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

The following query was utilized:
SELECT X, Y, Z FROM CUSTOMER OPTIMIZE FOR 240001 ROWS FOR FETCH ONLY
All column data is CHAR or VARCHAR
240000 rows at 133 bytes per row were returned resulting in a result set size of 31,920,000
bytes.
Performance measurement results
See Table 7-1 for the results.
Table 7-1 DB2 connect evaluation DB2 V7 vs. DB2 V8
DB2 Connect and client V8 performed better for large result sets with DB2 V8 as the DRDA
application server compared to DB2 V7. The retrieval of data from DB2 V8 is 15.2% faster
than from DB2 V7. This improvement is achieved through the support of a 64 KB query block
size and the automatic use of multi-row fetch by DDF in DB2 V8.
Conclusion
The 64 KB query block size can reduce the network transfers by 50% in DB2 V8 compared to
DB2 V7.
Recommendation
In order to benefit from the larger query block size supported by DB2 V8 when dealing with
large result sets, you should update the DB2 client configuration parameter RQRIOBLK value
to 65,635 since the default is 32,767.
7.1.5 DB2 Universal Driver for SQLJ and JDBC
DB2 UDB for Multiplatforms Version 8.1 was the first member of the DB2 Family to introduce
the new JDBC Driver, called the IBM DB2 Universal Driver for SQLJ and JDBC. This new
Java driver architecture is the future basis of all DB2-related Java efforts. It supports what is
called the JDBC type 2 and type 4 Driver.
These drivers are currently supported on DB2 UDB for Linux, Unix, and Windows and DB2 for
z/OS Version 8. They are also available for DB2 for z/OS and OS/390 Version 7, through the
maintenance stream via UQ85607.
Note that with PTF UQ94429 (DB2 V7) and UQ94430 (DB2 V8) for APAR PQ93458, release
2.3 of the DB2 Universal Driver became available.
Refer to 7.3, “WebSphere and the DB2 Universal Driver” on page 292 for more information.
7.2 Multi-row FETCH and INSERT in DRDA
Elapsed time (sec.) Transfer rate (MB/sec.)
DB2 V7 7.111 4.28
DB2 V8 6.176 4.93
Client applications that use the DB2 CLI/ODBC API could already use multi-row fetch and
insert on the client side. The function SQLExtendedFetch() performs an array fetch of a set of
rows. Also for multiple insert, delete, or update, DB2 CLI/ODBC provides an array input
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