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 subscription for a client, wherein the surrogate keys include values to be used by the client to account for an inability to access a key creation process, and wherein the list includes child mobile business objects (MBOs) referenced by parent MBOs that are expected to be on the client upon completion of a synchronization; determining a set of deleted surrogate keys that the client currently has that are no longer in the list of unique surrogate keys that should currently be part of the 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.