Ok, we all know how a key-value store is not competitive with the current SQL db's. But lets remember all of this NOSQL trend started with the SQL databases being a poor fit for a distributed environment back in the day.

By the way, what i would actually love to have, is a LINQ like API abstracted over a key-value store, and access to a SQL AST also in the language.. For me i think this is the desired middle ground, where you can scale and compose data over key-value, but also not to be stuck with SQL data mappings inside your codebase.

I mean, a relational algebra API that deal with any KV store, be it LINQ or the backend of something like Presto (or the DataFrame of Spark).

If you need something like a SQL interface somewhere, you could build it by stitching the SQL AST with the engine you use directly in the language.