View the Exhibits exhibit1 and exhibit2.
Both the processes use PROG_1 as the job template that is already available. The time taken by the jobs are recorded in the TEST_LOG table. While comparing the time taken to create the jobs, the process in exhibit1 takes less time than the process in exhibit2.
What is the reason for this?
Exhibit 
A. It updates several tables in the SYSTEM tablespace instead of creating new tables.
B. It creates jobs temporarily in memory only.
C. It creates less metadata for the jobs.
D. It writes the job metadata to disk in compressed format.
可以看到这个存储过程使用循环用 PROG_1 模板创建了很多 job，但是图示1中job_style=>'lightweight'
可知，使用的是 lightweight 轻量级的 job。图示 2 中使用的是 REGULAR 常规的 job
可以对照 638 题。
轻量级作业有如下的特点：
1.和普通的 job 不同，它们没有方案对象。
2.由于没有方案对象，它们在创建和删除的时候对于一般的 job 有性能提升。
3.它们有更低的平均会话时间
4.他们在磁盘上有一个很小的痕迹来存放 job 元数据和运行数据