[OSM-talk] Mapnik tileset coherency issues

[Tom Hughes]

In message <220CB213-644D-446B-A291-D96CCBE3A847 at remote.org>
        Frederik Ramm <frederik at remote.org> wrote:

>> What I mean is, say a tile x,y,z is dirty and needs to be  
>> rerendered. You would include adjacent tiles on a given z , but  
>> also on lower z levels (say a dirty tile x,y at zoom level 12,  
>> would also mean all tiles contained by tile x,y at subsequent zoom  
>> levels 13,14 ... would be considered dirty in the same job). Could  
>> you render this batch of tiles than into a cache, before committing  
>> the whole batch to the live tileset, thus ensuring more consistency ?
>
> My understanding is that mapnik is so fast at rendering tiles that  
> rendering a whole tileset (level 12 and everything below it) could be  
> done in a time short enough as to not require any extra "buffering";  
> the inconsistent state would probably only exist for a few minutes.

The problem is that at busy times we can already have 100,000 tiles
queued for rendering, which is several hours worth. Automatically 
adding surrounding tiles and inferior/superior tiles will obviously
add to that.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/