[OSM-dev] Optimal free compression algorithm for OSM XML data

David Earl david at frankieandshadow.com
Wed May 30 10:19:12 BST 2007



> -----Original Message-----
> From: dev-bounces at openstreetmap.org
> [mailto:dev-bounces at openstreetmap.org]On Behalf Of Nick Hill
> Sent: 10 May 2007 09:26
> To: OSM-dev
> Subject: [OSM-dev] Optimal free compression algorithm for OSM XML data
>
>
> After a brief discussion at the developers conference in Oxford regarding
> compression algorithms for planet.osm, I decided to perform a
> series of tests
> using different algorithms available in free software.


Nick - just a thought, but if you want to reduce the download size, why not
produce a (compressed) planet diff from the previous week's planet. This
will be a relatively small download, which the user can then apply with
merge and should get the original back. The overall time may not be much
different because fo the time to apply the merge, but badwidth consumption
will be much reduced. This would have to be n addition to the full planet
file, of course, because you have to start sometime with a complete file.

David





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