63.Examine the values for the following initialization parameters: FAST_START_MTTR_TARGET = 0 LOG_CH
来源：互联网 发布：有安卓调音软件吗 编辑：程序博客网 时间：2024/06/05 17:00
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.
答案：BC
解析：
其实从数据库启动日志中可以看到这么一句
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
SQL> show parameter mttr
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_mttr_target integer 0
从这里可以看出，数据库设置的fast_start_mttr_target为0，从alter日志中可以看出它没有启动
可以通过设置fast_start_mttr_target来强制产生检查点，它的单位是秒，表示实例恢复的时间不会超过15秒
并且启动了mttr advisor
SELECT TARGET_MTTR,ESTIMATED_MTTR,CKPT_BLOCK_WRITES FROM V$INSTANCE_RECOVERY;
--这里可以通过target_mttr查看具体给出的建议
The TARGET_MTTR field of V$INSTANCE_RECOVERY contains the MTTR target in effect.
The ESTIMATED_MTTR field of V$INSTANCE_RECOVERY contains the estimated MTTR should a crash happen right away.
--那么从这里看出，B应该也不对，并且可以从下面的文档中找到对应的说明
参考：http://docs.oracle.com/cd/E11882_01/server.112/e41573/instance_tune.htm#PFGRF13015
10.5.3.3.1 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.
说明B不正确,
这里说明一下mttr和Automatic checkpoint tuning
提高系统效率和数据库一致性，引入了校验点的事件，CKPT是在DBWR将高速缓冲中的数据写入到数据文件上的时候产生的，理论上说它是不需要的
可以通过redo log和 scn 保证了完全恢复，引入它是为了提高效率，因为所有的校验点为止的变化都已经写入到数据文件中了，在恢复的时候
校验点之前的重做日志就不在需要了，这样实例恢复就加快了，CKPT会将校验点写入到所有相关的数据文件的文件头中，还要将
校验点号码、重做日志序列号、归档日志名称和最低、最高scn号都会写入控制文件中，由于ckpt会产生大量的IO操作,什么时候会发生ckpt
在redo切换的时候，就会执行ckpt的，那么如果ckpt越频繁，说明出现故障需要恢复的时间就越短，这个是成正比的
因此这里就有了Automatic checkpoint tuning，它有两个参数一个是LOG_CHECKPOINT_TIMEOUT，一个是LOG_CHECKPOINT_INTERVAL
LOG_CHECKPOINT_TIMEOUT指的是时间，LOG_CHECKPOINT_INTERVAL指的是大小，如果指定后那么就会Automatic checkpoint tuning
这个时候就不止切换redo的时候触发ckpt了，mttr的意思是（mean time to restoration）指平均恢复时间，
这里可以设置fast_start_mttr_target来指定，这个时候就会打开mttr advisor，并且给出相应的建议，
但是从文档中可以看到这么一句FAST_START_MTTR_TARGET enables you to specify the number of seconds the database takes to perform crash recovery of a single instance. When specified, FAST_START_MTTR_TARGET is overridden by LOG_CHECKPOINT_INTERVAL.
意思就是如果设置了LOG_CHECKPOINT_INTERVAL，那么fast_start_mttr_target会被覆盖。
这里有几个问题，如果设置了LOG_CHECKPOINT_TIMEOUT得话，Automatic checkpoint tuning会不会打开
所以这里c也不太确定
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.
答案：BC
解析：
其实从数据库启动日志中可以看到这么一句
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
SQL> show parameter mttr
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_mttr_target integer 0
从这里可以看出，数据库设置的fast_start_mttr_target为0，从alter日志中可以看出它没有启动
可以通过设置fast_start_mttr_target来强制产生检查点，它的单位是秒，表示实例恢复的时间不会超过15秒
并且启动了mttr advisor
SELECT TARGET_MTTR,ESTIMATED_MTTR,CKPT_BLOCK_WRITES FROM V$INSTANCE_RECOVERY;
--这里可以通过target_mttr查看具体给出的建议
The TARGET_MTTR field of V$INSTANCE_RECOVERY contains the MTTR target in effect.
The ESTIMATED_MTTR field of V$INSTANCE_RECOVERY contains the estimated MTTR should a crash happen right away.
--那么从这里看出，B应该也不对，并且可以从下面的文档中找到对应的说明
参考：http://docs.oracle.com/cd/E11882_01/server.112/e41573/instance_tune.htm#PFGRF13015
10.5.3.3.1 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.
说明B不正确,
这里说明一下mttr和Automatic checkpoint tuning
提高系统效率和数据库一致性，引入了校验点的事件，CKPT是在DBWR将高速缓冲中的数据写入到数据文件上的时候产生的，理论上说它是不需要的
可以通过redo log和 scn 保证了完全恢复，引入它是为了提高效率，因为所有的校验点为止的变化都已经写入到数据文件中了，在恢复的时候
校验点之前的重做日志就不在需要了，这样实例恢复就加快了，CKPT会将校验点写入到所有相关的数据文件的文件头中，还要将
校验点号码、重做日志序列号、归档日志名称和最低、最高scn号都会写入控制文件中，由于ckpt会产生大量的IO操作,什么时候会发生ckpt
在redo切换的时候，就会执行ckpt的，那么如果ckpt越频繁，说明出现故障需要恢复的时间就越短，这个是成正比的
因此这里就有了Automatic checkpoint tuning，它有两个参数一个是LOG_CHECKPOINT_TIMEOUT，一个是LOG_CHECKPOINT_INTERVAL
LOG_CHECKPOINT_TIMEOUT指的是时间，LOG_CHECKPOINT_INTERVAL指的是大小，如果指定后那么就会Automatic checkpoint tuning
这个时候就不止切换redo的时候触发ckpt了，mttr的意思是（mean time to restoration）指平均恢复时间，
这里可以设置fast_start_mttr_target来指定，这个时候就会打开mttr advisor，并且给出相应的建议，
但是从文档中可以看到这么一句FAST_START_MTTR_TARGET enables you to specify the number of seconds the database takes to perform crash recovery of a single instance. When specified, FAST_START_MTTR_TARGET is overridden by LOG_CHECKPOINT_INTERVAL.
意思就是如果设置了LOG_CHECKPOINT_INTERVAL，那么fast_start_mttr_target会被覆盖。
这里有几个问题，如果设置了LOG_CHECKPOINT_TIMEOUT得话，Automatic checkpoint tuning会不会打开
所以这里c也不太确定
0 0
- 63.Examine the values for the following initialization parameters: FAST_START_MTTR_TARGET = 0 LOG_CH
- 74.The database is running in ARCHIVELOG mode. Examine the initialization parameters and their value
- 36.Examine the following SQL commands:
- 58.View the Exhibit and examine the parameters.
- 161 Examine the following command used to perform incremental level 0 backup: RMAN> BACKUP INCREMENT
- 117.View the Exhibit and examine the initialization parameter settings. Which three initialization p
- 188 Examine the following scenario: The target database instance is running. The most recent backup
- 10.Examine the following statement that is used to modify the constraint on the SALES table:
- 46: Which two statements are true about setting the FAST_START_MTTR_TARGET initialization parameter
- 64.Which two statements are true about setting the FAST_START_MTTR_TARGET initialization parameter t
- Failed to compile resources with the following parameters
- 23.Examine the structure proposed for the TRANSACTIONS table:
- 24.Examine the structure proposed for the TRANSACTIONS table:
- 53.You set the following parameters in the parameter file and restarted the database: MEMORY_MAX_TAR
- Examine the following statement that is used to modify the primary key constraint on the SALES tabl
- 55.View the Exhibit to examine the output produced by the following query at three different times s
- 156.Examine the following steps performed on a database instance: 1: The DBA grants the CREATE TABL
- QUESTION 105 Examine the following RMAN script: RMAN> run { debug on; allocate channel c1 type disk;
- bootstrap 中 dataTable 首页点击事件可用、下一页后点击事件无效
- 扩展kmp详解
- LeetCode-96:Unique Binary Search Trees
- db2 存储过程及函数总结
- svn远程连接失败
- 63.Examine the values for the following initialization parameters: FAST_START_MTTR_TARGET = 0 LOG_CH
- <Entity Framework> - 直接执行数据库命令
- OpenLayers3入门篇-单击事件
- 移动端自适应
- 下拉刷新+加载更多的ListView(直接拿来用)
- Imgproc_3_图像变换
- jQuery函数attr()和prop()的区别
- JavaWeb登陆验证码
- Mac 终端自动补全忽略大小写
