Hi, Could someone help me understand a behavior I see when trying to union some HLL sketches?
I have 14 HLL sketches, and I know the exact unique counts for each of them. All the individual sketches give estimates within 2% of the exact counts. When I try to create a union, using the default lgMaxK parameter results in total estimate that is way off (25% larger then exact count). However, reducing the lgMaxK parameter in the union to 4 or 5 gives results that are within 2.5% of the exact counts. Also, one particular sketch seems to cause the final estimate to jump - not adding that sketch to the union keeps the result close to the exact count. Am I just seeing a very bad random error, or is there anything I'm doing wrong with the unions? Running on Java, using version 1.3.0. Just in case, the sketches are in the linked gist (hex encoded, one per line): https://gist.github.com/mmusnjak/c00a72b3dfbc52e780c2980acfd98351 and the exact counts: https://gist.github.com/mmusnjak/dcbff67101be6cfc28ba01e63e41f73c Thank you! Marko Musnjak
