[postgis-users] Basic question #1 Managing temporality in spatial data - MAUP over time

Ben Madin ben at remoteinformation.com.au
Wed Feb 18 16:24:02 PST 2009

G'day all,

I hope no one minds this, but I have to deal with some changes to my  
data, and thought it might be a good opportunity to ask the basic  
questions I've been dwelling on for some time.

Having just received a new set of the spatial data I am working with  
(shapefiles of administrative regions), I am unsurprised to find that  
about 15 districts have gone (been amalgamated), some new ones  
appeared, and indeed one entire province removed!

My intention was to add two columns to my gis data table -  
geom_start_validity & geom_end_validity, and revise my queries (which  
normally are analysing / displaying movement information) to choose  
the appropriate geometry depending on the date range of the query.

Is the approach sound? (Is this a reasonable idea? Am I completely off  
track here? Will this make my table difficult to index? Should I find  
all the polygons which are the same and delete the duplicates,  
extending the validity dates?)

(The interface which relates to the entry of movements would also be  
amended to deliver a different set of provinces and districts  
depending on the date of the movements. How I deal with movements that  
occur over the transition is beyond me so far!)




Ben Madin

t : +61 8 9192 5455
f : +61 8 9192 5535
m : 0448 887 220
Broome   WA   6725

ben at remoteinformation.com.au

							Out here, it pays to know...

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