Re: [v9.4] row level security

Alexander Korotkov <aekorotkov@gmail.com> writes:
> On Wed, Aug 28, 2013 at 4:17 PM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
>> It is out of scope for this feature. We usually calls this type of
>> information leakage "covert channel"; that is not avoidable in principle.

> I think there is another "covert channel" much more serious than
> constrains. You can gather information about hidden data by reading query
> plans.

I'm not convinced by this argument that covert channels are "out of
scope".  That would be a fine justification for, say, a thesis topic.
However, what we're talking about here is a real-world feature that will
be of no real-world use if it can't stand up against rather obvious attack
techniques.  I'm not interested in carrying the maintenance and runtime
overhead of a feature that's only of academic value.
        regards, tom lane