[postgis-users] Difference between Polygon and Multipolygon

[P Kishor]

On 2/19/07, Kai Behncke <kbehncke at igf.uni-osnabrueck.de> wrote:
> Dear list,
>
> could anybody please give me a practical example where it`s useful to use
> MULTIPOLYGON instead of POLYGON?
> I wonder where the difference is and I don`t know where it`s useful to use
> MULTIPOLYGON.
>


if you want to treat the islands of Hawaii as one entity.

more seriously, performance gains. You can take a dataset with
polygons, and coalesce them into a new dataset aggregated by some
common field value. If selecting by that common field value, querying
the new dataset will be much, much faster.

-- 
Puneet Kishor http://punkish.eidesis.org/
Nelson Inst. for Env. Studies, UW-Madison http://www.nelson.wisc.edu/
Open Source Geospatial Foundation http://www.osgeo.org/education/
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