Oracle Database 11g: Scheduler Student Guide

Some customers need to create hundreds of jobs each second. With regular jobs, each job creates a
database object describing the job, modifying several tables, and creating redo in the process. In the
Oracle Database 11g Scheduler, there is a persistent lightweight job. The goal of a lightweight job is
to reduce the overhead and the time required to start a job. A minimal amount of metadata is created
for the job. This reduces the time required and the redo created when the job starts.
To achieve these goals, the lightweight job has a small footprint on disk for the job metadata and for
storing run-time data. The footprint on disk also makes recovery and load balancing possible in RAC
environments. The lightweight job is always created from a job template, which can be a stored
procedure or a program. The stored procedure holds all the information needed for the job. A few job
attributes may be set (such as job arguments).
Job templates are created by using the DBMS_SCHEDULER.CREATE_PROGRAM procedure.
Oracle Database 11g continues to support the database object-based jobs that have existed since
Oracle Scheduler was first introduced in Oracle 10g. Lightweight jobs are not intended to replace
these jobs because each job type has its own advantages and gives you the flexibility to choose a job
based on your needs.

job and can also use programs or stored procedures owned by other users. A
regular job requires the job database object to be created and dropped. This action updates
several tables and the associated redo. Users who are creating a relatively small number of jobs
that run relatively infrequently should choose regular jobs.
• A persistent lightweight job has a significant improvement in create/drop time because it does
not have the overhead of creating a database object. Every lightweight job is created from a job
template, which is stored as a program. Because persistent lightweight jobs write state
information to disk at run time, only a small improvement is expected in execution. There are
several limitations to persistent lightweight jobs:
- Users cannot set privileges on these jobs. Instead, they inherit their privileges from the
parent job template.
- The use of a template is mandatory. It is not possible to create a fully self-contained
persistent lightweight job…………

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