So I’m pretty sure I’ve found a bug.
Add the attached test to FooBarTests.cs

1 Run it as it is and it works.
2 Modify the code by adding ! before SHOULDNT_THIS_BE_ENOUGH (that is choose the Evict solution).

It seems that even if I’ve re-read the One instance getting it to understand that its version (V) is 1, 0 is used in the update statement. The 0 was the original value when first reading the instance. Run the code.

Regards, Ingo

[Test]
public void IsThisABug()
{
long key;
using (ISession s = OpenSession())
{
One one = new One();
one.Manies = new HashedSet();
s.Save(one);
s.Flush();
key = one.Key;
}

// Intending to update
ISession s1 = OpenSession();
One o1 = (One)s1.Get(typeof(One), key);
Assert.IsNotNull(o1);
Assert.AreEqual(0, o1.V);

// Update in another session beats u to it
ISession s2 = OpenSession();
One o2 = (One)s2.Get(typeof(One), key);
Assert.IsNotNull(o2);
o2.X = 2;
s2.Flush();
Assert.AreEqual(1, o2.V);
s2.Dispose();

// slow as I am, now I'm gonna try to update
o1.X = 1;
try
{
s1.Flush();
Assert.Fail("Should fail");
}
catch(NHibernate.StaleObjectStateException)
{
// oh, well. Prepare to retry
#if SHOULDNT_THIS_BE_ENOUGH
s1.Evict(o1);
#else
s1.Dispose();
s1 = OpenSession();
#endif
}

// let's read it from db again and retry the update
o1 = (One)s1.Get(typeof(One), key);
Assert.AreEqual(1, o1.V);
o1.X = 1;
// with Evict, this fails again with StaleObjectStateException
// note that o1.V == 1 is however correct with Evict
s1.Flush();
Assert.AreEqual(2, o1.V);

s1.Dispose();

using (ISession s = OpenSession())
{
s.Delete( "from o in class NHibernate.DomainModel.One" );
s.Flush();
}
}

I'm so sorry. I ended up in the wrong forum with this post. I ment to post in NHibernate.
Once again, sorry.
/ingo