I think we should leverage the locality information that is available in the path of an item and use this information also in the persistence layer. while sequential ids give you a hint when nodes were created, paths provide you a much better hint on locality. access patterns I've seen so far in applications are usually along the ancestor or descendant nodes axis.
This exposes another implicit assumption underlying 'sequential node ids': temporal locality implies spacial locality. This is not necessarily correct however.
Michael
