DROP TABLE IF EXISTS testtable;
CREATE TABLE testtable (key integer);

-- Note that there's no indexes, so updates have to do a seq scan.

CREATE OR REPLACE FUNCTION testfunc(data int, key1 int) RETURNS int AS $$
DECLARE
BEGIN
  FOR cnt IN 1..10000 LOOP
    UPDATE testtable SET key = data WHERE key = key1;
  END LOOP;
  RETURN 1;
END;
$$ LANGUAGE plpgsql;

INSERT INTO testtable VALUES (1);
BEGIN;
SELECT testfunc(1,1);
COMMIT;