NHibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

I have an Class with property

[Serializable]
public class MyClass    {



    public MyClass    ()
    {
    }




    public virtual System.DateTime Time        {
        get;
        set;
    }


    public virtual string Name        {
        get;
        set;
    }

    public virtual string Department        {
        get;
        set;
    }

    public virtual string Ip
    {
        get;
        set;
    }


    public virtual string Address        {
        get;
        set;
    }


    public override bool Equals(object obj)
    {

        if (obj == null)

            return false;

        MyClass    t = obj as MyClass    ;

        if (t == null)

            return false;

        if (this.Time  == t.Time  && this.Name== t.Name && this.Department== t.Department)

            return true;

        else

            return false;

    }

    public override int GetHashCode()
    {

        int hash = 13;

        hash = hash +

          (null == this.Time ? 0 : this.Time.GetHashCode());

        hash = hash +

          (null == this.Name? 0 : this.Name.GetHashCode());

        hash = hash +

        (null == this.Department ? 0 : this.Department.GetHashCode());

        return hash;

    }
}

I am having my Nhibernate mapping as

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="NhibernateTest" assembly="NhibernateTest">
    <class name="MyClass" table="NhibernateTest">
        <composite-id>
            <key-property column="Time" type="DateTime" name="Time"></key-property>
            <key-property name="Name" type="string" column="Name" ></key-property>
            <key-property name="Department" type="string" column="Department" ></key-property>
        </composite-id>
        <property column="Ip" type="string" name="Ip" />
        <property column="Address" type="string" name="Address" />
    </class>
</hibernate-mapping>

I am trying to perform a bulk upload for some 40k data's with using composite key. using the following code.

    public void StoreInRDBMS(List<MyClass> FileList)
    {

       ITransaction transaction = null;
        try
        {     
            var stopwatch = new Stopwatch();

            stopwatch.Start();

            ISession session = OpenSession();
            using (transaction = session.BeginTransaction())
            {

                foreach (var File in FileList)
                {

                    session.SaveOrUpdate(File);



                }

                session.Flush();
                session.Clear();
                transaction.Commit();

            }

            session.Close();


            stopwatch.Stop();

            var time = stopwatch.Elapsed;





        }
        catch (Exception ex)
        {

            transaction.Rollback();

        }
    }

but the problem is , while iterating in the loop the second record in the list throws this error

{"a different object with the same identifier value was already associated with the session: NhibernateTest.MyClass, of entity: NhibernateTest.MyClass"} though the records are unique. and also if at all its not it should update the same.

It works file if I flush the session after every iteration in the loop like

                foreach (var File in FileList)
                {

                    session.SaveOrUpdate(File);

           开发者_开发问答         session.Flush();
                    session.Clear();


                }

which should not be the case and even its talkin 17 mins for 40 k records if done by above method. Can anybody help regarding the same.

Maybe?

foreach (var File in FileList)
                {

                    session.SaveOrUpdate(File);
                    session.ExecuteUpdate();


                }