Answer

1. Connect to the Tableau Server PostgreSQL workgroup database with the Tableau user.
2. Double click on New Custom SQL in the left hand data source pane.
3. Paste the sample query provided below in the text box.
4. Click Ok.
5. From here, you can select the appropriate Backgrounder Task criteria for your visualization.

  SELECT
      tasks.id                                            AS "Job Id" ,
      tasks.job_name                                      AS "Job Name" ,
      tasks.progress                                      AS "Progress" ,
      tasks.finish_code                                   AS "Finish Code" ,
      tasks.priority                                      AS "Priority" ,
      tasks.notes                                         AS "Notes" ,
      tasks.created_at                                    AS "Created At" ,
      tasks.started_at                                    AS "Started At" ,
      tasks.completed_at                                  AS "Completed At",
      tasks.backgrounder_id                               AS "Backgrounder Id",
      tasks.created_on_worker                             AS "Created On Worker" ,
      tasks.processed_on_worker                           AS "Processed On Worker" ,
      current_timestamp                                   AS "Current Datetime" ,
      tasks.site_id                                       AS "Site Id" ,
      s.name                                              AS "Site Name" ,
      tasks.subtitle                                      AS "Item Type" ,
      tasks.item_id                                       AS "Item Id" ,
      tasks.item_name                                     AS "Item Name" ,
      tasks.repository_url                                AS "Item Repository Url" ,
      tasks.project_id                                    AS "Item Project Id" ,
      tasks.owner_id                                      AS "Item Owner Id" ,
      su_own.name                                         AS "Item Owner Name" ,
      su_own.friendly_name                                AS "Item Owner Friendly Name" ,
      p.name                                              AS "Project Name"
  FROM
      (
      SELECT
          bj.id ,
          bj.job_name ,
          bj.progress ,
          bj.finish_code ,
          bj.priority ,
          bj.notes ,
          bj.created_at ,
          bj.started_at ,
          bj.completed_at ,
          bj.site_id ,
          bj.subtitle ,
          bj.backgrounder_id ,
          bj.created_on_worker ,
          bj.processed_on_worker ,
          COALESCE(d.repository_url, w.repository_url)        AS "repository_url" ,
          COALESCE(d.project_id, w.project_id)                AS "project_id" ,
          COALESCE(d.owner_id, w.owner_id)                    AS "owner_id" ,
          COALESCE(dc.id, w.id)                               AS "item_id" ,
          COALESCE(d.name, w.name)                            AS "item_name"
      FROM background_jobs bj
          LEFT JOIN datasources d
              ON bj.title = d.name
                  AND bj.subtitle = 'Datasource'
          LEFT JOIN data_connections dc
              ON d.id = dc.owner_id
  		AND dc.owner_type = 'Datasource'
          LEFT JOIN workbooks w
              ON bj.title = w.name
                  AND bj.subtitle = 'Workbook'
      ) AS tasks
      LEFT JOIN sites s
          ON tasks.site_id = s.id
      LEFT JOIN users u_own
          ON tasks.owner_id = u_own.id
      LEFT JOIN system_users su_own
          ON u_own.system_user_id = su_own.id
      LEFT JOIN projects p
          ON tasks.project_id = p.id

Additional Information

• The readonly or tableau user on the workgroups database must be enabled in Tableau Server (see here for instructions).
• Support does not support diagnosing custom SQL queries.
• In the Tableau Help article: Workgroups Database you will find information related to overview of tables within the workgroup database, their relations to other tables, etc.