DB2 Performance features in DB2 V9 for z/OS – Part 12

Happy Holidays – Three Cheers for Online Reorgs!

Given the snowstorm and the extra time in airports, I thought it was perfect time to do a blog entry.  In the early releases of DB2, we had to work the holidays to do the Reorgs because that was the only time during the year when we weren’t taking orders.  Now with online Reorgs and the elimination of DB2 BUILD2 index rebuilding phase everyone can have a Happy Holiday.

In DB2 Version 9, the reorganization utility BUILD2 phase that rebuilds your non-partitioning indexes (NPIS) was eliminated through improvements within DB2.  This elimination of the BUILD2 phase is very important since this phase took the associated tablespace and its other indexes offline causing downtime from database access.

Be warned that the online Reorg does not come free of charge. Eliminating the BUILD2 phase provides a dramatic improvement in availability, but can increase the utility CPU time and the elapsed time. Behind the scenes, DB2 is using a lot of active and archive logs, CPU and I/O resources to provide access while the database rebuilds the indexes.  Make sure the activity is at the complete minimum possible before starting an online Reorg.  Eliminating the Reorg utility BUILD2 phase allow online Reorgs during non-peak processing and provides the DBAs with more opportunity to maintain and improve their systems, database and application performance.

So have a Happy Holidays everyone and leave the Reorgs for some other time of the year.

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