Greetings. Maybe I'm missing something but I'm really surprised that Hibernate is not reporting a constraint violation on insert, only when I call commit. At that point I may have inserted a number of records and I have no idea what the offending one was. Thoughts?

Details:
Java 6, Hibernate Core 3.3.1 GA.

Related code snippets:
Session session = sessionFactory.getCurrentSession();
tx = session.beginTransaction();
...

//bean is a JPA-annotated class. Why can't I get a violation notification right here, while saving?
session.save(bean);
...
tx.commit();


Call stack:
org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:94)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:114)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:109)
at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:244)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2252)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2688)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:79)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:167)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1027)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:365)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)
.......

In order to know the cause of constraint violation you can enable Hibernate log like this:
log4j.logger.org.hibernate.util.JDBCExceptionReporter=error

Hibernate now logs all failures related to JDBC in the console.

Hibernate uses transaction-level write-behind mechanism which fires DML statements on transaction commit. This makes sense because this way locks used by database to execute DML statements are kept for as short time as possible.

Thank you for the responses. Now I understand why im not getting violations on save.
I added:
log4j.logger.org.hibernate.util.JDBCExceptionReporter=error

to my log4j.properties but still I'm not seeing any primary key IDs being included in the exception.

Also, with errors only being thrown on commit, how can I reject the offending record and commit the rest? I.e. I let's say don't want to reject the whole batch just because of one corrupt record in batch.
I heard that the spring batch framework allows you to do that easily but... I don't want to reach for spring batch at the moment.