27使用调度程序
Oracle Database provides database job capabilities through Oracle Scheduler (the Scheduler). This chapter explains how to use the various Scheduler components, and discusses the following topics:
调度程序对象和它们的命名
使用Jobs
使用Programs
使用Schedules
使用Job Classes
使用Windows
使用Window Groups
使用Events
使用Chains
分配资源通过jobs
Note:
This chapter describes how to use the DBMS_SCHEDULER package to work with Scheduler components. You can accomplish the same tasks using Oracle Enterprise Manager.
使用jobs
一个job是一个调度和一个程序的结合，还有额外的被程序要求的参数。这一部分给你介绍了基本的job任务和讨论下列主题：
Job任务和他们的存储过程
创建jobs
复制jobs
修改jobs
运行jobs
停止jobs
仍掉jobs
关闭jobs
开启jobs
See Also:
"Jobs" for an overview of jobs.
创建Jobs
你可以创建jobs使用CREATE_JOB存储过程或者EM.当创建一个job，你可以指定一个动作，一个schedule，和其他属性。例如，下列的语句创建了一个job叫做update_sales，调用了一个存储的存储过程在OPS模式中来更新一个sales概览表：
BEGIN
DBMS_SCHEDULER.CREATE_JOB (
job_name => 'update_sales',
job_type => 'STORED_PROCEDURE',
job_action => 'OPS.SALES_PKG.UPDATE_SALES_SUMMARY',
start_date => '28-APR-03 07.00.00 PM Australia/Sydney',
repeat_interval => 'FREQ=DAILY;INTERVAL=2', /* every other day */
end_date => '20-NOV-04 07.00.00 PM Australia/Sydney',
job_class => 'batch_update_jobs',
comments => 'My new job');
END;
/
你能创建一个job以另外一个schema通过指定schema.job_name.因此，一个job的创建者不一定是job的属主。Job的属主是job被创建的模式对应那个用户，job创建者时正在创建job的用户。Job被创建使用job被创建的schema的权限。Job运行时的NLS环境变量是job被创建那一时刻被呈现的NLS环境变量。
After a job is created, it can be queried using the *_SCHEDULER_JOBS views. Jobs are created disabled by default and need to be enabled to run.
Jobs are set to be automatically dropped by default after they complete. Setting the auto_drop attribute to FALSE causes the job to persist. Note that repeating jobs are not auto-dropped unless the job end date passes, the maximum number of runs (max_runs) is reached, or the maximum number of failures is reached (max_failures).
Ways of Creating Jobs
You create a job using the CREATE_JOB procedure or Enterprise Manager. Because this procedure is overloaded, there are several different ways of using it. In addition to inlining a job during the job creation, you can also create a job that points to a named program and schedule. This is discussed in the following sections:
- Creating Jobs Using a Named Program
- Creating Jobs Using a Named Schedule
- Creating Jobs Using a Named Program and Schedule
Creating Jobs Using a Named Program
You can also create a job by pointing to a named program instead of inlining its action. To create a job using a named program, you specify the value for program_name in the CREATE_JOB procedure when creating the job and do not specify the values for job_type, job_action, and number_of_arguments.
To use an existing program when creating a job, the owner of the job must be the owner of the program or have EXECUTE privileges on it. An example of using the CREATE_JOB procedure with a named program is the following statement, which creates a job called my_new_job1:
BEGIN
DBMS_SCHEDULER.CREATE_JOB (
job_name => 'my_new_job1',
program_name => 'my_saved_program',
repeat_interval => 'FREQ=DAILY;BYHOUR=12',
comments => 'Daily at noon');
END;
/
Creating Jobs Using a Named Schedule
You can also create a job by pointing to a named schedule instead of inlining its schedule. To create a job using a named schedule, you specify the value for schedule_name in the CREATE_JOB procedure when creating the job and do not specify the values for start_date, repeat_interval, and end_date.
You can use any named schedule to create a job because all schedules are created with access to PUBLIC. An example of using the CREATE_JOB procedure with a named schedule is the following statement, which creates a job called my_new_job2:
BEGIN
DBMS_SCHEDULER.CREATE_JOB (
job_name => 'my_new_job2',
job_type => 'PLSQL_BLOCK',
job_action => 'BEGIN SALES_PKG.UPDATE_SALES_SUMMARY; END;',
schedule_name => 'my_saved_schedule');
END;
/
Creating Jobs Using a Named Program and Schedule
A job can also be created by pointing to both a named program and schedule. An example of using the CREATE_JOB procedure with a named program and schedule is the following statement, which creates a new job called my_new_job3 based on the existing program my_saved_program1 and the existing schedule my_saved_schedule1:
BEGIN
DBMS_SCHEDULER.CREATE_JOB (
job_name => 'my_new_job3',
program_name => 'my_saved_program1',
schedule_name => 'my_saved_schedule1');
END;
/
Copying Jobs
You copy a job using the COPY_JOB procedure or Enterprise Manager. This call copies all the attributes of the old job to the new job except the new job is created disabled and has another name.
See Oracle Database PL/SQL Packages and Types Reference for detailed information about the COPY_JOB procedure.
Altering Jobs
You alter a job using the SET_ATTRIBUTE procedure or Enterprise Manager. All jobs can be altered, and, with the exception of the job name, all job attributes can be changed. If there is a running instance of the job when the SET_ATTRIBUTE call is made, it is not affected by the call. The change is only seen in future runs of the job.
In general, you should not alter a job that was automatically created for you by the database. Jobs that were created by the database have the column SYSTEM set to TRUE in job views. The attributes of a job are available in the *_SCHEDULER_JOBS views.
It is perfectly valid for running jobs to alter their own job attributes using the SET_ATTRIBUTE procedure, however, these changes will not be picked up until the next scheduled run of the job.
See Oracle Database PL/SQL Packages and Types Reference for detailed information about the SET_ATTRIBUTE procedure and "Configuring the Scheduler".