com.liveramp:hyperminhash (maven):  HyperMinHash is a probabilistic data structure that can approximate union, intersection, and set cardinalities as well as Jaccard indices of very large sets with high accuracy, in loglog space, and in a streaming fashion. 
Keywords: cardinality|cardinality-estimation|hyperloglog|hyperloglog-sketches|java|loglog|loglog-beta|minhash