48 DBMS_JOB

Using DBMS_JOB

• Security Model

• Operational Notes

Security Model

No specific system privileges are required to use DBMS_JOB. No system privileges are available to manage DBMS_JOB. Jobs cannot be altered or deleted other than jobs owned by the user. This is true for all users including those users granted DBA privileges.

You can execute procedures that are owned by the user or for which the user is explicitly granted EXECUTE. However, procedures for which the user is granted the execute privilege through roles cannot be executed.

Note that, once a job is started and running, there is no easy way to stop the job.

Operational Notes

• Working with Real Application Clusters

• Stopping a Job

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.

DBMS_JOB.CHANGE

To alter user-definable parameters associated with a job, use the following syntax:

DBMS_JOB.CHANGE(  JOB IN BINARY_INTEGER,
      what                  IN VARCHAR2 DEFAULT NULL,
   next_date             IN DATE DEFAULT NULL,
   interval              IN VARCHAR2 DEFAULT NULL,
   instance              IN BINARY_INTEGER DEFAULT NULL,
   force                 IN BOOLEAN DEFAULT FALSE );

Two parameters, instance and force, appear in this example. The default value of instance is null indicating that job affinity will not change.

The default value of force is FALSE. Oracle displays error ORA-23428 if the specified instance is not running and error ORA-23319 if the instance number is negative.

DBMS_JOB.RUN

The force parameter for DBMS_JOB.RUN defaults to FALSE. If force is TRUE, instance affinity is irrelevant for running jobs in the foreground process. If force is FALSE, the job can run in the foreground only in the specified instance. Oracle displays error ORA-23428 if force is FALSE and the connected instance is the incorrect instance.

DBMS_JOB.RUN( 
      job    IN BINARY_INTEGER,
      force  IN BOOLEAN DEFAULT FALSE);

Stopping a Job

Note that, once a job is started and running, there is no easy way to stop the job.

Summary of DBMS_JOB Subprograms

BROKEN Procedure

This procedure sets the broken flag. Broken jobs are never run.

Syntax

DBMS_JOB.BROKEN ( 
   job       IN  BINARY_INTEGER,
   broken    IN  BOOLEAN,
   next_date IN  DATE DEFAULT SYSDATE);

Parameters

Usage Notes

You must issue a COMMIT statement immediately after the statement.

CHANGE Procedure

This procedure changes any of the fields a user can set in a job.

Syntax

DBMS_JOB.CHANGE ( 
   job       IN  BINARY_INTEGER,
   what      IN  VARCHAR2,
   next_date IN  DATE,
   interval  IN  VARCHAR2,
   instance  IN  BINARY_INTEGER DEFAULT NULL,
   force     IN  BOOLEAN DEFAULT FALSE);

Parameters

Usage Notes

• You must issue a COMMIT statement immediately after the statement.

• The parameters instance and force are added for job queue affinity. Job queue affinity gives users the ability to indicate whether a particular instance or any instance can run a submitted job.

• If the parameters what, next_date, or interval are NULL, then leave that value as it is.

Example

BEGIN
   DBMS_JOB.CHANGE(14144, null, null, 'sysdate+3');
   COMMIT;
END; 

INSTANCE Procedure

This procedure changes job instance affinity.

Syntax

DBMS_JOB.INSTANCE ( 
   job        IN BINARY_INTEGER,
   instance   IN BINARY_INTEGER,
   force      IN BOOLEAN DEFAULT FALSE);

Parameters

Usage Notes

You must issue a COMMIT statement immediately after the statement.

INTERVAL Procedure

This procedure changes how often a job runs.

Syntax

DBMS_JOB.INTERVAL ( 
   job       IN  BINARY_INTEGER,
   interval  IN  VARCHAR2);

Parameters

Usage Notes

• If the job completes successfully, then this new date is placed in next_date. interval is evaluated by plugging it into the statement select interval into next_date from dual;

• The interval parameter must evaluate to a time in the future. Legal intervals include:

  Interval	Description
  'sysdate + 7'	Run once a week.
  'next_day(sysdate,''TUESDAY'')'	Run once every Tuesday.
  'null'	Run only once.

  
  

• If interval evaluates to NULL and if a job completes successfully, then the job is automatically deleted from the queue.

• You must issue a COMMIT statement immediately after the statement.

NEXT_DATE Procedure

This procedure changes when an existing job next runs.

Syntax

DBMS_JOB.NEXT_DATE ( 
   job       IN  BINARY_INTEGER,
   next_date IN  DATE);

Parameters

Usage Notes

You must issue a COMMIT statement immediately after the statement.

REMOVE Procedure

This procedure removes an existing job from the job queue. This currently does not stop a running job.

Syntax

DBMS_JOB.REMOVE ( 
   job       IN  BINARY_INTEGER );

Parameters

Usage Notes

You must issue a COMMIT statement immediately after the statement.

Example

BEGIN
   DBMS_JOB.REMOVE(14144);
   COMMIT;
END; 

RUN Procedure

This procedure runs job JOB now. It runs it even if it is broken.

Running the job recomputes next_date. See view user_jobs.

Syntax

DBMS_JOB.RUN ( 
   job       IN  BINARY_INTEGER,
   force     IN  BOOLEAN DEFAULT FALSE);

Parameters

Example

EXECUTE DBMS_JOB.RUN(14144);

Exceptions

An exception is raised if force is FALSE, and if the connected instance is the wrong one.

SUBMIT Procedure

This procedure submits a new job. It chooses the job from the sequence sys.jobseq.

Syntax

DBMS_JOB.SUBMIT ( 
   job       OUT BINARY_INTEGER,
   what      IN  VARCHAR2,
   next_date IN  DATE DEFAULT sysdate,
   interval  IN  VARCHAR2 DEFAULT 'null',
   no_parse  IN  BOOLEAN DEFAULT FALSE,
   instance  IN  BINARY_INTEGER DEFAULT any_instance,
   force     IN  BOOLEAN DEFAULT FALSE);

Parameters

Usage Notes

• You must issue a COMMIT statement immediately after the statement.

• The parameters instance and force are added for job queue affinity. Job queue affinity gives users the ability to indicate whether a particular instance or any instance can run a submitted job.

Example

This submits a new job to the job queue. The job calls the procedure DBMS_DDL.ANALYZE_OBJECT to generate optimizer statistics for the table DQUON.ACCOUNTS. The statistics are based on a sample of half the rows of the ACCOUNTS table. The job is run every 24 hours:

VARIABLE jobno number;
BEGIN
   DBMS_JOB.SUBMIT(:jobno, 
      'dbms_ddl.analyze_object(''TABLE'',
      ''DQUON'', ''ACCOUNTS'', 
      ''ESTIMATE'', NULL, 50);' 
      SYSDATE, 'SYSDATE + 1');
   COMMIT;
END;
/
Statement processed.
print jobno
JOBNO
----------
14144

USER_EXPORT Procedures

There are two overloaded procedures. The first produces the text of a call to re-create the given job. The second alters instance affinity (8i and after) and preserves the compatibility.

Syntax

DBMS_JOB.USER_EXPORT ( 
   job    IN     BINARY_INTEGER,
   mycall IN OUT VARCHAR2);

DBMS_JOB.USER_EXPORT ( 
   job      IN     BINARY_INTEGER,
   mycall   IN OUT VARCHAR2,
   myinst   IN OUT VARCHAR2);

Parameters

WHAT Procedure

This procedure changes what an existing job does, and replaces its environment.

Syntax

DBMS_JOB.WHAT ( 
   job       IN  BINARY_INTEGER,
   what      IN  VARCHAR2);

Parameters

Usage Notes

• You must issue a COMMIT statement immediately after the statement.

• Some legal values of what (assuming the routines exist) are:

  • 'myproc(''10-JAN-82'', next_date, broken);'

  • 'scott.emppackage.give_raise(''JENKINS'', 30000.00);'

  • 'dbms_job.remove(job);'