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

100 Inserts activated trigger 100 times
SQL DML TOTAL
-------- --------
SELECT 0
INSERT 100
UPDATE 100
DELETE 0
DESCRIBE 100
DESC.TBL 0
PREPARE 100
OPEN 0
FETCH 0
CLOSE 0
DML-ALL 401
Figure 3-39 SQL and BPOOL activity - Trigger 100 times
The execution of 100 inserts activates the trigger 100 times executing update. With DB2 V7,
the buffer pool BP1 used by the work files indicates 600 getpages and 400 buffer updates. In
DB2 V8 there was no activity related to work files.
Figure 3-40 compares the CPU times when executing triggers in V7 and V8.
CPU time - lower is better
Figure 3-40 CPU time when invoking the trigger 100 times
The figure shows that the CPU used for non-nested (everything that is not in the trigger) was
reduced by 8.0% and the CPU to execute the trigger was reduced by 5.5%.
Generally a larger improvement can be anticipated by avoiding work files. In this case, such
improvement is partially offset by the increase in CPU usage by going to V8.
88 DB2 UDB for z/OS Version 8 Performance Topics
DB2 V7 - workfile activity
BP1 BPOOL ACTIVITY TOTAL
--------------------- --------
BPOOL HIT RATIO (%) 100
GETPAGES 600
GETPAGES-FAILED 0
BUFFER UPDATES 400
SYNCHRONOUS WRITE 0
SYNCHRONOUS READ 0
SEQ. PREFETCH REQS 100
LIST PREFETCH REQS 0
DYN. PREFETCH REQS 0
PAGES READ ASYNCHR. 0
100 Inserts activated Trigger 100 times
0.02
0.015
0.01
0.005
0
-8.0%
-5.5%
CPU non-nested CPU trigger
DB2 V8 - workfile activity
BP1 no use reported
DB2 V7
DB2 V8