⟩ What is data sparsity and how it effect on aggregation?
Data sparsity is term used for how much data we have for a particular dimension/entity of the model.
It affects aggregation depending on how deep the combination of members of the sparse dimension make up. If the combination is a lot and those combination do not have any factual data then creating space to store those aggregations will be a waste as a result, the database will become huge.