> What _are_ the "correct" use cases for NoSQL? there are many and the different use cases for it that I know of aren't really connected by a theme or any crit

> What _are_ the "correct" use cases for NoSQL? there are many and the different use cases for it that I know of aren't really connected by a theme or any criterion that can be generalized. this is my own observations only, and not a statement based on theory. the wisdom of experience. take it for what it's worth. 1. application state persistence. persisting the app state in something closer to its native representation (JSON, for example) is convenient sometimes. if all you really want to do is save the state and then reload it later in another session you've got a strong use case for some kind of NoSQL. Note that application state persistence is very different than object state persistence. The app state is specific to a single user at a single point in time. Object state might have multiple users (anyone that can manipulate that object) and multiple points in time (e.g. objects that are persisted for long periods of time). 2. Key:Value store for cacheing. this is the most basic, canonical use case. Memcached, redis, etc. 3. data structures that SQL is poorly suited for. Graphs and Trees come to mind. if you find your SQL schema suddenly becoming bogged down in M2M through tables, you probably have a good use case for a Graph oriented datastore. 4. Time series. arguably this is just a subset of relational data, or a domain specific language extension over traditional SQL, but still, it feels a little different in practice.