Abstract: Computer-implemented method for allocating columns of a table stored in a database system into at least two sets of columns, a first set and a second set, the data of the columns allocated to the first set being stored on a primary storage medium using a column-oriented data structure and the data of columns allocated to the second set being stored on a secondary storage medium using a row-oriented data structure, wherein the method comprises the step of allocating the columns of the table to the first and the second set autonomously on the basis of a performance-cost model.