mysql-JDBC通过SSHTunnel连接MySQL数据库

JDBC 通过SSH Tunnel连接MySQL数据库，在获取connection 的时候总是报查询信息太多，是怎么回事？
具体信息如下：Exception in thread "main" com.mysql.jdbc.PacketTooBigException: Packet for query is too large (4739923 > 1048576). You can change this value on the server by setting the max_allowed_packet' variable.