Re: Documentation to upgrade logical replication cluster

On Mon, Jan 8, 2024 at 12:52 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Thu, Jan 4, 2024 at 2:22 PM vignesh C <vignesh21@gmail.com> wrote:
> >
> > Hi,
> >
> > We have documentation on how to upgrade "publisher" and "subscriber"
> > at [1], but currently we do not have any documentation on how to
> > upgrade logical replication clusters.
> > Here is a patch to document how to upgrade different logical
> > replication clusters: a) Upgrade 2 node logical replication cluster b)
> > Upgrade cascaded logical replication cluster c) Upgrade 2 node
> > circular logical replication cluster.
> > Thoughts?
> >
> > [1] - https://www.postgresql.org/docs/devel/pgupgrade.html
>
> Thanks for this. It really helps developers a lot. In addition to the
> docs, why can't all of these steps be put into a perl/shell script or
> a C tool sitting in the src/bin directory?
>
> I prefer a postgres src/bin tool which takes publisher and subscriber
> connection strings as the inputs, talks to them and upgrades both
> publisher and subscriber. Of course, one can write such a tool outside
> of postgres in their own programming language, but the capability to
> upgrade postgres servers with logical replication is such an important
> task one would often require it. Therefore, an off-the-shelf tool not
> only avoids manual efforts but makes it effortless for the users,
> after all, if any of the steps isn't performed as stated in the docs
> the servers may end up in an inconsistent state.
>

This idea has merits but not sure if we just add a few tests that
users can refer to if they want or provide a utility as you described.
I would prefer a test or two for now and if there is a demand then we
can consider having such a utility. In either case, I feel it is
better discussed in a separate thread.

--
With Regards,
Amit Kapila.