Is it really about light vs. heavy though? I thought it was mostly about multiplexing notifications through a single app (usually through a single connection as well), so only one app has to consume resources constantly, and others might be activated as needed.
It's a little bit of both. You want to only keep one connection open as it minimizes the amount of network activity for e.g. keepalives. You also don't want the app holding that connection open to drain the battery in the process though.
> I mean, isn't the appeal of a relational DBMS that it is a black box to the user and it's the query planner's job to yield an efficient search for a given goal?
Just for the record, in Russia, we write all identifiers in English and practically all comments in (sometimes broken) English as well. Russian comments seem heavily discouraged, but hey, it's possible there're places where there're not.
systemd doesn't imply installed and running systemd-resolved though. I believe it's usually not enabled by default.