[postgis-users] Merge function in PostGIS

[Bruce Rindahl]

I need a merge function in PostGIS.  What this means is if I have a
multipolygon and if any two parts share a common edge I need the union of
the two parts in one polygon.  For example if I have:
MULTIPOLYGON(((partA)),((partB)),((partC))) where partA and partC intersect
or share a common edge, the result will be:
MULTIPOLYGON(((Union of partA & partC)),((partB)))

  I know it can be done via the following:

Get the number of polygons via NumGeometries();
For each part (obtained via GeometryN()), loop through all the other parts
and check if NumGeometries(GeomUnion(partA,partB)) = 1.
If it does, replace partA with GeomUnion(partA,partB) and drop partB.
Continue until all the parts are checked.

Before I start on this - Has someone already done this?  Is there a better
way?
Thanks
Bruce Rindahl