On 4/18/24 01:03, Robert Haas wrote:
On Tue, Apr 16, 2024 at 7:25 PM David Steele <da...@pgmasters.net> wrote:
But it will not go out of its way to perform checks that are unrelated
to its documented purpose. And I don't think it should, especially if
we have another tool that already does that.
I'm not averse to having some kind of statement in the documentation
along the lines of "Note that pg_combinebackup does not attempt to
verify that the individual backups are intact; for that, use
pg_verifybackup."
I think we should do this at a minimum.
Here is a patch to do that.
I think here:
+ <application>pg_basebackup</application> only attempts to verify
you mean:
+ <application>pg_combinebackup</application> only attempts to verify
Otherwise this looks good to me.
Especially given how pg_combinebackup works, backups are going to
undergo a lot of user manipulation (pushing to and pull from storage,
decompressing, untaring, etc.) and I think that means we should take
extra care.
We are in agreement on that point, if nothing else. I am terrified of
users having problems with pg_combinebackup and me not being able to
tell whether those problems are due to user error, Robert error, or
something else. I put a lot of effort into detecting dumb things that
I thought a user might do, and a lot of effort into debugging output
so that when things do go wrong anyway, we have a reasonable chance of
figuring out exactly where they went wrong. We do seem to have a
philosophical difference about what the scope of those checks ought to
be, and I don't really expect what I wrote above to convince you that
my position is correct, but perhaps it will convince you that I have a
thoughtful position, as opposed to just having done stuff at random.
Fair enough. I accept that your reasoning is not random, but I'm still
not very satisfied that the user needs to run a separate and rather
expensive process to do the verification when pg_combinebackup already
has the necessary information at hand. My guess is that most users will
elect to skip verification.
At least now they'll have the information they need to make an informed
choice.
Regards,
-David
