错误代码：2013。查询30.002秒期间与MySQL服务器的连接断开

Question

There are a lot of issues with the same topic as mine but my content and issue seems to be different. In my workbench, i run the code

`select(msgid) from `table`.log where 
 id = 'example'  and  status = 'active'  and month(created_at) = 12 
 and year(created_at) = 2018 limit 0,10;`

The above code works fine but when i run the code b

`select(msgid), count(msgid) from `table`.log where 
     id = 'example'  and  status = 'active'  and month(created_at) = 12 
     and year(created_at) = 2018 limit 0,10;`

i get the error

> Error Code: 2013. Lost connection to MySQL server during query 30.002 sec

Why could this be happening in my workbench ?

PS: New to workbench and mysql

Answer 1

Here's a screenshot of the preferences from MySQL Workbench 8.0.13. I've put arrows indicating where you should select "SQL Editor" and then where you find the "DBMS connection read timeout interval" field.

I agree with the comment from @SalmanA, you should optimize your query so it's not so slow.

In particular, you should use indexes to help the query narrow down the rows to report. But you can't do that when you use functions like month(created_at) and year(created_at) . Presuming you have an index on created_at , you need to put that column by itself on the left side of comparison operators:

... AND created_at >= '2018-12-01' AND created_at < '2019-01-01'

The best index for this query would be a compound index:

ALTER TABLE log ADD INDEX (id, status, created_at, msg_id);

Answer 2

You should try to increase DBMS connection read time out .

Go to Workbench Edit → Preferences → SQL Editor → DBMS connections read time out : increase this to 6000

Answer 3

You can change timeout from :

Edit → Preferences → SQL Editor → DBMS connection read time out (in seconds): 600

Changed it to a greater value than your current.

**UPDATE you can set read timeout also by:

SET @@local.net_read_timeout=360;