Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

24.06.2024 01:59, Jelte Fennema-Nio wrote:
> On Sat, 22 Jun 2024 at 17:00, Alexander Lakhin <exclusion@gmail.com> wrote:
>> @@ -2775,6 +2775,7 @@
>>    SET LOCAL statement_timeout = '10ms';
>>    select count(*) from ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; -- this takes very long
>>    ERROR:  canceling statement due to statement timeout
>> +WARNING:  could not get result of cancel request due to timeout
>>    COMMIT;
> As you describe it, this problem occurs when the cancel request is
> processed by the foreign server, before the query is actually
> received. And postgres then (rightly) ignores the cancel request. I'm
> not sure if the existing test is easily changeable to fix this. The
> only thing that I can imagine works in practice is increasing the
> statement_timeout, e.g. to 100ms.

I'd just like to add that that one original query assumes several "remote"
queries (see the attached excerpt from postmaster.log with verbose logging
enabled).

Best regards,
Alexander