653.View the Exhibits: Exhibit 1 and Exhibit 2
Both processes use an existing job template PROG_1. The time taken by the jobs are recorded in the
TEST_LOG table. It was observed that the job creation process in exhibit 1 takes less time than in exhibit
2.
What is the reason for this?
Exhibit:
A.It creates less metadata for jobs
B.It creates jobs temporarily in memory only
C.It writes the jobs metadata to disk in compressed format
D.It updates tables in SYSTEM tablespace instead of creating new tables
Answer: A
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e25494/schedover.htm#ADMIN13368
从Exhibit #1中job_style=>'lightweight'可知，此作业是轻量型作业。
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 significantly better create and drop times over regular jobs because they do not have the overhead of creating a schema object.
-
They have lower average session create time than regular jobs.
-
They have a small footprint on disk for job metadata and run-time 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, the only job style supported by the Scheduler was regular.
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.