FoundationDB is an Apple thing, isn’t it? Might explain why. It feels kinda like they’ve put it out there and it just hasn’t had anyone with a marketing budget to push it along.
FoundationDB was the first publicly available distributed transactional KV on the market that I can recall. It wasn’t “open” though - always proprietary. They generated a lot of hype and good press for being this NoSQL DB that was all about ACID correctness in the age of “mongo is webscale (by writing to /dev/null)”. They had a demo showing impressive throughout on a low power cluster with no data loss during a power cycle. I think that despite generally impressive tech they had some trouble selling but did end up selling the company to Apple.
