Mostly the reason for this is that I'm using an agx without a screen to run rtabmap but can only visualize the database and run "rtabmap-databaseViewer" on my laptop that is a bit slow. So It would be more nice if I could write scripts on the agx for working with the database.
Here I actually also have a question. The agx is running melodic while the laptop is running noetic, could that be an issue? I mean sending the file back and forth, using it on ros-melodic but optimizing and changing it on the laptop. Or is the "rtabmap.db" file the same layout always?
rtabmap-databaseViewer does make it easier to add/remove/refine constraints, though you may be able to do it with a python script or shell script using sqlite3 directly on the database (like in link you shown).
If melodic is using an older rtabmap version than your noetic laptop, you can make changes on noetic and send it back to melodic. Newer versions of rtabmap are always backward compatible with all older rtabmap's database versions.