Partitioned tables can have indexes that are nonpartitioned (existing in a single table space within a database partition), indexes that are themselves partitioned across one or more table spaces within a database partition, or a combination of the two.
Partitioned indexes offer benefits when performing roll-in operations with partitioned tables (in other words, attaching a data partition to another table using the ATTACH PARTITION clause on the ALTER table statement.) With a partitioned index, you can avoid the index maintenance that you would otherwise have to perform with nonpartitioned indexes. When a partitioned table uses a nonpartitioned index. you must use SET INTEGRITY statement to perform index maintenance on the newly combined data partitions. Not only is this time consuming, it also can require a large amount of log space, depending on the number of rows being rolled in.
Starting in DB2® Version 9.7 Fix Pack 1, you can create an index over XML data on a partitioned table as either partitioned or nonpartitioned. The default is a partitioned index. Unique indexes over XML data are always nonpartitioned.