Parent-Child Dimensions - Introduction , drawback and alternative approach

First of all lets understand what Parent Child dimensions are and where and When they are modelled.

From MSDN

A parent-child dimension is based on two dimension table columns that together define the lineage relationships among the members of the dimension. One column, called the member key column, identifies each member; the other column, called the parent key column, identifies the parent of each member. This information is used to create parent-child links, which are then combined into a single member hierarchy that represents a single meta data level.

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