[OSM-dev] spatial index - B-Tree over z-order curves vs R-Tree over GIST

[pablo platt]

>
> I've not come across these terms but from your references it seems that
> this is very much the same as our "Quadtiles" approach.


According to this http://www.ddj.com/184410998 z-order curve is a case of
"Quadtiles".

The OSM db is still based on MySQL which has no multi-dimensional indexes
> either so we  added a "quadtree tile" to each node which allows indexing.
> Since this happens on the application layer of course it makes our select
> queries quite ugly ("where (tile > x0 and tile <x1) or (tile > x2 and tile <
> x3) or (...) ...") but they're not there to win a beauty contest and the
> parser hasn't complained. Yet.


Is the tiles resolution predetermined or is the tree dynamic and when a tile
get overpopulated you divide it to 4 child tiles?
I don't understand how you make a query in a dynamic tree.
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