>There was a much-hyped database a few years ago that failed to live up to the hype because of exactly that architecture. The only database I can remember that

>There was a much-hyped database a few years ago that failed to live up to the hype because of exactly that architecture. The only database I can remember that did something like this was FoundationDB. They had the core layer as a K/V, and a layer above that was FSQL or similar. They got acquired by Apple, and most of their material was taken off line. I don't know if they were a failure (IIRC, some people were pretty impressed with the core NoSQL DB), but an exit to Apple may not have been all bad - although I would bet that Apple is not using the technology internally. IME, my beef with the new NewSQL solutions is that they tend to be worse at both NoSQL and SQL workloads (specifically none are "the best" at OLAP and OLTP) except at one specific use case - global-replication. Getting global replication requires a cost (either monetary like Spanner, or performance wise like everything else), and global-replication just doesn't seem like a killer feature to me. Most times I need data in two datacenters globally, I wouldn't replicate the data anyways (don't want EU data in the US), and other times my SLAs just aren't tight enough to warrant the cost.