MySQL5.7新特性之explain UPDATE/DELETE/INSERT
在MySQL5.5版本中，explain查看执行计划，只能支持select语句，但是在MySQL5.6/5.7版本中，可以支持DML语句，即UPDATE、DELETE、INSERT。
建立测试表accessLog和accessLog_bak进行测试：
建立测试表accessLog和accessLog_bak进行测试：
点击(此处)折叠或打开
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mysql> explain select * from accessLog where id=16649850;
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
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| 1 | SIMPLE | accessLog | NULL | const | PRIMARY | PRIMARY | 8 | const | 1 | 100.00 | NULL |
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
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1 row in set, 1 warning (0.00 sec)
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mysql> explain delete from accessLog where id=16649850;
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
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| 1 | DELETE | accessLog | NULL | range | PRIMARY | PRIMARY | 8 | const | 1 | 100.00 | Using where |
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+----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
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1 row in set (0.00 sec)
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mysql> explain update accessLog_bak set id=111 where id=16649867;
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
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| 1 | UPDATE | accessLog_bak | NULL | ALL | NULL | NULL | NULL | NULL | 582486 | 100.00 | Using where |
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
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1 row in set (0.02 sec)
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mysql> explain insert into accessLog select * from accessLog_bak where id=111;
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
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| 1 | INSERT | accessLog | NULL | ALL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
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| 1 | SIMPLE | accessLog_bak | NULL | ALL | NULL | NULL | NULL | NULL | 582486 | 10.00 | Using where |
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+----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
- 2 rows in set (0.02 sec)
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/30135314/viewspace-2144572/ ，如需转载，请注明出处，否则将追究法律责任。
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