Function addFrac

pkg/sql/sem/tree/interval.go:630–656

addFrac increases the duration given as first argument by the unit given as second argument multiplied by the factor in the third argument. For computing fractions there are 30 days to a month and 24 hours to a day.

(d duration.Duration, unit duration.Duration, f float64)

// argument. For computing fractions there are 30 days to a month and
// 24 hours to a day.
func addFrac(d duration.Duration, unit duration.Duration, f float64) (duration.Duration, error) {
	if unit.Months > 0 {
		f = f * float64(unit.Months)
		d.Months += int64(f)
		switch unit.Months {
		case 1:
			f = math.Mod(f, 1) * 30
			d.Days += int64(f)
			f = math.Mod(f, 1) * 24
			d.SetNanos(d.Nanos() + int64(float64(time.Hour.Nanoseconds())*f))
		case 12:
			// Nothing to do: Postgres limits the precision of fractional years to
			// months. Do not continue to add precision to the interval.
			// See issue #55226 for more details on this.
		default:
			return duration.Duration{}, errors.AssertionFailedf("unhandled unit type %v", unit)
		}
	} else if unit.Days > 0 {
		f = f * float64(unit.Days)
		d.Days += int64(f)
		f = math.Mod(f, 1) * 24
		d.SetNanos(d.Nanos() + int64(float64(time.Hour.Nanoseconds())*f))
	} else {
		d.SetNanos(d.Nanos() + int64(float64(unit.Nanos())*f))
	}
	return d, nil
}

// floatToNanos converts a fractional number representing nanoseconds to the
// number of integer nanoseconds. For example: ".354874219" to "354874219"