Problem with Mapserver Virtual Spatial Data (ogr)

Fri May 19 02:42:26 EDT 2006

OGR tries to automatically detect the primary key of a table. This does not
always work automatically. The reason could be for instance the data type
used for your primary key, or maybe a small flaw in the driver's code.
Another example, using ODBC on Access, there is trouble detecting the
primary key because of a not implemented ODBC function in the Microsoft
driver. 

Best regards,
Bart

-----Oorspronkelijk bericht-----
Van: UMN MapServer Users List
[mailto:MAPSERVER-USERS at LISTS.UMN.EDU]Namens Christian Wilmes
Verzonden: vrijdag 19 mei 2006 8:40
Aan: MAPSERVER-USERS at LISTS.UMN.EDU
Onderwerp: Re: [UMN_MAPSERVER-USERS] Problem with Mapserver Virtual
Spatial Data (ogr)

Hi Frank,

thank you very much for your help!

With the line
CONFIG "PGSQL_OGR_FID" "fieldname" 
in the Map section everything works very well.

But now I've still got one more question, just an understanding one. I've
got testet the "Virtual Spatial Data" with a MySQL Database a few days ago
and there everything works well without a line like that. Where could be the
reason?

Best Regards
Christian

-------- Original-Nachricht --------
Betreff: Re: [UMN_MAPSERVER-USERS] Problem with Mapserver Virtual Spatial
Data (ogr)
Datum: Thu, 18 May 2006 16:55:40 -0400
Von: Frank Warmerdam <warmerdam at POBOX.COM>
An: MAPSERVER-USERS at LISTS.UMN.EDU

> Christian Wilmes wrote:
> > Hello,
> > 
> > first of all sorry for cross posting, but I've got no idea where I have
> to
> > search the mistake so I post it to the GDAL and the Mapserver
> Mailinglist.
> > 
> > I'm trying to publish a WFS-Server. The Data (only Point-Data) are in a
> > PostgreSQL-Database (no PostGIS!). So the connection to the data is over
> > "Virtual Spatial Data". The getCapabilities and DescribeFeatureType
> request
> > both work very well. Only the GML-Document getting with the getFeature
> > request is not correct. The number of features in the GML-Document are
> > correct too every time, but the features are not in the Bounding Box.
> The
> > features in the GML-Document are always the feature which are on the top
> of
> > the table they come from. Only the number of feature is correct. The MBR
> > (Minimum Boundig Rectangle) on the top of the GML-Document amasingly the
> > correct one. So it don't fit to the features in the document. Testing
> the
> > connection with "ogrinfo" and a Boundig-Box is working correct. If I'm
> > trying to make a WMS-Server with the same Data and the same OGR-file it
> > works very well.
> 
> Christian,
> 
> I believe the problem is that OGR is not successfully identifying a column
> in the table to use as a "feature id".  For WFS queries the results are
> fetched in two passes for various historical reasons.  The first pass
> results in a fetch of the feature ids of the features, and the second
> pass fetches features by id.  Unfortunately, if OGR cannot select a good
> unique feature id column, then it assigns them serially.  The first pass
> has the spatial query "in place" so the resulting fids are 1, 2, 3, etc.
> But the second pass does not have the spatial filter in place, so it ends
> up returning the wrong features.
> 
> Ideally you would ensure you have a single integer column setup as a
> primary index for your postgres table.  If that is the case it *should*
> get used as the fid.
> 
> If not, you may be able to include the following line in your MAP file
> (in the MAP section, not the layer):
> 
>    CONFIG "PGSQL_OGR_FID=fieldname"
> 
> to indicate what fieldname should get used as FID.  This should be
> available with GDAL/OGR 1.3.2.
> 
> PS. the much talked about one-pass-query would resolve this problem.
> 
> Good luck,
> -- 
>
---------------------------------------+------------------------------------
--
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGF, http://osgeo.org

-- 

Bis zu 70% Ihrer Onlinekosten sparen: GMX SmartSurfer!
      Kostenlos downloaden: http://www.gmx.net/de/go/smartsurfer

Disclaimer
************************************************************************
Aan dit bericht kunnen geen rechten worden ontleend. Dit bericht is
uitsluitend bestemd voor de geadresseerde. Als u dit bericht per abuis
hebt ontvangen, wordt u verzocht het te vernietigen en de afzender te 
informeren. Wij adviseren u om bij twijfel over de juistheid of de 
volledigheid van de mail contact met afzender op te nemen.

This message shall not constitute any rights or obligations.
This message is intended solely for the addressee.
If you have received this message in error, please delete it and
notify the sender immediately. When in doubt whether this message
is correct or complete, please contact the sender.
************************************************************************

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/mapserver-users/attachments/20060519/158757d6/attachment.html