[Rebuild] Another issue to consider: Osmosis replication

Frederik Ramm frederik at remote.org
Thu Feb 16 19:52:39 GMT 2012


Hi,

(CC'ing this to Brett Henderson, Osmosis inventor+maintainer)

    most of you will be familiar with the standard way of running one's 
own replicated OSM database - all based on Osmosis' --rri task which 
automatically loads the hourly or minutely diffs since it was last run 
and does with them whatever you ask it to.

I've asked Grant for the figures today, and according to the access logs 
there seem to be approximately 150 replicated instances of OSM "out 
there" - the majority of them, one would assume, for rendering, but some 
do other things - for example, Matt Amos runs his "OWL" database off of 
such diffs, or MapQuest's Nominatim will likely do the same.

Many of these databases run on auto pilot - they just have Osmosis 
polling for new stuff all the time and if our server hands out something 
then they'll process it.

Now what happens after we change the license and boot up our servers?

Will we produce one gigantic "diff" that encapsulates all the changes we 
had to make to get from the last CC-BY-SA version to the first ODbL 
version of our database, so that these users can simply continue to 
gobble up our diffs and they will magically be ODbL after the switch?

Or do we tell them: This is all too complicated, you will have to kill 
your old databae and do a fresh import if you want to be on the ODbL train?

Is it even possible, legally, that there is someone out there who has 
our current database (which is licensed CC-BY-SA only), and we provide 
them with a diff that deletes 5% of their objects and modifies anohter 
5%, and after that their database has magically become ODbL?

If this isn't possible or feasible, then some of them will face quite a 
bit of work - someone running a world-wide nominatim would have to 
schedule about two weeks of data import time after the license change 
during which they would have to serve old data. Also, if sticking to the 
current mode of operations is not an option, then maybe we need to 
rename the download directories of everything so that we can make sure 
that there's not a CC-BY-SA database somewhere updating itself on auto 
pilot with new ODbL diffs, creating all sorts of trouble for everyone

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"



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