I am not sure if badge calculation is the bottleneck. Foursquare did say the calculation is why they have to keep everything in memory though. I just assumed th

I am not sure if badge calculation is the bottleneck. Foursquare did say the calculation is why they have to keep everything in memory though. I just assumed that they sharded by user to keep all of the user's check-ins in the user document and that they are doing calculation with that set of data.