[ww520]

This is an excellent write up on Roaring Bitmap. The concrete examples really help to illustrate the algorithm well.

While Roaring Bitmap performs well on space saving with good performance, my gut feeling is there're better ways to achieve the same goals, especially it involving sorting on insertion and binary search on lookup, both on the sorted top level list and the sorted lower-bit integers.

Also it works well on 32-bit integers and probably 64-bit integers but it's not clear it can scale well beyond to bigger integers.

Nevertheless it's an excellent algorithm that works well in practice.