Pošto ne mogu da prikažem čitav kod i upit, evo samo taj dio zbog kojeg se javlja filesort i ekipa. Da li neko može iz ovoga da mi kratko objasni zašto MySQL ne koristi indekse.
select sql_no_cache article_metadata.id from article_metadata inner JOIN city ON article_metadata.city_id = city.id where `city_name` = 'beograd' group by article_metadata.id
| Field | Type | Null | Key | Default | Extra |
+-----------+----------------------+------+-----+---------+----------------+
| id | smallint(5) unsigned | NO | PRI | NULL | auto_increment |
| city_name | varchar(45) | NO | | NULL | |
+-----------+----------------------+------+-----+---------+----------------+
+------------------------+----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------------------+----------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| city_id | smallint(5) unsigned | NO | MUL | NULL | |
+------------------------+----------------------+------+-----+---------+----------------+