A plan for upgrading postgres?

[Christopher Allan Webber]

Heya everyone,

I'm not sure anyone else is seriously running postgresql right now, but
I've been using it for some test development, and eventually I intend to
deploy to GNU Guix machines.

I think to do this, we'll need to keep around the prior version of
postgres.  pg_upgrade requires it:

  https://www.postgresql.org/docs/9.4/static/pgupgrade.html

I think the right approach will be to keep around the prior version,
eg postgresql-9.4, as a first step.  As a second step, it might be nice
to have a package that's something like "postgres-upgrade-recent" which
has all the shorthands for pointing at both the prior postgres binary
and this one, and so hands the user a single script for running the
upgrade.

Just thought I'd write this out while thinking about it.  Does it make
sense?

 - Chris