Upgrade Oracle 11g to 12c Database

Environment:
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Oracle VM Box 4.2
Oracle Linux 6.2 64-bit
Oracle 11.2.0.3.0 Database
Oracle 12.1.0.1.0 Database


Two ways to upgrade Oracle Databsae

1. Database Upgrade Assistant (DBUA).
2. Manual

• The  utlu121s.sql script has been replaced with the preupgrd.sql script. The new Pre-Upgrade Information Tool provides fix-up scripts with the ability to fix and address any issues identified by the pre-upgrade check script

• The previous upgrade script catupgrd.sql has been replaced with the new catctl.pl Parallel Upgrade Utility script which provides the ability to run upgrade scripts in parallel taking advantage of spare CPU capacity which can potentially reduce upgrade times

• If Flashback database is enabled, DBUA creates a guaranteed restore point which can be used in case we have a  failure in the upgrade process. We can also restart DBUA to recover from any failures during the upgrade.

• We can now use an existing RMAN backup which DBUA is aware of in case we need to restore the database to the pre-12c upgrade state

• Oracle XML DB is now a mandatory component of the Oracle 12c database and is automatically installed as part of the upgrade process if not found

• If Database Control from earlier release exists, we need to drop the same before upgrading the database. We can do this via DBUA or reduce the upgrade downtime by performing this task in advance by copying a new script emremove.sql from the 12c Oracle Hone and running it against the 11g database.

$ ./dbua