[OSM-dev] Daily diff's retry

Robert (Jamie) Munro rjmunro at arjam.net
Sat Oct 13 13:48:58 BST 2007


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Luka Frelih wrote:
>> I updated osmosis to the latest version and checked my cron script to
>> produce daily diffs with osmosis. If things work out, there should be
>> daily diffs out there on planet.openstreetmap from now on. No promises
>> that it will work though :-).
>>     
>> The file naming scheme is a little complicated and I take suggestions for 
>> better ones.
>
> how about producing diffs for each full calendar day (UTC), running the 
> job a short time after midnight?
> it seems a bit more predictable and then the naming scheme could simply 
> be YYYY-MM-DD-planet.osc.bz2?

That sounds like a much better idea to me. It could run at 10 past
midnight, but only include changes up to midnight. Presumably it will be
named with the day it covers, which will always be one day earlier than
the day it is made.

Could we run it more often than daily? Perhaps hourly, with filenames
YYYY-MM-DDTHH:XX-planet.osc.bz2? Each hourly file would be generated at,
say 2 minutes past the next hour and include all the changes that
occured in the hour that it is named. The XX is meant to indicate "all
minutes". This leaves the system open to have HH:MX for 10 minute
changesets and even HH:MM for 1 minute changesets, but I think 10 minute
changesets will be the highest resolution worth doing.

>> Now people don't have a reason anymore to complain about too long intervals 
>> between updates; take the daily diffs and make your maps current!

> is there already some code which generates a list of dirty tiles from 
> such a diff?

Perhaps this could be done by the zappy or mapnik database servers as
they merge the changes in.

If we can get mapnik to know when tiles need deletion, it could cache
tiles a lot longer and not need to redraw the same tiles ever week, just
in case they have changed.

Robert (Jamie) Munro
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