| From: | Thom Brown <thom(at)linux(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Srinath Reddy Sadipiralla <srinath2133(at)gmail(dot)com>, x4mmm(at)yandex-team(dot)ru, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: walsummarizer can get stuck when switching timelines |
| Date: | 2026-07-16 13:46:57 |
| Message-ID: | CAA-aLv6vjnQd84+s7Pgc6LkOwAFDHq++SbQ2a8aa-vKk0sS-DA@mail.gmail.com |
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On Thu, 16 Jul 2026 at 14:45, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Thu, Jul 16, 2026 at 8:59 AM Thom Brown <thom(at)linux(dot)com> wrote:
> > Well if we run pg_switch_wal(), we're effectively closing the current
> > segment. CHECKPOINT then emits its WAL after the switch. If the
> > summarizer needs a CHECKPOINT_REDO record in the segment being
> > archived, it would already be too late.
>
> OK, I think this is where we're seeing things differently. The
> summarizer doesn't need a CHECKPOINT_REDO record in the segment being
> archived. Rather, we need a CHECKPOINT_REDO record somewhere after the
> WAL that we want summarized. In this case, the WAL we want summarized
> is generated by the pg_switch_wal() call.
Ah, gotcha. Sorry for the noise.
Thom
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