Fetching from psql procedures

Hi,

I'm looking for a way to build large xml documents based on a set of tables, hence using recursive queries.


something like:

  FOR rec1 IN ...
    FOR rec2 IN  ...

      RETURN QUERY select '<foo>
      FOR  rec3 IN  ...

        RETURN QUERY select (XMLELEMENT (...))::text

      END LOOP;
      RETURN QUERY select '</foo>

    END LOOP;
  END LOOP;



 but if I wrap this in a function, it seems that I won't get a result before the whole document is prepared.

 Is there any way to stream the result as it get produced ?
 or does anybody knows of a good tutotial for a task like this ?


 thanks and best regards,

 Marc Mamin