[OSM-dev] Proposal: Database accelerator and dirty tile marker based on simple algorithm.

[Raphaël Jacquot]

Nick Hill wrote:
> I see a need for two additional dimensions to the underlying data 
> representation.
> 
> 1) A system to quickly determine if an area needs to be re-rendered. For 
> example, if an update has been made to an area.
> 
> 2) A system to speed the collection of data from the database.
> 
> Both of these goals can be achieved by representing the globe as virtual 
> tiles.
> 
> The tile which any object sits on can easily be determined as follows, 
> using only a few cheap CPU cycles, assuming lat and lon are 32 bit integers:
> 
> tile=(lat & 4294901760)+(lon>>16)
> 
> where & is bitwise and, and >> is right shift.
> 
> This will divide the world up into 6553.6uD tiles. On the equator, these 
> would be 655x655meters. If the whole planet were to be represented, this 
> would be 3.0174851x10E9 tiles of varying size. In reality, we'd probably 
> ever get to a few tens of million tiles given that much of the earth is 
> sea, arctic tundra and desert.
> 
> How will this help mark areas as updated?
> 

how about using this first ?

http://dev.mysql.com/doc/refman/5.1/en/creating-spatial-indexes.html