OCP-1Z0-052-V8.02-63题

63. Examine the values for the following initialization parameters:
FAST_START_MTTR_TARGET = 0
LOG_CHECKPOINT_INTERVAL = 0
Which two will be the implications of these values in your database? (Choose two.)
A.The SGA advisor will be disabled.
B.The MTTR advisor will be enabled.
C.Automatic checkpoint tuning will be disabled.
D.Checkpoint information will not be written to the alert log file.
Answer: BC
答案解析：
此题的答案有误。







Enabling MTTR Advisor

To enable MTTR Advisor, set the two initialization parameters

STATISTICS_LEVEL

and

FAST_START_MTTR_TARGET

.

STATISTICS_LEVEL

governs whether all advisors are enabled and is not specific to MTTR Advisor. Ensure that it is set to

TYPICAL

or

ALL

. Then, when

FAST_START_MTTR_TARGET

is set
to a nonzero value, the MTTR Advisor is enabled

Automatic Checkpoint Tuning in 10g [ID 265831.1]
How to enable:
Automatic checkpoint tuning is enabled by default. If it is disabled, by setting the
parameter to zero explicitly, you can enable it by unsetting FAST_START_MTTR_TARGET or
set it to a nonzero value. If you set this parameter to zero this feature will be disabled.
Note: this is different from defaulting (i.e. not setting) fast_start_mttr_target to 0.
有官方文件看出，

FAST_START_MTTR_TARGET

为0是禁用的，故本题的B是错误的，图中的B的正确的。为C也是正确的。
参考：/article/1629004.html

MTTR 指导可将FAST_START_MTTR_TARGET值转换为多个参数，以便在所需时间内（或者在尽量接近此时间的范围内）启用实例恢复。请注意，将
FAST_START_MTTR_TARGET参数显式设置为0会禁用MTTR 指导。
FAST_START_MTTR_TARGET参数的设置值必须支持系统的服务级协议。如果MTTR 目标的值较小，则会因增加了数据文件写入次数而增加I/O 开销（这会影响性能）。但是，如果MTTR 目标设置得过大，则实例在崩溃后需要花费较长的时间才会恢复。

而快速启动检查点功能是通过指定所需的非零恢复平均时间（MTTR）值来启用的，该值将用于设置FAST_START_MTTR_TARGET初始化参数。此参数控制数据库对单个实例执行崩溃恢复所花费的时间量。启用快速启动检查点功能时，oracle将自动保持检查点的速度，已便达到请求的MTTR.如果将该值设置为0，将禁用此功能。