A hierarchy is a very important part of any OLAP ENGINE and allows USERS to drill down from summary levels hierarchies represent the way user expect to explore data at more detailed level

hierarchies is made up of MULTIPULE levels creating the structure based on end user requirements.
->years->quarter->month->week ,are all the levels of calender hierarchy

They are 2 types of hierarchies they are

1. Natural hierarchy
2. Unnatural hierarchy

• Natural hierarchy: This means that the attributes are intuitively related to one another. There is a clear relationship from the top of the hierarchy to the bottom.
  Example: An example of this would be date: year, quarter and month follow from each other, and in part, define each other.

• Unnatural hierarchy: This means that the attributes are not clearly related.
  Example: An example of this might be geography; we may have country -> state -> CITY, but it is not clear where Province might sit.

A hierarchy is a very important part of any OLAP engine and allows users to drill down from summary levels hierarchies represent the way user expect to explore data at more detailed level

hierarchies is made up of multipule levels creating the structure based on end user requirements.
->years->quarter->month->week ,are all the levels of calender hierarchy

They are 2 types of hierarchies they are