Oracle 11G OCP 1Z0-053 96

（96）Examine the following command:

SQL>ALTER TABLE booking SHRINK SPACE COMPACT;

Which activity is performed when the preceding command is executed?

A. The shrink operation touches every block in the BOOKING table

B. The high-water mark(HWM)for the BOOKING table is shifted from its original position

C. The progress of the shrink operation is saved in the bitmap blocks of the BOOKING table

D. The data manipulation language(DML)triggers on the BOOKING table are executed because the shrink operation is internally handled by the INSERT/DELETE operation

答案：（C）

解析：

ALTER TABLE...SHRINK SPACE COMPACT

COMPACT, Oracle只是defragment段空間並壓縮錶行.資料庫並不調整HWM,也不立即釋放空間.

                需要後面再執行另一個ALTER TABLE...SHRINK SPCACE語句來釋放空間.

                該選項用於以2個短的步驟而不是一個長的步驟來完成shrink操作.

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/17013648/viewspace-1252860/，如需轉載，請註明出處，否則將追究法律責任。