Abstract: A method in an aggregator server of synchronizing data records responsive to variable update notifications includes: receiving, from a provider system, an update notification corresponding to a master data object at the provider system; retrieving a record containing a local data object corresponding to the master data object; determining whether the update notification contains update definitions identifying changes to the master data object; selecting between a delta synchronization mode, when the determination is affirmative, and an object comparison synchronization mode, when the determination is negative; for the delta synchronization mode, updating the local data object according to the update definitions; for the object comparison synchronization mode, obtaining a copy of the master data object, and updating the local data object based on a comparison between the local data object and the copy of the master data object; and storing the updated local data object in the record at the aggregator.