[postgis-users] Strange problem in classroom usage of PostGIS and GDAL

[Ari Jolma]

Hi,

Sorry for x-posting.

I've been running a course on a Windows classroom, teaching spatial SQL. 
It's mainly based on Paul Ramsey's excellent "Introduction in PostGIS" 
exercises that I've pulled out from Lausanne website. The client the the 
students use is mostly PgAdmin but Quantum GIS and Geoinformatica 
(GDAL+Perl+GTK, my own stack) is used in the last steps instead of 
Mapserver as in Paul's paper. The databases (each student has her own) 
are on a Linux server.

On some cases the data retrieval from the base to the GIS clients 
(PgAdmin seems to be ok) fails. The schema is retrieved (also the number 
of features is ok) ok but the data just does not appear - i.e. the OGR 
Layer is empty. In a couple of cases no data at all is shown, and in 
some cases full layers are ok but layers with SQL do not show. The 
behavior is quite puzzling and I can't explain it. I and the students 
who have been affected have checked rights, srids etc. many times. In a 
case I tried to pull data from my own database with my own user id into 
a student's session, and it did not work. In my own session I haven't 
noticed any problems. The problem seems to be with certain windows-sessions.

In first sessions I hit the max connections limit on the database but 
that was easy to fix.

Are there any situations, where GDAL don't get data from a remote 
PostGIS but it does not issue warnings?

Regards,

Ari
(follow-ups preferably to gdal-dev)

-- 
Prof. Ari Jolma
Geoinformatiikka / Geoinformatics
Teknillinen Korkeakoulu / Helsinki University of Technology
tel: +358 9 451 3886 address: POBox 1200, 02015 TKK, Finland
Email: ari.jolma at tkk.fi URL: http://www.tkk.fi/~jolma