HyperLogLog intersection


Is it possible to do set intersection arithmetic with druid?



Not directly. It is theoretically possible, however, to get the HLL results with context:{finalize:false} and do the HLL Intersection externally.

Be aware the certainty in your calculations gets bad pretty fast for intersections where the overlap is small compared to either set.

I should add this is assuming you MUST do HLL intersection, and cannot just do normal dimension AND filters.