[GRASS-user] PostGIS MULTIPOLYGON table causes GRASS to crash

[Garbin, David]

I have a PostGIS table that was loaded from a shapefile which contained
multipolygons.  I've used v.external to connect to the shapefile
directly and it displays fine.  When I use the PG: driver to connect to
the database table, the display crashes when I tell it to Zoom to the
selected map extent.  Looking at the underlying SQL commands that
d.frame -e generates, it seems to be using a cursor to FETCH 500 records
at a time, but keeps looping back and fetches the same 500 records over
and over again.  The display mechanism works fine using the PG: driver
and a table that contains simple POLYGONS.

David A. Garbin 
Senior Fellow
Noblis
3150 Fairview Park Dr S
Falls Church, VA 22042
Phone:  +1 703.610.2050
Cell:     +1 703.795.6010
Email:   david.garbin at noblis.org

-----Original Message-----
From: Garbin, David 
Sent: Wednesday, August 22, 2007 10:44 AM
To: Garbin, David; Frank Warmerdam; Spencer Fogg
Cc: grassuser at grass.itc.it
Subject: RE: [GRASS-user] "Random read is not supported by OGR for this
layer, cannot build support."

We tried the patch to gdal that was suggested, but it did not work.  The
PostGIS table is owned by me and has a primary index, but the "Random
read..." error is still reported.  I worked around this by modifying the
Vect_build_ogr method (found in lib/vector/Vlib/build_ogr.c) to remove
the test.  That solved this problem and the simple topology was built in
GRASS with a link to the database.

I had other problems displaying the table that I was working with, but I
will report that in another thread.

David A. Garbin 
Senior Fellow
Noblis
3150 Fairview Park Dr S
Falls Church, VA 22042
Phone:  +1 703.610.2050
Cell:     +1 703.795.6010
Email:   david.garbin at noblis.org

-----Original Message-----
From: grassuser-bounces at grass.itc.it
[mailto:grassuser-bounces at grass.itc.it] On Behalf Of Garbin, David
Sent: Monday, August 06, 2007 3:52 PM
To: Frank Warmerdam; Spencer Fogg
Cc: grassuser at grass.itc.it
Subject: RE: [GRASS-user] "Random read is not supported by OGR for this
layer,cannot build support."

We will pursue this route here at Noblis where Spencer worked over the
summer.  Our folks who installed the gdal libraries will be in touch,
probably next week as we will be out of town this week.  Thanks for your
quick response.

David A. Garbin 
Senior Fellow
Noblis
3150 Fairview Park Dr S
Falls Church, VA 22042
Phone:  +1 703.610.2050
Cell:     +1 703.795.6010
Email:   david.garbin at noblis.org

-----Original Message-----
From: grassuser-bounces at grass.itc.it
[mailto:grassuser-bounces at grass.itc.it] On Behalf Of Frank Warmerdam
Sent: Monday, August 06, 2007 4:00 PM
To: Spencer Fogg
Cc: grassuser at grass.itc.it
Subject: Re: [GRASS-user] "Random read is not supported by OGR for this
layer, cannot build support."

Spencer Fogg wrote:
> Hi, GRASS users! I am a novice, and have only been using this program 
> for a couple of months now. I'm having a problem using GRASS with 
> postgres for a project at work, and I was wondering if you guys could
help.
> 
>  
> 
> I'm working with shapefiles, and want to display them in GRASS. Some
of 
> these files are large enough to crash GRASS while cleaning, and even 
> more take longer to draw and redraw than I'd like. To avoid this, I'm 
> attempting to use v.external to connect to the files in a postGIS
table, 
> created using shp2pgsql. When I run v.external, however, I get a
strange 
> warning: "Random read is not supported by OGR for this layer, cannot 
> build support." Then when I try to display the created vector layer, 
> GRASS crashes.

Spencer,

On review of the OGR PostGIS driver I think this is a bug in the
driver's
"TestCapabilities" method.  Are you in a position to rebuild your GDAL
with
a patch?  I'd appreciate your filing a bug against GDAL/OGR for this
issue,
and we can pursue the discussion there.

   http://trac.osgeo.org/gdal/

Best regards,
-- 
---------------------------------------+--------------------------------
------
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 OSGeo,
http://osgeo.org

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