ST_Intersects
Name
ST_Intersects — Returns TRUE if the Geometries/Geography "spatially intersect in 2D" - (share any portion of space) and FALSE if they don't (they are Disjoint). For geography -- tolerance is 0.00001 meters (so any points that close are considered to intersect)
Synopsis
    
     boolean
     
      ST_Intersects
     
     (
    
    geometry
    
     geomA
    
    , 
						geometry
    
     geomB
    
    
     )
    
    ;
   
    
     boolean
     
      ST_Intersects
     
     (
    
    geography
    
     geogA
    
    , 
						geography
    
     geogB
    
    
     )
    
    ;
   
Description
If a geometry or geography shares any portion of space then they intersect. For geography -- tolerance is 0.00001 meters (so any points that are close are considered to intersect)
Overlaps, Touches, Within all imply spatial intersection. If any of the aforementioned returns true, then the geometries also spatially intersect. Disjoint implies false for spatial intersection.
Enhanced: 2.5.0 Supports GEOMETRYCOLLECTION.
Enhanced: 2.3.0 Enhancement to PIP short-circuit extended to support MultiPoints with few points. Prior versions only supported point in polygon.
Performed by the GEOS module (for geometry), geography is native
Availability: 1.5 support for geography was introduced.
       
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       This function call will automatically include a bounding box comparison that will make use of any indexes that are available on the geometries.  | 
    
       
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       For geography, this function has a distance tolerance of about 0.00001 meters and uses the sphere rather than spheroid calculation.  | 
    
       
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       NOTE: this is the "allowable" version that returns a boolean, not an integer.  | 
    
   
    
   
   This method implements the
   
    OpenGIS Simple Features
 Implementation Specification for SQL 1.1.
   
   s2.1.1.2 //s2.1.13.3
			  - ST_Intersects(g1, g2 ) --> Not (ST_Disjoint(g1, g2 ))
  
   
    
   
   This method implements the SQL/MM specification. SQL-MM 3: 5.1.27
  
   
    
   
   This method is also provided by SFCGAL backend.
  
Geometry Examples
SELECT ST_Intersects('POINT(0 0)'::geometry, 'LINESTRING ( 2 0, 0 2 )'::geometry);
 st_intersects
---------------
 f
(1 row)
SELECT ST_Intersects('POINT(0 0)'::geometry, 'LINESTRING ( 0 0, 0 2 )'::geometry);
 st_intersects
---------------
 t
(1 row)