When you connect to a new data source, Tableau assigns each field in the data source as dimension or measure in the Data pane, depending on the type of data the field contains. You use these fields to build views of your data.
About data field roles and types
Data fields are made from the columns in your data source. Each field is automatically assigned a data type (such as integer, string, date), and a role: Discrete Dimension or Continuous Measure (more common), or Continuous Dimension or Discrete Measure (less common).
- Dimensions contain qualitative values (such as names, dates, or geographical data). You can use dimensions to categorize, segment, and reveal the details in your data. Dimensions affect the level of detail in the view.
- Measures contain numeric, quantitative values that you can measure. Measures can be aggregated. When you drag a measure into the view, Tableau applies an aggregation to that measure (by default).
Tableau represents data differently in the view depending on whether the field is discrete (blue), or continuous (green). Continuous and discrete are mathematical terms. Continuous means “forming an unbroken whole, without interruption”; discrete means “individually separate and distinct.”
- Green measures and dimensions are continuous. Continuous field values are treated as an infinite range. Generally, continuous fields add axes to the view.
- Blue measures and dimensions are discrete. Discrete values are treated as finite. Generally, discrete fields add headers to the view.
Possible combinations of fields in Tableau
This table shows examples of what the different fields look like in the view. People sometimes call these fields “pills”, but we refer to them as “fields” in Tableau help documentation.
|Continuous Dimensions (dimensions with a data type of String or Boolean cannot be continuous)|
A visual cue that helps you know when a field is a measure is that the field is aggregated with a function, which is indicated with an abbreviation for the aggregation in the field name, such as: . To learn more about aggregation, see List of Predefined Aggregations in Tableau and Aggregate Functions in Tableau.
But there are exceptions:
- If the entire view is disaggregated, then by definition no field in the view is aggregated. For details, see How to Disaggregate Data.
- If you are using a multidimensional data source, fields are aggregated in the data source and measures fields in the view do not show that aggregation.
Examples of continuous and discrete fields used in a view
In the example on the left (below), because the Quantity field is set to Continuous, it creates a horizontal axis along the bottom of the view. The green background and the axis help you to see that it’s a continuous field.
In the example on the right, the Quantity field has been set to Discrete. It creates horizontal headers instead of an axis. The blue background and the horizontal headers help you to see that it’s discrete.
In both examples, the Sales field is set to Continuous. It creates a vertical axis because it continuous and it’s been added to the Rows shelf. If it was on the Columns shelf, it would create a horizontal axis. The green background and aggregation function (in this case, SUM) help to indicate that it’s a measure.
The absence of an aggregation function in the Quantity field name help to indicate that it’s a dimension.