# Tableau Interview Questions

Last update: 30 Mar 2020, 30 QuestionsAsk Question
A Quick Overview of Tableau

Tableau is a powerful and growing Data Visualization tool. This is mostly used in the Business Intelligence sector. Its main purpose is to simplify raw data into a very readable and easy to understand format using interactive charts.

We have prepared a list of Tableau interview questions which might be helpful for candidates interested in getting acquainted with this data analytics tool.

Data analysis is its main use and users can create engaging visuals based on the data stored in workbooks in the dashboard. The main advantage of using Tableau is that it can be used easily by a person not having a technical background. The best features Tableau which makes it a very popular choice is:

• Data Blending
• Real-time analysis
• Collaboration of data

## Best Tableau Interview Questions And Answers

This is actually a trick question. There is no limit to the number of rows in a table. Large amounts of data (in petabytes) can be accessed on Tableau but it restricts the number of rows that are needed at a specific time.

Now, maybe you want to see some different data on the Y-Axis. To do that, you shall need the LOD Expression

• Go to Analytics > Create Calculated Field
• In the Calculation editor, start making changes as per your need and enter this expression
`{ INCLUDE [Customer Name] : SUM([Sales]) }`
• When you have finished this, click OK. The newly made LOD Expression is added to Data Pane under Measures.

Note: The above Tableau interview questions and answers are a guide to a basic understanding. These are questions you must know the answer to before going on an interview.

An ATTR() expression in Tableau indicates that there are multiple values to a parameter when only one value was expected.

For example, when blending multiple data sources, the data from secondary sources are wrapped in ATTR() aggregation as Tableau was expecting only one (primary) data source.

DISCRETE CONTINUOUS
Data roles are counted as distinct and separate. Data roles used to measure continuous data.
It can take only one value within a defined range. Value can be anything from a finite to infinite interval
Represented as blue pills on shelves and blue icons in the Data window Represented as Green Pills
Data Joining Data Blending
Combining data from multiple tables but from a single source. Combining data from multiple data sources.
Can be performed by making use of common columns & common data types in a data set Can be performed either Automatically or Custom/Manual by choosing the measures to blended from multiple data sets
0 0

This is a feature in the Marks section in Tableau. It is also known as the Detail Shelf. Detail Button is used to measure the level of detail(LOD) on a marks card.

The Rank() function in Tableau is used to assign ranks to measures(numeric values) in a data set. It is a part of the table functions on the dashboard.

Creating an Age range in Tableau can be done by following these steps:

• Create a bin and edit its field name to Age
• Right-click on the Age field after the above step
• Click on Age > Create Bins
• Change the size of the bins as per requirement
• Now, drag this pill to your visualization

Two measures in Tableau can be combined and represented in a graphical format. This shall use Dual Axis which combine two or more measures at the same time for easy understanding of data.

Parallel Aggregation is a new feature under Data Vectorization in Tableau. Its aim is to reduce the time it takes to run multiple queries by allowing them to run “parallel” during the same time.

One of the easiest chart types is the filled map. To create one, follow these steps:

• Go to the Dimensions shelf
• Click on Geographic Dimension
• Choose “Filled Maps” under Show Me

The Page Shelf is a feature in Tableau which allows users to break a view into a series of individual pages to help understand and analyze how one specific field affects the rest of the data in a visual mode.

The Page Shelf creates a set of pages, each with a different view. Each of these views is based on a member of the field. These newly generated views can be used to compare data with each other in a visual format, hence making the data understandable on a micro-level.

To create a Calendar in Tableau, follow these steps:

• Create a DATE FIELD
• To start Calendar view, right-click drag the Date Field to Column Shelf and select Month/Year as the format
• Now, Right-Click Drag another instance of the Date field towards the Column shelf. Now select Weekday as the discrete format.

Note: The following tableau interview questions are a guide to a basic understanding of the subject. Must read for Engineers switching to Tableau.

Filters are used in Tableau to restrict the number of records in a said dataset.

There are 5 types of Filters that are used for various purposes.

• Extract Filters: This type of filter is used to extract data from a specific data source and creates a copy in the local Tableau Repository. The extract filter is on the top right corner of the data source tab.
• Data Source Filter: This kind of filter is used to filter data at the source level. Its main function is to restrict the number of records in the dataset. It has the same features of Extract Filter on securing data.
• Context Filter: This is a type of an independent filter which is able to create a separate datasheet out of a data set, compute and display the selections made in a worksheet.
• Dimension Filter: This type of filter is used to segregate data on the basis of dimensions. It’s a type of non-aggregated filter in which multiple dimensions, groups, sets, and bins can be added. This type of filter can be applied through the top or bottom conditions, wildcard match and formula.
• Measure Filters: A type of aggregated filter is used to filter on the basis of calculations applied on specific measures. While you may use data values in a Dimension Filter, Measure Filter allows users to segregate measures on the basis of calculations subjected to it.

Most of the performance tuning or optimizing tableau comes down to 3 major points:

• Optimizing for User traffic: This involves optimizing the server to reduce the time spent on processing a user request.
• Optimization for Extracts: This optimization helps the server to refresh the extracts on a published data source. This is highly relevant for organizations having to deal with large amounts of data which changes frequently and needs to be updated.
• Optimizing for Query Heavy Environments: This is a custom server configuration to enhance tableau for query performance in workbooks using extracts as a data source.

Note: The following tableau server interview questions are a guide to a basic understanding of the subject.

A parallel query in Tableau is used to save time while rendering queries. The basic logic behind is that Tableau will make multiple queries, i.e. when data from multiple sources are being used, Tableau makes queries side by side without waiting for one query to finish, hence saving time.

Shadow extracts are a kind of data that Tableau stores when using a file(non-legacy excel) to load data faster. It has a (.ttde) extension. Tableau can store 5 of these files.

Dual Axes in Tableau are independent data measuring parameters that are layered on top of each other. Tableau allows users to compare multiple measures and dual axes are used for comparing different measures having different scales.

• Create a parameter to drive the size of the bins in the view section
• Now, have a manual formula ready to create the bins
• The bin is now created in the histogram

Follow these steps to split a column:

• Select a major field
• Right-click on it and select “Split”
• If the above does not work, click on “Custom Split” and select the data point ranges as start and endpoint for splitting

Follow these steps to create an action in Tableau:

• Go to Workbooks > Actions
• In the action text box, click on the Add Action button and click on Highlight
• Name the action to make it identifiable in the action box
• Next, use the drop-down menu and select a data source to export data to this action
• Selected whether you want the action to be triggered by Hover, Select or Menu
• Now, select a target sheet
• Select the fields which need highlighting
• Click on OK, an action has been created
Extract Live
Is a connection with a static database Is a connection with a dynamic database
User has to manually refresh to update the data set Users don’t have to refresh as this connection will query underlying data from the source
Data is copied from Data Source to local Tableau Server Since data is called from the source, no data is stored for pre-processing

One of the most basic operations to have in a Business Intelligence tool is to connect it to a data source to analyze the data for further use. Tableau offers a wide range of options to export your data in the form of local text files, MS Excel, PDFs, JSON or database & server connections like Tableau Server, MySQL Server, Microsoft SQL Server and many more.

There are in general four ways of joins used to combine data in Tableau.

They are:

• Right
• Left
• Inner
• Full Outer

TDSX file refers to a Packaged Data Source file. It is basically a .zip file that contains the data source file(.tds) and any other local file data like extract files(.hyper or .tde), Excel workbooks, text files, local cube files, and access files. This kind of file is used to create a single file that can be then shared with others not having access to the original data source.

A Tableau workbook is similar to an Excel workbook and has many overlapping functionalities. It is designed to contain multiple workbooks or dashboards combining all work. Its main aim is to organize, save and share results with concerned users.

Note: These are tableau developer interview questions. Candidates who are deciding to switch to Tableau or looking for a job must read this.

Sets Groups
Is an extracted combination of multiple rows from a workbook Used to combine items and compare with other values
Little hard to use but flexible Easy to use with limited functionalities
Is dynamic in nature Is static in nature

Shelves are containers to store data, i.e. pills in the form of columns, rows, pages and filters which are used for the creation of visualizations.

To show a card in Tableau follow these steps:

• Go to the toolbar
• Click on Show/Hide Card
• Select the cards to be shown

Legends are time fields placed on Color, Size or Shape on the Marks Card. Using these legends can enhance the dashboard, interactivity and save a lot of space.
Follow these steps to create one:

• Go to the dashboard and select a sheet
• Go to the top right of the screen and click on the Drop-Down Menu
• Click on Legends and choose the one you require