QUESTION 159
Which statement about Automatic Memory Management with Oracle 11g is true?
A. You cannot specify MEMORY_TARGET if you explicitly specify SGA_TARGET or
PGA_AGGREGATE_TARGET values that are greater than zero in your parameter file.
B. Oracle can reallocate memory between the SGA and PGA automatically as needed.
C. To use Automatic Memory Management, you must explicitly set both the MEMORY_TARGET and
MEMORY_MAX_TARGET parameters in your parameter file.
D. You can set the MEMORY_TARGET parameter to a maximum value of the current SGA size plus the
current PGA size.
Answer: B
同494题：http://blog.csdn.net/rlhua/article/details/12496463
Explanation/Reference:
Section: Managing Database Performance & Tuning
When Automatic Memory Management is enabled in Oracle 11g, Oracle can reallocate memory between the
SGA and PGA automatically as needed. Using Automatic Memory Management can reduce the chances of
being unable to allocate memory to SGA and PGA memory structures. You can enable Automatic Memory
Management by setting the MEMORY_TARGET initialization parameter or using Enterprise Manager.
The option that states you cannot specify MEMORY_TARGETif you explicitly specify SGA_TARGETor
PGA_AGGREGATE_TARGETvalues that are greater than zero in your parameter file is incorrect. If you explicitly
set SGA_TARGETand PGA_AGGREGATE_TARGET, the MEMORY_TARGETvalue will default to the sum of the
two, but can be increased up to the value of MEMORY_MAX_SIZE. If you set MEMORY_TARGET, you can also set
SGA_TARGET, PGA_AGGREGATE_TARGET, both SGA_TARGETand PGA_AGGREGATE_TARGET, or neither of the
two.
How Oracle manages memory and sets the defaults forother memory parameters depends on which
parameters you specify. If you set only the MEMORY_TARGET, and leave the SGA_TARGETand
PGA_AGGREGATE_TARGETparameters unset, Oracle automatically allocates 60 percent of available memory
to the SGA and 40 percent of available memory to the PGA when the database starts. If you set
MEMORY_TARGETand PGA_AGGREGATE_TARGETbut not SGA_TARGET, SGA_TARGETis set to either the
SGA_MAX_SIZEvalue or the value of MEMORY_TARGET- PGA_AGGREGATE_TARGET, whichever is smaller. If
you set MEMORY_TARGETand SGA_TARGETbut not PGA_AGGREGATE_TARGET, PGA_AGGREGATE_TARGETis
set to a value of MEMORY_TARGET- SGA_TARGET.
The option that states to use Automatic Memory Management you must explicitly set both the
MEMORY_TARGETand MEMORY_MAX_TARGETparameters in your parameter file is incorrect. Youonly need to
set MEMORY_TARGET. If you specify a nonzero value for MEMORY_TARGETand do not set
MEMORY_MAX_TARGET, MEMORY_MAX_TARGETwill be set to the same value as MEMORY_TARGETby default.
The option that states you can set the MEMORY_TARGETparameter to a maximum value of the current SGA
size plus the current PGA size is incorrect. You can increase MEMORY_TARGETup to the value of
MEMORY_MAX_SIZE.