Using PERFORM in plpgsql throws compile errors

Hi,

I am trying to create a really simple pl/pgsql based function to simply
return true or false depending on a query result ...

As I do not need the query result row, I want to use PERFORM to dump the
resulting data ... So, here's my attempt:

CREATE OR REPLACE FUNCTION islicensed(int8, int8) RETURNS bool AS '
DECLARE
pID ALIAS FOR $1;
aID ALIAS FOR $2;
BEGIN
PERFORM SELECT * FROM transactions x INNER JOIN tx_items i ON(x.id =
i.tx_id) where i.archive_id=aID and x.status=\'valid\' and x.person_id=pID;
RETURN FOUND;
END;
' LANGUAGE 'plpgsql';

However, even so the creation statement succeeds, any attempt to call
this function throws a compilation error:

ERROR: syntax error at or near "SELECT" at character 9
CONTEXT: PL/pgSQL function "islicensed" line 5 at perform

Why this? As I understand the docs, this is how it should work!?!

Any help is highly appreciated.

Oh, PostgreSQL 7.4.1 running on RH Linux ES 3.0 (not from RH rpm, but
compiled from sources) ...

Thanks,
Chris