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

Thank you for the kind words. We are having a great time!

Regarding the command knowing about the primary I think it is safe to assume. We can start this way and evolve in the future if needed. 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?

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