Studierende stehen vor dem LC und blicken lächelnd einer Kollegin mit einer Mappe in der Hand nach.

Exercise No. 21: Soccer Goal (apa)

As the result of DFM Case "soccer goal" this cube stores data about soccer goals.

We have four dimensions with the following hierarchical structure (parallel hierarchy!):

Table A.E.33.1 - soccer goal

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

1) "a roll up by the time dimension starting at months for each nationality independent of all other dimensions"

2) "an annual report for each combination of soccer team and referee, irrespective of all other dimensions"

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

Solution

Figure A.E.33.1 - The resulting APA with the redundancy free-set highlighted

Size of the redundancy-free set (including the base cube): 256

Required cubes, the materialization decision and derivatives

The blue area represents the end-user requirement 1 ( "a roll up by the time dimension starting at months for each nationality independent of all other dimensions") and requirement 2 ("an annual report for each combination of soccer team and referee, irrespective of all other dimensions").

Materializing cube v = (S_*,R_*,P_na,ST_*,T_m) (dark blue cell "R_*", representing end-user requirement 1) and cube w = (S_*,R_re,P_*,ST_st,T_y) (dark green cell "T_y", representing end-user requirement 2) offer us the following sets of derivatives.

Figure A.E.33.2 - Derivatives of cube v = (S_*,R_*,P_na,ST_*,T_m)

Figure A.E.33.3 - Derivatives of cube w = (S_*,R_re,P_*,ST_st,T_y)

Figures A.E.33.2 and A.E.33.3 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 w.

This exercise is part of a case study: dfm - apa - log