Index Compression with DB2 9 for z/OS

Overview

In data warehouse applications, it is common to have many very large indexes defined on large tables. It is also possible that the index spaces exceed the size of the tables upon which the indexes are based. As one way of helping to manage the cost of ownership, in DB2 9 for z/OS (New Function Mode) one can choose to compress indexes and can define indexes with a page size larger than 4 KB. Compression has been available for table spaces on z/OS since DB2 Version 3. This paper explains some of the significant differences between data and indexes in the way that compression is managed, as well as a comparison of the performance characteristics.