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

11 lines
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SQL

mysql> explain select film.film_id from sakila.film left join sakila.film_actor using(film_id) where film_actor.film_id is null;
+----+-------------+------------+-------+----------------+--------------------+---------+---------------------+------+--------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+-------+----------------+--------------------+---------+---------------------+------+--------------------------------------+
| 1 | SIMPLE | film | index | NULL | idx_fk_language_id | 1 | NULL | 951 | Using index |
| 1 | SIMPLE | film_actor | ref | idx_fk_film_id | idx_fk_film_id | 2 | sakila.film.film_id | 2 | Using where; Using index; Not exists |
+----+-------------+------------+-------+----------------+--------------------+---------+---------------------+------+--------------------------------------+
2 rows in set (0.00 sec)
mysql> notee