[OSM-dev] Augmented Diffs
Roland Olbricht
roland.olbricht at gmx.de
Mon Aug 27 20:28:31 BST 2012
Hi Paweł,
> This looks really good and may be useful for a project that I'm working
> on.
>
> Quick question - have you considered adding relation members data to
> these diffs?
Yes, I have considered it. The reason not to do this so far are the really
huge relations. Examples for these are national borders (relations 51477,
1111111 and several other), trans European routes (e.g. relation 2148361) and
potentially similar relations.
If we do the simplest approach to handle relations exactly like ways, we get
3.5 MB of minute diff in all minutes when a single node in these relations is
moved (and much more if several relations are involved). Also, this would
really produce heavy load on the server.
So what I need towards relations is an approach that is simple to understand,
reasonable concerning the leverage of processed data, and that fulfills the
need of potential consumers.
Things I have considered but not deemed easy enough to understand are to make
it dependand on a certain tag in the relation, on the number of the relations'
elements or not do deliver nodes when delivering unchanged ways because they
are members of changed relations. It is all unsatisfactory, so good ideas are
welcome.
Best regards,
Roland
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