Re: issue with synchronized_standby_slots

On Thu, Oct 23, 2025 at 9:08 PM Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>
> On Thu, Oct 23, 2025 at 8:28 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > +-- Parallel worker does not throw error during startup.
> > +SET min_parallel_table_scan_size TO 0;
> > +SET max_parallel_workers_per_gather TO 2;
> > +SET parallel_setup_cost TO 0;
> > +SET parallel_tuple_cost TO 0;
> > +CREATE TABLE t1(a int);
> > +INSERT INTO t1 VALUES(1), (2), (3), (4);
> > +SELECT count(*) FROM t1;
> >
> > Isn't it better to reset these parameters after the test?
>
> I think the intention of this test case is to verify that the issue seen
> in HEAD no longer occurs with the patch applied. So in HEAD this test
> procedure needs to be able to reproduce the problem with
> synchronized_standby_slots and parallel workers, but does it actually do?
> I'm afraid additional steps are needed.
>
> Also, I wonder if it's really worth doing this test after the fix,
> since it seems a special case.
>

Agreed. I also don't see the need.

>
> +-- Cannot set synchronized_standby_slots to a invalid slot name.
> +ALTER SYSTEM SET synchronized_standby_slots='invalid*';
>
> Typo: "a invalid" should be "an invalid"
>

We can keep this test as the results with and without patch will be
different for this case.

HEAD:
postgres=# ALTER SYSTEM SET synchronized_standby_slots='invalid*';
ERROR: invalid value for parameter "synchronized_standby_slots": "invalid*"
DETAIL: Replication slot "invalid*" does not exist.

Patch:
postgres=# ALTER SYSTEM SET synchronized_standby_slots='invalid*';
ERROR: invalid value for parameter "synchronized_standby_slots": "invalid*"
DETAIL: replication slot name "invalid*" contains invalid character
HINT: Replication slot names may only contain lower case letters,
numbers, and the underscore character.

--
With Regards,
Amit Kapila.