John Halleck wrote:
> On Fri, 6 Jul 2001, John Halleck wrote:
> > > [... Unique Record ID's ...]
> > > >http://rubens.its.unimelb.edu.au/~pgm/uisic/exchange/exchprop.html
> "nnnnn
> a numeric serial number, being an agreed fixed length for a given
> entity, and padded left with zeros. Unique within a given aa and
> bbb. See Entity List below for
> Making the number field a fixed size puts in assumptions about sizes.
> Why do this? (I.E. I don't see any advantage to this, and there are
> obvious problems with it, so I think I missed something.)
Some historical information may help here in understanding this. Peter
Matthews will be ablke to correct me here if I get anything wrong.
This system was developed more than 15 years ago by Peter Matthews and
others in the Informatics Commission of the UIS. It's implemented in the
system we have at present in Australia where we have had a National Karst
Index Database on computers of one form or another since 1985.
(its now on the web, see http://www.caves.org.au and click on Karst Database)
The exchprop doc gives for example: "AUVSA00035" being a cave tagged in
Australia by the Victorian Speleological Association as number 00035
That is stored in the database as the ID of a unique cave. Yes it's
limited to 100,000 caves (-1) but thats 100,000 caves for just that one
club VSA. Even say in the US with the National Speleological Society if
we imagine them using the UISIC system each gtotto there would have up
to 100,000 numbers to choose from so I don't think any club will find a
problemn with the numbers being limited.
The Memory in computers back in 1985 was quite pricy and limited and much
of the database design was done with limitations like that in mind.
Mike
-- -------------------------------------------------------------------- Michael Lake Active caver, Linux enthusiast and interested in anything technical. Safety Convenor, Australian Speleological Federation Owner, Speleonics (Australia) --------------------------------------------------------------------
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