[OSM-dev] Various OSM troubles

Joerg Ostertag (OSM Munich/Germany) openstreetmap at ostertag.name
Mon Jan 8 15:56:39 GMT 2007


On Monday 08 January 2007 16:36, Ludwig Max Brinckmann wrote:
> Does anyone know what the exact error is? As humble API users we only get
> the 500 error, there should be more in the OSM log.
>
> I have the slight suspicion that if this is due to some sort of
> (changeable) configuration value that upping that value will not actually
> impact the OSM server performance badly, as the overall load will probably
> _decrease_, because people will not try and try again to load a larger
> region to then cut down their requests to tiles smaller in individual
> extent, but the same overall. (I do not know how many times I tried to
> download an area that interested me as it seemed a transient error, before
> I decided to cut my losses and tile my request instead. Every time the
> server spent endless time before deciding that it was too big -- all that
> processing wasted in vain.)
>
> However there should be a check on the size, so that people do not
> regularly download the planet just to see it is too big to digest for them.
> Limiting requests to a tile size smaller than 1 arc degree square should
> not be too onerous and combined with a meaningfull error message should
> solve most of the problem. It is at least worth a try before bringing
> mirrored dbs and new servers into play.

Maybe one problem is, that there is no good algorithm to tell how long it will 
take to get a specified area. This completely depends on the amount of Data 
found in this area. As what I recall the algorith first takes all nodes in 
the specified area, then finds all segments for this list of nodes and then 
searches for all ways containing these segments.

On the other hand there is a limit in size, but you probably will only see it 
if you are in a not so well filled area like Africa, ...

-

Joerg




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