Implement global parameters as stamped elements
What do you think about changing the internal representation of the
data::StampedValueCollection and start tracking database identifiers of the global parameters. That way, instead of deleting the entire global config, you could delete a given parameter if it comes from the database (its id is non-zero). The existing configuration would be preserved. Admittedly, if the parameter is set in the file and the database, the parameter value set in the file will be lost and the default will be set for it. But, that's really no different than what would happen if you have the same subnet in both places and you delete the one from the database. Attention least we'd be consistent.