAction class that the method isEarlyInsert returns true then it works as aspected, but I dont think it is a good Idea to change the hibernate code, that could break other thinks.

Anyway the code shows a different behavior if I’m using differnt Databases. Is it possible to configure Hibernate in Orcale to use “EarlyInserts”?

I could flush the entitymanger or use the FlushModeType.AUTO to have allmost the same behavior, but then I’m getting huge Performance Issues.
I’m using Hibernate 5.6.15.
Can someone help me out?

2

I could flush the entitymanger or use the FlushModeType.AUTO to have allmost the same behavior, but then I’m getting huge Performance Issues.
I’m using Hibernate 5.6.15.
Can someone help me out?

Well, you are using non-default settings i.e. FlushModeType.COMMIT, so it is expected that there might be such issues. I don’t know what sort of performance issues you think you are getting, but the difference in behavior is because your id generation (@GeneratedValue) uses the AUTO strategy. On MySQL this will use default to IDENTITY and on Oracle to SEQUENCE.

You can change the setting to @GeneratedValue(strategy = IDENTITY) if you want the same behavior on all databases.