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

Job environment

Don't make any assumptions about the environment your job runs in. Oracle has made lots of changes with regards to the environment the job gets when it is launched outside the database. In 9i, there is a Java method that enables us to start a job on the operating system that has lots of information in the environment. This environment got poorer with each upgrade. In earlier releases, ORACLE_HOME, PATH, and ORACLE_SID were defined and PWD was in $ORACLE_HOME/dbs. In 10g, these three variables disappeared. In 11gR1, the current directory of processes scheduled (using the remote external job agent), is the current directory at the time the agent started. So, you should not rely on any variable in the environment.

Before you start using external jobs, think about how the job should define its own environment. Don't forget about the ulimits, they also tend to change between releases. Even something as simple as a change in the stack size (limit -s) can have surprising consequences...