It's clear that 11g data compression offers these huge benefits, but the exact overhead costs remain unknown:

• Up to a 3x disk savings - Depending on the nature of your data, Oracle compression will result in huge savings on disk space.

• Cheaper solid-state disk - Because compressed tables reside on fewer disk blocks, shops that might not otherwise be able to afford Oracle flash disks can now enjoy I/O speeds up to 300x faster than platter disk.

• Faster full scan/range scan operations - Because tables will reside on less data blocks, full table scans and index range scans can retrieve the rows with less disk I/O.
  

• Reduced network traffic - Because the data blocks are compressed/decompressed only within Oracle, the external network packets will be significantly smaller.