[postgis-users] I'm missing something

Tue May 20 13:44:17 PDT 2008

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
>>>> _______________________________________________
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>>>>
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