Integrate storage of route relations with osm2pgsql

[kennykb]

The current mewthod of using on the 'slim tables' of osm2pgsql to generate the 'shieldroute' and 'shieldway' tables works well for a workflow that applies daily updates from GeoFabrik (a fairly common case for those who map less than the planet). It obviously cannot scale to minutely updates of a whole planet. Moreover, the developers of 'osm2pgsql' strongly deprecate accessing the slim tables, warning that their content may change without warning.

The SQL operations to create, update, or delete route relations are pretty trivial. The obvious possibility for handling minutely updates (and improving update performance on the less-frequent ones) would be to include an option in 'osm2pgsql' to keep these two tables in sync when the database is first imported and when diffs are applied.

[kennykb]

Floated a proposal to add the necessary changes to osm2pgsql. Now to see whether I can get enough information from the better informed to flesh out the open issues in the requirements.

[kennykb]

Alas, this turns out not to be feasible.

I've received a fairly definitive indication from the maintainers of osm2pgsql that it is simply the wrong tool for this use case.

Will have to replan.