Re: Recovery of .partial WAL segments

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From: Stefan Fercot <[email protected]>
To: [email protected] <[email protected]>
Subject: Re: Recovery of .partial WAL segments
Date: Fri, 2 Aug 2024 08:47:02 +0200
Message-ID: <CAPzjO7U4oM8pkLOPrMq=ugWHqjfo-a1hdm6rd2Y+y+Xqt_Tkdw@mail.gmail.com> (raw)
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Hi,

I've added a CF entry for this patch:
https://commitfest.postgresql.org/49/5148/

Not sure why CFbot CI fails on macOS/Windows while it works with the Github
CI on my fork (
https://cirrus-ci.com/github/pgstef/postgres/partial-walseg-recovery).

Many thanks in advance for your feedback and thoughts about this patch,
Kind Regards,
--
Stefan FERCOT
Data Egret (https://dataegret.com)

On Thu, Aug 1, 2024 at 10:23 PM Stefan Fercot <[email protected]>
wrote:

> Dear hackers,
>
> Generating a ".partial" WAL segment is pretty common nowadays (using
> pg_receivewal or during standby promotion).
> However, we currently don't do anything with it unless the user manually
> removes that ".partial" extension.
>
> The 028_pitr_timelines tests are highlighting that fact: with test data
> being being in 000000020000000000000003 and
> 000000010000000000000003.partial, a recovery following the latest timeline
> (2) will succeed but fail if we follow the current timeline (1).
>
> By simply trying to fetch the ".partial" file in XLogFileRead, we can
> easily recover more data and also cover that (current timeline) recovery
> case.
>
> So, this proposed patch makes XLogFileRead try to restore ".partial" WAL
> archives and adds a test to 028_pitr_timelines using current
> recovery_target_timeline.
>
> As far as I've seen, the current pg_receivewal tests only seem to cover
> the archives generation but not actually trying to recover using it. I
> wasn't sure it was interesting to add such tests right now, so I didn't
> considered it for this patch.
>
> Many thanks in advance for your feedback and thoughts about this,
> Kind Regards,
> --
> Stefan FERCOT
> Data Egret (https://dataegret.com)

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