# Temporary Tables on virtual memory

**URL:** <https://forums.percona.com/t/temporary-tables-on-virtual-memory/323>\
**Category:** Other MySQL® Questions\
**Created:** [May 16, 2007, 2:09am UTC](https://forums.percona.com/t/temporary-tables-on-virtual-memory/323 "2007-05-16T02:09:44Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![philb](https://avatars.discourse-cdn.com/v4/letter/p/ea666f/32.png) [@philb](https://forums.percona.com/u/philb)\
**Post date:** [May 16, 2007, 2:09am UTC](https://forums.percona.com/t/temporary-tables-on-virtual-memory/323/1 "2007-05-16T02:09:44Z")

</div>

Hello everyone,

I’m running a configuration with one master and a replication slave. Both on Linux.

For better performance, I decided some days ago to put the tmpdir to /dev/shm like a recommandation I read. And the performance increases a lot. Because I’ve a lot of created\_tmp\_disk\_tables created (about 751K on a total of 3743K of created\_tmp\_tables. Because on my SELECTs, I must get text fields).

But today, I read this :  
[URL][http://dev.mysql.com/doc/refman/5.0/en/temporary-files.html[/URL]](http://dev.mysql.com/doc/refman/5.0/en/temporary-files.html%5B/URL%5D) where it was specified to don’t put the tmpdir to virtual memory on a slave.

So my question is : In which case, it is dangerous to put the tmdir in virtual memory for a slave ?  
Do you have a workaround to continue to put only created\_tmp\_disk\_tables on virtual memory and not the temporary tables necessary for the replication ?

Thanks for yours answers.

Best regards.