OCP 1Z0 052 149

149. You executed the following command to create a tablespace called SALES_DATA:

SQL> CREATE TABLESPACE sales_data DATAFILE SIZE 100M

SEGMENT SPACE MANAGEMENT AUTO;

Which two statements are true about the SALES_DATA tablespace? (Choose two.)

A.The database automatically determines the extent-sizing policy for the tablespace.

B.The segments are automatically shrunk when the contents are removed from them.

C.The allocation of extents within the tablespace is
managed through the dictionary tables.

D.The space utilization description of the data blocks in segments is recorded in bitmap blocks.

E.The space utilization description of the data blocks in segments is managed through
free lists.

Answer: AD

回收表空间一般需要dba在业务不忙的时候手动作。如果自动shrink，那够吓人的。

allocation of extents分为字典管理与本地管理。而本地管理：

In a locally managed tablespace, there are two methods that Oracle Database can use to manage segment space: automatic and manual.

此处建的就是本地管理中的automatic 。

Manual segment space management uses linked lists called "freelists" to manage free space in the segment, while automatic segment space management uses bitmaps.