This. To me, Redis was always about the rich set of operations you can atomically perform on data without going full ACID. It's very different from a pure cache (although it's probably a good choice if all you need is a cache).

Yeah. I do think that Redis has suffered from some mission creep, including a deprecated misadventure in to a mode where values could be stored on disk and only temporarily cached in memory.

Maybe that's what Cal and his colleagues were using it for at the time, but the claim that it started as a volatile cache is just not true. Interesting datastructures and the fork based persistence model were there from the start.

It started as a memcached with persistence to disk for fast startup.

No, it was always about data structures.

Lists, hashes, sets and such that you have available in your programming language, but available as a networked server so any language/app/process can access the same data using the same useful structures.