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From: "Colin 't Hart" <colinthart@gmail.com>
Date: Wed, 10 Dec 2025 12:43:01 +0100
Message-ID: <CAMon-aTxU9dOJ2Z7F3PvAbNYRygNgfY-zxsGgK4k8iQFRZrEew@mail.gmail.com>
Subject: pgBackrest and newer timelines
To: PostgreSQL General <pgsql-general@lists.postgresql.org>
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Hi,

Before a migration we tested a database restore on the new server -- which
was configured to archive its WAL, and has archived WAL on a new timeline
to our central backup server. We tested this twice.

Now we have done the migration, which due to the size of the database we
achieved by detaching the disks from the old server and attaching them to
the new (this was the easiest way to achieve an OS upgrade from Ubuntu
20.04 to Debian 12). ((Yes we reindexed the text columns.))

So now our new server is still on the original timeline, but our backup
server contains WAL from two new timelines.

What should we do? Can we safely remove that WAL from the backup server?
How?

Thanks,

Colin

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<div dir=3D"ltr"><div>Hi,</div><div><br></div><div>Before a migration we te=
sted a database restore on the new server -- which was configured to archiv=
e its WAL, and has archived WAL on a new timeline to our central backup ser=
ver. We tested this twice.</div><div><br></div><div>Now we have done the mi=
gration, which due to the size of the database we achieved by detaching the=
 disks from the old server and attaching them to the new (this was the easi=
est way to achieve an OS upgrade from Ubuntu 20.04 to Debian 12). ((Yes we =
reindexed the text columns.))</div><div><br></div><div>So now our new serve=
r is still on the original timeline, but our backup server contains WAL fro=
m two new timelines.</div><div><br></div><div>What should we do? Can we saf=
ely remove that WAL=C2=A0from the backup server? How?</div><div><br></div><=
div>Thanks,</div><div><br></div><div>Colin</div></div>

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