1. A computer-implemented method for automated generic and parallel aggregation of characteristics and key figures of data associated with financial institutions and with financial affairs in banking practice, the method comprising: receiving, at a data processing system, mass data from a single database of a single data source or from different databases of different data sources, the mass data comprising a plurality of records, the records being associated with granularity characteristics and key figures; selecting, according to a customer-defined aggregation, granularity characteristics of the received mass data, key figures of the received mass data, and aggregation operations associated with the key figures; generating a plurality of data packages from the received mass data, the data packages comprising a plurality of records, the plurality of records of the data packages being smaller than the plurality of records of the received mass data; processing, using a processor of the data processing system, the data packages to reduce a number of records in the data packages according to the customer-defined aggregation, wherein the processing comprises: identifying a granularity level associated with the selected granularity characteristics, the identified granularity levels defining an order of the selected granularity characteristics; sorting the records of the data packages according to the defined order of granularity characteristics; aggregating the sorted records of the data packages for the selected key figures using the selected aggregation operations, the aggregation reducing the records of the data packages; and identifying adjacent data packages by comparing, for the aggregated data packages, a key of a first record of the aggregated data packages with a key of a first record and a key of a last record of the other aggregated data packages, the identifying comprising: computing termination criteria for pairs of the aggregated data packages, the termination criteria having the form: 
 key pos1,x ε(key pos1,y ;key posmax:y ), wherein pos 1 represents a first position of a data package, posmax represents a last position of a data package, and x and y represent numbers of data packages; and identifying adjacent packages based on a violation of corresponding ones of the termination criteria, the adjacent data packages having first record keys that are closest together; and saving, to a memory of the data processing system, the aggregated records of the data packages, wherein the stored records comprise fewer records than the received mass data at the customer-defined granularity.