Bug #70173 please remove sort aborted errors from the error log
Submitted: 28 Aug 2013 7:58 Modified: 15 Nov 2013 18:08
Reporter: Shane Bester (Platinum Quality Contributor) Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Optimizer Severity:S4 (Feature request)
Version:5.7.3 OS:Any
Assigned to: CPU Architecture:Any

[28 Aug 2013 7:58] Shane Bester
Description:
On current 5.7.3 tree, the default for log_error_verbosity (aka log_warnings) is 2 which causes huge amount of spam when running randomized queries.

performance_schema can be used to track query errors. Also, this is good enough information that is fetch-able by the client:

mysql> select group_concat(distinct t1.a) a
    -> from t1 where  t1.a = (select a from t1)
    -> group by  b;
ERROR 1242 (21000): Subquery returns more than 1 row
mysql> show warnings;
+-------+------+------------------------------------------------+
| Level | Code | Message                                        |
+-------+------+------------------------------------------------+
| Error | 1242 | Subquery returns more than 1 row               |
| Error | 1028 | Sort aborted: Subquery returns more than 1 row |
+-------+------+------------------------------------------------+
2 rows in set (0.00 sec)

Error log does NOT need this, which can lead to a DoS type of problem:

2013-08-28T07:55:35.003767Z 3 [ERROR] mysqld.exe: Sort aborted: Subquery returns more than 1 row
2013-08-28T07:55:35.004267Z 3 [Note] Sort aborted, host: , user: , thread: 3, query: select group_concat(distinct t1.a) a
from t1 where  t1.a = (select a from t1)
group by  b

How to repeat:
drop table if exists `t1`;
create table `t1` (`a` int,`b` int) engine=myisam;
insert into `t1` values (2,4),(7,8);
select group_concat(distinct t1.a) a
from t1 where  t1.a = (select a from t1)
group by  b;
[8 Oct 2013 11:51] Arnaud Adant
Note that the default verbosity is 3, not 2

http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_log_error_verbo...
[15 Nov 2013 18:08] Paul DuBois
Noted in 5.7.4 changelog.

The server wrote an excessive number of "Sort aborted" messages to
the error log.