[postgis-users] I need to simplify a table

José Vicente Higón Valero higon_jos at gva.es
Mon Oct 10 00:42:23 PDT 2005

Hi list,
I'm a beginner in postgis and I want to simplify a table in order to
serve a layer with full extent in mapserver.
I have done these steps with a table of multipoligons:

First, I reduce the table with Simplify function:
create table muni_simplify as (select gid,Simplify(the_geom,100) as
the_geom,provincias from muni_pol_10k)

Second, I group the records:

create table muni_collect as (select Collect(the_geom) as the_geom from
muni_simplify group by provincias)

Later, I try to export the created table to a shapefile but the
geometrycollection isn't support by pgsql2shp, how can I collect into
I can't use the function addGeometryType in the created
table 'muni_collect', why?.
How can I preserve de column gid in the collect operation?
Is my approach correct?

Thaks in advance.

  José Vicente Higón
  Grupo de desarrollo de gvSIG
  Conselleria de Infraestructuras y Transporte
  Generalitat Valenciana
  Valencia - Spain
  tlf. 963862397

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