The Oracle Upgrading methods are categorized into two types: the regular Oracle Upgrade methods and the Oracle Upgrade alternatives. You are going to use the regular upgrade methods if you are upgrading with the same Operating System (OS) and you can afford the average 30–90 minutes downtime. If not, you are going to have to use the alternatives.
Using the Database Upgrade Assistant (DBUA) is a regular Oracle Upgrade method. It is the most recommended method, especially for patch and major release upgrades, because it is the simplest of all the methods. You can choose DBUA if the OS stays the same and you can afford the downtime. The average downtime for DBUA is 30–90 minutes. In addition, Automatic Storage Management or Real Application Clusters should be installed. Also, your present database should be at least version 220.127.116.11.
The use of DBUA would be a good choice if you prefer graphical user interface (GUI) over manual command-line interface. GUI demands less effort as compared to Manual Interface. Aside from that, DBUA performs automatic pre-upgrade checks.
Manual upgrading is also a regular Oracle Upgrade method. As a regular method, it requires an average downtime of 30-90 minutes and the same operating system. If you prefer manual command-line interface over GUI, then choose to upgrade manually. Also, you are going to use manual upgrading if you want to migrate from an old hardware platform to a new one provided that the OS is the same.
The regular upgrading methods have disadvantages. If an error occurs during the mid-upgrade of DBUA, you cannot re-run it. Manual upgrading requires more manual steps. Therefore, you may encounter errors because of your inaccurate typing. If you are going to upgrade manually, make sure that you are careful and keen to details.
Despite their advantages, there are certain situations in which the use of DBUA and manual upgrading is not applicable. This is when you can go for the Oracle Upgrade alternatives.
These alternatives are recommended if you are going to upgrade from a version older than 18.104.22.168. It is also recommended if you are moving from a particular OS platform to a different one. In this case, the 64-bit and 32-bit versions from the same OS are regarded as the same platform.
The Oracle Upgrade alternative methods include the SQL Apply or Data Guard, Oracle Golden Gate, Oracle Streams, Original exp/imp or Data Pump expdp/impdp, Transportable Database and Transportable Tablespaces. These are good choices if you are going to re-organize your schemas or database storage. In addition, you may choose an alternative method if you want a downtime of less than 30 minutes.
There are certain factors on determining what Oracle Upgrade method is appropriate for your needs. Some of these factors include your desired amount of downtime, migrating to a new hardware platform, the OS architecture, your preference between GUI and command-line, the required amount and complexity of manual intervention and the version you want to upgrade.