People think Redis is just a cache because the use the puggified version sold by AWS (elasticache). Enable persistence + AOF (the write ahead log) and you got yourself a database.
You can also add your own data structures to Redis, not as a form of syntax sugar over KV pairs, but as a dynamic library that you can write in C/C++/Zig/Rust, where you have full control over the in-memory representation.
But that's also another feature AWS takes away from you if you buy elasticache :^)
I definitely don't consider redis a database since it's not acid compliant and any data you put in you have to be OK with losing. It's still just a cache to me.
You can also add your own data structures to Redis, not as a form of syntax sugar over KV pairs, but as a dynamic library that you can write in C/C++/Zig/Rust, where you have full control over the in-memory representation.
But that's also another feature AWS takes away from you if you buy elasticache :^)