[postgis-users] I'm missing something
Kevin Neufeld
kneufeld at refractions.net
Tue May 20 14:42:51 PDT 2008
No, I get the same thing with WKB.
create table tmp (geom geometry);
insert into tmp values
('0105000000010000000102000000020000000000000000004740000000000020414000000000000054400000000000204140'::geometry);
insert into tmp values
('0105000000010000000102000000020000000000000000005440000000000020414000000000000054400000000000004E40'::geometry);
insert into tmp values
('01050000000100000001020000000200000000000000000047400000000000004E4000000000000047400000000000204140'::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)
As Regina asked, what version of PostGIS are u using?
select postgis_full_version();
Bob Pawley wrote:
> I've been attempting these operations using WKB not text.
>
> Perhaps, that's the problem.
>
> Bob
>
> ----- Original Message ----- From: "Kevin Neufeld"
> <kneufeld at refractions.net>
> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
> 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"
>>> <pramsey at cleverelephant.ca>
>>> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>>> 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 <rjpawley at shaw.ca> 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"
>>>>> <robe.dnd at cityofboston.gov>
>>>>> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>>>>> 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: postgis-users-bounces at postgis.refractions.net
>>>>> [mailto:postgis-users-bounces at postgis.refractions.net] 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:robe.dnd at cityofboston.gov>
>>>>> To: PostGIS Users Discussion
>>>>> <mailto:postgis-users at postgis.refractions.net>
>>>>> 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: postgis-users-bounces at postgis.refractions.net 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" <pramsey at cleverelephant.ca>
>>>>> To: "PostGIS Users Discussion"
>>>>> <postgis-users at postgis.refractions.net>
>>>>> 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 <rjpawley at shaw.ca>
>>>>>
>>>>> 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
>>>>>>> _______________________________________________
>>>>>>> postgis-users mailing list
>>>>>>> postgis-users at postgis.refractions.net
>>>>>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>>>>>
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