NHibernate HiLo - new column per entity and HiLo catches

I'm currently using the hilo id generator for my classes but have just been using the minimal of settings eg ``` <class name="ClassA"> <id name="Id" column="id" unsaved-value="0"> <generator class="hilo" /> </id> ... ``` But should I really be specifying a new column for NHibernate to use foreach entity and providing it with a max lo? ``` <class name="ClassA"> <id name="Id" column="id" unsaved-value="0"> <generator class="hilo"> <param name="table">hibernate_unique_key</param> <param name="column">classA_nexthi</param> <param name="max_lo">20</param> </generator> </id> ... <class name="ClassB"> <id name="Id" column="id" unsaved-value="0"> <generator class="hilo"> <param name="table">hibernate_unique_key</param> <param name="column">classB_nexthi</param> <param name="max_lo">20</param> </generator> </id> ... ``` Also I've noticed that when I do the above the SchemaExport will not create all the columns - only classB_nexthi, is there something else I'm doing wrong.