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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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► Realignment<br />

This refers to the process of synchronizing (realigning) all related fields after a<br />

change is made to one data field.<br />

► Tablespace partitioning<br />

This refers to the process of reducing the physical size of a large tablespace<br />

into multiple smaller physical parts, according to a common key field —<br />

frequently time-based. Partitioned tablespaces allow parallel access across<br />

multiple partitions. Partitioned tablespaces also allow the accessing of<br />

individual partitions without affecting other partitions.<br />

► <strong>DB2</strong> compression<br />

This process utilizes compression routines, supplied by <strong>IBM</strong>, to compress<br />

<strong>DB2</strong> data at the hardware level.<br />

► <strong>SAP</strong> compression<br />

This refers to the consolidation and summarization of data from an InfoCube’s<br />

F- fact table into its E- fact table. Compression results in the Package ID<br />

being stripped off and all records summarized into the E- fact table.<br />

► Data granularity<br />

This refers to the difference between the frequency that data is updated in an<br />

InfoCube’s F- fact table compared to the frequency in the E- fact table. It<br />

ranges from low to high.<br />

► Low granularity<br />

After compression, a high number of records exist in the F- fact table in<br />

relation to the E- fact table. Take an example where an InfoCube holds a<br />

weekly view of the data, and sales orders were entered, accessed, and<br />

updated many times during the week. There would be many records in the F-<br />

fact table, which would be compressed into a single record in the E- fact table.<br />

► High granularity<br />

After compression, the same number of records is found in the F- fact table as<br />

in the E- fact table. In our example, if sales orders were entered only once a<br />

week <strong>for</strong> each customer, there would be a one-to-one relationship between<br />

the data in the F- fact table and the compressed data in the E- fact table.<br />

28 <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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