|From:||David Steele <david(at)pgmasters(dot)net>|
|To:||Bruce Momjian <bruce(at)momjian(dot)us>|
|Cc:||Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, 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|
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On 3/5/19 12:36 AM, Bruce Momjian wrote:
> On Thu, Feb 28, 2019 at 05:08:24PM +0200, David Steele wrote:
>> On 2/28/19 4:44 PM, Fujii Masao wrote:
>>> On Wed, Feb 27, 2019 at 4:35 PM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)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.
>> It is problematic because we have a message encouraging users to delete
>> backup_label when in fact they should be creating recovery.signal.
> Should we issue a client NOTICE/WARNING message as part of
> pg_start_backup to indicate what to do if the server crashes before
I'm not in favor of this since it will just encourage users to change
their log level and possibly miss important notices/warnings.
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