Bug #105614 items with “sending data” and never finish

• Submitted: 17 Nov 2021 13:23
• Modified: 17 Nov 2021 14:15
• Reporter: alex wu
• Status: Unsupported
• Category: MySQL Server
• Severity: S2 (Serious)
• Version: mysql 5.6
• OS: CentOS
• CPU Architecture: x86

[17 Nov 2021 13:23] alex wu

Description:
It is happened  When the client is disconnected abnormally。 
normal,it will finish in a few minutes.
we can not repeat it so far.

SQL :
select count(1) from (
select `crm_sik`.`sik`,`crm_sik`.`dsk_num`,`crm_sik`.`pop_user_id`,`crm_sik`.`customer_name`,`crm_sik`.`user_id`,`crm_sik`.`customer_user_id`,`crm_sik`.`real_name`,`crm_sik`.`commodity_series`,count(`dsk`.`state`) from 
`crm_sik` 
left join (
select * from q1.`t1` union all 
select * from q1.`t2` union all
select * from q1.`t3` union all
select * from q1.`t4` union all
select * from q1.`t5` union all
select * from q1.`t6` union all
select * from q1.`t7` union all
select * from q1.`t8` union all
select * from q1.`t9` ) `dsk`
on `crm_sik`.`sik` = `dsk`.`belong` 
group by `crm_sik`.`sik`
);

------------------
we catch the processlist:
Query","75294","Sending data","select count(1) from ( select `crm_sik`.`sik`,`crm_sik`.`dsk_num`,`crm_sik`.`pop_user_id`,`crm_sik`."

execution time is so long and it don't finish.

How to repeat:
It is happened  When the client is disconnected abnormally。 

but we can't repeat it.

[17 Nov 2021 14:15] MySQL Verification Team

Hi Mr. wu,

Thank you for your bug report.

However, we can accept only those reports that contain a fully repeatable test case. Your report is not of that kind.

Regarding client being aborted, that has to be repeatable  by us. It is quite possible that you did not use quick option on the client-side and with many of those UNION ALL, you might have simply run out of memory.

Can't repeat.

More important than that fact is the fact that we do not support version 5.6 any more ......