In data warehouse technology, a multiple dimensional view can be implemented by a relational database technique (ROLAP), or by a multidimensional database technique (MOLAP), or by a hybrid database technique (HOLAP).

(a) Briefly describe each implementation technique. 

(b) For each technique, explain how each of the following functions may be implemented: 

i. The generation of a data warehouse (including aggregation) 

ii. Roll-up

iii. Drill-down