[OSM-dev] [OSM-talk] Getting historic information about usage of a node

Tom Hughes tom at compton.nu
Wed Sep 16 01:06:22 BST 2009


On 16/09/09 00:49, Peter Körner wrote:

> But because Node #50 was deleted after Changeset #5 there is *no* way to
> fetch the ways this node was in. Same would happen if Way #10 would get
> deleted - the GET /node/#id/ways call just does not spit out any
> historic information. What we need would be a
>
>      GET /node/#id/#version/ways
>
> But i don't think this can go into the api without a major change..

There is no problem adding new methods to the API at any point in time.

The problem here is that I doubt it is possible to implement such a 
method in an efficient way - the necessary information just doesn't 
exist in the database.

You would basically have to do something like:

   - Find that node version in the nodes table

   - Find all way versions which have ever included that node
     in the way_nodes table

   - Look up those way versions in the ways table and match
     the timestamps against the node to see if they were using
     that version of the node or not

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/




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