Since Tim Hall of Oracle-Base fame posted several articles on 21c and why you shouldn’t use it (it’s not a long term supported version so better wait for 23c to be released), I asked a question about whether a non-CDB would still work with 21c – turns out it doesn’t, so with some spare time this week, I’ll be fiddling with it myself.
The reason I asked came out of my experience with a customer very recently for whom I migrated close to 60 databases from Exadata to ExadataCloud@Customer (Gen 2 based on X8M). Since they had no desire to touch container databases, nor do they encrypt anything, that led to some interesting findings.
C@C tooling will allow you to download 188.8.131.52 and 184.108.40.206 binaries with container database features that can be bypassed *if* you use a JSON file to create the database (last I checked, the web console does not allow that).
So what next? Well, we have a database (non-CDB). We then performed a DataGuard RMAN “duplicate for standby” and performed a switchover. For now, this database can act just as it did on the source Exadata, although it does now have a wallet and any new tablespaces will be created with transparent data encryption (non-encrypted new tablespaces are not supported).
Of course this is just kicking the problem into the future. When 23c is released and those 12.x databases get upgraded, CDBs will be a part of this landscape.
I’ll leave you with Tim’s thought on this…. basically, be prepared.