Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

Loading from a flat file
You can avoid I/O performance by placing very large flat files on the application
server, instead of remotely on a client machine over a slow network or from tape,
or on the same disk that has heavy I/O activity. In addition, you can try to use
fixed-length ASCII format instead of CVS, where it internally converts into fixed
length format. If possible, split large flat files for parallel processing.
Loading from an R/3 system
If loading from an R/3 system, you can use SM50, SM51, and SM66 to look for
long-running processes to determine whether there is a resource problem on the
source system. Also, you can use Extractor Checker (RSA3) to check for any
extraction problem in the first place.
There are specific SAP notes addressing application areas, and you may want to
refer to them for guidance. You can temporarily turn on an ST05 trace to analyze
SQL statements to identify expensive SQL statements.
Determine whether indexes of datasource tables are okay, and not missing or
needed. Having indexes on the source tables avoids full table scans.
For ST05 trace capture, make sure that you filter only with user-running
extraction and make sure no other parallel extraction is in progress. Next, check
whether runstats are up-to-date for tables that are read from.
If there are more application servers, you may want to spread the load to other
servers in order to avoid bottlenecks from a single server’s CPU and memory
resources. You can do this by configuring table ROIDOCPRMS.
Also note that the data package size defined in this table impacts the frequency
of database commits. In general, define smaller package size for
resource-constrained systems, and larger ones for larger systems (but make
sure that they are not so large that they impact communication processes and
result in a holdup of work processes on the source system). Refer to SAP note
409641 for more details.
A number of other factors can contribute to high extraction time (for example, the
general performance of the R/3 system, a slow network between the R/3 system
and the BW system, resource constraints like not enough CPU, or the memory
resources of the R/3 system).
If custom enhancement exits are used for extraction, the ABAP Runtime Analysis
tool (SE30) can be used to help with debug performance of ABAP coding. It can
help isolate whether the problem is in the area of ABAP, I/O, or SQL by looking at
the time spent in each subroutine.
154 Best Practices for SAP BI using DB2 9 for z/OS