code: func IsTooBigFieldLength(colDefTpFlen int, colDefName, setCharset string) error {
  	desc, err := charset.GetCharsetDesc(setCharset)
  	if err != nil {
  		return errors.Trace(err)
  	}
  	maxFlen := mysql.MaxFieldVarCharLength
  	maxFlen /= desc.Maxlen
  	if colDefTpFlen != types.UnspecifiedLength && colDefTpFlen > maxFlen {
  		return types.ErrTooBigFieldLength.GenWithStack("Column length too big for column '%s' (max = %d); use BLOB or TEXT instead", colDefName, maxFlen)
  	}
  	return nil
  }
docs: // IsTooBigFieldLength check if the varchar type column exceeds the maximum length limit.