07.02.2013 Views

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

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

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

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

transferred is greater than 10), the aggregate may be useful. Refer to 8.3.2,<br />

“Determining whether aggregates are required” on page 161, <strong>for</strong> more detailed<br />

explanations.<br />

Note that in Figure 8-27 on page 170, the number of rows analyzed is shown as<br />

40,500. This is obviously incorrect (given that 880,091 rows were selected), and<br />

is due to query parallelism. This can be checked by returning to the ST04<br />

overview window, highlighting the line you selected and pressing Details → Avg<br />

Execution Statistics. Then check the Avg Parallel Groups field, as shown in<br />

Figure 8-28.<br />

Figure 8-28 ST04 query parallelism<br />

Chapter 8. Query and Load per<strong>for</strong>mance 171

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!