An apparatus, a method, and a computer program product for obtaining map update data of a region are provided. The method comprises receiving a node identifier and a first node digest of an update candidate node; obtaining, based on the node identifier, a second node digest of the update candidate node; comparing the first node digest and the second node digest of the update candidate node; and generating, based on the comparison, the update data for the map database, the update data containing one of an indication of unchanged content; node digests of the child nodes of the update candidate node; or updated content corresponding to the update candidate node.