Re: Fix RLS checks for UPDATE/DELETE FOR PORTION OF leftover rows

> On Jun 30, 2026, at 16:00, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>
>
>
>> On Jun 30, 2026, at 15:51, Ayush Tiwari <ayushtiwari(dot)slg01(at)gmail(dot)com> wrote:
>>
>> Hi,
>>
>> On Tue, 30 Jun 2026 at 13:16, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>> Hi,
>>
>> While revisiting “[8e72d914c] Add UPDATE/DELETE FOR PORTION OF”, I found a new issue where inserting leftover rows may skip row-level security checks.
>>
>> Please see if it is the same as this: PostgreSQL: Enforce INSERT RLS checks for FOR PORTION OF leftovers?
>>
>> If yes, it is already present in the PG 19 open list.
>>
>> Regards,
>> Ayush
>
> Thanks for pointing that out. I didn’t notice that thread.
>
> Yes, that’s the same issue. I saw Paul wrote this there:
> ```
> Skipping the RLS checks to insert the leftovers seems like the correct
> behavior to me, since we are skipping the ACL checks (per the
> standard). Shouldn't it be consistent?
> I think the reason we skip the checks is that semantically, the
> leftovers aren't changing anything: they are preserving the history
> that is already there.
> ```
>
> That explains why the ACL checks are skipped as stated in the doc, but I don’t think the same reasoning should apply to RLS checks. As I explained in my patch email, for example, directly inserting [70,100) is blocked by policy t_ins, but a user can work around that by inserting [1,100) and then updating [30,70), which seems like a security hole.
>

I just noticed that I forgot the attached again.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/