nhibernate : executing updates in batches

Question

I am trying to do batch updates using NHibernate, but it is not doing batch updates, its doing individual writes for all the rows. I have to write around 10k rows to db.

        using (var session = GetSessionFactory().OpenStatelessSession())
        {
            session.SetBatchSize(100);
            using (var tx = session.BeginTransaction())
            {
                foreach (var pincode in list)
                {
                    session.Update(pincode);
                }
                tx.Commit();
            }
        }

I have tried setting batch size to 100 using session.SetBatchSize(100); but that does not help. Also tried setting batch size using cfg.SetProperty("adonet.batch_size", "100"); but thats also not helping.

I am using GUID primary keys, hence I dont understand the reason for batch update failure. This is exactly the solution explained here. But its not working for me.

NOTE I have version field for optimistic concurrency mapped on all the entities. can that be the culprit for not having batch updates??

EDIT

i tried using state-ful session but that also did not help

        //example 2
        using (var session = GetSessionFactory().OpenSession())
        {
            session.SetBatchSize(100);
            session.FlushMode = FlushMode.Commit;
            foreach (var pincode in list)
            {
                session.Update(pincode);
            }
            session.Flush();
        }

       //example 3
        using (var session = GetSessionFactory().OpenSession())
        {
            session.SetBatchSize(100);
            using (var tx = session.BeginTransaction())
            {
                foreach (var pincode in list)
                {
                    session.Update(pincode);
                }
                tx.Commit();
            }
        }

example 2 for some reason is causing double round trips.

EDIT

after further research I found that, each session.Update is actually updating the db

        using (var session = SessionManager.GetStatelessSession())
        {
            session.SetBatchSize(100);
            foreach (var record in list)
            {
                session.Update(record);
            }
        }

how can I avoid that.

EDIT

tried with flush mode as well, but thats also not helping

        using (var session = SessionManager.GetNewSession())
        {
            session.FlushMode = FlushMode.Never;
            session.SetBatchSize(100);
            session.BeginTransaction();
            foreach (var pincode in list)
            {
                session.SaveOrUpdate(pincode);
            }
            session.Flush();
            session.Transaction.Commit();
        }

EDIT 4

even below one is not working, given i am fetching all entities in same session and updating and saving them in that session only...

        using (var session = SessionManager.GetSessionFactory().OpenSession())
        {
            session.SetBatchSize(100);
            session.FlushMode = FlushMode.Commit;
            session.Transaction.Begin();
            var list = session.QueryOver<Pincode>().Take(1000).List();
            list.ForEach(x => x.Area = "Abcd" + DateTime.Now.ToString("HHmmssfff"));
            foreach (var pincode in list) session.SaveOrUpdate(pincode);
            session.Flush();
            session.Transaction.Commit();
        }

Answer 1

nhibernate does not batch versioned entities that was the issue in my case.

There is no way you can batch version entities, the only to do this is to make the entity non versioned.