I can attest that it is certainly possible to use a Key-Value store as a database in certain conditions. I created one myself to support adding metadata (tags)

I can attest that it is certainly possible to use a Key-Value store as a database in certain conditions. I created one myself to support adding metadata (tags) to objects in the file system replacement system I was designing. Each tag had a key (the object ID it was attached to) and a value (string, number, dateTime, location, etc.). Once I had it working and could attach hundreds of tags to each of the millions of data objects (Didgets); the whole system started to look like a sparse relational database table. So I used the tagging system to create tables and run queries against them. It turned out to be extremely flexible and fast. To my surprise, it could often outperform traditional DB systems like SQLite or PostgreSQL. https://www.youtube.com/watch?v=Va5ZqfwQXWI https://www.youtube.com/watch?v=Va5ZqfwQXWI