Oracle: Upgrade Methods

The different upgrade methods you can use to upgrade your database to the new Oracle Database 9i release or higher are: 

1) Database Upgrade Assistant (DBUA)
2) Manual Upgrade
3) Export/Import
4) Data Copying
5) Golden Gate

DBUA (Database Upgrade Assistant)

-   The DBUA automates the upgrade process by performing all of the tasks normally performed manually. 

-   The DBUA makes appropriate recommendations for configuration options such as tablespaces and redo logs.

-   This method is very easy and user friendly. But if any error occurs it will take time to diagnose the error as the upgrade process is done automatically by the upgrade assistant. 

Manual Upgrade

-   A manual upgrade consists of running SQL scripts and utilities from a command line to upgrade a database to the new Oracle Database release. 

-   A manual upgrade gives finer control over the upgrade process as it is done step by step manually. So if any error occurs, it is easier to diagnose the error. 

-   When manually upgrading a database, perform the following pre-upgrade steps:

• Analyze the database using the Pre-Upgrade Information Tool. The Upgrade Information Tool is a SQL script that ships with the new Oracle Database release, and must be run in the environment of the database being upgraded. 
• The Upgrade Information Tool displays warnings about possible upgrade issues with the database. It also displays information about required initialization parameters for the new Oracle Database release. 
• Prepare the new Oracle Home. 
• Perform a backup of the database.

Depending on the release of the database being upgraded, you may need to perform additional pre-upgrade steps (adjust the parameter file for the upgrade, remove obsolete initialization parameters and adjust initialization parameters that might cause upgrade problems). 


Note: 
-   DBUA can be used only if the source & target Oracle homes are on the same Server.
-   But manual upgrade will work even if the source and target Home are on different servers provided that the Hardware architecture and operating system on source and target Home are the same.


Example :
- You cannot manually upgrade a database from an AIX Operating System to Solaris Operating System.
- You cannot manually upgrade a database from a Solaris X86-64 Machine to Solaris SPARC 64-bit.




Export/Import:

-   The Export/Import upgrade method does not change the current database, which enables the database to remain available throughout the upgrade process. However, if a consistent snapshot of the database is required (for data integrity or other purposes), then the database must run in restricted mode or must otherwise be protected from changes during the export procedure. 

-   Most importantly, the Export/Import operation results in a completely new database. Although Export/Import creates an identical copy of the database, other factors, such as disk placement of data and unset tuning parameters, may cause unexpected performance problems. 

-   Upgrading an entire database by using Export/Import can take a long time, especially compared to using the DBUA or performing a manual upgrade. Therefore, you may need to schedule the upgrade during non-peak hours or make provisions for propagating to the new database any changes that are made to the current database during the upgrade. 

Data Copying:

-   You can copy data from one Oracle Database to another using database links. For example, you can create new tables and fill the tables with data by using the INSERT INTO statement and the CREATE TABLE ... AS statement. 

-   Copying data and Export/Import offer the same advantages for upgrading. Using either method, you can defragment data files and restructure the database by creating new tablespaces or modifying existing tables or tablespaces. In addition, you can copy only specified database objects or users. 

-   Copying data, however, unlike Export/Import, enables the selection of specific rows of tables to be placed into the new database. Copying data is a good method for copying only part of a database table. In contrast, using Export/Import, you can copy only entire tables 

GoldenGate:


-   Oracle GoldenGate is a comprehensive software package for enabling the replication of data in heterogeneous data environments.
-    The product set enables high availability solutions, real-time data integration, transactional change data capture, data replication, transformations, and verification between operational and analytical enterprise systems.

Source: Different Upgrade Methods For Upgrading Your Database [ID 419550.1]