mysql：Cause: com.mysql.cj.jdbc.exceptions.PacketTooBigException: Packet for query is too large

### Cause: com.mysql.cj.jdbc.exceptions.PacketTooBigException: Packet for query is too large (4,246,837 > 4,194,304). You can change this value on the server by setting the 'max_allowed_packet' variable.
; Packet for query is too large (4,246,837 > 4,194,304). You can change this value on the server by setting the 'max_allowed_packet' variable.; nested exception is com.mysql.cj.jdbc.exceptions.PacketTooBigException: Packet for query is too large (4,246,837 > 4,194,304). You can change this value on the server by setting the 'max_allowed_packet' variable., path=/user/addList}]

 

查看 max_allowed_packet 参数：

show VARIABLES like '%max_allowed_packet%';

结果：

修改方法：

1、修改配置文件。编辑my.cnf来修改（windows下my.ini）

max_allowed_packet = 20M

2、在mysql命令行中暂时修改，重新启动MYSQL后，会恢复原来的值。

//这里的数值为字节数，这里改为20M，需要重新登陆客户端起作用
set global max_allowed_packet = 2*1024*1024*10