053试题 158/449/637 - Scheduler Window

题目：

158.You create two resource plans, one for data warehouse loading jobs at night and the other for
application jobs at day time. You want the resource plans to activate automatically so that the resource
allocation is optimum as desired by the activity.
How would you achieve this?
A. Implement job classes
B. Implement Scheduler windows
C. Implement the mapping rule for the consumer groups
D. Set the SWITCH_TIME resource plan directive for both the resource plans

参考文档 B
解析
题目意思，创建了两个资源计划，一个在晚上运行job，用于数据仓库，一个用于应用程序job，白天运行。
希望资源计划自动激活，以便根据活动的需要优化资源分配。为你怎么做？
使用scheduler window。选择 B。

参考文档：

https://docs.oracle.com/cd/E11882_01/server.112/e25494/dbrm.htm#ADMIN11890

Automatic Enabling of the Resource Manager by Oracle Scheduler Windows

The Resource Manager automatically activates if an Oracle Scheduler window that specifies a resource plan opens. When the Scheduler window closes, the resource plan associated with the window is disabled, and the resource plan that was running before the Scheduler window opened is reenabled. (If no resource plan was enabled before the window opened, then the Resource Manager is disabled.) In an Oracle Real Application Clusters environment, a Scheduler window applies to all instances, so the window's resource plan is enabled on every instance.

Note that by default a set of automated maintenance tasks run during maintenance windows, which are predefined Scheduler windows that are members of the MAINTENANCE_WINDOW_GROUP window group and which specify the DEFAULT_MAINTENANCE_PLAN resource plan. Thus, the Resource Manager activates by default during maintenance windows. You can modify these maintenance windows to use a different resource plan, if desired.

Note:

If you change the plan associated with maintenance windows, then ensure that you include the subplan ORA$AUTOTASK_SUB_PLAN and the consumer group ORA$DIAGNOSTICS in the new plan.

Windows

You typically create windows only when you are in the role of Scheduler administrator.

You create windows to automatically start jobs or to change resource allocation among jobs during various time periods of the day, week, and so on. A window is represented by an interval of time with a well-defined beginning and end, such as "from 12am-6am".

Windows work with job classes to control resource allocation. Each window specifies the resource plan to activate when the window opens (becomes active), and each job class specifies a resource consumer group or specifies a database service, which can map to a consumer group. A job that runs within a window, therefore, has resources allocated to it according to the consumer group of its job class and the resource plan of the window.

Figure 28-2 shows a workday that includes two windows. In this configuration, jobs belonging to the job class that links to Consumer Group 1 get more resources in the morning than in the afternoon. The opposite is true for jobs in the job class that links to Consumer Group 2.

Figure 28-2 Windows help define the resources that are allocated to jobs

Description of "Figure 28-2 Windows help define the resources that are allocated to jobs"

See Chapter 27, "Managing Resources with Oracle Database Resource Manager" for more information on resource plans and consumer groups.

You can assign a priority to each window. If windows overlap, the window with the highest priority is chosen over other windows with lower priorities. The Scheduler automatically opens and closes windows as window start times and end times come and go.

A job can name a window in its schedule_name attribute. The Scheduler then starts the job when the window opens. If a window is already open, and a new job is created that points to that window, the new job does not start until the next time the window opens.

Note:

If necessary, you can temporarily block windows from switching the current resource plan. For more information, see "Enabling Oracle Database Resource Manager and Switching Plans", or the discussion of the DBMS_RESOURCE_MANAGER.SWITCH_PLAN package procedure in Oracle Database PL/SQL Packages and Types Reference.

See Also:

"Creating Windows"

END

-- 2019-09-05 add

题目：

449.Which of the following objects can be directly referenced by a window object? (Choose all that apply.)
A. Schedule object
B. Program object
C. Job object
D. Resource plan
E. Resource consumer group

参考答案 AD（暂时没有搞明白）

参考文档

Creates a window using a named schedule object:

DBMS_SCHEDULER.CREATE_WINDOW (window_name             IN VARCHAR2,resource_plan           IN VARCHAR2,schedule_name           IN VARCHAR2,duration                IN INTERVAL DAY TO SECOND,window_priority         IN VARCHAR2 DEFAULT 'LOW',comments                IN VARCHAR2 DEFAULT NULL);

Creates a window using an inlined schedule:

DBMS_SCHEDULER.CREATE_WINDOW (window_name             IN VARCHAR2,resource_plan           IN VARCHAR2,start_date              IN TIMESTAMP WITH TIME ZONE DEFAULT NULL,repeat_interval         IN VARCHAR2,end_date                IN TIMESTAMP WITH TIME ZONE DEFAULT NULL,duration                IN INTERVAL DAY TO SECOND,window_priority         IN VARCHAR2 DEFAULT 'LOW',comments                IN VARCHAR2 DEFAULT NULL);

Parameters

Table 129-32 CREATE_WINDOW Procedure Parameters

Parameter	Description
`window_name`	The name to assign to the window. The name must be unique in the SQL namespace. All windows are in the `SYS` schema, so the preface '`SYS`' is optional.
`resource_plan`	This attribute specifies the resource plan that automatically activates when the window opens. When the window closes, the system switches to the appropriate resource plan, which is usually the plan that was in effect before the window opened, but can also be the plan of a different window. Only one resource plan can be associated with a window. It may be `NULL` or the empty string (""). When it is `NULL`, the resource plan in effect when the window opens stays in effect for the duration of the window. When it is the empty string, the resource manager is disabled for the duration of the window. If the window is open and the resource plan is dropped, then the resource allocation for the duration of the window is not affected.
`start_date`	This attribute specifies the first date and time on which this window is scheduled to open. If the value for `start_date` specified is in the past or is not specified, the window opens as soon as it is created. For repeating windows that use a calendaring expression to specify the repeat interval, the value for `start_date` is a reference date. The first time the window opens depends on the repeat interval specified and the value for `start_date`.
`duration`	This attribute specifies how long the window stays open. For example,`'interval '5' hour'` for five hours. There is no default value for this attribute. Therefore, if no value is specified when the window is created, an error occurs. The duration is of type interval day to seconds and ranges from one minute to 99 days.
`schedule_name`	This attribute specifies the name of the schedule associated with the window.
`repeat_interval`	This attribute specifies how often the window repeats. It is expressed using the Scheduler calendaring syntax. See "Calendaring Syntax" for more information. A PL/SQL expression cannot be used to specify the repeat interval for a window. The expression specified is evaluated to determine the next time the window opens. If no `repeat_interval` is specified, the window opens only once at the specified start date.
`end_date`	This attribute specifies the date and time after which the window no longer opens. When the value for `end_date` is reached, the window is disabled. In the`*_SCHEDULER_WINDOWS` views, the enabled flag of the window is set to `FALSE`. A non-repeating window that has no value for `end_date` opens only once for the duration of the window. For a repeating window, if no `end_date` is specified, then the window keeps repeating forever. The `end_date` must be after the `start_date`. If it is not, then an error is generated when the window is created.
`window_priority`	This attribute is only relevant when two windows overlap. Because only one window can be in effect at one time, the window priority determines which window opens. The two possible values for this attribute are '`HIGH`' and '`LOW`'. A high priority window has precedence over a low priority window, therefore, the low priority window does not open if it overlaps a high priority window. By default, windows are created with priority '`LOW`'.
`comments`	This attribute specifies an optional comment about the window. By default, this attribute is `NULL`.

END

-- 2019-09-11 add

题目：

637.Which three statements are true about windows? (Choose three.)
A. Only one window can be open at any given time
B. Consumer groups are associated with windows
C. Windows work with job classes to control resource allocation
D. The database service name must be provided during windows creation
E. Windows can automatically start job or change resource allocation among jobs for various time periods.

参考答案 ACE
关于Window，说法正确的是。