in one aspect , a method of storing data includes setting a first data node in a first storage area and setting a second data node in a second storage area . the second data node is an element of a plurality of elements forming a first flat table of at least one flat table in the second storage area . the step of setting a first data node includes storing in the first data node a two - tuple linker which comprises a first identifier indicating the first flat table and a second identifier indicating the row of the element in the first flat table . in another aspect a corresponding data storage structure is further provided .