1. A method comprising: mapping native attributes for a mobile business object (MBO) to a relational structure; building a list of unique surrogate keys that should currently be part of a client subscription, wherein the list includes child mobile business objects (MBOs) referenced by parent MBOs that are expected be on the client upon completion of a synchronization; determining a set of deleted surrogate keys the client currently has that are no longer in the list of surrogate keys that should currently be part of a client subscription; removing the deleted surrogate keys for the client from a client device database; updating a surrogate key list the client is expected to have; wherein the updating comprises: for surrogate keys the client already has, doing nothing; and for each new surrogate key the client does not yet have: inserting a row in the surrogate key list; and setting a timestamp indicating when the new surrogate key first became part of what the client is expected to have.