[postgis-users] Multipolygons UNION

[Brent Pedersen]

On Nov 16, 2007 4:20 AM, Kirill Zinov <kirill.zinov at gmail.com> wrote:
> Hello,
>
> I'm newbie with PostGIS and would like to ask to point me to a right
> direction. I need to unite all of the multipolygons that have the same
> attribute and that are contiguous to each other. Actually I need to
> unite the sub-divisions like the States in the US and keep the islands
> apart from the mainland.
>
> I tried this query but it fails:
>
> INSERT INTO country (the_geom, na2)
> SELECT astext(multi(geomunion(the_geom))) AS the_geom, na2 FROM polbnda
> GROUP BY na2;
>
> Please advise how to do this.
>
> Kirill
>
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hi, i've been able do that following strk's example here:
http://postgis.refractions.net/pipermail/postgis-users/2003-October/003236.html
but i dont know what your multi() call does.