That's a good breakdown. In this case though FoundationDB's KV store was order preserving. The API supported (& efficiently implemented) ranged reads, not jus

That's a good breakdown. In this case though FoundationDB's KV store was order preserving. The API supported (& efficiently implemented) ranged reads, not just individual get's. Implementing layered architectures always looks good 'on paper' but the details often throw up performance issues that are hard to deal with without punching some holes in the abstractions. In this case it seems that relatively few companies had a need for a massively scalable ordered KV store, and the whole SQL layer was an attempt to bridge the product to a wider audience. It would be fascinating to hear more of the story but I suspect that will never escape now.