MySQL Error: SQLSTATE[HY000]: General error: 3 Error writing file '/tmp/xxxx.csv' (Errcode: 28)

if you happened to see the error as following, when you are running MySQL select ... into outfile "/tmp/xxxxx.csv";

 SQLSTATE[HY000]: General error: 3 Error writing file '/tmp/xxxx.csv' (Errcode: 28)

checkout your /tmp folder space in your linux, you will find your space is not enough for the file you are going to put into /tmp folder

to check,

shell> df -h