mysql-使用问题记录-1

背景：

mysql所在服务器停服关机，忘记把从库mysql停掉，等主库启动从库报错：
Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'log event entry exceeded max_allowed_packet; Increase max_allowed_packet on master'

经排查得知两边max_allowed_packet值不一致，slave上的值和配置文件中的值不一致，修改一致后从库就好了，至于为啥不一致了 我也很惆怅

环境：

mysql Ver 14.14 Distrib 5.5.13, for Linux (x86_64) using readline 5.1
CentOS release 6.9 (Final)

操作：

两边统一设置32M/不重启设置方法

Master：

mysql> select @@global.max_allowed_packet/1024/1024 MB;
+-------------+
| MB |
+-------------+
| 16.00000000 |
+-------------+
1 row in set (0.00 sec)

mysql> set @@global.max_allowed_packet=32*1024*1024;
Query OK, 0 rows affected (0.00 sec)

mysql> select @@global.max_allowed_packet/1024/1024 MB;
+-------------+
| MB |
+-------------+
| 32.00000000 |
+-------------+
1 row in set (0.00 sec)

Slave：
mysql> set @@global.max_allowed_packet=32*1024*1024;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> select @@global.max_allowed_packet/1024/1024 MB;
+-------------+
| MB |
+-------------+
| 32.00000000 |
+-------------+
1 row in set (0.00 sec)

查看salve状态 恢复正常

注：

max_allowed_packet的作用
参考 https://baike.baidu.com/item/max-allowed-packet/2685407?fr=aladdin