Bounding rectangle of a geography

Question

How to get a bounding box (in the form of a Polygon, or anything else where it's easy to extract the corner coordinates from) of a given Geography item? Something that would look like:

SELECT Boundary(geog) AS boundingBox FROM segments;

Where geog is a MULTILINE geography.

Seems like a trivial question, but my experience so far is limited and I did not have any luck with the docs (http://www.postgis.org/documentation/manual-1.5/reference.html ) Tried ST_Boundary and Box2D but they do not work on geographies.

Answer 1

Cast the geography to a geometry type and then call ST_Envelope on the geometry.

SELECT ST_Envelope(geog::geometry) as boundingBox FROM segments;