[postgis-devel] I want boxes

Sandro Santilli strk at keybit.net
Tue Nov 8 09:15:16 PST 2011


I need to compute the geographical extent of a set of records.
But I do not have them all in a raw, so can't use the ST_Extent
aggregate. Rather I'll have to simulate the aggregate myself,
in pl/pgsql.

I don't want GEOS to be involved (why would it?).
So, what I'd be normally doing is.... have a BOX returned
for each row and merge consecutive BOXES into a state BOX.

As of PostGIS-2.0.0, what's the recommended way for doing this ?

Note that I'll want the final BOX to hold dimension informations.

This seems to be the closest to what I need:

  ST_Envelope(ST_Collect(A, B));

Is that the best practice ?

--strk; 

  ()   Free GIS & Flash consultant/developer
  /\   http://strk.keybit.net/services.html



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