How can I get the default zoom level to work in QGIS for geography types?

Question

Create a table like this, and then add it as a layer to PostGIS. It has one simple geography, a line.

CREATE TABLE foo AS
SELECT ST_GeogFromText(
  'LINESTRING(-122.27172 37.80345,-122.27172 37.81549)'
) AS highway;

You can even create an index on it if you think it matters,

CREATE INDEX hwidx ON foo USING gist ( highway );

You can see the line in WKT in the table,

                      st_astext                      
-----------------------------------------------------
 LINESTRING(-122.27172 37.80345,-122.27172 37.81549)

Here is the table definition,

       Table "public.foo"
 Column  |   Type    | Modifiers 
---------+-----------+-----------
 highway | geography | 

Yet, when I Zoom to Layer in QGIS, no joy! It just shows a blank screen. I am using QGIS 2.18.2.

Answer 1

Looks like (as of Jan 2017) there's no support for determining the extent of a layer with geography column types. From the source in (qgspostgresprovider.cpp):

QgsRectangle QgsPostgresProvider::extent() const
{
  ...
  if ( mSpatialColType == sctGeography )
    return QgsRectangle( -180.0, -90.0, 180.0, 90.0 );

So for geography types the layer extent is always the entire globe. If you cast the geography to a projected geometry (even casting to a geometry in epsg:4326 should work) it will work correctly.

You can find an open bug for this filed on 4/30/2015 here., Bug report #12677 (Open): Zoom to layer on PostGIS Table with geography type.