On Thu, Jul 28, 2016 at 10:38 AM, Alex Ignatov <a.ignatov@postgrespro.ru> wrote:
> Sorry, what? You can rollback to previous version of software what you had.
>
> https://docs.oracle.com/cd/E11882_01/server.112/e23633/downgrade.htm#UPGRD007
Not so fast. This requires the db to be set in compatibility mode of
the lower version. Once that is removed, no downgrade is possible.
Also starting from Oracle 12 this downgrade option has been removed.
That is, you can't upgrade in-place from Or 11 to 12 and then
downgrade back. The only supported way is the restore from an old
backup (which is true for all products). I don't work in Oracle, but
got this clarified by someone who is an Oracle dba.