Chapter 11. Managing Resources

ORACLE DATABASE 10G: ADMINISTRATION II EXAM OBJECTIVES COVERED IN THIS CHAPTER:

• Managing Resources

  • Configure the Resource Manager.

  • Assign users to Resource Manager groups.

  • Create resource plans within groups.

  • Specify directives for allocating resources to consumer groups.

As a database administrator, it is your job to maintain a given level of performance from the database. To successfully accomplish this mission requires close management of scarce hardware resources.

In the past, management of Oracle resources fell upon the operating system. The operating system not only had to juggle resources between the different Oracle processes, but also between Oracle and all other processes running on the system. As if that weren't enough, it also had no way of differentiating one Oracle process from another. Therefore, allocating resources between user groups or applications was impossible.

In addition, resource management performed by the operating system has a tendency to cause certain performance problems. Excessive context switching can occur when the number of server processes is high. Server processes holding latches can be de-scheduled, resulting in further inefficiency. And inappropriate resource allocation is common, due to the inability to prioritize Oracle tasks.

Oracle's Database Resource Manager (DRM) circumvents the inefficient operating system management process by giving the Oracle database server more control over resource management decisions. It also allows you to distribute available system resources among your users and applications based on business needs (or whatever criteria you wish to base it on).

This chapter describes the different elements of DRM and how to use them. In the overview section, you'll learn about the elements that comprise the DRM and see, at a high level, how they interact. You will be introduced to the pending area, a work area that must be established prior to the creation or modification of DRM objects.

Next, you will learn about resource consumer groups, which allow you to classify users based on their resource requirements. You'll learn how to set up resource plans that direct the allocation of resources among the resource consumer groups. You'll learn about resource allocation options offered by the database and the methods you can define to apply them.

You will also learn about resource plan directives that associate resource consumer groups, resource plans, and resource allocation methods. Finally, you'll learn the PL/SQL interface to manage DRM, as well as the views available to query DRM information.

Keep in mind when reading this chapter that the elements of DRM constitute a "chicken or the egg" situation in terms of the ordering of the topics. For instance, the pending area must be established before anything else is done. However, discussion of the pending area assumes knowledge of the objects defined later in the chapter. In the interest of organization and ease of use, each topic will be covered separately in its own section. Then, a final section will show how the elements integrate.