Re: Remove non-fast promotion Re: Should we remove a fallbackpromotion? take 2

At Tue, 21 Apr 2020 15:48:02 +0900, Fujii Masao <masao.fujii@oss.nttdata.com> wrote in 
> 
> 
> On 2020/04/21 15:36, Michael Paquier wrote:
> > On Tue, Apr 21, 2020 at 03:29:54PM +0900, Fujii Masao wrote:
> >> Yeah, but that's not documented. So I don't think that we need to keep
> >> the backward-compatibility for that.
> >>
> >> Also in that case, non-fast promotion is triggered. Since my patch
> >> tries to remove non-fast promotion, it's intentional to prevent them
> >> from doing that. But you think that we should not drop that because
> >> there are still some users for that?
> > It would be good to ask around to folks maintaining HA solutions about
> > that change at least, as there could be a point in still letting
> > promotion to happen in this case, but switch silently to the fast
> > path.
> 
> *If* there are some HA solutions doing that, IMO that they should be
> *changed
> so that the documented official way to trigger promotion (i.e., pg_ctl
> promote,
> pg_promote or trigger_file) is used instead.

The difference between fast and non-fast promotions is far trivial
than the difference between promotion happens or not.  I think
everyone cares about the new version actually promotes by the steps
they have been doing, but few of them even notices the difference
between the fast and non-fast.  If those who are using non-fast
promotion for a certain reason should notice the change of promotion
behavior in release notes.

This is similar to the change of the default waiting behvaior of
pg_ctl at PG10.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center