[OSM-talk] Identical Duplicate buildings

[Ewen Hill]

Thanks Wayne for the quality investigative work,
   I note that the first two examples are from seasoned veteran OSM
editors. I am wondering if the issue is temporary when servers have been
under heavy load?

Ewen

On Sun, 31 Jan 2021 at 03:08, Wayne Emerson, Jr. via talk <
talk at openstreetmap.org> wrote:

> To analyze this situation I decided to check my local area and examine
> the problematic changesets in detail. So far I have found a few
> different scenarios:
>
> 1.) Duplicate ways uploaded in one changeset which took a long time to
> process.
> Changeset 92289777 created 65 duplicate parking spaces (created
> 2020-10-11 00:43:02; closed 2020-10-11 00:46:45) by the iD editor. We
> can see it took 3 minutes and 43 seconds for this changeset to upload
> which is unusually long)
> The 2 sets of duplicate parking spaces had a gap in their numbering
> sequence:
> Set 1 was numbered ID# w857666299 through w857666363
> Set 2 was numbered ID# w857666698 through w857666762
> These were the only new ways uploaded in this changeset.
>
> So I decided to check the way ID's that fell between the above sequences
> w857666364 from changeset 92289780 (created 2020-10-11 00:43:16; closed
> 2020-10-11 00:43:17)
> w857666697 from changeset 92289805 (created 2020-10-11 00:46:12; closed
> 2020-10-11 00:46:13)
> This helps us to see the timing of the 2 upload attempts of the duplicates:
> Set 1 was uploaded between 2020-10-11 00:43:02 and 00:43:16
> Set 2 was uploaded between 2020-10-11 00:46:13 and 00:46:45
>
> I have sent a message to the mapper of the changeset in question to see
> if they can recall what happened during their upload. But no response yet.
>
>
> 2.) Another set of duplicates I found were uploaded in 2 different
> changesets, 36 seconds apart by the iD editor.
> https://overpass-api.de/achavi/?changeset=76618180
> 2019-11-05 Created: 00:36:10 Closed: 00:36:11
> 4 ways deleted; 10 ways modified; 7 new ways
>
> https://overpass-api.de/achavi/?changeset=76618192
> 2019-11-05 Created: 00:36:47 Closed: 00:37:06
> 7 ways modified; 7 new ways(duplicates)
> Only 7 out 10 modified ways were re-uploaded. Each of the modified ways
> had the same tags & geometry as the previous changeset but still had
> their version number increased by 1.
> The 3 ways from the first changeset that were not re-uploaded:
> https://pewu.github.io/osm-history/#/way/569219081
> https://pewu.github.io/osm-history/#/way/568979084
> https://pewu.github.io/osm-history/#/way/214527867
>
>
> 3.) Potlach 2 created these duplicate ways
> Changeset: 75951029
> original: https://pewu.github.io/osm-history/#/way/737004106
> duplicate: https://pewu.github.io/osm-history/#/way/737376779
>
> Changeset: 76010386
> original: https://pewu.github.io/osm-history/#/way/737004108
> duplicate: https://pewu.github.io/osm-history/#/way/737360688
> In these 2 changesets the mapper moved the pre-existing swimming pools
> but they were uploaded as duplicates.
>
> Does this provide any more clues about what is going on? One possible
> conundrum for using a bot to remove duplicates is that some duplicates I
> found ( but not referenced above) were later added to relations, so a
> bot would need to pick the duplicate not in a relation to delete.
>
> -Wayne
>
>
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-- 
Warm Regards

Ewen Hill
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