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From: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>
Date: Thu, 26 Feb 2026 02:38:44 -0800
Message-ID: <CAHg+QDeH0_qPFoPX=ybGJxG9mGcEodz+fsWg7EnRUi=SOCGGHg@mail.gmail.com>
Subject: Re: synchronized_standby_slots behavior inconsistent with
 quorum-based synchronous replication
To: Alexander Kukushkin <cyberdemn@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, 
	Amit Kapila <amit.kapila16@gmail.com>, 
	PostgreSQL-development <pgsql-hackers@postgresql.org>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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Hi Alexnader,

On Thu, Feb 26, 2026 at 1:29=E2=80=AFAM Alexander Kukushkin <cyberdemn@gmai=
l.com>
wrote:

> Hi,
>
> On Thu, 26 Feb 2026 at 09:45, shveta malik <shveta.malik@gmail.com> wrote=
:
>
>>
>> As suggested in [1], IMO, it is a reasonably good idea for
>> 'synchronized_standby_slots' to DEFAULT to the value of
>> 'synchronous_standby_names'. That way, even if the user missed to
>> configure 'synchronized_standby_slots' explicitly, we would still have
>> reasonable protection in place.
>
>
> Hmm.
> synchronous_standby_names contains application_names,
> while synchronized_standby_slots contains names of physical replication
> slots.
> These are two different things, and in fact sync replication doesn't even
> require to use replication slots.
> What is worse, even when all standbys use physical replication slots ther=
e
> is no guarantee that values in synchronous_standby_names will match
> physical slot names
>

That's right, thanks for reminding me. I am convinced that we can't use the
defaults of synchronous_standby_names for synchronized_standby_slots. What
do you think about the rest of the proposal?

Thanks,
Satya

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<div dir=3D"ltr"><div dir=3D"ltr">Hi Alexnader,</div><br><div class=3D"gmai=
l_quote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Thu=
, Feb 26, 2026 at 1:29=E2=80=AFAM Alexander Kukushkin &lt;<a href=3D"mailto=
:cyberdemn@gmail.com">cyberdemn@gmail.com</a>&gt; wrote:<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><div>Hi,</div><br=
><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Thu, 2=
6 Feb 2026 at 09:45, shveta malik &lt;<a href=3D"mailto:shveta.malik@gmail.=
com" target=3D"_blank">shveta.malik@gmail.com</a>&gt; wrote:<br></div><bloc=
kquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:=
1px solid rgb(204,204,204);padding-left:1ex"><br>
As suggested in [1], IMO, it is a reasonably good idea for<br>
&#39;synchronized_standby_slots&#39; to DEFAULT to the value of<br>
&#39;synchronous_standby_names&#39;. That way, even if the user missed to<b=
r>
configure &#39;synchronized_standby_slots&#39; explicitly, we would still h=
ave<br>
reasonable protection in place.</blockquote><div><br></div><div><div class=
=3D"gmail_quote">Hmm.</div><div class=3D"gmail_quote">synchronous_standby_n=
ames
 contains application_names, while=C2=A0synchronized_standby_slots contains=
=20
names of physical replication slots.</div><div class=3D"gmail_quote">These =
are two different things, and in fact sync replication doesn&#39;t even req=
uire to use replication slots.</div><div class=3D"gmail_quote">What is wors=
e, even when all standbys use physical replication slots there is no guaran=
tee that values in=C2=A0synchronous_standby_names will match physical slot =
names</div></div></div></div></blockquote><div><br></div><div>That&#39;s ri=
ght, thanks for reminding me. I am convinced that we can&#39;t use the defa=
ults of synchronous_standby_names for synchronized_standby_slots. What do y=
ou think about the rest of the proposal?</div><div><br></div><div>Thanks,</=
div><div>Satya</div></div></div>

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