Monitoring slow queries on large database (Percona 5.6)
You can use pt-query-digest --processlist
While there are four different ways to use it, IMHO the best way to use it is to poll the processlist and collect metrics every hour. This method does not need a slow query log.
I have suggested this before (See mysql 5.7 general_log table has user_host but the file does not)
I have promoted this idea many times over the years.