OpenStreetMap
I started re-defining a relation (osm.org/browse/relation/37300/) to map a cycle route found on a web site. I already did that relation two days ago (using podlatch as i'm too lazy to teach myself how to use JOSM). Today I looked back and the relation was still there but had no member ways |@#¼ anymore.
Is this a Podlatch bug or something ?
Абмеркаванне
Камэнтар Circeus ад 14 Кастрычнік 2008 у 23:29
The history of ways doesn't track addition or removal of relations. Maybe somebody was not too bright and did improper merges, or remover the relation from its elements?
Камэнтар Richard ад 15 Кастрычнік 2008 у 00:46
Are you sure it's missing? I can see it here: osm.org/edit?lat=50.59196&lon=4.61728&zoom=15&way=27695325
Камэнтар Circeus ад 15 Кастрычнік 2008 у 00:57
I was assuming he had to reconstruct it.
Камэнтар Richard ад 15 Кастрычнік 2008 у 01:18
Well, my best guess is that it's versions executing out of sequence. If you add a way to a relation, then do that (say) 10 times, that's fine if the server executes the first write (relation contains way A), then the second (contains A, B), then the third (contains A, B, C) and so on.
But if the first write takes a very long time getting through, which can happen, then it's possible the server will execute the tenth write (A,B,C,D,E,F,G,H,I,J), then the first (A). And if you leave Potlatch at that point then the first will be the live version.
Unfortunately there's not a whole lot that can be done about this until API 0.6. 0.6 will return version numbers with every read, and require them to be sent with every write, so it will be able to reject a write of version 1 after version 10. But right now Potlatch doesn't actually know the version of any object so there's no sensible way to add this check.
Камэнтар Richard ад 15 Кастрычнік 2008 у 09:55
Memo to self: close the italics tag. :) Anyway, thinking about it, there was a bug for a few hours in adding relations. Maybe this is what swiped it. Apologies if so.
Камэнтар Luc Moreau ад 15 Кастрычнік 2008 у 16:16
Yes Richard it was not missing but empty (containing no ways I believe or maybe just one remaining way - I don't remember). Anyway I started redefining it just after posting this diary entry and it didn't took me too long to do that. Looking at the time of your comment I had probably already finished.
Thanks for the explanations.