Thread: We have a requirement to downgrade from PostgreSQL 9.5.4 to 9.5.2

On 09/19/2016 09:43 PM, Andreas Kretschmer wrote:
> It is binary compatible, so yes. But trust me, there is problem with the
> new version.

Just to be clear did you mean:

"But trust me, there is problem with the new version."

Or

But trust me, there is no problem with the new version.

>
> On 20 September 2016 06:00:59 CEST, KGA Official
> <kga.official@gmail.com> wrote:
>
>     Hi All,
>
>     We are currently running at 9.5.2 and plan to upgrade to 9.5.4, but
>     our change requirement needs to plan for a downgrade with data
>     preservation, before upgrade is authorized.
>
>     Thus, I am asking this: Is it safe to downgrade from 9.5.4 to 9.5.2
>     by simply replacing the binaries? We will keep the data folder same.
>
>     Thx!
>
>
> --
> Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail
> gesendet.


--
Adrian Klaver
adrian.klaver@aklaver.com

On Tue, Sep 20, 2016 at 3:21 PM, KGA Official <kga.official@gmail.com> wrote:
> Regarding "are you really going to downgrade again"?
> The upgraded postgres will be bundled along with product code changes and
> other products. So, if someone finds product issues, they will roll back
> everything together.
> So, essentially, yes. One requirement of the roll out is that it be possible
> to roll-back.

Roll-out can be a complicated requirement knowing that sometimes minor
releases can introduce new GUC parameters and those can generate WAL
records. Though it is a rare fact, it is not impossible, and things
are kept compatible as much as possible. Personally I find deploying a
backup of PGDATA instead of reusing an existing PGDATA with older
binaries after it has run with newer binaries a more iron-solid
approach, and I've learnt to be careful with such things..
--
Michael