[postgis-users] ERROR: GEOS union() threw an error!

[strk at refractions.net]

On Tue, Oct 12, 2004 at 12:08:58PM -0600, Ethan Alpert wrote:
> 
> 
> Why does the following throw an error?

Run issimple() on them as the first thing when facing these problems.
If all input are simple try newer GEOS (if running GEOS-1.0.0).
--strk;

> 
> Error Msg:
> 
> spatialdb=> select geomunion(the_geom) from snaps where
> stripid='101001000351ED00';
> NOTICE:  TopologyException: no outgoing dirEdge found (127.169,38.0556)
> ERROR:  GEOS union() threw an error!
> 
> 
> Here's the Geometries:
> 
> spatialdb=> select catfrag, stripid,AsText(the_geom) from snaps where
> stripid='101001000351ED00';
> -[ RECORD 1
> ]-----------------------------------------------------------------------
> ------------------------------------------------------------------------
> ---------------------------
> catfrag | 101001000351ED013757480
> stripid | 101001000351ED00
> astext  | POLYGON((126.9405 38.2139166666667,127.171686111111
> 38.2092055555556,127.168805555556 38.0372638888889,126.941602777778
> 38.0439083333333,126.9405 38.2139166666667))
> -[ RECORD 2
> ]-----------------------------------------------------------------------
> ------------------------------------------------------------------------
> ---------------------------
> catfrag | 101001000351ED022377883
> stripid | 101001000351ED00
> astext  | POLYGON((126.941597222222 38.0758111111111,127.169166666667
> 38.0698111111111,127.16855 37.9064833333333,126.942888888889
> 37.9145527777778,126.941597222222 38.0758111111111))
> -[ RECORD 3
> ]-----------------------------------------------------------------------
> ------------------------------------------------------------------------
> ---------------------------
> catfrag | 101001000351ED023757478
> stripid | 101001000351ED00
> astext  | POLYGON((126.941597222222 38.0758111111111,127.169166666667
> 38.0698111111111,127.16855 37.9064833333333,126.942888888889
> 37.9145527777778,126.941597222222 38.0758111111111))
> 
> 
> Here's where it get's odd:
> 
> spatialdb=> select geomunion(the_geom) from snaps where
> catfrag='101001000351ED022377883' or catfrag='101001000351ED023757478'
> or catfrag='101001000351ED013757480';
> -[ RECORD 1
> ]-----------------------------------------------------------------------
> ------------------------------------------------------------------------
> ------------------------------------------------------------------------
> -----------------------------------------------------
> geomunion | SRID=4326;POLYGON((126.9405
> 38.2139166666667,127.171686111111 38.2092055555556,127.169113088743
> 38.0556206842087,127.16855 37.9064833333333,126.942888888889
> 37.9145527777778,126.941852819554 38.0439010209725,126.941602777778
> 38.0439083333333,126.9405 38.2139166666667))
> 
> 
> Why does this work when I manually query on the tables index? Note two
> of the geometries are the same. If I delete either the geomunion works.
> The geometries are all SRID=4326
> 
> I'm running postgres 7.4.3 and postgis 0.8.2
> 
> Time for an upgrade? Very odd behavior...IMHO
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