Find out slow sql of mysql

Recent days, I should do a sql tuning for a mysql database, and I know a bit of mysql db. In order to find the slow sql, i do the slow_query_log on to collect the slow sql.

mysql> show variables like 'slow%';+---------------------+-------------------------------------------+| Variable_name       | Value                                     |+---------------------+-------------------------------------------+| slow_launch_time    | 2                                         || slow_query_log      | ON                                        || slow_query_log_file | /opt/mysql_data/mysql/mysql-test-slow.log |+---------------------+-------------------------------------------+3 rows in set (0.00 sec)mysql> set global slow_launch_time=5;Query OK, 0 rows affected (0.00 sec)mysql> show variables like 'slow%';+---------------------+-------------------------------------------+| Variable_name       | Value                                     |+---------------------+-------------------------------------------+| slow_launch_time    | 5                                         || slow_query_log      | ON                                        || slow_query_log_file | /opt/mysql_data/mysql/mysql-test-slow.log |+---------------------+-------------------------------------------+3 rows in set (0.00 sec)

We can read  /opt/mysql_data/mysql/mysql-test-slow.log  to find slow sql.