> As it turns out, after I implemented the fractal tree, I spoke with a former employee of Tokutek, a company that commercialized fractal tree indices. That person told me that we’d actually implemented fractal reads identically!
That's not necessarily a good thing. Last I heard Tokutek patented that. Not a laywer, from what I understand patents specifically pertain to "implementation".
Not sure what happened after they were acquired by Percona, but, as I am in US I would personally stay away from it. Even if current owner doesn't want to enforce the patent, the next one might.