memory free of constantly changed function

Hello Tom Lane, Tao Ma

I saw the post with title "question about the _SPI_save_plan() and
plan cache" discussing about memory free of dropped function.

I am using dynamically created function to imitate dynamic compound
statement in DB2.
I use function_factory(t1 text, t2 text, t3 text), pasted below, to
create dynamic function pg_temp.dyn_eval(), t1 is function name, t2 is
DECLARE part, t3 is BEGIN-END part. The t1 is fixed to
pg_temp.dyn_eval in client side.
Every time pg_temp.dyn_eval() is created, it is called only once.
On client side, a resident ODBC application connects to PostgreSQL,
working until system power off.
The application repeatedly "select function_factory(t1, t2, t3);" to
create pg_temp.dyn_eval(), "select pg_temp.dyn_eval();", and "drop
function pg_temp.dyn_eval();".
I observed the memory used by the server side PostgreSQL process
"postgres: postgres" increasing constantly, altough I confirmed that
pg_temp.dyn_eval() was dropped for sure. I think the increasing memory
is maybe caused by "SPI plan memory context", as you discussed.

Could you help to give some advice to free the memory as soon as
pg_temp.dyn_eval() is dropped.
I am using PostgreSQL 8.2.4.

Thank you.
ning

-----
CREATE FUNCTION function_factory(t1 TEXT, t2 TEXT, t3 TEXT)
RETURNS VOID AS $$
DECLARE
func_body TEXT;
func_cmd TEXT;
BEGIN
func_body := 'DECLARE ';
func_body := func_body || t2;

func_body := func_body || 'BEGIN ';
func_body := func_body || t3;
func_body := func_body || ' END;';

func_cmd :=
'CREATE OR REPLACE FUNCTION ' || t1 ||
'() RETURNS VOID AS '
|| quote_literal(func_body)
|| ' LANGUAGE plpgsql VOLATILE;' ;

EXECUTE func_cmd;
END;
$$ LANGUAGE plpgsql VOLATILE;