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

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In addition, each cube, especially large ones, can be configured to distribute to a<br />

set number of blades <strong>for</strong> indexing, depending on the configured number of parts.<br />

The cube is considered to be very large if it contains several hundred million<br />

rows. Since different cubes could have different numbers of columns, the<br />

number of cells is a more accurate method of deciding whether a cube is large.<br />

By default, 100 million cells (number of rows x column key figures) is a threshold<br />

to determine that the cube is large, and thus a candidate <strong>for</strong> horizontal<br />

partitioning. Figure 11-4 illustrates the horizontal partitioning concept.<br />

Figure 11-4 Horizontal partitioning<br />

All InfoCubes used in this study were in this large cube category and were<br />

candidates <strong>for</strong> partitioning. Our study threshold setting was 250 million cells.<br />

Certain tests were conducted with 27 parts and others with 40 parts. The number<br />

of parts is a trade-off between having more parallel tasks and having more<br />

interblade communication traffic. This setting can be implemented with the<br />

TREXAdmin tool:<br />

Tree > index > scrolling down to the bottom<br />

242 <strong>Best</strong> <strong>Practices</strong> <strong>for</strong> <strong>SAP</strong> <strong>BI</strong> <strong>using</strong> <strong>DB2</strong> 9 <strong>for</strong> z/<strong>OS</strong>

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