混乱中
mysql> explain select * from test order by value\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: test type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 10000365 Extra: Using filesort 1 row in set (0.00 sec) mysql> explain select * from test order by value limit 1\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: test type: index possible_keys: NULL key: value key_len: 386 ref: NULL rows: 1 Extra: 1 row in set (0.00 sec)