# question about long\_query\_time **URL:** \ **Category:** Other MySQL® Questions\ **Created:** [December 17, 2009, 4:59am UTC](https://forums.percona.com/t/question-about-long-query-time/1310 "2009-12-17T04:59:33Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![dizhenxiong](https://avatars.discourse-cdn.com/v4/letter/d/bb73d2/32.png) [@dizhenxiong](https://forums.percona.com/u/dizhenxiong)\ **Post date:** [December 17, 2009, 4:59am UTC](https://forums.percona.com/t/question-about-long-query-time/1310/1 "2009-12-17T04:59:33Z")
I have set my db serser’s long\_query\_time to 0,but it seems it doesn’t seem work! mysql\> show global variables like ‘%long%’; ±----------------±---------+ | Variable\_name | Value | ±----------------±---------+ | long\_query\_time | 0.000000 | ±----------------±---------+ 1 row in set (0.00 sec) The initial value is 5s,but after change to 0,it log some queries,but not all! Can anybody tell me why？ ---
**Author:** ![xaprb](https://avatars.discourse-cdn.com/v4/letter/x/49beb7/32.png) [@xaprb](https://forums.percona.com/u/xaprb)\ **Post date:** [December 18, 2009, 11:23am UTC](https://forums.percona.com/t/question-about-long-query-time/1310/2 "2009-12-18T11:23:17Z")
There are old sessions that remain open and have not yet been affected by the change to the global variable. Percona’s patches have a method to force this to take effect: [http://www.percona.com/docs/wiki/patches:use\_global\_long\_que](http://www.percona.com/docs/wiki/patches:use_global_long_que) ry\_time ---
**Author:** ![dizhenxiong](https://avatars.discourse-cdn.com/v4/letter/d/bb73d2/32.png) [@dizhenxiong](https://forums.percona.com/u/dizhenxiong)\ **Post date:** [December 20, 2009, 5:58am UTC](https://forums.percona.com/t/question-about-long-query-time/1310/3 "2009-12-20T05:58:40Z")
:o Thank you very much