Page 31 - DCAP606_BUSINESS_INTELLIGENCE

Business Intelligence

Notes 2.3 Summary

If the dimension is defined as a hierarchy, the lower levels of the hierarchy must also have
an attribute that identifies the parent of each member.

Typically, the key attribute represents the primary key column or columns in the dimension
table.

A hierarchy is a set of parent-child relationships between attributes within a dimension.
These hierarchy attributes are also known as levels.
Level-based hierarchies can contain parent-child relationships.

A parent-child hierarchy is a hierarchy in a standard dimension that contains a parent
attribute.
A hierarchy in which all the lowest-level members do not have the same level of depth is
ragged hierarchy.
The Year, Quarter, and Month attributes are used to construct a user-defined hierarchy,
named Calendar, in the time dimension.
2.4 Keywords

Hierarchy: A hierarchy is a set of parent-child relationships between attributes within a
dimension.

Key attribute: The key attribute is the attribute in a dimension that identifies the columns in the
dimension main table that are used in foreign key relationships to the fact table.
Level-based: This type of hierarchy consists of an ordered set of two or more levels.

Parent-child: A parent-child hierarchy is a hierarchy in a standard dimension that contains a
parent attribute.
Ragged Hierarchy: A hierarchy in which all the lowest-level members do not have the same
level of depth is ragged hierarchy.
Skip-level: A hierarchy in which certain members do not have values for certain higher levels
are known as skip-level hierarchy.

User-defined: These are user-defined hierarchies of attributes that are used in service of Microsoft
SQL.

2.5 Review Questions

1. What is the multi-dimensional analysis?

2. Discuss about the key attribute of dimension attributes.
3. Briefly explain the dimension attribute properties.
4. What is the dimension hierarchy? Explain with example.

5. Discuss are the various type of hierarchy.
6. “Parent-child is actually value-based hierarchy”. Comment.
7. What is ragged hierarchy? Give the suitable example.
8. Explain the relationship between the levels and members of the calendar dimension.

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