> The Problem

Imagine you have 10,000 files and want to determine which ones already exist on a Blossom server before uploading.

the bloom filter (& friends) approach works well if clients actually use them. i worked on an api that exposed offers/coupons to apps like foursquare/groupon/etc back in the day. given a course location, we’d return a promotion at a nearby merchant, if available. that calculation wasn’t cheap and you can imagine the amount of traffic given the clients. we mitigated much of the load by generating and shipping bloom filters to the clients. if there definitely wasn’t a promotion available, they’d skip the request.