Tuning Oracle 11g Databases

This section provides information about tuning Oracle 11g databases.

Automatic Memory Management (AMM)

Beginning with version 11g, the Oracle database can automatically manage the SGA memory and the instance PGA memory. You only need to designate the total memory size to be used by the instance, and the Oracle database will dynamically exchange memory between the SGA and the instance PGA as needed to meet processing demands. This capability is referred to as automatic memory management. With this memory management method, the database also dynamically tunes the sizes of the individual SGA components and the sizes of the individual PGAs.

AMM is implemented using Memory_Target and Memory_max_target parameters. Use of MEMORY_MAX_TARGET is optional. When MEMORY_MAX_TARGET is not set, Oracle automatically sets MEMORY_MAX_TARGET to the value of MEMORY_TARGET.

To switch to AMM, define the value of MEMORY_TARGET in the spfile. It is important to ensure that the values of SGA_TARGET and PGA_AGGREGATE_TARGET are set to 0. Customers upgrading to 11g instance must set the value of SGA_TARGET and PGA_AGGREGATE_TARGET to 0.