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18 lines
1.2 KiB
SQL
18 lines
1.2 KiB
SQL
explain
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select actor_id from (
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select actor_id from sakila.actor
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) as der_1
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union
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select film_id from (
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select film_id from sakila.film
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) as der_2;
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+----+--------------+------------+-------+---------------+--------------------+---------+------+------+-------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
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+----+--------------+------------+-------+---------------+--------------------+---------+------+------+-------------+
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| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 200 | |
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| 2 | DERIVED | actor | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
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| 3 | UNION | <derived4> | ALL | NULL | NULL | NULL | NULL | 1000 | |
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| 4 | DERIVED | film | index | NULL | idx_fk_language_id | 1 | NULL | 951 | Using index |
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| NULL | UNION RESULT | <union1,3> | ALL | NULL | NULL | NULL | NULL | NULL | |
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+----+--------------+------------+-------+---------------+--------------------+---------+------+------+-------------+
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