I did not test this scenario myself, but it should be possible.
Flashback is a good method to revert back.
Mike Dietrich swears by it:
https://mikedietrichde.com/2017/08/29/fallback-strategy-flashback-to-guaranteed-restore-points/
and Oracle's own 19c Autoupgrade tool creates a guaranteed restore point to
fall back.
Regarding log format changes - since 19c binaries are doing the flashback,
they should be able to understand both 11g and 19c log formats. And once
flashback is done and db restarted with resetlogs with 11g binaries, the
11g binaries will not need any logs generated by 19c.
Having to separately recreate or restore controlfile is never mentioned in
upgrade flashback scenarios. The standby should make no difference.
The only potential extra care may be with preserving spfile and password
file.
And making sure not to advance compatible during the upgrade ....
thanks,
Albert Balbekov
On Tue, Mar 23, 2021 at 12:54 PM Andrew Kerber <andrew.kerber@xxxxxxxxx>
wrote:
For reasons too numerous to list, it is necessary for us to do some
upgrade validation testing on our existing dataguard standby of
production. This is an upgrade from 11.2.0.4 to the latest 19c version.
These are the steps I can see as needed for the process of validation and
testing:
1. Install and patch the 19c software to the most recent version.
2. Create a guaranteed restore point on the standby database.
3. Open the standby database read-write.
3. Run DBUA to upgrade the snapshot standby to 19c.
4. Run testing as required
5. Shutdown standby
6. startup mount the standby from the 11g home and revert to the
guaranteed restore point.
7. Resume the redo apply on the standby.
Am I missing a step here? Will there be a problem with the control files
when I flash the database back to the restore point after an upgrade? I
would think there would not be a problem since oracle should be designed to
handle this, but I have tried an upgrade of a snapshot standby before,
though I have done other destructive testing of course.
--
Andrew W. Kerber
'If at first you dont succeed, dont take up skydiving.'
