Re: BUG #17355: Server crashes on ExecReScanForeignScan in postgres_fdw when accessing foreign partition

Hello Etsura-san,
18.01.2022 11:01, Etsuro Fujita wrote:
> On Fri, Jan 7, 2022 at 3:19 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
>> On Thu, Jan 6, 2022 at 9:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
>>> 06.01.2022 12:56, Etsuro Fujita wrote:
>>>> I haven't tried to reproduce this yet
> I think a simple reproducer for this issue is:
>
> 1) Define the partitioned table async_pt as shown by Alexander.
> 2) Run concurrent transactions as follows.
>
> Session A: insert into async_pt values (3000);
> Session A: begin;
> Session A: update async_pt set a = a;
> Session B: delete from async_pt;
> Session A: commit;
>
> The commit in Session A would cause a server crash in Session B due to
> the segmentation fault.
>
> Also, I think a simple reproducer for the “cannot re-evaluate a
> Foreign Update or Delete during EvalPlanQual” error is:
>
> 1) Define the partitioned table async_pt as shown by Alexander.
> 2) Run concurrent transactions as follows.
>
> Session A: insert into async_pt values (3000);
> Session A: begin;
> Session A: update async_pt set a = a;
> Session B: update async_pt set a = a;
> Session A: commit;
>
> The commit in Session A would cause the transaction in Session B to
> abort with that error.
Thanks for the explanation and the fix!
I've made a simple isolation test (see attachment) to confirm this. And
it crashes without the fix as you said.
With your fix it works as expected (I was wondering how "plan->operation
!= CMD_SELECT" with RETURNING will work and I haven't seen any issues yet.)

(Besides that I've observed an infinite waiting for ShareLock with
step "s1i" { INSERT INTO pt VALUES (2000); }
This doesn't happen with a regular (not foreign) table.)

Best regards,
Alexander