mysql select query "No Space Left On Device" - mysql

Question

My system is using Ubuntu with mysql database:
I have a complex mysql select query to run.
mysql -u root -p myDB < query.sql
But when I try to run it it always gives me:
ERROR 3 (HY000) at line 1: Error writing file
'/mnt/disk/tmp/MY0Wy7vA' (Errcode: 28 - No space left on device)
I have 11 GB free on disk and while the query is running, I keep track of it using
df -h
and
df -hi
to keep track of inodes
and I don't see any decrease in disk space while the query is running. All the time there is always 11 GB free on disk where the tmp folder is located.
This is the output of df -h:
ubuntu#ip-10-0-0-177:~$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 0 3.9G 0% /dev
tmpfs 799M 57M 742M 8% /run
/dev/xvda1 30G 24G 5.4G 82% /
tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/xvdf1 50G 39G 11G 80% /mnt/disk
tmpfs 799M 0 799M 0% /run/user/1000
This is the output of df -aTh:
Filesystem Type Size Used Avail Use% Mounted on
/dev/xvdf1 ext4 50G 39G 11G 80% /mnt/disk

Answer 1

Take a look at the part of the error that indicate it’s actually writing to /tmp (see below)
: Error writing file '/mnt/disk/tmp/MY0Wy7vA
In some Linux distributions, /tmp is mounted as a tmpfs (ramdisk), so even if your disk has plenty of space you can get a "no space" error if you try to write too much there.
To investigate about the mount, try
$ cat /proc/mounts
OR
$ cat /proc/self/mounts
Or better yet
df - aTh
df -h /tmp
To see hidden ones, try
du -sc * .[^.]* | sort -n
Among other things you can try making MySQL use a different temp directory, or to not use tmpfs for /tmp
If TMPDIR is not set in my.cnf, MySQL uses the system default which is usually /tmp
You can change the MySQL tmp dir as the following suggests:
Changing the tmp folder of mysql
Credits ::
https://github.com/LogBlock/LogBlock/issues/540