If
you use packaged applications, you will need to base your kernel version upgrade plans on the
vendor??™s support for the different Oracle versions. Furthermore, the vendor may switch the optimizer
features it supports??”for example, requiring that your COMPATIBLE parameter be set to a specific
value. Your database environment will need to be as flexible as possible in order to support these
changes.
Because of these restrictions outside of your control, you should attempt to isolate the
packaged application to its own instance. If you frequently query data across applications, the
isolation of the application to its own instance will increase your reliance on database links. You
need to evaluate the maintenance costs of supporting multiple instances against the maintenance
costs of supporting multiple applications in a single instance.
Execution Plans
Generating execution plans requires accessing the SQL statements that are run against the database.
The shared SQL area in the SGA maintains the SQL statements that are executed against the
database (accessible via the V$SQL_PLAN view). Matching the SQL statements against specific parts
of the application is a time-consuming process. You should attempt to identify specific areas whose
functionality and performance are critical to the application??™s success and work with the package??™s
162 Oracle Database 11g DBA Handbook
support team to resolve performance issues.
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