1. A computer-implemented method for automated generic and parallel aggregation of characteristics and key figures of mass data, the mass data including M records from a single database of a single data source or from different databases of different data sources, particularly associated with financial institutions and with financial affairs in banking practice, and further including sets of rows and sets of columns, each row corresponding to a record, and the columns including fields of predetermined granularity characteristics and fields of predetermined key figures, wherein the aggregation reduces the amount of data to N≦M records for a customer defined granularity, the method comprising the following steps: receiving the mass data from a single database of a single data source or from different databases of different data sources associated with banking practice; selecting predetermined granularity characteristics and predetermined key figures, and selecting predetermined aggregation operations to be carried out by the processing means of a data processing system; reading input data from a single database of a single data source or from different databases of different data sources into the processing means of a data processing system; preparing the input data as data packages being of the size M p in a preparational step before the aggregation starts; processing the data packages being of the size M p in a parallel process by identifying the granularity characteristics, thereby identifying unique granularity levels i; sorting the records of each data package for a given order of granularity characteristics of the customized granularity; and subsequently aggregating the records in each data package for key figures by using aggregation operations; and following the aggregation, saving the results of each data package.