ST_Contains(geog, geog) gives wrong answer

[pramsey]

create table gpoints (id integer, g geography);
insert into gpoints values 
  (1, 'POINT(-120.585938 55.195313)'), 
  (2, 'POINT(116.367188 57.656250)');
select 
  st_astext(g), 
  st_covers('POLYGON((-128.3203125 61.171875, -103.7109375 -54.140625, 72.0703125 0.3515625, 134.296875 15.8203125, 17.2265625 71.3671875, -6.328125 75.5859375, -128.3203125 61.171875))'::geography,g) 
from gpoints;
select 
  st_astext(g), 
  st_covers('POLYGON((-124.453125 64.6875, -127.6171875 -46.0546875, 51.6796875 -18.6328125, 46.0546875 -9.84375, 47.8125 17.2265625, 50.9765625 32.34375,-124.453125 64.6875))'::geography,g) 
from gpoints;

This appears to be similar to #562, where the point-in-polygon routine was failing because the generated "point outside" the polygon actually wasn't outside. In the second example, and outside point simply cannot be generated and everything stops.

I fear that as polygons get bigger, the question of what they "bound" comes into sharp relief in a way that is less problematic for small polygons. While most geodata is small enough to be obviously containing the "smaller" part of the sphere, it's trivially easy to generate a large polygon using a global mercator map in a GUI. Click, click, click, and you have a query polygon that visually covers most of the globe.

[pramsey]

Slight improvement in 1.5 at r5851, trunk at r5852

[pramsey]

Visualization of input polygon and candidate points

 http://www.gcmap.com/mapui?P=61.171875N+128.3203125W+-+54.140625S+103.7109375W%0D%0A54.140625S+103.7109375W+-+0.3515625N+72.0703125E%0D%0A0.3515625N+72.0703125E+-+15.8203125N+134.296875E%0D%0A15.8203125N+134.296875E+-+71.3671875N+17.2265625E%0D%0A71.3671875N+17.2265625E+-+75.5859375N+6.328125W%0D%0A75.5859375N+6.328125W+-+61.171875N+128.3203125W%0D%0A120.585938W+55.195313N%0D%0A116.367188E+57.656250N%0D%0A&MS=wls&DU=mi

[pramsey]

The improvement has removed the total failure from the second case. The answers may still be "wrong" depending on how you interpret the containment region of the polygon.

[pramsey]

Nowhere to go from here.