IBM Tivoli Monitoring > Version 6.3 Fix Pack 2 > Installation Guides > Installation Guide > Performance tuning > Tivoli Data Warehouse > Relational database design and performance tuning for DB2 Database servers > Database design details > Database maintenance
IBM Tivoli Monitoring, Version 6.3 Fix Pack 2
REORG
After many INSERT, DELETE, and UPDATE changes to table data, often involving variable length columns activity, the logically sequential data might be on non-sequential physical data pages. The database manager must perform additional read operations to access data. You can use the REORG command to reorganize DB2 tables, eliminating fragmentation and reclaiming space.
Regularly scheduled REORGs improve I/O and significantly reduce elapsed time. Implement a regularly scheduled maintenance plan.
DB2 provides the following types of REORG operation, classic REORG and In-Place REORG. If you have an established database maintenance window, use the classic REORG. If you operate a 24 by 7 operation, use the In-Place REORG.
- Classic REORG
- The fastest method of REORG
- Indexes rebuilt during the reorganization
- Ensures perfectly ordered data
- Access limited to read-only during the UNLOAD phase, with no access during other phases
- Not restartable
- In-Place REORG
- Slower than the Classic REORG and takes more time to complete
- Does not ensure perfectly ordered data or indexes
- Requires more log space
- Can be paused and restart
- Can allow applications to access the database during reorganization
Parent topic:
Database maintenance