SUM measure return type should not overflow

Currently, the SUM measure return type is the same with original table column type, that would not work if the original table column has very limit digit capability. Take an example, the original column type is decimal(1,0), if we SUM on this column, the result will be overflow soon.

Proposal: Define the return type much more clear. If the original column type is decimal with decimal point, no matter what the precision digit is, define the return type as decimal(19,4). If the original column type has no decimal point，define the return type as decimal(14,0). If the original column is integer family, the return type would be bigint.