[OSM-talk] Identical Duplicate buildings

[mmd]

On 2021-01-28 22:53, Mike Thompson wrote:
> 
> 
> On Thu, Jan 28, 2021 at 2:41 PM Stephan Knauss <osm at stephans-server.de
> <mailto:osm at stephans-server.de>> wrote:
>     Maybe some hickup during upload tricks iD into thinking they hadn't
>     been
>     uploaded yet.
> 
> Did you happen to see my musings of how this might be possible if the
> upload process is interrupted?  I am not sure if that is what is really
> happening, but it seem that if the editor does not receive confirmation
> back from the server (Rails Port), but if the Rails Port did send such
> confirmation (because it did process the upload), then the editor might
> indicate that there are unsaved changes, and if the user does not check
> whether the features really are there, they may attempt to upload a
> second time, resulting in duplicate features.
> 

A few remarks:

Unlike JOSM, iD doesn't update local negative ids with new real object
ids it receives from the API, and simply starts a new session by loading
all data from the API again.

As this could result in reading some outdated data, iD introduced two
extra delays of 2.5s each to cater for potential database replication
delays (mostly for historic reasons).

If a user were to close a browser tab while the upload popup is still
showing up, chances are that the upload already finished. Still iD
updates its local storage rather late to mark the upload as successful.
Next time iD gets opened, the user can choose to either keep or discard
previous changes, which introduces a way for duplicate uploads.

Furthermore, duplicate uploads could be avoided by a mechanism called
"idempotent uploads". As there was no consensus on implementation
details, this feature isn't available at this time.

The changeset upload endpoint supports compressed uploads. Due to the ~
8x compression of XML data, working even on 2G mobile networks becomes
feasible. As of today, few  mobile editors like Go Map!! support
compressed uploads.

Changeset uploads are no longer handled by the Rails port since about
mid-2019.

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