1z1-067 全真模擬試験 DEMO

問題10: You want to reduce fragmentation and reclaim unused space for the sales table but not its
dependent objects.
During this operation, you want to ensure the following:
i.Long-running queries are not affected.
ii.No extra space is used.
iii.Data manipulation language (DML) operations on the table succeed at all times throughout the
process.
iv.Unused space is reclaimed both above and below the high water mark.
Which alter TABLE option would you recommend?
A. ROW STORE COMPRESS BASIC
B. SHRINK SPACE COMPACT
C. SHRINK SPACE CASCADE
D. DEALLOCATE UNUSED
正解: B
Explanation
The COMPACT clause lets you divide the shrink segment operation into two phases. When you
specify COMPACT, Oracle Database defragments the segment space and compacts the table rows but
postpones the resetting of the high water mark and the deallocation of the space until a future time.
This option is useful if you have long-running queries that might span the operation and attempt to
read from blocks that have been reclaimed. The defragmentation and compaction results are saved
to disk, so the data movement does not have to be redone during the second phase. You can reissue
the SHRINK SPACE clause without the COMPACT clause during off-peak hours to complete the second
phase.
References:
https://docs.oracle.com/cd/B28359_01/server.111/b28310/schema003.htm