Upgrade Methods for Upgrading to Oracle Database 11g Release 2
- Database Upgrade Assistant (DBUA)
- Manual Upgrade
- Oracle Data Pump Export
- Standard Import / Original Export and Import
- Oracle Transportable Tablespaces
- Oracle Data Guard SQL Apply (Logical Standby)
Each method has its pros and cons, which are described in detail in the Oracle White paper 486336 (http://www.oracle.com/technetwork/database/upgrade/11gr2-upgrade-methods-wp-2011-486336.pdf).
For low and medium important Databases, the DBUA is a good option to consider using as the first choice. Data Pump is better than the old import / export because it is faster and it can be parallelized.
For critical Databases, Export / Import using Datapump is the safest and most conservative. A copy of the original DB will be exported and imported into a new oracle home.