Downgrading Oracle Database to an Earlier Release

Hi all,

I was in a project where the customer had one database in a training environment to upgrade from 11g to 19c.

The customer requirement was to have a fallback option in case of any issue in the next few days.

The fallback option during the upgrade is to create a GUARANTEE RESTORE POINT. But after a few days, you can lose data in case you go back to the restore point.

To be honest, I have never seen a downgrade in all my Oracle life, but it was a customer requirement.

And yes, we are not touching the COMPATIBLE parameter after the upgrade :)

We did the upgrade to 19c using AutoUpgrade and everything works great.

But, when we decided to test the catdwgrd.sql, we had a lot of ora-600 at the end of the downgrade process.

Then, I found something that I was not aware of: A document called "Required Task to Preserve Downgrade Capability".

Where you have some patches to apply on 11g:

Required Task to Preserve Downgrade Capability

Downgrading Oracle Database to an Earlier Release

Also, make sure you are taking care of the Timezone, especially updating Timezone files in the 11g home.

Thanks

Alex