Re: when is RLS policy applied

I've looked for information on leakproofness of operators but haven't found
anything can you direct me to a source of this information?

On Fri, Jul 24, 2020 at 3:40 PM Ted Toth <txtoth(at)gmail(dot)com> wrote:

>
> On Fri, Jul 24, 2020 at 3:15 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>> Ted Toth <txtoth(at)gmail(dot)com> writes:
>> > I'm trying to understand when RLS select policy is applied so I created
>> the
>> > follow to test but I don't understand why the query filter order is
>> > different for the 2 queries can anyone explain?
>>
>> The core reason why not is that the ~~ operator isn't considered
>> leakproof. Plain text equality is leakproof, so it's safe to evaluate
>> ahead of the RLS filter --- and we'd rather do so because the plpgsql
>> function is assumed to be much more expensive than a built-in operator.
>>
>> (~~ isn't leakproof because it can throw errors that expose information
>> about the pattern argument.)
>>
>> regards, tom lane
>>
>
> Thanks for the explanation.
>
> Ted
>