Performance gains from database level caching

[1mike12]

First off, I'm very new to using caches so pardon my misudnerstandings. But I was comparing the web server middleware level caching where entire paths are cached vs this library where we are caching at the ORM level. But from what I read, most dbs have an internal caching layer as well. I imagine the amount of time the database writers spent making the cache efficient and intelligent for most workloads is not insignificant. So how much faster can we get from adding another cache layer in front of the db cache layer? Theoretically it doesn't seem to add much benefit. But this library exists and there's lots of users, so what is it like in the real world?