Oracle 视图 DBA_ADVISOR_RECOMMENDATIONS 官方解释，作用，如何使用详细说明

视图

Oracle视图DBA_ADVISOR_RECOMMENDATIONS是在数据库客户端提供的一种特殊视图，它显示给定数据库中正在执行的建议者的推荐结果。通过此视图可以查询出一些重要的建议，例如在某些特定情况下是否需要经常进行统计更新、或者是否需要运行特定的统计收集计划、或者提示用户完成某些数据库的优化等等。这些建议有助于用户改善系统的性能。使用方法：

1. 在sqlplus 进入数据库并登录，执行如下查询：

SELECT task_name, execution_start, execution_end, recommendations FROM dba_advisor_recommendations;

2. 查看输出结果，根据结果进行相应的优化。

官方英文解释

DBA_ADVISOR_RECOMMENDATIONS displays the results of an analysis of all recommendations in the database.

A recommendation can have multiple actions associated with it. Actions are described in the DBA_ADVISOR_ACTIONS view. A recommendation also points to a set of rationales that present a justification/reasoning for that recommendation. These rationales are in the DBA_ADVISOR_RATIONALE view.

Related View

USER_ADVISOR_RECOMMENDATIONS displays the results of an analysis of the recommendations owned by the current user. This view does not display the OWNER column.

Ranking, in terms of importance, within the set of recommendations generated for the task

Comma-separated list of the recommendation IDs of the parent recommendations. If this column is nonzero, then the recommendation depends on the parents, and cannot be accepted if the parents are not accepted.

Describes the benefit obtained by carrying out the recommendation

If there is a set of parents for the recommendation, then the benefit is the cumulative benefit (the improvement in system performance when this and all prior parent recommendations are accepted).

If there are no parents, then this is the improvement when the recommendation is accepted, independent of other recommendations.

Calculated benefit value

This column displays an estimate of the savings in total activity (or load) on the system if all actions of the recommendation are implemented.

Recommendations are not additive, that is, the benefit from one recommendation may overlap with the benefit from another. For example, Oracle might recommend increasing the shared pool size, or reducing hard parses (by not using literals), and both recommendations might reduce the same part of the workload related to parsing.

The benefit is given in both pure active sessions and as a percent of the average active sessions of the analysis time period. Therefore, if the benefit is 20% of active sessions, Oracle estimates that if you apply the actions on the same workload, the average active sessions on the server will be reduced by 20%. The DBA_ADDM_TASKS view displays the average active sessions for an ADDM task.

When a task is complete, the recommendations are marked ACCEPT. The status can be changed later using the MARK_RECOMMENDATION procedure:

ACCEPT Current recommendation is ready to implement. This recommendation can also be used as advice for future analysis operations.

REJECT Current recommendation is not acceptable to the user, and therefore will be excluded from any implementation scripts. This recommendation can also be used as advice for future analysis operations.

IGNORE Though not rejected, the current recommendation will be ignored when generating scripts and will never be used as advice to future analysis operations.

A value of Y means that the row in the view was filtered out by a directive (or a combination of directives). A value of N means that the row was not filtered.

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数据库远程运维 Oracle 视图 DBA_ADVISOR_RECOMMENDATIONS 官方解释，作用，如何使用详细说明