Changing the tmp folder of mysql - mysql

Question

Our Mysql queries use temporary tables which creates temporary files in the process. Currently the files are written to /tmp. How exactly can the path of the temp folder to which mysql writes to be changed?

Answer 1

You should edit your my.cnf
tmpdir = /whatewer/you/want
and after that restart mysql
P.S. Don't forget give write permissions to /whatewer/you/want for mysql user

Answer 2

Here is an example to move the mysqld tmpdir from /tmp to /run/mysqld which already exists on Ubuntu 13.04 and is a tmpfs (memory/ram):
sudo vim /etc/mysql/conf.d/local.cnf
Add:
[mysqld]
tmpdir = /run/mysqld
Then:
sudo service mysql restart
Verify:
SHOW VARIABLES LIKE 'tmpdir';
==================================================================
If you get an error on MySQL restart, you may have AppArmor enabled:
sudo vim /etc/apparmor.d/local/usr.sbin.mysqld
Add:
# Site-specific additions and overrides for usr.sbin.mysqld.
# For more details, please see /etc/apparmor.d/local/README.
/run/mysqld/ r,
/run/mysqld/** rwk,
Then:
sudo service apparmor reload
sources: http://2bits.com/articles/reduce-your-servers-resource-usage-moving-mysql-temporary-directory-ram-disk.html, https://blogs.oracle.com/jsmyth/entry/apparmor_and_mysql

Answer 3

This is answered in the documentation:
Where MySQL Stores Temporary Files
On Unix, MySQL uses the value of the TMPDIR environment variable as
the path name of the directory in which to store temporary files. If
TMPDIR is not set, MySQL uses the system default, which is usually
/tmp, /var/tmp, or /usr/tmp.
On Windows, Netware and OS2, MySQL checks in order the values of the
TMPDIR, TEMP, and TMP environment variables. For the first one found
to be set, MySQL uses it and does not check those remaining. If none
of TMPDIR, TEMP, or TMP are set, MySQL uses the Windows system
default, which is usually C:\windows\temp.

Answer 4

if you dont have apparmor or selinux issues, but still get errorcode 13's:
mysql must be able to access the full path. I.e. all folders must be mysql accessible, not just the one you intend in pointing to.
example, you try using this in your mysql configuration: tmp = /some/folder/on/disk
# will work, as user root:
mkdir -p /some/folder/on/disk
chown -R mysql:mysql /some
# will not work, also as user root:
mkdir -p /some/folder/on/disk
chown -R mysql:mysql /some/folder/on/disk

Answer 5

This maybe helpful for MySql with AppArmor
stop mysql :
sudo /etc/init.d/mysql stop
Create directory called /somewhere/tmp
Edit Config:
sudo vim /etc/mysql/my.cnf # or perhaps sudo vim /etc/mysql/mysql.conf.d/mysqld.cnf
change
tmpdir = /somewhere/tmp/
Then
sudo vim /etc/apparmor.d/usr.sbin.mysqld
Add
# Allow data dir access
/somewhere/ r,
/somewhere/** rwk,
sudo chown -R root:root /somewhere
sudo chmod -R 1777 /somewhere
Restart
sudo /etc/init.d/apparmor reload
sudo /etc/init.d/mysql restart

Answer 6

You can also set the TMPDIR environment variable.
In some situations (Docker in my case) it's more convenient to set an environment variable than to update a config file.

Answer 7

Works for 5.7 on centos 8
mkdir /tmp/1 /tmp/1
semanage fcontext -a -t mysqld_db_t "/tmp/1(/.*)?"
restorecon -Rv /tmp/1
semanage fcontext -a -t mysqld_db_t "/tmp/2(/.*)?"
restorecon -Rv /tmp/2
to my.cnf tmpdir=/tmp/1:/tmp/2
sudo service mysql restart

Answer 8

If you are a MariaDB user, all this above apply, by don't forget to unlock the "home" protection by doing this.
touch /etc/systemd/system/mariadb.service.d/override.conf
nano /etc/systemd/system/mariadb.service.d/override.conf
Inside override.conf put this content and save.
[Service]
ProtectHome=false
Then run the following commands :
systemctl daemon-reload
/scripts/restartsrv_mysql
After restarting mysql, the variables can be checked by :
mysqladmin variables|grep tmp