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<p>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.<br>
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Doug<br>
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Doug Newcomb <br>
USFWS<br>
Raleigh, NC<br>
919-856-4520 ext. 14 doug_newcomb@fws.gov<br>
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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.<br>
<img width="16" height="16" src="cid:1__=0ABBFF61DFC9919A8f9e8a93df938690@fws.gov" border="0" alt="Inactive hide details for "Peter N. Schweitzer" <pschweitzer@usgs.gov>">"Peter N. Schweitzer" <pschweitzer@usgs.gov><br>
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<ul><b><font size="2">"Peter N. Schweitzer" <pschweitzer@usgs.gov></font></b><font size="2"> </font><br>
<font size="2">Sent by: postgis-users-bounces@postgis.refractions.net</font>
<p><font size="2">07/13/2009 11:17 AM</font>
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PostGIS Users Discussion <postgis-users@postgis.refractions.net></font></div></td></tr>
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<font size="2">chris.hermansen@timberline.ca, PostGIS Users Discussion <postgis-users@postgis.refractions.net></font></td></tr>
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<font size="2">Re: [postgis-users] PostGIS-PostgreSQL</font></td></tr>
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<tt>Chris Hermansen wrote:<br>
> I should have mentioned that it's not considered good practice to<br>
> have more than one geometry column per table, and hence more than<br>
> one geometry object per row. This makes sense if you think of rows<br>
> as representational instances of real world objects.<br>
<br>
Hmmm. I'm storing two geometry columns, because in one I have the<br>
geographic (unprojected) coordinates, and in the other the coordinates<br>
in some projection. This is to support several different map interfaces<br>
some of which are projected, others not. Since the points don't change<br>
frequently, I can generate the projected coords once and then simply<br>
use them rather than recalculate them on every web hit. It's denormalized,<br>
but seems sensible to me. Would you disagree with this method?<br>
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Peter<br>
-- <br>
Peter N. Schweitzer (MS 954, U.S. Geological Survey, Reston, VA 20192)<br>
(703) 648-6533 FAX: (703) 648-6252 email: pschweitzer@usgs.gov<br>
<</tt><tt><a href="http://geology.usgs.gov/peter/">http://geology.usgs.gov/peter/</a></tt><tt>><br>
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