Hallo look at ST_CoveredBy, ST_Covered, ST_Contain and ST_ContainProperlyin
dochttp://www.postgis.org/documentation/manual-1.4/
They all handle this questions in slightly different ways.I think all of them
will use any potential index, but look in doc to be sure. Hope that
helpsNicklas
2010-01-18 Nicolas Gillet - MARKET-IP wrote:
>
Hello,
I am looking for some help in optimizing a query.
I have a table with bounding boxes and sometimes I need to find if a new given
polygon can be fully covered by existing bounding boxes of my table.
Right now I can find it out by summing the areas of intersections between my
polygon and those in my table and comparing this computed area with my polygon
area.
Heres the query :
SELECT ST_area(ST_GeometryFromText('POLYGON((-1 0, -1 1, 1 1, 1 0, -1 0))',
4326) ) -
(SELECT SUM(st_area(st_intersection(the_geom, ST_GeometryFromText('POLYGON((-1
0, -1 1, 1 1, 1 0, -1 0))', 4326) ) ))
FROM tests WHERE the_geom &&
ST_GeometryFromText('POLYGON((-1 0, -1 1, 1 1, 1 0, -1 0))', 4326) )
=> if query returns 0 then my polygon can be fully covered if != 0 then it cant.
But I was wondering if there couldnt be an easier way to do this.
Thank you.
Nicolas.
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