NHibernate генерирует инструкцию обновления для всех столбцов

Does NHibernate always generate update for all columns?

public class Person
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string Address { get; set; }
}

Person p = Session.Load(1);
p.Name = "New Name";

Session.Flush();//Update for all columns, but I change only Name

Is it normal behavior for NHibernate or my mistake? I use Fluent NHibernate and AutoMapping.