One main difference between QlikView and many other database viewers, OLAP tools etc. is that in QlikView there is no need to predefine any hierarchies in the input data. The unique internal logic of QlikView gives you the complete freedom to access any field as a full dimension in any order you like. For most purposes this freedom is extremely powerful.
However, there are occasions when a predefined hierarchy could actually help you to display data more efficiently. QlikView therefore offers the possibility to define groups of fields. The groups can be hierarchic (drill-down) or non-hierarchic (cyclic).
Groups are created in the Groups page of the Document Properties dialog. They can be used in charts, where they appear together with the available fields in the dimension drop-down boxes on the Dimension.
Any fields can be grouped together.
Drill-down groups are marked with an 
icon,
while cyclic groups are displayed with an 
icon.
Hierarchic Groups (Drill-Down)
When several fields form a natural hierarchy, it makes sense to create a drill-down group. Typical examples of hierarchic groups could be:
Time:Year, Quarter, Month
or
Geography: Continent, Country, State, City
When a drill-down group is used as a dimension in a chart, the chart will use the first field in the group's list of fields that has more than one possible value. If selections are made that cause the field to have only one possible value, the next field in the list will be used instead, provided that it has more than one possible value. If no field in the list has more than one possible value, the last field will be used anyway.
In the first example above, Year will be used as chart dimension until a single year is selected. The chart will then show Quarter. If a single quarter is selected, the chart will switch to Month.
As selections disappear, so that more than one value becomes possible in the upper fields of the group's field list, the chart will automatically be drilled back up. Forced drill-up can be achieved by clicking on the drill-up icon in the chart.
