download http options: is it possible to do an union of all osmIds ?

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Hi all,


On an other osm boundaries site, i use to play with the union=true variable.

So that if i choose 2 osmIds, i can download only one polygone and not the 2 of them. Is this possible with https://osm-boundaries.com/Download/ ?

thank you and regards ;)

f.

ps: well, i guess, some doc are missing for the use of the api or i didn't find it.

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Magnus
  • Under review

Do you know what his union parameter did? I used his site as well, but don't recall what options it had. I just found the ones I needed and then used the same ones for years.

Did it do a union on all the provided IDs? That sounds like something that could be extremely expensive, especially on the land-only polygons. Just to get some form of estimate I just started a query to join (union) all the 21 admin-level 4 in Sweden. I would expect that to take over an hour, but that's a very rough guess.

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fabrice régnier

I'm not sure how it worked on https://wambachers-osm.website
Because i know  nothing about osm polygones. The only thing i remember is that the result of this union was quite fast too.


Here is an example that i've used to get only polygone despite i have two ids

https://wambachers-osm.website/boundaries/exportBoundaries?cliVersion=1.0&cliKey=blablabla&exportFormat=json&exportLayout=single&exportAreas=water&union=true&selected=140383,215328

Maybe we can ask Walter the webmaster of the ancient site ?

regards,


f.

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Magnus

It might depend on the data. 31 polygons around where I live took 0.9 second to join. Those 21 admin-level=4 of Sweden took 12m 21s.

If you had a single polygon as the end result it probably was an ST_Union. We will consider that for future releases. But we will have to figure out a way to avoid having queries running for weeks.

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fabrice régnier

thank you @Magnus !

pls, let us know when this new feature is done, will you ? ;)

regards,


f.

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Magnus

We will keep this topic open until it's either implemented or decided not to be. Any feedback, like the fact that it's implemented, will be show here.