[OSM-dev] Quick History Service

Frederik Ramm frederik at remote.org
Sat Apr 23 21:29:13 BST 2011


    with the license change likely to occupy us for the next year or so, 
the question "who has edited this object, and have they all agreed to 
the new license?" will become more important for some use cases (most 
notably editors). If you're only interested in one or two objects then 
you can simply download thir history from the API and inspect that, but 
if you want to quickly colour your editor screen in red/yellow/green 
then that would probably overload the API.

I have built a narrowed-down database that keeps a list of all objects 
and their editors. Because it keeps nothing else (no concise object 
histories etc.), it is reasonably small and fast (the MySQL database 
takes 55 GB on disk for all objects). Data is updated every minute.

There's a minimalistic API that allows you to query the database:

For the impatient, here is an example request that should already 
explain how things work:


Documentation (with some important caveats!) and source code is 
available via http://wtfe.gryph.de/.

I intend to operate this service until something more usable comes along 
or until the license change is finished, whichever happens earlier. Feel 
free to poll this service from inside an editor after you have 
downloaded data from the OSM API.

I'm open to suggestions about improving the service (conditions apply: 
anything that requires re-importing the history file will lead to a 
three-day downtime, and anything increasing DB space by more than 30% 
will hit the limit of this particular host). But anyone is welcome to 
use the source and set up their own servers, too.


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