Table A.E.51.1 - cab ride

Please build the Aggregation Path Array and assume the following end-user requirement:

1) "a daily report of each combination of driver and customer independent of the car"

2) "a roll-up by the time dimension starting at month for each type of car"

Select the corresponding cells in the APA and choose a cube to materialize, then highlight the derivatives of this cube.

Figure A.E.51.1 - The resulting APA with the redundancy free-set highlighted

Size of the redundancy-free set (including the base cube): 108

Required cubes, the materialization decision and derivatives

The blue area represents the end-user requirement 1 ("a daily report of each combination of driver and customer independent of the car") and the end-user requirement 2 ("a roll-up by the time dimension starting at month for each type of car").

Materializing cube v = (D_dr, Cu_cu, Ca_*, T_d) (dark blue cell "T_m", representing end-user requirement 1) and cube w = (D_*, Cu_*, Ca_ty, T_m) (dark green cell "T_y", representing end-user requirement 2) offer us the following sets of derivatives.

Figure A.E.51.2 - Derivatives of cube v = (D_dr, Cu_cu, Ca_*, T_d)

Figure A.E.51.3 - Derivatives of cube w = (D_*, Cu_*, Ca_ty, T_m)

Figures A.E.51.2 to A.E.51.3 show that no end-user requirement is covered by the derivatives of another vector. To meet all end-user requirements we will have to materialize both cubes, v and x.