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help / color / mirror / Atom feedFrom: Masahiko Sawada <[email protected]>
To: Amit Kapila <[email protected]>
Cc: Antonin Houska <[email protected]>
Cc: Hayato Kuroda (Fujitsu) <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Mihail Nikalayeu <[email protected]>
Cc: Srinath Reddy Sadipiralla <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Robert Treat <[email protected]>
Subject: Re: Adding REPACK [concurrently]
Date: Fri, 8 May 2026 16:22:04 -0700
Message-ID: <CAD21AoAAyERNCFaG20ExXNquWkv3GELJ3CuYQnKc13uhSsnfYA@mail.gmail.com> (raw)
In-Reply-To: <CAA4eK1KWDbBk4FgbbWdivQLrPPzR4zgvfnHK4WjWC78rbuRVbg@mail.gmail.com>
References: <CADzfLwWFr9h_+cbSQvPpdxgLbVL5wwxFRx21ezNvLYgJM=FVCQ@mail.gmail.com>
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On Tue, Apr 7, 2026 at 8:49 PM Amit Kapila <[email protected]> wrote:
>
> On Tue, Apr 7, 2026 at 7:49 PM Antonin Houska <[email protected]> wrote:
> >
> > Hayato Kuroda (Fujitsu) <[email protected]> wrote:
> >
> > > 02. SnapBuildProcessRunningXacts
> > >
> > > Per my understanding, the db_specic snapshot can be also serialized. Is it
> > > possibility tha normal logical decoding system restores the snapshot and obtain
> > > the wrong result?
> >
> > I don't think that the database-specific xl_running_xacts WAL record affects
> > what SnapBuildSerialize() writes to disk: the contents of builder->committed,
> > etc. is updated by decoding COMMIT and ABORT records.
> >
>
> I think the point is that the other process say a walsender could
> restore such a snapshot making it take the wrong decision.
>
Right. I think it affects even concurrent REPACK (CONCURRENTLY)
running on other databases. They could end up restoring the snapshot
serialized by another REPACK command running on another database and
becoming the consistent state without waiting for transactions
concurrently running on the same database, which is clearly wrong.
Regards,
--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com
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Subject: Re: Adding REPACK [concurrently]
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