Continuous database operation and repeated data additions, updating, and deletions affect the arrangement of indexes and data in a database, resulting in reduced data storage efficiency and processing performance. You can repair the data and index arrangement by executing the database reorganization utility (pdrorg command). However, you must stop online services during execution of pdrorg because a table cannot be referenced or updated while it is being processed by the pdrorg command (except when the inner replica facility is used).

The free page release utility (pdreclaim) is able to release used free pages, which is an element of the reorganization processing executed by the pdrorg command, during online operation (The pdreclaim command executes pdrorg internally). Note that used free pages cannot be released when an application program that places the table in the lock mode (EX) is executing or when a utility is executing. Free segments can be released only when neither an application program nor a utility is accessing the subject RDAREA.

Use pdreclaim in the following cases:

• Database reorganization is not appropriate to the system's mode of operation because it is not feasible to stop online service.^#
• The database reorganization interval (operation cycle) needs to be increased without compromising storage efficiency.

#: For details about the limitations when database reorganization is not performed by pdreclaim, see 11.1.4 Difference in functions from pdrorg. If you cannot use pdreclaim due to the limitations, you must use the online reorganization function that combines pdrorg and the inner replica facility.