Log All Queries in MongoDB using Database Profiler

Enable logging queries until restart

mongo -u username -p password
use myDb
db.setProfilingLevel(2)

Profiling Status

> db.getProfilingStatus()
{ "was" : 2, "slowms" : 1, "sampleRate" : 1 }

Starting in MongoDB 4.4.2, you can set a filter to control which operations are logged by the profiler.

Enable logging queries permanently

nano /etc/mongod.conf

Log queries take more than 1 mills to run :

operationProfiling:
   mode: all
   slowOpThresholdMs: 1
   slowOpSampleRate: 1.0

Log queries with filter :

operationProfiling:
   mode: all
   filter: '{ op: "query", millis: { $gt: 2000 } }'

Change Size of system.profile Collection on the Primary

The <database>.system.profile collection stores database profiling information.

To change the size of the system.profile collection on the primary, you must:

For example, to create a new system.profile collection that is 4000000 bytes (4 MB), use the following sequence of operations in mongosh:

db.setProfilingLevel(0)

db.system.profile.drop()

db.createCollection( "system.profile", { capped: true, size:4000000 } )

db.setProfilingLevel(1)

References
https://stackoverflow.com/questions/15204341/mongodb-logging-all-queries
https://stackoverflow.com/questions/18510966/why-the-queries-inside-the-system-profile-collection-are-being-overwritten
https://www.mongodb.com/docs/manual/tutorial/manage-the-database-profiler/
https://www.mongodb.com/docs/manual/reference/configuration-options/