Which statements are true regarding table compression? (Choose all that apply.)
A.
It requires uncompress operation during I/O.
B.
It saves disk space and reduces memory usage.
C.
It saves disk space but has no effect on memory usage.
D.
It incurs extra CPU overhead during DML but not direct loading operations.
E.
It incurs extra CPU overhead during DML as well as direct loading operations.
The answer E is wrong.
Oracle says:
“The clause “compress for all operations” enables compression on all DML activities like INSERT, UPDATE, etc. The compression occurs on all DML activities; not just direct path inserts as in the previous versions.”
Answer D is correct.
Answer E is right, I believe moguKiller misunderstood what was written.
Oracle says: “There is, however, a cost in CPU overhead for data loading and DML.”.
Source: http://docs.oracle.com/cd/B28359_01/server.111/b28310/tables002.htm