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Oracle Replication Tips by Burleson |
The Oracle replication Job Scheduler
It is important to understand the job scheduler and how it works
because Oracle uses the job scheduler to refresh the data within the
Oracle Materialized Views.
From the DBA’s perspective, it’s important to ensure
that replication jobs are not broken, which implies that they are
failing. A broken job will halt the updates of the Materialized
Views
causing the data in the Materialized View
to become stale. Let’s look at the job scheduler in a bit more detail.
A Refresher on The Oracle Job Scheduler
The Oracle job scheduler is an internal database process that allows
jobs to be scheduled within Oracle. Oracle provides the
dbms_job
package and Oracle views to manage the job scheduler.
Within the job scheduler, a job can execute any procedure or
function that is accessible. Each job is executed using an Oracle
background process. The number of available concurrent background
processes is defined by the database initialization parameter
job_queue_processes.
JOB_QUEUE_PROCESSES = 5
When the database is started, the number of job queue processes
defined by job_queue_processes will start.
In Oracle9i, a job queue coordinator process (CJQO) is spawned at
database startup as well. On a regular basis, the CJQO checks for
jobs that are ready to run within the job scheduler. By default,
this check occurs every 5 seconds. If you need to modify this
setting, you can
This is an
excerpt from Oracle Replication By Rampant TechPress (only $19.95).
You can click here to order a copy and get instant access to the code
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