Implementation of Bottom-Up Cubing Algorithm for Iceberg Cubes, Beyer et al, SIGMOD 99.
Assumes Measure is monotonically increasing i.e. M(A union B) >= M(A)
Successively sort and partition data by columns, aborting sort if partition's aggregate doesn't meet threshold, since it's sub-partitions will apriori not meet threshold either.
#License 3-clause BSD.