Book Image

Mastering Oracle Scheduler in Oracle 11g Databases

By : Ronald Rood
Book Image

Mastering Oracle Scheduler in Oracle 11g Databases

By: Ronald Rood

Overview of this book

Scheduler (DBMS_SCHEDULER) is included in Oracle Database and is a tool for the automation, management, and control of jobs. It enables users to schedule jobs running inside the database such as PL/SQL procedures or PL/SQL blocks, as well as jobs running outside the database like shell scripts. Scheduler ensures that jobs are run on time, automates business processes, and optimizes the use of available resources. You just need to specify a fixed date and time and Scheduler will do the rest. What if you don't know the precise time to execute your job? Nothing to worry about, you can specify an event upon which you want your job to be done and Scheduler will execute your job at the appropriate time. Although scheduling sounds quite easy, it requires programming skills and knowledge to set up such a powerful, intelligent scheduler for your project. This book is your practical guide to DBMS_SCHEDULER for setting up platform-independent schedules that automate the execution of time-based or event-based job processes. It will show you how to automate business processes, and help you manage and monitor those jobs efficiently and effectively. It explains how Scheduler can be used to achieve the tasks you need to make happen in the real world. With a little understanding of how the Scheduler can be used and what kind of control it gives, you will be able to recognize the real power that many known enterprise-class schedulers ñ with serious price tags ñ cannot compete with. You will see how running a specific program can be made dependent on the successful running of certain other programs, and how to separate various tasks using the built-in security mechanisms. You will learn to manage resources to balance the load on your system, and gain increased database performance.
Table of Contents (15 chapters)
Mastering Oracle Scheduler in Oracle 11g Databases
About the Author
About the Reviewers

Evaluation interval

As Steven Jobs would often say:

There is one more thing ...

There is one more thing to say about rules. The Scheduler normally checks what to do at the start and the end of each and every job step. In many situations this may be good enough, but there are situations where something more is required. One example is where one step of a job not only depends on the status of a former step, but also on the row count of a table or on the time of day. If this is the case, it would be best if the job step starts running as soon as the condition becomes true; and not after we had to manually intervene to make the Scheduler evaluate the chain again. We can give the chain an evaluation interval to make the Scheduler not only check the status of the job when it starts the job (or a job_step ends), but also to repeat the evaluations on a timed basis. To run these repeated evaluations, we have to specify evaluation_interval. The evaluation interval is the way to make the Scheduler check...