Bug#886742: [INFO] Bug#886742: postgresql-9.4-postgis-2.1 missing in stretch

[Francesco P. Lovergine]

On Tue, Jan 09, 2018 at 02:37:44PM +0100, Jürgen Fuchsberger wrote:
> >> What did you try, and what didn't work?
> > 
> > Probably pg_upgradecluster, and that is not supported for databases with
> > the postgis extension.
> > 
> Exactly. Just wanted to point out that upgrading was no possibility
> either, the actual problem was that the database could not be accessed
> or dumped after the upgrade.

While ideally one could use hook scripts to manage such kind of extensions
I would not try that approach in any case. A Postgis hard upgrade is 
generally a trial-and-error nightmare^Wexperience and it depends on
languages, extensions, encodings. Last time, I had to perform a series
of ad hoc setups before trying the restore. I strongly suggest to 
run both servers and extensions on the host in order to run a successfully shop 
upgrade later. 
That is definitively possible, I have at least one server still running 
both 8.4 and 9.4 with required Postgis extensions.

-- 
Francesco P. Lovergine