638.Which three statements are true about persistent configuration? (Choose three.)
A. A user cannot set privileges on the persistent lightweight jobs
B. Persistent lightweight jobs generate a large amount of metadata
C. It is possible to create fully self-contained persistent lightweight jobs
D. The use of a template is mandatory to create persistent lightweight jobs
E. Persistent lightweight jobs are useful when users need to create a large number of jobs in a short time
Answer: ADE


lightweight job产生很少的metadata.

轻量级作业有几个缺点：

1. 无法设置轻量级作业的权限；

2. 作业的权限从模板的计划.继承而来；

3. 由于轻量级作业使用模板，无法创建完全独立的轻量级作业，我们必须使用PL/SQL命令创建轻量级作业，而无法用过EM创建。

Lightweight Jobs

Use lightweight jobs when you have many short-duration jobs that run frequently. Under certain circumstances, using lightweight jobs can deliver a small performance gain.

Lightweight jobs have the following characteristics:

• Unlike regular jobs, they are not schema objects.

• They have a significant improvement in create and drop time over regular jobs because they do not have the overhead of creating a schema object.

• They have lower average session creation time than regular jobs.

• They have a small footprint on disk for job metadata and runtime data.

You designate a lightweight job by setting the job_style job attribute to 'LIGHTWEIGHT'. The other job style is 'REGULAR', which is the default.

Like programs and schedules, regular jobs are schema objects. In releases before Oracle Database 11g Release 1, regular jobs were the only job style supported by the Scheduler.

A regular job offers the maximum flexibility but does entail some overhead when it is created or dropped. The user has fine-grained control of the privileges on the job, and the job can have as its action a program or a stored procedure owned by another user.

If a relatively small number of jobs that run infrequently need to be created, then regular jobs are preferred over lightweight jobs.

A lightweight job must reference a program object (program) to specify a job action. The program must be already enabled when the lightweight job is created, and the program type must be either 'PLSQL_BLOCK' or 'STORED_PROCEDURE'. Because lightweight jobs are not schema objects, you cannot grant privileges on them. A lightweight job inherits privileges from its specified program. Thus, any user who has a certain set of privileges on the program has corresponding privileges on the lightweight job.

https://docs.oracle.com/cd/B28359_01/server.111/b28310/schedover004.htm#BGBJGHBH

参考：http://blog.itpub.net/17013648/viewspace-1330590/