[Haskell] Pearls of Functional Algorithm Design question

I'm currently reading the excellent Haskell-based book "Pearls of Functional Algorithm Design".  I have a question about Chapter 2, the "surpassing problem". According to the book, "since join takes linear time, table is computer in O(n log n) steps". However, as far as I can tell, join takes linear time proportional to the number of elements in *table*, and the number of elements in table is potentially as large as n^2 where n is the length of the original list.  So it seems like a quadratic algorithm or worse, to me.  What am I missing? Thanks, Mark