Excerpts from Luca Ferrari's message of mar jul 06 02:53:03 -0400 2010:
> Hi,
> I don't see any direct link between the TupleDesc structure and the HeapTuple
> one, and it seems strange to me since to manipulate a tuple you often need the
> descriptor. What is the trick here?
You're supposed to know which relation you got the HeapTuple from, so
you get the TupleDesc from there.
