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PostGIS 1.5.8 Manual174 / 3107.8.8 ST_CoveredByST_CoveredBy — Returns 1 (TRUE) if no point in Geometry/Geography A is outside Geometry/Geography BSynopsisboolean ST_CoveredBy(geometry geomA, geometry geomB);boolean ST_CoveredBy(geography geogA, geography geogB);DescriptionReturns 1 (TRUE) if no point in Geometry/Geography A is outside Geometry/Geography BPerformed by the GEOS moduleImportantDo not call with a GEOMETRYCOLLECTION as an argumentImportantDo not use this function with invalid geometries. You will get unexpected results.Availability: 1.2.2 - requires GEOS >= 3.0This function call will automatically include a bounding box comparison that will make use of any indexes that are available onthe geometries. To avoid index use, use the function _ST_CoveredBy.NOTE: this is the "allowable" version that returns a boolean, not an integer.Not an OGC standard, but Oracle has it too.There are certain subtleties to ST_Contains and ST_Within that are not intuitively obvious. For details check out Subtleties ofOGC Covers, Contains, WithinExamples--a circle coveredby a circleSELECT 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 exeriorwithinbigFROM (SELECT ST_Buffer(ST_GeomFromText(’POINT(1 2)’), 10) As smallc,ST_Buffer(ST_GeomFromText(’POINT(1 2)’), 20) As bigc) As foo;--Resultsmallinsmall | smallcoveredbybig | exteriorcoveredbybig | exeriorwithinbig--------------+-------------------+----------------------+------------------t | t | t | f(1 row)See AlsoST_Contains, ST_Covers, ST_ExteriorRing, ST_Within