Query without ORDER BY slower?

Question

I'm executing the following on my INNODB database

QUERY WITHOUT ORDER BY

SELECT  SQL_NO_CACHE second_designer
    FROM  itemrow FORCE INDEX(second_designer)
    WHERE  category like '%'
      and  type like '%'
      and  availability like '%'
    GROUP BY  second_designer

259 results in 0.0286 seconds.

QUERY WITH ORDER BY DESC

SELECT  SQL_NO_CACHE second_designer
    FROM  itemrow FORCE INDEX(second_designer)
    WHERE  category like '%'
      and  type like '%'
      and  availability like '%'
    GROUP BY  second_designer
    ORDER BY  second_designer DESC 

259 results in 0.0008 seconds.

INDEX

ADD INDEX `second_designer` (`second_designer ` , `availability`,
                             `category`, `type`) USING BTREE

EXPLAIN

id select_type table   type  possible_keys   key         key_len ref  rows Extra
1  SIMPLE      itemrow index second_designer second_designer 608 NULL 44521 Using where; Using index

Why is the query with order by clause so much faster than the one without?

Answer 1

The difference was caused by the 'hidden' LIMIT phpMyAdmin adds to all queries.

$cfg['MaxRows'] Listed in phpMyAdmin Docs

After setting a LIMIT explicitly the queries both perform the same (259 results in 0.0286 seconds).