tidb_decode_key解析不了key?

没错,能解析出来的都是很长的key:

MySQL [information_schema]> select tidb_decode_key('748000000000001DFFB45F72CC00000002FF0A6CEA0000000000FA');
+---------------------------------------------------------------------------+
| tidb_decode_key('748000000000001DFFB45F72CC00000002FF0A6CEA0000000000FA') |
+---------------------------------------------------------------------------+
| {"_tidb_rowid":5476377146916760810,"table_id":"7604"}                     |
+---------------------------------------------------------------------------+
1 row in set (0.00 sec)

MySQL [information_schema]> select tidb_decode_key('7480000000000014FFC800000000000000F8');
+---------------------------------------------------------+
| tidb_decode_key('7480000000000014FFC800000000000000F8') |
+---------------------------------------------------------+
| 7480000000000014FFC800000000000000F8                    |
+---------------------------------------------------------+
1 row in set, 1 warning (0.00 sec)