I’ve loaded a shapefile into PostGIS using ogr2ogr, but transformed it from it’s original SRS EPSG:3857 to CRS EPSG:4326
ogr2ogr -t_srs EPSG:4326 -lco GEOMETRY_NAME=geom -nln newyork -f PGDump /vsistdout/ newyorkstate.shp
I understand that PostGIS has Geography type and Geometry type columns. I assumed ogr2ogr would naturally create a table where “geom” would be of the Geography type because it’s WGS-84. I was suprised to see it’s actually a Geometry type column.
From my reading it seems the Geometry type column can store geometries without CRS(s) and even EPSG:4326.
My question: what does it mean for the underlying geometry units to have EPSG:4326 stored in a Geometry type column? Are they still degrees? Or are they now cast to meters?
Second question: what does this mean for operations that expect a Geometry type such as ST_Extent? Later on let’s say I want to use the ST_Extent function that takes a Geometry type. Do I need to cast to the Geometry type ( geom::geometry )? That seems redundant.