Mysql数据库InnoDB表和MyISAM表混用后，事务回滚测试。

Posted 2020-11-14 Colinshi

测试环境CENTOS7.3+mysql5.7

一张表使用InnoDB引擎，表名称 innodb_test

另外一张表使用MyISAM引擎，表名称 innodb_test

在事务操作的时候，看看到底会发生什么情况。

表结构相同只有3个字段id，name, money
+-------+---------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------+------+-----+---------+----------------+
| id | int(10) | NO | PRI | NULL | auto_increment |
| name | char(30) | YES | | NULL | |
| money | decimal(11,2) | YES | | NULL | |
+-------+---------------+------+-----+---------+----------------+

两张表都只有一条数据

+----+----------+---------+
| id | name | money |
+----+----------+---------+
| 1 | colinshi | 1000.00 |
+----+----------+---------+

先关闭了自动事务提交

mysql> SET AUTOCOMMIT =0;

Query OK, 0 rows affected (0.00 sec)

mysql> show variables like ‘autocommit‘ ;

+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| autocommit | OFF |
+---------------+-------+
mysql> begin;

开始事务操作，这次测试成功commit

mysql> update innodb_test set money=500 WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

mysql> update myisam_test set money=500 WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from innodb_test;
+----+----------+--------+
| id | name | money |
+----+----------+--------+
| 1 | colinshi | 500.00 |
+----+----------+--------+
1 row in set (0.00 sec)

mysql> select * from myisam_test;
+----+----------+--------+
| id | name | money |
+----+----------+--------+
| 1 | colinshi | 500.00 |
+----+----------+--------+
1 row in set (0.00 sec)

在成功commit的情况下数据库没有问题。都成了500，那么如果提交错误需要回滚会是什么情况呢。

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> update myisam_test set money=300 WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

mysql> update innodb_test set money=300 WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

mysql> rollback;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select * from myisam_test;
+----+----------+--------+
| id | name | money |
+----+----------+--------+
| 1 | colinshi | 300.00 |
+----+----------+--------+
1 row in set (0.00 sec)

mysql> select * from innodb_test;
+----+----------+--------+
| id | name | money |
+----+----------+--------+
| 1 | colinshi | 500.00 |
+----+----------+--------+
1 row in set (0.00 sec)

发现MyISAM表并没有进行回滚操作，而InnoDB表进行了回滚操作。

也就是说一个事务如果同时处理了MyISAM引擎表，InnoDB引擎表，那么回滚会出现数据不一致的情况。

我还直接使用了python的mysql对数据库使用了事务操作结果和mysql客户端是相同情况

import pymysql
import time

def delSql(dzp_id):
    conn = pymysql.connect(host=‘192.168.1.71‘, user=‘root‘, passwd=‘!QAZ2wsx‘, db=‘colinshitop‘)
    cur = conn.cursor()
    cur.execute(‘use colinshitop‘)
    try:
        cur.execute("update innodb_test set money=‘{}‘  WHERE id = 1".format(dzp_id))
        cur.execute("update myisam_test set money=‘{}‘  WHERE id = 1".format(dzp_id))
        cur.execute("INSERT into name (‘name‘, ‘fdjaskfjsa‘) VALUES (‘fdkjakf‘, ‘值2‘)")
        conn.commit()
        print(‘提交commit‘)
    except:
        conn.rollback()
        print(‘回滚rollback‘)
    finally:
        cur.close()
        conn.close()

if __name__ == ‘__main__‘:
    dzp_id = input(‘请输入金额：‘,)
    delSql(dzp_id)
    print(‘5秒后程序终止‘)
    time.sleep(5)

 

数据库中尽量不要同时用InnoDB表和MyISAM表混用。如果真的迫不得已需要混用，一定不能同一个事务同时对两种表引擎操作。