Pretty much anything you'd like to do with CouchDB or MongoDB. Replace "document based storage" with table based and you have pretty much any *SQL application.
So I guess my question is: How do you expect people to use your fine grained model with databases? If the answer is "not at all" then I find the scope too limiting. If the answer is "1 grain == 1 db" then I find the claim that you are solving difficult permission problems to be false.
Note: I don't want to be too critical here, I'm just trying to pick holes in your claims of scope so I can categorise the power of sandstorm and how far it could be useful for things I'd like to build.
> Pretty much anything you'd like to do with CouchDB or MongoDB
Wekan is a Trello clone that uses MongoDB for storage. On Sandstorm, each board lives in a grain, so there ends up being one MongoDB per board. This works fine. The only thing stand-alone Wekan ever did that queried multiple boards at once is display the user's list of all boards. On Sandstorm, displaying the user's grain list is Sandstorm's job, not Wekan's -- and indeed, usually the user is more interested in seeing the list of all their grains rather than just the Wekan boards, so delegating this to Sandstorm is a UX win.
If that is not the kind of example you have in mind, then you really need to give a specific example.
So I guess my question is: How do you expect people to use your fine grained model with databases? If the answer is "not at all" then I find the scope too limiting. If the answer is "1 grain == 1 db" then I find the claim that you are solving difficult permission problems to be false.
Note: I don't want to be too critical here, I'm just trying to pick holes in your claims of scope so I can categorise the power of sandstorm and how far it could be useful for things I'd like to build.