Function GetResultType

be/src/runtime/decimal-test.cc:746–778

Implementation of decimal rules. This is handled in the planner in the normal execution paths.

// Implementation of decimal rules. This is handled in the planner in the normal
// execution paths.
ColumnType GetResultType(const ColumnType& t1, const ColumnType& t2, Op op, bool v2) {
  // TODO: Implement V2 result types
  switch (op) {
    case ADD:
    case SUBTRACT:
      return ColumnType::CreateDecimalType(
          max(t1.scale, t2.scale) +
              max(t1.precision - t1.scale, t2.precision - t2.scale) + 1,
          max(t1.scale, t2.scale));
    case MULTIPLY:
      return ColumnType::CreateDecimalType(
          t1.precision + t2.precision, t1.scale + t2.scale);
    case DIVIDE:
      if (v2) {
        int result_scale =
            max(ColumnType::MIN_ADJUSTED_SCALE, t1.scale + t2.precision + 1);
        int result_precision =t1.precision - t1.scale + t2.scale + result_scale;
        return ColumnType::CreateAdjustedDecimalType(result_precision, result_scale);
      } else {
        return ColumnType::CreateDecimalType(
          min(ColumnType::MAX_PRECISION,
            t1.precision - t1.scale + t2.scale + max(4, t1.scale + t2.precision + 1)),
          min(ColumnType::MAX_PRECISION, max(4, t1.scale + t2.precision + 1)));
      }
    case MOD:
      return ColumnType::CreateDecimalType(
          min(t1.precision - t1.scale, t2.precision - t2.scale) + max(t1.scale, t2.scale),
          max(t1.scale, t2.scale));
    default:
      EXPECT_TRUE(false);
      return ColumnType();
  }
}

TEST(DecimalTest, ResultTypes) {
  ColumnType t1 = ColumnType::CreateDecimalType(38, 10);