ERROR: permission denied for database control

Hi,

I've encountered a weird problem in PostgreSQL :

postgres=> create user test password 'test';

postgres=> grant select on pg_catalog.pg_database_size to test;

postgres=> grant execute on function pg_catalog.pg_database_size(name) to test;

--login as user test
postgres=> select current_user;
current_user
--------------
test
(1 row)

--query individual database size is fine
postgres=> select pg_database_size('postgres');
pg_database_size
------------------
25611884
(1 row)

--fails if try to get all db size in one sql
postgres=> SELECT current_date,pg_database_size(pg_database.datname) from pg_database;
ERROR: permission denied for database control

Thanks,
Suya