我有一个表accounts_balances，它由触发器独占管理：

create table accounts_balances (
    account_id integer primary key references accounts(id) on delete cascade,
    balance integer not null
);

create or replace function new_account() returns trigger as $$
begin
    insert into accounts_balances (account_id, balance) values (new.id, 0);
    return new;
end;
$$ language plpgsql;

create trigger new_account
after insert on accounts
for each row
execute procedure new_account();

create or replace function add_operation() returns trigger as $$
begin
    update accounts_balances
    set balance = balance + new.amount
    where account_id = new.creditor_id;
    update accounts_balances
    set balance = balance - new.amount
    where account_id = new.debitor_id;
    return new;
end;
$$ language plpgsql;

create trigger add_operation
after insert on operations
for each row
execute procedure add_operation();

-- etc ...

是否有方法添加策略以防止有人手动更新此表？
我试过：

alter table accounts_balances enable row level security;

drop policy if exists forbid_update on accounts_balances;
create policy forbid_update ON accounts_balances
for all
using (false);

但我还是可以这么做

update accounts_balances set balance = 0 where account_id = 10;