topic Re: Nil v null geometries. Which one does ArcMap create when only entering attribute in Data Management Questions

Nil v null geometries. Which one does ArcMap create when only entering attribute data

TimLangner — Wed, 02 May 2012 09:06:22 GMT

Hi there

I am currently working with some spatial data, where there are developments at a stage where I cannot plot them on the map but I still need to record their details in the attribute table. Currently I simply enter the attribute details and it creates a new row with 0 in the shape and length fields. Could anyone tell me if this new row contains a nil geometry or a null geometry?

I am using ArcMap 10.0.4 and ArcSDE 9.3.1, with the back end being Oracle 10g. I came across an interesting article which talked about null v nil geometries for ArcMap 8 through to 9.3.1 and Oracle.
http://support.esri.com/en/knowledgebase/techarticles/detail/32237

Kind regards

Tim

Re: Nil v null geometries. Which one does ArcMap create when only entering attribute

VinceAngelo — Wed, 02 May 2012 10:56:13 GMT

I'd expect it to be NULL, but the answer may depend on the version and geometry
storage format. You can determine this yourself easily enough by using 'sqlplus' to
SELECT the geometry column and see what it returns.

- V

Re: Nil v null geometries. Which one does ArcMap create when only entering attribute

TimLangner — Thu, 03 May 2012 08:46:10 GMT

Thank you for your reply

vangelo

I'm not 100% certain of the storage format off hand. Also I don't have access to SQLplus myself at the moment and I can't check in ArcGIS because geometry checks on the SDE are not allowed.

However I was able to do a dissolve geoprocess of the feature class and it said it successfully completed it. It may be that null geometries are allowed when running dissolve geoprocess. Thus it may not actually matter going forward that they are stored as null.

Kind regards

Re: Nil v null geometries. Which one does ArcMap create when only entering attribute

VinceAngelo — Thu, 03 May 2012 11:41:50 GMT

Well, it depends on the application of course, but from a processing standpoint (especially a dissolve),
there isn't much difference between a NULL column and a nil geometry (you wouldn't union either).

- V

Re: Nil v null geometries. Which one does ArcMap create when only entering attribute

JoeBorgione — Thu, 03 May 2012 15:12:42 GMT

Just an additional $00.02: I make it a practice of scanning my data for and then deleting null geometries through the attribute table; look for the feature size (area or length) value that tips you off.