Re: 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