Oracle 视图 V$MTTR_TARGET_ADVICE 官方解释，作用，如何使用详细说明
本站中文解释
Oracle视图V$MTTR_TARGET_ADVICE用于显示平均恢复时间目标的各项提示和建议。它的信息包括目标的活动状态，目标的百分比在指定的MTTR (归档恢复时间) 级别，目标状态是否执行预期，以及允许的恢复时间范围。该视图还提供恢复时间和恢复内存块大小建议。可以利用这些信息来优化MTTR，以提高性能。
使用V$MTTR_TARGET_ADVICE视图可以获得Oracle数据库中所有记录在MTR (平均迁移修复时间) 目标中的情况。如果一个数据库管理员需要检查系统的归档耐久度，他可以使用MTTR_TARGET_ADVICE 全局视图来识别实际的恢复时间或可能的恢复时间预测。
通常，用户可以通过查询V$MTTR_TARGET_ADVICE视图来确定当前MTR建议，包括活动目标状态，活动目标与实际数据库恢复时间之间的时间差值等比例，以及可能恢复时间的预测、所建议的起始和最终恢复时间等信息。
官方英文解释
V$MTTR_TARGET_ADVICE displays rows that predict the number of physical I/Os for the MTTR corresponding to each row.
The rows also compute a physical I/O factor, which is the ratio of the number of estimated I/Os to the number of I/Os actually performed by the current MTTR setting during the measurement interval.
The content of the view is empty if MTTR advisory has not been turned on since database startup. Otherwise, it returns the advisory information collected. If advisory is currently off, then this information comes from the last time MTTR advisory was on. FAST_START_MTTR_TARGET must be set to a nonzero value if the STATISTICS_LEVEL parameter is dynamically modified to turn MTTR advisory on.
If the FAST_START_MTTR_TARGET parameter is changed while MTTR advisory is on, then MTTR advisory is temporarily turned off until the new FAST_START_MTTR_TARGET setting takes effect. During this transition period, the contents of V$MTTR_TARGET_ADVICE reflect the simulation result for the old MTTR setting.
| Column | Datatype | Description |
|---|---|---|
|
|
|
MTTR setting being simulated. Equal to the current MTTR setting if this is the first row of the view. |
|
|
|
Current status of MTTR simulation:
|
|
|
|
Dirty buffer limit derived from the MTTR being simulated |
|
|
|
Estimated number of cache physical writes under this MTTR |
|
|
|
Estimated cache physical write ratio under this MTTR. It is the ratio of the estimated number of cache writes to the number of cache writes under the current MTTR setting. |
|
|
|
Estimated total number of physical writes under this MTTR |
|
|
|
Estimated total physical write ratio under this MTTR. It is the ratio of the estimated total number of physical writes to the total number of physical writes under the current MTTR setting. |
|
|
|
Estimated total number of I/Os under this MTTR |
|
|
|
Estimated total I/O ratio under this MTTR. It is the ratio of the estimated total number of I/Os to the total number of I/Os under the current MTTR setting. |
|
|
|
The ID of the container to which the data pertains. Possible values include:
|
See Also:
-
“FAST_START_MTTR_TARGET”
-
“STATISTICS_LEVEL”
