On Sun, 10 Apr 2011, Jesper Krogh wrote:

On 2011-04-10 12:18, Oleg Bartunov wrote:
Wow, custom solution for 2008 still much faster Denali 2011  solution.
Also, what's about not spatial data types ? In our approach, we can provide knn for any datatype, which has GiST index and distance method.

Can you share some insight about how it would
work if the distance method is "expensive" (as in 100ms)?

I don't understand how does your question connected with my statement :)

Slow distance calculation affects gist-based ordered heap output  as well as
seqscan output from heap, but in the first case you need to calculate just a
few distances (something like height of gist tree), while in the naive way one have to calculate n^2 distances.

Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: o...@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83

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