[postgis-users] PostGIS-PostgreSQL

[Doug_Newcomb at fws.gov]

I have a postgis dataset that is a series of fish collection trawls with
the  geometry fields for the endpoints and for the line between the
endpoints.  It seemed like the easiest way to do analysis on the endpoints
separately of the line the endpoints create at the time.  Two geometry
colums with differnt names and different indexes.  I'd do it differently
now, but it seemed to work well then.

Doug



Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
---------------------------------------------------------------------------------------------------------

The opinions I express are my own and are not representative of the
official policy of the U.S.Fish and Wildlife Service or Dept. of Interior.
Life is too short for undocumented, proprietary data formats.


                                                                           
             "Peter N.                                                     
             Schweitzer"                                                   
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             07/13/2009 11:17          Re: [postgis-users]                 
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Chris Hermansen wrote:
> I should have mentioned that it's not considered good practice to
> have more than one geometry column per table, and hence more than
> one geometry object per row. This makes sense if you think of rows
> as representational instances of real world objects.

Hmmm.  I'm storing two geometry columns, because in one I have the
geographic (unprojected) coordinates, and in the other the coordinates
in some projection.  This is to support several different map interfaces
some of which are projected, others not.  Since the points don't change
frequently, I can generate the projected coords once and then simply
use them rather than recalculate them on every web hit.  It's denormalized,
but seems sensible to me.  Would you disagree with this method?

Peter
--
Peter N. Schweitzer (MS 954, U.S. Geological Survey, Reston, VA 20192)
(703) 648-6533  FAX: (703) 648-6252  email: pschweitzer at usgs.gov
<http://geology.usgs.gov/peter/>
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