Hi, author of the article here.

Just to give a little more background here.

Cabin doesn't store a row in a database for each visit. It only stores one row, per day per domain. The attributes for that row are simple tally counts - visits, uniques, bounces etc. So no identifier is stored, and the hits go into the tally. We do not store the fact that a user has visited x amount of times. The demo here is to show how the technique works.

Cabin used to detect only the presence of any last-modified date to determine if the visit is unique or not. But extending it to distinguish hits 1,2 and 3 (by adding 1 second to the start of the day) now allows us to count the bounce rates too.