| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Vitaly Davydov <v(dot)davydov(at)postgrespro(dot)ru> |
| Cc: | vignesh C <vignesh21(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alexander Lakhin <exclusion(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, "tomas(at)vondra(dot)me" <tomas(at)vondra(dot)me> |
| Subject: | Re: Slot's restart_lsn may point to removed WAL segment after hard restart unexpectedly |
| Date: | 2025-06-18 16:47:09 |
| Message-ID: | CAPpHfdv3UEUBjsLhB_CwJT0xX9LmN6U+__myYopq4KcgvCSbTg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Jun 18, 2025 at 6:50 PM Vitaly Davydov <v(dot)davydov(at)postgrespro(dot)ru> wrote:
> > I think, it is a good idea. Once we do not use the generated data, it is ok
> > just to generate WAL segments using the proposed function. I've tested this
> > function. The tests worked as expected with and without the fix. The attached
> > patch does the change.
>
> Sorry, forgot to attach the patch. It is created on the current master branch.
> It may conflict with your corrections. I hope, it could be useful.
Thank you. I've integrated this into a patch to improve these tests.
Regarding assertion failure, I've found that assert in
PhysicalConfirmReceivedLocation() conflicts with restart_lsn
previously set by ReplicationSlotReserveWal(). As I can see,
ReplicationSlotReserveWal() just picks fresh XLogCtl->RedoRecPtr lsn.
So, it doesn't seems there is a guarantee that restart_lsn never goes
backward. The commit in ReplicationSlotReserveWal() even states there
is a "chance that we have to retry". Thus, I propose to remove the
assertion introduced by ca307d5cec90.
Any objection from backpatching 0001 though 17 and pushing 0002 to the head?
------
Regards,
Alexander Korotkov
Supabase
| Attachment | Content-Type | Size |
|---|---|---|
| v4-0002-Remove-excess-assert-from-InvalidatePossiblyObsol.patch | application/octet-stream | 1.3 KB |
| v4-0001-Improve-runtime-and-output-of-tests-for-replicati.patch | application/octet-stream | 6.4 KB |
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