Re: Proposal: recent access based routing for primary-replica setups

> I would actually suggest including down state instances in case pgpool
> isn’t aware yet. It can exclude them once it does.
> For these cases maybe -1 ?

I don't think pgpool will triger failover even if
replication_delay_source_cmd returns -1 for such instance because
pgpool already has its own method to detect instance down (i.e. health
check) and method to avoid false positive
(i.e. failover_require_consensus).

Still for such instaces replication_delay_source_cmd returns -1 maybe
useful if it's logged for admins.

So I am Okay with the idea.

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

> Nadav Shatz
> Tailor Brands | CTO
>
>
> On Mon, Sep 22, 2025 at 7:34 AM Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
>
>> > Thank you for the kind words. We are having a great time!
>>
>> Glad to hear that!
>>
>> > Regarding the command knowing about the primary I think it is safe to
>> assume.
>>
>> Okay.
>>
>> > We can start this way and evolve in the future if needed.
>>
>> Agreed.
>>
>> > I can include a note about it in the notes that the command will only
>> receive the secondary instances as arguments.
>> >
>> > Anything else that comes to mind?
>>
>> Sounds like a reasonable requirement. Also the command excludes any
>> instance which is in down state?
>>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS K.K.
>> English: http://www.sraoss.co.jp/index_en/
>> Japanese:http://www.sraoss.co.jp
>>
>> > Nadav Shatz
>> > CTO
>> >
>> >> On Sep 16, 2025, at 7:30 PM, Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
>> >>
>> >> 
>> >>>
>> >>> Hi Tatsuo,
>> >>>
>> >>> Sorry for the late reply - I'm traveling with my family at the moment
>> (in
>> >>> Japan actually)
>> >>
>> >> Excellent! Hope you and your family are spending great time in Japan.
>> >>
>> >>> and might be delayed in responding.
>> >>
>> >> No problem at all. I think you should focus on the travel at this
>> >> moment.
>> >>
>> >>> Re your points:
>> >>> 1 - we can, but I have to say that a user I tend to prefer
>> configuration
>> >>> values not have a "magic" value that does something different than the
>> >>> usual case like this would create. I'd stick with what we already have
>> >>> planned. happy to hear from others on the mailing list as well of
>> course.
>> >>
>> >> Makes sense. I withdraw my proposal.
>> >>
>> >>> 2 - I think we can have the primary always be the first or we can
>> >>> completely remove it since it might be redundant as it's always going
>> to be
>> >>> 0. what do you think?
>> >>
>> >> What I am not sure is, whether we can assume the command always knows
>> >> which host (or IP) is primary? If the answer is yes, then we could
>> >> omit the primary. What do you think?
>> >>
>> >>> 3 - I agree with you, next version (after we clear everything else)
>> will
>> >>> have only ip/hostname+port.
>> >>
>> >> Thank you for understanding.
>> >>
>> >>> Let me know your thoughts
>> >>>
>> >>> Thanks!
>> >>>
>> >>>> On Tue, Sep 9, 2025 at 9:42 AM Tatsuo Ishii <ishii(at)postgresql(dot)org>
>> wrote:
>> >>>>
>> >>>> Hi Nadav,
>> >>>>
>> >>>>> Hi Tatsuo,
>> >>>>>
>> >>>>> Please find attached the 3 patch files (implementation, tests, docs)
>> with
>> >>>>> the updates we discussed.
>> >>>>>
>> >>>>> What do you think?
>> >>>>
>> >>>> I haven't read the code details yet but I have a few questions.
>> >>>>
>> >>>> 1) Can we use only replication_delay_source_cmd and if it's value is
>> >>>> 'builtin', then we treat it as replication_delay_source = builtin?
>> >>>> Maybe this is matter of taste but I would like to know your
>> >>>> opinion.
>> >>>>
>> >>>> 2) replication_delay_source_cmd will be given an ordered list of
>> >>>> instance identifiers. But it seems there's no way for the command
>> >>>> which one is the primary instance. Is it okay for the command?
>> >>>>
>> >>>> 3) Why do you have 3 kind of instance identifiers (application name,
>> >>>> hostname (IP) + port and node id? I thought "hostname (IP) + port"
>> >>>> is sufficient.
>> >>>>
>> >>>> Comments?
>> >>>> --
>> >>>> Tatsuo Ishii
>> >>>> SRA OSS K.K.
>> >>>> English: http://www.sraoss.co.jp/index_en/
>> >>>> Japanese:http://www.sraoss.co.jp
>> >>>>
>> >>>
>> >>>
>> >>> --
>> >>> Nadav Shatz
>> >>> Tailor Brands | CTO
>> >
>> >
>>