[kazinator]

This page perpetrates an apparent contradiction. Starts off with:

> 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

Pardon my ignorance, but I see here a bitmap of 9 bits plus six character strings that are obviously not inside that bitmap.

If those strings are removed, the bitmap means jack squat.

Are they understood to be in another bitmap?

[jaffee]

One does have to maintain some understanding of the how integer row and column ids are linked to what they actually represent.

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.