Which statements are true regarding table compression? (Choose all that apply.)
A.
It saves disk space and reduces memory usage.
B.
It saves disk space but has no effect on memory usage.
C.
It incurs extra CPU overhead during DML as well as direct loading operations.
D.
It incurs extra CPU overhead during DML but not direct loading operations.
E.
It requires uncompress operation during I/O.
Main advantages of this new compression feature is as following.
1) 2-4X reduction in storage.
2) Improved memory efficiency as data remains compressed in memory.
3) Minimal or no performance impact on DML operations.
4) Faster queries in many cases, due to improved I/O and memory
efficiency.
5) Better network bandwidth utilization.
6) Transparent to applications – no application changes required.
A slight disadvantage is that compression is CPU hungry.
with 11gR2 we have four types of compression at the table level.
1) Basic Compression
2) OLTP Compression
3) Warehouse compression (Hybrid Columnar Compression)
4) Online archival compression (Hybrid Columnar Compression)