Tableau Interview Questions and Answers
What is Tableau?
Tableau is a data analytics and visualization tool. Its is 10 times faster than other analytic tools. Built on groundbreaking technology, Tableau desktop converts imaged data into optimized data queries and users can create interactive dashboards. Visually it is too attractive and provide light weight interface.
Explain the importance of Tableau
With instantaneous and powerful data visualization techniques, Tableau Software easily connects to any data source (Corporate Data Warehouse, Microsoft Excel or other). It supports quicker drop-and-down interface processes for creating visual reports of massive amounts of data. The best part is that all data in Tableau from various sources is created equally irrespective of the data type.
What is Data Visualization?
A much advanced, direct, precise and ordered way of viewing large volumes of data is called data visualization. It is the visual representation of data in the form of graphs and charts, especially when you can’t define it textually. You can show trends, patters and correlations through various data visualization software and tools; Tableau is one such data visualization software used by businesses and corporates.
List differences between Tableau desktop and Tableau Server.
While Tableau desktop performs data visualization and workbook creation, Tableau server is used to distribute these interactive workbooks and/or reports to the right audience. Users can edit and update the workbooks and dashboards online or Server but cannot create new ones. However, there are limited editing options when compared to desktop. Tableau Public is again a free tool consisting of Desktop and Server components accessible to anyone.
What are the type of tableau server are there?
There are two type of tableau servers. Tableau server enterprise edition and Tableau Online.
Tableau server enterprise edition is an on premises edition of server, which needs hardware and software resources to be installed. Whereas Tableau Online is a cloud platform of server. It need subscription based access to secure server of tableau. It does need any local setup.
Define Data Modeling.
Data Modeling in Tableau allows rapid analysis of operational data that produce visual prints of data to help users identify consumer trends, sales targets and operational improvement. Data modeling processes minimize the use of manual changes in the data structure but promote automatic adaption to the changing environment.
It also allows real-time modeling by letting users share their analysis in the collaborative working environment.
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.
List the difference between parameters and filters in Tableau.
The difference actually lies in the application. Parameters allow users to insert their values, which can be integers, float, date, string that can be used in calculations. However, filters receive only values users choose to ‘filter by’ the list, which cannot be used to perform calculations.
Users can dynamically change measures and dimensions in parameter but filters do not approve of this feature.
Define fact table and Dimension table in Tableau.
Facts are the numeric metrics or measurable quantities of the data, which can be analyzed by dimension table. Facts are stores in Fact table that contain foreign keys referring uniquely to the associated dimension tables. The fact table supports data storage at atomic level and thus, allows more number of records to be inserted at one time. For instance, a Sales Fact table can have product key, customer key, promotion key, items sold, referring to a specific event. Dimensions are the descriptive attribute values for multiple dimensions of each attribute, defining multiple characteristics. A dimension table ,having reference of a product key form the fact table, can consist of product name, product type, size, color, description, etc.
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.
State limitations of parameters in Tableau.
Parameters facilitate only four ways to represent data on a dashboard (which are seven in quick filters). Further, parameters do not allow multiple selections in a filter.
Define 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.
Define Data Blending.
Unlike Data Joining, Data Blending in tableau allows combining of data from different sources and platforms. For instance, you can blend data present in an Excel file with that of an Oracle DB to create a new dataset.
What is Content Filter?
The concept of context filter in Tableau makes the process of filtering smooth and straightforward. It establishes a filtering hierarchy where all other filters present refer to the context filter for their subsequent operations. The other filters now process data that has been passed through the context filter.
Creating one or more context filters improves performance as users do not have to create extra filters on large data source, reducing the query-execution time.
You can create by dragging a filed into ‘Filters’ tab and then, Right-Click that field and select ‘’Add to Context”
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.
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 Datasource (.tds)
• Tableau Packaged Datasource (.tdsx)
• Tableau Data extract (.tde)
• Tableau Bookmark (.tdm)
• Tableau Map Source (.tms)
• Tableau Preferences (.tps)
Explain the difference between .twb and .twbx
.twb is the most common file extension used in Tableau, which presents an XML format file and comprises all the information present in each dashboard and sheet like what fields are used in the views, styles and formatting applied to a sheet and dashboard.
But this workbook does not contain any data. The Packaged workbook merges the information in a Tableau workbook with the local data available (which is not on server). .twbx serves as a zip file, which will include custom images if any. Packaged Workbook allows users to share their workbook information with other Tableau Desktop users and let them open it in Tableau Reader.
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
• Vertical
• Text
• Image Extract
• Blank page
• Web [URL ACTION]
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
Help> Setting and Performance > Stop 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.
Define 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 Perform Testing in Tableau?
Performance testing is again an important part of implementing Tableau. This can be done by loading Testing Tableau Server with TabJolt, which is a “Point and Run” load generator created to perform QA. While TabJolt is not supported by Tableau directly, it has to be installed using other open source products.
Explain the concept of Dual Axis?
Dual Axis is an excellent phenomenon supported by Tableau that helps users view two scales of two measures in the same graph. Many websites like Indeed.com and other make use of dual axis to show the comparison between two measures and their growth rate in a septic set of years. Dual axes let you compare multiple measures at once, having two independent axes layered on top of one another.
How many maximum tables you can join in Tableau?
The maximum number of 32 tables can be joined in Tableau. A table size must also be limited to 255 columns (fields).
How to remove ‘All’ options from a Tableau auto-filter?
The auto-filter provides a feature of removing ‘All’ options by simply clicking the down arrow in the auto-filter heading. You can scroll down to ‘Customize’ in the dropdown and then uncheck the ‘Show “All” Value’ attribute. It can be activated by checking the filed again.
How to add Custom Color to Tableau?
You can choose the color mark and use custom color in the different color pallet to apply custom colors to a visualization.
What different products Tableau provide?
- Tableau Server: on-premise or cloud-hosted software to access the workbooks built
• Tableau desktop: desktop environment to create and publish standard and packaged workbooks.
• Tableau Public: workbooks available publicly online for users to download and access the included data.
• Tableau Reader: get a local access to open Tableau Packaged workbook
How can you display top five and last five sales in same view?
Create two sets, one for top 5 another for bottom 5 and the join these two sets displaying a unique set of total 10 rows.
What is TDE file?
TDE is a Tableau desktop file that contains with a .tde extension referring to the file containing data extracted from external sources like MS Excel, MS Access or CSV file.
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.
Can parameters have dropdown list?
Yes, parameters do have their independent dropdown lists enabling users to view the data entries available in the parameter during its creation.