Highly interesting article on Digg The Blog: Digg implemented their new badges feature in Cassandra, a distributed, structured key-value store also used at Facebook. — “When an item is dugg, we asynchronously populate Cassandra. This job fetches the list of followers of the digging user, and places one column in each of their buckets. This is a large amount of data for popular users. Kevin Rose, for example, has 40,000 followers. Thanks to Cassandra’s excellent write performance and batch operations, every column is inserted at once, atomically, in under a second.”