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About the Memory Advisors
Adequate physical memory has a significant impact on the performance of your
Oracle Database. With its automatic memory management capabilities, Oracle
Database can automatically adjust the memory distribution among the various SGA
and PGA components for optimal performance. These adjustments are made within
the boundaries of the total amount of memory that you allocate to the database.
ADDM periodically evaluates the performance of your database to determine
performance problems. If ADDM finds that the current amount of available memory is
inadequate and adversely affecting performance, then it can recommend that you
increase memory allocations. You can select new memory allocations using the
Memory Advisors.
Additionally, you can use the Memory Advisors to perform what-if analysis on the
following:
■ The database performance benefits of adding physical memory to your database
■ The database performance impact of reducing the physical memory available to
your database
With the Memory Advisors, you can obtain memory sizing advice as follows:
■ If automatic memory management is enabled, you can get a prediction of the
percentage of time saved by using a different target memory size setting for the
Oracle instance.
See "Modifying Memory Settings - Automatic Memory Management" on
page 5-17 for more information.
■ If automatic memory management is disabled and automatic shared memory
management is enabled, you can get a prediction of the percentage of time saved
by using a different total SGA size.
See "Modifying Memory Settings - Automatic Shared Memory Management" on
page 5-21 for more information.
■ If only manual shared memory management is enabled, then you can get a
prediction of the percentage of reads saved by using a different database cache
size.
See "Modifying Memory Settings - Manual Shared Memory Management" on
page 5-23 for more information.
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