Major Description
If the dimension number in an aggregation group exceeds the number of "kylin.cube.aggrgroup.max.size" (default 12), Kylin will throw an error saying "Aggregation group <n> has too many dimensions"; User has to remove some dimensions to proceed.
This check adds up the number of mandantory dimensions, hierarchy, joint and normal dimensions; This is too strong. The check should be optimized, all mandantory be treated as 1; all joint dimensions be treated as 2; each hierarchy be treated as N+1; nomal dimensions be 2^N; Control total combination numbers no more than a configured value ("kylin.cube.aggrgroup.max.combination", default 4096).