Re: WIP: Fast GiST index build

I've added information about testing on some real-life dataset to wiki page. This dataset have a speciality: data is ordered inside it. In this case tradeoff was inverse in comparison with expectations about "fast build" algrorithm. Index built is longer but index quality is significantly better. I think high speed of regular index built is because sequential inserts are into near tree parts. That's why number of actual page reads and writes is low. The difference in tree quality I can't convincingly explain now.

I've also maked tests with shuffled data of this dataset. In this case results was similar to random generated data.