agburke 060001QPDN Visits (1910)
I wanted to remind everyone that there is a very comprehensive website in developerworks that lists best practices for many topics from LOBs, to Utilities, to stored procedures.
The content includes downloadable presentations as well as pre-recorded webcasts so that you can walk through the slides as the moderator is presenting.
Here is the URL and a screen shot of the Monitoring and Tuning port
Michael_D. 1100004WAH Visits (2650)
DB2 10 can reduce the total DB2 CPU demand from 5-20% when you take advantage of all the enhancements. Many CPU reductions are built in directly to DB2, requiring no application changes. Some enhancements are implemented through normal DB2 activities through rebinding, restructuring database definitions, improving applications, and utility processing. The CPU demand reduction features have the potential to provide significant total cost of ownership savings based on the application mix and transaction types.
Improvements in optimization reduce costs by processing SQL automatically with more efficient data access paths. Improvements through a range-list index scan access method, list prefetch for IN-list, more parallelism for select and index insert processing, better work file usage, better record identifier (RID) pool overflow management, improved sequential detection, faster log I/O, access path certainty evaluation for static SQL, and improved distributed data facility (DDF) transaction flow all provide more efficiency without changes to applications. These enhancements can reduce total CPU enterprise costs because of improved efficiency in the DB2 10 for z/OS.
DB2 10 includes numerous performance enhancements for Large Objects (LOBs) that save disk space for small LOBs and that provide dramatically better performance for LOB retrieval, inserts, load, and import/export using DB2 utilities. DB210 can also more effectively REORG partitions that contain LOBs.
This IBM Redbooks® publication® provides an overview of the performance impact of DB2 10 for z/OS discussing the overall performance and possible impacts when moving from version to version. We include performance measurements that were made in the laboratory and provide some estimates.
Keep in mind that your results are likely to vary, as the conditions and work will differ.
In this book, we assume that you are somewhat familiar with DB2 10 for z/OS.
See DB2 10 for z/OS Technical Overview, SG24-7892-00, for an introduction to the new functions.
Michael_D. 1100004WAH Visits (2355)
Higher CF CPU utilization in a DB2 10 for z/OS data sharing environment during Delete_Name processing. Delete_Name requests/sec can be significantly higher in DB2 10 for z/OS than in DB2 9 for z/OS. In V10, when the pageset/partition becomes non GBP dependent, the Delete_Name process deletes only data entries to avoid cross invalidation processing at that time, and to allow cleanup of the directory
entries later when other pages are registered. The V9 Delete_Name process deleted both data and directory entries. In DB2 10 for z/OS, the Delete_Name requests/sec can be significantly higher because CFCC processing is not as efficient when only data entries are deleted.
PM51467: CF DELETE_NAME PERFORMANCE IN DB2 10 FOR Z/OS http
Michael_D. 1100004WAH Visits (7326)
PM56845: PROVIDE OPTION FOR OPTIMIZE FOR 1 ROW TO ALLOW SOME SORT ACCESS PATHhtt
In all versions of DB2, the OPTIMIZE FOR 1 ROW clause requests DB2 to choose an access path that avoids a sort. In DB2 versions prior to 10, there is a possibility to obtain an access path with a sort even though that path is strongly discouraged. In DB2 10, DB2 will not compete access paths with sorts and will instead choose the lowest cost access path that does not require a sort.
This APAR provides an option to return to the previous version OPTIMIZE FOR 1 ROW behavior. As such, it does not eliminate the risk of an inefficient access path being chosen with OPTIMIZE FOR 1 ROW when the efficient access requires a sort. However, it does limit that exposure to what already existed in DB2 prior to DB2 10.
For queries that need sorts, the recommended solution is to avoid coding the OPTIMIZE FOR 1 ROW clause. Without the OPTIMIZE FOR 1 ROW clause, DB2 will choose access paths based on cost and will not make an effort to avoid sorts.
Local work around:
For queries that need sorts for efficient access, the solution is to avoid coding the OPTIMIZE FOR 1 ROW clause.
Change application to code OPTIMIZE FOR 2 ROWS
Wait for APAR PM56845 that is now open to provide option for OPTIMIZE FOR 1 ROW to allow sort access plans
Michael_D. 1100004WAH Visits (4345)
Michael_D. 1100004WAH Visits (3283)
End of Service Announcement DB2 9 for z/OS - June 27, 2014
On February 7, 2012, IBM announced the End of Service (EOS) for DB2 9 for z/OS. The effective EOS date is June 27, 2014.
For your convenience, here is a link to the announcement letter:
Michael_D. 1100004WAH Visits (1846)
DB2 9, which GA'd back in March 2007, is replaced by DB2 10 for z/OS (5605-DB2). For further information, please refer to the announcement letters accessible via these links: