[OSM-dev] [PATCH] osm2pgsql tile expiry

[Roeland Douma]

Awesome! I have been working on some tile expiring myself however I stumbled 
upon some problems that would increase the execution time dramatically. So I 
will check out your code!

However I am wondering is it possible to add a range of zoom levels? Since I 
probably want to erase zoom 10-18.

--Roeland

On Sunday 08 February 2009 11:23:45 Steve Hill wrote:
> I've been working on code to generate a list of dirty tiles while
> importing the deltas.  The attached patch introduces 2 new commandline
> options: "-e <zoomlevel>" and "-o <dirty tile list output file>".  So,
> specifying "-e 17 -o /tmp/dirty_tiles" when importing a delta will cause
> osm2pgsql to generate a list of all zoom level 17 tiles which the delta
> has made dirty and store it in /tmp/dirty_tiles.
>
> Proviso: for polygons, it currently takes a simplistic approach of drawing
> a bounding box around the whole polygon and marking every tile in the box
> as dirty.  If the bounding box is large (over 30x30Km) the polygon is
> treated as a line instead, so only the perimeter will be marked as dirty
> (this is so that huge polygons don't expire vast numbers of tiles and is
> based on the assumption that we probably aren't going to shade the area
> of massive polygons).
>
> The dirty tile list is maintained in memory as a binary tree and dumped to
> disk at the end of the run.
>
> I'm running this code on OpenPisteMap and it seems to be working ok.  Does
> anyone have any objection to me committing these changes to the
> OpenStreetMap subversion server?
>
>   - Steve
>     xmpp:steve at nexusuk.org   sip:steve at nexusuk.org  
> http://www.nexusuk.org/
>
>       Servatis a periculum, servatis a maleficum - Whisper, Evanescence