Re: Add a hint to the "WAL summaries are required" errors

Hi Chao, Manu,

Thanks both , that's a good correction. I didn't realize the summarizer
backfills from the oldest WAL still on disk, so "summarization was not
enabled" isn't really the trigger; it's WAL being recycled before
summarization catches up. Dropping the conditional causes entirely also
sidesteps the wal_level=minimal case not fitting them, as Manu pointed out.

v2 attached, using Chao's wording:

HINT: Consider taking a new full backup to use as the basis for future
incremental backups.

Re-verified the summaries-removed path on master with the new wording.
Manu, thanks also for independently confirming it on wal_level=minimal and
that 007 still passes saves me chasing that path myself.

Regards,
Sai Pranav

On Thu, Oct 8, 2026 at 3:04 PM Manu <manuelreyesbravo(at)gmail(dot)com> wrote:

> Hi Sai,
>
> I tried the patch on master (v1 applies cleanly, and 007 still passes
> 3/3) and reproduced the error on several paths, including the
> wal_level=minimal case via 007. The hint shows up in all of them.
>
> > Would a shorter "Take a new full backup." be preferable?
>
> I think there is a case for it. On the minimal path the hint still
> fires, but its two causes do not really fit: summarize_wal is off there
> only because minimal requires it -- the actual reason is that the
> summarizer reaches that WAL and skips it on purpose (fast_forward) --
> and nothing was removed. And even in the main case the first cause is
> more a symptom than the condition: with the WAL still on disk, enabling
> summarize_wal after the full backup does not error, since the summarizer
> backfills from the oldest WAL present; it only fails once that WAL has
> been recycled before summarization caught up.
>
> So the remedy-only form you suggested reads correctly in all of them.
> If you would rather keep naming the minimal case, there is existing
> wording to mirror at xlog.c:6037:
>
> Use a backup taken after setting "wal_level" to higher than "minimal".
>
> Happy to share the repro script if it helps.
>
> Regards,
> Manu
>