Tableau Course
Metadata in Tableau
Metadata is data about your data — the field names, data types, descriptions, and formatting properties that describe your dataset. Managing metadata well in Tableau makes your workbooks self-documenting, easier to maintain, and safer for other people to use.
What Metadata Covers in Tableau
Every field in your Data pane carries a set of properties beyond just its values. Together these properties form the field's metadata — and Tableau lets you view and edit most of them without touching the source data.
Viewing and Editing Field Properties
Right-clicking any field in the Data pane and selecting Default Properties opens a submenu with options to change the field's default comment, colour, shape, sort order, number format, and aggregation. These settings persist in the workbook and apply every time the field is used in a new worksheet.
Adding a Field Description (Comment)
A field description is a note you write about what a field means, where it comes from, or how it should be interpreted. It appears as a tooltip when anyone hovers over the field name in the Data pane — making your workbook self-documenting for teammates who did not build it.
Field Description Tooltip — Mockup
Default Aggregation — Changing the Auto-Aggregate
When you drag a Measure onto a shelf, Tableau automatically applies an aggregation. The default for most numeric fields is SUM. For some fields — like a satisfaction score or a rating — the more meaningful default is AVG. You can change the default aggregation so it applies automatically every time the field is used, rather than changing it manually in every chart.
Right-click the field → Default Properties → Aggregation → choose from SUM, AVG, COUNT, COUNT (Distinct), MIN, MAX, STDEV, VAR, or Attribute. The selected aggregation becomes the automatic default for that field across the whole workbook.
The Metadata Grid on the Data Source Tab
The Data Source tab has a dedicated Metadata view that shows all fields in a tabular list rather than as a data preview. Switch to it by clicking the grid icon at the top-left of the data preview area. The Metadata grid shows:
The Metadata grid is the most efficient place to rename multiple fields at once — you can see all original source names alongside their Tableau display names in a single scrollable list. You can also hide fields directly from this view by clicking the eye icon, which removes them from the Data pane without deleting them from the source.
Hiding Fields
Hiding a field removes it from the Data pane so it cannot be accidentally used in a worksheet. The field still exists in the data source and still counts toward extract size unless you exclude it via the Hide Unused Fields option. To hide a field, right-click it in the Data pane or Metadata grid and select Hide. To show it again, select Show Hidden Fields from the Data pane menu, then right-click the greyed-out field and select Unhide.
Most analysts skip metadata entirely and then wonder why their workbooks are confusing to colleagues six months later. A field called "SLS_AMT_USD" with no description, default format of 1200.00, and default aggregation of SUM requires the next person to guess what it means, how it should be formatted, and whether SUM is even the right aggregation. Spending five minutes on metadata — rename the field, set the default number format, add a one-sentence description, and confirm the right default aggregation — pays back that time every time someone opens the workbook. In a published Tableau Server environment, field descriptions are visible to every dashboard consumer who hovers over a field name. Think of metadata as documentation you write once and everyone benefits from forever.
Practice Questions
1. How do you add a description to a field in Tableau so it appears as a tooltip when hovering over the field in the Data pane?
2. Where on the Data Source tab can you see all fields listed with their original source column names alongside their Tableau display names in one place?
3. A satisfaction score field always needs to aggregate as AVG instead of SUM. How do you make AVG the automatic default for this field across the whole workbook?
Quiz
1. You want the Sales field to always display as currency with a $ symbol across every new worksheet without setting the format manually each time. What is the correct approach?
2. What is the main advantage of using the Metadata grid view on the Data Source tab compared to working in the Data pane?
3. What happens to a field when you right-click it in the Data pane and select Hide?
Next up — Lesson 21: Bar and line charts — building the two most fundamental chart types in Tableau with full control over axes, colours, and labels.