It's not exactly a key-value store, but have a look at this: https://en.wikipedia.org/wiki/Temporal_database https://en.wikipedia.org/wiki/Temporal_database T

It's not exactly a key-value store, but have a look at this: https://en.wikipedia.org/wiki/Temporal_database https://en.wikipedia.org/wiki/Temporal_database Though, if I personally had this requirement, I would just roll my own as it sounds very basic and easy to represent in a plain RDBMS. No way am I going to base my DB choice/design or infrastructure impementation for something this small.