[postgis-users] Length of Bigint, Double and Text fields

[Chris Hermansen]

Peter;

The canonical description of DBase files seems to be

http://www.clicketyclick.dk/databases/xbase/format/

On Tue, 2009-12-01 at 17:28 +0100, Peter Hopfgartner wrote:
> Mark Cave-Ayland wrote:
> > Peter Hopfgartner wrote:
> >
> >> Dear PostGIS devels,
> >>
> >> since we right in the middle of comparing interoperability of shape 
> >> files between some FOSS programs and ArcGIS, we encoutered also the 
> >> following:
> >>
> >> gvSIG chokes on the Bigint as produced by pgsql2shp. Looking at 
> >> ArcGIs generated files, the max length for numbers is 19, compared to 
> >> 20 for integers and 32 for floating points as in pgsql2shp. This 
> >> seems to be confirmed by some Borland tools, when configured for 
> >> dBase III+.
> >>
> >> Another limit seems to be that of text fields, that must be no longer 
> >> then 254. This is the maximum as given by ArcGIS and by the Borland 
> >> tool.
> >>
> >> Another point is Boolean: ArcGIS seems to not allow the creation of 
> >> boolean fields and the Borland Tool ("Database Desktop") says that 
> >> Booleans have a length of 1.
> >>
> >> Regards,
> >>
> >> Peter
> >
> > Hi Peter,
> >
> > You've brought up some interesting points here. Can you actually 
> > clarify these changes with regard to parts of the official shapefile 
> > spec, or have they been found purely through experimentation?
> >
> >
> > ATB,
> >
> > Mark.
> >
> Hi Mark,
> 
> I do still have to figure out, if there are public specs for this. All 
> I've found is, that attributes should be in data base files which are in 
> dBase format 
> (http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf). From the 
> analysis of the file (and Wikipedia: 
> http://en.wikipedia.org/wiki/Shapefile), it seems that this should be 
> dBase III. I do not have any evidence that there is a public spec for 
> dBase III.
> So all we did is basically gather some experimental data, where ArcGIS 
> and gvSIG are our references. The first, because ESRI introduced the 
> shape file format and gvSIG, because it is the desktop environment that 
> we encourage our customers to use. Anyway, we have an old 
> Borland/Inprise tool ("Database Desktop") here for managing dBase files 
> and used it for our tests.
> 
> Peter
> 


-- 
Regards,

Chris Hermansen    ·    mailto:chris.hermansen at timberline.ca
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