After some significant work with Google App Engine's data store, I can't help but think that the question "What are use cases for No SQL technologies?" should b

After some significant work with Google App Engine's data store, I can't help but think that the question "What are use cases for No SQL technologies?" should be turned on its head. Instead, ask yourself "Do I need full SQL database"? For the typical web app, you can't really go wrong selecting MySQL or Postgres. However, you also can't really go wrong to pick something like GAE's data store either. Unless you need sophisticated dynamic reporting capabilities, a key/value store is actually easier to work with than a relational database. A static schema slows you down, but it is a price worth paying if you need to a powerful query language and aren't concerned about scaling.