Data compression feature in Oracle 11g has a couple of benefits. The obvious one is that it saves disk space so that the storage is less. The more appealing benefit of data compression though is that the data can be fetched using less physical I/O. If you look at the key benefits in this document from Oracle:
As per this document, the CPU overhead for the compression and de-compression of the data will be minimal. Think about the elimination of costs as you can compress the auditing data easily – this is specifically true for financial sector, food sector and banking applications where the data needs to be stored for a long period of time for compliance and this can be reported on when needed. In the days to come, as we play with this new feature, we will post our findings on the blog.