Re: Remove Deprecated Exclusive Backup Mode

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>

To: Laurenz Albe <laurenz.albe@cybertec.at>

Cc: David Steele <david@pgmasters.net>, Stephen Frost <sfrost@snowman.net>, Adrien NAYRAT <adrien.nayrat@anayrat.info>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2019-02-28T14:44:06Z

Lists: pgsql-hackers

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Remove exclusive backup mode
- 39969e2a1e4d 15.0 landed

On Wed, Feb 27, 2019 at 4:35 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> Fujii Masao wrote:
> > So, let me clarify the situations;
> >
> > (3) If backup_label.pending exists but recovery.signal doesn't, the server
> >        ignores (or removes) backup_label.pending and do the recovery
> >        starting the pg_control's REDO location. This case can happen if
> >        the server crashes while an exclusive backup is in progress.
> >        So crash-in-the-middle-of-backup doesn't prevent the recovery from
> >        starting in this idea
>
> That's where I see the problem with your idea.
>
> It is fairly easy for someone to restore a backup and then just start
> the server without first creating "recovery.signal", and that would
> lead to data corruption.

Isn't this case problematic even when a backup was taken by pg_basebackup?
Because of lack of recovery.signal, no archived WAL files are replayed and
the database may not reach to the latest point.

Regards,

-- 
Fujii Masao