But really, you use one bitmap for each binary bit of an integer, and it turns out you can generate arbitrary range queries on your dataset by doing various combinations of boolean operations on those bitmaps.
> Pilosa is built around the concept of representing everything as bitmaps.
What this literally means is that not a single datum is stored that is not in the bitmap.
But then the diagrammed examples look like this:
manatee loris sea_horse
Vertebrate 1 1 1
Invertebrate 0 0 0
Breathes Air 1 1 0
If those strings are removed, the bitmap means jack squat.
Are they understood to be in another bitmap?
Sometimes this is a function which might map (for example) row 3 to the letter 'd', 4 to 'e', and so on. Sometimes it has to be a lookup table which can be kept within Pilosa, or externally. Sometimes the IDs map directly to what they represent (day-of-month, year, passenger count, etc.)
So strictly speaking, not everything is a bitmap, but the bulk of the heavy lifting in terms of serving queries is computation on bitmaps.