The point of DBaaS is that you wrap an open source database with a proprietary control plane that you won't release. Cloud vendors say this is compliant with AGPL but database startups say it isn't and thus the cloud vendors need to buy a license.
None of those pages you linked say anything like that, you're just making stuff up.
One of them is not the company talking about their license choice but a FUD article crying about AGPL which we've seen a million tired versions of.
The Rethink one says
> * Require users who choose to modify RethinkDB to fit their needs to release the patches to the software development community.
> * Require users who are unwilling to release the patches to the software development community to purchase a commercial license.
note:
> * who choose to modify RethinkDB
and
> * release the patches
none of these say anything about problems with putting control planes in front of it.
I have worked with cloud hosting a database where the only feature behind the enterprise license is a load balancer with some dead simple authz plugins.
You can write put any LB in front of it and host and sell it with the same capabilities without violating the OSS license.
Adding a "control plane" that sits in front of the hosted database does not require you to publish any modifications unless you actually are running a modified version of the open source software. You would never have to publish your own LB.
