[postgis-users] TopologyException with geomunion

[David Orme]

Hi all,

I've run into an exception when trying to union two multipolygons.  
The features are both simple and valid:

range_maps=# select isvalid(geom), issimple(geom) from viverrid_psar  
where node_number in (-3,-21);
isvalid | issimple
---------+----------
t       | t
t       | t
(2 rows)


but when I try and union these I get the following:

range_maps=# insert into viverrid_psar (taxon_name, node_number,  
subclades, branch_length,  n_tips, n_subclades, node_height,  
richness, geom)values ('',-2,'{-3,-21}',9.9,31,2,18.1,31,(select  
geomunion(geom) from viverrid_PSAR where node_number in (-3,-21)));
NOTICE:  TopologyException: Directed Edge visited twice during ring- 
building at  (1.13203e+07,402571)
ERROR:  GEOS union() threw an error!

I don't think I'm doing something dumb, but I thought I'd check  
before I start posting bug reports..

Cheers,
David