Re: Difference between commit and flush in Hibernate

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 27 May 2007 22:02:27 -0400

Message-ID:

<465a3823$0$90269$14726298@news.sunsite.dk>

santax wrote:

Could you please tell me the difference between commit(method of
Session) and flush(method of Transaction) in Hibernate?

It is my understanding that flush causes Hibernate to execute
SQL statements via JDBC while commit end up as a database
commit. Two completely different things.

I have read that one should use FlushMode.AUTO and never care
about flush, but my experience with Hibernate is not sufficient
to comment on whether that is good or bad advice.

  I read the book "Java Persistence with hibernate" which reference
to DAO Pattern for JDK1.5.
  The main interface of the pattern is GenericDAO as below:

  public interface GenericDAO<T, ID extends Serializable> {
         T findById(ID id, boolean lock);
         List<T> findAll();
         List<T> findByExample(T exampleInstance,
         String... excludeProperty);
         T makePersistent(T entity);
         void makeTransient(T entity);
         void flush();
         void clear();
}

what me me puzzled is why it has no method commit? And when should I
call the method flush and when shuold I commit the transaction if I
use this pattern?

I have not read the book, so it is hard for me to say.

But it makes sense to me that commit is not tied to a specific
DAO, because a transaction will often be covering multiple
types of DAO's.

And when you call commit should be determined by your
business logic.

Arne