OCP-V13-521

QUESTION 521

You notice that a job in a chain has not completed on a nonconstrained RAC database. Which of
these are valid reasons why that might occur?
A. The job priority is 1 and the resource consumer group CPU emphasis allocation is a low percentage.
B. The job affinity is to a service and one node in that service is unavailable.
C. The job affinity is to an instance and that instance is unavailable.
D. There is no service affinity.
E. None of the above.
Correct Answer: C

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在一个无约束的RAC数据库上，你注意到一个数据库链没有完成，主要原因是什么 ?

C、 这个任务存活在其中一个实例上，而这个实例是无效的不运行的

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如果把JOB定义在INSTANCE级别上，JOB将运行在指定的实例上

http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_job.htm#i1001473

Working with Real Application Clusters
DBMS_JOB supports multi-instance execution of jobs. By default jobs can be executed on any instance, but only one single instance will execute the job. In addition, you can force instance binding by binding the job to a particular instance. You implement instance binding by specifying an instance number to the instance affinity parameter. Note, however, that in Oracle Database 10g Release 1 (10.1) instance binding is not recommended. Service affinity is preferred. This concept is implemented in the DBMS_SCHEDULER package.

The following procedures can be used to create, alter or run jobs with instance affinity. Note that not specifying affinity means any instance can run the job.

DBMS_JOB.SUBMIT
To submit a job to the job queue, use the following syntax:

DBMS_JOB.SUBMIT(
job OUT BINARY_INTEGER,
what IN VARCHAR2, NEXT_DATE IN DATE DEFAULTSYSDATE,
interval IN VARCHAR2 DEFAULT ‘NULL’,
no_parse IN BOOLEAN DEFAULT FALSE,
instance IN BINARY_INTEGER DEFAULT ANY_INSTANCE,
force IN BOOLEAN DEFAULT FALSE);
Use the parameters instance and force to control job and instance affinity. The default value of instance is 0 (zero) to indicate that any instance can execute the job. To run the job on a certain instance, specify the instance value. Oracle displays error ORA-23319 if the instance value is a negative number or NULL.

The force parameter defaults to false. If force is TRUE, any positive integer is acceptable as the job instance. If force is FALSE, the specified instance must be running, or Oracle displays error number ORA-23428.

DBMS_JOB.INSTANCE
To assign a particular instance to execute a job, use the following syntax:

DBMS_JOB.INSTANCE( JOB IN BINARY_INTEGER,
instance IN BINARY_INTEGER,
force IN BOOLEAN DEFAULT FALSE);
The FORCE parameter in this example defaults to FALSE. If the instance value is 0 (zero), job affinity is altered and any available instance can execute the job despite the value of force. If the INSTANCE value is positive and the FORCE parameter is FALSE, job affinity is altered only if the specified instance is running, or Oracle displays error ORA-23428.

If the force parameter is TRUE, any positive integer is acceptable as the job instance and the job affinity is altered. Oracle displays error ORA-23319 if the instance value is negative or NULL.

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