Re: BUG #16497: old and new pg_controldata WAL segment sizes areinvalid or do not match

On Thu, Jun 18, 2020 at 11:16:50AM -0400, Tom Lane wrote:
> Jeff Janes <jeff.janes@gmail.com> writes:
> > Since wal-segsize is changeable with pg_resetwal since v11, and pg_upgrade
> > is already calling pg_resetwal, shouldn't pg_upgrade ideally just deal with
> > this situation automatically by allowing the upgrade to also change this
> > value, rather than forcing the user to make them match manually?
> 
> The issue is that this is an initdb parameter, and pg_upgrade expects you
> to have already initdb'd the destination cluster.  We could redefine that,
> perhaps, but it'd be a large change in how one uses pg_upgrade and would
> certainly break a lot of scripts.
> 
> I'm aware that we could use pg_resetwal to deal with this one specific
> initdb parameter, but I see no point in hacking around the problem for
> just one parameter.  The general principle remains that you need to
> initdb the target with the same settings you used for the source.

Yep, that's pretty much the issue.  :-)

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee