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

2.3% and CPU time at the server with 8.1% again due to the architectural changes in DB2 V8,
see Figure 7-5.
seconds
6
4
2
0
5.7 5.6
single
row
n=
10
V7 : n= # of single-row Insert SQL calls / message
V8 : n= # of rows per multi-row Insert SQL call / message
Figure 7-5 Multi-row insert - DB2 client to host
Multi-row Insert Performance
Distributed - DB2 client Host
(10,000 rows Inserted / test)
Client
Elapsed Time
2.0
1.4 1.5 1.4 1.4
1.0
0.8 0.8
n=
100
n=
1000
n=
10000
2.0 1.9
single
row
1.1
0.7
V8 V7
If the client application is coded to use array insert the difference with DB2 V7 becomes
significant. In DB2 V7 this results still in single row inserts (the array insert only affects the
processing between the application and the CLI/ODBC Driver) but in DB2 V8 full advantage is
taken from multi-row insert between the DIST and DBM1.
For an application that inserts 10 times an array of 1,000 rows this results in a CPU time
improvement of 51% at the DRDA application server side, and an elapsed time improvement
of 47% for the client application, compared to DB2 V7.
If the ODBC Driver detects DB2 V8 as the server it translates the insert into a network
transfer of 1 insert of 1,000 rows. If the ODBC Driver detects a pre-V8 server then each
network transfer becomes 1,000 inserts of 1 row each.
Conclusion
Although there is no DB2 client support for native multi-row fetch, the CLI/ODBC
SQLExtendedFetch() function fetches arrays from the query block result sets. At the server
side the DIST address space will start using multi-row fetch by default and fetch a number of
rows that will fit the query block size which results in significant CPU savings.
If your CLI/ODBC applications currently use array insert, you will immediately benefit from this
enhancement as this SQL syntax will now be honored by DB2 V8 in NFM and not be
translated by the CLI/ODBC Driver into a series of individual row inserts.
n=
10
Server
CPU Time
1.0 1.0
0.5 0.5 0.5
n=
100
n=
1000
1.1
n=
10000
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