PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual162 / 310Availability: 1.5.0 changed behaviorWarningThis operator has changed behavior in PostGIS 1.5 from testing for actual geometric equality to only checking forbounding box equality. To complicate things it also depends on if you have done a hard or soft upgrade which behavioryour database has. To find out which behavior your database has you can run the query below. To check for trueequality use ST_OrderingEquals or ST_Equals and to check for bounding box equality =; operator is a safer option.Examplesselect ’LINESTRING(0 0, 1 1)’::geometry ~= ’LINESTRING(0 1, 1 0)’::geometry as equality;equality |-----------------+t |The above can be used to test if you have the new or old behavior of ~= operator.See AlsoST_Equals, ST_OrderingEquals, =7.8 Spatial Relationships and Measurements7.8.1 ST_AreaST_Area — Returns the area of the surface if it is a polygon or multi-polygon. For "geometry" type area is in SRID units. For"geography" area is in square meters.Synopsisfloat ST_Area(geometry g1);float ST_Area(geography g1);float ST_Area(geography g1, boolean use_spheroid);DescriptionReturns the area of the geometry if it is a polygon or multi-polygon. Return the area measurement of an ST_Surface orST_MultiSurface value. For geometry Area is in the units of the srid. For geography area is in square meters and defaultsto measuring about the spheroid of the geography (currently only WGS84). To measure around the faster but less accurate sphere-- ST_Area(geog,false).This method implements the OpenGIS Simple Features Implementation Specification for SQL 1.1.This method implements the SQL/MM specification. SQL-MM 3: 8.1.2, 9.5.3