Thanks Mike,
 
  Yap that looks more like a union and was pretty fast, but then
couldn't figure out how to export it.
I right clicked on the layer - selected export data to shape.
 
Very strangely when I reopen the new shape file in ArcMap - it looks
unioned, but then when I open the same shape file in OpenJump - I can
still see the boundaries still and opening up the dbf there are clearly
274 records.  I even deleted the mxd, sbn, sbx files ArcMap created and
it still looked unioned when I reopened it in ArcMap and not unioned
when I look at it in open jump.
 
The union created in open jump is half the size of the ArcMap one too
and dbf is empty as I would expect since I didn't ask for any roll up of
attributes.
 
I'm very puzzled.  I have no idea why ArcMap shows this as unioned when
the size of the shape and the stats don't look that much different from
the original.  I'm sure I must be missing something here.
 
Stats looks like this is in open jump
 

Layer: OpenJumpUnion 

Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 1

        Min     Max     Avg     Total   
Pts     69795   69795   69795.0         69795   
Holes   0       0       0.0     0       
Components      219     219     219.0   219     
Area    1104.3917345465716      1104.3917345465716
1104.3917345465716      1104.3917345465716      
Length  733.4595414659133       733.4595414659133
733.4595414659133       733.4595414659133       
 
ArcMap Union
Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 274 
        Min     Max     Avg     Total   
Pts     5       45836   688.0   188644  
Holes   0       0       0.0     0       
Components      1       219     1.0     492     
Area    1.0783706500011592E-5   1104.373302353546
8.061118897843844       2208.7465780092134      
Length  0.013284095041776186    733.3902842391406
8.213194606088345       2250.4153220682065      
 
 
Original

Layer: st99_d00 

Envelope: Env[-179.14734 : 179.77850341796875, 17.884813 :
71.35256064399981]
# Features: 274

        Min     Max     Avg     Total   
Pts     5       45836   688.0   188644  
Holes   0       0       0.0     0       
Components      1       219     1.0     492     
Area    1.0783706500011592E-5   1104.373302353546
8.061118897843844       2208.7465780092134      
Length  0.013284095041776186    733.3902842391406
8.213194606088345       2250.4153220682065      

Signed,
Very confused Regina
________________________________

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Bresnahan, Mike
Sent: Monday, August 18, 2008 10:12 AM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] PostGIS 1.3.3 on Windows XP Unstable


> How the hell do you get it to do a real union?

Heh. Intuitive ArcMap is not. It took me forever to figure it out as
well. You can do a union a couple different ways. The way that seemed to
work the best for this is to:
 
1) Run ArcMap
2) Add the shapefile to your map
3) Open the edit toolbar.
4) Click on Start Editing.
5) Select the entire dataset by left clicking and then dragging a
rectangle around the geometry.
6) Select Union from the menu on the edit toolbar.
 
You should see the union happen right before your eyes.
 
I think I tried the Union Tool like you did and didn't get what I
expected. I think it just did a union on each individual feature instead
of doing an aggregate union.
 


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