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

7.2.2 Performance - Distributed client to Host
In this section we present the performance measurements in a distributed client to host
environment.
Performance measurement description
► DB2 for z/OS, V7 and V8
► z/OS Release 1.3
► IBM z900 Series 2064 2-way processor
► ESS 800 DASD (with FICON channel)
► DB2 Connect/client V8 acting as a DRDA application requester
Performance measurement results
DB2 for Multiplatforms V8 acting as client still does not support explicit multi-row FETCH
when accessing DB2 for z/OS V8. Multi-row fetch is supported when using dynamic scrollable
cursors in CLI coming from a distributed platform. However the client application and the DB2
for z/OS V8 server will benefit from the DB2 for z/OS V8 multi-row enhancement. By default
the DIST address space will issue multi-row FETCH requests to DBM1 for read-only cursors
with the rowset size determined by the query block size.
Figure 7-4 presents the result of a test case in which 100,000 20 column rows were fetched.
Class 1 time (seconds)
5
4
3
2
1
0
3.95
2.91
Figure 7-4 Multi-row fetch - DB2 client to host
Compared to DB2 V7, we notice a decrease in CPU at the DRDA application server of 53%
and a decrease in elapsed time of 26% at the client application due to the larger query block
size, up to 64 KB is supported by DB2 for z/OS V8.
The 64 KB query block size can reduce the network transfers by 50% in DB2 V8, compared to
DB2 V7.
In DB2 V8 performance of CLI/ODBC applications will benefit from array insert. If we compare
single row insert in DB2 V8 to single row in DB2 V7 elapsed time at the client increases with
290 DB2 UDB for z/OS Version 8 Performance Topics
Multi-row Fetch, Distributed (DB2 client to host)
Total rows fetched : 100,000
Client Elapsed time Server CPU Time
1.79
0.84
V7 V8 V7 V8
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