Skip MySQL temp table

I have a problem where MySQL has taken a long time to copy the data to a temporary table.
I found a solution at:

http://stackoverflow.com/questions/7532307/skip-copying-to-tmp-table-on-disk-mysql

But in this problem, I changed the / tmpfs to / dev / shm.
More information about the / dev / shm can be found here

http://www.cyberciti.biz/tips/what-is-devshm-and-its-practical-usage.html

Step I:

1. Change the configuration of MySQL to use / dev / shm as temp tables directory

2. Change tmp_table_size = 2K