[postgis-users] Problem with slow GeomUnion (geom, geom)

[Matt Doughty]

Hi,

 

I'm having some problems with the GeomUnion (geometry, geometry)
function- basically that it takes forever and eventually crashes out for
lack of memory. 

 

I'm trying to perform a union on two polygon tables (of 9,000 and 200
rows respectively), which are indexed on the geometry column, and
vacuumed too. The command I'm trying to run is: 

 

SELECT 

            table1.name AS t1_name,

            table2.name AS t2_name,

            GeomUnion(table1.the_geom, table2.the_geom) 

INTO

            table_union

FROM 

            table1, table2;

 

>From what I can gather, it shouldn't be that demanding. In Kosmo the
same operation takes less than 30 seconds (although it only lets you
maintain the attributes from one of the tables). Is it just that the
function takes a very long time or should I perform other functions
before carry out the GeomUnion??

 

 

All help greatly appreciated!!

 

Matt

 

 

 

Matt Doughty

 

GEOGRAMA S.L.

Tel.:  +34 945 13 13 72    652 77 14 15

Fax: +34 945 23 03 40 

www.geograma.com

 

 

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