My understanding is that each module (Photos, Notes, etc) has its own feed which gets aggregated to create the main News feed. If each module is responsible fo

My understanding is that each module (Photos, Notes, etc) has its own feed which gets aggregated to create the main News feed. If each module is responsible for producing its own feed, it seems like this problem isn't too difficult to solve. Couldn't you just cast this as a search engine problem? You create a term vector with your social graph, and the corpus you are "searching" is people who updated their profile photo in the last 24 hours. You could compute the inverted index offline once an hour. http://en.wikipedia.org/wiki/Inverted_index http://en.wikipedia.org/wiki/Inverted_index