MySQL slow query using filesort

Question

I have speed problems with a MySQL query. The tables definitions are as follows:

CREATE TABLE IF NOT EXISTS `student` (
  `student_id` int(11) unsigned NOT NULL          


        

Answer 1

Try index:

KEY student_sort(countup DESC ,updated_time DESC)

Then use STRAIGHT_JOIN and FORCE INDEX:

SELECT *
FROM student force index(student_sort) STRAIGHT_JOIN 
     college 
         ON student.student_college = college.college_id
WHERE college_location = 1
ORDER BY student.countup desc, 
         student.updated_time desc
LIMIT 15;