MYSQL大数据表联查（20W*20W）时报错, 小表查询正常，检查MYSQL服务器error.log:
210420 10:24:12 [ERROR] /usr/sbin/mysqld: Sort aborted: Error writing file '/tmp/MYxJWWvV' (Errcode: 28)
#查看详细MYSQL错误日志：
vi /var/log/mysql/error.log
210420 10:22:20 [ERROR] /usr/sbin/mysqld: Sort aborted: Error writing file '/tmp/MY0buVRE' (Errcode: 28)
210420 10:22:22 [ERROR] /usr/sbin/mysqld: Incorrect key file for table '/tmp/#sql_1ecb_0.MYI'; try to repair it
210420 10:22:22 [ERROR] Got an error from unknown thread, /build/mysql-5.5-xFqLis/mysql-5.5-5.5.60/storage/myisam/mi_write.c:226
210420 10:22:23 [ERROR] /usr/sbin/mysqld: Sort aborted: Error writing file '/tmp/MY21PWvi' (Errcode: 28)
210420 10:24:12 [ERROR] /usr/sbin/mysqld: Sort aborted: Error writing file '/tmp/MYxJWWvV' (Errcode: 28)
查询MYSQL-ERRCODE:28 可知磁盘空间不足，检查服务器可知磁盘正常：
@see perror命令
#检查ERROR:28错误原因：(No space left on device 磁盘空间不足)
root@DemoA:~# perror 28
OS error code 28: No space left on device
root@DemoA:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/DemoA--vg-root 15G 13G 839M 94% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
udev 3.9G 4.0K 3.9G 1% /dev
tmpfs 799M 532K 798M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 3.9G 0 3.9G 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 236M 220M 4.0M 99% /boot
overflow 1.0M 4.0K 1020K 1% /tmp
/dev/sdc 9.8G 48M 9.2G 1% /mnt
经查BAIDU+BING+GOOGLE，发现可能为缓存目录不够导致TMPDIR="/tmp"，只有1M，大表查询可能会出现磁盘不足错误，深入检查并实验后解决此问题：
# 增加磁盘挂载+100M到TMPDIR： 因为业务特殊原因不能修改/tmp目录位置
mount -o remount,size=100M tmpfs /tmp
# 检查挂载是否成功：/tmp -> 100M [OK]
root@DemoA:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/DemoA--vg-root 15G 13G 839M 94% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
udev 3.9G 4.0K 3.9G 1% /dev
tmpfs 799M 532K 798M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 3.9G 0 3.9G 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 236M 220M 4.0M 99% /boot
overflow 100M 4.0K 100M 1% /tmp
/dev/sdc 9.8G 48M 9.2G 1% /mnt
重启MYSQL服务器进行验证
service mysql restart
查询成功！问题解决！
