Before revision:  Under this natural metric, the celebrated HyperLogLog sketch of Flajolet et al. (2007 ) has an MVP approaching 6(3\ln 2-1)\approx 6.48 for estimating cardinalities up to 2^{64.
After revision:  Under this natural metric, the celebrated HyperLogLog sketch of Flajolet et al. (2007 ) has an MVP .