Table compression was first introduced in Oracle 9i as a space saver feature only for data warehousing projects. In oracle 11g , this is acceptable as mainstream feature which is acceptable for OLTP Databases. This will result in saving storage space as this will compress the table, increased I/O performance and reduced memory use in the buffer cache. Definitely, this incurs CPU overhead because of compression.
Compression can be done at the tablespace, table or partition level . Options/Features which are available with Compression :
