MongoDB database schema design

Question

I have a website with 500k users (running on sql server 2008). I want to now include activity streams of users and their friends. After testing a few things on SQL Server it

Answer 1

I believe you should look at your access patterns: what queries are you likely to perform most on this data, etc.

To me The use-case that needs to be fastest is to be able to push a certain activity to the 'wall' (in fb terms) of each of the 'activity consumers' and do it immediately when the activity comes in.

From this standpoint (I haven't given it much thought) I'd go with 1, since 2. seems to batch activities for a certain user before processing them? Thereby if fails the 'immediate' need of updates. Moreover, I don't see the advantage of 3. over 1 for this use-case.

Some enhancements on 1? Ask yourself if you really need the flexibility of defining an array of consumers for every activity. Is there really a need to specify this on this fine-grained scale? instead wouldn't a reference to the 'friends' of the 'actor' suffice? (This would a lot of space in the long run, since I see the consumers-array being the bulk of the entire message for each activity when consumers typically range in the hundreds (?).

on a somewhat related note: depending on how you might want to implement realtime notifications for these activity streams, it might be worth looking at Pusher - http://pusher.com/ and similar solutions.

hth