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Besides balanced hierarchies, IBM Alphablox cubes support dimensions that are ragged or unbalanced. The following descriptions include issues you should be aware of.
Ragged Hierarchies
In a ragged hierarchy, null values can appear in any of the level columns. Null column values between member names are skipped, so a parent can have a child member multiple levels below the parent level. The children of USA shown in the example below are CA and Washington DC . The levels provide a meaningful context to its members in the ragged hierarchies. Thus, while Washington DC is a child of USA , it is included at the City level with San Francisco and Los Angeles.
Country |
State |
City |
---|---|---|
USA |
CA |
San Francisco |
USA |
CA |
Los Angeles |
USA |
<NULL> |
Washington DC |
Vatican City |
<NULL> |
Vatican City |
Unbalanced Hierarchies
In an unbalanced hierarchy, null values can appear on the lower levels of the hierarchy. A parent member's children will always be in the level below that of the parent. In this hierarchy, the levels do not provide a meaningful context to its members - Washington DC is at the same level as CA in this example. A better example of an unbalanced hierarchy might be an organizational chart.
Level 1 |
Level 2 |
Level 3 |
---|---|---|
USA |
CA |
San Francisco |
USA |
CA |
Los Angeles |
USA |
Washington DC |
<NULL> |
Vatican City |
Vatican City |
<NULL> |
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