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：

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 mysql> explain select * from accessLog where id=16649850;
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
 | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
 | 1 | SIMPLE | accessLog | NULL | const | PRIMARY | PRIMARY | 8 | const | 1 | 100.00 | NULL |
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
 1 row in set, 1 warning (0.00 sec)

 mysql> explain delete from accessLog where id=16649850;
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
 | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
 | 1 | DELETE | accessLog | NULL | range | PRIMARY | PRIMARY | 8 | const | 1 | 100.00 | Using where |
 +----+-------------+-----------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
 1 row in set (0.00 sec)

 mysql> explain update accessLog_bak set id=111 where id=16649867;
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 | 1 | UPDATE | accessLog_bak | NULL | ALL | NULL | NULL | NULL | NULL | 582486 | 100.00 | Using where |
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 1 row in set (0.02 sec)

 mysql> explain insert into accessLog select * from accessLog_bak where id=111;
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 | 1 | INSERT | accessLog | NULL | ALL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
 | 1 | SIMPLE | accessLog_bak | NULL | ALL | NULL | NULL | NULL | NULL | 582486 | 10.00 | Using where |
 +----+-------------+---------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
 2 rows in set (0.02 sec)

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