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Hallo Atul,<br>
<br>
perhaps, I would split the query in two queries, because otherwise I
think it might be difficult to use a spatial index on the second
intersection. The queries could be like this:<br>
<br>
--create a spatial index on each input table:<br>
create index temp_outputtree_2_gist_geometry on temp_outputtree_2
using gist(geometry);<br>
create index temp_outputtree2_4_gist_geometry on temp_outputtree2_4
using gist(geometry);<br>
create index temp_outputtree_5_gist_geometry on temp_outputtree_5
using gist(geometry);<br>
<br>
--intersection of the first 2 tables using the spatial index,
writing the result of it into a new table:<br>
select st_intersection(t1.geometry,t2.geometry) as geometry into
new_table from TEMP_OUTPUTTREE_2 t1 inner join TEMP_OUTPUTTREE2_4 t2
on t1.geometry && t2.geometry where
st_intersects(t1.geometry,t2.geometry);<br>
<br>
--create a spatial index on the new geometries of the first
intersection:<br>
create index new_table_gist_geometry on new_table using
gist(geometry);<br>
<br>
--intersection with the third table:<br>
select st_intersection(nt.geometry,t3.geometry) as geometry from
new_table nt inner join TEMP_OUTPUTTREE_5 t3 on nt.geometry
&& t3.geometry where st_intersects(nt.geometry,t3.geometry);<br>
<br>
Hope that helps,<br>
<br>
Birgit.<br>
<br>
Am 23.11.2011 13:16, schrieb Atul Kumar:
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<p class="MsoNormal">Hi All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am trying to intersection multiple sets
of geographical data using ST_intersection function. But
query execution time is long.
<o:p></o:p></p>
<p class="MsoNormal">My Query is : <o:p></o:p></p>
<p class="MsoNormal">select st_intersection (st_intersection
(t1.geometry, t2.geometry), t3.geometry) geometry from
TEMP_OUTPUTTREE_2 t1,TEMP_OUTPUTTREE2_4 t2, TEMP_OUTPUTTREE_5
t3<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am having three table its having geometry
data. I want to intersect operation on those data.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please suggest, Is there any optimal way to
get the intersection with less execution time?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal">Atul Kumar<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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