It was a surprised to learn you have OCP credentials - your question comes out as unexpected in such context.

Project should be characterized as a migration rather than an upgrade - you do not upgrade when moving to a different Operating System, you migrate.

May we know how big your database is?

For a small to medium size database I would...

1- Export - either exp or expdp current database.
2- Pre Create new database.
3- Import - either imp or impdp

Plenty of documentation about this matter is in the net.