Re: [HACKERS] Creating backup history files for backups taken from standbys

On 3/1/18 11:07 PM, Michael Paquier wrote:
> On Fri, Mar 02, 2018 at 02:29:13AM +0900, Fujii Masao wrote:
>> + * write a backup history file with the same name.
>>
>> So more than one backup history files with the same name
>> but the diffferent content can be created and archived.
>> Isn't this problematic because the backup history file that
>> users want to use later might be overwritten unexpectedly?
>
> Yeah, that's the intention behind the patch. Would that actually happen
> in practice though? We would talk about two backups running
> simultaneously on a standby, which would overlap with each other to
> generate a file aimed only at being helpful for debugging purposes, and
> we provide no information now for backups taken from standbys. We could
> of course make that logic a bit smarter by checking if there is an
> extsing file with the same name and create a new file with a different
> name. But is that worth the complication? That's where I am not
> convinced, and that's the reason why this patch is doing things this
> way.

+1. Given that the history files are not used during restore and are
present primarily for debugging purposes, I can't see worrying too much
about this unlikely (if possible) race condition.

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