Compressed IntSets

[dleppik]

EWAH, Roaring Bitmaps, or some other compressed bitmap format. Roaring is particularly nice because it can be done as a combination of other IntSet formats.

See: http://code.google.com/p/javaewah/ http://roaringbitmap.org/

A good overview of compression techniques is in "Sorting improves word-aligned bitmap indexes" (2014): http://arxiv.org/pdf/0901.3751v5.pdf