er friendly when wanting
to scan output from the command line.

Parameters
-----------

picoseconds (TEXT):
  The raw picoseconds value to convert.

Returns
-----------

TEXT CHARSET UTF8MB4

Example
-----------

mysql> select format_time(342342342342345);
+------------------------------+
| format_time(342342342342345) |
+------------------------------+
| 00:05:42                     |
+------------------------------+
1 row in set (0.00 sec)

mysql> select format_time(342342342);
+------------------------+
| format_time(342342342) |
+------------------------+
| 342.34 us              |
+------------------------+
1 row in set (0.00 sec)

mysql> select format_time(34234);
+--------------------+
| format_time(34234) |
+--------------------+
| 34.23 ns           |
+--------------------+
1 row in set (0.00 sec)
'
    SQL SECURITY INVOKER
    DETERMINISTIC
    NO SQL
BEGIN
  IF picoseconds IS NULL THEN RETURN NULL;
  ELSEIF picoseconds >= 604800000000000000 THEN RETURN CONCAT(ROUND(picoseconds / 604800000000000000, 2), ' w');
  ELSEIF picoseconds >= 86400000000000000 THEN RETURN CONCAT(ROUND(picoseconds / 86400000000000000, 2), ' d');
  ELSEIF picoseconds >= 3600000000000000 THEN RETURN CONCAT(ROUND(picoseconds / 3600000000000000, 2), ' h');
  ELSEIF picoseconds >= 60000000000000 THEN RETURN CONCAT(ROUND(picoseconds / 60000000000000, 2), ' m');
  ELSEIF picoseconds >= 1000000000000 THEN RETURN CONCAT(ROUND(picoseconds / 1000000000000, 2), ' s');
  ELSEIF picoseconds >= 1000000000 THEN RETURN CONCAT(ROUND(picoseconds / 1000000000, 2), ' ms');
  ELSEIF picoseconds >= 1000000 THEN RETURN CONCAT(ROUND(picoseconds / 1000000, 2), ' us');
  ELSEIF picoseconds >= 1000 THEN RETURN CONCAT(ROUND(picoseconds / 1000, 2), ' ns');
  ELSE RETURN CONCAT(picoseconds, ' ps');
  END IF;
END