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

Class 1 CPU time (MSEC)
Multi-row Fetch support of DSNTIAUL
(10,000 rows fetched / test)
250
200
150
100
50
0
V7
Figure 9-4 Multi-row fetch support of DSNTIAUL
As shown on Figure 9-4, the default value for DSNTIAUL retrieves 100 rows per fetch. When
you retrieve 1000 or 10000 rows, the CPU time stays almost the same.
If you want to change the number of rows, the parameter can be specified together with the
SQL parameter, as shown in Example 9-1.
Example 9-1 DSNTIAUL with multi-row parameter
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB81) PARMS('SQL,250') -
LIB(’DSN810.RUNLIB.LOAD’)
...
//SYSIN DD *
LOCK TABLE DSN8810.PROJ IN SHARE MODE;
SELECT * FROM DSN8810.PROJ;
V8
Runs with different number of
rows in a FETCH call
V8
mr = 10 V8
mr = 100
V8 w/o MR : +20%
V8 with MR : -30% to -50%
V8
mr=1000 V8
mr=10000
5 columns
20 columns
In Figure 9-5, we compare the performance of DSNTIAUL running under V7 and V8 in terms
of CPU. Elapsed times are very similar.
Chapter 9. Installation and migration 349