Horton

Re: Remove Deprecated Exclusive Backup Mode

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: David Steele <david@pgmasters.net>, Laurenz Albe <laurenz.albe@cybertec.at>, Stephen Frost <sfrost@snowman.net>, Adrien NAYRAT <adrien.nayrat@anayrat.info>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-26T17:26:49Z
Lists: pgsql-hackers

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  1. Remove exclusive backup mode

On Tue, Feb 26, 2019 at 12:20 PM Fujii Masao <masao.fujii@gmail.com> wrote:
> So, let me clarify the situations;
>
> (1) If backup_label and recovery.signal exist, the recovery starts safely.
>        This is the normal case of recovery from the base backup.
>
> (2)If backup_label.pending and recovery.signal exist, as described above,
>        PANIC error happens at the start of recovery. This case can happen
>        if the operator forgets to rename backup_label.pending, i.e.,
>        operation mistake. So, after PANIC, the operator needs to fix her or
>        his mistake (i.e., rename backup_label.pending) and restart
>        the recovery.
>
> (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.

The if-conditions for 1 and 2 appear to be the same, which is confusing.

-- 
Robert Haas
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