> Florian Lohoff wrote: > > On Fri, Sep 12, 2008 at 08:20:18AM +0200, Andreas Kalsch wrote: > > > >> Subject: Re: [OSM-dev] Spatial vs. multi-column indexes for points > >> > >> > >>> On Thu, Sep 11, 2008 at 08:31:23PM +0200, Andreas Kalsch wrote: > >>> > >>>> All, thanks for your quick responses! > >>>> > >>>> Quad tiles look like a smart way to create an index. So to lookup a > >>>> single point or a quad tile, this is fine. But for my application I > >>>> need another lookup - by bounding box with any ratio and size. Is > >>>> there a way to look up a special bounding box with this index? I > >>>> think this will be a little more complicated without conventional > >>>> multi-column indices. Hmm, I think you could take a maximum number > >>>> of quad lookups which contain the requested box, what do you think? > >>>> > >>> The code in the api calculates all possible quadtile areas and does a > >>> quadtile in ( x, y, z, a, b, c, d, e, f ) or quadtile between x and y > >>> etc > >>> > >> Can you give me the position of this code in SVN, I am sure will > understand it more deeply then. > >> > > > > applications/utils/export/osm2ai/osm2ai.pl > > > > Is a perl variant - look for "sql_for_area" > > > > In the rails_ports its done with a C helper - look in > > > > sites/rails_port/lib/quad_tile/ > > > or for the rails version > http://trac.openstreetmap.org/browser/sites/rails_port/lib/quad_tile.rb > > Shaun >
Thanks! And this really outperforms a simple query like "... latitude between y1 and y2 and longitude between x1 and x2" ? I will use 2^24 tiles as length. It looks like "tiles_for_area" goes through all tiles which are in the bounding box. So if I have an area with e.g. 5x5 kilometers, it will loop through 2000x2000 = 4 Million tiles. And so the SQL for this are will be quite big, won't it? Or am I totally wrong now? ;) -- GMX Kostenlose Spiele: Einfach online spielen und Spaß haben mit Pastry Passion! http://games.entertainment.gmx.net/de/entertainment/games/free/puzzle/6169196 _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
