As we discussed on Irc but for posterity. EntityKey represents what you need to reach an entity. It contains both the actual id information and the metadata necessary to do the query. Likewise, we have AssociationKey that does represent an association navigation. RowKey is used to represent two things: - each entry key in an association navigation (which is conceptually a map) - the unique identifier to reach a sequence or a table generator entry I tend to like the fact that these are typed differently so in a way I'd split the RowKey in two more than merge everything together. If anything it makes is easier for a GridDialect writer to understand what's going on. Davide pointed out that a common super interface might be useful in a couple of places. Emmanuel On 8 nov. 2013, at 13:20, Gunnar Morling wrote: