Tableau Interview Questions and Answers

This section covers frequently asked Tableau interview questions.

1. What is Tableau?

Tableau is a powerful data visualization and business intelligence tool. It helps transform raw data into easily understandable charts, graphs, and dashboards, enabling better decision-making.

2. Key Features of Tableau.

  • Data Blending: Combining data from multiple sources into a single view.
  • Real-time Analysis: Analyzing live, fast-changing data.
  • Data Collaboration: Sharing dashboards and insights with others.

3. Tableau Tools.

  • Tableau Desktop: For creating and customizing dashboards and workbooks.
  • Tableau Public: A free version for creating and sharing workbooks online.
  • Tableau Online: A cloud-based version for collaboration and sharing.
  • Tableau Server: For publishing and sharing workbooks within an organization.
  • Tableau Reader: For viewing workbooks (no editing allowed).

4. Data Terminologies in Tableau.

Understanding Tableau's terminology is crucial:

  • Bookmark: A saved view of a worksheet.
  • Workbook: The main file containing worksheets, dashboards, and stories.
  • Dashboard: A collection of views displayed on a single page.
  • Data Source Page: Where you configure your data connections.
  • Worksheet: Where you create visualizations (views).
  • Dimensions: Categorical data (e.g., dates, names).
  • Measures: Numerical data (e.g., sales, profits).
  • Shelves (Rows, Columns, Filters, Pages): Areas to place fields for building visualizations.
  • Marks Card: Controls the visual representation of data points.

5. .twb vs. .twbx Extensions.

  • .twb: Stores workbook information (no data).
  • .twbx: A packaged file containing both the workbook and the data source.

6. Traditional BI Tools vs. Tableau.

Feature Traditional BI Tableau
Data Connectivity Often limited Wide range of connections
Performance Can be slow Fast in-memory processing
Data Exploration Less interactive Highly interactive

7. Data Types in Tableau.

  • Date
  • Text
  • Number
  • Date & Time
  • Boolean
  • Geographic

8. Join Types in Tableau.

Tableau supports standard join types, similar to SQL:

  • Cross Join: All combinations of rows.
  • Inner Join: Only matching rows.
  • Left Outer Join: All rows from the left table, with matching rows from the right.
  • Right Outer Join: All rows from the right table, with matching rows from the left.
  • Full Outer Join: All rows from both tables.

9. Maximum Number of Tables Joined.

32.

10. Live vs. Extract Connections.

  • Live: Queries data from the source in real time.
  • Extract: Imports a snapshot of the data for offline analysis.

11. What are Shelves?

Shelves (Rows, Columns, Filters, Pages) are areas in a Tableau worksheet used to place fields to build visualizations.

12. Sets in Tableau.

Sets create subsets of data based on defined conditions. They are dynamic or fixed.

13. Groups in Tableau.

Groups combine members of a dimension to create higher-level categories.

14. Hierarchical Fields.

Hierarchical fields allow drilling down into data at increasingly granular levels.

15. Tableau Data Server.

Tableau Data Server manages data extracts and connections, improving performance and enabling collaboration.

16. Tableau Data Engine.

The Tableau Data Engine is the underlying technology responsible for processing data and generating visualizations. It's designed for efficient query processing, even with large datasets. While it leverages in-memory processing where beneficial, data is primarily stored on disk to handle very large datasets.

17. Creating Calculated Fields

In Tableau, calculated fields allow you to create new data from your existing data. They are useful for performing operations, aggregations, or transformations on the data directly within Tableau. Here's how you can create a calculated field:

Steps to Create a Calculated Field in Tableau:

  1. Open the Calculation Editor: Right-click on any empty area in the Data pane and select “Create Calculated Field”, or click the drop-down menu in the Data pane and choose “Create Calculated Field”.
  2. Enter a Name: In the "Calculated Field" dialog box, enter a descriptive name for your calculated field in the Name field.
  3. Enter the Formula: Use the calculation editor to input your desired formula. Tableau provides a range of functions like SUM, AVG, IF statements, DATE functions, and more for creating your formula. For example:
    Syntax
    
IF [Sales] > 500 THEN "High"
ELSE "Low"
END
  4. Validate the Formula: Tableau will automatically check if your formula is valid. If there’s an error, it will display an error message.
  5. Click OK: Once the formula is validated, click OK to save the calculated field. It will then appear in the Data pane under Dimensions or Measures, depending on the type of calculation.

Example of a Simple Calculated Field:

For instance, to calculate the profit margin, you could create a calculated field using this formula:

Syntax

([Profit] / [Sales]) * 100

Output:

Output

Profit Margin: 15%

Once the calculated field is created, you can use it like any other field in your Tableau visualizations to display results dynamically based on your formula.

18. Dual Axis.

A dual axis allows you to combine two different measures on a single chart, using separate axes for each measure. This is useful for comparing two different metrics side-by-side.

19. Treemap vs. Heatmap.

Chart Type Best Suited For
Treemap Hierarchical data
Heatmap Comparing categories using color and size

20. Data Joining vs. Data Blending.

Method Data Source
Data Joining Single source
Data Blending Multiple sources

21. TDE (Tableau Data Extract) Files.

TDE files store data extracted from various sources. They're optimized for Tableau's in-memory processing and improve query performance.

22. Stories in Tableau.

A story in Tableau is a sequential presentation of dashboards or worksheets, used to narrate a data-driven story.

23. Discrete vs. Continuous Data.

Data Type Description
Discrete Distinct, separate values (e.g., categories).
Continuous Values that can be measured along a continuous scale (e.g., temperature).

24. Row Limits in Tableau.

Tableau can handle very large datasets; it doesn't have a fixed row limit.

25. Tableau on macOS.

Yes, Tableau Desktop is available for macOS.

26. Tableau and Strategic Acquisition.

Tableau's data visualization and analysis capabilities are valuable assets for organizations looking to gain insights from data.

27. Shared Excel Files.

Yes, but extracts are generally recommended for better performance.

28. License Expiration and Dashboard Access.

If a user's license expires, they will lose access to dashboards and workbooks. However, if the data source is an extract, others might still have access, depending on the user's permissions and the location of the extract file.

29. Tableau File Types.

  • Bookmarks (.tbm)
  • Workbooks (.twb)
  • Packaged workbooks (.twbx)
  • Data extract files (.tde or .hyper)
  • Data connection files (.tdc)

30. Published vs. Embedded Data Sources.

Data Source Type Description
Published Independently published; can be used by multiple workbooks
Embedded Embedded in a specific workbook