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

The Index information tab shown in Figure 8-41 gives you the details below:
► Index - names of the indexes that are used by the query.
► Index Columns - Tells you which key is used for the index.
► Reorg - Is there a requirement to do a reorg?
► Part - This column gives you information of the partition used.
Figure 8-41 Index Information
From the Index information tab you are able to navigate directly to the storage
parameters (SE14) and to the data set space information (DB02). The DB2
installation parameters can be accessed directly from within the Explanation of
SQL Access Path window.
The most important question is whether the execution plan seems to be good.
But this is not easy, especially if the query consists of many tables. But because
we know that an SAP BI query on a cube is represented by a snowflake schema,
usually the best execution plan is the one that accesses the most filtering
dimensions first, which means before the E- fact table access. So for query
analysis it is important to know the cardinalities and filter factor of dimension
branches. For getting this information more easily, SAP developed a new tool,
the SAP Query Visualizer, that makes it very simple to get all the filtering
information with only a few mouse clicks.
Chapter 8. Query and Load performance 185