Re: [HACKERS] pg_upgrade to clusters with a different WAL segment size

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> On Tue, Nov 14, 2017 at 7:32 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> Even if that's the case, I fail to see why it'd be a good idea to have
>> any sort of pg_upgrade integration here. We should make pg_resetwal's
>> checks for this good enough, and not conflate something unrelated with
>> pg_upgrade goals.

> Both positions can be defended. Note that some users like to have the
> upgrade experience within one single command do as much as possible if
> possible, and this may include the possibility to switch segment size
> to make the tool more friendly. I definitely agree with your point to
> make the low-level magic happen in pg_resetwal though. Having
> pg_upgrade call that at will could be argued afterwards.

FWIW, I agree with Andres' position here. I think the charter of
pg_upgrade is to duplicate the old cluster as closely as it can,
not to modify its configuration. A close analogy is that it does not
attempt to upgrade extension versions while migrating the cluster.

regards, tom lane