[hknmtt]

because you are comparing in-memory store with permanent storage. many kvdb can be run from memory if needed.

[jamesrr39]

Technically, all of them can, if you put the "persisted" storage in a directory on a ramfs or tmpfs mount :)

This might seem like a bit of a facetious comment, but it does have genuine use cases, e.g. unit tests, or for data that you can easily restore after a shutdown.