From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
---|---|
To: | David Steele <david(at)pgmasters(dot)net> |
Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, Stephen Frost <sfrost(at)snowman(dot)net>, Adrien NAYRAT <adrien(dot)nayrat(at)anayrat(dot)info>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Remove Deprecated Exclusive Backup Mode |
Date: | 2019-02-26 17:42:32 |
Message-ID: | CAHGQGwH8kEeRgrPkNg6De9uidJ72LinHfsbdiKp1Zso87W_Z+g@mail.gmail.com |
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On Tue, Feb 26, 2019 at 3:49 PM David Steele <david(at)pgmasters(dot)net> wrote:
>
> On 2/26/19 6:51 AM, Michael Paquier wrote:
> > On Mon, Feb 25, 2019 at 08:17:27PM +0200, David Steele wrote:
> >> Here's the really obvious bad thing: if users do not update their procedures
> >> and we ignore backup_label.pending on startup then they will end up with a
> >> corrupt database because it will not replay from the correct checkpoint. If
> >> we error on the presence of backup_label.pending then we are right back to
> >> where we started.
> >
> > Not really. If we error on backup_label.pending, we can make the
> > difference between a backend which has crashed in the middle of an
> > exclusive backup without replaying anything and a backend which is
> > started based on a base backup, so an operator can take some action to
> > see what's wrong with the server. If you issue an error, users can
> > also see that their custom backup script is wrong because they forgot
> > to rename the flag after taking a backup of the data folder(s).
>
> The operator still has a decision to make, manually, just as they do
> now. The wrong decision may mean a corrupt database.
Even in non-exclusive backup mode, the wrong decision may mean
a corrupt database. For example, what if the user may forget to save
the backup_label in the backup taken by using non-exclusive backup
method? So I'm not sure if this is the matter only for an exclusive backup.
Regards,
--
Fujii Masao
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