[postgis-users] PostGIS-PostgreSQL

[Paul Ramsey]

It's not the end of the world to have two geocolumns. From a practical
perspective, there will be a few apps that have a harder time making
sense of your tables, due to a one-spatial-column assumption. There's
not a bit storage implication to storing two points instead of one.

Note that, from a performance PoV, the cost of the re-projection is
really very small, so as an optimization it probably isn't a
world-beating thing. However, for things like measuring distances and
so on, the convenience of maintaining that projected column is
probably well worth it.

P.

On Mon, Jul 13, 2009 at 8:17 AM, Peter N.
Schweitzer<pschweitzer at usgs.gov> wrote:
> 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/>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>