gistfile1.sql

mysql> explain     SELECT u.facebook_uid
    ->       FROM users u
    -> INNER JOIN schedules s ON s.user_id = u.id AND u.id <> 1
    -> INNER JOIN schedule_courses sc ON sc.schedule_id = s.id
    -> INNER JOIN sections se ON sc.section_id = se.id AND se.course_id = 426;
+----+-------------+-------+--------+---------------------------------------+---------------------------------------+---------+---------------------------------+------+--------------------------+
| id | select_type | table | type   | possible_keys                         | key                                   | key_len | ref                             | rows | Extra                    |
+----+-------------+-------+--------+---------------------------------------+---------------------------------------+---------+---------------------------------+------+--------------------------+
|  1 | SIMPLE      | u     | index  | PRIMARY                               | index_users_on_facebook_uid           | 258     | NULL                            |    2 | Using where; Using index | 
|  1 | SIMPLE      | s     | ref    | PRIMARY,schedules_user_id_index2      | schedules_user_id_index2              | 5       | scheduleman_lroch.u.id          |    2 | Using where; Using index | 
|  1 | SIMPLE      | sc    | ref    | index_schedule_courses_on_schedule_id | index_schedule_courses_on_schedule_id | 4       | scheduleman_lroch.s.id          |    1 |                          | 
|  1 | SIMPLE      | se    | eq_ref | PRIMARY,index_sections_on_course_id   | PRIMARY                               | 4       | scheduleman_lroch.sc.section_id |    1 | Using where              | 
+----+-------------+-------+--------+---------------------------------------+---------------------------------------+---------+---------------------------------+------+--------------------------+