oracle 11g 新参数 MEMORY_TARGET

MEMORY_TARGET

PropertyDescriptionParameter typeBig integerSyntaxMEMORY_TARGET= integer[K | M | G]Default value0 (SGAautotuning is disabled for DEFERRED mode autotuningrequests, but allowed for IMMEDIATE mode autotuningrequests)ModifiableALTERSYSTEMRange of values152 MB toMEMORY_MAX_TARGETBasicNo

MEMORY_TARGET specifies the Oracle system-wideusable memory. The database tunes memory to theMEMORY_TARGET value, reducing or enlarging the SGA andPGA as needed.

In a text-based initialization parameter file, if you omitMEMORY_MAX_TARGET and include a value forMEMORY_TARGET, then the database automatically setsMEMORY_MAX_TARGET to the value ofMEMORY_TARGET. If you omit the line forMEMORY_TARGET and include a value forMEMORY_MAX_TARGET, the MEMORY_TARGETparameter defaults to zero. After startup, you can then dynamicallychange MEMORY_TARGET to a nonzero value, provided thatit does not exceed the value of MEMORY_MAX_TARGET.

Total memory usage can grow beyond the value ofMEMORY_TARGET. For example, memory is allocated toPL/SQL tables and varrays regardless of the value ofMEMORY_TARGET as long as memory is available at theoperating system level.

In the Default value field,IMMEDIATE mode autotuning requests are necessary toavoid ORA-04031errors. The DEFERRED and IMMEDIATE modesare reflected in the OPER_MODE column of theV$MEMORY_RESIZE_OPS view.

Note:

The default value of SGA_MAX_SIZE depends on thevalues of MEMORY_TARGET andMEMORY_MAX_TARGET.