RE: [postgis-users] An I/O error occured while sending to the backend

[Stefan Zweig]

hi mark,

thanks for your advice. it was a good idea to test whether only some of the geometrys cause the error. that is in fact the case. i have found out that some of the multipolygons of the the_geom are corrupt, so they are not really multipolygon.

is it possbile to catch this exception (p)sql-side within the query instead of crashing the whole database connection.

btw.: my postgis_version(): 1.2.1
my posgre: 8.1.4

kind regards, 

stefan


> -----Ursprüngliche Nachricht-----
> Von: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
> Gesendet: 15.08.07 23:49:42
> An: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
> Betreff: RE: [postgis-users] An I/O error occured while sending to the backend


> 
> On Wed, 2007-08-15 at 15:45 +0200, Stefan Zweig wrote:
> > hi mark, hi list,
> > 
> > i have a problem with running these querys:
> >  
> >  SELECT
> >  AddGeometryColumn('public','_g2994','the_geom_1','4326','MULTIPOLYGON',2);
> >  ALTER TABLE _g2994 DROP CONSTRAINT enforce_geotype_the_geom_1;
> >  ALTER TABLE _g2994 ADD CONSTRAINT enforce_geotype_the_geom_1 CHECK
> >  (geometrytype(the_geom_1) = 'MULTIPOLYGON'::text OR geometrytype(the_geom_1)
> >  = 'POLYGON'::text OR the_geom_1 IS NULL);
> >  
> >  everthing is alright up to here...
> >  
> >  then i run
> >  UPDATE _g2994 SET the_geom_1 = buffer(simplify(the_geom,0.0063775005),0)
> >  WHERE true
> > 
> > unfortunately i am not an expert in reading postgres' server.log but this what happens after the above querys where executed:
> 
> 
> Hi Stefan,
> 
> Which platform are you using - what is the output of "SELECT version()"
> and "SELECT postgis_full_version()"? If you Google for PostgreSQL/Signal
> 11 then it can be caused by bad hardware, a process exceeding its ulimit
> threshold or a bug in the backend (perhaps GEOS/PostGIS).
> 
> In some cases, the problem can be caused by a single geometry within a
> table - perhaps the buffer() and/or simplify() calculations are causing
> in error? In this case you could try and identify the geometry in
> question doing something like:
> 
> CREATE TABLE test AS SELECT gid,
> buffer(simplify(the_geom,0.0063775005),0) FROM _g2994;
> 
> If this crashes, then the first geometry that isn't in the test table is
> causing it to crash, i.e. the geometry with the next highest gid.
> 
> 
> HTH,
> 
> Mark.
> 
> -- 
> ILande - Open Source Consultancy
> http://www.ilande.co.uk
> 
> 
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