Re: walsummarizer can get stuck when switching timelines

On Thu, Jul 16, 2026 at 7:46 AM Thom Brown <thom(at)linux(dot)com> wrote:
> +# Cause the partial segment to get archived on the *new* timeline.
> +#
> +# In more detail: the WAL segment that contains the current insert
> LSN exists on
> +# timeline 1, but since all we did is CREATE TABLE dummy (), it
> wasn't full. We're
> +# now running on timeline 2, and pg_switch_wal() fills up the rest of
> the segment.
> +# So the full segment should get archived on timeline 2, but not on timeline 1.
> +# We do a CHECKPOINT here to make sure that the summarizer tries to progress.
> +$node2->safe_psql('postgres', <<EOM);
> +SELECT pg_switch_wal();
> +CHECKPOINT;
>
> Wouldn't we want the checkpoint's redo record to make it into the
> archived segment *before* switching wal?

I don't think so, but maybe you want to explain why you think so.

--
Robert Haas
EDB: http://www.enterprisedb.com