After running NC with NCP for more then a year with over 2 million files stored on it, I asked myself if the mysql/mariadb DB needs to be maintained?
I searched the internet and the simplest solution I found was using

sudo mysqlcheck -o --all-databases

This reduced the DB size from around 950MB to a little over 800MB and NC seems to be a little more responsive (but this could homeopathic as well)

Any, would it make sens to extend NCP with an "DB Optimize" option?

5 Days after the optimization plus an upgrade to NC 16.0.4 I am still under 850MB. I am fetching the information via ocs_data_server_database_size provided by serverinfo.