Windows and Windows Group in Oracle

Reference documents:

Http://www.5ienet.com/note/html/scheduler/oracle-scheduler-using-window.shtml

Window concept

This Windows is not windows, usually said Windows refers to cover the richest of the operating system, and here said Windows, refers to a scheduler attribute in a subkey. In scheduler, window corresponds to the concept of a time window.

We know that ordinary jobs does not have the concept of running time management, meaning that after a job is started, the user can only passively wait for it to execute until the task is completed (or the DBA manually kill the corresponding process), during which The job that is executed will compete with other active processes for resources in the current system. For large database systems, system resources that is quite valuable intangible assets, how can anyone say that use, when you want to use the time, there is no plan without a bit of moderation this also has. You also don't say, before 9i, is really this thing, who want to use, who also can not control, which said the most is job. Do you remember job Classes, yes? Defining job Classes does control the resources that the job can use, but using job Classes alone does not provide the flexibility to control the job to use the right resources at the right time. After entering 10g, the Scheduler provided window, and things finally eased.

Window can specify a time window during which the resources that are dictated (used) by the job execution can be effectively controlled by combining with the job classes. For example, if the job is usually performed at a low-dawn server load, then the window can be set to allow jobs to use more system resources, and after working hours, if the job is still not completed, assign another limited resource to it. To minimize the impact of the resources occupied by job execution on other businesses.

Windows Group Concepts

In addition to window, there is a window group that is associated with window, and a window group may contain multiple windows. The intent of using window group is that if a job executes for a long time or even 24 hours a day, it is difficult for a single window to effectively adjust its resource footprint for such jobs, and by setting up a window group, The window group contains multiple windows, each of which is responsible for resource usage schedules at different points in time.

Then, when creating the job, specify the name of the window group for the Schedule_name parameter (unexpectedly schedule_name can also be specified as window group, in fact, more than window group, can also be directly designated as window), In this way, the job can be associated with the window in a very simple manner.

The creation and management of WINDOW GROUP is very similar to the approach described earlier:

• Create, use create_window_group process;
• Delete, use drop_window_group process;
• Add a WINDOW member and use the add_window_group_member process;
• Delete the WINDOW member and use the remove_window_group_member process;
• Enable, use the Enable process;
• Disable, use the Disable process;

The invocation of these procedures is also very simple, here is not focused on the demonstration, interested friends may wish to try their own.