Clarify base backups and local pg_wal recycling

On Tue, 2026-09-29 at 21:03 +0530, Toppr Tenali wrote:

I would like to suggest a clarification to the PostgreSQL documentation regarding base
backups and local WAL recycling.

The documentation explains separately that:

- archived WAL required by a base backup can eventually be deleted once that backup
is safely archived

I'd say that is wrong - you need to *retain* the WAL required to recover a backup,
otherwise you cannot restore it. Where in the documentation do you see that sentence?

- WAL segments in pg_wal can be recycled or removed after they are no longer needed
and, when archiving is enabled, have been successfully archived.

Right, but you forgot that replication slots will also keep PostgreSQL from
deleting WAL segments.

However, I could not find an explicit statement about whether taking or completing a
base backup itself affects when WAL segments in the local pg_wal directory become
eligible for recycling/removal.

Could the documentation explicitly clarify this relationship?

I don't think that there is a relationship between WAL recycling and a base backup,
so there is nothing to document.

Yours,
Laurenz Albe

On Wednesday, September 30, 2026, Laurenz Albe <laurenz.albe@cybertec.at>
wrote:

On Tue, 2026-09-29 at 21:03 +0530, Toppr Tenali wrote:

However, I could not find an explicit statement about whether taking or

completing a

base backup itself affects when WAL segments in the local pg_wal

directory become

eligible for recycling/removal.

Could the documentation explicitly clarify this relationship?

I don't think that there is a relationship between WAL recycling and a
base backup,
so there is nothing to document.

In fact, the wording of -X fetch mode shows the non-linkage quite well.
Likewise -X stream also explains how pg_basebackup provides a behavior to
deal with the noninherent coordination between the two systems.

David J.