[postgis-users] area calculation problem

[danny]

Hi, I have a problem.
I'm trying to calculate the area of a great number of sites on a specific
territory.
The problem is that these sites can overlap (as they do very frequently) and
I do not want to count the same portion of land twice.
A st_union would work with this right? Unfortunately my experience with this
function is that it is way too slow for the numerous polygons I would have
to merge. As a matter fact it would take years.
Does anybody know of a hack around this? (In PostGIS or ArcGIS)

Many thanks!
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