Discuss the difference in storage requirements for a data cube implemented as a multidimensional array and a fact table.

What will be an ideal response?

If the data cube has m dimensions, and the attribute in the jth dimension can take on nj values (e.g., there are 100 markets in the market dimension), the complete description of that cube in a multidimensional array or a fact table would take n1 ? n2 ? ... ? nm storage locations. However, if some items are missing (e.g. Market 10 had no sales of Product 4 in the time period T4), that rowcan be omitted from the fact table, but the space has already been allocated in the array. Thus in practice the fact table is considerably smaller than the multidimensional array.