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9 lines
850 B
SQL
9 lines
850 B
SQL
mysql> explain select 1 from sakila.actor as actor_1 union select 2 from sakila.actor as actor_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 | actor_1 | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
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| 2 | UNION | actor_2 | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
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| | UNION RESULT | <union1,2> | ALL | NULL | NULL | NULL | NULL | NULL | |
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+----+--------------+------------+-------+---------------+---------+---------+------+------+-------------+
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