Measures: Three Categories
distributive: if the result derived by applying the function to n aggregate values is the same as that derived by applying the function on all the data without partitioning.
- E.g., count(), sum(), min(), max().
algebraic: if it can be computed by an algebraic function with M arguments (where M is a bounded integer), each of which is obtained by applying a distributive aggregate function.
- E.g., avg(), min_N(), standard_deviation().
holistic: if there is no constant bound on the storage size needed to describe a subaggregate.
- E.g., median(), mode(), rank().