In the real world, it is extremely hard to provide all the same guarantees you get out of a single instance of <database vendor> if you turn around and spread it across the internet.
If you have super deep control over the physical & temporal environment around your system, you can cheat the rules a little bit (i.e. Google).
CockroachDB has an explicit clause is the licensing: Yes, employees and contractors can use your internal CockroachDB instance as a service, but no people outside of your organization will be able to use it without purchasing a license: https://www.cockroachlabs.com/docs/v21.1/licensing-faqs.html....
NGL, I've had to explain to enough people by now that the "funny name" is because it was made by ex-Googlers with a view towards resiliency, as per the idiom that only cockroaches will survive global nuclear war.
https://github.com/citusdata/citus
(Citus engineer)
So not (IBM-System-)R-compatible, then?