已知该sql关联的表数据量很大，
sql语句: insert into a select ... from b left jon c ... left join d ...
1.设置了 {"useSSL":"false","socketTimeout":"5600034"}。
2.SET query_timeout = 5000;
报错提示：
execute sql error: Communications link failure
The last packet successfully received from the server was 3,600,017 milliseconds ago
疑问点：既然提示3,600,017ms,那么应该是某个参数超时造成的，需要调整哪个或者哪些参数避免执行异常呢？
