Thanks for the FOSDEM link. I know the videos are out, but just looking at the schedule to find the interesting talks took more time than I wanted to spend on i

Thanks for the FOSDEM link. I know the videos are out, but just looking at the schedule to find the interesting talks took more time than I wanted to spend on it. (The conference became so huge.) Maybe Bjorn's talk has the answers, but would you mind explaining how histograms are easy to aggregate? Don't you need either fixed buckets or raw data to produce a new histogram over a different dataset? (I know there are tricks to get great estimates, but naturally every re-aggregation would add larger and larger +/- intervals, no?)