in an only stepwise update in that the segments are modeled to a hierarchical model in the decentralized database and in the updating of the segment the particular segments from which the segment depends are updated as well application_number US 30961707 A description the following representation is based on a navigation system however the present invention is not limited to navigation systems but may be used wherever updated data are required and have to be incorporated into a database the downloading of updated versions of games or application programs from the internet are mentioned as an example fig1 shows a data center 1 navigation databases are compiled within the data center the navigation databases include for example information about the road network or what is known as points of interest e g locations of gas stations hotels or landmarks data center 1 includes a data compiler 2 which collects and compiles data data compiler 2 collects data that are necessary or useful for a navigation database such as the aforementioned data about the road network from these data data compiler 1 composes updates 3 4 5 of the raw data of the navigation database in fig1 the three cylinders represent three updates 3 4 5 of the navigation database for three consecutive years each update 3 4 5 includes the entire data stock of raw data of the underlying navigation database changes in the data in.