Confusion about mongodb's slow query log

Question

I've read mongodb official manual and many other resources, but I still have some confusion about where the slow queries are logged in mongodb. Is it logged in the *.log file (the file that is specified by systemLog.path) or in system.profile collection?

And is there any difference between setting "operationProfiling.mode" parameter to "all" and db.setProfilingLevel(2);?

Answer 1

等待大神答复