（43）In your database instance, the STATISTICS_LEVEL initialization parameter is set to BASIC. What is the impact of this setting?

A.Optimizer statistics are collected automatically.

B.Only timed operating system (OS) statistics and plan execution statistics are collected.

C.The snapshots for the Automatic Workload Repository (AWR) are not generated automatically.

D.Snapshots cannot be collected manually by using the DBMS_WORKLOAD_REPOSITORY package.

E.The Oracle server dynamically generates the necessary statistics on tables as part of query optimization.

答案：（C）

解析：

参考《References》中STATISTICS_LEVEL初始化参数

STATISTICS_LEVEL = BASIC会禁用许多重要的统计信息的收集：

1. AWR快照

2. ADDM

3. 所有server-generated预警

4. 自动SGA内存管理

5. 对象层次的统计信息

6. 端到端的应用程序跟踪（v$CLIENT_STATS)

7. 数据库时间分布统计（V$SESS_TIME_MODEL和V$SYS_TIME_MODEL）

8. 服务层次的统计

9. Buffer cache advisor

10. MTTR advisor

11. Shared Pool size advisor

12. 段层次的统计信息

13. PGA Target advisor

14. Timed statistics

15. 统计的监控

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Oracle 11G OCP 1Z0-052 43