Databases Reference
In-Depth Information
Measure group
Partition1
Aggregation
Design
Aggregation 1
Aggregation 1
Aggregation 2
Aggregation 2
…
…
Aggregation N
Aggregation N
Partition2
Aggregation 1
Aggregation 2
…
Aggregation N
FIGURE 23.8
Partitions can reference the same aggregation design object.
This metadata design allows a single
AggregationDesign
object and its aggregation objects
to be shared easily by multiple partitions. An aggregation object contains a collection of
dimensions; every dimension element can contain zero or more attributes. A partition
uses the
AggregationDesignID
property to reference an aggregation design object.
Using Data Definition Language to Define Aggregations
Listing 23.1 shows the Data Definition Language (DDL) that defines an aggregation in the
Warehouse
measure group. The aggregation has two attributes: the
Year
attribute (refer-
enced by the
The Year
) from the
Time
dimension, and the
Product Category
attribute
from the
Product
dimension.
LISTING 23.1
DDL for an Aggregation
<Aggregation>
<ID>Aggregation 1</ID>
<Name>Aggregation 1</Name>
<Dimensions>
<Dimension>
<CubeDimensionID>Time</CubeDimensionID>
<Attributes>
<Attribute>
<AttributeID>The_Year</AttributeID>
</Attribute>
</Attributes>
</Dimension>
<Dimension>
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