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percona-toolkit/t/pt-visual-explain/samples/dependent_subquery.sql
2011-06-24 16:02:05 -06:00

11 lines
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SQL

mysql> explain select actor_id, (select count(*) from sakila.film_actor where film_actor.actor_id = actor.actor_id) from sakila.actor;
+----+--------------------+------------+-------+---------------+---------+---------+----------------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+------------+-------+---------------+---------+---------+----------------+------+--------------------------+
| 1 | PRIMARY | actor | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
| 2 | DEPENDENT SUBQUERY | film_actor | ref | PRIMARY | PRIMARY | 2 | actor.actor_id | 13 | Using where; Using index |
+----+--------------------+------------+-------+---------------+---------+---------+----------------+------+--------------------------+
2 rows in set (0.00 sec)
mysql> notee