[postgis-users] Using ST_NumInteriorRings() on MULTIPOLYGON

[maplabs at light42.com]

> From: Lee Hachadoorian <Lee.Hachadoorian+L at gmail.com>
> Subject: [postgis-users] Using ST_NumInteriorRings() on MULTIPOLYGON
>
> According to the docs, ST_NumInteriorRings() is supposed to work on
> MULTIPOLYGONs:
>
> "This will work with both POLYGON and MULTIPOLYGON types but only looks at
> the first polygon. Return NULL if there is no polygon in the geometry." [1]
>
> But when I try it I am getting NULL. Using on a POLYGON returns expected
> result. 
>  

every county in census_2013 is type MULTIPOLYGON,
  ninterrings is NULL for me here, too.. 

SELECT
  gid, statefp, countyfp, countyns, geoid, name, namelsad,
  ST_NRings(geom) As Nrings,
  ST_NumInteriorRings(geom) As ninterrings,
  geometrytype(geom)
 FROM census_geo_13.tl_2013_us_county;

--
postgis_full_version |
POSTGIS="2.1.1dev r12052" GEOS="3.4.3dev-CAPI-1.8.2 r3958" PROJ="Rel. 
4.8.0, 6 March 2012" GDAL="GDAL 1.11dev, released 2013/04/13"

version              | PostgreSQL 9.2.4 on 
x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu/Linaro 
4.6.3-1ubuntu5) 4.6.3, 64-bit

--
Brian M Hamlin
OSGeo California Chapter
blog.light42.com