Useful tool to track slow queries, no need to do any coding, just need to change the MySql config :
gksudo gedit /etc/mysql/my.cnf
Search for "slow" and change the lines to
log_slow_queries = /var/lib/mysql/mysql-slow.log
long_query_time = 1
log-queries-not-using-indexes
Restart mysql
sudo service mysql restart
Run your applications, then any queries that take longer than 1 second will be stored in the log. This can be viewed with
sudo mysqldumpslow | more
This will display the slowest queries first. Useful to keep running while in production to optimise your system.
To see the queries with the actual data
sudo more /var/lib/mysql/mysql-slow.log
Credit and thanks to Laurent David @ TDM