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" 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" 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" for more information.