053试题 9 - DBMS_SPACE.SPACE_USAGE ，securefiles

题目：

9.Which statement describes the information returned by the DBMS_SPACE.SPACE_USAGE procedure  for LOB space usage?
A. It returns space usage of only BasicFile LOB chunks.
B. It returns space usage of only SecureFile LOB chunks.
C. It returns both BasicFile and SecureFile LOB space usage for only nonpartitioned tables.
D. It returns both BasicFile and SecureFile LOB space usage for both partitioned and nonpartitioned tables.

参考答案 B  
解析
题目意思问，那个选项是正确的，关于使用DBMS_SPACE.SPACE_USAGE 存储过程对于lob字段，返回什么。
这个只返回securefile的block使用情况。所以选择B  。

 

参考文档：

https://docs.oracle.com/cd/E11882_01/appdev.112/e40758/d_space.htm#ARPLS68113

SPACE_USAGE Procedures

The first form of the procedure shows the space usage of data blocks under the segment High Water Mark. You can calculate usage for LOBs, LOB PARTITIONS and LOB SUBPARTITIONS. This procedure can only be used on tablespaces that are created with auto segment space management. The bitmap blocks, segment header, and extent map blocks are not accounted for by this procedure. Note that this overload cannot be used on SECUREFILE LOBs.

The second form of the procedure returns information about SECUREFILE LOB space usage. It will return the amount of space in blocks being used by all the SECUREFILE LOBs in the LOB segment. The procedure displays the space actively used by the LOB column, freed space that has retention expired, and freed space that has retention unexpired. Note that this overload can be used only on SECUREFILE LOBs.

END