[Tile-serving] [openstreetmap/osm2pgsql] pgsql-mid fails on relations with more than 32767 members (#713)

[mboeringa]

@lonvia ,

Out of interest, I have loaded the particular changeset in JOSM.

For completeness sake, especially in relation to your remarks about the ill-adviced import you made on the mailing list (Which can be read here on GIS Nabble: http://gis.19327.n8.nabble.com/osm2pgsql-update-failure-insert-rel-failed-td5892960.html), I think it fair to the OSM community member(s) who initiated this and uploaded the offending relation, to list the discussion and import proposal.

As it turned out after the loading of the changeset, the data has been imported by (a member of) the Brazilian community, based on the following e-mail list post dated the 9th of March, and a Wiki import proposal referenced by it:

https://lists.openstreetmap.org/pipermail/talk-br/2017-March/012063.html
https://wiki.openstreetmap.org/wiki/Importa%C3%A7%C3%A3o_das_Redes_Geod%C3%A9sicas_do_IBGE

Actually, there doesn't seem to have been proper discussion, as the original post doesn't seem to have any follow up...

Based on knowledge of Italian and some Spanish, I can make out the import, which constitutes the geodetic base network of Brasil imported as nodes, as also witnessed by the **man_made=survey_poin**t tag on all nodes, was mainly done to facilitate better alignment of aerial photography and objects to digitize using a solid reference, and to help identify remote locations and villages. 

By itself, if the data has been released in full accordance with OpenStreetMap license, I can imagine this being of use to a community like the one in Brasil.

The actual problem arose because the thousands of individual nodes were grouped into relations representing individual geodetic networks. The Wiki import page mentions this intention to create relations for these networks (which indeed was ill-adviced...)

Maybe it would be good to advice the community both about import guidelines, but also, if the data is in accordance with OSM, to not create relations of them, but instead just tag individual nodes with the network reference, so they can be identified (and potentially selected) as belonging to a certain network in OSM tools like JOSM or Overpass Turbo.

The sheer number of nodes (tens of thousands) by itself should pose no issue for OSM or import tools. Just grouping them in a relation is problematic.

**Lastly:**
All of this also raises another more general issue: it is likely more people might consider a similar action on **nodes**. While it is highly unlikely relations of ways will exceed >32k members, relations for grouping of nodes, as witnessed by this particular import of a geodetic network, could easily exceed this figure.

This really gives food for thought about how to handle future incidents...

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