2.You plan to have a larger moving window size(移動視窗大小) for the default system-defined moving window baseline because you want to use the adaptive threshold.

你計劃增加的移動視窗大小(AWR保留時間必須比他大，dba_hist_wr_control檢視awr配置；dba_hist_baseline可以檢視移動視窗)

Which statement factors(要素) in this consideration(考慮) while increasing the size of the moving window.?

當增加移動視窗時，需要考慮哪個要素？

A. The collection level for the AWR should be set to BASIC.

AWR配置引數：

BASIC：AWR統計資訊的關閉，只收集少量的資料庫統計資訊。

TYPICAL：預設值，只有部分的統計收集，都是需要監控oracle資料庫的典型行為。

ALL：所有可能的統計都被捕捉，並且有作業系統的一些資訊，這個級別的捕捉用的較少，比如要更多的sql診斷資訊。

B. The moving window size must be less than Undo Retention.

C. The moving window size should be greater than the Automatic Workload Repository (AWR) retention period.

D. The moving window size should be equal to or less than the Automatic Workload Repository (AWR) retention period.

答案：D  比AWR要小。