[postgis-users] side location conflict in GeomUnion function

[Hisaji Ono]

Thank you very much, Paul.

 I've resolved this problem using "magical" Buffer function as follows.

select GeomUnion(Buffer(the_geom,0))  from kagawa group by  y2000;

 But island polygons were vanished, if these necessary, I should regenerate
these ones using Difference function.


> Have you checked that all your geometries are valid first?
>
> select * from geomtable where not isvalid(the_geom);
>
> invalid geometries are the #1 cause of topology failures.