https://www.citusdata.com/blog/2017/12/22/distributed-count-vs-hyperloglog/
https://news.ycombinator.com/item?id=15988764
blog-post-distributed-count-hyper-log-log#sketch-algorithms1At larger scale sketch algorithms like HyperLogLog can be really effective. (Sketches are probabilistic algorithms which can generate approximate results efficiently within mathematically provable error bounds. blog-post-distributed-count-hyper-log-log#sketch-algorithms1