Support PostGIS

[mnboos]

PostGIS shall be supported as mvt source.

[sfkeller]

Adding even more new sources is probably beyond the scope of https://github.com/geometalab/Vector-Tiles-Reader-QGIS-Plugin/projects/2 .

[tomchadwin]

I read a post about what is required to get ST_AsMVT working, but I'm damned if I can now find it. As I recall, connecting directly means you have to recreate functions which VT servers carry out themselves. An important example is scale-dependent geometry simplification.

There's a minimal Flask example here:

https://medium.com/@giohappy/vector-tiles-postgis-and-openlayers-258a3b0ce4b6

[sfkeller]

And here's another Flask example: https://www.zimmi.cz/posts/2017/serving-mapbox-vector-tiles-with-postgis-nginx-and-python-backend/ .

I really think that optimally PostGIS is just another source like GeoServer #112 and both just need to have a remote TileJSON metadata file, pointing to these ZXY tile sources.

[tomchadwin]

Another argument for wontfix: if the user has access to the database, they don't need to use VT to open the data in QGIS - they can just query without ST_AsMVT.

[sfkeller]

Agreed.

For the records: PostGIS is - or will be - supported via several servers and generators compatible with Mapbox vector tile (MVT). Examples are t-rex, tilemaker, and eventually GeoWebCache/GeoServer. So, this MVT plugin can consume already PostGIS VT with it's Connection dialog.

I'm remaining open to include this in future plugin development. This could probably be a useful feature for those who want to use QGIS as a frontend to PostGIS. Obviously, this makes more sense if queries really take e.g. scale/zoom into account which makes SQL queries more complex than just calling ST_AsMVT.

AFAIK there are still no established "SQL / PostGIS patterns" around, as following blog posts suggests: https://carto.com/blog/inside/MVT-mapnik-vs-postgis/#conclusions and https://carto.com/blog/inside/postgis-performance/ . But perhaps I'm unaware of further developments - besides OMT https://github.com/openmaptiles/postserve - and @rafatower or @pramsey could comment on this?

[mtravis]

Sounds like a great plugin. Look forward to testing it out.

On 26 Nov 2017 12:49 pm, "Stefan" [email protected] wrote:

Agreed. So closing this issue for now.

For the records: PostGIS is - or will be - supported via several servers and generators compatible with Mapbox vector tile (MVT). Examples are t-rex, tilemaker, and eventually GeoWebCache/GeoServer. So, this MVT plugin can consume already PostGIS VT with it's Connection dialog.

I'm remaining open to include this in future plugin development. This could probably a useful feature for those who want to use QGIS as a frontend to PostGIS. Obviously, this makes more sense if queries really take e.g. scale/zoom into account which makes SQL queries more complex than just calling ST_AsMVT.

AFAIK there are still no established "SQL / PostGIS patterns" around, as following blog post suggests: https://carto.com/blog/inside/ MVT-mapnik-vs-postgis/#conclusions . But perhaps I'm unaware of further developments and @rafatower https://github.com/rafatower or @pramsey https://github.com/pramsey can comment on this.

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