The tables
are created in the Oracle 11g database based on queries of data from a separate source database.
This method allows you to bring over data incrementally and to limit the rows and columns
migrated. However, you will need to be careful that the copied data maintains all the necessary
relationships among tables as well as any indexes or constraints. As with the Export/Import method,
this method may require a significant amount of time for large databases.
NOTE
If you are changing the operating platform at the same time, you can
use transportable tablespaces to move the data from the old database
to the new database. For very large databases, this method may be
faster than the other data-copying methods. See Chapter 17 for the
details on transportable tablespaces.
Selecting the proper upgrade method requires you to evaluate the technical expertise of your
team, the data that is to be migrated, and the allowable downtime for the database during the
migration. In general, using DBUA will be the method of choice for very large databases, whereas
smaller databases may use an indirect method.
Before Upgrading
Prior to beginning the migration, you should back up the existing database and database software.
If the migration fails for some reason and you are unable to revert the database or software to its
earlier version, you will be able to restore your backup and re-create your database.
Chapter 2: Upgrading to Oracle Database 11g 53
You should develop and test scripts that will allow you to evaluate the performance and
functionality of the database following the upgrade.
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