On 11/20/23 19:58, Andres Freund wrote:
On 2023-11-21 08:52:08 +0900, Michael Paquier wrote:
On Mon, Nov 20, 2023 at 12:37:46PM -0800, Andres Freund wrote:
Given that, I wonder if what we should do is to just add a new field to
pg_control that says "error out if backup_label does not exist", that we set
when creating a streaming base backup
That would mean that one still needs to take an extra step to update a
control file with this byte set, which is something you had a concern
with in terms of compatibility when it comes to external backup
solutions because more steps are necessary to take a backup, no?
I was thinking we'd just set it in the pg_basebackup style path, and we'd
error out if it's set and backup_label is present. But we'd still use
backup_label without the pg_control flag set.
So it'd just provide a cross-check that backup_label was not removed for
pg_basebackup style backup, but wouldn't do anything for external backups. But
imo the proposal to just us pg_control doesn't actually do anything for
external backups either - which is why I think my proposal would achieve as
much, for a much lower price.
I'm not sure why you think the patch under discussion doesn't do
anything for external backups. It provides the same benefits to both
pg_basebackup and external backups, i.e. they both receive the updated
version of pg_control.
I really dislike the idea of pg_basebackup having a special mechanism
for making recovery safer that is not generally available to external
backup software. It might be easy enough for some (e.g. pgBackRest) to
manipulate pg_control but would be out of reach for most.
Regards,
-David
