[jchrisa]

The Couchbase Mobile Sync Gateway tackles fine grained access control head on. Basically you write a function that stripes your data into channels, and manages access on a per channel basis.

There are a few things that are challenging to model this way, but for 80% of use cases it's the right simplification. Intro documentation: http://developer.couchbase.com/documentation/mobile/current/...

[david-given]

Sync Gateway looks very plausible... but having to run an extra server just as access control to the main database? That's so ugh.

It also looks like this requires me to annotate each document with ACLs. I was rather hoping to be able to just sync a view, so that changing the database would cause players with changed views to automatically resync. I'm not terribly happy with having to recalculate the views of all players and then update the ACLs of all documents manually on every database mutation; that's a lot of writes.

[jchrisa]

The database speaks a binary database protocol. The Gateway speaks websocket and http.

Access control is managed via channels, and you configure the gateway with a JS function that determines which channels a document belongs to, so you don't ACL annotations, the ACL is determined dynamically by your code at write time.

There's a tiny bit of write amplification as we persist channel membership in an index, but that's to avoid massive read amplification of irrelevant records when clients sync their subset of channels.