mysql5中大数据错误：Packet for query is too large (1117260 > 1048576). You can change this value on the ser

mysql5数据，插入或更新字段有大数据时（大于1M），会出现如下错误：

SEVERE: Servlet.service() for servlet [webs] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.TransientDataAccessResourceException: Hibernate flushing: Could not
execute JDBC batch update; SQL [update t_article set (省略部分...)author_id=? where id=?];
Packet for query is too large (1117260 > 1048576). You can change this value on the server by setting the max_allowed_packet' variable.; nested exception is java.sql.BatchUpdateException: Packet for query
is too large (1117260 > 1048576). You can change this value on the server by setting the max_allowed_packet' variable.] with root cause java.sql.BatchUpdateException: Packet for query is too large (1117260 > 1048576). You can change this value on the server
by setting the max_allowed_packet' variable.

开始以为是相应字段的类型设置不正确，超出了字段的最大范围，网上查询后发现是mysql默认加载的数据文件不超过1M，可以通过更改mysql的配置文件my.cnf（Linux，或windows的my.ini）来更改这一默认值，从而达到插入大数据的目的。

解决：
MySQL的一个系统参数：max_allowed_packet，其默认值为1048576(1M)，
可以先查询一下：show VARIABLES like '%max_allowed_packet%';
修改此变量的值：MySQL安装目录下的my.ini文件中的[mysqld]段中的＂max_allowed_packet = 1M＂，如更改为4M(如果没有这行内容，增加一行)，保存，重新启动MySQL服务。现在可以load大于1M的文件了。

有时候命令“SET GLOBAL max_allowed_packet=16*1024*1024”无效，需要使用如下命令：set @@max_allowed_packet=5*1024*1024