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