mysql报错Packet for query is too large (12238 > 1024). You can change this value

  今天将项目部署到linux服务器的时候莫名其妙的报一些错误,可是在本地啥错没有,通过实时查看tomcat 的日志之后发现报错是:  

实时查看日志:

1、先切换到:cd usr/local/tomcat5/logs

2、tail -f catalina.out

3、这样运行时就可以实时查看运行日志了

发现错误:

rg.springframework.dao.TransientDataAccessResourceException:
### Error querying database. Cause: com.mysql.jdbc.PacketTooBigException: Packet for query is too large (1233 > 1024). You can change this value on the server by setting the max_allowed_packet' variable.
### The error may exist in cn/xm/exam/mapper/employee/out/custom/UnitCustomMapper.xml
### The error may involve cn.xm.exam.mapper.employee.out.custom.UnitCustomMapper.getHaulunitByCondition-Inline
### The error occurred while setting parameters
### SQL: SELECT haulunit.unitId, haulunit.unitBigId, haulunit.bigId, (select group_concat(projectname) from project where projectid in (select projectId from haulunitproject where bigId =haulunit.bigId and unitId= haulunit.unitId)) as projectNames, haulunit.manager, haulunit.managerPhone, haulunit.secure, haulunit.securePhone, @b:= (IFNULL((SELECT SUM(minusNum) FROM breakrules, haulemployeeout WHERE breakrules.BigEmployeeoutId = haulemployeeout.BigEmployeeoutId AND haulemployeeout.unitid = haulunit.unitId and breakTime LIKE CONCAT(Year(CurDate()),'%') ),0)) AS unitMinisMum, haulinfo.bigName, haulinfo.bigStatus, haulinfo.bigCreateDate, unit.name, unit.address, unit.contact, unit.phone, @a:= (SELECT COUNT(BigEmployeeoutId) FROM haulemployeeout WHERE haulemployeeout.bigId = haulunit.bigId AND haulemployeeout.unitId = haulunit.unitId and trainstatus='2') AS personNum, TRUNCATE(IFNULL(@b/@a,0),3) AS jiaquan FROM haulunit, haulinfo, unit WHERE haulunit.bigId=haulinfo.bigId AND haulunit.unitId=unit.unitId and haulunit.bigId = ? ORDER BY jiaquan desc limit ?,?
### Cause: com.mysql.jdbc.PacketTooBigException: Packet for query is too large (1233 > 1024). You can change this value on the server by setting the max_allowed_packet' variable.
; SQL []; Packet for query is too large (1233 > 1024). You can change this value on the server by setting the max_allowed_packet' variable.; nested exception is com.mysql.jdbc.PacketTooBigException: Packet for query is too large (1233 > 1024). You can change this value on the server by setting the max_allowed_packet' variable.
at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.doTranslate(SQLStateSQLExceptionTranslator.java:107)
at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80)
at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80)

-----------------解决办法:(通过查看mysql全局变量发现原因是mysql限制了最大更新大小)----------------------

mysql max_allowed_packet 设置过小导致记录写入失败

mysql根据配置文件会限制server接受的数据包大小。

有时候大的插入和更新会受max_allowed_packet 参数限制,导致写入或者更新失败。

查看目前配置

show VARIABLES like '%max_allowed_packet%';

显示的结果为:

+--------------------+---------+

| Variable_name      | Value   |

+--------------------+---------+

| max_allowed_packet | 1048576 |

+--------------------+---------+

以上说明目前的配置是:1M

修改方法

1、修改配置文件

可以编辑my.cnf来修改(windows下my.ini),在[mysqld]段或者mysql的server配置段进行修改。

max_allowed_packet = 20M

如果找不到my.cnf可以通过

mysql --help | grep my.cnf

去寻找my.cnf文件。

linux下该文件在/etc/下。

2、在mysql命令行中修改

在mysql 命令行中运行

set global max_allowed_packet = 2*1024*1024*10

然后退出命令行,重启mysql服务,再进入。

show VARIABLES like '%max_allowed_packet%';

查看下max_allowed_packet是否编辑成功

 
 注意:该值设置过小将导致单个记录超过限制后写入数据库失败,且后续记录写入也将失败。
 
 
三、如何重启Linux的mysql

1、使用 service 启动:service mysqld restart

2、使用 mysqld 脚本启动:/etc/inint.d/mysqld restart

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