Use Lineage for Impact Analysis
Knowing where your data comes from is key to trusting the data, and knowing who else uses it means you can analyse the impact of changes to data in your environment. The lineage feature in Tableau Catalogue helps you do both these things.
When you have a Data Management licence and Tableau Catalogue enabled, you have access to lineage information for your content. For more information about Tableau Catalogue, see "About Tableau Catalog" in the Tableau Server(Link opens in a new window) or Tableau Cloud(Link opens in a new window) Help.
To see the lineage for an asset, first navigate to the asset's page. Your options for this step include:
- Search for the asset and select it.
- Navigate to it from Explore.
- If it's an external asset (such as a database or table) that's not in a project, navigate to it through External Assets. (This option also works for external assets that are in projects.)
Then select the Lineage tab.
Note: Lineage data for flows won't appear if the flow includes parameter values. For more information about using parameters in flows see Create and Use Parameters in Flows(Link opens in a new window) in the Tableau Prep help.
Lineage shows dependencies in relationship to the lineage anchor, which is the asset selected. A lineage anchor can be a database, table, workbook, published data source, virtual connection, virtual connection table, lens, metric or flow. (In the image above, the anchor is the "Orders (superstore)"data source, and in the image below, the anchor is the "Batters" table.) All the assets below the anchor depend, either directly or indirectly, on the anchor and are called outputs or downstream assets. The assets above the anchor are the assets the anchor is either directly or indirectly dependent on and are called inputs or upstream assets.
Starting in Tableau Cloud June 2023, lineage pages for data sources include search and filtering (in the top-right of the fields list) that allow you to quickly find fields of interest or relevance. (Search and filtering for fields on data source lineage pages is not available in Tableau Server.)
When you select a field in a data source or a column in a table, the lineage is filtered to show only downstream assets that depend on the field (or column) or upstream inputs to the field (or column) as in this 'Superstore' workbook example that shows the lineage filtered for the Commission (Variable) field:
You can select an upstream or downstream asset in the Lineage pane to see its details. For example, when you select Metrics, the list of metrics depending on this workbook appears to the left of the Lineage pane.
From the Lineage pane, you can navigate to any asset related to your initial choice, in this case the workbook, by following the links that interest you.
Tableau Catalogue treats an external asset as ‘embedded’ if the Include external files box is ticked when a data source or workbook is published. When an external asset (database, table or file) is embedded in published Tableau content (workbooks, data sources and flows), the external asset is used by the content, but is not shareable with other users. That embedded external asset appears in the lineage upstream from its Tableau content and is listed in External Assets.
To see if an external asset is embedded, go to the external asset’s detail page and see if ‘Embedded Asset’ is listed under Category.
For information about embedded data, see Publishing data separately or embedded in workbooks(Link opens in a new window) in Tableau Desktop and Web Authoring Help.
Lineage and custom SQL connections
When you view the lineage of a connection that uses custom SQL, keep in mind the following:
- Lineage might not be complete.
- Catalogue doesn't support showing column information for tables that it only knows about through custom SQL.
- Field details cards might not contain links to connected columns, or might not show any connected columns at all.
- Column details cards might not contain links to fields that use the column, or might not show any fields at all.
For more information, see Tableau Catalogue support for custom SQL(Link opens in a new window) in the Tableau Desktop and Web Authoring Help.
Catalogue doesn't support cubes
Cube data sources (also known as multidimensional or OLAP data sources) are not supported by Tableau Catalogue. Tableau content (such as a data source, view or workbook) that relies on cube data does not display any cube metadata or cube lineage in Catalogue.
Mismatch between lineage count and tab count
You might notice a mismatch in the count of assets between the Tableau Catalog Lineage tool and the tabs in Tableau Server or Tableau Cloud.
The count mismatch is explained by the fact that each – lineage count vs tab count – counts assets a different way. For example, at any given point in time, Catalog can count only assets that are indexed, whereas Tableau Server or Tableau Cloud counts any assets that are published. Other reasons for count differences include whether:
- You have ‘View’ permissions for the asset.
- An asset is hidden.
- Any fields are used in a workbook.
- An asset is directly or indirectly connected to.
- An asset is in a Personal Space.
Workbook count mismatch example
As an example, here's how the tab count vs. the lineage count is determined for workbooks.
Connected Workbooks tab counts workbooks that meet both these criteria:
- Connects to the data source (whether or not any fields are actually used in the workbook).
- The user has permissions to view (whether it's a worksheet, dashboard or story).
Tableau Catalogue Lineage counts workbooks that meet all these criteria:
- Has been indexed by Tableau Catalogue.
- Connects to the data source and uses at least one field in the data source.
- Contains worksheets, including dashboards or stories that contain a worksheet, that use at least one field in the data source.
When metadata is blocked because of limited permissions, or the asset is in a Personal Space, Catalogue still counts the workbook. But instead of seeing some of the sensitive metadata, you see Permissions required. For more information, see Access lineage information.
At the end of the lineage is Owners. The list of owners includes anyone assigned as the owner or contact for any content downstream from the lineage anchor.
You can email owners to let them know about changes to the data. (To email owners, you must have the 'Overwrite' (Save) capability on the lineage anchor content.)
- Select Owners to see the list of people who are impacted by the data in this lineage.
- Select the owners you want to send a message to.
- Click Send Email to open the email message box.
- Enter the Subject and your message in the text box, and click Send.