mysql> create database dede;
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47299
current database: none
query ok, 1 row affected (0.00 sec)
mysql> grant all privileges on dede.* to 『dede『@『localhost『 identified by 『dede123『; ##授權時執行失敗
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47302
current database: none
error 1044 (42000): access denied for user 『root『@『%『 to database 『dede『 ##拒絕訪問的使用者
解決：mysql> select grant_priv from mysql.user where host=『localhost『; ##n代表沒有許可權
| grant_priv |
| n |
| n |
| n |
3 rows in set (0.00 sec)
mysql> select grant_priv from mysql.user where host=『127.0.0.1『;
| grant_priv |
| y |
1 row in set (0.00 sec)
mysql> update mysql.user set grant_priv=『y『 where host=『localhost『;
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47312
current database: none
query ok, 3 rows affected (0.01 sec)
rows matched: 3 changed: 3 warnings: 0
mysql> select grant_priv from mysql.user where host=『localhost『;
| grant_priv |
| y |
| y |
| y |
3 rows in set (0.00 sec)
mysql> flush privileges;
query ok, 0 rows affected (0.00 sec)
mysql> grant all privileges on dede.* to 『dede『@『localhost『 identified by 『dede123『;
error 1044 (42000): access denied for user 『root『@『%『 to database 『dede『
mysql> show variables like 『read_only『
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47323
current database: none
| variable_name | value |
| read_only | off |
1 row in set (0.00 sec)
mysql> show global variables like 『max_allowed_packet『; ##檢視max_allowed_packet的值，預設是1mb
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47339
current database: none
| variable_name | value |
| max_allowed_packet | 1048576 |
1 row in set (0.00 sec)
mysql> set global max_allowed_packet=1024102416; ##臨時修改max_allowed_packet值為16mb，重啟失效
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47341
current database: none
query ok, 0 rows affected (0.00 sec)
mysql> show global variables like 『max_allowed_packet『; ##檢視.,臨時已生效
| variable_name | value |
| max_allowed_packet | 16777216 |
1 row in set (0.00 sec)
mysql> grant all privileges on dede.* to 『dede『@『localhost『 identified by 『dede123『; ###grant授權使用者成功
error 2006 (hy000): mysql server has gone away
no connection. trying to reconnect...
connection id: 47347
current database: none
query ok, 0 rows affected (0.00 sec)
mysql> exit
bye###永久修改引數
[[email protected] ~]# vim /etc/my.cnf
[mysqld]
max_allowed_packet = 16m
mysql 重啟生效
原文：
mysql 故障案例 mysql故障案例
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