DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

Regression is about 5% better than non-data sharing. V8 can achieve significant
performance improvements over V7 primarily due to some data sharing specific
enhancements such as CF Request Batching and protocol 2. See Chapter 8, “Data
sharing enhancements” on page 319 for more details.
► -20 to +15% regression in batch DRDA workloads
These huge gains over V7 are primarily due to API reduction for multi-row fetch in a
distributed environment. See Chapter 7, “Networking and e-business” on page 281 for
more details.
► -5% to +10% regression for utilities
See Chapter 6, “Utilities” on page 261 for details.
► -20% to +15% regression for query workloads
Simple and short queries tend to increase in CPU while long running queries tend to
decrease in CPU. However, the gains in performance can be quite substantial. They are
primarily due to access path enhancements in V8. See Chapter 3, “SQL performance” on
page 29 for more details.
Now, let us have a brief overview of DB2 utilities, where we found a wide variety of results.
Figure 4-2 summarizes these results. Once again, a ‘+’ means a CPU increase and a ‘-’
means a CPU decrease.
reorg index
check index
recover tablespace
unload
online reorg
Figure 4-2 V7 vs. V8 Utility CPU measurements
All these utilities were executed with no new V8 function, except where the defaults changed
from V7 to V8. We saw that:
► LOAD achieved a 2% reduction in CPU
► REORG achieved a 2% increase in CPU
► REBUILD INDEX varied from a 9% reduction, to a 13% increase in CPU
► RUNSTATS varied from a huge 45% reduction, to a 7% increase in CPU
132 DB2 UDB for z/OS Version 8 Performance Topics
V7 vs. V8 Utility CPU measurements
load
reorg
rebuild index
runstats
copy
-40%
-20%
0% +20%