I've been attempting these operations using WKB not text.
Perhaps, that's the problem.
Bob
----- Original Message -----
From: "Kevin Neufeld" <[EMAIL PROTECTED]>
To: "PostGIS Users Discussion" <[email protected]>
Sent: Tuesday, May 20, 2008 2:07 PM
Subject: Re: [postgis-users] I'm missing something
I don't receive an error when merging your geometries together.
create table tmp (geom geometry);
insert into tmp values ('MULTILINESTRING((46 34.25,80 34.25))'::geometry);
insert into tmp values ('MULTILINESTRING((80 34.25,80 60))'::geometry);
insert into tmp values ('MULTILINESTRING((46 60,46 34.25))'::geometry);
select astext(st_union(geom)) from tmp;
astext
------------------------------------------------------------------------
MULTILINESTRING((46 60,46 34.25),(80 34.25,80 60),(46 34.25,80 34.25))
(1 row)
-- Kevin
Bob Pawley wrote:
I've attached an sql dump of the table tank_lin.
Hope this helps.
Bob
----- Original Message ----- From: "Paul Ramsey"
<[EMAIL PROTECTED]>
To: "PostGIS Users Discussion" <[email protected]>
Sent: Tuesday, May 20, 2008 1:21 PM
Subject: Re: [postgis-users] I'm missing something
Attach the shape file to a bug in the bug tracker and I will have a
look.
http://code.google.com/p/postgis/issues/list
P
On Tue, May 20, 2008 at 1:12 PM, Bob Pawley <[EMAIL PROTECTED]> wrote:
They are three lines that, on Quantum GIS, display as a flat U - a
simple
tank. Using either tank_lin or process_dgn tables - exactly what I
imported
using dxf2postgis.
'Select as text' returns three rows each with the expression
"Multilinestrings" followed by brackets and coordinates.
'Select St_Union' returns - unknown geometry error.
Are you thinking there is something wrong with the installation?
Bob
----- Original Message ----- From: "Obe, Regina"
<[EMAIL PROTECTED]>
To: "PostGIS Users Discussion" <[email protected]>
Sent: Tuesday, May 20, 2008 11:51 AM
Subject: RE: [postgis-users] I'm missing something
Are these big geometries? What does
SELECT ST_AsText(the_geom)
FROM tank_lin;
Also just to rule out its the table you are inserting into - does the
Union without inserting work?
Select ST_Union(the_geom)
from tank_lin;
________________________________
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Bob
Pawley
Sent: Tuesday, May 20, 2008 2:11 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] I'm missing something
Hi Regina
It gives me three rows each with the expression "ST_MultiLineString"
with nothing else.
Bob
----- Original Message ----- From: Obe, Regina
<mailto:[EMAIL PROTECTED]>
To: PostGIS Users Discussion
<mailto:[email protected]>
Sent: Tuesday, May 20, 2008 10:56 AM
Subject: RE: [postgis-users] I'm missing something
Bob,
Strange. I don't think I have ever seen quite that error before.
What does
SELECT ST_GeometryType(the_geom)
FROM tank_lin;
give you?
Regina
________________________________
From: [EMAIL PROTECTED] on behalf of
Bob Pawley
Sent: Tue 5/20/2008 1:07 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] I'm missing something
I tried this -
Insert into graphics.process_dgm(the_geom)
Select ST_Union(the_geom)
from tank_lin;
and got the error "Unknown geometry type: 0"
Bob
----- Original Message -----
From: "Paul Ramsey" <[EMAIL PROTECTED]>
To: "PostGIS Users Discussion"
<[email protected]>
Sent: Tuesday, May 20, 2008 9:51 AM
Subject: Re: [postgis-users] I'm missing something
You don't want the GROUP BY. It is grouping the union op on
distinct
geometry... ie, one per row. Remove it and you'll get what you
want,
one output row.
P
On Tue, May 20, 2008 at 8:49 AM, Bob Pawley <[EMAIL PROTECTED]>
wrote:
Hi
I am attemptijng to use the ST_Union function to collapse
three rows from
a
table called tank_lin into one row in table called
process_dgm.
Here's what I used -
Insert into graphics.process_dgm(the_geom)
Select ST_Union(the_geom)
from tank_lin
Group by tank_lin.the_geom;
The result is three rows inserted into process_dgm, each row
appearing to
be
simple copies of each of the original rows.
I also attempted group by another column but received error
'unknown
geometry'.
I also tried STR_LineMerge with similar results.
What am I not considering?
Bob
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