cockroach has a much more thought out model. See: https://www.cockroachlabs.com/pricing/
And the story is already clear and thought out in the license file and Makefile: https://github.com/cockroachdb/cockroach/blob/master/LICENSE
And the story is already clear and thought out in the license file and Makefile: https://github.com/cockroachdb/cockroach/blob/master/LICENSE
Reading your links, it's comforting that they've thought a lot about their licences and have differing (liberal) licences for various parts of their database.