Database compression

Despite the fact that computer memory costs have decreased dramatically over the past few years, data storage still remains, and will probably always remain, an important cost factor for many large scale database applications. Compressing data in a database system is attractive for two reasons: data storage reduction and performance improvement. Storage reduction is a direct and obvious benefit, while performance improves because smaller amounts of physical data need to be moved for any particular operation on the database. We address several aspects of reversible data compression and compression techniques:general concepts of data compression; a number of compression techniques; a comparison of the effects of compression on common data types; advantages and disadvantages of compressing data; and future research needs.