Table A.E.45.1 - an accident

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

1) "a monthly report on the accident type level independent of all other dimensions"

2) "a roll up by the time dimension starting at months for each combination of accident type and district, independent of all other dimensions"

Select the corresponding cells in the APA and choose the cubes to materialize, then highlight the derivatives of those cubes.

Figure A.E.45.1 - The resulting APA with the redundancy free-set highlighted

Size of the redundancy-free set (including the base cube): 324

Required cubes, the materialization decision and derivatives

The blue area represents the end-user requirement 1 ("a monthly report on the accident type level independent of all other dimensions") and requirement 2 ("a roll up by the time dimension starting at months for each combination of accident type and district, independent of all other dimensions").

Materializing cube v = (DR_*,W_*,E_*,A_ty,D_*,T_m) (dark blue cell "D_*", representing end-user requirement 1) and cube w = (DR_*,W_*,E_*,A_ty,D_di,T_m) (dark green cell "A_ty", representing end-user requirement 2) offer us the following sets of derivatives.

Figure A.E.45.2 - Derivatives of cube v = (DR_*,W_*,E_*,A_ty,D_*,T_m)

Figure A.E.45.3 - Derivatives of cube w = (DR_*,W_*,E_*,A_ty,D_di,T_m)

Figures A.E.45.2 and A.E.45.3 show that end-user requirement 1 is covered by the derivatives of the vector w. To meet all end-user requirements we will only have to materialize cube w.