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<[email protected]> 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: [email protected] > <http://geology.usgs.gov/peter/> > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
