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<p class=MsoNormal><span lang=EN-US>Hello,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>I am looking for some help in optimizing a
query.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>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.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>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.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Here’s the query :<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>SELECT ST_area(ST_GeometryFromText('POLYGON((-1
0, -1 1, 1 1, 1 0, -1 0))', 4326) ) -<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>(SELECT
SUM(st_area(st_intersection(the_geom, ST_GeometryFromText('POLYGON((-1 0, -1 1,
1 1, 1 0, -1 0))', 4326) ) ))<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> FROM
tests WHERE the_geom && ST_GeometryFromText('POLYGON((-1 0, -1 1, 1 1,
1 0, -1 0))', 4326) )<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>=> if query returns 0 then my polygon
can be fully covered if != 0 then it can’t.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>But I was wondering if there couldn’t
be an easier way to do this.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Thank you.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Nicolas.<o:p></o:p></span></p>
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