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From: px shi <spxlyy123@gmail.com>
Date: Fri, 8 Aug 2025 13:50:19 +0800
Message-ID: <CAAccyYLYZmwQiNMoJcQgo5t+E24rDtu1ZeBUrER7ZTKNAcZesw@mail.gmail.com>
Subject: Re: Questions about the continuity of WAL archiving
To: Adrian Klaver <adrian.klaver@aklaver.com>
Cc: pgsql-general@lists.postgresql.org
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Thank you for your reply.
The archived files can be used for PITR (Point-In-Time Recovery), allowing
recovery to any point between WAL 80 and 100 on timeline 1.
Additionally, if there's a backup taken during timeline 1 and a switchover
to a new primary has occurred without taking a new full backup yet, these
WAL logs can still be used to recover to any point on timeline 2.

Regards,
Pixian Shi

Adrian Klaver <adrian.klaver@aklaver.com> =E4=BA=8E2025=E5=B9=B48=E6=9C=888=
=E6=97=A5=E5=91=A8=E4=BA=94 12:25=E5=86=99=E9=81=93=EF=BC=9A

> On 8/7/25 20:20, px shi wrote:
> > Hi,
> > There is a scenario: the current timeline of the PostgreSQL primary nod=
e
> > is 1, and the latest WAL file is 100. The standby node has also receive=
d
> > up to WAL file 100. However, the latest WAL file archived is only file
> > 80. If the primary node crashes at this point and the standby is
> > promoted to the new primary, archiving will resume from file 100 on
> > timeline 2. As a result, WAL files from 81 to 100 on timeline 1 will be
> > missing from the archive.
>
> What are you planning to do with the archived files?
>
> Also is not the case that once the primary crashes you are in a split
> brain case and can't really trust it's timeline anymore?
>
>
> > Is there a good solution to prevent this situation?
> >
> > Regards,
> > Pixian Shi
>
>
> --
> Adrian Klaver
> adrian.klaver@aklaver.com
>

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<div dir=3D"ltr">Thank you for your reply.=C2=A0<div>The archived files can=
 be used for PITR (Point-In-Time Recovery), allowing recovery to any point =
between WAL 80 and 100 on timeline 1.=C2=A0</div><div>Additionally, if ther=
e&#39;s a backup taken during timeline 1 and a switchover to a new primary =
has occurred without taking a new full backup yet, these WAL logs can still=
 be used to recover to any point on timeline 2.<br></div><div><br></div><di=
v>Regards,<br>Pixian Shi<br></div></div><br><div class=3D"gmail_quote gmail=
_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">Adrian Klaver &lt;<=
a href=3D"mailto:adrian.klaver@aklaver.com">adrian.klaver@aklaver.com</a>&g=
t; =E4=BA=8E2025=E5=B9=B48=E6=9C=888=E6=97=A5=E5=91=A8=E4=BA=94 12:25=E5=86=
=99=E9=81=93=EF=BC=9A<br></div><blockquote class=3D"gmail_quote" style=3D"m=
argin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;borde=
r-left-color:rgb(204,204,204);padding-left:1ex">On 8/7/25 20:20, px shi wro=
te:<br>
&gt; Hi,<br>
&gt; There is a scenario: the current timeline of the PostgreSQL primary no=
de <br>
&gt; is 1, and the latest WAL file is 100. The standby node has also receiv=
ed <br>
&gt; up to WAL file 100. However, the latest WAL file archived is only file=
 <br>
&gt; 80. If the primary node crashes at this point and the standby is <br>
&gt; promoted to the new primary, archiving will resume from file 100 on <b=
r>
&gt; timeline 2. As a result, WAL files from 81 to 100 on timeline 1 will b=
e <br>
&gt; missing from the archive.<br>
<br>
What are you planning to do with the archived files?<br>
<br>
Also is not the case that once the primary crashes you are in a split <br>
brain case and can&#39;t really trust it&#39;s timeline anymore?<br>
<br>
<br>
&gt; Is there a good solution to prevent this situation?<br>
&gt; <br>
&gt; Regards,<br>
&gt; Pixian Shi<br>
<br>
<br>
-- <br>
Adrian Klaver<br>
<a href=3D"mailto:adrian.klaver@aklaver.com" target=3D"_blank">adrian.klave=
r@aklaver.com</a><br>
</blockquote></div>

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