Databases Reference
In-Depth Information
Figure 9-73
Building Aggregations
Aggregations are what make OLAP fast to use. They are pre-calculated sum-
maries of the data. In Analysis Services, the storage and processing schemes
are linked through the setting of caching options. Caching is a way to in-
crease query response time by keeping the data used most often on a local
disk.
To start the Aggregations Design wizard, click Design Aggregations in the
Partitions tab of the cube designer. You use this wizard to create aggrega-
tions for each partition to improve overall query performance. You learn about
aggregations in detail in
Chapter 13
.
When you run the wizard, the perform-
ance benefits gained are graphically compared to the storage space required
to store the aggregations, as shown in
Figure 9-74
where you can see that
the Performance Gain is set to 30%. A good starting target should be around
25% to 30%, but you will learn about the Usage Based Optimization Wizard in
Chapter 13
for fine-tuning performance gains even further.
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