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Oracle OCP 1Z0-050（21题）解析

QUESTION 21:

Which statement describes the information returned by the DBMS_SPACE.SPACE_USAGE procedure for LOB space usage?

A. It returns space usage of only SecureFile LOB chunks.

B. It returns space usage of only BasicFile LOB chunks.

C. It returns both BasicFile and SecureFile LOB space usage for both partitioned and nonpartitioned tables.

D. It returns both BasicFile and SecureFile LOB space usage for only nonpartitioned tables.

正确答案：A

解析：

需要阅读Oracle官方文档。

Oracle官方文档的解释：

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 PARTITIONSand 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.

DBMS_SPACE.SPACE_USAGE(   segment_owner           IN  VARCHAR2,   segment_name            IN  VARCHAR2,   segment_type            IN  VARCHAR2,   unformatted_blocks      OUT NUMBER,   unformatted_bytes       OUT NUMBER,   fs1_blocks              OUT NUMBER,   fs1_bytes               OUT NUMBER,   fs2_blocks              OUT NUMBER,   fs2_bytes               OUT NUMBER,   fs3_blocks              OUT NUMBER,   fs3_bytes               OUT NUMBER,   fs4_blocks              OUT NUMBER,   fs4_bytes               OUT NUMBER,   full_blocks             OUT NUMBER,   full_bytes              OUT NUMBER,   partition_name          IN  VARCHAR2 DEFAULT NULL);

DBMS_SPACE.SPACE_USAGE(   segment_owner           IN    VARCHAR2,   segment_name            IN    VARCHAR2,   segment_type            IN    VARCHAR2,   segment_size_blocks     OUT   NUMBER,   segment_size_bytes      OUT   NUMBER,   used_blocks             OUT   NUMBER,   used_bytes              OUT   NUMBER,   expired_blocks          OUT   NUMBER,   expired_bytes           OUT   NUMBER,   unexpired_blocks        OUT   NUMBER,   unexpired_bytes         OUT   NUMBER,   partition_name          IN    VARCHAR2 DEFAULT NULL);

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