Simple but slow way to decode PostgreSQL timestamptz

codec.go

func decodeTimestamptzISO(s []byte) time.Time {
  if s[4] != '-' {
    // Replace year with a 4-digit year that can be parsed
    yearSep := bytes.IndexByte(s, '-')
    year, _ := strconv.Atoi(string(s[:yearSep]))
    replaced := append([]byte(`9600`), s[yearSep:]...)

    // Add back remaining years
    return decodeTimestamptzISO(replaced).AddDate(year-9600, 0, 0)
  }

  if s[len(s)-1] == 'C' {
    // Time is before current era
    yearSep := bytes.IndexByte(s, '-')
    year, _ := strconv.Atoi(string(s[:yearSep]))
    replaced := append([]byte(`0001`), s[yearSep:len(s)-3]...)

    return decodeTimestamptzISO(replaced).AddDate(-year, 0, 0)
  }

  const (
    HourOffset   = "2006-01-02 15:04:05.999999999-07"
    MinuteOffset = "2006-01-02 15:04:05.999999999-07:00"
    SecondOffset = "2006-01-02 15:04:05.999999999-07:00:00"
  )

  var result time.Time
  var err error

  switch {
  case s[len(s)-3] != ':':
    result, err = time.ParseInLocation(HourOffset, string(s), locZeroOffset)
  case s[len(s)-6] != ':':
    result, err = time.ParseInLocation(MinuteOffset, string(s), locZeroOffset)
  default:
    result, err = time.ParseInLocation(SecondOffset, string(s), locZeroOffset)
  }

  if err != nil {
    errorf(err.Error())
  }
  return result
}