Real (Great Circle) distance in PostGIS with lat/long SRID?

Question

I'm using a lat/long SRID in my PostGIS database (-4326). I would like to find the nearest points to a given point in an efficient manner. I tried doing an ORDER BY ST_Distance(point, ST_GeomFromText(?,-4326)) which gives me ok results in the lower 48 states, but up in Alaska it gives me garbage. Is there a way to do real distance calculations in PostGIS, or am I going to have to give a reasonable sized buffer and then calculate the great circle distances and sort the results in the code afterwards? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

You are looking for ST_distance_sphere(point,point) or st_distance_spheroid(point,point). See: http://postgis.refractions.net/documentation/manual-1.3/ch06.html#distance_sphere http://postgis.refractions.net/documentation/manual-1.3/ch06.html#distance_spheroid This is normally referred to a geodesic or geodetic distance... while the two terms have slightly different meanings, they tend to be used interchangably. Alternatively, you can project the data and use the standard st_distance function... this is only practical over short distances (using UTM or state plane) or if all distances are relative to a one or two points (equidistant projections).