A way to organize data at different levels of aggregation. Hierarchies are used to define data aggregation; for example, in a Time dimension, a hierarchy might be used to aggregate data from days to months to quarters to years. Hierarchies are also used to define a navigational drill path.
In a relational table, hierarchies can be defined as part of a dimension object.
See also: level-based hierarchy, ragged hierarchy, skip-level hierarchy, value-based hierarchy
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