If you need to know which queries require long time, you can activate the mysql log for slow queries.
To activate we need to edit the config file. On ubuntou you can use
# Log log_slow_queries = /var/log/mysql/mysql-slow.log long_query_time = 2
MySQL needs to be restarted. On ubuntu you can try
The log file will be created when mysql matches a long query with the time specified.
There is a tool to extract from the log file. Try the following
mysqldumpslow /var/log/mysql/mysql-slow.log -s c -t 10
Or use the classic tail to see live new entries.
tail -f /var/log/mysql/mysql-slow.log
- have fun -