Understanding Fusion Trees?

Question

I stumbled across the Wikipedia page for them:

Fusion tree

And I read the class notes pdfs linked at the bottom, but it gets hand-wavy about the data structure i

Answer 1

I've read the fusion tree paper. The ideas are pretty clever, and by O notation terms he can make a case for a win.

It isn't clear to me that it is a win in practice. The constant factor matters a lot, and the chip designers work really hard to manage cheap local references.

He has to have B in his faux B-trees pretty small for real machines (B=5 for 32 bits, maybe 10 for 64 bits). That many pointers pretty much fits in a cache line. After the first cache line touch (which he can't avoid) of several hundred cycles, you can pretty much do a linear search through the keys in a few cycles per key, which means a carefully coded B-tree traditional implementation seems like it should outrun fusion trees. (I've built such B-tree code to support our program transformation system).

He claims a list of applications, but there are no comparative numbers.

Anybody have any hard evidence? (Implementations and comparisons?)