ST_CoveredBy
Name
ST_CoveredBy — Returns true if no point in A is outside B
Synopsis
    
     boolean
     
      ST_CoveredBy
     
     (
    
    geometry
    
     geomA
    
    , geometry
    
     geomB
    
    
     )
    
    ;
   
    
     boolean
     
      ST_CoveredBy
     
     (
    
    geography
    
     geogA
    
    , geography
    
     geogB
    
    
     )
    
    ;
   
Description
   Returns
   
    true
   
   if no point in Geometry/Geography A lies outside
            Geometry/Geography B.
            Equivalently, tests if every point of geometry A is inside
            (i.e. intersects the interior or boundary of) geometry B.
  
       
      | 
     |
| 
       
       This function automatically includes a bounding box comparison
that makes use of any spatial indexes that are available on the geometries.
         To avoid index use, use the function
         | 
    
       
      | 
     |
| 
       
       Enhanced: 3.0.0 enabled support for
         | 
    
       
      | 
     |
| 
       Do not use this function with invalid geometries. You will get unexpected results.  | 
    
Performed by the GEOS module
Availability: 1.2.2
NOTE: this is the "allowable" version that returns a boolean, not an integer.
Not an OGC standard, but Oracle has it too.
Examples
  --a circle coveredby a circle
SELECT ST_CoveredBy(smallc,smallc) As smallinsmall,
  ST_CoveredBy(smallc, bigc) As smallcoveredbybig,
  ST_CoveredBy(ST_ExteriorRing(bigc), bigc) As exteriorcoveredbybig,
  ST_Within(ST_ExteriorRing(bigc),bigc) As exeriorwithinbig
FROM (SELECT ST_Buffer(ST_GeomFromText('POINT(1 2)'), 10) As smallc,
  ST_Buffer(ST_GeomFromText('POINT(1 2)'), 20) As bigc) As foo;
  --Result
 smallinsmall | smallcoveredbybig | exteriorcoveredbybig | exeriorwithinbig
--------------+-------------------+----------------------+------------------
 t            | t                 | t                    | f
(1 row)