-- Running this snippet creates a function. This function can then be executed
-- in this manner:
--          SELECT truncate_tables('postgres');

CREATE OR REPLACE FUNCTION truncate_tables(_username text)
  RETURNS void AS
$func$
BEGIN
   RAISE NOTICE '%', 
   -- EXECUTE  -- dangerous, test before you execute!
  (SELECT 'TRUNCATE TABLE '
       || string_agg(quote_ident(schemaname) || '.' || quote_ident(tablename), ', ')
       || ' CASCADE'
   FROM   pg_tables
   WHERE  tableowner = _username
   AND    schemaname = 'public'
   );
END
$func$ LANGUAGE plpgsql;