Tableau Server Interview Questions

What is Tableau Server?

Tableau Server is an enterprise wide visual analytics platform for creating interactive dashboards. Published in: Data & Analytics

What is data visualization?

Data visualization refers to the techniques used to organize and present information intuitively (e.g. points, lines or bars). According to Tableau, using Tableau visualizations, you gain the ability to quickly answer questions; your data becomes a competitive advantage instead of an underutilized asset.

What is the difference between Quick Filter, Normal filter and Context filter?

In Tableau, filters are used to restrict the data from database. The differences between Quick and Normal/ Traditional filter are:

-Normal Filter is used to restrict the data from database based on selected dimension or measure. A Traditional Filter can be created by simply dragging a field onto the ‘Filters’ shelf.

-Quick filter is used to view the filtering options and filter each worksheet on a dashboard while changing the values dynamically (within the range defined) during the run time.

-Context Filter is used to filter the data that is transferred to each individual worksheet. When a worksheet queries the data source, it creates a temporary, flat table that is uses to compute the chart. This temporary table includes all values that are not filtered out by either the Custom SQL or the Context Filter.

What are the limitations of context filters?

Tableau takes time to place a filter in context. When a filter is set as context one, the software creates a temporary table for that particular context filter. This table will reload each time and consists of all values that are not filtered by either Context or Custom SQL filter.

What is data blending? When do you use this?

According to Tableau, Data blending is the ability to bring data from multiple data sources into one Tableau view, without the need for any special coding.

You can use data blending in Tableau in the following cases:

Filter on secondary dimension fields

Use secondary dimensions in the view

Link data between two data sources using fields that are not in the view

If you are combining data from the same data source, such as Excel worksheets or tables in an Oracle database, you use joining.

Name the file extensions in Tableau.

There are a number of file types and extensions in Tableau:

-Tableau Workbook (.twb)

-Tableau Packaged Workbook (.twbx)

-Tableau Data Source (.tds)

-Tableau Packaged Datasource (.tdsx)

-Tableau Data extract (.tde)

-Tableau Bookmark (.tdm)

-Tableau Map Source (.tms)

-Tableau Preferences (.tps)

What are the differences between twb and twbx?

A twb is an xml document which contains all the selections and layout made you have made in your Tableau workbook. It does not contain any data.

A twbx is a ‘zipped’ archive containing a twb and any external files such as extracts and background images.

What are Extracts and Schedules in Tableau server?

Data extracts are the first copies or subdivisions of the actual data from original data sources. The workbooks using data extracts instead of those using live DB connections are faster since the extracted data is imported in Tableau Engine.
After this extraction of data, users can publish the workbook, which also publishes the extracts in Tableau Server. However, the workbook and extracts won’t refresh unless users apply a scheduled refresh on the extract. Scheduled Refreshes are the scheduling tasks set for data extract refresh so that they get refreshed automatically while publishing a workbook with data extract. This also removes the burden of republishing the workbook every time the concerned data gets updated.

Name the components of a Dashboard?

-Horizontal- Horizontal layout containers allow the designer to group worksheets and dashboard components left to right across your page and edit the height of all elements at once.

-Vertical- Vertical containers allow the user to group worksheets and dashboard components top to bottom down your page and edit the width of all elements at once.

-Text

-Image Extract: – A Tableau workbook is in XML format. In order to extracts images, Tableau applies some codes to extract an image which can be stored in XML.

-Web [URL ACTION]:- A URL action is a hyperlink that points to a Web page, file, or other web-based resource outside of Tableau. You can use URL actions to link to more information about your data that may be hosted outside of your data source. To make the link relevant to your data, you can substitute field values of a selection into the URL as parameters.

How to view underlying SQL Queries in Tableau?

Viewing underlying SQL Queries in Tableau provides two options:

-Create a Performance Recording to record performance information about the main events you interact with workbook. Users can view the performance metrics in a workbook created by Tableau.
Help> Settings and Performance> Start Performance Recording

-Reviewing the Tableau Desktop Logs located at C:\Users\\My Documents\My Tableau Repository. For live connection to data source, you can check log.txt and tabprotosrv.txt files. For an extract, check tdeserver.txt file.

What is Page shelf?

Tableau provides a distinct and powerful tool to control the output display known as Page shelf. As the name suggests, the page shelf fragments the view into a series of pages, presenting a different view on each page, making it more user-friendly and minimizing scrolling to analyze and view data and information. You can flip through the pages using the specified controls and compare them at a common axle.

How to use group in calculated field?By adding the same calculation to ‘Group By’ clause in SQL query or creating a Calculated Field in the Data Window and using that field whenever you want to group the fields.

Using groups in a calculation. You cannot reference ad-hoc groups in a calculation

Blend data using groups created in the secondary data source:Only calculated groups can be used in data blending if the group was created in the secondary data source.

Use a group in another workbook. You can easily replicate a group in another workbook by copy and pasting a calculation.

What are the differences between groups and sets?

Groups simplify large numbers of dimension members by combining them into higher-level categories. Sets create a custom field based on existing dimensions that can be used to encode the view with multiple dimension members across varying dimension levels.

Define parameters in Tableau and their working.

Tableau parameters are dynamic variables/values that replace the constant values in data calculations and filters. For instance, you can create a calculated field value returning true when the score is greater than 80, and otherwise false. Using parameters, one can replace the constant value of 80 and control it dynamically in the formula.

How do we do testing in Tableau?

You can do performance testing on Tableau with Tableau Server load-testing solution called TabJolt. You can use Tab Jolt to push a heavy workload onto Tableau Server to give it a jolt and study how the server bends or breaks under load.

What are Quick Filters in Tableau?

Global quick filters are a way to filter each worksheet on a dashboard until each of them contains a dimension. They are very useful for worksheets using the same data source, which sometimes proves to a disadvantage and generate slow results. Thus, parameters are more useful.

How do you add custom color to Tableau?

Tableau offers three types of color palettes: categorical, sequential, and diverging. You can create your own custom color palette by modifying the Preferences.tps file that comes with Tableau Desktop. The Preferences.tps file is located in the My Tableau Repository. The preferences file is a basic XML file that you can open in a text editor to modify. In tableau 9.0 version there is a color picker option.

What is Assume referential integrity?

Referential integrity is a concept which ensures that relationships between databases/tables remain consistent, i.e. it ensures that the references to data are valid. You can improve query performance by selecting this option from the data menu. When you use this option, Tableau will include the joined table in the query only if it is specifically referenced by fields in the view.

Explain when would you use Joins vs. Blending in Tableau?

If data resides in a single source, it is always desirable to use Joins.  When your data is not in one place blending is the most viable way to create a left join like the connection between your primary and secondary data sources.

What is default Data Blending Join?

Data blending is the ability to bring data from multiple data sources into one Tableau view, without the need for any special coding. A default blend is equivalent to a left outer join. However, by switching which data source is primary, or by filtering nulls, it is possible to emulate left, right and inner joins.

What do you understand by blended axis?

In Tableau, measures can share a single axis so that all the marks are shown in a single pane. Instead of adding rows and columns to the view, when you blend measures there is a single row or column and all of the values for each measure is shown along one continuous axis. We can blend multiple measures by simply dragging one measure or axis and dropping it onto an existing axis.

What is story in Tableau?

A story is a sheet that contains a sequence of worksheets or dashboards that work together to convey information. You can create stories to show how facts are connected, provide context, demonstrate how decisions relate to outcomes, or simply make a compelling case. Each individual sheet in a story is called a story point.

What is the difference between discrete and continuous in Tableau?

There are two types of data roles in Tableau – discrete and continuous dimension.

-Discrete data roles are values that are counted as distinct and separate and can only take individual values within a range. Examples: number of threads in a sheet, customer name or row ID or State. Discrete values are shown as blue pills on the shelves and blue icons in the data window.

-Continuous data roles are used to measure continuous data and can take on any value within a finite or infinite interval. Examples: unit price, time and profit or order quantity. Continuous variables behave in a similar way in that they can take on any value. Continuous values are shown as green pills.

How do you automate reports using Tableau software?

This is how you can automate the reports: while publishing the report to Tableau server, you will find the option to schedule reports. Click on this to select the time when you want to refresh the data.

How can we combine database and flat file data in Tableau desktop?

You can combine them by connecting data two times, one for database tables and one for flat file. The Data->Edit Relationships. Give a join condition on common column from db tables to flat file.

What are the platforms Tableau server can run on?

Tableau server can run on Windows and Mac.

Does Tableau integrate with Hadoop/Hive Server?

Tableau can only integrate with HiveServer, not Hadoop.

How do you normalize data for use in Tableau?

When an Excel data source (other than a cube) is already formatted as a cross-tabulation or is otherwise aggregated, options for viewing, aggregating, and grouping in Tableau are limited. Tableau cannot see underlying data points that have already been summarized into a higher-level group or order. To take advantage of Tableau’s full functionality, you need to normalize the data before connecting to it from Tableau.

Explain and implement a serialization of a binary tree.

You can write serialization for leaf nodes, and then for parent nodes.

Recursive map: {value: [serialize(left), serialize(right)]}, where serialized leaf is null.

Got a question for us? Please mention it in the comments section and we will get back to you.

What is aggregation and disaggregation of data in Tableau?

Aggregation and disaggregation in Tableau are the ways to develop a scatterplot to compare and measure data values. As the name suggests, aggregation is the calculated form of a set of values that return a single numeric value. For instance, a measure with values 1,3,5,7 returns 1. You can also set a default aggregation for any measure, which is not user-defined. Tableau supports various default aggregations for a measure like Sum, average, Median, Count and others.
Disaggregating data refers to viewing each data source row, while analyzing data both independently and dependently.

Can parameters have drop down list?

Yes, parameters do have their independent dropdown lists enabling users to view the data entries available in the parameter during its creation.

What are differences between Tableau’s Desktop/Online versions?

Tableau Desktop is used to visualize and analyze data, create workbooks, visualizations, dashboards and stories.

Tableau Desktop Professional (but not Desktop Personal) can then publish these to Tableau Server, Tableau Online and Tableau Public.

Tableau Server and Tableau Online allow you to safely distribute the interactive workbooks to the right people. You can edit workbooks, visualizations, dashboards and stories in Server or Online, but you can’t produce new ones. The editing options are limited compared to the Desktop.

Server and Online can be used as high-performance data repositories for Desktop users.

Tableau Public is a free tool that is intended for people who want to publish information, accessible to anyone. There are both a Desktop and Online components.

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2 Responses on Tableau Server Interview Questions"

  1. BIKASH MOhANTY says:

    Hi ,
    Can you let me know whats the difference between a combined field and a group , and any scenarios where the former is preferred or latter

  2. Prashant K says:

    Combine field concatenate the value of one field with another.
    e.g.
    Col1, Col2, CombinedField
    A,B,”A,B”
    C,D”C,D”
    E,F,”E,F”

    Group helps to aggregate multple rows into one.
    Col1,Sales
    A,100
    B,100
    C,100
    D,100
    E,100
    F,100

    By Grouping C-F, and assuming that we are summing-up the sales, we get
    A,100
    B,100
    C-F,400

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