# Cannot start logging of slow queries at run-time

**URL:** <https://forums.percona.com/t/cannot-start-logging-of-slow-queries-at-run-time/5337>\
**Category:** Percona Server for MySQL 5.6\
**Created:** [January 11, 2017, 5:16am UTC](https://forums.percona.com/t/cannot-start-logging-of-slow-queries-at-run-time/5337 "2017-01-11T05:16:27Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![mskidan](https://avatars.discourse-cdn.com/v4/letter/m/97f17d/32.png) [@mskidan](https://forums.percona.com/u/mskidan)\
**Post date:** [January 11, 2017, 5:16am UTC](https://forums.percona.com/t/cannot-start-logging-of-slow-queries-at-run-time/5337/1 "2017-01-11T05:16:27Z")

</div>

Hi!  
I cannot configure my Percona-mysql instance to start logging of slow queries:

Server version: 5.6.21-70.1-56-log Percona XtraDB Cluster (GPL), Release rel70.1, Revision 938, WSREP version 25.8, wsrep\_25.8.r4150

It is resetting “slow\_query\_log” every moment.

Checking the “slow\_query\_log” . It is OFF now:

mysql\> show global variables like ‘slow\_query\_log’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log  
 Value: OFF  
1 row in set (0.00 sec)

Switching it ON:

mysql\> set global slow\_query\_log=1;  
Query OK, 0 rows affected (0.00 sec)

Checking the “slow\_query\_log” . It is ON now:

mysql\> show global variables like ‘slow\_query\_log’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log  
 Value: ON  
1 row in set (0.00 sec)

Checking one more time the “slow\_query\_log” in a few moments . It is OFF now:

mysql\> show global variables like ‘slow\_query\_log’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log  
 Value: OFF  
1 row in set (0.00 sec)

Checking the slow log file size:

[root@sugardb1 mysql]# ll /data/mysql/sugardb1-slow.log  
-rw-r–r-- 1 mysql root 0 Jan 11 12:23 /data/mysql/sugardb1-slow.log  
[root@sugardb1 mysql]# ll /data/mysql/sugardb1-slow.log  
-rw-r–r-- 1 mysql root 260 Jan 11 12:23 /data/mysql/sugardb1-slow.log  
[root@sugardb1 mysql]# ll /data/mysql/sugardb1-slow.log  
-rw-r–r-- 1 mysql root 0 Jan 11 12:23 /data/mysql/sugardb1-slow.log  
[root@sugardb1 mysql]# ll /data/mysql/sugardb1-slow.log  
-rw-r–r-- 1 mysql root 0 Jan 11 12:24 /data/mysql/sugardb1-slow.log  
[root@sugardb1 mysql]# ll /data/mysql/sugardb1-slow.log  
-rw-r–r-- 1 mysql root 260 Jan 11 12:24 /data/mysql/sugardb1-slow.log

The file has been resetting.

The system variables are

mysql\> show global variables like ‘log\_slow%’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_admin\_statements  
Value: ON  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 2. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_filter  
Value:  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 3. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_rate\_limit  
Value: 10  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 4. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_rate\_type  
Value: query  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 5. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_slave\_statements  
Value: ON  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 6. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_sp\_statements  
Value: ON  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 7. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: log\_slow\_verbosity  
Value: microtime,query\_plan,innodb  
7 rows in set (0.00 sec)

[I]mysql\> show global variables like ‘slow\_query%’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log  
Value: OFF  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 2. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log\_always\_write\_time  
Value: 0.010000  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 3. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log\_file  
Value: /data/mysql/sugardb1-slow.log  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 4. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log\_timestamp\_always  
Value: ON  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 5. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log\_timestamp\_precision  
Value: microsecond  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 6. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: slow\_query\_log\_use\_global\_control  
Value: log\_slow\_filter,log\_slow\_rate\_limit,log\_slow\_verbosity,long\_query\_time,min\_examined\_row\_limit  
6 rows in set (0.00 sec)

mysql\> [/I]

[I]mysql\> show variables like ‘performance\_schema’ \G  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* 1. row \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Variable\_name: performance\_schema  
Value: OFF  
1 row in set (0.00 sec)

Can someone give me advice howto resolve this issue?[/I]

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<div class="post-metadata">

**Author:** ![mskidan](https://avatars.discourse-cdn.com/v4/letter/m/97f17d/32.png) [@mskidan](https://forums.percona.com/u/mskidan)\
**Post date:** [January 13, 2017, 9:57am UTC](https://forums.percona.com/t/cannot-start-logging-of-slow-queries-at-run-time/5337/2 "2017-01-13T09:57:48Z")

</div>

Also strange flapping of the system variable:

[I]mysql\> SHOW variables like ‘slow\_query\_log’;  
±---------------±------+  
| Variable\_name | Value |  
±---------------±------+  
| slow\_query\_log | ON |  
±---------------±------+  
1 row in set (0.00 sec)

mysql\> SHOW variables like ‘slow\_query\_log’;  
±---------------±------+  
| Variable\_name | Value |  
±---------------±------+  
| slow\_query\_log | OFF |  
±---------------±------+  
1 row in set (0.00 sec)

mysql\> SHOW variables like ‘slow\_query\_log’;  
±---------------±------+  
| Variable\_name | Value |  
±---------------±------+  
| slow\_query\_log | ON |  
±---------------±------+  
1 row in set (0.00 sec)

mysql\> SHOW variables like ‘slow\_query\_log’;  
±---------------±------+  
| Variable\_name | Value |  
±---------------±------+  
| slow\_query\_log | OFF |  
±---------------±------+  
1 row in set (0.00 sec)[/I]

Server version is

Server version: 5.6.21-70.1-56-log Percona XtraDB Cluster (GPL), Release rel70.1, Revision 938, WSREP version 25.8, wsrep\_25.8.r4150