[OSM-dev] planet.openstreetmap.org/replication policy

[mmd]

Am 28.11.2016 um 15:28 schrieb Martin Koppenhoefer:
> 
> 2016-11-28 14:33 GMT+01:00 Oliver Tonnhofer <olt at bogosoft.com
> <mailto:olt at bogosoft.com>>:
> 
>     It would also not reduce the bandwidth by much, as it still needs to
>     download the same data.
> 
> 
> 
> it surely will use a lot fewer connections, but also the amount of data
> to download can be significantly smaller, depending how often the same
> objects get touched within the same day.
> 

I don't think that's the case. Daily diffs contain every single version
of an object as long as it has been created/deleted/modified on that
particular day. Maybe you're somehow confusing this with the Overpass
API augmented diffs, which in fact leave out all 'intermediate' versions.

You can easily check this for yourself, see relation id 3227136 or way
id 448670397 in:

http://planet.openstreetmap.org/replication/day/000/001/514.osc.gz

I think the only difference with minutely diffs vs. daily diffs is the
fix cost associated to transferring a single file. While that's not much
of a concern for a single daily diff file, downloading many small
minutely diff will for sure accumulate lots of fix cost and make the
whole process quite slow. Also, it creates more server load.

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