It's key to remember that MySQLTuner is a script which can assist you with your server, but it is not the solution to a badly performing MySQL server. The best performance gains come from a thorough review of the queries sent to the server, and an evaluation of the MySQL server itself. A qualified developer in your application's programming or scripting language should be able to work with a MySQL database administrator to find improvements for your server. Once the server and application are optimized well, you may need to consider hardware upgrades to the physical server itself.
This is a really useful tool for helping to optimize MySQL performance.Understanding the various my.cnf variables and how they affect performance can seem really complicated but this tool takes some of the pain away and makes it easier to understand the effects of each variable.It is especially useful to be able to see the global memory usage, memory usage per thread and the maximum possible memory usage -- that is really valuable information that is otherwise complex to calculate.
Run MySQLTuner in Debian
Download MySQLTuner using the following command
To run the script, simply make it executable and run it:
chmod +x mysqltuner.pl
Enter your administrative username and password
Output you can see as follows
You need to check mainly recommendations section at the end. It shows which variables you should adjust in the section of your my.cnf (on debian file located at /etc/mysql/my.cnf).