Function LimitDecimalWidth

pkg/sql/sem/tree/decimal.go:53–87

LimitDecimalWidth limits d's precision (total number of digits) and scale (number of digits after the decimal point). Note that this any limiting will modify the decimal in-place.

(d *apd.Decimal, precision, scale int)

// (number of digits after the decimal point). Note that this any limiting will
// modify the decimal in-place.
func LimitDecimalWidth(d *apd.Decimal, precision, scale int) error {
	if d.Form != apd.Finite || precision <= 0 {
		return nil
	}
	// Use +1 here because it is inverted later.
	if scale < math.MinInt32+1 || scale > math.MaxInt32 {
		return errScaleOutOfRange
	}
	if scale > precision {
		return pgerror.Newf(pgcode.InvalidParameterValue, "scale (%d) must be between 0 and precision (%d)", scale, precision)
	}

	// http://www.postgresql.org/docs/9.5/static/datatype-numeric.html
	// "If the scale of a value to be stored is greater than
	// the declared scale of the column, the system will round the
	// value to the specified number of fractional digits. Then,
	// if the number of digits to the left of the decimal point
	// exceeds the declared precision minus the declared scale, an
	// error is raised."

	c := DecimalCtx.WithPrecision(uint32(precision))
	c.Traps = apd.InvalidOperation

	if _, err := c.Quantize(d, d, -int32(scale)); err != nil {
		var lt string
		switch v := precision - scale; v {
		case 0:
			lt = "1"
		default:
			lt = fmt.Sprintf("10^%d", v)
		}
		return pgerror.Newf(pgcode.NumericValueOutOfRange, "value with precision %d, scale %d must round to an absolute value less than %s", precision, scale, lt)
	}
	return nil
}