code: func FullIntRange(isUnsigned bool) []*Range {
  	if isUnsigned {
  		return []*Range{{LowVal: []types.Datum{types.NewUintDatum(0)}, HighVal: []types.Datum{types.NewUintDatum(math.MaxUint64)}}}
  	}
  	return []*Range{{LowVal: []types.Datum{types.NewIntDatum(math.MinInt64)}, HighVal: []types.Datum{types.NewIntDatum(math.MaxInt64)}}}
  }
docs: // FullIntRange is used for table range. Since table range cannot accept MaxValueDatum as the max value.
  // So we need to set it to MaxInt64.