Re: Prevent printing "next step instructions" in initdb and pg_upgrade - Mailing list pgsql-hackers

On Mon, Nov 2, 2020 at 2:23 PM Magnus Hagander <magnus@hagander.net> wrote:
>
> On Tue, Oct 27, 2020 at 12:40 PM Bruce Momjian <bruce@momjian.us> wrote:
> >
> > On Tue, Oct 27, 2020 at 12:35:56PM +0100, Peter Eisentraut wrote:
> > > On 2020-10-27 11:53, Bruce Momjian wrote:
> > > > On Tue, Oct 27, 2020 at 11:35:25AM +0100, Peter Eisentraut wrote:
> > > > > On 2020-10-06 12:26, Magnus Hagander wrote:
> > > > > > I went with the name --no-instructions to have the same name for both
> > > > > > initdb and pg_upgrade. The downside is that "no-instructions" also
> > > > > > causes the scripts not to be written in pg_upgrade, which arguably is a
> > > > > > different thing. We could go with "--no-instructions" and
> > > > > > "--no-scripts", but that would leave the parameters different. I also
> > > > > > considered "--no-next-step", but that one didn't quite have the right
> > > > > > ring to me. I'm happy for other suggestions on the parameter names.
> > > > >
> > > > > What scripts are left after we remove the analyze script, as discussed in a
> > > > > different thread?
> > > >
> > > > There is still delete_old_cluster.sh.
> > >
> > > Well, that one can trivially be replaced by a printed instruction, too.
> >
> > True. On my system is it simply:
> >
> >         rm -rf '/u/pgsql.old/data'
> >
> > The question is whether the user is going to record the vacuumdb and rm
> > instructions that display at the end of the pg_upgrade run, or do we
> > need to write it down for them in script files.
>
> That assumes for example that you've had no extra tablespaces defined
> in it. And it assumes your config files are actually in the same
> directory etc.
>
> Now, pg_upgrade *could* create a script that "actually works" for most
> things, since it connects to the system and could then enumerate
> things like tablespaces and config file locations, and generate a
> script that actually uses that information.
>
> But getting that to cover things like removing/disabling systemd
> services or init jobs or whatever the platform uses can quickly get
> pretty complex I think...
>
> I wonder if we should just not do it and just say "you should delete
> the old cluster". Then we can leave it up to platform integrations to
> enhance that, based on their platform knowledge (such as for example
> knowing if the platform runs systemd or not). That would leave us with
> both pg_upgrade and initdb printing instructions, and not scripts, and
> solve that part of the issue.
>
> Thinking further, there has been one other thing that we've talked
> about before, which is to have pg_upgrade either run extension
> upgrades, or generate a script that would run extension upgrades. If
> we want to do that as form of a script, then we're bringing the
> scripts back into play again... But maybe that's actually an argument
> for *not* having pg_upgrade generate that script, but instead either
> do the extension upgrades automatically, or have a separate tool that
> one can run independent of pg_upgrade...

PFA a rebased version of this patch on top of what has happened since,
and changing the pg_upgrade parameter to be --no-scripts.

-- 
 Magnus Hagander
 Me: https://www.hagander.net/
 Work: https://www.redpill-linpro.com/