Time Hierarchy Overview
The Date dimension defines the start and end dates of the model's time frame. It also specifies the granularity of the time units used in the model (year, quarter, month, week, or day).
It can be maintained both manually and automatically by the system. Leaving the management to the system means that the dimension member values are generated from the parameters within the Dimension Settings panel in the Modeler, and in the model Preferences. Conversely, maintaining the Date dimension manually allows you to edit the master data and manage all dimension members and hierarchies freely.
You can specify a default time hierarchy to display in stories, and optionally configure the date dimension to organize data by fiscal year instead of calendar year. A model can contain more than one date dimension if needed.
Weekly Time Patterns
The supported weekly time patterns are:
Custom Time Hierarchy
Custom time hierarchies help you plan and analyze data using one or more hierarchies. They also allow for company-specific fiscal year variants.
To create a custom time hierarchy, you must first set the Dimension Details for the Date dimension type to User-Managed. Now you can add your own custom time hierarchies and edit the predefined hierarchies that come with the time granularity applied to the dimension.
Time hierarchies are level-based which means they are based on properties in the Date dimension. If you need a custom hierarchy you must add properties first.
Each property you create is assigned to a Semantic Type, which is a time unit assigned to a property within the hierarchy. The Semantic Type options are:
The semantic type Other is reserved for custom properties that you want to attach to other properties as linked descriptions.
Once the properties have a Semantic Type assigned, you can add them as levels within the hierarchy.
Make sure to follow these guidelines:
- The hierarchy has the mandatory Year semantic type as the highest level.
- The semantic types within the hierarchy are ordered from the largest to the smallest time unit. For example, Month must be below Quarter and above Week.
- Each semantic type within the hierarchy is used only once, except for the Other semantic type.
- If the hierarchy uses the semantic type Month, do not include the semantic type Period, and vice versa.
- The lowest level of the hierarchy is the ID property if there is one. Otherwise, it must be a unique property.
- Description properties cannot be used in the hierarchy.
In the example below, the hierarchy has 3 levels:
- Level 3: Season
- Level 2: Holiday
- Level 3: Week
To create a new hierarchy from the Hierarchy Builder, simply click + Create New Hierarchy and then drag and drop the required levels into the custom time hierarchy.
The following chart is an example of a custom time hierarchy displaying sales values for each season and then drilled down to the Easter Season.