On 28 January 2014 09:29, Tom McCallum <[email protected]> wrote: > Ok, really silly question now, how can a polygon field contain what looks > like multiple polygons. > > So I have a Shapefile of GB but its only got 3 polygons in, according to > PostGis, but there are lots of small island polygons as well which are not > attached to any of the main land masses, so I don't see how they can all be > one polygon? Can a polygon field have multiple polygons in without being a > multi-polygon?
It's probably a MultiPolygon. However, it is possible to have a regular Polygon of the ocean surrounding GB, with many internal rings for each island. See Well-known text [1] to get an idea of how these things are actually stored. Furthermore, you can query to see the geometry type using GeometryType [2]. If you have a MultiPolygon, you can split it into several regular polygons with ST_Dump. -Mike [1] https://en.wikipedia.org/wiki/Well-known_text [2] http://postgis.net/docs/GeometryType.html [3] http://postgis.net/docs/ST_Dump.html _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
