Re: Standby accepts recovery_target_timeline setting?

On 9/27/19 11:58 AM, Fujii Masao wrote:
> On Sat, Sep 28, 2019 at 12:14 AM David Steele <david(at)pgmasters(dot)net> wrote:
>>
>> I think, at the very least, the fact that targeted recovery proceeds in
>> the absence of recovery.signal represents a bug.
>
> Yes, recovery target settings are used even when neither backup_label
> nor recovery.signal exist, i.e., just a crash recovery, in v12. This is
> completely different behavior from prior versions.

I'm not able to reproduce this. I only see recovery settings being used
if backup_label, recovery.signal, or standby.signal is present.

Do you have an example?

> IMO, since v12 is RC1 now, it's not good idea to change the logic to new.
> So at least for v12, we basically should change the recovery logic so that
> it behaves in the same way as prior versions. That is,
>
> - Stop the recovery with an error if any recovery target is set in
> crash recovery

This seems reasonable. I tried adding a recovery.signal and
restore_command for crash recovery and I just got an error that it
couldn't find 00000002.history in the archive.

> - Use recovery target settings if set even when standby mode

Yes, this is weird, but it is present in current versions.

> - Do not enter an archive recovery mode if recovery.signal is missing

Agreed. Perhaps it's OK to use restore_command if a backup_label is
present, but we certainly should not be doing targeted recovery.

> If we want new behavior in recovery, we can change the logic for v13.

Agreed, but it's not at all clear to me how invasive these changes would be.

Regards,
--
-David
david(at)pgmasters(dot)net