Hitachi recommends using the inner replica facility because you can reference and update the database while reorganizing it. This is called updatable online reorganization. If the inner replica facility is not used, the database cannot be referenced or updated while it is being reorganized. Using the inner replica facility minimizes the impact on online job tasks because job processing uses the replica database while the master database is being reorganized. Figure D-2 shows how a database is reorganized using the inner replica facility.
Figure D-2 Database reorganization using the inner replica facility
![[Figure]](figure/zu0d0020.gif)
- Explanation
- The database reorganization utility (prdorg command) is used to reorganize the master database, and the replica database is used for the online job tasks.
- Before reorganizing the current database, another database is committed and the current database is switched to that database. The current database cannot be referenced or updated during this time. After the current database is switched, the master database is reorganized and the replica database is used for performing online job tasks. After reorganization is complete, the system log for the replica database becomes input information and the update processes performed during the reorganization are applied to the master database. This is called reflection processing.
For details about the inner replica facility, see the manual HiRDB Staticizer Option Version 7 Description and User's Guide.
- When the inner replica facility is not used
- When the inner replica facility is not used, Hitachi recommends using the pdhold command to place RDAREAs storing a reorganization table in hold status so UAPs do not wait for lock-release. This is because EX (the update mode) locks the table during reorganization. UAPs that were accessing in the reorganization table are terminated immediately without waiting for lock-release because RDAREAs in hold status cannot be accessed. Set in the reorganization table the amount of time RDAREAs will not be accessible, and. reorganize the table within that amount of time.