On 10/13/23 10:40, David Steele wrote:
> On 10/12/23 19:15, Michael Paquier wrote:
>> On Thu, Oct 12, 2023 at 10:41:39AM -0400, David Steele wrote:
>>> After some more thought, I think we could massage the "pg_control in
>>> backup_label" method into something that could be back patched, with
>>> more
>>> advanced features (e.g. error on backup_label and pg_control both
>>> present on
>>> initial cluster start) saved for HEAD.
>>
>> I doubt that anything changed in this area would be in the
>> backpatchable zone, particularly as it would involve protocol changes
>> within the replication commands, so I'd recommend to focus on HEAD.
>
> I can't see why there would be any protocol changes, but perhaps I am
> missing something?
>
> One thing that does have to change, however, is the ordering of
> backup_label in the base tar file. Right now it is at the beginning but
> we need it to be at the end like pg_control is now.
Well, no protocol changes, but overall this does not seem like a
direction that would be even remotely back patch-able. See [1] for details.
For back branches that puts us back to committing some form of 0001 and
0003. I'm still worried about the performance implications of 0001 on a
standby when in backup mode, but I don't have any better ideas.
If we do commit 0001 and 0003 to the back branches I'd still like to
hold off on HEAD to see if we can do something better there.
Regards,
-David
[1]
https://www.postgresql.org/message-id/e05f20f9-6f91-9a70-efab-9a2ae472e65d%40pgmasters.net