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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

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To drill down to an individual execution of a particular query, double-click the<br />

query name. See Figure 8-18.<br />

Figure 8-18 Sample list of executions of a query<br />

You then get a pop-up window with a row of data <strong>for</strong> each individual execution of<br />

the query. In the top left corner of the pop-up, switch the view from Standard Info<br />

to RSDDSTAT Info.<br />

You can identify the execution of the query you are interested in by the UNAME<br />

column and the STARTTIME columns. See Figure 8-19.<br />

Figure 8-19 Example STARTTIME time in RSDDSTAT<br />

This time is taken from the database server of your BW system. On your z/<strong>OS</strong><br />

server there are two times: LOCAL and UTC/GMT. (Note that this is the<br />

UTC/GMT time on z/<strong>OS</strong>, not the LOCAL time.) The <strong>for</strong>mat of the start time is<br />

YYYYMMDDhhmmssmmmuuun. In this example, this start time represents 2004<br />

October 26 21:09:16.<br />

You can now analyze your query to identify the major component of the response<br />

time. In the following sections we discuss how to identify and analyze our three<br />

main components of response time:<br />

► Aggregates required?<br />

► Database processing time<br />

► Front-end processing time<br />

8.3.2 Determining whether aggregates are required<br />

In this section we discuss how to identify whether your query response time can<br />

be improved by the use of aggregates.<br />

Chapter 8. Query and Load per<strong>for</strong>mance 161

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