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Tableau Interview Questions

Tableau Interview Questions

Q. What is the difference between context filter to other filters?

Whenever we crate context filter >> Tableau will create a temporary table for this particular filter set and other filters will be apply on context filter data like cascade parameters… suppose we have crated context filter on countries >> we have chosen country as USA and India >> Tableau will create a temporary table for this two countries data and if you have any other filers >>other will be apply on this two countries data if we don’t have any context filter >> each and individual record will check for all filters


Q. What is disadvantage of context filters?

*The context filter is not frequently changed by the user – if the filter is changed the database must recomputed and rewrite the temporary table, slowing performance.

*When you set a dimension to context, Tableau crates a temporary table that will require a reload each time the view is initiated. For Excel, Access and text data sources, the temporary table created is in an Access table format. For SQL Server, My SQL and Oracle data sources, you must have permission to create a temporary table on your server. For multidimensional data source, or cubes, temporary tables are not crated, and context filters only defined which filters are independent and dependent.


Q. What are the five main product offered by Tableau company?

Tableau offers five main products: Tableau Desktop, Tableau Server, Tableau Online, Tableau reader and Tableau Public.


Q. What is the current latest version of Tableau Desktop(as of Feb.2015)?

Current versions: Tableau Desktop version 9


Q. What is data visualization?

Data visualization refers to the techniques used to communicate data or information by encoding it as visual objects (e.g. points, lines or bars) contained in graphics.


Q. What is Tableau Desktop?

Tableau Desktop is based on breakthrough technology from Stanford University that lets you drag & drop to analyze data. It is great data visualization tool, you can connect to data in a few clicks, then visualize and crate interactive dashboards with a few more.


Q. Why tableau?

Whether your data is in an on-premise database, a database, a data warehouse, a cloud application or an Excel file, you can analyze it with Tableau. You can create views of your data and share it with colleagues, customers, and partners. You can use Tableau to blend it with other data. And you can keep your data up to date automatically


Q. What are the differences between Tableau Software, GoodData and Traditional BI (Business Objects, etc.)?

You could talk feature – functionality for days, but at a high level there are four major differences.

  1. Speed: How fast can you get up and running with the system, answer questions, design and share dashboards and then change them? This is Where systems like Tableau and GoodData are far better than old – school business intelligence like Business Objects or Cognos. Traditional systems took months or years to intelligence like Business Objects or Cognos. Traditional systems took months or years to implement, with costs running to millions. Tableau has a free trail that installs in minutes and GoodData is cloud – based, so they are faster to implement by orders of magnitude. They are also faster to results: traditional BI requires IT and developers to make any changes to reports, so business users are struck in a queue waiting to get anything done. Tableau and GoodData provide more of a self – service experience.
  1. Analysis layer: This is where Tableau excels. It has a powerful and flexible drag & drop visualization engine based on some technology from Stanford. GoodData and traditional BI typically provide some canned reports but changing them requires significant time and money.
  1. Data layer: This is where the three options are most different:

GoodData requires you to move your data to its cloud. Traditional BI typically requires you to move your data to its data warehouse system. Tableau connects to a variety of existing data source and also provides a fast in – memory data engine, essentially a local database. Since most enterprises have their data stored all over the place, this provides the most choice and lets companies use the investment they’ve already made.

  1. Enterprise readiness: Traditional BI and Tableau do well here, with enterprise – level security and high scalability.

Q. What are Filters? How many types of filters are there in Tableau?

Filter is nothing but it is restricted to unnecessary, it is showing exact data. Basically filters are 3 types.

  1. Quick filter
  2. Context filter
  3. Datasource filter

Q. What is disaggregation and aggregation of data?

Suppose I have data like

Eid Ename Salary Dept

1.abc 2000 java

2.bbc 3000 .net

3.Krishna 2500 java

  1. Madhu 300

5.Vamshi 3000 mainframes

1.abc 1000 testing

2.bbc 3000 tableau

3.krishna 5000.net

4.Madhu 7000 testing

  1. vanshi 9000 tableau

1 abc 11000 Mainframes

2 bbc 13000testing

3 krishna 15000 java

4 Madhu 17000 .nte

5 vamshi 19000.net

Aggregation: to display aggregate data

Sum/avg salary by each individual employee

  1. drag ename on columna and salary on rows we will get sum (salary) of each and individual employee
  2. now change measure type as Avg

Choose salary option – choose measure types as “Avg”

Disaggregation: To display each and every transaction

When you look at the aggregated data in the views above, each bar represents all transactions for a specific employee summed up or averaged into a single value. Now say that you want to see the individual salary transactions for each employee. You can create a view like that by selecting Analysis>Aggregate Measures.


Q. How to remove the All options from a Tableau auto – filter?

Right click filter>>customize>>uncheck show all option


Q. Can we use non – used columns (Columns which are not used in reports but data source has columns) in Tableau Filters?

Yes!

Ex. In data source I have column like

empID, EmpName, EmpDept,EmpDsignation, EmpSalary

In reports I am using empname on columns and empsalry on rows.

I can use empDesignation on Filters


Q. What is benefit of Tableau extract file over the live connection?

Extract can be used anywhere without any connection and you can build your own visualizations without connecting to Database.


Q. How to combine two excel files with same fields but different data (different years)?

I have 5 different excel files (2007.xls, 2008.xls..2011.xls) with same fields (film name, genre, budge, rating, profitability) but with data from different year (2007 to 2011). Can someone tell me how can I combine the film name, genre and profitability so that I can see the visualization of 2007 to 2011 in a single chart?


Q. Max no of tables we can join in Tableau?

We can join max 32 table, it’s not possible to combine more than 32 tables.


Q. What is the difference between joining and blending in Tableau?

Joins in Tableau:

For EX: your client is in Healthcare domain and using SQL Server as their database. In SQL server there may be many Tableau like Claims Tables, Rejected Claims Table, Customer Table. Now, client wants to know customer wise claims and customer wise rejected claims table using the joins. Join is a query that combines the data form 2 or more tables by making use of Join condition.

We can join max 32 table, it’s not possible to combine more then 32 tables.

In Tableau the joins can perform in 2 ways.

  1. By making use of common columns.
  2. By making use of common data types.

If we create joins on the fields in Tableau all the table names are suffixing with $. While performing the joins on multiple tables, always go with the les amount of data tables, so that we can improve the performance.

In Tableau the joins are divided into 2 types.

1.Equi Join,

2.Non Equi Join

  1. Equi Join: in the join condition if we are using Equality”=”operator then such a kind of join called as Equi join.
  2. Non Equi Join: in the join condition apart from the Equality”=”if we use any other operator like <,>,<=,>= and=! Then such a kind of joins are called as Non Equi Join

Equi Join is divided into 3 types

  1. Inner Join,
  2. Outer Join,
  3. Self – Join.

    1.Inner Join: Inner join will loads the only matching records from the both tables. Inner join condition:

           Tableaa.id = Tableb.id

  1. Outer Join:

  Again the outer join divided into 3 types.

  1. Left Outer Join,
  2. Right Outer Join,
  3. Full Outer Join.

Left outer join: displays the complete data from the left + matching records from the left.

Condition: tablea.id(+).

Right Outer Join: displays the complete data from the right + matching records from the left.

Condition: tablea.id(+)=tableb.id

Full outer join: full outer join load the complete data from the left table and right table. Condition: Table A full outer join Table B ON tablea.id= tableb.id

3.Self-Join: if we are performing join to the same table itself such a kind of join called as self-join

Non Equi Join:

In the join condition if we are using the operators apart from the equality “=” then such a kind of joins are called as Non Equi join.

Data Blending in Tableau:

For ex: your client is same Healthcare Client. They are operating their services in Asia, Europe, NA and so on & the are maintaining Asia data in SQL, Europe Data in SQL Server and NA data in MY SQL.

Now, your client wants to analyze their business across the world in a single worksheet. So you can’t perform join here.

Now you have make use of Data Blending Concept.

Normally in the Tableau we can perform the analysis on the single data server. If we want to perform the analysis from the multiple data sources in a single sheet then we have to make use of a new concept called as data blending.

Data blending mix the data from the different data sources and allow the users to perform th analysis in a single sheet. Blending means mixing. If we are mixing the data sources then it is called as data blending.

Rules to perform the data blending

In order to perform data blending there are few rules.

  1. If we are performing the data blending on 2 data source these 2 data sources should have at least 1 common dimension.
  2. In that common dimension at least 1 value should match.

In Tableau we can perform the data blending in 2 ways.

  1. Automatic way
  2. Custom way

1. Automatic way: In the automatic way Tableau automatically defines the relationship between the 2 data sources based on the common dimensions and based on the matching values and the relationship is indicated with Orange color.

2. Custom or Manual way: In the manual or custom way the user need to define the relationship manually.

Data blending fuctionality

  • All the primary data sources and the secondary data sources are linked by specific relationship
  • while performing the data blending each work sheet has a primary connection and optionally it might contains several secondary connections.
  • All the primary connections are indicated in the Blue in the work sheet and all the secondary data sources indicated with the Orange color tick mark.
  • In the data blending 1 sheet contains 1 primary data source and 1 sheet can contain end number of secondary data sources.

Q. What are Dimensions and Facts?

Dimensions is nothing but the descriptive text columns and facts are nothing but measures (numerical values) dimention ex:productname city..facts:sales, profit


Q. Can we place an excel file in a shared location and use it to develop a report and refresh it in regular intervals?

Yes you can do it… but for the better performance use extract


Q. What is the difference between heat map and tree map?

A heat map is a great way to compare categories using color and size. In this, you can compare two different measures. Tree map is a very powerful visualization, particularly for illustrating hierarchical (tree – structured) data and part – to – whole relationships.


Q. What is the different between twb and twbx file extensions. Please explain.

Twb is a live connection, it points to the data source; the user receiving twb needs permission to said data source and no data is included. .twbx takes data offline, stroes the data as a package or zip like file, thereby eradicating the need for permissions from end user, it’s now a snapshot in time of the data as of the time it was Saved as . twbx


Q. What is dual axis?

To display two measure in one graph


Q. What is blended axis?

Multiple Measures are shown in single axis and also all the marks shown in single pane

Drag a dimension in a column

Drag the first measure in column

Drag 2nd measure in existing axis

Http://onlinehelp.tableau.com/current/pro/online/mac/en-

Us/multiplemeasures_blendedaxes.html


Q. What makes Tableau software stand out?

In my view, Tableau stands out for several reasons:

First, most of the BI tools out there are pricey. However, Tableau has a free offering (Tableau Public) as well as a very popular (also free) academic distribution. Tableau is well recognized by firms like Forrester research to be one of the most easy to use, and agile products currently available. see here: Tableau Ranks #1 in The Forrester Wave: Advanced Data Visualization (ADV) Platforms That makes it easy to pick up and try new things with, which data visualization people love about it.

On the other hand, unlike some of the other BI tools, Tableau is not a complete technology stack, it is most useful for visualization and analytics. – you will need other products in addition to tableau for heavier enterprise data ETL, maintenance, and storage, etc. http://www.tableau.com/about/blog/2012/7/tableau-ranks-1-forrester-wave-advanced-data-visualization-adv-platforms-18522


Q. How do we do testing in Tableau?

You can’t test in Tableau as far as I know. It is a data visualization software.


Q. Can you get values from two different sources as a single input into parameter?

No you cannot. Each data source corresponds to a Tableau workbook. If you include both data variables in the same data source you can input them in the same workbook.


 Q. How many ways we use parameters in Tableau?

We can use parameters with filters, calculated fields ,actions, measure-swap, changing views and auto updates


Q. What is the use of new Custom SQL Query in tableau?

Custom SQL Query written after connecting to data for pulling the data in a structured view, One simple example is you have 50 columns in a table, but we need just 10 columns only. So instead of taking 50 columns you can write a sql query. Performance will increase.


Q. What are the differences between Tableau Software and Traditional BI tools?

Tableau provides easy to use, best in class, Visual Analytic capabilities, but it does not help with the plumbing (data foundation). You could, for example, marry SQL Server with Tableau to get the complete package. Tableau licenses are relatively expensive if you are looking to scale.

Traditional BI can handle it all but with significant upfront costs. Higher consulting, hardware and software costs. Among the mega-vendors, only Microsoft can provide a reasonable value proposition. Open source vendors like Pentaho and JasperSoft do not have an abundant enough talent pool, yet.


Q. What are the similarities and differences between Tableau software and Palantir?

Palantir and Tableau are very different. Palantir has its roots in large data computer science problems involving security, payments, fraud detection and the likes. Customers/Investors include Paypal, CIA and others.

Tableau is a visualization player – with roots in Stanford U research. It’s Visual Query Language (VizQL) allows users to build visualizations on top of standard data warehouses or spreadsheets.


Q. How to create cascading filters without context filter ?

I have filterl and filter2..Based on filterl I need to filter2 data

Ex: Filterl as Country and Filter 2: States

I have chosen country as INDIA and filter2 should display only INDIA states

Choose options of Filter2 states :

select option of “Only relevant values “


Q. Is Tableau Software good for a strategic acquisition?

Yes for sure! It gives you data insight to the extend that others don’t.

Helps u plan and point the anomalies and improvise your process for betterment.


Q. How to display top 5 and last 5 sales in same view?

Using filters or calculated fields we can able to display the top 5 and last 5 sales in same view?


Q. Design a view to show region wise profit and sales.I did not want line and bar chat should be used for profit and sales. How you will design and please explain?

Generate the Map using cities –>then Drag the Profit and sales to the Details–>Add the state as Quick filter


Q. Design a view in a map such that if user selects any state the cities under that state has to show profit and sales.

If you want to show the Sales and profit in each and every city under the states in the same work sheet. According to your question you should have State, City, Sales and Profit filed in your dataset.

  • Double click on the State filed.
  • Drag the City and drop into Marks card (under the State fied)
  • Drag the sales and drop into size.
  • Drag the profit and drop into color.
  • Click on Size legend and increase the size.(75%)
  • Right click on the State field and select show quick filter.
  • Select any state and check whether you got the required view or not. In this view size indicates the amount of sales and color indicates the Profit values

Q. Suppose my license expires today, can users able to view the dashboards or workbook which i published in server earlier.

If your server license expires today, your user name on the server will have the role ‘unlicensed’ which means you cannot access, but others can. The Site Admin can ‘Change Ownership’ to another person, so extracts if enabled do not fail.


Q. Think that I am using Tableau desktop and have a live connection to Cloud era hadoop data. I need to press F5 to refresh the visualization. Is there anyway to automatically refresh the visualization every x minutes instead of pressing F5 every-time?

Here is the example of refreshing dashboard in every 3 seconds, Replace api src and server url with yours. The interval below is for 3 seconds.

<DOCTYPE html>

<html lang=”en”>

<head>

<title>Tableau JavaScript API</title>

<script type=”text/javasdcript” src =http://servername/javascripts/api/tableau_v8.js>

</script>

</head>

<div id =”tableauViz”></div>

<script type=’text/javascript’>

Var placholderDiv = document.get Element By Id (“tableau Viz”);

Var options ={

Hidetabs : true,

Width:”100%”

Height:”1000px”

};

Var viz =new tableauSoftware. Viz (placehoderDiv,url,options);

setIntervfal(functions () {viz.refreshDataAsync();3000);

</script>

</body>

</html>


Q. How to add custom Color to Tableau?

Create Custom Color code in “Preferences.tps”

Navigation ::: Documents » My Table Repository »Preferences.tps

Add custom color code

Note: In tableau 9.0 version we have color picker option..


Q. How can we combine database and flat file data in tableau desktop?

Connect 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


Q. What is disaggregation and aggregation of data?

Suppose I have data like

Eid Ename Salary Dept

1.abc 2000 java

2.bbc 3000 .net

3.Krishna 2500 java

  1. Madhu 300

5.Vamshi 3000 mainframes

1.abc 1000 testing

2.bbc 3000 tableau

3.krishna 5000.net

4.Madhu 7000 testing

  1. vanshi 9000 tableau

1 abc 11000 Mainframes

2 bbc 13000testing

3 krishna 15000 java

4 Madhu 17000 .nte

5 vamshi 19000.net

Aggregation: to display aggregate data

Sum/avg salary by each individual employee

  1. drag ename on columna and salary on rows we will get sum (salary) of each and individual employee
  2. now change measure type as Avg

Choose salary option – choose measure types as “Avg”

Disaggregation: To display each and every transaction

When you look at the aggregated data in the views above, each bar represents all transactions for a specific employee summed up or averaged into a single value. Now say that you want to see the individual salary transactions for each employee. You can create a view like that by selecting Analysis>Aggregate Measures.


Q. What Does TABLEAU do?

Our goal is to help people see and understand data. Our software products put the power of data into the hands of everyday people, allowing a broad population of business users to engage with their data, ask questions, solve problems and create value


Q. What is Tableau Public? 

Tableau Public is a free service that lets anyone publish interactive data to the web. Once on the web, anyone can interact with the data, download it, or create their own visualizations of it. No programming skills are required. Be sure to look at the gallery to see some of the things people have been doing with it.


Q. What is data modelling?

Data modelling is the analysis of data objects that are used in a business or other context and the identification of the relationships among these data objects. Data modelling is a first step in doing object-oriented programming


Q. What is your daily work process in tableau?

I think we all work on different projects using Tableau, so the work begins from understanding the requirement getting the required data, story boarding then creating visualizations in tableau and then presenting it to the client for review.


Q. What is parameter in Tableau ? And how it works.?

 Parameters are dynamic values that can replace constant values in calculations and can serve as filters


Q. How does Tableau perform with huge datasets?

 Tableau Performance is based on Data source performance. If data source takes more time to execute a query then Tableau must wait up to that time.


Q. How will you publish and schedule workbook in tableau server?

First create a schedule for particular time and then create extract for the data source and publish the workbook for the server. Before you publish, there is a option called Scheduling and Authentication, click on that and select the schedule from the drop down which is created and publish. Also publish data source and assign the schedule. This schedule will automatically run for the assigned time and the workbook is refreshed.


Q. How to rectify SQL Performance for developed Dashboards

 After creation of Dashboards if we get problem from sql side that means Custom Sql ….How to Rectify the sql performance from custom sql


Q. Define the names for parameters ,filters etc…

 Parameters are dynamic values that can replace constant values in calculations and can serve as filters.Filters are used to restrict the data based on the condition u have mentioned in the filters shelf.


Q. How to view sql which is generated by Tableau Desktop?

 The Tableau Desktop Log files are located in C:\Users\\My Documents\My Tableau Repository. If you have a live connection to the data source, check the log.txt and tabprotosrv.txt files. If you are using an extract, check the tdeserver.txt file. The tabprotosrv.txt file often shows detailed information about queries.


Q. What is page shelf?

 page shelf is power full part of tableau That you can use to controle the display of output as well as printed results of output.


Q. What are the major differences between tableau version 7.0 and tableau version 8.0?

  • New visualizations are introduced like treemap, bubble chart and box and whisker plot
  • We can copy worksheet directly from one workbook to another workbook
  • Introduced R script

Q. How to create filled maps?

 Step 1: Build a Map View Double-click a geographic fields such as State, Area Code, Zip Code, etc.

Step 2: Select the Fille Map Mark Type The Automatic mark type will show this type of view as circles over a map. On the Marks card, select Filled Map to color the geographic areas.

Step 3: Drag a Field to the Color Shelf Define how the locations are colored by dragging another field to the Color shelf.


Q. Is Parameter have it’s dropdown list?

 Yes it may have its own drop down list, the entries which you make in the Parameter while creating it can be viewed as Dropdown list.


Q. What is Tableau Software?

Tableau is business intelligence software that allows anyone to easily connect to data, then visualize and create interactive, sharable dashboards. It’s easy enough that any Excel user can learn it, but powerful enough to satisfy even the most complex analytical problems. Securely sharing your findings with others only takes seconds.


Q. What is Tableau Server?

Tableau Server is browser- and mobile-based insight anyone can use. Publish dashboards with Tableau Desktop and share them throughout your organization. It’s easy to set up and even easier to run.


Q. Explain the integration of Tableau with R?

R is a popular open-source environment for statistical analysis. Tableau Desktop can now connect to R through calculated fields and take advantage of R functions, libraries, and packages and even saved models. These calculations dynamically invoke the R engine and pass values to R via the Rserve package, and are returned back to Tableau.

  • Tableau Server can also be configured to connect to an instance of Rserve through the tabadmin utility, allowing anyone to view a dashboard containing R functionality.
  • Combining R with Tableau gives you the ability to bring deep statistical analysis into a drag-and-drop visual analytics environment.

Q. What is the Difference between quick filter and Normal filter in tableau?

Quick filter is used to view the filtering options and can be used to select the option. Normal filer is something you can limit the options from the list or use some conditions to limit the data by field or value.


Q. How do I automate reports using Tableau software?

You need to publish report to tableau server, while publishing you will find one option to schedule reports.You just need to select the time when you want to refresh data.


Q. How is Tableau so fast when working with databases?

Tableau compiles the elements of your visual canvas into a SQL or MDX query for the remote database to process. Since a database typically runs on more powerful hardware than the laptops / workstations used by analysts, you should generally expect the database to handle queries much faster than most in memory BI applications limited by enduser hardware. Tableau’s ability to push computation (queries) close to the data is increasingly important for large data sets, which may reside on a fast cluster and may be too large to bring in memory.Another factor in performance relates to data transfer, or in Tableau’s case resultset transfer. Since Tableau visualizations are designed for human consumption, they are tailored to the capabilities and limits of the human perception system. This generally means that the amount of data in a query result set is small relative to the size of the underlying data, and visualizations focus on aggregation and filtering to identify trends and outliers. The small result sets require little network bandwidth, so Tableau is able to fetch and render the result set very quickly. And, as Ross mentioned, Tableau will cache query results for fast reuse.The last factor involves Tableau’s ability to use in memory acceleration as needed (for example, when working with very slow databases, text files, etc.). Tableau’s Data Engine uses memory mapped I/O, so while it takes advantage of in memory acceleration it can easily work with large data sets which cannot fit in memory. The Data Engine will work only with the subsets of data on disk which are needed for a given query, and the data subsets are mapped into memory as needed.


Q. What is Tableau Desktop?

Tableau Desktop is a data visualization application that lets you analyze virtually any type of structured data and produce highly interactive, beautiful graphs, dashboards, and reports in just minutes. After a quick installation, you can connect to virtually any data source from spreadsheets to data warehouses and display information in multiple graphic perspectives. Designed to be easy to use, you’ll be working faster than ever before.


Q. How Does Tableau Work?

While Tableau lets you analyze databases and spreadsheets like never before, you don’t need to know anything about databases to use Tableau. In fact, Tableau is designed to allow business people with no technical training to analyze their data efficiently.Tableau is based on three simple concepts:

         – Connect: Connect Tableau to any database that you want to analyze.

          Note that Tableau does not import the data. Instead it queries to the database directly.

       – Analyze: Analyzing data means viewing it, filtering it, sorting it, performing calculations on it, reorganizing it, summarizing it, and so on.Using Tableau you can do all of these things by simply arranging fields of your data source on a Tableau worksheet. When you drop a field on a worksheet, Tableau queries the data using standard drivers and query languages (like SQL and MDX) and presents a visual analysis of the data.

           – Share: You can share results with others either by sharing workbooks with other Tableau users, by pasting results into applications such as Microsoft Office, printing to PDF or by using Tableau Server to publish or embed your views across your organization.


Q. What is the difference between tableau 7.0 and 8.0 versions.

  • New visualizations are introduced like tree map bubble chart and box and whisker plot
  • We can copy worksheet directly from one workbook to another Workbook
  • Introduced R script

Q. Explain the features of Tableau 8.3?

        – With Kerboros support, Tableau 8.3 advances enterprise-grade data analysis with these enhancements:

  • Provides seamless, single sign-on experience from Tableau client to back-end data sources
  • Protects sensitive data with delegated access and viewer credential management
  • Connects to live data sources through stable, automated back-end authentication
  • Leverages existing IT investments in enterprise-grade authentication and data security
  • Supports smart card authentication

Tableau interview Questions will be part of the Mindmajix Tableau Training Program.


 

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